Synthesis of ultrathin nitrogen-doped graphitic carbon nanocages as advanced electrode materials for supercapacitor.

PubMed

Tan, Yueming; Xu, Chaofa; Chen, Guangxu; Liu, Zhaohui; Ma, Ming; Xie, Qingji; Zheng, Nanfeng; Yao, Shouzhuo

2013-03-01

Synthesis of nitrogen-doped carbons with large surface area, high conductivity, and suitable pore size distribution is highly desirable for high-performance supercapacitor applications. Here, we report a novel protocol for template synthesis of ultrathin nitrogen-doped graphitic carbon nanocages (CNCs) derived from polyaniline (PANI) and their excellent capacitive properties. The synthesis of CNCs involves one-pot hydrothermal synthesis of Mn3O4@PANI core-shell nanoparticles, carbonization to produce carbon coated MnO nanoparticles, and then removal of the MnO cores by acidic treatment. The CNCs prepared at an optimum carbonization temperature of 800 °C (CNCs-800) have regular frameworks, moderate graphitization, high specific surface area, good mesoporosity, and appropriate N doping. The CNCs-800 show high specific capacitance (248 F g(-1) at 1.0 A g(-1)), excellent rate capability (88% and 76% capacitance retention at 10 and 100 A g(-1), respectively), and outstanding cycling stability (~95% capacitance retention after 5000 cycles) in 6 M KOH aqueous solution. The CNCs-800 can also exhibit great pseudocapacitance in 0.5 M H2SO4 aqueous solution besides the large electrochemical double-layer capacitance. The excellent capacitance performance coupled with the facile synthesis of ultrathin nitrogen-doped graphitic CNCs indicates their great application potential in supercapacitors.

In situ fabrication of nickel aluminum-layered double hydroxide nanosheets/hollow carbon nanofibers composite as a novel electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

He, Fang; Hu, Zhibiao; Liu, Kaiyu; Zhang, Shuirong; Liu, Hongtao; Sang, Shangbin

2014-12-01

This paper introduces a new design route to fabricate nickel aluminum-layered double hydroxide (NiAl-LDH) nanosheets/hollow carbon nanofibers (CNFs) composite through an in situ growth method. The NiAl-LDH thin layers which grow on hollow carbon nanofibers have an average thickness of 13.6 nm. The galvanostatic charge-discharge test of the NiAl-LDH/CNFs composite yields an impressive specific capacitance of 1613 F g-1 at 1 A g-1 in 6 M KOH solution, the composite shows a remarkable specific capacitance of 1110 F g-1 even at a high current density of 10 A g-1. Furthermore, the composite remains a specific capacitance of 1406 F g-1 after 1000 cycles at 2 A g-1, indicating the composite has excellent high-current capacitive behavior and good cycle stability in compared to pristine NiAl-LDH.

Nanocomposite of polyaniline nanorods grown on graphene nanoribbons for highly capacitive pseudocapacitors.

PubMed

Li, Lei; Raji, Abdul-Rahman O; Fei, Huilong; Yang, Yang; Samuel, Errol L G; Tour, James M

2013-07-24

A facile and cost-effective approach to the fabrication of a nanocomposite material of polyaniline (PANI) and graphene nanoribbons (GNRs) has been developed. The morphology of the composite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron microscopy, and X-ray diffraction analysis. The resulting composite has a high specific capacitance of 340 F/g and stable cycling performance with 90% capacitance retention over 4200 cycles. The high performance of the composite results from the synergistic combination of electrically conductive GNRs and highly capacitive PANI. The method developed here is practical for large-scale development of pseudocapacitor electrodes for energy storage.

In situ self-sacrificed template synthesis of vanadium nitride/nitrogen-doped graphene nanocomposites for electrochemical capacitors.

PubMed

Liu, Hong-Hui; Zhang, Hong-Ling; Xu, Hong-Bin; Lou, Tai-Ping; Sui, Zhi-Tong; Zhang, Yi

2018-03-15

Vanadium nitride and graphene have been widely used as pseudo-capacitive and electric double-layer capacitor electrode materials for electrochemical capacitors, respectively. However, the poor cycling stability of vanadium nitride and the low capacitance of graphene impeded their practical applications. Herein, we demonstrated an in situ self-sacrificed template method for the synthesis of vanadium nitride/nitrogen-doped graphene (VN/NGr) nanocomposites by the pyrolysis of a mixture of dicyandiamide, glucose, and NH 4 VO 3 . Vanadium nitride nanoparticles of the size in the range of 2 to 7 nm were uniformly embedded into the nitrogen-doped graphene skeleton. Furthermore, the VN/NGr nanocomposites with a high specific surface area and pore volume showed a high specific capacitance of 255 F g -1 at 10 mV s -1 , and an excellent cycling stability (94% capacitance retention after 2000 cycles). The excellent capacitive properties were ascribed to the excellent conductivity of nitrogen-doped graphene, high surface area, high pore volume, and the synergistic effect between vanadium nitride and nitrogen-doped graphene.

Tuning the porosity of mesoporous NiO through calcining isostructural Ni-MOFs toward supercapacitor applications

NASA Astrophysics Data System (ADS)

Hou, Xiang-Yang; Yan, Xiao-Li; Wang, Xiao; Zhai, Quan-Guo

2018-07-01

NiO has an unusually high theoretical specific capacitance and possess relatively high electrical conductivity compared to other metal oxides. However, the reported specific capacitance of the NiO-based electrodes is far below the theoretical value up to now. In this paper, three porous NiO materials with different specific surface area were synthesized simply by calcining iso-structural Ni-based MOFs templates. The formation mechanism of NiO was discussed by taking into account the thermal behavior and intrinsic structural features of the Ni-MOFs. Taking advantages of the Ni-MOFs precursors, all prepared NiO compounds are mesoporous and their porosity can be tuned by the structure of MOFs. Specially, due to the high porosity, three NiO exhibited an improved electrochemical performance and the specific discharge capacitances are of 102, 105, and 116 F g-1 at the current density of 1 A g-1, respectively. The specific capacitance of 1-NiO-450 is approximately 93.2% of its maximum value after 3000 cycles, which obviously superior to most of the previously reported NiO electrode materials and suggests their promising applications in supercapacitors.

Three-Dimensional Honeycomb-Like Porous Carbon with Both Interconnected Hierarchical Porosity and Nitrogen Self-Doping from Cotton Seed Husk for Supercapacitor Electrode.

PubMed

Chen, Hui; Wang, Gang; Chen, Long; Dai, Bin; Yu, Feng

2018-06-08

Hierarchical porous structures with surface nitrogen-doped porous carbon are current research topics of interest for high performance supercapacitor electrode materials. Herein, a three-dimensional (3D) honeycomb-like porous carbon with interconnected hierarchical porosity and nitrogen self-doping was synthesized by simple and cost-efficient one-step KOH activation from waste cottonseed husk (a-CSHs). The obtained a-CSHs possessed hierarchical micro-, meso-, and macro-pores, a high specific surface area of 1694.1 m²/g, 3D architecture, and abundant self N-doping. Owing to these distinct features, a-CSHs delivered high specific capacitances of 238 F/g and 200 F/g at current densities of 0.5 A/g and 20 A/g, respectively, in a 6 mol/L KOH electrolyte, demonstrating good capacitance retention of 84%. The assembled a-CSHs-based symmetric supercapacitor also displayed high specific capacitance of 52 F/g at 0.5 A/g, with an energy density of 10.4 Wh/Kg at 300 W/Kg, and 91% capacitance retention after 5000 cycles at 10 A/g.

Three-dimensional skeleton networks of graphene wrapped polyaniline nanofibers: an excellent structure for high-performance flexible solid-state supercapacitors

PubMed Central

Hu, Nantao; Zhang, Liling; Yang, Chao; Zhao, Jian; Yang, Zhi; Wei, Hao; Liao, Hanbin; Feng, Zhenxing; Fisher, Adrian; Zhang, Yafei; Xu, Zhichuan J.

2016-01-01

Thin, robust, lightweight, and flexible supercapacitors (SCs) have aroused growing attentions nowadays due to the rapid development of flexible electronics. Graphene-polyaniline (PANI) hybrids are attractive candidates for high performance SCs. In order to utilize them in real devices, it is necessary to improve the capacitance and the structure stability of PANI. Here we report a hierarchical three-dimensional structure, in which all of PANI nanofibers (NFs) are tightly wrapped inside reduced graphene oxide (rGO) nanosheet skeletons, for high-performance flexible SCs. The as-fabricated film electrodes with this unique structure showed a highest gravimetric specific capacitance of 921 F/g and volumetric capacitance of 391 F/cm3. The assembled solid-state SCs gave a high specific capacitance of 211 F/g (1 A/g), a high area capacitance of 0.9 F/cm2, and a competitive volumetric capacitance of 25.6 F/cm3. The SCs also exhibited outstanding rate capability (~75% retention at 20 A/g) as well as excellent cycling stability (100% retention at 10 A/g for 2000 cycles). Additionally, no structural failure and loss of performance were observed under the bending state. This structure design paves a new avenue for engineering rGO/PANI or other similar hybrids for high performance flexible energy storage devices. PMID:26795067

Three-dimensional skeleton networks of graphene wrapped polyaniline nanofibers: An excellent structure for high-performance flexible solid-state supercapacitors

DOE PAGES

Hu, Nantao; Zhang, Liling; Yang, Chao; ...

2016-01-22

Thin, robust, lightweight, and flexible supercapacitors (SCs) have aroused growing attentions nowadays due to the rapid development of flexible electronics. Graphene-polyaniline (PANI) hybrids are attractive candidates for high performance SCs. In order to utilize them in real devices, it is necessary to improve the capacitance and the structure stability of PANI. Here we report a hierarchical three-dimensional structure, in which all of PANI nanofibers (NFs) are tightly wrapped inside reduced graphene oxide (rGO) nanosheet skeletons, for high-performance flexible SCs. The as-fabricated film electrodes with this unique structure showed a highest gravimetric specific capacitance of 921 F/g and volumetric capacitance ofmore » 391 F/cm 3. The assembled solid-state SCs gave a high specific capacitance of 211 F/g (1 A/g), a high area capacitance of 0.9 F/cm 2, and a competitive volumetric capacitance of 25.6 F/cm 3. The SCs also exhibited outstanding rate capability (~75% retention at 20 A/g) as well as excellent cycling stability (100% retention at 10 A/g for 2000 cycles). Additionally, no structural failure and loss of performance were observed under the bending state. Lastly, this structure design paves a new avenue for engineering rGO/PANI or other similar hybrids for high performance flexible energy storage devices.« less

Nitrogen-doped porous carbon derived from biomass waste for high-performance supercapacitor.

PubMed

Ma, Guofu; Yang, Qian; Sun, Kanjun; Peng, Hui; Ran, Feitian; Zhao, Xiaolong; Lei, Ziqiang

2015-12-01

High capacitance property and low cost are the pivotal requirements for practical application of supercapacitor. In this paper, a low cost and high capacitance property nitrogen-doped porous carbon with high specific capacitance is prepared. The as-prepared nitrogen-doped porous carbon employing potato waste residue (PWR) as the carbon source, zinc chloride (ZnCl2) as the activating agent and melamine as nitrogen doping agent. The morphology and structure of the carbon materials are studied by scanning electron microscopy (SEM), N2 adsorption/desorption, X-ray diffraction (XRD) and Raman spectra. The surface area of the nitrogen-doped carbon which prepared under 700°C is found to be 1052m(2)/g, and the specific capacitance as high as 255Fg(-1) in 2M KOH electrolyte is obtained utilize the carbon as electrode materials. The electrode materials also show excellent cyclability with 93.7% coulombic efficiency at 5Ag(-1) current density of for 5000cycles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Microwave-Assisted Synthesis of Highly-Crumpled, Few-Layered Graphene and Nitrogen-Doped Graphene for Use as High-Performance Electrodes in Capacitive Deionization

NASA Astrophysics Data System (ADS)

Amiri, Ahmad; Ahmadi, Goodarz; Shanbedi, Mehdi; Savari, Maryam; Kazi, S. N.; Chew, B. T.

2015-12-01

Capacitive deionization (CDI) is a promising procedure for removing various charged ionic species from brackish water. The performance of graphene-based material in capacitive deionization is lower than the expectation of the industry, so highly-crumpled, few-layered graphene (HCG) and highly-crumpled nitrogen-doped graphene (HCNDG) with high surface area have been introduced as promising candidates for CDI electrodes. Thus, HCG and HCNDG were prepared by exfoliation of graphite in the presence of liquid-phase, microwave-assisted methods. An industrially-scalable, cost-effective, and simple approach was employed to synthesize HCG and HCNDG, resulting in few-layered graphene and nitrogen-doped graphene with large specific surface area. Then, HCG and HCNDG were utilized for manufacturing a new class of carbon nanostructure-based electrodes for use in large-scale CDI equipment. The electrosorption results indicated that both the HCG and HCNDG have fairly large specific surface areas, indicating their huge potential for capacitive deionization applications.

In situ fabrication of nickel based oxide on nitrogen-doped graphene for high electrochemical performance supercapacitors

NASA Astrophysics Data System (ADS)

Pan, Denghui; Zhang, Mingmei; Wang, Ying; Yan, Zaoxue; Jing, Junjie; Xie, Jimin

2017-10-01

In this article, we synthesize Ni(OH)2 homogeneous grown on nitrogen-doped graphene (Ni(OH)2/NG), subsequently, small and uniform nickel oxide nanoparticle (NiO/NG) is also successfully obtained through tube furnace calcination method. The high specific capacitance of the NiO/NG electrode can reach to 1314.1 F/g at a charge and discharge current density of 2 A/g, meanwhile the specific capacitance of Ni(OH)2/NG electrode is also 1350 F/g. The capacitance of NiO/NG can remain 93.7% of the maximum value after 1000 cycles, while the Ni(OH)2/NG electrode losses 16.9% of the initial capacitance after 1000 cycles. It can be attributed to nickel hydroxide instability during charge-discharge cycles.

Effect of reducing system on capacitive behavior of reduced graphene oxide film: Application for supercapacitor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akbi, Hamdane; Yu, Lei; Wang, Bin

2015-01-15

To determine the best chemical reduction of graphene oxide film with hydriodic acid that gives maximum energy and power density, we studied the effect of two reducing systems, hydriodic acid/water and hydriodic acid/acetic acid, on the morphology and electrochemical features of reduced graphene oxide film. Using acetic acid as solvent results in high electrical conductivity (5195 S m{sup −1}), excellent specific capacitance (384 F g{sup −1}) and good cyclic stability (about 98% of its initial response after 4000 cycles). Using water as a solvent, results in an ideal capacitive behavior and excellent cyclic stability (about 6% increase of its initialmore » response after 2100 cycles). - Graphical abstract: The choice of reducing system determines the morphology and structure of the chemically reduced graphene film and, as a result, affects largely the capacitive behavior. - Highlights: • The structure of the graphene film has a pronounced effect on capacitive behavior. • The use of water/HI as reducing system results in an ideal capacitive behavior. • The use of acetic acid/HI as reducing system results in a high specific capacitance.« less

Synergistically Active NiCo2 S4 Nanoparticles Coupled with Holey Defect Graphene Hydrogel for High-Performance Solid-State Supercapacitors.

PubMed

Tiruneh, Sintayehu Nibret; Kang, Bong Kyun; Kwag, Sung Hoon; Lee, YoungHun; Kim, MinSeob; Yoon, Dae Ho

2018-03-02

Nickel cobalt sulfide nanoparticles embedded in holey defect graphene hydrogel (HGH) that exhibit highly porous structures and uniform nickel cobalt sulfide nanoparticle sizes are successfully prepared by a facile solvothermal-hydrothermal method. As an electrode material for supercapacitors, the as-prepared NiCo 2 S 4 @HGH shows ultra-high specific capacitances of 1000 F g -1 and 800 F g -1 at 0.5 and 6 A g -1 , respectively, owing to the outstanding electrical conductivity of HGH and high specific capacitance of NiCo 2 S 4 . After 2100 charge/discharge cycles at a current density of 6 A g -1 , 96.6 % of the specific capacitance was retained, signifying the superb durability of NiCo 2 S 4 @HGH. Moreover, remarkable specific capacitance (312.6 F g -1 ) and capacity retention (87 % after 5000 cycles) at 6 A g -1 were displayed by the symmetric solid-state supercapacitor fabricated by using NiCo 2 S 4 @HGH electrodes. These auspicious supercapacitor performances demonstrate that the as-developed solvothermal-hydrothermal approach can be widely used to prepare graphene-coupled binary metal sulfides for high-performance supercapacitor applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design, fabrication, and evaluation of on-chip micro-supercapacitors

NASA Astrophysics Data System (ADS)

Beidaghi, Majid

Due to the increasing demand for high power and reliable miniaturized energy storage devices, the development of micro-supercapacitors or electrochemical micro-capacitors have attracted much attention in recent years. This dissertation investigates several strategies to develop on-chip micro-supercapacitors with high power and energy density. Micro-supercapacitors based on interdigitated carbon micro-electrode arrays are fabricated through carbon microelectromechanical systems (C-MEMS) technique which is based on carbonization of patterned photoresist. To improve the capacitive behavior, electrochemical activation is performed on carbon micro-electrode arrays. The developed micro-supercapacitors show specific capacitances as high as 75 mFcm-2 at a scan rate of 5 mVs -1 after electrochemical activation for 30 minutes. The capacitance loss is less than 13% after 1000 cyclic voltammetry (CV) cycles. These results indicate that electrochemically activated C-MEMS micro-electrode arrays are promising candidates for on-chip electrochemical micro-capacitor applications. The energy density of micro-supercapacitors was further improved by conformal coating of polypyrrole (PPy) on C-MEMS structures. In these types of micro-devices the three dimensional (3D) carbon microstructures serve as current collectors for high energy density PPy electrodes. The electrochemical characterizations of these micro-supercapacitors show that they can deliver a specific capacitance of about 162.07 mFcm-2 and a specific power of 1.62mWcm -2 at a 20 mVs-1 scan rate. Addressing the need for high power micro-supercapacitors, the application of graphene as electrode materials for micro-supercapacitor was also investigated. The present study suggests a novel method to fabricate graphene-based micro-supercapacitors with thin film or in-plane interdigital electrodes. The fabricated micro-supercapacitors show exceptional frequency response and power handling performance and could effectively charge and discharge at rates as high as 50 Vs-1. CV measurements show that the specific capacitance of the micro-supercapacitor based on reduced graphene oxide and carbon nanotube composites is 6.1 mFcm -2 at scan rate of 0.01Vs-1. At a very high scan rate of 50 Vs-1, a specific capacitance of 2.8 mFcm-2 (stack capacitance of 3.1 Fcm-3) is recorded. This unprecedented performance can potentially broaden the future applications of micro-supercapacitors.

Three-dimensional cross-linked carbon network wrapped with ordered polyaniline nanowires for high-performance pseudo-supercapacitors

NASA Astrophysics Data System (ADS)

Hu, Huan; Liu, Shuwu; Hanif, Muddasir; Chen, Shuiliang; Hou, Haoqing

2014-12-01

The polyaniline (PANI)-based pseudo-supercapacitor has been extensively studied due to its good conductivity, ease of synthesis, low-cost monomer, tunable properties and remarkable specific capacitance. In this work, a three-dimensional cross-linked carbon network (3D-CCN) was used as a contact-resistance-free substrate for PANI-based pseudo-supercapacitors. The ordered PANI nanowires (PaNWs) were grown on the 3D-CCN to form PaNWs/3D-CCN composites by in-situ polymerization. The PaNWs/3D-CCN composites exhibited a specific capacitance (Cs) of 1191.8 F g-1 at a current density of 0.5 A g-1 and a superior rate capability with 66.4% capacitance retention at 100.0 A g-1. The high specific capacitance is attributed to the thin PaNW coating and the spaced PANI nanowire array, which ensure a higher utilization of PANI due to the ease of diffusion of protons through/on the PANI nanowires. In addition, the unique 3D-CCN was used as a high-conductivity platform (or skeleton) with no contact resistance for fast electron transfer and facile charge transport within the composites. Therefore, the binder-free composites can process rapid gains or losses of electrons and ions, even at a high current density. As a result, the specific capacitance and rate capability of our composites are remarkably higher than those of other PANI composites.

MOF-Derived Hollow Cage Nix Co3-x O4 and Their Synergy with Graphene for Outstanding Supercapacitors.

PubMed

Jayakumar, Anjali; Antony, Rajini P; Wang, Ronghua; Lee, Jong-Min

2017-03-01

Highly optimized nickel cobalt mixed oxide has been derived from zeolite imidazole frameworks. While the pure cobalt oxide gives only 178.7 F g -1 as the specific capacitance at a current density of 1 A g -1 , the optimized Ni:Co 1:1 has given an extremely high and unprecedented specific capacitance of 1931 F g -1 at a current density of 1 A g -1 , with a capacitance retention of 69.5% after 5000 cycles in a three electrode test. This optimized Ni:Co 1:1 mixed oxide is further used to make a composite of nickel cobalt mixed oxide/graphene 3D hydrogel for enhancing the electrochemical performance by virtue of a continuous and porous graphene conductive network. The electrode made from GNi:Co 1:1 successfully achieves an even higher specific capacitance of 2870.8 F g -1 at 1 A g -1 and also shows a significant improvement in the cyclic stability with 81% capacitance retention after 5000 cycles. An asymmetric supercapacitor is also assembled using a pure graphene 3D hydrogel as the negative electrode and the GNi:Co 1:1 as the positive electrode. With a potential window of 1.5 V and binder free electrodes, the capacitor gives a high specific energy density of 50.2 Wh kg -1 at a high power density of 750 W kg -1 . © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Few-layered Ni(OH)2 nanosheets for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Sun, Wenping; Rui, Xianhong; Ulaganathan, Mani; Madhavi, Srinivasan; Yan, Qingyu

2015-11-01

Few-layered Ni(OH)2 nanosheets (4-5 nm in thickness) are synthesized towards high-performance supercapacitors. The ultrathin Ni(OH)2 nanosheets show high specific capacitance and good rate capability in both three-electrode and asymmetric devices. In the three-electrode device, the Ni(OH)2 nanosheets deliver a high capacitance of 2064 F g-1 at 2 A g-1, and the capacitance still has a retention of 1837 F g-1 at a high current density of 20 A g-1. Such excellent performance is by far one of the best for Ni(OH)2 electrodes. In the two-electrode asymmetric device, the specific capacitance is 248 F g-1 at 1 A g-1, and reaches 113 F g-1 at 20 A g-1. The capacitance of the asymmetric device maintains to be 166 F g-1 during the 4000th cycle at 2 A g-1, suggesting good cycling stability of the device. Besides, the asymmetric device exhibits gravimetric energy density of 22 Wh kg-1 at a power density of 0.8 kW kg-1. The present results demonstrate that the ultrathin Ni(OH)2 nanosheets are highly attractive electrode materials for achieving fast charging/discharging and high-capacity supercapacitors.

Highly-wrinkled reduced graphene oxide-conductive polymer fibers for flexible fiber-shaped and interdigital-designed supercapacitors

NASA Astrophysics Data System (ADS)

Li, Bo; Cheng, Jianli; Wang, Zhuanpei; Li, Yinchuan; Ni, Wei; Wang, Bin

2018-02-01

Flexible supercapacitors have attracted great interest due to outstanding flexibility and light weight. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) fibers have the great potential in using as electrodes for flexible supercapacitors due to the good flexibility. However, the reported conductivity and specific capacitance of these PEDOT: PSS fibers are not very high, which limit their electrochemical performances. In this work, composite fibers of reduced graphene oxide(rGO)-PEDOT: PSS with a highly-wrinkled structure on the surface and pores inside are prepared by wet spinning. The fibers with different ratios of graphene to PEDOT:PSS show a distinctly enhanced conductivity up to ca. 590 S·cm-1 and high strength up to ca. 18.4 MPa. Meanwhile, the composite fibers show an improved electrochemical performances, including a high specific areal capacitance of 131 mF cm-2 and high specific areal energy density of 4.55 μWh·cm-2. The flexible supercapacitors including fiber-shaped supercapacitors and interdigital designed supercapacitors not only could work in different bending states without obvious capacitance decay, but also have small leakage current. The interdigital design can further improve the performances of composite fibers with high capacitance and high utilization compared with traditional parallel connected structure.

Hierarchically porous nitrogen-doped carbon derived from the activation of agriculture waste by potassium hydroxide and urea for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Zou, Kaixiang; Deng, Yuanfu; Chen, Juping; Qian, Yunqian; Yang, Yuewang; Li, Yingwei; Chen, Guohua

2018-02-01

Nitrogen-doped carbon with an ultra-high specific surface area and a hierarchically interconnected porous structure is synthesized in large scale from a green route, that is, the activation of bagasse via a one-step method using KOH and urea. KOH and urea play a synergistic effect for the enhancement of the specific surface area and the modification of pore size of the as-prepared material. Benefiting from the multiple synergistic roles originated from an ultra-high specific area (2905.4 m2 g-1), a high porous volume (2.05 mL g-1 with 75.6 vol% micropores, which is an ideal proportion of micropores for obtaining high specific capacitance), a suitable nitrogen content (2.63 wt%), and partial graphitization, the hierarchically interconnected porous N-doped carbon exhibits an excellent electrochemical performance with a high specific capacitance (350.8, 301.9, and 259.5 F g-1 at 1.0 A g-1 in acidic, alkaline, and neutral electrolytes, respectively), superior rate capability and excellent cycling stability (almost no capacitance loss up to 5000 cycles). Furthermore, the symmetric device assembled by this material achieves high energy densities of 39.1 and 23.5 Wh kg-1 at power densities of 1.0 and 20 kW kg-1, respectively, and exhibits an excellent long-term cycling stability (with capacitance retention above 95.0% after 10 000 cycles).

3D architecture of a graphene/CoMoO(4) composite for asymmetric supercapacitors usable at various temperatures.

PubMed

Jiang, Yaru; Zheng, Xin; Yan, Xiaoqin; Li, Yong; Zhao, Xuan; Zhang, Yue

2017-05-01

Designing and optimizing the electrode materials and studying the electrochemical performance or cycle life of the supercapacitor under different working conditions are crucial to its practical application. Herein, we proposed a rational design of 3D-graphene/CoMoO 4 nanoplates by a facile two-step hydrothermal method. Owing to the high electron transfer rate of graphene and the high activity of the CoMoO 4 nanoplates, the three-dimensional electrode architectures achieved remarkable electrochemical performances with high areal specific capacitance (1255.24F/g at 1A/g) and superior cycling stability (91.3% of the original specific capacitance after 3000 cycles at 1A/g). The all-solid-state asymmetric supercapacitor composed of 3D-graphene/CoMoO 4 and activated carbon (AC) exhibited a specific capacitance of 109F/g at 0.2A/g and an excellent cycling stability with only 12.1% of the initial specific capacitance off after 3000 cycles at 2A/g. The effects of temperature and charge-discharge current densities on the charge storage capacity of the supercapacitor were also investigated in detail for practical applications. Copyright © 2017 Elsevier Inc. All rights reserved.

Porous hollow Co₃O₄ with rhombic dodecahedral structures for high-performance supercapacitors.

PubMed

Zhang, Yi-Zhou; Wang, Yang; Xie, Ye-Lei; Cheng, Tao; Lai, Wen-Yong; Pang, Huan; Huang, Wei

2014-11-06

Porous hollow Co₃O₄ with rhombic dodecahedral structures were prepared by the calcination of ZIF-67 ([Co(mim)2; mim = 2-methylimidazolate]) rhombic dodecahedral microcrystals. A supercapacitor was successfully constructed by adopting the resulting porous hollow Co₃O₄ rhombic dodecahedral structure as the electrode material, which showed a large specific capacitance of 1100 F g(-1) and retained more than 95.1% of the specific capacitance after 6000 continuous charge-discharge cycles. The excellent capacitive properties and stability mark the porous hollow Co₃O₄ with the rhombic dodecahedral structure as one of the most promising electrode materials for high-performance supercapacitors.

High-performance Supercapacitors Based on Electrochemical-induced Vertical-aligned Carbon Nanotubes and Polyaniline Nanocomposite Electrodes

NASA Astrophysics Data System (ADS)

Wu, Guan; Tan, Pengfeng; Wang, Dongxing; Li, Zhe; Peng, Lu; Hu, Ying; Wang, Caifeng; Zhu, Wei; Chen, Su; Chen, Wei

2017-03-01

Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density. Here we report a high-performance supercapacitor based on polyaniline/vertical-aligned carbon nanotubes (PANI/VA-CNTs) nanocomposite electrodes where the vertical-aligned-structure is formed by the electrochemical-induction (0.75 V). The supercapacitor displays large specific capacitance of 403.3 F g-1, which is 6 times higher than disordered CNTs in HClO4 electrolyte. Additionally, the supercapacitor can also present high specific capacitance (314.6 F g-1), excellent cycling stability (90.2% retention after 3000 cycles at 4 A g-1) and high energy density (98.1 Wh kg-1) in EMIBF4 organic electrolyte. The key to high-performance lies in the vertical-aligned-structure providing direct path channel for ion faster diffusion and high electrochemical capacitance of polyaniline for ion more accommodation.

High-performance Supercapacitors Based on Electrochemical-induced Vertical-aligned Carbon Nanotubes and Polyaniline Nanocomposite Electrodes.

PubMed

Wu, Guan; Tan, Pengfeng; Wang, Dongxing; Li, Zhe; Peng, Lu; Hu, Ying; Wang, Caifeng; Zhu, Wei; Chen, Su; Chen, Wei

2017-03-08

Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density. Here we report a high-performance supercapacitor based on polyaniline/vertical-aligned carbon nanotubes (PANI/VA-CNTs) nanocomposite electrodes where the vertical-aligned-structure is formed by the electrochemical-induction (0.75 V). The supercapacitor displays large specific capacitance of 403.3 F g -1 , which is 6 times higher than disordered CNTs in HClO 4 electrolyte. Additionally, the supercapacitor can also present high specific capacitance (314.6 F g -1 ), excellent cycling stability (90.2% retention after 3000 cycles at 4 A g -1 ) and high energy density (98.1 Wh kg -1 ) in EMIBF 4 organic electrolyte. The key to high-performance lies in the vertical-aligned-structure providing direct path channel for ion faster diffusion and high electrochemical capacitance of polyaniline for ion more accommodation.

High-performance Supercapacitors Based on Electrochemical-induced Vertical-aligned Carbon Nanotubes and Polyaniline Nanocomposite Electrodes

PubMed Central

Wu, Guan; Tan, Pengfeng; Wang, Dongxing; Li, Zhe; Peng, Lu; Hu, Ying; Wang, Caifeng; Zhu, Wei; Chen, Su; Chen, Wei

2017-01-01

Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density. Here we report a high-performance supercapacitor based on polyaniline/vertical-aligned carbon nanotubes (PANI/VA-CNTs) nanocomposite electrodes where the vertical-aligned-structure is formed by the electrochemical-induction (0.75 V). The supercapacitor displays large specific capacitance of 403.3 F g−1, which is 6 times higher than disordered CNTs in HClO4 electrolyte. Additionally, the supercapacitor can also present high specific capacitance (314.6 F g−1), excellent cycling stability (90.2% retention after 3000 cycles at 4 A g−1) and high energy density (98.1 Wh kg−1) in EMIBF4 organic electrolyte. The key to high-performance lies in the vertical-aligned-structure providing direct path channel for ion faster diffusion and high electrochemical capacitance of polyaniline for ion more accommodation. PMID:28272474

Humic acids-based hierarchical porous carbons as high-rate performance electrodes for symmetric supercapacitors.

PubMed

Qiao, Zhi-jun; Chen, Ming-ming; Wang, Cheng-yang; Yuan, Yun-cai

2014-07-01

Two kinds of hierarchical porous carbons (HPCs) with specific surface areas of 2000 m(2)g(-1) were synthesized using leonardite humic acids (LHA) or biotechnology humic acids (BHA) precursors via a KOH activation process. Humic acids have a high content of oxygen-containing groups which enabled them to dissolve in aqueous KOH and facilitated the homogeneous KOH activation. The LHA-based HPC is made up of abundant micro-, meso-, and macropores and in 6M KOH it has a specific capacitance of 178 F g(-1) at 100 Ag(-1) and its capacitance retention on going from 0.05 to 100 A g(-1) is 64%. In contrast, the BHA-based HPC exhibits a lower capacitance retention of 54% and a specific capacitance of 157 F g(-1) at 100 A g(-1) which is due to the excessive micropores in the BHA-HPC. Moreover, LHA-HPC is produced in a higher yield than BHA-HPC (51 vs. 17 wt%). Copyright © 2014 Elsevier Ltd. All rights reserved.

A highly sensitive and specific capacitive aptasensor for rapid and label-free trace analysis of Bisphenol A (BPA) in canned foods.

PubMed

Mirzajani, Hadi; Cheng, Cheng; Wu, Jayne; Chen, Jiangang; Eda, Shigotoshi; Najafi Aghdam, Esmaeil; Badri Ghavifekr, Habib

2017-03-15

A rapid, highly sensitive, specific and low-cost capacitive affinity biosensor is presented here for label-free and single step detection of Bisphenol A (BPA). The sensor design allows rapid prototyping at low-cost using printed circuit board material by benchtop equipment. High sensitivity detection is achieved through the use of a BPA-specific aptamer as probe molecule and large electrodes to enhance AC-electroelectrothermal effect for long-range transport of BPA molecules toward electrode surface. Capacitive sensing technique is used to determine the bounded BPA level by measuring the sample/electrode interfacial capacitance of the sensor. The developed biosensor can detect BPA level in 20s and exhibits a large linear range from 1 fM to 10 pM, with a limit of detection (LOD) of 152.93 aM. This biosensor was applied to test BPA in canned food samples and could successfully recover the levels of spiked BPA. This sensor technology is demonstrated to be highly promising and reliable for rapid, sensitive and on-site monitoring of BPA in food samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Noncovalently-functionalized reduced graphene oxide sheets by water-soluble methyl green for supercapacitor application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Xiaoying; Hu, Zhongai, E-mail: zhongai@nwnu.edu.cn; Hu, Haixiong

2015-10-15

Graphical abstract: Electroactive methyl green (MG) is selected to functionalize reduced graphene oxide (RGO) through non-covalent modification and the composite achieves high specific capacitance, good rate capability and excellent long life cycle. - Highlights: • MG–RGO composites were firstly prepared through non-covalent modification. • The mass ratio in composites is a key for achieving high specific capacitance. • MG–RGO 5:4 exhibits the highest specific capacitance of 341 F g{sup −1}. • MG–RGO 5:4 shows excellent rate capability and long life cycle. - Abstract: In the present work, water-soluble electroactive methyl green (MG) has been used to non-covalently functionalize reduced graphenemore » oxide (RGO) for enhancing supercapacitive performance. The microstructure, composition and morphology of MG–RGO composites are systematically characterized by UV–vis absorption, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical performances are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). The fast redox reactions from MG could generate additional pseudocapacitance, which endows RGO higher capacitances. As a result, the MG–RGO composite (with the 5:4 mass ratio of MG:RGO) achieve a maximum value of 341 F g{sup −1} at 1 A g{sup −1} within the potential range from −0.25 to 0.75 V and provide a 180% enhancement in specific capacitance in comparison with pure RGO. Furthermore, excellent rate capability (72% capacitance retention from 1 A g{sup −1} to 20 A g{sup −1}) and long life cycle (12% capacitance decay after 5000 cycles) are achieved for the MG–RGO composite electrode.« less

Highly Compressible Carbon Sponge Supercapacitor Electrode with Enhanced Performance by Growing Nickel-Cobalt Sulfide Nanosheets.

PubMed

Liang, Xu; Nie, Kaiwen; Ding, Xian; Dang, Liqin; Sun, Jie; Shi, Feng; Xu, Hua; Jiang, Ruibin; He, Xuexia; Liu, Zonghuai; Lei, Zhibin

2018-03-28

The development of compressible supercapacitor highly relies on the innovative design of electrode materials with both superior compression property and high capacitive performance. This work reports a highly compressible supercapacitor electrode which is prepared by growing electroactive NiCo 2 S 4 (NCS) nanosheets on the compressible carbon sponge (CS). The strong adhesion of the metallic conductive NCS nanosheets to the highly porous carbon scaffolds enable the CS-NCS composite electrode to exhibit an enhanced conductivity and ideal structural integrity during repeated compression-release cycles. Accordingly, the CS-NCS composite electrode delivers a specific capacitance of 1093 F g -1 at 0.5 A g -1 and remarkable rate performance with 91% capacitance retention in the range of 0.5-20 A g -1 . Capacitance performance under the strain of 60% shows that the incorporation of NCS nanosheets in CS scaffolds leads to over five times enhancement in gravimetric capacitance and 17 times enhancement in volumetric capacitance. These performances enable the CS-NCS composite to be one of the promising candidates for potential applications in compressible electrochemical energy storage devices.

Electrostatic Induced Stretch Growth of Homogeneous β-Ni(OH)2 on Graphene with Enhanced High-Rate Cycling for Supercapacitors

PubMed Central

Wu, Zhong; Huang, Xiao-Lei; Wang, Zhong-Li; Xu, Ji-Jing; Wang, Heng-Guo; Zhang, Xin-Bo

2014-01-01

Supercapacitors, as one of alternative energy devices, have been characterized by the rapid rate of charging and discharging, and high power density. But they are now challenged to achieve their potential energy density that is related to specific capacitance. Thus it is extremely important to make such materials with high specific capacitances. In this report, we have gained homogenous Ni(OH)2 on graphene by efficiently using of a facile and effective electrostatic induced stretch growth method. The electrostatic interaction triggers advantageous change in morphology and the ordered stacking of Ni(OH)2 nanosheets on graphene also enhances the crystallization of Ni(OH)2. When the as-prepared Ni(OH)2/graphene composite is applied to supercapacitors, they show superior electrochemical properties including high specific capacitance (1503 F g−1 at 2 mV s−1) and excellent cycling stability up to 6000 cycles even at a high scan rate of 50 mV s−1. PMID:24413283

Carbon-polyaniline nanocomposites as supercapacitor materials

NASA Astrophysics Data System (ADS)

Sathish Kumar, M.; Yamini Yasoda, K.; Batabyal, Sudip Kumar; Kothurkar, Nikhil K.

2018-04-01

Polyaniline-based nanocomposites containing carbon nanotubes (CNT), reduced graphene oxide (rGO) and mixture of CNTs and rGO were synthesized. UV-visible spectroscopy and FT-IR spectroscopy confirmed the presence of polyaniline (PANi) and carbon nanomaterials. Scanning electron microscopy revealed that the neat PANi had a granular morphology, which can lead to increased electrical resistance to high interfacial resistance between domains of PANi. Cyclic voltammetry of PANi, PANi/CNT, PANi/rGO and PANi/CNT/rGO showed that in general, specific capacitance reduces with increasing scan rate within the range (10–100 mV s‑1). Also the specific capacitance values at any given scan rate within the above range, for PANi, PANi/CNT, PANi/rGO and PANi/CNT/rGO were found to be in increasing order. The specific capacitance of the PANi/CNT/rGO nanocomposite as measured by galvanostatic charge-discharge measurements, was found to be 312.5 F g‑1. The introduction of the carbon nanomaterials (CNTs, rGO) in PANi in general leads to improved specific capacitance, while the addition of CNTs and rGO together leads to synergistic improvement in the specific capacitance, owing to a combination of factors.

Synthesis and characterization of RuO(2)/poly(3,4-ethylenedioxythiophene) composite nanotubes for supercapacitors.

PubMed

Liu, Ran; Duay, Jonathon; Lane, Timothy; Bok Lee, Sang

2010-05-07

We report the synthesis of composite RuO(2)/poly(3,4-ethylenedioxythiophene) (PEDOT) nanotubes with high specific capacitance and fast charging/discharging capability as well as their potential application as electrode materials for a high-energy and high-power supercapacitor. RuO(2)/PEDOT nanotubes were synthesized in a porous alumina membrane by a step-wise electrochemical deposition method, and their structures were characterized using electron microscopy. Cyclic voltammetry was used to qualitatively characterize the capacitive properties of the composite RuO(2)/PEDOT nanotubes. Their specific capacitance, energy density and power density were evaluated by galvanostatic charge/discharge cycles at various current densities. The pseudocapacitance behavior of these composite nanotubes originates from ion diffusion during the simultaneous and parallel redox processes of RuO(2) and PEDOT. We show that the energy density (specific capacitance) of PEDOT nanotubes can be remarkably enhanced by electrodepositing RuO(2) into their porous walls and onto their rough internal surfaces. The flexible PEDOT prevents the RuO(2) from breaking and detaching from the current collector while the rigid RuO(2) keeps the PEDOT nanotubes from collapsing and aggregating. The composite RuO(2)/PEDOT nanotube can reach a high power density of 20 kW kg(-1) while maintaining 80% energy density (28 Wh kg(-1)) of its maximum value. This high power capability is attributed to the fast charge/discharge of nanotubular structures: hollow nanotubes allow counter-ions to readily penetrate into the composite material and access their internal surfaces, while a thin wall provides a short diffusion distance to facilitate ion transport. The high energy density originates from the RuO(2), which can store high electrical/electrochemical energy intrinsically. The high specific capacitance (1217 F g(-1)) which is contributed by the RuO(2) in the composite RuO(2)/PEDOT nanotube is realized because of the high specific surface area of the nanotubular structures. Such PEDOT/RuO(2) composite nanotube materials are an ideal candidate for the development of high-energy and high-power supercapacitors.

Three Dimensional Nitrogen-Doped and Nitrogen, Sulfur-Codoped Graphene Hydrogels for Electrode Materials in Supercapacitors.

PubMed

Yuan, Zhao; Qiao, Fei; Wang, Guiqiang; Zhou, Jin; Cui, Hongyou; Zhuo, Shuping; Xing, Ling-Bao

2018-08-01

In present work, reduced graphene oxide hydrogels (RGOHs) with three-dimensional (3D) porous structure are prepared through chemical reduction method by using aminourea (NRGOHs) and aminothiourea (NSRGOHs) as reductants. The as-prepared RGOHs are considered not only as promising electrode materials for supercapacitors, but also the doping of nitrogen (aminourea, NRGOHs) or nitrogen/sulfur (aminothiourea, NSRGOHs) can improve electrochemical performance through faradaic pseudocapacitance. The optimized samples have been prepared by controlling the mass ratios of graphene oxide (GO) to aminourea or aminothiourea to be 1:1, 1:2 and 1:5, respectively. With adding different amounts of aminourea or aminothiourea, the obtained RGOHs exhibited different electrochemical performance in supercapacitors. With increasing the dosage of the reductants, the RGOHs revealed better specific capacitances. Moreover, NSRGOHs with nitrogen, sulfur-codoping exhibited better capacitance performance than that of NRGOHs with only nitrogen-doping. NSRGOHs showed excellent capacitive performance with a very high specific capacitance up to 232.2, 323.3 and 345.6 F g-1 at 0.2 A g-1, while NRGOHs showed capacitive performance with specific capacitance up to 220.6, 306.5 and 332.7 F g-1 at 0.2 A g-1. This provides a strategy to improve the capacitive properties of RGOHs significantly by controlling different doping the materials.

Isolating the effect of pore size distribution on electrochemical double-layer capacitance using activated fluid coke

NASA Astrophysics Data System (ADS)

Zuliani, Jocelyn E.; Tong, Shitang; Kirk, Donald W.; Jia, Charles Q.

2015-12-01

Electrochemical double-layer capacitors (EDLCs) use physical ion adsorption in the capacitive electrical double layer of high specific surface area (SSA) materials to store electrical energy. Previous work shows that the SSA-normalized capacitance increases when pore diameters are less than 1 nm. However, there still remains uncertainty about the charge storage mechanism since the enhanced SSA-normalized capacitance is not observed in all microporous materials. In previous studies, the total specific surface area and the chemical composition of the electrode materials were not controlled. The current work is the first reported study that systematically compares the performance of activated carbon prepared from the same raw material, with similar chemical composition and specific surface area, but different pore size distributions. Preparing samples with similar SSAs, but different pores sizes is not straightforward since increasing pore diameters results in decreasing the SSA. This study observes that the microporous activated carbon has a higher SSA-normalized capacitance, 14.1 μF cm-2, compared to the mesoporous material, 12.4 μF cm-2. However, this enhanced SSA-normalized capacitance is only observed above a threshold operating voltage. Therefore, it can be concluded that a minimum applied voltage is required to induce ion adsorption in these sub-nanometer micropores, which increases the capacitance.

Mesoporous coaxial titanium nitride-vanadium nitride fibers of core-shell structures for high-performance supercapacitors.

PubMed

Zhou, Xinhong; Shang, Chaoqun; Gu, Lin; Dong, Shanmu; Chen, Xiao; Han, Pengxian; Li, Lanfeng; Yao, Jianhua; Liu, Zhihong; Xu, Hongxia; Zhu, Yuwei; Cui, Guanglei

2011-08-01

In this study, titanium nitride-vanadium nitride fibers of core-shell structures were prepared by the coaxial electrospinning, and subsequently annealed in the ammonia for supercapacitor applications. These core-shell (TiN-VN) fibers incorporated mesoporous structure into high electronic conducting transition nitride hybrids, which combined higher specific capacitance of VN and better rate capability of TiN. These hybrids exhibited higher specific capacitance (2 mV s(-1), 247.5 F g(-1)) and better rate capability (50 mV s(-1), 160.8 F g(-1)), which promise a good candidate for high-performance supercapacitors. It was also revealed by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) characterization that the minor capacitance fade originated from the surface oxidation of VN and TiN.

Aligned carbon nanotube/zinc oxide nanowire hybrids as high performance electrodes for supercapacitor applications

NASA Astrophysics Data System (ADS)

Al-Asadi, Ahmed S.; Henley, Luke Alexander; Wasala, Milinda; Muchharla, Baleeswaraiah; Perea-Lopez, Nestor; Carozo, Victor; Lin, Zhong; Terrones, Mauricio; Mondal, Kanchan; Kordas, Krisztian; Talapatra, Saikat

2017-03-01

Carbon nanotube/metal oxide based hybrids are envisioned as high performance electrochemical energy storage electrodes since these systems can provide improved performances utilizing an electric double layer coupled with fast faradaic pseudocapacitive charge storage mechanisms. In this work, we show that high performance supercapacitor electrodes with a specific capacitance of ˜192 F/g along with a maximum energy density of ˜3.8 W h/kg and a power density of ˜ 28 kW/kg can be achieved by synthesizing zinc oxide nanowires (ZnO NWs) directly on top of aligned multi-walled carbon nanotubes (MWCNTs). In comparison to pristine MWCNTs, these constitute a 12-fold of increase in specific capacitance as well as corresponding power and energy density values. These electrodes also possess high cycling stability and were able to retain ˜99% of their specific capacitance value over 2000 charging discharging cycles. These findings indicate potential use of a MWCNT/ZnO NW hybrid material for future electrochemical energy storage applications.

Synthesis of a highly efficient 3D graphene-CNT-MnO2-PANI nanocomposite as a binder free electrode material for supercapacitors.

PubMed

Asif, Muhammad; Tan, Yi; Pan, Lujun; Rashad, Muhammad; Li, Jiayan; Fu, Xin; Cui, Ruixue

2016-09-29

Graphene based nanocomposites have been investigated intensively, as electrode materials for energy storage applications. In the current work, a graphene-CNT-MnO 2 -PANI (GCM@PANI) nanocomposite has been synthesized on 3D graphene grown on nickel foam, as a highly efficient binder free electrode material for supercapacitors. Interestingly, the specific capacitance of the synthesized electrode increases up to the first 1500 charge-discharge cycles, and is thus referred to as an electrode activation process. The activated GCM@PANI nanocomposite electrode exhibits an extraordinary galvanostatic specific capacitance of 3037 F g -1 at a current density of 8 A g -1 . The synthesized nanocomposite exhibits an excellent cyclic stability with a capacitance retention of 83% over 12 000 charge-discharge cycles, and a high rate capability by retaining a specific capacitance of 84.6% at a current density of 20 A g -1 . The structural and electrochemical analysis of the synthesized nanocomposite suggests that the astonishing electrochemical performance might be attributed to the growth of a novel PANI nanoparticle layer and the synergistic effect of CNT/MnO 2 nanostructures.

Template method to controllable synthesis 3D porous NiCo2O4 with enhanced capacitance and stability for supercapacitors.

PubMed

Bai, Yang; Wang, Ranran; Lu, Xiaoyu; Sun, Jing; Gao, Lian

2016-04-15

We present a facile template method to fabricate NiCo2O4 (NCO) composites with 3D porous structure as electrodes for supercapacitors. SiO2 sol is used as the template to prevent the aggregation of NCO and construct the porous structure with high specific surface area. Meanwhile, the binary metal oxides not only inherit the merits of single nickel oxides or cobalt oxides, but also show superior properties to promote the capacitance. The uniform structure of NCO12 (SiO2/NCO=1:2) is obtained through controlling the mass ratio of SiO2 and NCO. Owing to the dual advantages of porous structure and binary system, NCO12 composites exhibit highly enhanced electrochemical performance compared with those of directly prepared NCO, NCO21 (SiO2/NCO=1:0.5) and NCO14 (SiO2/NCO=1:4). The specific capacitance of NCO12 composite is about 1389 Fg(-1) at 1 Ag(-1). At 4 Ag(-1), the capacitance is still as high as 1090 Fg(-1) together with capacitance retention of 80% over 2500 cycles. The capacitance and stability are higher than those of most previously reported pure NCO composites, which make it a very promising electrode material for energy storage. Copyright © 2016 Elsevier Inc. All rights reserved.

Facile coating of manganese oxide on tin oxide nanowires with high-performance capacitive behavior.

PubMed

Yan, Jian; Khoo, Eugene; Sumboja, Afriyanti; Lee, Pooi See

2010-07-27

In this paper, a very simple solution-based method is employed to coat amorphous MnO2 onto crystalline SnO2 nanowires grown on stainless steel substrate, which utilizes the better electronic conductivity of SnO2 nanowires as the supporting backbone to deposit MnO2 for supercapacitor electrodes. Cyclic voltammetry (CV) and galvanostatic charge/discharge methods have been carried out to study the capacitive properties of the SnO2/MnO2 composites. A specific capacitance (based on MnO2) as high as 637 F g(-1) is obtained at a scan rate of 2 mV s(-1) (800 F g(-1) at a current density of 1 A g(-1)) in 1 M Na2SO4 aqueous solution. The energy density and power density measured at 50 A g(-1) are 35.4 W h kg(-1) and 25 kW kg(-1), respectively, demonstrating the good rate capability. In addition, the SnO2/MnO2 composite electrode shows excellent long-term cyclic stability (less than 1.2% decrease of the specific capacitance is observed after 2000 CV cycles). The temperature-dependent capacitive behavior is also discussed. Such high-performance capacitive behavior indicates that the SnO2/MnO2 composite is a very promising electrode material for fabricating supercapacitors.

Mechanochemical synthesis of carbon-based nanocomposites for supercapacitors

NASA Astrophysics Data System (ADS)

Mateyshina, Yuliya G.; Ulihin, Artem S.; Uvarov, Nikolai F.

2014-12-01

New nanoporous carbon-SiO2 composite materials were synthesized from organic raw materials (rice shells) and their electrochemical properties were investigated by cyclic voltammetry in liquid electrolytes (6 M KOH or 1 M H2SO4). A correlation between specific capacitance and specific surface area was observed. Due to high specific capacitance of 90 F/g the carbon materials under study may be regarded as promising electrode materials for electrochemical supercapacitors.

Enhanced capacitance and rate capability of graphene/polypyrrole composite as electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Zhang, Dacheng; Zhang, Xiong; Chen, Yao; Yu, Peng; Wang, Changhui; Ma, Yanwei

Graphene and polypyrrole composite (PPy/GNS) is synthesized via in situ polymerization of pyrrole monomer in the presence of graphene under acid conditions. The structure and morphology of the composite are characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectrometer (FTIR), X-rays photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). It is found that a uniform composite is formed with polypyrrole being homogeneously surrounded by graphene nanosheets (GNS). The composite is a promising candidate for supercapacitors to have higher specific capacitance, better rate capability and cycling stability than those of pure polypyrrole. The specific capacitance of PPy/GNS composite based on the three-electrode cell configuration is as high as 482 F g -1 at a current density of 0.5 A g -1. After 1000 cycles, the attenuation of the specific capacitance is less than 5%, indicating that composite has excellent cycling performance.

Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

NASA Astrophysics Data System (ADS)

Lee, Hae-Min; Jeong, Gyoung Hwa; Kim, Sang-Wook; Kim, Chang-Koo

2017-04-01

Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2-5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

Gram-scale production of B, N co-doped graphene-like carbon for high performance supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Chen, Zhuo; Hou, Liqiang; Cao, Yan; Tang, Yushu; Li, Yongfeng

2018-03-01

Boron and nitrogen co-doped graphene-like carbon (BNC) with a gram scale was synthesized via a two-step method including a ball-milling process and a calcination process and used as electrode materials for supercapacitors. High surface area and abundant active sites of graphene-like carbon were created by the ball-milling process. Interestingly, the nitrogen atoms are doped in carbon matrix without any other N sources except for air. The textual and chemical properties can be easily tuned by changing the calcination temperature, and at 900 oC the BNC with a high surface area (802.35 m2/g), a high boron content (2.19 at%), a hierarchical pore size distribution and a relatively high graphitic degree was obtained. It shows an excellent performance of high specific capacitance retention about 78.2% at high current density (199 F/g at 100 A/g) of the initial capacitance (254 F/g at 0.25 A/g) and good cycling stability (90% capacitance retention over 1000 cycles at 100 A/g) measured in a three-electrode system. Furthermore, in a two-electrode system, a specific capacitance of 225 F/g at 0.25 A/g and a good cycling stability (93% capacitance retention over 20,000 cycles at 25 A/g) were achieved by using BNC as electrodes. The strategy of synthesis is facile and effective to fabricate multi-doped graphene-like carbon for promising candidates as electrode materials in supercapacitors.

Superelastic supercapacitors with high performances during stretching.

PubMed

Zhang, Zhitao; Deng, Jue; Li, Xueyi; Yang, Zhibin; He, Sisi; Chen, Xuli; Guan, Guozhen; Ren, Jing; Peng, Huisheng

2015-01-14

A fiber-shaped supercapacitor that can be stretched over 400% is developed by using two aligned carbon nanotube/polyaniline composite sheets as electrodes. A high specific capacitance of approximately 79.4 F g(-1) is well maintained after stretching at a strain of 300% for 5000 cycles or 100.8 F g(-1) after bending for 5000 cycles at a current density of 1 A g(-1). In particular, the high specific capacitance is maintained by 95.8% at a stretching speed as high as 30 mm s(-1). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A porous ceramic membrane tailored high-temperature supercapacitor

NASA Astrophysics Data System (ADS)

Zhang, Xin; He, Benlin; Zhao, Yuanyuan; Tang, Qunwei

2018-03-01

The supercapacitor that can operate at high-temperature are promising for markedly increase in capacitance because of accelerated charge movement. However, the state-of-the-art polymer-based membranes will decompose at high temperature. Inspired by solid oxide fuel cells, we present here the experimental realization of high-temperature supercapacitors (HTSCs) tailored with porous ceramic separator fabricated by yttria-stabilized zirconia (YSZ) and nickel oxide (NiO). Using activated carbon electrode and supporting electrolyte from potassium hydroxide (KOH) aqueous solution, a category of symmetrical HTSCs are built in comparison with a conventional polymer membrane based device. The dependence of capacitance performance on temperature is carefully studied, yielding a maximized specific capacitance of 272 F g-1 at 90 °C for the optimized HTSC tailored by NiO/YSZ membrane. Moreover, the resultant HTSC has relatively high durability when suffer repeated measurement over 1000 cycles at 90 °C, while the polymer membrane based supercapacitor shows significant reduction in capacitance at 60 °C. The high capacitance along with durability demonstrates NiO/YSZ membrane tailored HTSCs are promising in future advanced energy storage devices.

Nano-aggregates of cobalt nickel oxysulfide as a high-performance electrode material for supercapacitors.

PubMed

Liu, Lifeng

2013-12-07

Nano-aggregates of cobalt nickel oxysulfide (CoNi)OxSy have been synthesized by hydrothermal processing and exhibited specific and areal capacitance as high as 592 F g(-1) and 1628 mF cm(-2), respectively, at a current density of 0.5 A g(-1)/1.375 mA cm(-2). They also show high capacitance retention upon extended cycling at high rates.

High-surface-area nitrogen-doped reduced graphene oxide for electric double-layer capacitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Youn, Hee-Chang; Bak, Seong-Min; Kim, Myeong-Seong

A two-step method consisting of solid-state microwave irradiation and heat treatment under NH₃ gas was used to prepare nitrogen-doped reduced graphene oxide (N-RGO) with a high specific surface area (1007m²g⁻¹), high electrical conductivity (1532S m⁻¹), and low oxygen content (1.5 wt%) for electric double-layer capacitor applications. The specific capacitance of N-RGO was 291 Fg⁻¹ at a current density of 1 A g⁻¹, and a capacitance of 261 F g⁻¹ was retained at 50 A g⁻¹, indicating a very good rate capability. N-RGO also showed excellent cycling stability, preserving 96% of the initial specific capacitance after 100,000 cycles. Near-edge X-ray absorptionmore » fine-structure spectroscopy evidenced the recover of π-conjugation in the carbon networks with the removal of oxygenated groups and revealed the chemical bonding of the nitrogen atoms in N-RGO. The good electrochemical performance of N-RGO is attributed to its high surface area, high electrical conductivity, and low oxygen content.« less

High-surface-area nitrogen-doped reduced graphene oxide for electric double-layer capacitors

DOE PAGES

Youn, Hee-Chang; Bak, Seong-Min; Kim, Myeong-Seong; ...

2015-06-08

A two-step method consisting of solid-state microwave irradiation and heat treatment under NH₃ gas was used to prepare nitrogen-doped reduced graphene oxide (N-RGO) with a high specific surface area (1007m²g⁻¹), high electrical conductivity (1532S m⁻¹), and low oxygen content (1.5 wt%) for electric double-layer capacitor applications. The specific capacitance of N-RGO was 291 Fg⁻¹ at a current density of 1 A g⁻¹, and a capacitance of 261 F g⁻¹ was retained at 50 A g⁻¹, indicating a very good rate capability. N-RGO also showed excellent cycling stability, preserving 96% of the initial specific capacitance after 100,000 cycles. Near-edge X-ray absorptionmore » fine-structure spectroscopy evidenced the recover of π-conjugation in the carbon networks with the removal of oxygenated groups and revealed the chemical bonding of the nitrogen atoms in N-RGO. The good electrochemical performance of N-RGO is attributed to its high surface area, high electrical conductivity, and low oxygen content.« less

3D flower-like hierarchical Ag@nickel-cobalt hydroxide microsphere with enhanced electrochemical properties

NASA Astrophysics Data System (ADS)

Lv, Zijian; Zhong, Qin; Bu, Yunfei; Wu, Junpeng

2016-10-01

The morphology and electrical conductivity are essential to electrochemical performance of electrode materials in renewable energy conversion and storage technologies such as fuel cells and supercapacitors. Here, we explored a facile method to grow Ag@nickel-cobalt layered double hydroxide (Ag@Ni/Co-LDHs) with 3D flower-like microsphere structure. The results show the morphology of Ni/Co-LDHs varies with the introduction of Ag species. The prepared Ag@Ni/Co-LDHs not only exhibits an open hierarchical structure with high specific capacitance but also shows good electrical conductivity to support fast electron transport. Benefiting from the unique structural features, these flower-like Ag@Ni/Co-LDHs microspheres have impressive specific capacitance as high as 1768 F g-1 at 1 A g-1. It can be concluded that engineering the structure of the electrode can increase the efficiency of the specific capacitance as a battery-type electrode for hybrid supercapacitors.

Hierarchical MoS2 nanowires/NiCo2O4 nanosheets supported on Ni foam for high-performance asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Wen, Shiyang; Liu, Yu; Zhu, Fangfang; Shao, Rong; Xu, Wei

2018-01-01

The hierarchical MoS2 nanowires/NiCo2O4 nanosheets (MS/NCO) supercapacitor electrode materials supported on Ni foam were synthesized by a two-step hydrothermal method. The capacitance was investigated by using various electrochemical methods including cyclic voltammetry, constant-current galvanostatic charge/discharge curves and electrochemical impedance spectroscopy. The MS/NCO networks show 7 times more capacitance (7.1 F cm-2) than pure NiCo2O4 nanosheets by CV at a scan rate of 2 mV s-1. The specific capacitance of the assembled MS/NCO//active carbon (AC) asymmetric supercapacitor could reach up to 51.7 F g-1 at a current density of 1.5 A g-1. Also, the maximum energy density of 18.4 W h kg-1 at a power density of 1200.2 W kg-1 was achieved, with 98.2% specific capacitance retention after 8000 cycles. These exciting results exhibit potential application in developing energy storage devices with high energy density and high power density.

Hybrid NiS/CoO mesoporous nanosheet arrays on Ni foam for high-rate supercapacitors

NASA Astrophysics Data System (ADS)

Wu, Jianghong; Ouyang, Canbin; Dou, Shuo; Wang, Shuangyin

2015-08-01

A new hybrid of NiS/CoO porous nanosheets was synthesized on Ni foam by one-step electrodeposition method and used as an electrode for high-performance pseudocapacitance. The as-synthesized NiS/CoO porous nanosheets hybrid shows a high specific capacitance of 1054 F g-1 at a high current density of 6 A g-1, a good rate capability even at high current density (760 F g-1 at 20 A g-1) and a good long-term cycling stability (91.7% of the maximum specific capacitance after 3000 cycles). These excellent properties can be mainly attributed to the unique hierarchical porous structure with large surface area and interspaces which facilitate charge transfer and redox reaction. The enhancement in the interface contact between active material and substrate results in excellent conductivity of the electrode and a strong synergistic effect of NiS and CoO as individual constituents contributed to high capacitance of the hybrid electrode.

Hybrid NiS/CoO mesoporous nanosheet arrays on Ni foam for high-rate supercapacitors.

PubMed

Wu, Jianghong; Ouyang, Canbin; Dou, Shuo; Wang, Shuangyin

2015-08-14

A new hybrid of NiS/CoO porous nanosheets was synthesized on Ni foam by one-step electrodeposition method and used as an electrode for high-performance pseudocapacitance. The as-synthesized NiS/CoO porous nanosheets hybrid shows a high specific capacitance of 1054 F g(-1) at a high current density of 6 A g(-1), a good rate capability even at high current density (760 F g(-1) at 20 A g(-1)) and a good long-term cycling stability (91.7% of the maximum specific capacitance after 3000 cycles). These excellent properties can be mainly attributed to the unique hierarchical porous structure with large surface area and interspaces which facilitate charge transfer and redox reaction. The enhancement in the interface contact between active material and substrate results in excellent conductivity of the electrode and a strong synergistic effect of NiS and CoO as individual constituents contributed to high capacitance of the hybrid electrode.

In situ synthesized heteropoly acid/polyaniline/graphene nanocomposites to simultaneously boost both double layer- and pseudo-capacitance for supercapacitors.

PubMed

Cui, Zhiming; Guo, Chun Xian; Yuan, Weiyong; Li, Chang Ming

2012-10-05

It is challenging to simultaneously increase double layer- and pseudo-capacitance for supercapacitors. Phosphomolybdic acid/polyaniline/graphene nanocomposites (PMo(12)-PANI/GS) were prepared by using PMo(12) as a bifunctional reagent for not only well dispersing graphene for high electrochemical double layer capacitance but also in situ chemically polymerizing aniline for high pseudocapacitance, resulting in a specific capacitance of 587 F g(-1), which is ~1.5 and 6 times higher than that of PANI/GS (392 F g(-1)) and GS (103 F g(-1)), respectively. The nanocomposites also exhibit good reversibility and stability. Other kinds of heteropolyacids such as molybdovanadophosphoric acids (PMo(12-x)V(x), x = 1, 2 and 3) were also used to prepare PMo(12-x)V(x)-PANI/GS nanocomposites, also showing enhanced double layer- and pseudo-capacitance. This further proves the proposed concept to simultaneously boost both double layer- and pseudo-capacitance and demonstrates that it could be a universal approach to significantly improve the capacitance for supercapacitors.

Superior supercapacitors based on nitrogen and sulfur co-doped hierarchical porous carbon: Excellent rate capability and cycle stability

NASA Astrophysics Data System (ADS)

Zhang, Deyi; Han, Mei; Wang, Bing; Li, Yubing; Lei, Longyan; Wang, Kunjie; Wang, Yi; Zhang, Liang; Feng, Huixia

2017-08-01

Vastly improving the charge storage capability of supercapacitors without sacrificing their high power density and cycle performance would bring bright application prospect. Herein, we report a nitrogen and sulfur co-doped hierarchical porous carbon (NSHPC) with very superior capacitance performance fabricated by KOH activation of nitrogen and sulfur co-doped ordered mesoporous carbon (NSOMC). A high electrochemical double-layer (EDL) capacitance of 351 F g-1 was observed for the reported NSHPC electrodes, and the capacitance remains at 288 F g-1 even under a large current density of 20 A g-1. Besides the high specific capacitance and outstanding rate capability, symmetrical supercapacitor cell based on the NSHPC electrodes also exhibits an excellent cycling performance with 95.61% capacitance retention after 5000 times charge/discharge cycles. The large surface area caused by KOH activation (2056 m2 g-1) and high utilized surface area owing to the ideal micro/mesopores ratio (2.88), large micropores diameter (1.38 nm) and short opened micropores structure as well as the enhanced surface wettability induced by N and S heteroatoms doping and improved conductivity induced by KOH activation was found to be responsible for the very superior capacitance performance.

Copper oxide nanowires as better performance electrode material for supercapacitor application

NASA Astrophysics Data System (ADS)

Yar, A.; Dennis, J. O.; Mohamed, N. M.; Mian, M. U.; Irshad, M. I.; Mumtaz, A.

2016-11-01

Supercapacitors are highly attractive energy storage devices which are capable of delivering high power, with fast charging and long cycle life. Carbon based material rely on physical charging with less capacitance while metal oxide store charge by fast redox reaction with increased capacitance. Among metal oxide, copper oxide compounds are widely use in the form of nano and micro structures with no definite control over structure. In this work we utilized the well-controlled structure copper wires, originated from AAO template. Such well controlled structure offer better capacitance values due to easily excess of ions to the surface of wires. Performance of material was check in 3 M of potassium hydroxide (KOH). Specific capacitance (Cs) was calculated by using cyclic voltammetry (CV) and Charge discharge (CDC) test. The capacitance calculate on base on CV at 25 mV/s was 101.37 F/g while CDC showed the capacitance of 90 F/g at 2 A/g.

Robust electrodes based on coaxial TiC/C-MnO2 core/shell nanofiber arrays with excellent cycling stability for high-performance supercapacitors.

PubMed

Zhang, Xuming; Peng, Xiang; Li, Wan; Li, Limin; Gao, Biao; Wu, Guosong; Huo, Kaifu; Chu, Paul K

2015-04-17

A coaxial electrode structure composed of manganese oxide-decorated TiC/C core/shell nanofiber arrays is produced hydrothermally in a KMnO4 solution. The pristine TiC/C core/shell structure prepared on the Ti alloy substrate provides the self-sacrificing carbon shell and highly conductive TiC core, thus greatly simplifying the fabrication process without requiring an additional reduction source and conductive additive. The as-prepared electrode exhibits a high specific capacitance of 645 F g(-1) at a discharging current density of 1 A g(-1) attributable to the highly conductive TiC/C and amorphous MnO2 shell with fast ion diffusion. In the charging/discharging cycling test, the as-prepared electrode shows high stability and 99% capacity retention after 5000 cycles. Although the thermal treatment conducted on the as-prepared electrode decreases the initial capacitance, the electrode undergoes capacitance recovery through structural transformation from the crystalline cluster to layered birnessite type MnO2 nanosheets as a result of dissolution and further electrodeposition in the cycling. 96.5% of the initial capacitance is retained after 1000 cycles at high charging/discharging current density of 25 A g(-1). This study demonstrates a novel scaffold to construct MnO2 based SCs with high specific capacitance as well as excellent mechanical and cycling stability boding well for future design of high-performance MnO2-based SCs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nitrogen doped activated carbon from pea skin for high performance supercapacitor

NASA Astrophysics Data System (ADS)

Ahmed, Sultan; Ahmed, Ahsan; Rafat, M.

2018-04-01

In this work, nitrogen doped porous carbon (NDC) has been synthesized employing a facile two-step process. Firstly, carbon precursor (pea skin) was heated with melamine (acting as nitrogen source) followed by activation with KOH in different ratios. The dependence of porosity and nitrogen content on impregnation ratio was extensively studied. Other textural properties of prepared NDC sample were studied using standard techniques of material characterization. The electrochemical performance of NDC sample as an electrode was studied in two-electrode symmetric supercapacitor system. 1 M LiTFSI (lithium bis-trifluoromethanesulfonimide) solution in IL EMITFSI (1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide), was used as electrolyte. It was found that the fabricated supercapacitor cell offers high values of specific capacitance (141.1 F g‑1), specific energy (19.6 Wh kg‑1) and specific power (25.4 kW kg‑1) at current density of 1.3 A g‑1. More importantly, the fabricated supercapacitor cell shows capacitance retention of ∼75%, for more than 5000 cycles. The enhanced performance of NDC sample is primarily due to large surface area with favorable surface structure (contributing to double layer capacitance) and presence of nitrogen functionalities (contributing to pseudo-capacitance). Such important features make the synthesized NDC sample, an attractive choice for electrode material in high performance supercapacitor.

One-Pot Synthesis of Tunable Crystalline Ni3 S4 @Amorphous MoS2 Core/Shell Nanospheres for High-Performance Supercapacitors.

PubMed

Zhang, Yu; Sun, Wenping; Rui, Xianhong; Li, Bing; Tan, Hui Teng; Guo, Guilue; Madhavi, Srinivasan; Zong, Yun; Yan, Qingyu

2015-08-12

Transition metal sulfides gain much attention as electrode materials for supercapacitors due to their rich redox chemistry and high electrical conductivity. Designing hierarchical nanostructures is an efficient approach to fully utilize merits of each component. In this work, amorphous MoS(2) is firstly demonstrated to show specific capacitance 1.6 times as that of the crystalline counterpart. Then, crystalline core@amorphous shell (Ni(3)S(4)@MoS(2)) is prepared by a facile one-pot process. The diameter of the core and the thickness of the shell can be independently tuned. Taking advantages of flexible protection of amorphous shell and high capacitance of the conductive core, Ni(3)S(4) @amorphous MoS(2) nanospheres are tested as supercapacitor electrodes, which exhibit high specific capacitance of 1440.9 F g(-1) at 2 A g(-1) and a good capacitance retention of 90.7% after 3000 cycles at 10 A g(-1). This design of crystalline core@amorphous shell architecture may open up new strategies for synthesizing promising electrode materials for supercapacitors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Supercapacitors based on self-assembled graphene organogel.

PubMed

Sun, Yiqing; Wu, Qiong; Shi, Gaoquan

2011-10-14

Self-assembled graphene organogel (SGO) with 3-dimensional (3D) macrostructure was prepared by solvothermal reduction of a graphene oxide (GO) dispersion in propylene carbonate (PC). This SGO was used as an electrode material for fabricating supercapacitors with a PC electrolyte. The supercapacitor can be operated in a wide voltage range of 0-3 V and exhibits a high specific capacitance of 140 F g(-1) at a discharge current density of 1 A g(-1). Furthermore, it can still keep a specific capacitance of 90 F g(-1) at a high current density of 30 A g(-1). The maximum energy density of the SGO based supercapacitor was tested to be 43.5 Wh kg(-1), and this value is higher than those of the graphene based supercapacitors with aqueous or PC electrolytes reported previously. Furthermore, at a high discharge current density of 30 A g(-1), the energy and power densities of the supercapacitor were measured to be 15.4 Wh kg(-1) and 16,300 W kg(-1), respectively. These results indicate that the supercapacitor has a high specific capacitance and power density, and excellent rate capability.

Highly flexible binder-free core-shell nanofibrous electrode for lightweight electrochemical energy storage using recycled water bottles

NASA Astrophysics Data System (ADS)

Shi, HaoTian H.; Naguib, Hani E.

2016-08-01

The creation of a novel flexible nanocomposite fiber with conductive polymer polyaniline (PAni) coating on a polyethylene terephthalate (PET) substrate allowed for increased electrochemical performance while retaining ideal mechanical properties such as very high flexibility. Binder-free PAni-wrapped PET (PAni@PET) fiber with a core-shell structure was successfully fabricated through a novel technique. The PET nanofiber substrate was fabricated through an optimized electrospinning method, while the PAni shell was chemically polymerized onto the surface of the nanofibers. The PET substrate can be made directly from recycled PETE1 grade plastic water bottles. The resulting nanofiber with an average diameter of 121 nm ± 39 nm, with a specific surface area of 83.72 m2 g-1, led to better ionic interactions at the electrode/electrolyte interface. The PAni active layer coating was found to be 69 nm in average thickness. The specific capacitance was found to have increased dramatically from pure PAni with carbon binders. The specific capacitance was found to be 347 F g-1 at a relatively high scan rate of 10 mV s-1. The PAni/PET fiber also experienced very little degradation (4.4%) in capacitance after 1500 galvanostatic charge/discharge cycles at a specific current of 1.2 A g-1. The mesoporous structure of the PAni@PET fibrous mat also allowed for tunable capacitance by controlling the pore sizes. This novel fabrication method offers insights for the utilization of recycled PETE1 based bottles as a high performance, low cost, highly flexible supercapacitor device.

Solution growth of NiO nanosheets supported on Ni foam as high-performance electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Yan, Hailong; Zhang, Deyang; Xu, Jinyou; Lu, Yang; Liu, Yunxin; Qiu, Kangwen; Zhang, Yihe; Luo, Yongsong

2014-08-01

Well-aligned nickel oxide (NiO) nanosheets with the thickness of a few nanometers supported on a flexible substrate (Ni foam) have been fabricated by a hydrothermal approach together with a post-annealing treatment. The three-dimensional NiO nanosheets were further used as electrode materials to fabricate supercapacitors, with high specific capacitance of 943.5, 791.2, 613.5, 480, and 457.5 F g-1 at current densities of 5, 10, 15, 20, and 25 A g-1, respectively. The NiO nanosheets combined well with the substrate. When the electrode material was bended, it can still retain 91.1% of the initial capacitance after 1,200 charging/discharging cycles. Compared with Co3O4 and NiO nanostructures, the specific capacitance of NiO nanosheets is much better. These characteristics suggest that NiO nanosheet electrodes are promising for energy storage application with high power demands.

Graphene oxide - Polyvinyl alcohol nanocomposite based electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Pawar, Pranav Bhagwan; Shukla, Shobha; Saxena, Sumit

2016-07-01

Supercapacitors are high capacitive energy storage devices and find applications where rapid bursts of power are required. Thus materials offering high specific capacitance are of fundamental interest in development of these electrochemical devices. Graphene oxide based nanocomposites are mechanically robust and have interesting electronic properties. These form potential electrode materials efficient for charge storage in supercapacitors. In this perspective, we investigate low cost graphene oxide based nanocomposites as electrode material for supercapacitor. Nanocomposites of graphene oxide and polyvinyl alcohol were synthesized in solution phase by integrating graphene oxide as filler in polyvinyl alcohol matrix. Structural and optical characterizations suggest the formation of graphene oxide and polyvinyl alcohol nanocomposites. These nanocomposites were found to have high specific capacitance, were cyclable, ecofriendly and economical. Our studies suggest that nanocomposites prepared by adding 0.5% wt/wt of graphene oxide in polyvinyl alcohol can be used an efficient electrode material for supercapacitors.

Solution growth of NiO nanosheets supported on Ni foam as high-performance electrodes for supercapacitors.

PubMed

Yan, Hailong; Zhang, Deyang; Xu, Jinyou; Lu, Yang; Liu, Yunxin; Qiu, Kangwen; Zhang, Yihe; Luo, Yongsong

2014-01-01

Well-aligned nickel oxide (NiO) nanosheets with the thickness of a few nanometers supported on a flexible substrate (Ni foam) have been fabricated by a hydrothermal approach together with a post-annealing treatment. The three-dimensional NiO nanosheets were further used as electrode materials to fabricate supercapacitors, with high specific capacitance of 943.5, 791.2, 613.5, 480, and 457.5 F g(-1) at current densities of 5, 10, 15, 20, and 25 A g(-1), respectively. The NiO nanosheets combined well with the substrate. When the electrode material was bended, it can still retain 91.1% of the initial capacitance after 1,200 charging/discharging cycles. Compared with Co3O4 and NiO nanostructures, the specific capacitance of NiO nanosheets is much better. These characteristics suggest that NiO nanosheet electrodes are promising for energy storage application with high power demands.

Morphology engineering of ZnO nanostructures for high performance supercapacitors: enhanced electrochemistry of ZnO nanocones compared to ZnO nanowires.

PubMed

He, Xiaoli; Yoo, Joung Eun; Lee, Min Ho; Bae, Joonho

2017-06-16

In this work, the morphology of ZnO nanostructures is engineered to demonstrate enhanced supercapacitor characteristics of ZnO nanocones (NCs) compared to ZnO nanowires (NWs). ZnO NCs are obtained by chemically etching ZnO NWs. Electrochemical characteristics of ZnO NCs and NWs are extensively investigated to demonstrate morphology dependent capacitive performance of one dimensional ZnO nanostructures. Cyclic voltammetry measurements on these two kinds of electrodes in a three-electrode cell confirms that ZnO NCs exhibit a high specific capacitance of 378.5 F g -1 at a scan rate of 20 mV s -1 , which is almost twice that of ZnO NWs (191.5 F g -1 ). The charge-discharge and electrochemical impedance spectroscopy measurements also clearly result in enhanced capacitive performance of NCs as evidenced by higher specific capacitances and lower internal resistance. Asymmetric supercapacitors are fabricated using activated carbon (AC) as the negative electrode and ZnO NWs and NCs as positive electrodes. The ZnO NC⫽AC can deliver a maximum specific capacitance of 126 F g -1 at a current density of 1.33 A g -1 with an energy density of 25.2 W h kg -1 at the power density of 896.44 W kg -1 . In contrast, ZnO NW⫽AC displays 63% of the capacitance obtained from the ZnO NC⫽AC supercapacitor. The enhanced performance of NCs is attributed to the higher surface area of ZnO nanostructures after the morphology is altered from NWs to NCs.

Morphology engineering of ZnO nanostructures for high performance supercapacitors: enhanced electrochemistry of ZnO nanocones compared to ZnO nanowires

NASA Astrophysics Data System (ADS)

He, Xiaoli; Yoo, Joung Eun; Lee, Min Ho; Bae, Joonho

2017-06-01

In this work, the morphology of ZnO nanostructures is engineered to demonstrate enhanced supercapacitor characteristics of ZnO nanocones (NCs) compared to ZnO nanowires (NWs). ZnO NCs are obtained by chemically etching ZnO NWs. Electrochemical characteristics of ZnO NCs and NWs are extensively investigated to demonstrate morphology dependent capacitive performance of one dimensional ZnO nanostructures. Cyclic voltammetry measurements on these two kinds of electrodes in a three-electrode cell confirms that ZnO NCs exhibit a high specific capacitance of 378.5 F g-1 at a scan rate of 20 mV s-1, which is almost twice that of ZnO NWs (191.5 F g-1). The charge-discharge and electrochemical impedance spectroscopy measurements also clearly result in enhanced capacitive performance of NCs as evidenced by higher specific capacitances and lower internal resistance. Asymmetric supercapacitors are fabricated using activated carbon (AC) as the negative electrode and ZnO NWs and NCs as positive electrodes. The ZnO NC⫽AC can deliver a maximum specific capacitance of 126 F g-1 at a current density of 1.33 A g-1 with an energy density of 25.2 W h kg-1 at the power density of 896.44 W kg-1. In contrast, ZnO NW⫽AC displays 63% of the capacitance obtained from the ZnO NC⫽AC supercapacitor. The enhanced performance of NCs is attributed to the higher surface area of ZnO nanostructures after the morphology is altered from NWs to NCs.

Synthesis of carbon core–shell pore structures and their performance as supercapacitors

DOE PAGES

Ariyanto, Teguh; Dyatkin, Boris; Zhang, Gui-Rong; ...

2015-07-15

High-power supercapacitors require excellent electrolyte mobility within the pore network and high electrical conductivity for maximum capacitance and efficiency. Achieving high power typically requires sacrificing energy densities, as the latter demands a high specific surface area and narrow porosity that impedes ion transport. Here, we present a novel solution for this optimization problem: a nanostructured core–shell carbonaceous material that exhibits a microporous carbon core surrounded by a mesoporous, graphitic shell. The tunable synthesis parameters yielded a structure that features either a sharp or a gradual transition between the core and shell sections. Electrochemical supercapacitor testing using organic electrolyte revealed thatmore » these novel core–shell materials outperform carbons with homogeneous pore structures. The hybrid core–shell materials showed a combination of good capacitance retention, typical for the carbon present in the shell and high specific capacitance, typical for the core material. These materials achieved power densities in excess of 40 kW kg -1 at energy densities reaching 27 Wh kg -1.« less

Symmetric redox supercapacitor based on micro-fabrication with three-dimensional polypyrrole electrodes

NASA Astrophysics Data System (ADS)

Sun, Wei; Zheng, Ruilin; Chen, Xuyuan

To achieve higher energy density and power density, we have designed and fabricated a symmetric redox supercapacitor based on microelectromechanical system (MEMS) technologies. The supercapacitor consists of a three-dimensional (3D) microstructure on silicon substrate micromachined by high-aspect-ratio deep reactive ion etching (DRIE) method, two sputtered Ti current collectors and two electrochemical polymerized polypyrrole (PPy) films as electrodes. Electrochemical tests, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatical charge/discharge methods have been carried out on the single PPy electrodes and the symmetric supercapacitor in different electrolytes. The specific capacitance (capacitance per unit footprint area) and specific power (power per unit footprint area) of the PPy electrodes and symmetric supercapacitor can be calculated from the electrochemical test data. It is found that NaCl solution is a good electrolyte for the polymerized PPy electrodes. In NaCl electrolyte, single PPy electrodes exhibit 0.128 F cm -2 specific capacitance and 1.28 mW cm -2 specific power at 20 mV s -1 scan rate. The symmetric supercapacitor presents 0.056 F cm -2 specific capacitance and 0.56 mW cm -2 specific power at 20 mV s -1 scan rate.

Hierarchical NiCo2 S4 Nanotube@NiCo2 S4 Nanosheet Arrays on Ni Foam for High-Performance Supercapacitors.

PubMed

Chen, Haichao; Chen, Si; Shao, Hongyan; Li, Chao; Fan, Meiqiang; Chen, Da; Tian, Guanglei; Shu, Kangying

2016-01-01

Hierarchical NiCo2 S4 nanotube@NiCo2 S4 nanosheet arrays on Ni foam have been successfully synthesized. Owing to the unique hierarchical structure, enhanced capacitive performance can be attained. A specific capacitance up to 4.38 F cm(-2) is attained at 5 mA cm(-2) , which is much higher than the specific capacitance values of NiCo2 O4 nanosheet arrays, NiCo2 S4 nanosheet arrays and NiCo2 S4 nanotube arrays on Ni foam. The hierarchical NiCo2 S4 nanostructure shows superior cycling stability; after 5000 cycles, the specific capacitance still maintains 3.5 F cm(-2) . In addition, through the morphology and crystal structure measurement after cycling stability test, it is found that the NiCo2 S4 electroactive materials are gradually corroded; however, the NiCo2 S4 phase can still be well-maintained. Our results show that hierarchical NiCo2 S4 nanostructures are suitable electroactive materials for high performance supercapacitors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid MnO2/carbon nanotube-VN/carbon nanotube supercapacitors

NASA Astrophysics Data System (ADS)

Su, Y.; Zhitomirsky, I.

2014-12-01

Composite materials, containing fibrous VN nanoparticles and multiwalled carbon nanotubes (MWCNT) are prepared by a chemical method for application in electrochemical supercapacitors. We demonstrate for the first time that VN-MWCNT electrodes exhibit good capacitive behavior in 0.5 M Na2SO4 electrolyte in a negative voltage window of 0.9 V. Quartz crystal microbalance studies provide an insight into the mechanism of charge storage. Composite VN-MWCNT materials show significant improvement in capacitance, compared to individual VN and MWCNT materials. Testing results indicate that VN-MWCNT electrodes exhibit high specific capacitance at high mass loadings in the range of 10-30 mg cm-2, good capacitance retention at scan rates in the range of 2-200 mV s-1 and good cycling stability. The highest specific capacitance of 160 F g-1 is achieved at a scan rate of 2 mV s-1. The new findings open a new and promising strategy in the fabrication of hybrid devices based on VN. The proof-of-principle is demonstrated by the fabrication of hybrid supercapacitor devices based on VN-MWCNT negative electrodes and MnO2 -MWCNT positive electrodes with voltage window of 1.8 V in aqueous 0.5 M Na2SO4 electrolyte. The hybrid VN-MWCNT/MnO2-MWCNT supercapacitor cells show promising capacitive and power-energy characteristics.

Hydrothermal Synthesis and Electrochemical Properties of Spherical α-MnO2 for Supercapacitors.

PubMed

Chen, Ya; Qin, Wenqing; Fan, Ruijuan; Wang, Jiawei; Chen, Baizhen

2015-12-01

In the present work, spherical α-MnO2 with a high specific capacitance was synthesized by a two-step hydrothermal route. MnCO3 precursors were first prepared by a common hydrothermal method, and then converted to α-MnO2 via a hydrothermal reaction between the precursors and KMnO4 solutions. The effects of hydrothermal temperature on the morphology, crystal structure and specific area of the MnO2 were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET measurements. The electrochemical capacitive properties of the manganese dioxides with different morphologies and structures were evaluated by cyclic voltammetry and galvonostatic charge-discharge tests. The results showed that the temperature in the second hydrothermal step had prominent impact on the capacitive properties of a-MnO2. The MnO2 synthesized at 150 *C exhibited a highest specific capacitance of 328.4 Fx g(-1) at a charge-discharge current density of 100 mA x g(-1).

Comparison of carbon onions and carbon blacks as conductive additives for carbon supercapacitors in organic electrolytes

NASA Astrophysics Data System (ADS)

Jäckel, N.; Weingarth, D.; Zeiger, M.; Aslan, M.; Grobelsek, I.; Presser, V.

2014-12-01

This study investigates carbon onions (∼400 m2 g-1) as a conductive additive for supercapacitor electrodes of activated carbon and compares their performance with carbon black with high or low internal surface area. We provide a study of the electrical conductivity and electrochemical behavior between 2.5 and 20 mass% addition of each of these three additives to activated carbon. Structural characterization shows that the density of the resulting film electrodes depends on the degree of agglomeration and the amount of additive. Addition of low surface area carbon black (∼80 m2 g-1) enhances the power handling of carbon electrodes but significantly lowers the specific capacitance even when adding small amounts of carbon black. A much lower decrease in specific capacitance is observed for carbon onions and the best values are seen for carbon black with a high surface area (∼1390 m2 g-1). The overall performance benefits from the addition of any of the studied additives only at either high scan rates and/or electrolytes with high ion mobility. Normalization to the volume shows a severe decrease in volumetric capacitance and only at high current densities nearing 10 A g-1 we can see an improvement of the electrode capacitance.

A facile synthesis of reduced holey graphene oxide for supercapacitors.

PubMed

Hu, Xinjun; Bai, Dongchen; Wu, Yiqi; Chen, Songbo; Ma, Yu; Lu, Yue; Chao, Yuanzhi; Bai, Yongxiao

2017-12-12

Hydroxyl radicals (˙OH) generated from a UV/O 3 solution reaction is used to efficiently etch graphene oxide nanosheets under moderate conditions. Reduced holey graphene oxide is directly used as a supercapacitor electrode material and exhibits high specific capacitance (224 F g -1 at a current density of 1 A g -1 ) and high volumetric capacitance (up to 206 F cm -3 ).

Controllable in situ synthesis of epsilon manganese dioxide hollow structure/RGO nanocomposites for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Lin, Mei; Chen, Bolei; Wu, Xiao; Qian, Jiasheng; Fei, Linfeng; Lu, Wei; Chan, Lai Wa Helen; Yuan, Jikang

2016-01-01

Well-organized epsilon-MnO2 hollow spheres/reduced graphene oxide (MnO2HS/RGO) composites have been successfully constructed via a facile and one-pot synthetic route. The ε-MnO2 hollow spheres with the diameter of ~500 nm were grown in situ with homogeneous distribution on both sides of graphene oxide (GO) sheets in aqueous suspensions. The formation mechanism of the MnO2HS/RGO composites has been systematically investigated, and a high specific capacitance and good cycling capability were achieved on using the composites as supercapacitors. The galvanostatic charge/discharge curves show a specific capacitance of 471.5 F g-1 at 0.8 A g-1. The hollow structures of ε-MnO2 and the crumpled RGO sheets can enhance the electroactive surface area and improve the electrical conductivity, thus further facilitating the charge transport. The MnO2HS/RGO composite exhibits a high capacitance of 272 F g-1 at 3 A g-1 (92% retention) even after 1000 cycles. The prominent electrochemical performance might be attributed to the combination of the pseudo-capacitance of the MnO2 nanospheres with a hollow structure and to the good electrical conductivity of the RGO sheets. This work explores a new concept in designing metal oxides/RGO composites as electrode materials.Well-organized epsilon-MnO2 hollow spheres/reduced graphene oxide (MnO2HS/RGO) composites have been successfully constructed via a facile and one-pot synthetic route. The ε-MnO2 hollow spheres with the diameter of ~500 nm were grown in situ with homogeneous distribution on both sides of graphene oxide (GO) sheets in aqueous suspensions. The formation mechanism of the MnO2HS/RGO composites has been systematically investigated, and a high specific capacitance and good cycling capability were achieved on using the composites as supercapacitors. The galvanostatic charge/discharge curves show a specific capacitance of 471.5 F g-1 at 0.8 A g-1. The hollow structures of ε-MnO2 and the crumpled RGO sheets can enhance the electroactive surface area and improve the electrical conductivity, thus further facilitating the charge transport. The MnO2HS/RGO composite exhibits a high capacitance of 272 F g-1 at 3 A g-1 (92% retention) even after 1000 cycles. The prominent electrochemical performance might be attributed to the combination of the pseudo-capacitance of the MnO2 nanospheres with a hollow structure and to the good electrical conductivity of the RGO sheets. This work explores a new concept in designing metal oxides/RGO composites as electrode materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07900d

Effects of pore structure and electrolyte on the capacitive characteristics of steam- and KOH-activated carbons for supercapacitors

NASA Astrophysics Data System (ADS)

Wu, Feng-Chin; Tseng, Ru-Ling; Hu, Chi-Chang; Wang, Chen-Ching

Four kinds of activated carbons (denoted as ACs) with specific surface area of ca. 1050 m 2 g -1 were fabricated from fir wood and pistachio shell by means of steam activation or chemical activation with KOH. Pore structures of ACs were characterized by a t-plot method based on N 2 adsorption isotherms. The amount of mesopores within KOH-activated carbons ranged from 9.2 to 15.3% while 33.3-49.5% of mesopores were obtained for the steam-activated carbons. The pore structure, surface functional groups, and raw materials of ACs, as well as pH and the supporting electrolyte were also found to be significant factors determining the capacitive characteristics of ACs. The excellent capacitive characteristics in both acidic and neutral media and the weak dependence of the specific capacitance on the scan rate of cyclic voltammetry (CV) for the ACs derived from the pistachio shell with steam activation (denoted as P-H 2O-AC) revealed their promising potential in the application of supercapacitors. The ACs derived from fir wood with KOH activation (denoted as F-KOH-AC), on the other hand, showed the best capacitive performance in H 2SO 4 due to excellent reversibility and high specific capacitance (180 F g -1 measured at 10 mV s -1), which is obviously larger than 100 F g -1 (a typical value of activated carbons with specific surface areas equal to/above 1000 m 2 g -1).

Ionic Liquids as Electrolytes for Electrochemical Double-Layer Capacitors: Structures that Optimize Specific Energy.

PubMed

Mousavi, Maral P S; Wilson, Benjamin E; Kashefolgheta, Sadra; Anderson, Evan L; He, Siyao; Bühlmann, Philippe; Stein, Andreas

2016-02-10

Key parameters that influence the specific energy of electrochemical double-layer capacitors (EDLCs) are the double-layer capacitance and the operating potential of the cell. The operating potential of the cell is generally limited by the electrochemical window of the electrolyte solution, that is, the range of applied voltages within which the electrolyte or solvent is not reduced or oxidized. Ionic liquids are of interest as electrolytes for EDLCs because they offer relatively wide potential windows. Here, we provide a systematic study of the influence of the physical properties of ionic liquid electrolytes on the electrochemical stability and electrochemical performance (double-layer capacitance, specific energy) of EDLCs that employ a mesoporous carbon model electrode with uniform, highly interconnected mesopores (3DOm carbon). Several ionic liquids with structurally diverse anions (tetrafluoroborate, trifluoromethanesulfonate, trifluoromethanesulfonimide) and cations (imidazolium, ammonium, pyridinium, piperidinium, and pyrrolidinium) were investigated. We show that the cation size has a significant effect on the electrolyte viscosity and conductivity, as well as the capacitance of EDLCs. Imidazolium- and pyridinium-based ionic liquids provide the highest cell capacitance, and ammonium-based ionic liquids offer potential windows much larger than imidazolium and pyridinium ionic liquids. Increasing the chain length of the alkyl substituents in 1-alkyl-3-methylimidazolium trifluoromethanesulfonimide does not widen the potential window of the ionic liquid. We identified the ionic liquids that maximize the specific energies of EDLCs through the combined effects of their potential windows and the double-layer capacitance. The highest specific energies are obtained with ionic liquid electrolytes that possess moderate electrochemical stability, small ionic volumes, low viscosity, and hence high conductivity, the best performing ionic liquid tested being 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

High-Surface-Area Nitrogen-Doped Reduced Graphene Oxide for Electric Double-Layer Capacitors.

PubMed

Youn, Hee-Chang; Bak, Seong-Min; Kim, Myeong-Seong; Jaye, Cherno; Fischer, Daniel A; Lee, Chang-Wook; Yang, Xiao-Qing; Roh, Kwang Chul; Kim, Kwang-Bum

2015-06-08

A two-step method consisting of solid-state microwave irradiation and heat treatment under NH3 gas was used to prepare nitrogen-doped reduced graphene oxide (N-RGO) with a high specific surface area (1007 m(2)  g(-1) ), high electrical conductivity (1532 S m(-1) ), and low oxygen content (1.5 wt %) for electrical double-layer capacitor applications. The specific capacitance of N-RGO was 291 F g(-1) at a current density of 1 A g(-1) , and a capacitance of 261 F g(-1) was retained at 50 A g(-1) , which indicated a very good rate capability. N-RGO also showed excellent cycling stability and preserved 96 % of the initial specific capacitance after 100 000 cycles. Near-edge X-ray absorption fine-structure spectroscopy results provided evidenced for the recovery of π conjugation in the carbon networks with the removal of oxygenated groups and revealed chemical bonding of the nitrogen atoms in N-RGO. The good electrochemical performance of N-RGO is attributed to its high surface area, high electrical conductivity, and low oxygen content. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facile synthesis of NiS anchored carbon nanofibers for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Jinling; Zhang, Li; Xu, Guancheng; Sun, Zhipeng; Zhang, Chi; Ma, Xin; Qi, Chunling; Zhang, Lu; Jia, Dianzeng

2018-03-01

Transition metal sulfide compounds with carbon materials are promising for high-performance supercapacitors. Carbon nanofibers (CNFs) wrapped with NiS nanoparticles were herein obtained through electrospinning and calcination. NiS nanoparticles in composite nanofibers are covered by a layer of graphitic carbon, which not only increase the conductivity but also provide active regions for nanoparticle growth to prevent aggregation. The CNFs-NiS electrode has high specific capacity of 177.1 mAh g-1 at 1 A g-1 (0.41 mAh cm-2 at a current density of 2.3 mA cm-2) and long-term cycling stability, with 88.7% capacitance retention after 5000 cycles. The excellent electrochemical activity may be attributed to the accessible specific surface, unique porous structure of CNFs and high specific capacitance of NiS. In addition, the asymmetric supercapacitor has an enhanced volumetric energy density of 13.32 mWh cm-3 at a volumetric power density of 180 mW cm-3 and high cycling stability, with 89.5% capacitance retention after 5000 cycles. It also successfully lights up a light-emitting diode. The CNFs-NiS composite has significant potential applications in supercapacitor.

An Approach to Preparing Ni-P with Different Phases for Use as Supercapacitor Electrode Materials.

PubMed

Wang, Dan; Kong, Ling-Bin; Liu, Mao-Cheng; Luo, Yong-Chun; Kang, Long

2015-12-01

Herein, we describe a simple two-step approach to prepare nickel phosphide with different phases, such as Ni2 P and Ni5 P4 , to explain the influence of material microstructure and electrical conductivity on electrochemical performance. In this approach, we first prepared a Ni-P precursor through a ball milling process, then controlled the synthesis of either Ni2 P or Ni5 P4 by the annealing method. The as-prepared Ni2 P and Ni5 P4 are investigated as supercapacitor electrode materials for potential energy storage applications. The Ni2 P exhibits a high specific capacitance of 843.25 F g(-1) , whereas the specific capacitance of Ni5 P4 is 801.5 F g(-1) . Ni2 P possesses better cycle stability and rate capability than Ni5 P4 . In addition, the Fe2 O3 //Ni2 P supercapacitor displays a high energy density of 35.5 Wh kg(-1) at a power density of 400 W kg(-1) and long cycle stability with a specific capacitance retention rate of 96 % after 1000 cycles, whereas the Fe2 O3 //Ni5 P4 supercapacitor exhibits a high energy density of 29.8 Wh kg(-1) at a power density of 400 W kg(-1) and a specific capacitance retention rate of 86 % after 1000 cycles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nitrogen-doped ordered mesoporous carbon with a high surface area, synthesized through organic-inorganic coassembly, and its application in supercapacitors.

PubMed

Song, Yanfang; Li, Li; Wang, Yonggang; Wang, Congxiao; Guo, Zaipin; Xia, Yongyao

2014-07-21

A new nitrogen-doped ordered mesoporous carbon (N-doped OMC) is synthesized by using an organic-inorganic coassembly method, in which resol is used as the carbon precursor, dicyandiamide as the nitrogen precursor, silicate oligomers as the inorganic precursors, and F127 as the soft template. The N-doped OMC possesses a surface area as high as 1374 m(2)  g(-1) and a large pore size of 7.4 nm. As an electrode material for supercapacitors, the obtained carbon exhibits excellent cycling stability and delivers a reversible specific capacitance as high as 308 F g(-1) in 1 mol L(-1) H(2)SO(4) aqueous electrolyte, of which 58 % of the capacity is due to pseudo-capacitance. The large specific capacitance is attributed to proper pore size distributions, large surface area, and high nitrogen content. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Layered conductive polymer on nylon membrane templates for high performance, thin-film supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Shi, HaoTian Harvey; Naguib, Hani E.

2016-04-01

Flexible Thin-film Electrochemical Capacitors (ECs) are emerging technology that plays an important role as energy supply for various electronics system for both present era and the future. Intrinsically conductive polymers (ICPs) are promising pseudo-capacitive materials as they feature both good electrical conductivity and high specific capacitance. This study focuses on the construction and characterization of ultra-high surface area porous electrodes based on coating of nano-sized conductive polymer materials on nylon membrane templates. Herein, a novel nano-engineered electrode material based on nylon membranes was presented, which allows the creation of super-capacitor devices that is capable of delivering competitive performance, while maintaining desirable mechanical characteristics. With the formation of a highly conductive network with the polyaniline nano-layer, the electrical conductivity was also increased dramatically to facilitate the charge transfer process. Cyclic voltammetry and specific capacitance results showed promising application of this type of composite materials for future smart textile applications.

Manganese oxide nanowires wrapped with nitrogen doped carbon layers for high performance supercapacitors.

PubMed

Li, Ying; Mei, Yuan; Zhang, Lin-Qun; Wang, Jian-Hai; Liu, An-Ran; Zhang, Yuan-Jian; Liu, Song-Qin

2015-10-01

In this study, manganese oxide nanowires wrapped by nitrogen-doped carbon layers (MnO(x)@NCs) were prepared by carbonization of poly(o-phenylenediamine) layer coated onto MnO2 nanowires for high performance supercapacitors. The component and structure of the MnO(x)@NCs were controlled through carbonization procedure under different temperatures. Results demonstrated that this composite combined the high conductivity and high specific surface area of nitrogen-doped carbon layers with the high pseudo-capacitance of manganese oxide nanowires. The as-prepared MnO(x)@NCs exhibited superior capacitive properties in 1 M Na2SO4 aqueous solution, such as high conductivity (4.167×10(-3) S cm(-1)), high specific capacitance (269 F g(-1) at 10 mV s(-1)) and long cycle life (134 F g(-1) after 1200 cycles at a scan rate of 50 mV s(-1)). It is reckoned that the present novel hybrid nanowires can serve as a promising electrode material for supercapacitors and other electrochemical devices. Copyright © 2015 Elsevier Inc. All rights reserved.

Highly conductive porous Na-embedded carbon nanowalls for high-performance capacitive deionization

NASA Astrophysics Data System (ADS)

Chang, Liang; Hu, Yun Hang

2018-05-01

Highly conductive porous Na-embedded carbon nanowalls (Na@C), which were recently invented, have exhibited excellent performance for dye-sensitized solar cells and electric double-layer capacitors. In this work, Na@C was demonstrated as an excellent electrode material for capacitive deionization (CDI). In a three-electrode configuration system, the specific capacity of the Na@C electrodes can achieve 306.4 F/g at current density of 0.2 A/g in 1 M NaCl, which is higher than that (235.2 F/g) of activated carbon (AC) electrodes. Furthermore, a high electrosorption capacity of 8.75 mg g-1 in 100 mg/L NaCl was obtained with the Na@C electrodes in a batch-mode capacitive deionization cell. It exceeds the electrosorption capacity (4.08 mg g-1) of AC electrodes. The Na@C electrode also showed a promising cycle stability. The excellent performance of Na@C electrode for capacitive deionization (CDI) can be attributed to its high electrical conductivity and large accessible surface area.

Asymmetric supercapacitors based on electrospun carbon nanofiber/sodium-pre-intercalated manganese oxide electrodes with high power and energy densities

NASA Astrophysics Data System (ADS)

Lin, Sheng-Chi; Lu, Yi-Ting; Chien, Yu-An; Wang, Jeng-An; Chen, Po-Yu; Ma, Chen-Chi M.; Hu, Chi-Chang

2018-07-01

The sodium-pre-intercalated δ-MnO2 is in-situ grown on carbon nanofiber via a simple, one-step method for the application of asymmetric supercapacitors. The pre-intercalation of Na ions into the layered structure of δ-MnO2 reduces the crystallinity, beneficial to Na+ diffusion into/out the interlayer structure and pseudocapacitive utilization of MnO2. This NaxMnO2@CNF nanocomposite with desirable pseudo-capacitance from δ-NaxMnO2 and high electric conductivity from CNF network shows a high specific capacitance of 321 F g-1 at 1 A g-1 with ca. 75.2% capacitance retention from 1 to 32 A g-1. An ASC cell consisting of this nanocomposite and activated carbon as the positive and negative electrodes can be reversibly charged and discharged to a cell voltage of 2.0 V in 1 M Na2SO4 and 4 mM NaHCO3 with specific energy and power of 21 Wh kg-1 and 1 kW kg-1, respectively. This ASC also shows excellent cell capacitance retention (7% decay) in the 2 V, 10,000-cycle stability test, revealing superior performance.

High-Performance Flexible Asymmetric Supercapacitor Based on CoAl-LDH and rGO Electrodes

NASA Astrophysics Data System (ADS)

Li, Shuoshuo; Cheng, Pengpeng; Luo, Jiaxian; Zhou, Dan; Xu, Weiming; Li, Jingwei; Li, Ruchun; Yuan, Dingsheng

2017-07-01

A flexible asymmetric supercapacitor (ASC) based on a CoAl-layered double hydroxide (CoAl-LDH) electrode and a reduced graphene oxide (rGO) electrode was successfully fabricated. The CoAl-LDH electrode as a positive electrode was synthesized by directly growing CoAl-LDH nanosheet arrays on a carbon cloth (CC) through a facile hydrothermal method, and it delivered a specific capacitance of 616.9 F g-1 at a current density of 1 A g-1. The rGO electrode as a negative electrode was synthesized by coating rGO on the CC via a simple dip-coating method and revealed a specific capacitance of 110.0 F g-1 at a current density of 2 A g-1. Ultimately, the advanced ASC offered a broad voltage window (1.7 V) and exhibited a high superficial capacitance of 1.77 F cm-2 at 2 mA cm-2 and a high energy density of 0.71 mWh cm-2 at a power density of 17.05 mW cm-2, along with an excellent cycle stability (92.9% capacitance retention over 8000 charge-discharge cycles).

Facile synthesis of amorphous FeOOH/MnO2 composites as screen-printed electrode materials for all-printed solid-state flexible supercapacitors

NASA Astrophysics Data System (ADS)

Lu, Qiang; Liu, Li; Yang, Shuanglei; Liu, Jun; Tian, Qingyong; Yao, Weijing; Xue, Qingwen; Li, Mengxiao; Wu, Wei

2017-09-01

More convenience and intelligence life lead by flexible/wearable electronics requires innovation and hommization of power sources. Here, amorphous FeOOH/MnO2 composite as screen-printed electrode materials for supercapacitors (SCs) is synthesized by a facile method, and solid-state flexible SCs with aesthetic design are fabricated by fully screen-printed process on different substrates, including PET, paper and textile. The amorphous FeOOH/MnO2 composite shows a high specific capacitance and a good rate capability (350.2 F g-1 at a current density of 0.5 A g-1 and 159.5 F g-1 at 20 A g-1). It also possesses 95.6% capacitance retention even after 10 000 cycles. Moreover, the all-printed solid-state flexible SC device exhibits a high area specific capacitance of 5.7 mF cm-2 and 80% capacitance retention even after 2000 cycles. It also shows high mechanical flexibility. Simultaneously, these printed SCs on different substrates in series are capable to light up a 1.9 V yellow light emitting diode (LED), even after bending and stretching.

Hierarchical porous nickel oxide-carbon nanotubes as advanced pseudocapacitor materials for supercapacitors

NASA Astrophysics Data System (ADS)

Su, Aldwin D.; Zhang, Xiang; Rinaldi, Ali; Nguyen, Son T.; Liu, Huihui; Lei, Zhibin; Lu, Li; Duong, Hai M.

2013-03-01

Hierarchical porous carbon anode and metal oxide cathode are promising for supercapacitor with both high energy density and high power density. This Letter uses NiO and commercial carbon nanotubes (CNTs) as electrode materials for electrochemical capacitors with high energy storage capacities. Experimental results show that the specific capacitance of the electrode materials for 10%, 30% and 50% CNTs are 279, 242 and 112 F/g, respectively in an aqueous 1 M KOH electrolyte at a charge rate of 0.56 A/g. The maximum specific capacitance is 328 F/g at a charge rate of 0.33 A/g.

Microbial fuel cell as a biocapacitor by using pseudo-capacitive anode materials

NASA Astrophysics Data System (ADS)

Lv, Zhisheng; Xie, Daohai; Li, Fusheng; Hu, Yun; Wei, Chaohai; Feng, Chunhua

2014-01-01

Here, we report that the microbial fuel cell (MFC) containing pseudo-capacitive anode materials such as polypyrrole (PPy)/9,10-anthraquinone-2-sulfonic acid sodium salt (AQS) composite films and RuO2 nanoparticles can function as a biocapacitor, able to store bioelectrons generated from microbial oxidation of substrate and release the accumulated charge upon requirement. Influences of the specific capacitance of the PPy/AQS- and RuO2-modified carbon felt anodes on the extent of accumulated charge are examined. Results show that increasing anode capacitance is responsible for the increases in the amount of electrons stored and released, and thereby leading to more energy stored and average power dissipated. The long-term charging-discharging tests indicate that the RuO2-modified biocapacitor with a specific capacitance of 3.74 F cm-2 exhibits 6% loss in the amount of released charge over 10 cycles for one-month operation, and 40% loss over 60 cycles for six-month operation. Our findings suggest that the MFC anode incorporating pseudo-capacitive materials shows potential for storing energy from waste organic matter and releasing in a short time of high power to the electronic device.

Effect of ion concentration, solution and membrane permittivity on electric energy storage and capacitance.

PubMed

Tajparast, Mohammad; Glavinović, Mladen I

2018-06-06

Bio-membranes as capacitors store electric energy, but their permittivity is low whereas the permittivity of surrounding solution is high. To evaluate the effective capacitance of the membrane/solution system and determine the electric energy stored within the membrane and in the solution, we estimated their electric variables using Poisson-Nernst-Planck simulations. We calculated membrane and solution capacitances from stored electric energy. The effective capacitance was calculated by fitting a six-capacitance model to charges (fixed and ion) and associated potentials, because it cannot be considered as a result of membrane and solution capacitance in series. The electric energy stored within the membrane (typically much smaller than that in the solution), depends on the membrane permittivity, but also on the external electric field, surface charge density, water permittivity and ion concentration. The effect on capacitances is more specific. Solution capacitance rises with greater solution permittivity or ion concentration, but the membrane capacitance (much smaller than solution capacitance) is only influenced by its permittivity. Interestingly, the effective capacitance is independent of membrane or solution permittivity, but rises as the ion concentration increases and surface charge becomes positive. Experimental estimates of membrane capacitance are thus not necessarily a reliable index of its surface area. Copyright © 2018. Published by Elsevier B.V.

Functionalized graphene hydrogel-based high-performance supercapacitors.

PubMed

Xu, Yuxi; Lin, Zhaoyang; Huang, Xiaoqing; Wang, Yang; Huang, Yu; Duan, Xiangfeng

2013-10-25

Functionalized graphene hydrogels are prepared by a one-step low-temperature reduction process and exhibit ultrahigh specific capacitances and excellent cycling stability in the aqueous electrolyte. Flexible solid-state supercapacitors based on functionalized graphene hydrogels are demonstrated with superior capacitive performances and extraordinary mechanical flexibility. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Porous NiCo2O4 nanosheets/reduced graphene oxide composite: facile synthesis and excellent capacitive performance for supercapacitors.

PubMed

Ma, Lianbo; Shen, Xiaoping; Ji, Zhenyuan; Cai, Xiaoqing; Zhu, Guoxing; Chen, Kangmin

2015-02-15

A composite with porous NiCo2O4 nanosheets attached on reduced graphene oxide (RGO) sheets is synthesized through a facile solution-based method combined with a simple thermal annealing process. The capacitive performances of the as-prepared NiCo2O4/RGO (NCG) composites as electrode materials are investigated. It is found that the NCG composites exhibit a high specific capacitance up to 1186.3 F g(-1) at the current density of 0.5 A g(-1), and superior cycling stability with about 97% of the initial capacitance after 100 cycles. The greatly enhanced capacitive performance of the NCG electrode can be attributed to the existence of RGO support, which serves as both conductive channels and active interface. The approach used in the synthesis provides a facile route for preparing graphene-binary metal oxide electrode materials. The remarkable capacitive performance of NCG composites will undoubtedly make them be attractive for high performance energy storage applications. Copyright © 2014 Elsevier Inc. All rights reserved.

Nitrogen-doped graphitic hierarchically porous carbon nanofibers obtained via bimetallic-coordination organic framework modification and their application in supercapacitors.

PubMed

Yao, Yuechao; Liu, Peng; Li, Xiaoyan; Zeng, Shaozhong; Lan, Tongbin; Huang, Haitao; Zeng, Xierong; Zou, Jizhao

2018-05-17

Herein, N-doped graphitic hierarchically porous carbon nanofibers (NGHPCF) were prepared by electrospinning the composite of bimetallic-coordination metal-organic frameworks and polyacrylonitrile, followed by a pyrolysis and acid wash process. Control over the N content, specific surface area, and degree of graphitization of NGHPCF materials has been realized by adjusting the Co/Zn metal coordination content as well as the pyrolysis temperature. The obtained NGHPCF with a high specific surface area (623 m2 g-1) and nitrogen content (13.83 wt%) exhibit a high capacitance of 326 F g-1 at 0.5 A g-1. In addition, the capacitance of 170 F g-1 is still maintained at a high current density (40 A g-1); this indicates a high capacitance retention capability. Furthermore, a superb energy density (9.61 W h kg-1) is obtained with a high power density (62.4 W kg-1) using an organic electrolyte. These results fully illustrate that the prepared NGHPCF binder-free electrodes are promising candidates for high-performance supercapacitors.

Hydrogenated TiO2 nanotube arrays for supercapacitors.

PubMed

Lu, Xihong; Wang, Gongming; Zhai, Teng; Yu, Minghao; Gan, Jiayong; Tong, Yexiang; Li, Yat

2012-03-14

We report a new and general strategy for improving the capacitive properties of TiO(2) materials for supercapacitors, involving the synthesis of hydrogenated TiO(2) nanotube arrays (NTAs). The hydrogenated TiO(2) (denoted as H-TiO(2)) were obtained by calcination of anodized TiO(2) NTAs in hydrogen atmosphere in a range of temperatures between 300 to 600 °C. The H-TiO(2) NTAs prepared at 400 °C yields the largest specific capacitance of 3.24 mF cm(-2) at a scan rate of 100 mV s(-1), which is 40 times higher than the capacitance obtained from air-annealed TiO(2) NTAs at the same conditions. Importantly, H-TiO(2) NTAs also show remarkable rate capability with 68% areal capacitance retained when the scan rate increase from 10 to 1000 mV s(-1), as well as outstanding long-term cycling stability with only 3.1% reduction of initial specific capacitance after 10,000 cycles. The prominent electrochemical capacitive properties of H-TiO(2) are attributed to the enhanced carrier density and increased density of hydroxyl group on TiO(2) surface, as a result of hydrogenation. Furthermore, we demonstrate that H-TiO(2) NTAs is a good scaffold to support MnO(2) nanoparticles. The capacitor electrodes made by electrochemical deposition of MnO(2) nanoparticles on H-TiO(2) NTAs achieve a remarkable specific capacitance of 912 F g(-1) at a scan rate of 10 mV s(-1) (based on the mass of MnO(2)). The ability to improve the capacitive properties of TiO(2) electrode materials should open up new opportunities for high-performance supercapacitors. © 2012 American Chemical Society

Design of 3D Graphene-Oxide Spheres and Their Derived Hierarchical Porous Structures for High Performance Supercapacitors.

PubMed

Li, Zhuangnan; Gadipelli, Srinivas; Yang, Yuchen; Guo, Zhengxiao

2017-11-01

Graphene-oxide (GO) based porous structures are highly desirable for supercapacitors, as the charge storage and transfer can be enhanced by advancement in the synthesis. An effective route is presented of, first, synthesis of three-dimensional (3D) assembly of GO sheets in a spherical architecture (GOS) by flash-freezing of GO dispersion, and then development of hierarchical porous graphene (HPG) networks by facile thermal-shock reduction of GOS. This leads to a superior gravimetric specific capacitance of ≈306 F g -1 at 1.0 A g -1 , with a capacitance retention of 93% after 10 000 cycles. The values represent a significant capacitance enhancement by 30-50% compared with the GO powder equivalent, and are among the highest reported for GO-based structures from different chemical reduction routes. Furthermore, a solid-state flexible supercapacitor is fabricated by constructing the HPG with polymer gel electrolyte, exhibiting an excellent areal specific capacitance of ≈220 mF cm -2 at 1.0 mA cm -2 with exceptional cyclic stability. The work reveals a facile but efficient synthesis approach of GO-based materials to enhance the capacitive energy storage. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Activated Porous Carbon Spheres with Customized Mesopores through Assembly of Diblock Copolymers for Electrochemical Capacitor.

PubMed

Tang, Jing; Wang, Jie; Shrestha, Lok Kumar; Hossain, Md Shahriar A; Alothman, Zeid Abdullah; Yamauchi, Yusuke; Ariga, Katsuhiko

2017-06-07

A series of porous carbon spheres with precisely adjustable mesopores (4-16 nm), high specific surface area (SSA, ∼2000 m 2 g -1 ), and submicrometer particle size (∼300 nm) was synthesized through a facile coassembly of diblock polymer micelles with a nontoxic dopamine source and a common postactivation process. The mesopore size can be controlled by the diblock polymer, polystyrene-block-poly(ethylene oxide) (PS-b-PEO) templates, and has an almost linear dependence on the square root of the degree of polymerization of the PS blocks. These advantageous structural properties make the product a promising electrode material for electrochemical capacitors. The electrochemical capacitive performance was studied carefully by using symmetrical cells in a typical organic electrolyte of 1 M tetraethylammonium tetrafluoroborate/acetonitrile (TEA BF 4 /AN) or in an ionic liquid electrolyte of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF 4 ), displaying a high specific capacitance of 111 and 170 F g -1 at 1 A g -1 , respectively. The impacts of pore size distribution on the capacitance performance were thoroughly investigated. It was revealed that large mesopores and a relatively low ratio of micropores are ideal for realizing high SSA-normalized capacitance. These results provide us with a simple and reliable way to screen future porous carbon materials for electrochemical capacitors and encourage researchers to design porous carbon with high specific surface area, large mesopores, and a moderate proportion of micropores.

Synthesis and Characterization of Self-Standing and Highly Flexible δ-MnO2@CNTs/CNTs Composite Films for Direct Use of Supercapacitor Electrodes.

PubMed

Wu, Peng; Cheng, Shuang; Yang, Lufeng; Lin, Zhiqiang; Gui, Xuchun; Ou, Xing; Zhou, Jun; Yao, Minghai; Wang, Mengkun; Zhu, Yuanyuan; Liu, Meilin

2016-09-14

Self-standing and flexible films worked as pseudocapacitor electrodes have been fabricated via a simple vacuum-filtration procedure to stack δ-MnO2@carbon nanotubes (CNTs) composite layer and pure CNT layer one by one with CNT layers ended. The lightweight CNTs layers served as both current collector and supporter, while the MnO2@CNTs composite layers with birnessite-type MnO2 worked as active layer and made the main contribution to the capacitance. At a low discharge current of 0.2 A g(-1), the layered films displayed a high areal capacitance of 0.293 F cm(-2) with a mass of 1.97 mg cm(-2) (specific capacitance of 149 F g(-1)) and thickness of only 16.5 μm, and hence an volumetric capacitance of about 177.5 F cm(-3). Moreover, the films also exhibited a good rate capability (only about 15% fading for the capacitance when the discharge current increased to 5 A g(-1) from 0.2 A g(-1)), outstanding cycling stability (about 90% of the initial capacitance was remained after 5,000 cycles) and high flexibility (almost no performance change when bended to different angles). In addition, the capacitance of the films increased proportionally with the stacked layers and the geometry area. E.g., when the stacked layers were three times many with a mass of 6.18 mg cm(-2), the areal capacitance of the films was increased to 0.764 F cm(-2) at 0.5 A g(-1), indicating a high electronic conductivity. It is not overstated to say that the flexible and lightweight layered films emerged high potential for future practical applications as supercapacitor electrodes.

Biowaste-Derived Hierarchical Porous Carbon Nanosheets for Ultrahigh Power Density Supercapacitors.

PubMed

Yu, Dengfeng; Chen, Chong; Zhao, Gongyuan; Sun, Lei; Du, Baosheng; Zhang, Hong; Li, Zhuo; Sun, Ye; Besenbacher, Flemming; Yu, Miao

2018-03-05

Low-cost activated carbons with high capacitive properties remain desirable for supercapacitor applications. Herein, a three-dimensional scaffolding framework of porous carbon nanosheets (PCNSs) has been produced from a typical biowaste, namely, ground cherry calyces, the specific composition and natural structures of which have contributed to the PCNSs having a very large specific surface area of 1612 m 2  g -1 , a hierarchical pore size distribution, a turbostratic carbon structure with a high degree graphitization, and about 10 % oxygen and nitrogen heteroatoms. A high specific capacitance of 350 F g -1 at 0.1 A g -1 has been achieved in a two-electrode system with 6 m KOH; this value is among the highest specific capacitance of biomass-derived carbon materials. More inspiringly, a high energy density of 22.8 Wh kg -1 at a power density of 198.8 W kg -1 can be obtained with 1 m aqueous solution of Li 2 SO 4 , and an ultrahigh energy density of 81.4 Wh kg -1 at a power density of 446.3 W kg -1 is realized with 1-ethyl-3-methylimidazolium tetrafluoroborate electrolyte. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Response to capacitating stimuli indicates extender-related differences in boar sperm function.

PubMed

Schmid, S; Henning, H; Petrunkina, A M; Weitze, K F; Waberski, D

2013-10-01

Spermatozoa, especially those of the porcine species, are highly susceptible to in vitro chilling and ageing. Extenders are continuously developed to protect boar spermatozoa from chilling injury. New semen extenders and other modified preservation strategies require sensitive testing for essential sperm functions. The key process on the pathway of fertilization is capacitation. The aim of the present study was to examine whether the specific response to capacitating stimuli is sensitive enough to indicate different preservation capacities of extenders during hypothermic storage of boar spermatozoa. Semen was diluted in Beltsville Thawing Solution (BTS) and Androstar Plus and kept for 3 h at 22°C or stored at 17°C, 10°C, and 5°C. Semen was analyzed at 24 and 96 h of storage. Motility and membrane integrity remained at high levels, except for lower values when stored in BTS at 5°C. Washed subsamples were incubated in capacitating medium (Tyrode) and control medium and were assessed for intracellular calcium concentration and integrity of plasma membranes using a flow cytometer. On the basis of the loss of low-calcium live cells in a kinetic approach, the specific response to capacitation stimuli was determined. There was a higher loss of response in semen stored hypothermically in the standard extender BTS compared to Androstar Plus. Assessment of the extent of phospholipid disorder under capacitating and control conditions by use of merocyanine staining did not reveal any significant extender-related differences. A field insemination trial with 778 sows was performed to relate in vitro results to fertility. Fertility parameters did not differ in semen stored up to 48 h at 10°C in Androstar Plus compared to controls stored at 17°C in BTS. In conclusion, assessment of specific reactivity to capacitating stimuli appears to be a sensitive tool for detection of extender-dependent alterations in functionality of chilled boar spermatozoa.

Activated carbon derived from harmful aquatic plant for high stable supercapacitors

NASA Astrophysics Data System (ADS)

Li, Jiangfeng; Wu, Qingsheng

2018-01-01

Considering cost and environmental protection, the harmful aquatic plant altemanthera philoxeroides derived carbon material with super high specific surface area (2895 m2 g-1) is an ideal electrode material for supercapacitor. The structure and composition of these carbon materials were characterized by SEM, EDS, XPS and BET measurements. The obtained material exhibits a maximum specific capacitance of 275 F g-1 at 0.5 A g-1 and retains a capacitance of 210 F g-1 even at 50 A g-1. In addition, it also shows excellent capacity retention of 5000 cycles at 10 A g-1.

Electrostatic Spray Deposition-Based Manganese Oxide Films-From Pseudocapacitive Charge Storage Materials to Three-Dimensional Microelectrode Integrands.

PubMed

Agrawal, Richa; Adelowo, Ebenezer; Baboukani, Amin Rabiei; Villegas, Michael Franc; Henriques, Alexandra; Wang, Chunlei

2017-07-26

In this study, porous manganese oxide (MnO x ) thin films were synthesized via electrostatic spray deposition (ESD) and evaluated as pseudocapacitive electrode materials in neutral aqueous media. Very interestingly, the gravimetric specific capacitance of the ESD-based electrodes underwent a marked enhancement upon electrochemical cycling, from 72 F∙g -1 to 225 F∙g -1 , with a concomitant improvement in kinetics and conductivity. The change in capacitance and resistivity is attributed to a partial electrochemical phase transformation from the spinel-type hausmannite Mn₃O₄ to the conducting layered birnessite MnO₂. Furthermore, the films were able to retain 88.4% of the maximal capacitance after 1000 cycles. Upon verifying the viability of the manganese oxide films for pseudocapacitive applications, the thin films were integrated onto carbon micro-pillars created via carbon microelectromechanical systems (C-MEMS) for examining their application as potential microelectrode candidates. In a symmetric two-electrode cell setup, the MnO x /C-MEMS microelectrodes were able to deliver specific capacitances as high as 0.055 F∙cm -2 and stack capacitances as high as 7.4 F·cm -3 , with maximal stack energy and power densities of 0.51 mWh·cm -3 and 28.3 mW·cm -3 , respectively. The excellent areal capacitance of the MnO x -MEs is attributed to the pseudocapacitive MnO x as well as the three-dimensional architectural framework provided by the carbon micro-pillars.

Porous Carbon with Willow-Leaf-Shaped Pores for High-Performance Supercapacitors.

PubMed

Shi, Yanhong; Zhang, Linlin; Schon, Tyler B; Li, Huanhuan; Fan, Chaoying; Li, Xiaoying; Wang, Haifeng; Wu, Xinglong; Xie, Haiming; Sun, Haizhu; Seferos, Dwight S; Zhang, Jingping

2017-12-13

A novel kind of biomass-derived, high-oxygen-containing carbon material doped with nitrogen that has willow-leaf-shaped pores was synthesized. The obtained carbon material has an exotic hierarchical pore structure composed of bowl-shaped macropores, willow-leaf-shaped pores, and an abundance of micropores. This unique hierarchical porous structure provides an effective combination of high current densities and high capacitance because of a pseudocapacitive component that is afforded by the introduction of nitrogen and oxygen dopants. Our synthetic optimization allows further improvements in the performance of this hierarchical porous carbon (HPC) material by providing a high degree of control over the graphitization degree, specific surface area, and pore volume. As a result, a large specific surface area (1093 m 2 g -1 ) and pore volume (0.8379 cm 3 g -1 ) are obtained for HPC-650, which affords fast ion transport because of its short ion-diffusion pathways. HPC-650 exhibits a high specific capacitance of 312 F g -1 at 1 A g -1 , retaining 76.5% of its capacitance at 20 A g -1 . Moreover, it delivers an energy density of 50.2 W h kg -1 at a power density of 1.19 kW kg -1 , which is sufficient to power a yellow-light-emitting diode and operate a commercial scientific calculator.

Capacitive behavior of highly-oxidized graphite

NASA Astrophysics Data System (ADS)

Ciszewski, Mateusz; Mianowski, Andrzej

2014-09-01

Capacitive behavior of a highly-oxidized graphite is presented in this paper. The graphite oxide was synthesized using an oxidizing mixture of potassium chlorate and concentrated fuming nitric acid. As-oxidized graphite was quantitatively and qualitatively analyzed with respect to the oxygen content and the species of oxygen-containing groups. Electrochemical measurements were performed in a two-electrode symmetric cell using KOH electrolyte. It was shown that prolonged oxidation causes an increase in the oxygen content while the interlayer distance remains constant. Specific capacitance increased with oxygen content in the electrode as a result of pseudo-capacitive effects, from 0.47 to 0.54 F/g for a scan rate of 20 mV/s and 0.67 to 1.15 F/g for a scan rate of 5 mV/s. Better cyclability was observed for the electrode with a higher oxygen amount.

Stretchable V2O5/PEDOT supercapacitors: a modular fabrication process and charging with triboelectric nanogenerators.

PubMed

Qi, Ruijie; Nie, Jinhui; Liu, Mingyang; Xia, Mengyang; Lu, Xianmao

2018-04-26

Stretchable energy storage devices are of great importance for the viable applications of wearable/stretchable electronics. Studies on stretchable energy storage devices, especially supercapacitors (SCs), have shown encouraging progress. However, challenges still remain in the pursuit of high specific capacitances and facile fabrication methods. Herein, we report a modular materials fabrication and assembly process for stretchable SCs. With a V2O5/PEDOT composite as the active material, the resulting stretchable SCs exhibited high areal specific capacitances up to 240 mF cm-2 and good capacitance retention at a strain of 50%. To demonstrate the facile assembly process, a stretchable wristband was fabricated by simply assembling SC cells in series to deliver a voltage higher than 2 V. Charging the wristband with a triboelectric nanogenerator (TENG) to light an LED was further demonstrated, indicating the potential to integrate our SCs with environmental energy harvesters for self-powered stretchable devices.

Interconnected V2O5 nanoporous network for high-performance supercapacitors.

PubMed

Saravanakumar, B; Purushothaman, Kamatchi K; Muralidharan, G

2012-09-26

Vanadium pentoxide (V(2)O(5)) has attracted attention for supercapcitor applications because of its extensive multifunctional properties. In the present study, V(2)O(5) nanoporous network was synthesized via simple capping-agent-assisted precipitation technique and it is further annealed at different temperatures. The effect of annealing temperature on the morphology, electrochemical and structural properties, and stability upon oxidation-reduction cycling has been analyzed for supercapacitor application. We achieved highest specific capacitance of 316 F g(-1) for interconnected V(2)O(5) nanoporous network. This interconnected nanoporous network creates facile nanochannels for ion diffusion and facilitates the easy accessibility of ions. Moreover, after six hundred consecutive cycling processes the specific capacitance has changed only by 24%. A simple cost-effective preparation technique of V(2)O(5) nanoporous network with excellent capacitive behavior, energy density, and stability encourages its possible commercial exploitation for the development of high-performance supercapacitors.

Controllable synthesis of layered Co-Ni hydroxide hierarchical structures for high-performance hybrid supercapacitors

NASA Astrophysics Data System (ADS)

Yuan, Peng; Zhang, Ning; Zhang, Dan; Liu, Tao; Chen, Limiao; Ma, Renzhi; Qiu, Guanzhou; Liu, Xiaohe

2016-01-01

A facile solvothermal method is developed for synthesizing layered Co-Ni hydroxide hierarchical structures by using hexamethylenetetramine (HMT) as alkaline reagent. The electrochemical measurements reveal that the specific capacitances of layered bimetallic (Co-Ni) hydroxides are generally superior to those of layered monometallic (Co, Ni) hydroxides. The as-prepared Co0.5Ni0.5 hydroxide hierarchical structures possesses the highest specific capacitance of 1767 F g-1 at a galvanic current density of 1 A g-1 and an outstanding specific capacitance retention of 87% after 1000 cycles. In comparison with the dispersed nanosheets of Co-Ni hydroxide, layered hydroxide hierarchical structures show much superior electrochemical performance. This study provides a promising method to construct hierarchical structures with controllable transition-metal compositions for enhancing the electrochemical performance in hybrid supercapacitors.

Redox-active triazatruxene-based conjugated microporous polymers for high-performance supercapacitors† †Electronic supplementary information (ESI) available: Synthetic procedures and characterization data for all new compounds; general experimental method; thermogravimetry curves; PXRD patterns; SEM and TEM images; XPS spectra. See DOI: 10.1039/c6sc05532j Click here for additional data file.

PubMed Central

Li, Xiang-Chun; Zhang, Yizhou; Wang, Chun-Yu; Wan, Yi

2017-01-01

Conjugated polymers (CPs) have been intensively explored for various optoelectronic applications in the last few decades. Nevertheless, CP based electrochemical energy storage devices such as supercapacitors remain largely unexplored. This is mainly owing to the low specific capacitance, poor structural/electrochemical stability, and low energy density of most existing CPs. In this contribution, a novel set of redox-active conjugated microporous polymers, TAT-CMP-1 and TAT-CMP-2, based on nitrogen-rich and highly conductive triazatruxene building blocks, were successfully designed and synthesized to explore their potential application as efficient and stable electrode materials for supercapacitors. Despite a moderate surface area of 88 m2 g–1 for TAT-CMP-1 and 106 m2 g–1 for TAT-CMP-2, exceptional specific capacitances of 141 F g–1 and 183 F g–1 were achieved at a current density of 1 A g–1. The resulting polymers exhibited unusually high areal specific capacitance (>160 μF cm–2), which is attributed to the pseudocapacitance resulting from redox-active structures with high nitrogen content. More importantly, the TAT-CMP-2 electrode exhibits excellent cycling stability: only 5% capacitance fading is observed after 10 000 cycles at a high current density of 10 A g–1, enabling the possible use of these materials as electrodes in electrochemical devices. PMID:28451362

CoNi2 S4 Nanoparticle/Carbon Nanotube Sponge Cathode with Ultrahigh Capacitance for Highly Compressible Asymmetric Supercapacitor.

PubMed

Cao, Xin; He, Jin; Li, Huan; Kang, Liping; He, Xuexia; Sun, Jie; Jiang, Ruibing; Xu, Hua; Lei, Zhibin; Liu, Zong-Huai

2018-05-30

Compared with other flexible energy-storage devices, the design and construction of the compressible energy-storage devices face more difficulty because they must accommodate large strain and shape deformations. In the present work, CoNi 2 S 4 nanoparticles/3D porous carbon nanotube (CNT) sponge cathode with highly compressible property and excellent capacitance is prepared by electrodepositing CoNi 2 S 4 on CNT sponge, in which CoNi 2 S 4 nanoparticles with size among 10-15 nm are uniformly anchored on CNT, causing the cathode to show a high compression property and gives high specific capacitance of 1530 F g -1 . Meanwhile, Fe 2 O 3 /CNT sponge anode with specific capacitance of 460 F g -1 in a prolonged voltage window is also prepared by electrodepositing Fe 2 O 3 nanosheets on CNT sponge. An asymmetric supercapacitor (CoNi 2 S 4 /CNT//Fe 2 O 3 /CNT) is assembled by using CoNi 2 S 4 /CNT sponge as positive electrode and Fe 2 O 3 /CNT sponge as negative electrode in 2 m KOH solution. It exhibits excellent energy density of up to 50 Wh kg -1 at a power density of 847 W kg -1 and excellent cycling stability at high compression. Even at a strain of 85%, about 75% of the initial capacitance is retained after 10 000 consecutive cycles. The CoNi 2 S 4 /CNT//Fe 2 O 3 /CNT device is a promising candidate for flexible energy devices due to its excellent compressibility and high energy density. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

All-solid-state asymmetric supercapacitors based on Fe-doped mesoporous Co3O4 and three-dimensional reduced graphene oxide electrodes with high energy and power densities.

PubMed

Zhang, Cheng; Wei, Jun; Chen, Leiyi; Tang, Shaolong; Deng, Mingsen; Du, Youwei

2017-10-19

An asymmetric supercapacitor offers opportunities to effectively utilize the full potential of the different potential windows of the two electrodes for a higher operating voltage, resulting in an enhanced specific capacitance and significantly improved energy without sacrificing the power delivery and cycle life. To achieve high energy and power densities, we have synthesized an all-solid-state asymmetric supercapacitor with a wider voltage range using Fe-doped Co 3 O 4 and three-dimensional reduced graphene oxide (3DrGO) as the positive and negative electrodes, respectively. In contrast to undoped Co 3 O 4 , the increased density of states and modified charge spatial separation endow the Fe-doped Co 3 O 4 electrode with greatly improved electrochemical capacitive performance, including high specific capacitance (1997 F g -1 and 1757 F g -1 at current densities of 1 and 20 A g -1 , respectively), excellent rate capability, and superior cycling stability. Remarkably, the optimized all-solid-state asymmetric supercapacitor can be cycled reversibly in a wide range of 0-1.8 V, thus delivering a high energy density (270.3 W h kg -1 ), high power density (9.0 kW kg -1 at 224.2 W h kg -1 ), and excellent cycling stability (91.8% capacitance retention after 10 000 charge-discharge cycles at a constant current density of 10 A g -1 ). The superior capacitive performance suggests that such an all-solid-state asymmetric supercapacitor shows great potential for developing energy storage systems with high levels of energy and power delivery.

Three-Dimensional Hierarchical NixCo1-xO/NiyCo2-yP@C Hybrids on Nickel Foam for Excellent Supercapacitors.

PubMed

Shao, Yubo; Zhao, Yongqing; Li, Hua; Xu, Cailing

2016-12-28

Active materials and special structures of the electrode have decisive influence on the electrochemical properties of supercapacitors. Herein, three-dimensional (3D) hierarchical Ni x Co 1-x O/Ni y Co 2-y P@C (denoted as NiCoOP@C) hybrids have been successfully prepared by a phosphorization treatment of hierarchical Ni x Co 1-x O@C grown on nickel foam. The resulting NiCoOP@C hybrids exhibit an outstanding specific capacitance and cycle performance because they couple the merits of the superior cycling stability of Ni x Co 1-x O, the high specific capacitance of Ni y Co 2-y P, the mechanical stability of carbon layer, and the 3D hierarchical structure. The specific capacitance of 2638 F g -1 can be obtained at the current density of 1 A g -1 , and even at the current density of 20 A g -1 , the NiCoOP@C electrode still possesses a specific capacitance of 1144 F g -1 . After 3000 cycles at 10 A g -1 , 84% of the initial specific capacitance is still remained. In addition, an asymmetric ultracapacitor (ASC) is assembled through using NiCoOP@C hybrids as anode and activated carbon as cathode. The as-prepared ASC obtains a maximum energy density of 39.4 Wh kg -1 at a power density of 394 W kg -1 and still holds 21 Wh kg -1 at 7500 W kg -1 .

Flexible Fe3O4@Carbon Nanofibers Hierarchically Assembled with MnO2 Particles for High-Performance Supercapacitor Electrodes.

PubMed

Iqbal, Nousheen; Wang, Xianfeng; Babar, Aijaz Ahmed; Zainab, Ghazala; Yu, Jianyong; Ding, Bin

2017-11-09

Increasing use of wearable electronic devices have resulted in enhanced demand for highly flexible supercapacitor electrodes with superior electrochemical performance. In this study, flexible composite membranes with electrosprayed MnO 2 particles uniformly anchored on Fe 3 O 4 doped electrospun carbon nanofibers (Fe 3 O 4 @CNF Mn ) have been prepared as flexible electrodes for high-performance supercapacitors. The interconnected porous beaded structure ensures free movement of electrolyte within the composite membranes, therefore, the developed supercapacitor electrodes not only offer high specific capacitance of ~306 F/g, but also exhibit good capacitance retention of ~85% after 2000 cycles, which certify that the synthesized electrodes offer high and stable electrochemical performance. Additionally, the supercapacitors fabricated from our developed electrodes well maintain their performance under flexural stress and exhibit a very minute change in specific capacitance even up to 180° bending angle. The developed electrode fabrication strategy integrating electrospinning and electrospray techniques paves new insights into the development of potential functional nanofibrous materials for light weight and flexible wearable supercapacitors.

Solution growth of NiO nanosheets supported on Ni foam as high-performance electrodes for supercapacitors

PubMed Central

2014-01-01

Well-aligned nickel oxide (NiO) nanosheets with the thickness of a few nanometers supported on a flexible substrate (Ni foam) have been fabricated by a hydrothermal approach together with a post-annealing treatment. The three-dimensional NiO nanosheets were further used as electrode materials to fabricate supercapacitors, with high specific capacitance of 943.5, 791.2, 613.5, 480, and 457.5 F g-1 at current densities of 5, 10, 15, 20, and 25 A g-1, respectively. The NiO nanosheets combined well with the substrate. When the electrode material was bended, it can still retain 91.1% of the initial capacitance after 1,200 charging/discharging cycles. Compared with Co3O4 and NiO nanostructures, the specific capacitance of NiO nanosheets is much better. These characteristics suggest that NiO nanosheet electrodes are promising for energy storage application with high power demands. PMID:25276099

Ternary manganese ferrite/graphene/polyaniline nanostructure with enhanced electrochemical capacitance performance

NASA Astrophysics Data System (ADS)

Xiong, Pan; Hu, Chenyao; Fan, Ye; Zhang, Wenyao; Zhu, Junwu; Wang, Xin

2014-11-01

A ternary manganese ferrite/graphene/polyaniline (MGP) nanostructure is designed and synthesized via a facile two-step approach. This nanostructure exhibits outstanding electrochemical performances, such as high specific capacitance (454.8 F g-1 at 0.2 A g-1), excellent rate capability (75.8% capacity retention at 5 A g-1), and good cycling stability (76.4% capacity retention after 5000 cycles at 2 A g-1), which are superior to those of its individual components (manganese ferrite, reduced-graphene oxide, polyaniline) and corresponding binary hybrids (manganese ferrite/graphene (MG), manganese ferrite/polyaniline (MP), and graphene/polyaniline (GP)). A symmetric supercapacitor device using the as-obtained hybrid has been fabricated and tested. The device exhibits a high specific capacitance of 307.2 F g-1 at 0.1 A g-1 with a maximum energy density of 13.5 W h kg-1. The high electrochemical performance of ternary MGP can be attributed to its well-designed nanostructure and the synergistic effect of the individual components.

Hierarchical network architectures of carbon fiber paper supported cobalt oxide nanonet for high-capacity pseudocapacitors.

PubMed

Yang, Lei; Cheng, Shuang; Ding, Yong; Zhu, Xingbao; Wang, Zhong Lin; Liu, Meilin

2012-01-11

We present a high-capacity pseudocapacitor based on a hierarchical network architecture consisting of Co(3)O(4) nanowire network (nanonet) coated on a carbon fiber paper. With this tailored architecture, the electrode shows ideal capacitive behavior (rectangular shape of cyclic voltammograms) and large specific capacitance (1124 F/g) at high charge/discharge rate (25.34 A/g), still retaining ~94% of the capacitance at a much lower rate of 0.25 A/g. The much-improved capacity, rate capability, and cycling stability may be attributed to the unique hierarchical network structures, which improves electron/ion transport, enhances the kinetics of redox reactions, and facilitates facile stress relaxation during cycling. © 2011 American Chemical Society

Facilitated charge transport in ternary interconnected electrodes for flexible supercapacitors with excellent power characteristics

NASA Astrophysics Data System (ADS)

Chen, Wanjun; He, Yongmin; Li, Xiaodong; Zhou, Jinyuan; Zhang, Zhenxing; Zhao, Changhui; Gong, Chengshi; Li, Shuankui; Pan, Xiaojun; Xie, Erqing

2013-11-01

Flexible and high performance supercapacitors are very critical in modern society. In order to develop the flexible supercapacitors with high power density, free-standing and flexible three-dimensional graphene/carbon nanotubes/MnO2 (3DG/CNTs/MnO2) composite electrodes with interconnected ternary 3D structures were fabricated, and the fast electron and ion transport channels were effectively constructed in the rationally designed electrodes. Consequently, the obtained 3DG/CNTs/MnO2 composite electrodes exhibit superior specific capacitance and rate capability compared to 3DG/MnO2 electrodes. Furthermore, the 3DG/CNTs/MnO2 based asymmetric supercapacitor demonstrates the maximum energy and power densities of 33.71 W h kg-1 and up to 22 727.3 W kg-1, respectively. Moreover, the asymmetric supercapacitor exhibits excellent cycling stability with 95.3% of the specific capacitance maintained after 1000 cycle tests. Our proposed synthesis strategy to construct the novel ternary 3D structured electrodes can be efficiently applied to other high performance energy storage/conversion systems.Flexible and high performance supercapacitors are very critical in modern society. In order to develop the flexible supercapacitors with high power density, free-standing and flexible three-dimensional graphene/carbon nanotubes/MnO2 (3DG/CNTs/MnO2) composite electrodes with interconnected ternary 3D structures were fabricated, and the fast electron and ion transport channels were effectively constructed in the rationally designed electrodes. Consequently, the obtained 3DG/CNTs/MnO2 composite electrodes exhibit superior specific capacitance and rate capability compared to 3DG/MnO2 electrodes. Furthermore, the 3DG/CNTs/MnO2 based asymmetric supercapacitor demonstrates the maximum energy and power densities of 33.71 W h kg-1 and up to 22 727.3 W kg-1, respectively. Moreover, the asymmetric supercapacitor exhibits excellent cycling stability with 95.3% of the specific capacitance maintained after 1000 cycle tests. Our proposed synthesis strategy to construct the novel ternary 3D structured electrodes can be efficiently applied to other high performance energy storage/conversion systems. Electronic supplementary information (ESI) available: Additional experimental details; calculations of the specific capacitances, and energy and power densities; additional SEM and optical images; XPS results; additional electrochemical results. See DOI: 10.1039/c3nr03923d

Fabrication of 3-D nanodimensioned electric double layer capacitor structures using block copolymer templates.

PubMed

Rasappa, Sozaraj; Borah, Dipu; Senthamaraikannan, Ramsankar; Faulkner, Colm C; Holmes, Justin D; Morris, Michael A

2014-07-01

The need for materials for high energy storage has led to very significant research in supercapacitor systems. These can exhibit electrical double layer phenomena and capacitances up to hundreds of F/g. Here, we demonstrate a new supercapacitor fabrication methodology based around the microphase separation of PS-b-PMMA which has been used to prepare copper nanoelectrodes of dimension -13 nm. These structures provide excellent capacitive performance with a maximum specific capacitance of -836 F/g for a current density of 8.06 A/g at a discharge current as high as 75 mA. The excellent performance is due to a high surface area: volume ratio. We suggest that this highly novel, easily fabricated structure might have a number of important applications.

Hierarchically structured Ni(3)S(2)/carbon nanotube composites as high performance cathode materials for asymmetric supercapacitors.

PubMed

Dai, Chao-Shuan; Chien, Pei-Yi; Lin, Jeng-Yu; Chou, Shu-Wei; Wu, Wen-Kai; Li, Ping-Hsuan; Wu, Kuan-Yi; Lin, Tsung-Wu

2013-11-27

The Ni3S2 nanoparticles with the diameters ranging from 10 to 80 nm are grown on the backbone of conductive multiwalled carbon nanotubes (MWCNTs) using a glucose-assisted hydrothermal method. It is found that the Ni3S2 nanoparticles deposited on MWCNTs disassemble into smaller components after the composite electrode is activated by the consecutive cyclic voltammetry scan in a 2 M KOH solution. Therefore, the active surface area of the Ni3S2 nanoparticles is increased, which further enhances the capacitive performance of the composite electrode. Because the synergistic effect of the Ni3S2 nanoparticles and MWCNTs on the capacitive performance of the composite electrode is pronounced, the composite electrode shows a high specific capacitance of 800 F/g and great cycling stability at a current density of 3.2 A/g. To examine the capacitive performance of the composite electrode in a full-cell configuration, an asymmetric supercapacitor device was fabricated by using the composite of Ni3S2 and MWCNTs as the cathode and activated carbon as the anode. The fabricated device can be operated reversibly between 0 and 1.6 V, and obtain a high specific capacitance of 55.8 F/g at 1 A/g, which delivers a maximum energy density of 19.8 Wh/kg at a power density of 798 W/kg. Furthermore, the asymmetric supercapacitor shows great stability based on the fact that the device retains 90% of its initial capacitance after a consecutive 5000 cycles of galvanostatic charge-discharge performed at a current density of 4 A/g.

Fabrication of hierarchical porous nickel based metal-organic framework (Ni-MOF) constructed with nanosheets as novel pseudo-capacitive material for asymmetric supercapacitor.

PubMed

Du, Pengcheng; Dong, Yuman; Liu, Chang; Wei, Wenli; Liu, Dong; Liu, Peng

2018-05-15

Hierarchical porous nickel based metal-organic framework (Ni-MOF) constructed with nanosheets is fabricated by a facile hydrothermal process with the existence of trimesic acid and nickel ions. Various structures of Ni-MOFs can be obtained through adjusting the molar ratio of trimesic acid and nickel ion, the obtained hierarchical porous Ni-MOF exhibits optimal porous structure, which also possesses largest specific surface area. The hierarchical porous structure constructed with nanosheets can supply more active sites for electrochemical reactions to realize the excellent electrochemical properties, thus the hierarchical porous Ni-MOF reveals an outstanding specific capacitance of 1057 F/g at current density of 1 A/g, and delivers high specific capacitance of 649 F/g at current density of 30 A/g, indicating that it exhibits good rate capability of 63.4% even up to 30 A/g. The hierarchical porous Ni-MOF keeps 70% of its original value up to 2 500 charge-discharge cycles at the current density of 10 A/g. Furthermore, asymmetric supercapacitors (ASCs) were assembled based on hierarchical porous Ni-MOF and activated carbon (AC), the ASCs reveal specific capacitance of 87 F/g at current density of 0.5 A/g, and exhibit high energy density of 21.05 Wh/kg and power density of 6.03 kW/kg. Additionally, the tandem ASCs can light up a red LED. The hierarchical porous Ni-MOF exhibits promising applications in high performance supercapacitors. Copyright © 2018 Elsevier Inc. All rights reserved.

Helically coiled carbon nanotube forests for use as electrodes in supercapacitors

NASA Astrophysics Data System (ADS)

Childress, Anthony; Ferri, Kevin; Podila, Ramakrishna; Rao, Apparao

Supercapacitors are a class of devices which combine the high energy density of batteries with the power delivery of capacitors, and have benefitted greatly from the incorporation of carbon nanomaterials. In an effort to improve the specific capacitance of these devices, we have produced binder-free electrodes composed of helically coiled carbon nanotube forests grown on stainless steel current collectors with a performance superior to traditional carbon nanomaterials. By virtue of their helicity, the coiled nanotubes provide a greater surface area for energy storage than their straight counterparts, thus improving the specific capacitance. Furthermore, we used an Ar plasma treatment to increase the electronic density of states, and thereby the quantum capacitance, through the introduction of defects.

MnO2 Nanorods Intercalating Graphene Oxide/Polyaniline Ternary Composites for Robust High-Performance Supercapacitors

NASA Astrophysics Data System (ADS)

Han, Guangqiang; Liu, Yun; Zhang, Lingling; Kan, Erjun; Zhang, Shaopeng; Tang, Jian; Tang, Weihua

2014-04-01

New ternary composites of MnO2 nanorods, polyaniline (PANI) and graphene oxide (GO) have been prepared by a two-step process. The 100 nm-long MnO2 nanorods with a diameter ~20 nm are conformably coated with PANI layers and fastened between GO layers. The MnO2 nanorods incorporated ternary composites electrode exhibits significantly increased specific capacitance than PANI/GO binary composite in supercapacitors. The ternary composite with 70% MnO2 exhibits a highest specific capacitance reaching 512 F/g and outstanding cycling performance, with ~97% capacitance retained over 5000 cycles. The ternary composite approach offers an effective solution to enhance the device performance of metal-oxide based supercapacitors for long cycling applications.

Effects of Carbonization Temperature on Nature of Nanostructured Electrode Materials Derived from Fe-MOF for Supercapacitors

NASA Astrophysics Data System (ADS)

Sui, Yanwei; Zhang, Dongling; Han, Yongpeng; Sun, Zhi; Qi, Jiqiu; Wei, Fuxiang; He, Yezeng; Meng, Qingkun

2018-05-01

This work successfully demonstrates various temperature carbonization of iron based metal organic framework to derive electrode materials for supercapacitors. Furthermore, impacts of calcined temperatures on the nature of as-prepared products are reported, and samples obtained at 300, 400, 500, 600 and 700 °C were investigated respectively. The products reveals excellent electrochemical performance. Carbonized at 600 °C, the composite materials display the highest specific capacitance of 972 F/g at a current density of 1 A/g. Carbonized at 500 °C, the capacitance retention of materials reach up to 93%. The high specific capacitance and excellent cyclic stability of the developed materials would exhibit nice prospect for the practical utilization of electrode materials.

Fabrication of flower-like Ni{sub 3}(NO{sub 3}){sub 2}(OH){sub 4} and their electrochemical properties evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kong, Ling-Bin, E-mail: konglb@lut.cn; School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050; Deng, Li

Graphical abstract: Ni{sub 3}(NO{sub 3}){sub 2}(OH){sub 4} nano-flakes materials, which have a flower-like structure, were successfully synthesized by a facile solvothermal method without adding any surfactant. The as-prepared Ni{sub 3}(NO{sub 3}){sub 2}(OH){sub 4} possesses a maximum specific capacitance of 2212.5 F g{sup −1} at the current density of 5 mA, suggesting its potential application in electrode material for secondary batteries and electrochemical capacitors. Highlights: ► Flower-like Ni{sub 3}(NO{sub 3}){sub 2}(OH){sub 4} materials were fabricated in a simple method. ► High specific capacitance of 2212.5 F g{sup −1} has been achieved. ► For the first time the effects of concentration andmore » temperature on its specific capacitance has been studied. -- Abstract: Flower-like Ni{sub 3}(NO{sub 3}){sub 2}(OH){sub 4} was successfully synthesized by a facile solvothermal method. The microstructure and surface morphology of prepared Ni{sub 3}(NO{sub 3}){sub 2}(OH){sub 4} were physically characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and transmission electron microscope (TEM). The electrochemical properties studies were carried out using cyclic voltammetry (CV), chronopotentiometry technology and AC impedance spectroscopy, respectively. The results indicate that the flower-like structure has a profound impact on electrode performance at high discharge capacitance. A maximum specific capacitance of 2212.5 F g{sup −1} at the current density of 5 mA could be achieved, suggesting its potential application in electrode material for secondary batteries and electrochemical capacitors. Furthermore, the effects of Ni(NO{sub 3}){sub 2}·6H{sub 2}O concentration and temperature on the microstructure and specific capacitance of prepared Ni{sub 3}(NO{sub 3}){sub 2}(OH){sub 4} have also been systematically studied. The results show that flower-like structure can be formed when the concentration is appropriate, while the temperature has just little effect on its electrochemical properties.« less

Three-dimensional structures of graphene/polyaniline hybrid films constructed by steamed water for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Zhang, Liling; Huang, Da; Hu, Nantao; Yang, Chao; Li, Ming; Wei, Hao; Yang, Zhi; Su, Yanjie; Zhang, Yafei

2017-02-01

A novel three-dimensional (3D) structure of reduced graphene oxide/polyaniline (rGO/PANI) hybrid films has been demonstrated for high-performance supercapacitors. Steamed water in closed vessels with high pressure and moderately high temperature is applied to facilely construct this structure. The as-designed rGO/PANI hybrid films exhibit a highest gravimetric specific capacitance of 1182 F g-1 at 1 A g-1 in the three-electrode test. The assembled symmetric device based on this structure shows both a high capacitance of 808 F g-1 at 1 A g-1 and a high gravimetric energy density (28.06 Wh kg-1 at a power density of 0.25 kW kg-1). Above all, this novel 3D structure constructed by steamed water regulation techniques shows excellent capacitance performance and holds a great promise for high-performance energy storage applications.

Freestanding hierarchically porous carbon framework decorated by polyaniline as binder-free electrodes for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Miao, Fujun; Shao, Changlu; Li, Xinghua; Wang, Kexin; Lu, Na; Liu, Yichun

2016-10-01

Freestanding hierarchically porous carbon electrode materials with favorable features of large surface areas, hierarchical porosity and continuous conducting pathways are very attractive for practical applications in electrochemical devices. Herein, three-dimensional freestanding hierarchically porous carbon (HPC) materials have been fabricated successfully mainly by the facile phase separation method. In order to further improve the energy storage ability, polyaniline (PANI) with high pseudocapacitance has been decorated on HPC through in situ chemical polymerization of aniline monomers. Benefiting from the synergistic effects between HPC and PANI, the resulting HPC/PANI composites as electrode materials present dramatic electrochemical performance with high specific capacitance up to 290 F g-1 at 0.5 A g-1 and good rate capability with ∼86% (248 F g-1) capacitance retention at 64 A g-1 of initial capacitance in three-electrode configuration. Moreover, the as-assembled symmetric supercapacitor based on HPC/PANI composites also demonstrates good capacitive properties with high energy density of 9.6 Wh kg-1 at 223 W kg-1 and long-term cycling stability with 78% capacitance retention after 10 000 cycles. Therefore, this work provides a new approach for designing high-performance electrodes with exceptional electrochemical performance, which are very promising for practical application in the energy storage field.

Porous ZnO-Coated Co3O4 Nanorod as a High-Energy-Density Supercapacitor Material.

PubMed

Gao, Miao; Wang, Wei-Kang; Rong, Qing; Jiang, Jun; Zhang, Ying-Jie; Yu, Han-Qing

2018-06-27

Co 3 O 4 with a high theoretical capacitance has been widely recognized as a promising electrode material for supercapacitor, but its poor electrical conductivity and stability limit its practical applications. Here, we developed an effective synthetic route to synthesize one-dimensional (1D) porous ZnO/Co 3 O 4 heterojunction composites. Benefiting from the heterostructure to promote the charge transfer and protect Co 3 O 4 from corrosion and the 1D porous structure to improve ion diffusion and prevent structural collapse in charge and discharge process, the as-prepared ZnO/Co 3 O 4 composites exhibited an excellent capacitive performance and good cycling stability. The specific capacitance of the ZnO/Co 3 O 4 -450 (1135 F g -1 at 1 A g -1 ) was 1.4 times higher than that of Co 3 O 4 (814 F g -1 ), and the high-rate performance for ZnO/Co 3 O 4 -450 was 4.9 times better than that of Co 3 O 4 . Also, approximately 83% of its specific capacitance was retained after 5000 cycles at 10 A g -1 . Most importantly, the as-fabricated asymmetric supercapacitor, with a ZnO/Co 3 O 4 -450 positive electrode and an activated carbon negative electrode, delivered a prominent energy density of 47.7 W h kg -1 and a high power density of 7500 W kg -1 . Thus, the ZnO/Co 3 O 4 composites could serve as a high-activity material for supercapacitor and the preparation method also offers an attractive strategy to enhance the capacitive performance of Co 3 O 4 .

Densely-packed graphene/conducting polymer nanoparticle papers for high-volumetric-performance flexible all-solid-state supercapacitors

NASA Astrophysics Data System (ADS)

Yang, Chao; Zhang, Liling; Hu, Nantao; Yang, Zhi; Wei, Hao; Xu, Zhichuan J.; Wang, Yanyan; Zhang, Yafei

2016-08-01

Graphene-based all-solid-state supercapacitors (ASSSCs) are one of the most ideal candidates for high-performance flexible power sources. The achievement of high volumetric energy density is highly desired for practical application of this type of ASSSCs. Here, we present a facile method to boost volumetric performances of graphene-based flexible ASSSCs through incorporation of ultrafine polyaniline-poly(4-styrenesulfonate) (PANI-PSS) nanoparticles in reduced graphene oxide (rGO) papers. A compact structure is obtained via intimate contact and π-π interaction between PANI-PSS nanoparticles and rGO sheets. The hybrid paper electrode with the film thickness of 13.5 μm, shows an extremely high volumetric specific capacitance of 272 F/cm3 (0.37 A/cm3 in a three-electrode cell). The assembled ASSSCs show a large volumetric specific capacitance of 217 F/cm3 (0.37 A/cm3 in a two-electrode cell), high volumetric energy and power density, excellent capacitance stability, small leakage current as well as low self-discharge characteristics, revealing the usefulness of this robust hybrid paper for high-performance flexible energy storage devices.

Ultra-facile fabrication of phosphorus doped egg-like hierarchic porous carbon with superior supercapacitance performance by microwave irradiation combining with self-activation strategy

NASA Astrophysics Data System (ADS)

Zhang, Deyi; Han, Mei; Li, Yubing; He, Jingjing; Wang, Bing; Wang, Kunjie; Feng, Huixia

2017-12-01

Herein, we report an ultra-facile fabrication method for a phosphorus doped egg-like hierarchic porous carbon by microwave irradiation combining with self-activation strategy under air atmosphere. Comparing with the traditional pyrolytic carbonization method, the reported method exhibits incomparable merits, such as high energy efficiency, ultra-fast and inert atmosphere protection absent fabrication process. Similar morphology and graphitization degree with the sample fabricated by the traditional pyrolytic carbonization method under inert atmosphere protection for 2 h can be easily achieved by the reported microwave irradiation method just for 3 min under ambient atmosphere. The samples fabricated by the reported method display a unique phosphorus doped egg-like hierarchic porous structure, high specific surface area (1642 m2 g-1) and large pore volume (2.04 cm3 g-1). Specific capacitance of the samples fabricated by the reported method reaches up to 209 F g-1, and over 96.2% of initial capacitance remains as current density increasing from 0.5 to 20 A g-1, indicating the superior capacitance performance of the fabricated samples. The hierarchic porous structure, opened microporosity, additional pseudocapacitance, high electrolyte-accessible surface area and good conductivity make essential contribution to its superior capacitance performance.

Development of Electrochemical Supercapacitors for EMA Applications

NASA Technical Reports Server (NTRS)

Kosek, John A.; Dunning, Thomas; LaConti, Anthony B.

1996-01-01

A limitation of the typical electrochemical capacitor is the maximum available power and energy density, and an improvement in capacitance per unit weight and volume is needed. A solid-ionomer electrochemical capacitor having a unit cell capacitance greater than 2 F/sq cm and a repeating element thickness of 6 mils has been developed. This capacitor could provide high-current pulses for electromechanical actuation (EMA). Primary project objectives were to develop high-capacitance particulates, to increase capacitor gravimetric and volumetric energy densities above baseline and to fabricate a 10-V capacitor with a repeating element thickness of 6 mils or less. Specific EMA applications were identified and capacitor weight and volume projections made.

"Egg-Box"-Assisted Fabrication of Porous Carbon with Small Mesopores for High-Rate Electric Double Layer Capacitors.

PubMed

Kang, Danmiao; Liu, Qinglei; Gu, Jiajun; Su, Yishi; Zhang, Wang; Zhang, Di

2015-11-24

Here we report a method to fabricate porous carbon with small mesopores around 2-4 nm by simple activation of charcoals derived from carbonization of seaweed consisting of microcrystalline domains formed by the "egg-box" model. The existence of mesopores in charcoals leads to a high specific surface area up to 3270 m(2) g(-1), with 95% surface area provided by small mesopores. This special pore structure shows high adaptability when used as electrode materials for an electric double layer capacitor, especially at high charge-discharge rate. The gravimetric capacitance values of the porous carbon are 425 and 210 F g(-1) and volumetric capacitance values are 242 and 120 F cm(-3) in 1 M H2SO4 and 1 M TEA BF4/AN, respectively. The capacitances even remain at 280 F g(-1) (160 F cm(-3)) at 100 A g(-1) and 156 F g(-1) (90 F cm(-3)) at 50 A g(-1) in the aqueous and organic electrolytes, demonstrating excellent high-rate capacitive performance.

High Energy Density Asymmetric Supercapacitor Based on NiOOH/Ni3S2/3D Graphene and Fe3O4/Graphene Composite Electrodes

PubMed Central

Lin, Tsung-Wu; Dai, Chao-Shuan; Hung, Kuan-Chung

2014-01-01

The application of the composite of Ni3S2 nanoparticles and 3D graphene as a novel cathode material for supercapacitors is systematically investigated in this study. It is found that the electrode capacitance increases by up to 111% after the composite electrode is activated by the consecutive cyclic voltammetry scanning in 1 M KOH. Due to the synergistic effect, the capacitance and the diffusion coefficient of electrolyte ions of the activated composite electrode are ca. 3.7 and 6.5 times higher than those of the Ni3S2 electrode, respectively. Furthermore, the activated composite electrode exhibits an ultrahigh specific capacitance of 3296 F/g and great cycling stability at a current density of 16 A/g. To obtain the reasonable matching of cathode/anode electrodes, the composite of Fe3O4 nanoparticles and chemically reduced graphene oxide (Fe3O4/rGO) is synthesized as the anode material. The Fe3O4/rGO electrode exhibits the specific capacitance of 661 F/g at 1 A/g and excellent rate capability. More importantly, an asymmetric supercapacitor fabricated by two different composite electrodes can be operated reversibly between 0 and 1.6 V and obtain a high specific capacitance of 233 F/g at 5 mV/s, which delivers a maximum energy density of 82.5 Wh/kg at a power density of 930 W/kg. PMID:25449978

Synthesis of Co3O4 nanosheets via electrodeposition followed by ozone treatment and their application to high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Kung, Chung-Wei; Chen, Hsin-Wei; Lin, Chia-Yu; Vittal, R.; Ho, Kuo-Chuan

2012-09-01

A thin film of Co3O4 nanosheets is electrodeposited on a flexible Ti substrate by a one-step potentiostatic method, followed by an UV-ozone treatment for 30 min. The films before and after the UV-ozone treatment are characterized with X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The film is composed of Co(OH)2 before UV-ozone treatment, and of Co3O4 after the treatment. The morphologies of both films are examined by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The obtained films are composed of nanosheets, and there is no change in their sheet-like morphology before and after the UV-ozone treatment. When applied for a supercapacitor, the Co3O4 modified Ti electrode (Co3O4/Ti) shows a far higher capacitance than that of the Co(OH)2 modified Ti electrode. The electrodeposition time and NaOH concentration in the electrolyte are optimized. A remarkably high specific capacitance of 1033.3 F g-1 is obtained for the Co3O4 thin film at a charge-discharge current density of 2.5 A g-1. The long-term stability data shows that there is still 77% of specific capacitance remaining after 3000 repeated charge-discharge cycles. The high specific capacitance and long-term stability suggest the potential use of Co3O4/Ti for making a flexible supercapacitor.

High performance supercapacitors based on three-dimensional ultralight flexible manganese oxide nanosheets/carbon foam composites

NASA Astrophysics Data System (ADS)

He, Shuijian; Chen, Wei

2014-09-01

The syntheses and capacitance performances of ultralight and flexible MnO2/carbon foam (MnO2/CF) hybrids are systematically studied. Flexible carbon foam with a low mass density of 6.2 mg cm-3 and high porosity of 99.66% is simply obtained by carbonization of commercially available and low-cost melamine resin foam. With the high porous carbon foam as framework, ultrathin MnO2 nanosheets are grown through in situ redox reaction between KMnO4 and carbon foam. The three-dimensional (3D) MnO2/CF networks exhibit highly ordered hierarchical pore structure. Attributed to the good flexibility and ultralight weight, the MnO2/CF nanomaterials can be directly fabricated into supercapacitor electrodes without any binder and conductive agents. Moreover, the pseudocapacitance of the MnO2 nanosheets is enhanced by the fast ion diffusion in the three-dimensional porous architecture and by the conductive carbon foam skeleton as well as good contact of carbon/oxide interfaces. Supercapacitor based on the MnO2/CF composite with 3.4% weight percent of MnO2 shows a high specific capacitance of 1270.5 F g-1 (92.7% of the theoretical specific capacitance of MnO2) and high energy density of 86.2 Wh kg-1. The excellent capacitance performance of the present 3D ultralight and flexible nanomaterials make them promising candidates as electrode materials for supercapacitors.

B-Site Cation-Ordered Double-Perovskite Oxide as an Outstanding Electrode Material for Supercapacitive Energy Storage Based on the Anion Intercalation Mechanism.

PubMed

Xu, Zhenye; Liu, Yu; Zhou, Wei; Tade, Moses O; Shao, Zongping

2018-03-21

Perovskite oxides are highly promising electrodes for oxygen-ion-intercalation-type supercapacitors owing to their high oxygen vacancy concentration, oxygen diffusion rate, and tap density. Based on the anion intercalation mechanism, the capacitance is contributed by surface redox reactions and oxygen ion intercalation in the bulk materials. A high concentration of oxygen vacancies is needed because it is the main charge carrier. In this study, we propose a B-site cation-ordered Ba 2 Bi 0.1 Sc 0.2 Co 1.7 O 6-δ as an electrode material with an extremely high oxygen vacancy concentration and oxygen diffusion rate. A maximum capacitance of 1050 F g -1 was achieved, and a high capacitance of 780 F g -1 was maintained even after 3000 charge-discharge cycles at a current density of 1 A g -1 with an aqueous alkaline solution (6 M KOH) electrolyte, indicating an excellent cycling stability. In addition, the specific volumetric capacitance of Ba 2 Bi 0.1 Sc 0.2 Co 1.7 O 6-δ reaches up to 2549.4 F cm -3 based on the dense construction and high tap density (3.2 g cm -3 ). In addition, an asymmetric supercapacitor was constructed using activated carbon as a negative electrode, and it displayed the highest specific energy density of 70 Wh kg -1 at the power density of 787 W kg -1 in this study.

Enhanced Capacitance of Hybrid Layered Graphene/Nickel Nanocomposite for Supercapacitors

NASA Astrophysics Data System (ADS)

Mohd Zaid, Norsaadatul Akmal; Idris, Nurul Hayati

2016-08-01

In this work, Ni nanoparticles were directly decorated on graphene (G) nanosheets via mechanical ball milling. Based on transmission electron microscopy observations, the Ni nanoparticles were well dispersed and attached to the G nanosheet without any agglomerations. Electrochemical results showed that the capacitance of a G/Ni nanocomposite was 275 F g-1 at a current density of 2 A g-1, which is higher than the capacitance of bare G (145 F g-1) and bare Ni (3 F g-1). The G/Ni electrode also showed superior performance at a high current density, exhibiting a capacitance of 190 F g-1 at a current density of 5 A g-1 and a capacitance of 144 F g-1 at a current density of 10 A g-1. The equivalent series resistance for G/Ni nanocomposites also decreased. The enhanced performance of this hybrid supercapacitor is best described by the synergistic effect, i.e. dual charge-storage mechanism, which is demonstrated by electrical double layer and pseudocapacitance materials. Moreover, a high specific surface area and electrical conductivity of the materials enhanced the capacitance. These results indicate that the G/Ni nanocomposite is a potential supercapacitor.

Enhanced Capacitance of Hybrid Layered Graphene/Nickel Nanocomposite for Supercapacitors.

PubMed

Mohd Zaid, Norsaadatul Akmal; Idris, Nurul Hayati

2016-08-24

In this work, Ni nanoparticles were directly decorated on graphene (G) nanosheets via mechanical ball milling. Based on transmission electron microscopy observations, the Ni nanoparticles were well dispersed and attached to the G nanosheet without any agglomerations. Electrochemical results showed that the capacitance of a G/Ni nanocomposite was 275 F g(-1) at a current density of 2 A g(-1), which is higher than the capacitance of bare G (145 F g(-1)) and bare Ni (3 F g(-1)). The G/Ni electrode also showed superior performance at a high current density, exhibiting a capacitance of 190 F g(-1) at a current density of 5 A g(-1) and a capacitance of 144 F g(-1) at a current density of 10 A g(-1). The equivalent series resistance for G/Ni nanocomposites also decreased. The enhanced performance of this hybrid supercapacitor is best described by the synergistic effect, i.e. dual charge-storage mechanism, which is demonstrated by electrical double layer and pseudocapacitance materials. Moreover, a high specific surface area and electrical conductivity of the materials enhanced the capacitance. These results indicate that the G/Ni nanocomposite is a potential supercapacitor.

Preparation of porous carbon spheres from 2-keto-l-gulonic acid mother liquor by oxidation and activation for electric double-layer capacitor application.

PubMed

Hao, Zhi-Qiang; Cao, Jing-Pei; Zhao, Xiao-Yan; Wu, Yan; Zhu, Jun-Sheng; Dang, Ya-Li; Zhuang, Qi-Qi; Wei, Xian-Yong

2018-03-01

A novel strategy is proposed for the increase of specific surface area (SSA) of porous carbon sphere (PCS) by oxidation and activation. 2-keto-l-gulonic acid mother liquor (GAML) as a high-pollution waste has a relatively high value of reutilization. For its high value-added utilization, GAML is used as the precursor for preparation of PCS as carbon-based electrode materials for electric double-layer capacitor. PCS is prepared by hydrothermal carbonization, carbonization and KOH activation, and Fe(NO 3 ) 3 9H 2 O is used as an oxidizing agent during carbonization. The as-prepared PCS has excellent porosity and high SSA of 2478 m 2  g -1 . Meanwhile, the pore structure of PCS can be controlled by the adjustment of carbonization parameters (carbonization temperature and the loading of Fe(NO 3 ) 3 9H 2 O). Besides, the SSA and specific capacitance of PCS can be increased remarkably when Fe(NO 3 ) 3 9H 2 O is added in carbonization. The specific capacitance of PCS can reach 303.7 F g -1 at 40 mA g -1 . PCSs as electrode material have superior electrochemical stability. After 8000 cycles, the capacitance retention is 98.3% at 2 A g -1 . The electric double-layer capacitance of PCS is improved when CS is carbonized with Fe(NO 3 ) 3 9H 2 O, and the economic and environmental benefits are achieved by the effective recycle of GAML. Copyright © 2017 Elsevier Inc. All rights reserved.

Nitrogen-doped mesoporous carbons for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Wu, Kai; Liu, Qiming

2016-08-01

The mesoporous carbons have been synthesized by using α-D(+)-Glucose, D-Glucosamine hydrochloride or their mixture as carbon precursors and mesoporous silicas (SBA-15 or MCF) as hard templates. The as-prepared products show a large pore volume (0.59-0.97 cm3 g-1), high surface areas (352.72-1152.67 m2 g-1) and rational nitrogen content (ca. 2.5-3.9 wt.%). The results of electrochemical tests demonstrate that both heteroatom doping and suitable pore structure play a decisive role in the performance of supercapacitors. The representative sample of SBA-15 replica obtained using D-Glucosamine hydrochloride only exhibits high specific capacitance (212.8 F g-1 at 0.5 A g-1) and good cycle durability (86.1% of the initial capacitance after 2000 cycles) in 6 M KOH aqueous electrolyte, which is attributed to the contribution of double layer capacitance and pseudo-capacitance. The excellent electrochemical performance makes it a promising electrode material for supercapacitors.

Electrospun carbon nanofibers surface-grafted with vapor-grown carbon nanotubes as hierarchical electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Zhou, Zhengping; Wu, Xiang-Fa; Fong, Hao

2012-01-01

This letter reports the fabrication and electrochemical properties of electrospun carbon nanofibers surface-grafted with vapor-grown carbon nanotubes (CNTs) as hierarchical electrodes for supercapacitors. The specific capacitance of the fabricated electrodes was measured up to 185 F/g at the low discharge current density of 625 mA/g; a decrease of 38% was detected at the high discharge current density of 2.5 A/g. The morphology and microstructure of the electrodes were examined by electron microscopy, and the unique connectivity of the hybrid nanomaterials was responsible for the high specific capacitance and low intrinsic contact electric resistance of the hierarchical electrodes.

Effects of adding ethanol to KOH electrolyte on electrochemical performance of titanium carbide-derived carbon

NASA Astrophysics Data System (ADS)

Xu, Jiang; Zhang, Ruijun; Chen, Peng; Ge, Shanhai

2014-01-01

Porous carbide-derived carbons (CDCs) are synthesized from TiC at different chlorination temperatures as electrode materials for electrochemical capacitors. It is found that the microstructure of the produced CDCs has significant influence on both the hydrophilicity in aqueous KOH electrolyte and the resultant electrochemical performance. Because the TiC-CDC synthesized at higher temperature (e.g. 1000 °C) contains well-ordered graphite ribbons, it shows lower hydrophilicity and specific capacitance. It is also found that addition of a small amount of ethanol to KOH electrolyte effectively improves the wettability of the CDCs synthesized at higher temperature and the corresponding specific capacitance. Compared with the CDC synthesized at 600 °C, the CDC synthesized at 1000 °C shows fast ion transport and excellent capacitive behavior in KOH electrolyte with addition of ethanol because of the existences of mesopores and high specific surface area.

Reduced Graphene Oxide/Carbon Nanotube Composites as Electrochemical Energy Storage Electrode Applications.

PubMed

Yang, Wenyao; Chen, Yan; Wang, Jingfeng; Peng, Tianjun; Xu, Jianhua; Yang, Bangchao; Tang, Ke

2018-06-15

We demonstrate an electrochemical reduction method to reduce graphene oxide (GO) to electrochemically reduced graphene oxide (ERGO) with the assistance of carbon nanotubes (CNTs). The faster and more efficient reduction of GO can be achieved after proper addition of CNTs into GO during the reduction process. This nanotube/nanosheet composite was deposited on electrode as active material for electrochemical energy storage applications. It has been found that the specific capacitance of the composite film was strongly affected by the mass ratio of GO/CNTs and the scanning ratio of cyclic voltammetry. The obtained ERGO/CNT composite electrode exhibited a 279.4 F/g-specific capacitance and showed good cycle rate performance with the evidence that the specific capacitance maintained above 90% after 6000 cycles. The synergistic effect between ERGO and CNTs as well as crossing over of CNTs into ERGO is attributed to the high electrochemical performance of composite electrode.

Nanoporous metal/oxide hybrid electrodes for electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Lang, Xingyou; Hirata, Akihiko; Fujita, Takeshi; Chen, Mingwei

2011-04-01

Electrochemical supercapacitors can deliver high levels of electrical power and offer long operating lifetimes, but their energy storage density is too low for many important applications. Pseudocapacitive transition-metal oxides such as MnO2 could be used to make electrodes in such supercapacitors, because they are predicted to have a high capacitance for storing electrical charge while also being inexpensive and not harmful to the environment. However, the poor conductivity of MnO2 (10-5-10-6 S cm-1) limits the charge/discharge rate for high-power applications. Here, we show that hybrid structures made of nanoporous gold and nanocrystalline MnO2 have enhanced conductivity, resulting in a specific capacitance of the constituent MnO2 (~1,145 F g-1) that is close to the theoretical value. The nanoporous gold allows electron transport through the MnO2, and facilitates fast ion diffusion between the MnO2 and the electrolytes while also acting as a double-layer capacitor. The high specific capacitances and charge/discharge rates offered by such hybrid structures make them promising candidates as electrodes in supercapacitors, combining high-energy storage densities with high levels of power delivery.

Nanoporous metal/oxide hybrid electrodes for electrochemical supercapacitors.

PubMed

Lang, Xingyou; Hirata, Akihiko; Fujita, Takeshi; Chen, Mingwei

2011-04-01

Electrochemical supercapacitors can deliver high levels of electrical power and offer long operating lifetimes, but their energy storage density is too low for many important applications. Pseudocapacitive transition-metal oxides such as MnO(2) could be used to make electrodes in such supercapacitors, because they are predicted to have a high capacitance for storing electrical charge while also being inexpensive and not harmful to the environment. However, the poor conductivity of MnO(2) (10(-5)-10(-6) S cm(-1)) limits the charge/discharge rate for high-power applications. Here, we show that hybrid structures made of nanoporous gold and nanocrystalline MnO(2) have enhanced conductivity, resulting in a specific capacitance of the constituent MnO(2) (~1,145 F g(-1)) that is close to the theoretical value. The nanoporous gold allows electron transport through the MnO(2), and facilitates fast ion diffusion between the MnO(2) and the electrolytes while also acting as a double-layer capacitor. The high specific capacitances and charge/discharge rates offered by such hybrid structures make them promising candidates as electrodes in supercapacitors, combining high-energy storage densities with high levels of power delivery.

Reduced graphene oxide and vertically aligned carbon nanotubes superhydrophilic films for supercapacitors devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zanin, H., E-mail: hudsonzanin@gmail.com; Departamento de Semicondutores, Instrumentos e Fotônica, Faculdade de Engenharia Elétrica e Computação, Universidade Estadual de Campinas, UNICAMP, Campinas 13083-970; Saito, E., E-mail: esaito135@gmail.com

2014-01-01

Graphical abstract: - Highlights: • Graphene nanosheets were produced onto wire rods. • RGO and VACNT-O were evaluated and compared as supercapacitor electrode. • RGO and VACNT-O have structural and electrochemical properties quite similars. • The materials present good specific capacitance, energy storage and power delivery. - Abstract: Reduced graphene oxide (RGO) and vertically aligned carbon nanotubes (VACNT) superhydrophilic films were prepared by chemical vapor deposition techniques for electrical energy storage investigations. These electrodes were characterized in terms of their material and electrochemical properties by scanning electron microscopy (SEM), surface wettability, Fourier transform infrared spectroscopy (FTIR), energy dispersive and Ramanmore » spectroscopies, cyclic voltammetry (CV) and galvanostatic charge–discharge. We observed several physical structural and electrochemical similarities between these carbon-based materials with particular attention to very good specific capacitance, ultra-high energy storage and fast power delivery. Our results showed that the main difference between specific capacitance values is attributed to pseudocapacitive contribution and high density of multiwall nanotubes tips. In this work we have tested a supercapacitor device using the VACNT electrodes.« less

PolyHIPE Derived Freestanding 3D Carbon Foam for Cobalt Hydroxide Nanorods Based High Performance Supercapacitor

NASA Astrophysics Data System (ADS)

Patil, Umakant M.; Ghorpade, Ravindra V.; Nam, Min Sik; Nalawade, Archana C.; Lee, Sangrae; Han, Haksoo; Jun, Seong Chan

2016-10-01

The current paper describes enhanced electrochemical capacitive performance of chemically grown Cobalt hydroxide (Co(OH)2) nanorods (NRs) decorated porous three dimensional graphitic carbon foam (Co(OH)2/3D GCF) as a supercapacitor electrode. Freestanding 3D porous GCF is prepared by carbonizing, high internal phase emulsion (HIPE) polymerized styrene and divinylbenzene. The PolyHIPE was sulfonated and carbonized at temperature up to 850 °C to obtain graphitic 3D carbon foam with high surface area (389 m2 g-1) having open voids (14 μm) interconnected by windows (4 μm) in monolithic form. Moreover, entangled Co(OH)2 NRs are anchored on 3D GCF electrodes by using a facile chemical bath deposition (CBD) method. The wide porous structure with high specific surface area (520 m2 g-1) access offered by the interconnected 3D GCF along with Co(OH)2 NRs morphology, displays ultrahigh specific capacitance, specific energy and power. The Co(OH)2/3D GCF electrode exhibits maximum specific capacitance about ~1235 F g-1 at ~1 A g-1 charge-discharge current density, in 1 M aqueous KOH solution. These results endorse potential applicability of Co(OH)2/3D GCF electrode in supercapacitors and signifies that, the porous GCF is a proficient 3D freestanding framework for loading pseudocapacitive nanostructured materials.

Ag incorporated Mn3O4/AC nanocomposite based supercapacitor devices with high energy density and power density.

PubMed

Nagamuthu, S; Vijayakumar, S; Muralidharan, G

2014-12-14

Silver incorporated Mn3O4/amorphous carbon (AC) nanocomposites are synthesized by a green chemistry method. X-ray diffraction studies revealed the structural changes in Mn3O4/AC nanocomposites attributable to the addition of silver. Cyclic voltammetry, charge-discharge and ac-impedance studies indicated that the Ag-Mn3O4/AC-5 electrode was the most suitable candidate for supercapacitor applications. From the galvanostatic charge-discharge studies, a higher specific capacitance of 981 F g(-1) at a specific current of 1 A g(-1) was obtained. An Ag-Mn3O4/AC-symmetric supercapacitor consisting of an Ag-incorporated Mn3O4/AC composite as an anode as well as a cathode, and an asymmetric supercapacitor consisting of an Ag-incorporated Mn3O4/AC composite as a cathode and an activated carbon as an anode have been fabricated. The symmetric device exhibits a specific cell capacitance of 72 F g(-1) at a specific current of 1 A g(-1) whereas the asymmetric device delivers a specific cell capacitance of 180 F g(-1) at a high current rate of 10 A g(-1). The asymmetric supercapacitor device yields a high energy density of 81 W h kg(-1). This is higher than that of lead acid batteries and comparable with that of nickel hydride batteries.

A high-capacity carbon prepared from renewable chicken feather biopolymer for supercapacitors

NASA Astrophysics Data System (ADS)

Wang, Qiang; Cao, Qi; Wang, Xianyou; Jing, Bo; Kuang, Hao; Zhou, Ling

2013-03-01

Micropopous chicken feather carbon (CFC) severing as electrode materials for the first time is prepared via the activation with KOH agent to different extents. The structure and electrochemical properties of CFC materials are characterized with N2 adsorption/desorption measurements, X-ray diffraction (XRD), transmission electron microscope (TEM), cyclic voltammetry (CV), galvanostatic charge/discharge cycling and electrochemical impedance spectroscopy (EIS). The obtained results show that CFC activated by KOH with KOH/CFC weight ratio of 4/1 (CFCA4) possesses the specific surface area of 1839 m2 g-1, average micropore diameter of 1.863 nm, and exhibits the highest initial specific capacitance of 302 F g-1 at current density of 1 A g-1 in 1 M H2SO4, and that even after 5000 cycles, CFCA4 specific capacitance is still as high as 253 F g-1. Furthermore, CFCA4 also delivers specific capacitance of 181 F g-1 at current density of 5 A g-1 and 168 F g-1 at current density of 10 A g-1. Accordingly, the microporous activated carbon material derived from chicken feather provides favorable prospect in electrode materials application in supercapacitors.

Three-dimensional hierarchical NiCo2O4 nanowire@Ni3S2 nanosheet core/shell arrays for flexible asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Bo; Kong, Dezhi; Huang, Zhi Xiang; Mo, Runwei; Wang, Ye; Han, Zhaojun; Cheng, Chuanwei; Yang, Hui Ying

2016-05-01

Three-dimensional (3D) hierarchical NiCo2O4@Ni3S2 core/shell arrays on Ni foam were synthesized by a facile, stepwise synthesis approach. The 3D heterogeneous NiCo2O4 nanostructure forms an interconnected web-like scaffold and serves as the core for the Ni3S2 shell. The as-prepared NiCo2O4@Ni3S2 nanowire array (NWA) electrodes exhibited excellent electrochemical performance, such as high specific areal capacitance and excellent cycling stability. The specific areal capacitance of 3.0 F cm-2 at a current density of 5 mA cm-2 is among the highest values and the only 6.7% capacitance decay after 10 000 cycles demonstrates the excellent cycling stability. A flexible asymmetric supercapacitor (ASC) was fabricated with activated carbon (AC) as the anode and the obtained NiCo2O4@Ni3S2 NWAs as the cathode. The ASC device exhibited a high energy density of 1.89 mW h cm-3 at 5.81 W cm-3 and a high power density of 56.33 W cm-3 at 0.94 mW h cm-3. As a result, the hybrid nanoarchitecture opens a new way to design high performance electrodes for electrochemical energy storage applications.Three-dimensional (3D) hierarchical NiCo2O4@Ni3S2 core/shell arrays on Ni foam were synthesized by a facile, stepwise synthesis approach. The 3D heterogeneous NiCo2O4 nanostructure forms an interconnected web-like scaffold and serves as the core for the Ni3S2 shell. The as-prepared NiCo2O4@Ni3S2 nanowire array (NWA) electrodes exhibited excellent electrochemical performance, such as high specific areal capacitance and excellent cycling stability. The specific areal capacitance of 3.0 F cm-2 at a current density of 5 mA cm-2 is among the highest values and the only 6.7% capacitance decay after 10 000 cycles demonstrates the excellent cycling stability. A flexible asymmetric supercapacitor (ASC) was fabricated with activated carbon (AC) as the anode and the obtained NiCo2O4@Ni3S2 NWAs as the cathode. The ASC device exhibited a high energy density of 1.89 mW h cm-3 at 5.81 W cm-3 and a high power density of 56.33 W cm-3 at 0.94 mW h cm-3. As a result, the hybrid nanoarchitecture opens a new way to design high performance electrodes for electrochemical energy storage applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02600a

Electrochemically Active Polyaniline (PANi) Coated Carbon Nanopipes and PANi Nanofibers Containing Composite.

PubMed

Ramana, G Venkata; Kumar, P Sampath; Srikanth, Vadali V S S; Padya, Balaji; Jain, P K

2015-02-01

A composite constituted by carbon nanopipes (CNPs) and polyaniline nanofibers (PANi NFs) is synthesized using in-situ chemical oxidative polymerization. Owing to its electrochemical activity the composite is found to be suitable as a working electrode material in hybrid type supercapacitors. Microstructural and phase analyses of the composite showed that (i) CNP surfaces are coated with PANi and (ii) PANi coated CNPs are distributed among PANi NFs. The composite shows an excellent electrochemical activity and a high specific capacitance of ~224.39 F/g. The electro-chemical activity of the composite is explicated in correlation with crystallinity, intrinsic oxidation state, and doping degree of PANi in the composite. The electro-chemical activity of the composite is also explicated in correlation with BET surface area and ordered meso-porosity pertaining to the composite. Charge/discharge curves indicate that the specific capacitance of the composite is a result of electric double-layer capacitance offered by CNPs and Faradaic pseudo capacitance offered by PANi NFs.

A p-nitroaniline redox-active solid-state electrolyte for battery-like electrochemical capacitive energy storage combined with an asymmetric supercapacitor based on metal oxide functionalized β-polytype porous silicon carbide electrodes.

PubMed

Kim, Myeongjin; Yoo, Jeeyoung; Kim, Jooheon

2017-05-23

A unique redox active flexible solid-state asymmetric supercapacitor with ultra-high capacitance and energy density was fabricated using a composite comprising MgCo 2 O 4 nanoneedles and micro and mesoporous silicon carbide flakes (SiCF) (SiCF/MgCo 2 O 4 ) as the positive electrode material. Due to the synergistic effect of the two materials, this hybrid electrode has a high specific capacitance of 516.7 F g -1 at a scan rate of 5 mV s -1 in a 1 M KOH aqueous electrolyte. To obtain a reasonable matching of positive and negative electrode pairs, a composite of Fe 3 O 4 nanoparticles and SiCF (SiCF/Fe 3 O 4 ) was synthesized for use as a negative electrode material, which shows a high capacitance of 423.2 F g -1 at a scan rate of 5 mV s -1 . Therefore, by pairing the SiCF/MgCo 2 O 4 positive electrode and the SiCF/Fe 3 O 4 negative electrode with a redox active quasi-solid-state PVA-KOH-p-nitroaniline (PVA-KOH-PNA) gel electrolyte, a novel solid-state asymmetric supercapacitor device was assembled. Because of the synergistic effect between the highly porous SiCF and the vigorous redox-reaction of metal oxides, the hybrid nanostructure electrodes exhibited outstanding charge storage and transport. In addition, the redox active PVA-KOH-PNA electrolyte adds additional pseudocapacitance, which arises from the nitro-reduction and oxidation and reduction process of the reduction product of p-phenylenediamine, resulting in an enhancement of the capacitance (a specific capacitance of 161.77 F g -1 at a scan rate of 5 mV s -1 ) and energy density (maximum energy density of 72.79 Wh kg -1 at a power density of 727.96 W kg -1 ).

Facile one-step synthesis of nanocomposite based on carbon nanotubes and Nickel-Aluminum layered double hydroxides with high cycling stability for supercapacitors.

PubMed

Bai, Caihui; Sun, Shiguo; Xu, Yongqian; Yu, Ruijin; Li, Hongjuan

2016-10-15

Nickel-Aluminum Layered Double Hydroxide (NiAl-LDH) and nanocomposite of Carbon Nanotubes (CNTs) and NiAl-LDH (CNTs/NiAl-LDH) were prepared by using a facile one-step homogeneous precipitation approach. The morphology, structure and electrochemical properties of the as-prepared CNTs/NiAl-LDH nanocomposite were then systematically studied. According to the galvanostatic charge-discharge curves, the CNTs/NiAl-LDH nanocomposite exhibited a high specific capacitance of 694Fg(-1) at the 1Ag(-1). Furthermore, the specific capacitance of the CNTs/NiAl-LDH nanocomposite still retained 87% when the current density was increased from 1 to 10Ag(-1). These results indicated that the CNTs/NiAl-LDH nanocomposite displayed a higher specific capacitance and rate capability than pure NiAl-LDH. And the participation of CNTs in the NiAl-LDH composite improved the electrochemical properties. Additionally, the capacitance of the CNTs/NiAl-LDH nanocomposite kept at least 92% after 3000cycles at 20Ag(-1), suggesting that the nanocomposite exhibited excellent cycling durability. This strategy provided a facile and effective approach for the synthesis of nanocomposite based on CNTs and NiAl-LDH with enhanced supercapacitor behaviors, which can be potentially applied in energy storage conversion devices. Copyright © 2016 Elsevier Inc. All rights reserved.

Interfacial Engineered Polyaniline/Sulfur-Doped TiO2 Nanotube Arrays for Ultralong Cycle Lifetime Fiber-Shaped, Solid-State Supercapacitors.

PubMed

Li, Chun; Wang, Zhuanpei; Li, Shengwen; Cheng, Jianli; Zhang, Yanning; Zhou, Jingwen; Yang, Dan; Tong, Dong-Ge; Wang, Bin

2018-05-30

Fiber-shaped supercapacitors (FSCs) have great promises in wearable electronics applications. However, the limited specific surface area and inadequate structural stability caused by the weak interfacial interactions of the electrodes result in relatively low specific capacitance and unsatisfactory cycle lifetime. Herein, solid-state FSCs with high energy density and ultralong cycle lifetime based on polyaniline (PANI)/sulfur-doped TiO 2 nanotube arrays (PANI/S-TiO 2 ) are fabricated by interfacial engineering. The experimental results and ab initio calculations reveal that S doping can effectively promote the conductivity of titania nanotubes and increase the binding energy of PANI anchored on the electrode surface, leading to a much stronger binding of PANI on the surface of the electrode and excellent electrode structure stability. As a result, the FSCs using the PANI/S-TiO 2 electrodes deliver a high specific capacitance of 91.9 mF cm -2 , a capacitance retention of 93.78% after 12 000 charge-discharge cycles, and an areal energy density of 3.2 μW h cm -2 . Meanwhile, the all-solid-state FSC device retains its excellent flexibility and stable electrochemical capacitance even after bending 150 cycles. The enhanced performances of FSCs could be attributed to the large surface area, reduced ion diffusion path, improved electrical conductivity, and engineered interfacial interaction of the rationally designed electrodes.

NiCoO2 flowers grown on the aligned-flakes coated Ni foam for application in hybrid energy storage

NASA Astrophysics Data System (ADS)

Xu, Xiaoyang; Zhao, Huilin; Zhou, JingKuo; Xue, Ruinan; Gao, Jianping

2016-10-01

Many NiCoO2 flowers with an average diameter of about 4 μm were grown on the NiCoO2 flakes coated Ni foam (denoted as NiCoO2/Ni foam) through a simple hydrothermal method and confirmed by scanning and transmission electron microscopies, X-ray diffraction and X-ray photoelectron spectrum measurements. The NiCoO2/Ni foam with high specific area and porosity was directly used as the working electrode without any binders. The measured specific capacitance of NiCoO2 grown on Ni foam is 756 F/g at 0.75 A/g using a three-electrode setup in 1 M KOH. Considering the high capacity of NiCoO2 and the good stability of rGO, the NiCoO2/Ni foam//rGO hybrid supercapacitor combining NiCoO2/Ni foam and rGO shows very good properties, such as high specific capacitance (82 F/g at 2 A/g based on the total mass of active materials), high energy density (25.7 Wh/kg at 1500 W/kg based on the total mass of active materials), good stability (about 90% capacitance retention after 2000-cycle at 100 mV/s), and low charge ion transfer resistance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Ying; Lee, Sungsik; Brown, Dennis E.

Ultrafine manganese oxide-decorated carbon nanofibers (MnOn-CNF) as a new type of electrode materials are facilely fabricated by direct conversion of Mn, Zn-trimesic acid (H3BTC) metal organic framework fibers (Mn-ZnBTC). The construction and evolution of Mn-ZnBTC precursors are investigated by SEM and in situ high-energy XRD. The manganese oxides are highly dispersed onto the porous carbon nanofibers formed simultaneously, verified by TEM, X-ray absorption fine structure (XAFS), Raman, ICP-AES and N2 adsorption techniques. As expected, the resulting MnOn-CNF composites are highly stable, and can be cycled up to 5000 times with a high capacitance retention ratio of 98% in electrochemical capacitormore » measurements. They show a high capacitance of up to 179 F g–1 per mass of the composite electrode, and a remarkable capacitance of up to 18290 F g–1 per active mass of the manganese(IV) oxide, significantly exceeding the theoretical specific capacitance of manganese(IV) oxide (1370 F g–1). The maximum energy density is up to 19.7 Wh kg–1 at the current density of 0.25 A g–1, even orders higher than those of reported electric double-layer capacitors and pseudocapacitors. The excellent capacitive performance can be ascribed to the joint effect of easy accessibility, high porosity, tight contact and superior conductivity integrated in final MnOn-CNF composites.« less

MnO2 Nanorods Intercalating Graphene Oxide/Polyaniline Ternary Composites for Robust High-Performance Supercapacitors

PubMed Central

Han, Guangqiang; Liu, Yun; Zhang, Lingling; Kan, Erjun; Zhang, Shaopeng; Tang, Jian; Tang, Weihua

2014-01-01

New ternary composites of MnO2 nanorods, polyaniline (PANI) and graphene oxide (GO) have been prepared by a two-step process. The 100 nm-long MnO2 nanorods with a diameter ~20 nm are conformably coated with PANI layers and fastened between GO layers. The MnO2 nanorods incorporated ternary composites electrode exhibits significantly increased specific capacitance than PANI/GO binary composite in supercapacitors. The ternary composite with 70% MnO2 exhibits a highest specific capacitance reaching 512 F/g and outstanding cycling performance, with ~97% capacitance retained over 5000 cycles. The ternary composite approach offers an effective solution to enhance the device performance of metal-oxide based supercapacitors for long cycling applications. PMID:24769835

A Novel Layered Sedimentary Rocks Structure of the Oxygen-Enriched Carbon for Ultrahigh-Rate-Performance Supercapacitors.

PubMed

Zhang, Lin-Lin; Li, Huan-Huan; Shi, Yan-Hong; Fan, Chao-Ying; Wu, Xing-Long; Wang, Hai-Feng; Sun, Hai-Zhu; Zhang, Jing-Ping

2016-02-17

In this paper, gelatin as a natural biomass was selected to successfully prepare an oxygen-enriched carbon with layered sedimentary rocks structure, which exhibited ultrahigh-rate performance and excellent cycling stability as supercapacitors. The specific capacitance reached 272.6 F g(-1) at 1 A g(-1) and still retained 197.0 F g(-1) even at 100 A g(-1) (with high capacitance retention of 72.3%). The outstanding electrochemical performance resulted from the special layered structure with large surface area (827.8 m(2) g(-1)) and high content of oxygen (16.215 wt %), which effectively realized the synergistic effects of the electrical double-layer capacitance and pseudocapacitance. Moreover, it delivered an energy density of 25.3 Wh kg(-1) even with a high power density of 34.7 kW kg(-1) and ultralong cycling stability (with no capacitance decay even over 10,000 cycles at 2 A g(-1)) in a symmetric supercapacitor, which are highly desirable for their practical application in energy storage devices and conversion.

Transforming Pristine Carbon Fiber Tows into High Performance Solid-State Fiber Supercapacitors.

PubMed

Yu, Dingshan; Zhai, Shengli; Jiang, Wenchao; Goh, Kunli; Wei, Li; Chen, Xudong; Jiang, Rongrong; Chen, Yuan

2015-09-02

A facile activation strategy can transform pristine carbon fiber tows into high-performance fiber electrodes with a specific capacitance of 14.2 F cm(-3) . The knottable fiber supercapacitor shows an energy density of 0.35 mW h cm(-3) , an ultrahigh power density of 3000 mW cm(-3) , and a remarkable capacitance retention of 68%, when the scan rate increases from 10 to 1000 mV s(-1) . © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Free-standing porous manganese dioxide/graphene composite films for high performance supercapacitors.

PubMed

Guo, Wang-Huan; Liu, Teng-Jiao; Jiang, Peng; Zhang, Zhan-Jun

2015-01-01

A simple hard template method and hydrothermal process have been employed to fabricate a self-standing hierarchical porous MnO2/graphene film. Thus-constructed electrode materials for binder-free supercapacitors exhibit a high specific capacitance of 266.3 F g(-1) at the density of 0.2 A g(-1). Moreover, the two-electrode device demonstrates an excellent rate capability and cycling stability with capacitance retention of 85.1% after 2000 charge-discharge cycles at a current density of 1 A g(-1). The porous nanostructured design can effectively improve the specific surface areas and account for the shorter relaxation time for the electrodes, resulting in a high electrochemical performance. Copyright © 2014 Elsevier Inc. All rights reserved.

Facile synthesis of Mesoporouscobalt Hexacyanoferrate Nanocubes for High-Performance Supercapacitors

PubMed Central

2017-01-01

Mesoporous cobalt hexacyanoferrate nanocubes (meso–CoHCF) were prepared for the first time through a facile sacrificial template method. The CoHCF mesostructures possess a high specific surface area of 548.5 m2·g−1 and a large amount of mesopores, which enable fast mass transport of electrolyte and abundant energy storage sites. When evaluated as supercapacitor materials, the meso–CoHCF materials exhibit a high specific capacitance of 285 F·g−1, good rate capability and long cycle life with capacitance retention of 92.9% after 3000 cycles in Na2SO4 aqueous electrolyte. The excellent electrochemical properties demonstrate the rational preparation of mesoporous prussian blue and its analogues for energy storage applications. PMID:28825671

Graphene oxide-dispersed pristine CNTs support for MnO2 nanorods as high performance supercapacitor electrodes.

PubMed

You, Bo; Li, Na; Zhu, Hongying; Zhu, Xiaolan; Yang, Jun

2013-03-01

A MnO2 -CNT-graphene oxide (MCGO) nanocomposite is fabricated using graphene oxide (GO) as a surfactant to directly disperse pristine carbon nanotubes (CNTs) for the subsequent deposition of MnO2 nanorods. The resulting MCGO nanocomposite is used as a supercapacitor electrode that shows ideal capacitive behavior (i.e., rectangular-shaped cyclic voltammograms), large specific capacitance (4.7 times higher than that of free MnO2 ) even at high mass loading (3.0 mg cm(-2) ), high energy density (30.4-14.2 Wh kg(-1) ), large power density (2.6-50.5 kW kg(-1) ), and still retains approximately 94 % of the initial specific capacitance after 1000 cycles. The advanced capacity, rate capability, and cycling stability may be attributed to the unique architecture, excellent ion wettability of GO with enriched oxygen-containing functional groups, high conductivity of CNTs, and their synergistic effects when combined with the other components. The results suggest that the MnO2 -CNT-GO hybrid nanocomposite architecture is very promising for next generation high-performance energy storage devices. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microwave Assisted Synthesis of Porous NiCo2O4 Microspheres: Application as High Performance Asymmetric and Symmetric Supercapacitors with Large Areal Capacitance

PubMed Central

Khalid, Syed; Cao, Chuanbao; Wang, Lin; Zhu, Youqi

2016-01-01

Large areal capacitance is essentially required to integrate the energy storage devices at the microscale electronic appliances. Energy storage devices based on metal oxides are mostly fabricated with low mass loading per unit area which demonstrated low areal capacitance. It is still a challenge to fabricate supercapacitor devices of porous metal oxides with large areal capacitance. Herein we report microwave method followed by a pyrolysis of the as-prepared precursor is used to synthesize porous nickel cobaltite microspheres. Porous NiCo2O4 microspheres are capable to deliver large areal capacitance due to their high specific surface area and small crystallite size. The facile strategy is successfully demonstrated to fabricate aqueous-based asymmetric & symmetric supercapacitor devices of porous NiCo2O4 microspheres with high mass loading of electroactive materials. The asymmetric & symmetric devices exhibit maximum areal capacitance and energy density of 380 mF cm−2 & 19.1 Wh Kg−1 and 194 mF cm−2 & 4.5 Wh Kg−1 (based on total mass loading of 6.25 & 6.0 mg) respectively at current density of 1 mA cm−2. The successful fabrication of symmetric device also indicates that NiCo2O4 can also be used as the negative electrode material for futuristic asymmetric devices. PMID:26936283

Microwave Assisted Synthesis of Porous NiCo2O4 Microspheres: Application as High Performance Asymmetric and Symmetric Supercapacitors with Large Areal Capacitance

NASA Astrophysics Data System (ADS)

Khalid, Syed; Cao, Chuanbao; Wang, Lin; Zhu, Youqi

2016-03-01

Large areal capacitance is essentially required to integrate the energy storage devices at the microscale electronic appliances. Energy storage devices based on metal oxides are mostly fabricated with low mass loading per unit area which demonstrated low areal capacitance. It is still a challenge to fabricate supercapacitor devices of porous metal oxides with large areal capacitance. Herein we report microwave method followed by a pyrolysis of the as-prepared precursor is used to synthesize porous nickel cobaltite microspheres. Porous NiCo2O4 microspheres are capable to deliver large areal capacitance due to their high specific surface area and small crystallite size. The facile strategy is successfully demonstrated to fabricate aqueous-based asymmetric & symmetric supercapacitor devices of porous NiCo2O4 microspheres with high mass loading of electroactive materials. The asymmetric & symmetric devices exhibit maximum areal capacitance and energy density of 380 mF cm-2 & 19.1 Wh Kg-1 and 194 mF cm-2 & 4.5 Wh Kg-1 (based on total mass loading of 6.25 & 6.0 mg) respectively at current density of 1 mA cm-2. The successful fabrication of symmetric device also indicates that NiCo2O4 can also be used as the negative electrode material for futuristic asymmetric devices.

Two-dimensional nickel hydroxide nanosheets as high performance pseudo-capacitor electrodes

NASA Astrophysics Data System (ADS)

Bhat, Karthik S.; Nagaraja, H. S.

2018-04-01

Electrochemical supercapacitor is a vital technology for the progress of consistent energy harvesting devices. Herein, we report the fabrication of supercapacitor electrodes based on nickel hydroxide nanosheets synthesized via one-pot hydrothermal method. Structure and shape of synthesized materials were analyzed with XRD and SEM measurements. Pseudo-capacitive performances of the fabricated electrodes were evaluated through cyclic voltammetry and galvanostatic charge-discharge measurements with three-electrode configurations. Results indicated the specific capacitance of l80 F g-1 at 5 mV s-1 scan rate and complimented with capacitance retention of 76% for l500 cycles.

Bacterial cellulose-based sheet-like carbon aerogels for the in situ growth of nickel sulfide as high performance electrode materials for asymmetric supercapacitors.

PubMed

Zuo, Lizeng; Fan, Wei; Zhang, Youfang; Huang, Yunpeng; Gao, Wei; Liu, Tianxi

2017-03-30

Electroactive materials, such as nickel sulfide (NiS), with high theoretical capacities have attracted broad interest to fabricate highly efficient supercapacitors. Preventing aggregation and increasing the conductivity of NiS particles are key challenging tasks to fully achieve excellent electrochemical properties of NiS. One effective approach to solve these problems is to combine NiS with highly porous and conductive carbon materials such as carbon aerogels. In this study, a green and facile method for the in situ growth of NiS particles on bacterial cellulose (BC)-derived sheet-like carbon aerogels (CAs) has been reported. CA prepared by the dissolution-gelation-carbonization process was used as a framework to construct NiS/CA composite aerogels with NiS uniformly decorated on the pore walls of CA. It was found that the NiS/CA composite aerogel electrodes exhibit excellent capacitive performance with high specific capacitance (1606 F g -1 ), good rate capacitance retention (69% at 10 A g -1 ), and enhanced cycling stability (91.2% retention after 10 000 continuous cyclic voltammetry cycles at 100 mV s -1 ). Furthermore, asymmetric supercapacitors (ASCs) were constructed utilizing NiS/CA composite and CA as the positive and negative electrode materials, respectively. Through the synergistic effect of three-dimensional porous structures and conductive networks derived from CA and the high capacitive performance offered by NiS, the ASC device exhibited an energy density of ∼21.5 Wh kg -1 and a power density of 700 W kg -1 at the working voltage of 1.4 V in 2 M KOH aqueous solution. The ASC device also showed excellent long-term cycle stability with ∼87.1% specific capacitance retention after 10 000 cycles of cyclic voltammetry scans. Therefore, the NiS/CA composite shows great potential as a promising alternative to high-performance electrode materials for supercapacitors.

Plasma-induced highly efficient synthesis of boron doped reduced graphene oxide for supercapacitors.

PubMed

Li, Shaobo; Wang, Zhaofeng; Jiang, Hanmei; Zhang, Limei; Ren, Jingzheng; Zheng, Mingtao; Dong, Lichun; Sun, Luyi

2016-09-21

In this work, we presented a novel route to synthesize boron doped reduced graphene oxide (rGO) by using the dielectric barrier discharge (DBD) plasma technology under ambient conditions. The doping of boron (1.4 at%) led to a significant improvement in the capacitance of rGO and supercapacitors based on the as-synthesized B-rGO exhibited an outstanding specific capacitance.

Few-layered MoSe2 nanosheets as an advanced electrode material for supercapacitors.

PubMed

Balasingam, Suresh Kannan; Lee, Jae Sung; Jun, Yongseok

2015-09-21

We report the synthesis of few-layered MoSe2 nanosheets using a facile hydrothermal method and their electrochemical charge storage behavior. A systematic study of the structure and morphology of the as-synthesized MoSe2 nanosheets was performed. The downward peak shift in the Raman spectrum and the high-resolution transmission electron microscopy images confirmed the formation of few-layered nanosheets. The electrochemical energy-storage behavior of MoSe2 nanosheets was also investigated for supercapacitor applications in a symmetric cell configuration. The MoSe2 nanosheet electrode exhibited a maximum specific capacitance of 198.9 F g(-1) and the symmetric device showed 49.7 F g(-1) at a scan rate of 2 mV s(-1). A capacitance retention of approximately 75% was observed even after 10 000 cycles at a high charge-discharge current density of 5 A g(-1). The two-dimensional MoSe2 nanosheets exhibited a high specific capacitance and good cyclic stability, which makes it a promising electrode material for supercapacitor applications.

Supercapacitor electrode materials with hierarchically structured pores from carbonization of MWCNTs and ZIF-8 composites.

PubMed

Li, Xueqin; Hao, Changlong; Tang, Bochong; Wang, Yue; Liu, Mei; Wang, Yuanwei; Zhu, Yihua; Lu, Chenguang; Tang, Zhiyong

2017-02-09

Due to their high specific surface area and good electric conductivity, nitrogen-doped porous carbons (NPCs) and carbon nanotubes (CNTs) have attracted much attention for electrochemical energy storage applications. In the present work, we firstly prepared MWCNT/ZIF-8 composites by decoration of zeolitic imidazolate frameworks (ZIF-8) onto the surface of multi-walled CNTs (MWCNTs), then obtained MWCNT/NPCs by the direct carbonization of MWCNT/ZIF-8. By controlling the reaction conditions, MWCNT/ZIF-8 with three different particle sizes were synthesized. The effect of NPCs size on capacitance performance has been evaluated in detail. The MWCNT/NPC with large-sized NPC (MWCNT/NPC-L) displayed the highest specific capacitance of 293.4 F g -1 at the scan rate of 5 mV s -1 and only lost 4.2% of capacitance after 10 000 cyclic voltammetry cycles, which was attributed to the hierarchically structured pores, N-doping and high electrical conductivity. The studies of symmetric two-electrode supercapacitor cells also confirmed MWCNT/NPC-L as efficient electrode materials that have good electrochemical performance, especially for high-rate applications.

High-Potential Metalless Nanocarbon Foam Supercapacitors Operating in Aqueous Electrolyte.

PubMed

Liu, Chueh; Li, Changling; Ahmed, Kazi; Mutlu, Zafer; Lee, Ilkeun; Zaera, Francisco; Ozkan, Cengiz S; Ozkan, Mihrimah

2018-04-01

Light-weight graphite foam decorated with carbon nanotubes (dia. 20-50 nm) is utilized as an effective electrode without binders, conductive additives, or metallic current collectors for supercapacitors in aqueous electrolyte. Facile nitric acid treatment renders wide operating potentials, high specific capacitances and energy densities, and long lifespan over 10 000 cycles manifested as 164.5 and 111.8 F g -1 , 22.85 and 12.58 Wh kg -1 , 74.6% and 95.6% capacitance retention for 2 and 1.8 V, respectively. Overcharge protection is demonstrated by repetitive cycling between 2 and 2.5 V for 2000 cycles without catastrophic structural demolition or severe capacity fading. Graphite foam without metallic strut possessing low density (≈0.4-0.45 g cm -3 ) further reduces the total weight of the electrode. The thorough investigation of the specific capacitances and coulombic efficiencies versus potential windows and current densities provides insights into the selection of operation conditions for future practical devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A porous carbon material from pyrolysis of fructus cannabis’s shells for supercapacitor electrode application

NASA Astrophysics Data System (ADS)

Li, Kai; Zhang, Wei-Bin; Zhao, Zhi-Yun; Zhao, Yue; Chen, Xi-Wen; Kong, Ling-Bin

2018-02-01

The porous carbon material is obtained via pyrolysis and activation of fructus cannabis’s shells, an easy-to-get biomass source, and is used as an active electrode material for supercapacitors. The obtained carbon exhibit a high specific surface area of 2389 m2 g-1. And the result of x-ray photoelectron spectroscopy (XPS) shows that the obtained porous carbon possess numerous oxygen groups, which can facilitate the wettability of the electrode. The prepared porous carbon also exhibit remarkable electrochemical properties, such as high specific capacitance of 357 F g-1 at a current density of 0.5 A g-1 in 6 mol L-1 aqueous KOH electrolyte, good rate capability of 77% capacitance retention as the current density increase from 0.5 A g-1 to 10 A g-1. In addition, it also presents a superior cycling stability of 100% capacitance retention after 10 000 cycles at the current density of 1 A g-1.

Semi-Interpenetrating Polymer Networks for Enhanced Supercapacitor Electrodes.

PubMed

Fong, Kara D; Wang, Tiesheng; Kim, Hyun-Kyung; Kumar, R Vasant; Smoukov, Stoyan K

2017-09-08

Conducting polymers show great promise as supercapacitor materials due to their high theoretical specific capacitance, low cost, toughness, and flexibility. Poor ion mobility, however, can render active material more than a few tens of nanometers from the surface inaccessible for charge storage, limiting performance. Here, we use semi-interpenetrating networks (sIPNs) of a pseudocapacitive polymer in an ionically conductive polymer matrix to decrease ion diffusion length scales and make virtually all of the active material accessible for charge storage. Our freestanding poly(3,4-ethylenedioxythiophene)/poly(ethylene oxide) (PEDOT/PEO) sIPN films yield simultaneous improvements in three crucial elements of supercapacitor performance: specific capacitance (182 F/g, a 70% increase over that of neat PEDOT), cycling stability (97.5% capacitance retention after 3000 cycles), and flexibility (the electrodes bend to a <200 μm radius of curvature without breaking). Our simple and controllable sIPN fabrication process presents a framework to develop a range of polymer-based interpenetrated materials for high-performance energy storage technologies.

Density Functional Theory Calculations of the Quantum Capacitance of Graphene Oxide as a Supercapacitor Electrode.

PubMed

Song, Ce; Wang, Jinyan; Meng, Zhaoliang; Hu, Fangyuan; Jian, Xigao

2018-03-31

Graphene oxide has become an attractive electrode-material candidate for supercapacitors thanks to its higher specific capacitance compared to graphene. The quantum capacitance makes relative contributions to the specific capacitance, which is considered as the major limitation of graphene electrodes, while the quantum capacitance of graphene oxide is rarely concerned. This study explores the quantum capacitance of graphene oxide, which bears epoxy and hydroxyl groups on its basal plane, by employing density functional theory (DFT) calculations. The results demonstrate that the total density of states near the Fermi level is significantly enhanced by introducing oxygen-containing groups, which is beneficial for the improvement of the quantum capacitance. Moreover, the quantum capacitances of the graphene oxide with different concentrations of these two oxygen-containing groups are compared, revealing that more epoxy and hydroxyl groups result in a higher quantum capacitance. Notably, the hydroxyl concentration has a considerable effect on the capacitive behavior. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ternary carbon composite films for supercapacitor applications

NASA Astrophysics Data System (ADS)

Tran, Minh-Hai; Jeong, Hae Kyung

2017-09-01

A simple, binder-free, method of making supercapacitor electrodes is introduced, based on modification of activated carbon with graphite oxide and carbon nanotubes. The three carbon precursors of different morphologies support each other to provide outstanding electrochemical performance, such as high capacitance and high energy density. The ternary carbon composite shows six times higher specific capacitance compared to that of activated carbon itself with high retention. The excellent electrochemical properties of the ternary composite attribute to the high surface area of 1933 m2 g-1 and low equivalent series resistance of 2 Ω, demonstrating that it improve the electrochemical performance for supercapacitor applications.

Organic memory device with self-assembly monolayered aptamer conjugated nanoparticles

NASA Astrophysics Data System (ADS)

Oh, Sewook; Kim, Minkeun; Kim, Yejin; Jung, Hunsang; Yoon, Tae-Sik; Choi, Young-Jin; Jung Kang, Chi; Moon, Myeong-Ju; Jeong, Yong-Yeon; Park, In-Kyu; Ho Lee, Hyun

2013-08-01

An organic memory structure using monolayered aptamer conjugated gold nanoparticles (Au NPs) as charge storage nodes was demonstrated. Metal-pentacene-insulator-semiconductor device was adopted for the non-volatile memory effect through self assembly monolayer of A10-aptamer conjugated Au NPs, which was formed on functionalized insulator surface with prostate-specific membrane antigen protein. The capacitance versus voltage (C-V) curves obtained for the monolayered Au NPs capacitor exhibited substantial flat-band voltage shift (ΔVFB) or memory window of 3.76 V under (+/-)7 V voltage sweep. The memory device format can be potentially expanded to a highly specific capacitive sensor for the aptamer-specific biomolecule detection.

Na/K-ATPase regulates bovine sperm capacitation through raft- and non-raft-mediated signaling mechanisms.

PubMed

Rajamanickam, Gayathri D; Kastelic, John P; Thundathil, Jacob C

2017-11-01

Highly dynamic lipid microdomains (rafts) in the sperm plasma membrane contain several signaling proteins that regulate sperm capacitation. Na/K-ATPase isoforms (testis-specific isoform ATP1A4 and ubiquitous isoform ATP1A1) are abundant in bovine sperm plasma membrane. We previously reported that incubation of bovine sperm with ouabain, a specific Na/K-ATPase ligand, induced tyrosine phosphorylation of several sperm proteins during capacitation. The objective of this study was to investigate the roles of lipid rafts and non-rafts in Na/K-ATPase enzyme activity and signaling during bovine sperm capacitation. Content of ATP1A4 and, to a lesser extent, ATP1A1 was increased in raft and non-raft fractions of capacitated sperm, although non-raft enzyme activities of both isoforms were higher than the corresponding activities in rafts from capacitated sperm. Yet, ATP1A4 was the predominant isoform responsible for total Na/K-ATPase activity in both rafts and non-rafts. A comparative increase in phosphorylation of signaling molecules was observed in both raft (CAV1) and non-raft (EGFR and ERK1/2) membrane fractions during capacitation. Although SRC was phosphorylated in both membrane fractions, the non-raft fraction possessed more of this activated form. We also inferred, by immunoprecipitation, that ATP1A4 interacted with CAV1 and EGFR in the raft fraction, whereas interactions of ATP1A4 with SRC, EGFR, and ERK1/2 occurred in the non-raft fraction of ouabain-capacitated sperm; conversely, ATP1A1 interacted only with CAV1 in both fractions of uncapacitated and capacitated sperm. In conclusion, both raft and non-raft cohorts of Na/K-ATPase isoforms contributed to phosphorylation of signaling molecules during bovine sperm capacitation. © 2017 Wiley Periodicals, Inc.

Design and construction of three-dimensional CuO/polyaniline/rGO ternary hierarchical architectures for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Zhu, Sheng; Wu, Mi; Ge, Mei-Hong; Zhang, Hui; Li, Shi-Kuo; Li, Chuan-Hao

2016-02-01

Rational design in terms of component and microstructure and fabrication of electrochemical electrodes are crucially important towards superior energy storage device. Herein, we report a novel CuO-PANI-rGO ternary hybrid electrode self-assembled by an in situ polymerization method combined with hydrothermal route for electrochemical capacitor. Well-defined CuO hierarchical architecture is synthesized by the spontaneous oxidization of Cu nanowire. PANI acts as not only binder for anchoring CuO architecture on rGO surface, but also charge transport channels, and high specific capacitance donor to the whole electrode matrix. The typical CuO-PANI-rGO ternary hybrid electrode can be reversibly cycled in a high voltage region up to 1.2 V. And it displays a maximum specific capacitance of 634.4 F g-1 and a high energy density of 126.8 Wh kg-1 with a power density of 114.2 kW kg-1 at a current density of 1.0 A g-1. Furthermore, the ternary hybrid electrode exhibits great cycle life with 97.4% specific capacitance retention after 10000 cycles. Those excellent performances are proposed to derive from the well-defined nanostructure, conductive porous microstructure and homogenously contact. This study might be important for designing the unique structure and component electrode for achieving high performance energy storage device.

Hierarchical porous carbon materials derived from petroleum pitch for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Abudu, Patiman; Wang, Luxiang; Xu, Mengjiao; Jia, Dianzeng; Wang, Xingchao; Jia, Lixia

2018-06-01

In this work, a honeycomb-like carbon material derived from petroleum pitch was synthesized by a simple one-step carbonization/activation method using silica nanospheres as the hard templates. The obtained hierarchical porous carbon materials (HPCs) with a large specific surface area and uniform macropore distribution provide abundant active sites and sufficient ion migration channels. When used as an electrode material for supercapacitors, the HPCs exhibit a high specific capacitance of 341.0 F g-1 at 1 A g-1, excellent rate capability with a capacitance retention of 55.6% at 50 A g-1 (189.5 F g-1), and outstanding cycling performance in the three-electrode system.

Nanoarchitectured Nb2O5 hollow, Nb2O5@carbon and NbO2@carbon Core-Shell Microspheres for Ultrahigh-Rate Intercalation Pseudocapacitors

NASA Astrophysics Data System (ADS)

Kong, Lingping; Zhang, Chuanfang; Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

2016-02-01

Li-ion intercalation materials with extremely high rate capability will blur the distinction between batteries and supercapacitors. We construct a series of nanoarchitectured intercalation materials including orthorhombic (o-) Nb2O5 hollow microspheres, o-Nb2O5@carbon core-shell microspheres and tetragonal (t-) NbO2@carbon core-shell microspheres, through a one-pot hydrothermal method with different post-treatments. These nanoarchitectured materials consist of small nanocrystals with highly exposed active surface, and all of them demonstrate good Li+ intercalation pseudocapacitive properties. In particular, o-Nb2O5 hollow microspheres can deliver the specific capacitance of 488.3 F g-1, and good rate performance of 126.7 F g-1 at 50 A g-1. The o-Nb2O5@carbon core-shell microspheres show enhanced specific capacitance of 502.2 F g-1 and much improved rate performance (213.4 F g-1 at 50 A g-1). Furthermore, we demonstrate for the first time, t-NbO2 exhibits much higher rate capability than o-Nb2O5. For discharging time as fast as 5.9 s (50 A g-1), it still exhibits a very high specific capacitance of 245.8 F g-1, which is 65.2% retention of the initial capacitance (377.0 F g-1 at 1 A g-1). The unprecedented rate capability is an intrinsic feature of t-NbO2, which may be due to the conductive lithiated compounds.

Nanoarchitectured Nb2O5 hollow, Nb2O5@carbon and NbO2@carbon Core-Shell Microspheres for Ultrahigh-Rate Intercalation Pseudocapacitors

PubMed Central

Kong, Lingping; Zhang, Chuanfang; Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

2016-01-01

Li-ion intercalation materials with extremely high rate capability will blur the distinction between batteries and supercapacitors. We construct a series of nanoarchitectured intercalation materials including orthorhombic (o-) Nb2O5 hollow microspheres, o-Nb2O5@carbon core-shell microspheres and tetragonal (t-) NbO2@carbon core-shell microspheres, through a one-pot hydrothermal method with different post-treatments. These nanoarchitectured materials consist of small nanocrystals with highly exposed active surface, and all of them demonstrate good Li+ intercalation pseudocapacitive properties. In particular, o-Nb2O5 hollow microspheres can deliver the specific capacitance of 488.3 F g−1, and good rate performance of 126.7 F g−1 at 50 A g−1. The o-Nb2O5@carbon core-shell microspheres show enhanced specific capacitance of 502.2 F g−1 and much improved rate performance (213.4 F g−1 at 50 A g−1). Furthermore, we demonstrate for the first time, t-NbO2 exhibits much higher rate capability than o-Nb2O5. For discharging time as fast as 5.9 s (50 A g−1), it still exhibits a very high specific capacitance of 245.8 F g−1, which is 65.2% retention of the initial capacitance (377.0 F g−1 at 1 A g−1). The unprecedented rate capability is an intrinsic feature of t-NbO2, which may be due to the conductive lithiated compounds. PMID:26880276

Porous carbon nanosheets from coal tar for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

He, Xiaojun; Ma, Hao; Wang, Jingxian; Xie, Yuanyang; Xiao, Nan; Qiu, Jieshan

2017-07-01

A hydroxide-template strategy coupled with in-situ chemical activation is reported for the first time to fabricate porous carbon nanosheets (PCNSs) from coal tar. The thin PCNSs feature abundant short pores accessible for fast ion transport and high specific surface area up to 3235 m2 g-1 for ion adsorption. As electrodes for supercapacitors, the PCNSs show a high capacitance of 296.2 F g-1 at 0.05 A g-1 in 6 M KOH electrolyte, an excellent rate performance with a capacitance of 220.7 F g-1 at 20 A g-1 and a superior cycle stability with over 97.2% capacitance retention after 11000 charge-discharge cycles at 3.5 A g-1. This work paves a new way for efficient fabrication of sheet-like carbon materials with tuned porous structure from polycyclic aromatic hydrocarbons for high performance supercapacitors.

High-Performance Supercapacitor Electrode Based on Cobalt Oxide-Manganese Dioxide-Nickel Oxide Ternary 1D Hybrid Nanotubes.

PubMed

Singh, Ashutosh K; Sarkar, Debasish; Karmakar, Keshab; Mandal, Kalyan; Khan, Gobinda Gopal

2016-08-17

We report a facile method to design Co3O4-MnO2-NiO ternary hybrid 1D nanotube arrays for their application as active material for high-performance supercapacitor electrodes. This as-prepared novel supercapacitor electrode can store charge as high as ∼2020 C/g (equivalent specific capacitance ∼2525 F/g) for a potential window of 0.8 V and has long cycle stability (nearly 80% specific capacitance retains after successive 5700 charge/discharge cycles), significantly high Coulombic efficiency, and fast response time (∼0.17s). The remarkable electrochemical performance of this unique electrode material is the outcome of its enormous reaction platform provided by its special nanostructure morphology and conglomeration of the electrochemical properties of three highly redox active materials in a single unit.

P-Doped NiCo2S4 nanotubes as battery-type electrodes for high-performance asymmetric supercapacitors.

PubMed

Lin, Jinghuang; Wang, Yiheng; Zheng, Xiaohang; Liang, Haoyan; Jia, Henan; Qi, Junlei; Cao, Jian; Tu, Jinchun; Fei, Weidong; Feng, Jicai

2018-06-19

NiCo2S4 is a promising electrode material for supercapacitors, due to its rich redox reactions and intrinsically high conductivity. Unfortunately, in most cases, NiCo2S4-based electrodes often suffer from low specific capacitance, low rate capability and fast capacitance fading. Herein, we have rationally designed P-doped NiCo2S4 nanotube arrays to improve the electrochemical performance through a phosphidation reaction. Characterization results demonstrate that the P element is successfully doped into NiCo2S4 nanotube arrays. Electrochemical results demonstrate that P-doped NiCo2S4 nanotube arrays exhibit better electrochemical performance than pristine NiCo2S4, e.g. higher specific capacitance (8.03 F cm-2 at 2 mA cm-2), good cycling stability (87.5% capacitance retention after 5000 cycles), and lower charge transfer resistance. More importantly, we also assemble an asymmetric supercapacitor using P-doped NiCo2S4 nanotube arrays and activated carbon on carbon cloth, which delivers a maximum energy density of 42.1 W h kg-1 at a power density of 750 W kg-1. These results demonstrate that the as-fabricated P-doped NiCo2S4 nanotube arrays on carbon cloth show great potential as a battery-type electrode for high-performance supercapacitors.

A facile approach to fabricate flexible all-solid-state supercapacitors based on MnFe2O4/graphene hybrids

NASA Astrophysics Data System (ADS)

Cai, Weihua; Lai, Ting; Dai, Wanlin; Ye, Jianshan

2014-06-01

A critical challenge for the construction of flexible electrochemical capacitors is the preparation of flexible electrodes with large specific capacitance and robust mechanical strength. Here, we demonstrate a facile approach to make high performance and flexible electrodes by dropping MnFe2O4/graphene hybrid inks onto flexible graphite sheets (as current collectors and substrates) and drying under an infrared lamp. MnFe2O4/graphene hybrid inks are synthesized by immobilizing the MnFe2O4 microspheres on the graphene nanosheets via a simple solvothermal route. Electrochemical studies show that MnFe2O4/graphene exhibits a high capacitance of 300 F g-1 at a current density of 0.3 A g-1. In addition, the excellent electrochemical performance of a supercapacitor consisting of a sandwich structure of two pieces of MnFe2O4/graphene hybrids modified electrodes separated by polyvinyl alcohol (PVA)-H2SO4 gel electrolyte is further explored. Our studies reveal that the flexible supercapacitor device with 227 μm thickness can achieve a maximum specific capacitance of 120 F g-1 at a current density of 0.1 A g-1 and excellent cycle performance retaining 105% capacitance after 5000 cycles. This research may offer a method for the fabrication of lightweight, stable, flexible and high performance energy storage devices.

High Volumetric Energy Density Asymmetric Supercapacitors Based on Well-Balanced Graphene and Graphene-MnO2 Electrodes with Densely Stacked Architectures.

PubMed

Sheng, Lizhi; Jiang, Lili; Wei, Tong; Fan, Zhuangjun

2016-10-01

The well-matched electrochemical parameters of positive and negative electrodes, such as specific capacitance, rate performance, and cycling stability, are important for obtaining high-performance asymmetric supercapacitors. Herein, a facile and cost-effective strategy is demonstrated for the fabrication of 3D densely stacked graphene (DSG) and graphene-MnO 2 (G-MnO 2 ) architectures as the electrode materials for asymmetric supercapacitors (ASCs) by using MnO 2 -intercalated graphite oxide (GO-MnO 2 ) as the precursor. DSG has a stacked graphene structure with continuous ion transport network in-between the sheets, resulting in a high volumetric capacitance of 366 F cm -3 , almost 2.5 times than that of reduced graphene oxide, as well as long cycle life (93% capacitance retention after 10 000 cycles). More importantly, almost similar electrochemical properties, such as specific capacitance, rate performance, and cycling stability, are obtained for DSG as the negative electrode and G-MnO 2 as the positive electrode. As a result, the assembled ASC delivers both ultrahigh gravimetric and volumetric energy densities of 62.4 Wh kg -1 and 54.4 Wh L -1 (based on total volume of two electrodes) in 1 m Na 2 SO 4 aqueous electrolyte, respectively, much higher than most of previously reported ASCs in aqueous electrolytes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrafine MnO2 Nanowire Arrays Grown on Carbon Fibers for High-Performance Supercapacitors

NASA Astrophysics Data System (ADS)

Hu, Jiyu; Qian, Feng; Song, Guosheng; Li, Wenyao; Wang, Linlin

2016-10-01

Large-area ultrafine MnO2 nanowire arrays (NWA) directly grew on a carbon fiber (CF, used as a substrate) by a simple electrochemical method, forming three-dimensional (3D) hierarchical heterostructures of a CF@MnO2 NWA composite. As an electrode for supercapacitors, the CF@MnO2 NWA composite exhibits excellent electrochemical performances including high specific capacitance (321.3 F g-1 at 1000 mA g-1) and good rate capability. Further, the overall capacitance retention is 99.7 % capacitance after 3000 cycles. These outstanding electrochemical performances attribute to a large number of transport channels for the penetration of electrolyte and the transportation of ions and electrons of electrodes. The as-prepared CF@MnO2 NWA composite may be a promising electrode material for high-performance supercapacitors.

Ultrafine MnO2 Nanowire Arrays Grown on Carbon Fibers for High-Performance Supercapacitors.

PubMed

Hu, Jiyu; Qian, Feng; Song, Guosheng; Li, Wenyao; Wang, Linlin

2016-12-01

Large-area ultrafine MnO 2 nanowire arrays (NWA) directly grew on a carbon fiber (CF, used as a substrate) by a simple electrochemical method, forming three-dimensional (3D) hierarchical heterostructures of a CF@MnO 2 NWA composite. As an electrode for supercapacitors, the CF@MnO 2 NWA composite exhibits excellent electrochemical performances including high specific capacitance (321.3 F g -1 at 1000 mA g -1 ) and good rate capability. Further, the overall capacitance retention is ~99.7 % capacitance after 3000 cycles. These outstanding electrochemical performances attribute to a large number of transport channels for the penetration of electrolyte and the transportation of ions and electrons of electrodes. The as-prepared CF@MnO 2 NWA composite may be a promising electrode material for high-performance supercapacitors.

Ultrahigh-performance pseudocapacitor based on phase-controlled synthesis of MoS2 nanosheets decorated Ni3S2 hybrid structure through annealing treatment

NASA Astrophysics Data System (ADS)

Huang, Long; Hou, Huijie; Liu, Bingchuan; Zeinu, Kemal; Zhu, Xiaolei; Yuan, Xiqing; He, Xiulin; Wu, Longsheng; Hu, Jingping; Yang, Jiakuan

2017-12-01

In this work, a hierarchical Ni3S2@MoS2 hybrid structure was synthesized by an effective strategy with a combined hydrothermal route and subsequent annealing treatment. When tested as supercapacitor electrodes, the Ni3S2@MoS2 composites exhibited high specific capacitance of 1418.5 F g-1 at 0.5 A g-1, which also showed a good capacitance retention of 75.8% at 5 A g-1 after 1250 cycles. The Ni3S2@MoS2 composites demonstrated 1.9 fold higher specific capacitance compared to the amorphous shell counterpart (NixSy@MoS2). Furthermore, the assembled asymmetric supercapacitor (Ni3S2@MoS2//rGO) also demonstrated a capacitance of 61 F g-1 at 0.5 A g-1, with energy and power densities of 21.7 Wh kg-1 at 400 W kg-1 and 12 Wh kg-1 at 2400 W kg-1 under an operating window of 1.6 V. The asymmetric supercapacitor also showed a favorable cycle stability with 72% capacity retention over 4000 cycles at 10 A g-1. The improved electrochemical performance is attributed to the synergetic effect of the large accessible surface area and optimal contacts between the MoS2 and the electrolyte, as well as high capacitance of the metallic Ni3S2 core.

Enhanced Capacitance of Hybrid Layered Graphene/Nickel Nanocomposite for Supercapacitors

PubMed Central

Mohd Zaid, Norsaadatul Akmal; Idris, Nurul Hayati

2016-01-01

In this work, Ni nanoparticles were directly decorated on graphene (G) nanosheets via mechanical ball milling. Based on transmission electron microscopy observations, the Ni nanoparticles were well dispersed and attached to the G nanosheet without any agglomerations. Electrochemical results showed that the capacitance of a G/Ni nanocomposite was 275 F g−1 at a current density of 2 A g−1, which is higher than the capacitance of bare G (145 F g−1) and bare Ni (3 F g−1). The G/Ni electrode also showed superior performance at a high current density, exhibiting a capacitance of 190 F g−1 at a current density of 5 A g−1 and a capacitance of 144 F g−1 at a current density of 10 A g−1. The equivalent series resistance for G/Ni nanocomposites also decreased. The enhanced performance of this hybrid supercapacitor is best described by the synergistic effect, i.e. dual charge-storage mechanism, which is demonstrated by electrical double layer and pseudocapacitance materials. Moreover, a high specific surface area and electrical conductivity of the materials enhanced the capacitance. These results indicate that the G/Ni nanocomposite is a potential supercapacitor. PMID:27553290

Three-dimensional reduced graphene oxide/polyaniline nanocomposite film prepared by diffusion driven layer-by-layer assembly for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Hong, Xiaodong; Zhang, Binbin; Murphy, Elizabeth; Zou, Jianli; Kim, Franklin

2017-03-01

As a simple and versatile method, diffusion driven Layer-by-Layer assembly (dd-LbL) is developed to assemble graphene oxide (GO) into three-dimensional (3D) structure. The assembled GO macrostructure can be reduced through a hydrothermal treatment and used as a high volumetric capacitance electrode in supercapacitors. In this report we use rGO framework created from dd-LbL as a scaffold for in situ polymerization of aniline within the pores of the framework to form rGO/polyaniline (rGO/PANI) composite. The rGO/PANI composite affords a robust and porous structure, which facilitates electrolyte diffusion and exhibits excellent electrochemical performance as binder-free electrodes in a sandwich-configuration supercapacitor. Combining electric double layer capacitance and pseudo-capacitance, rGO/PANI electrodes exhibit a specific capacitance of 438.8 F g-1 at discharge rate of 5 mA (mass of electrodes were 10.0 mg, 0.5 A g-1) in 1 mol L-1 H2SO4 electrolyte; furthermore, the generated PANI nanoparticles in rGO template achieve a higher capacitance of 763 F g-1. The rGO/PANI composite electrodes also show an improved recyclability, 76.5% of capacitance retains after recycled 2000 times.

High voltage electrochemical double layer capacitors using conductive carbons as additives

NASA Astrophysics Data System (ADS)

Michael, M. S.; Prabaharan, S. R. S.

We describe here an interesting approach towards electrochemical capacitors (ECCs) using graphite materials (as being used as conductive additives in rechargeable lithium-ion battery cathodes) in a Li + containing organic electrolyte. The important result is that we achieved a voltage window of >4 V, which is rather large, compared to the standard window of 2.5 V for ordinary electric double layer capacitors (DLCs). The capacitor performance was evaluated by cyclic voltammetry (CV) and galvanostatic charge/discharge techniques. From charge-discharge studies of the symmetrical device (for instance, SFG6 carbon electrode), a specific capacitance of up to 14.5 F/g was obtained at 16 mA/cm 2 current rate and at a low current rate (3 mA/cm 2), a higher value was obtained (63 F/g). The specific capacitance decreased about 25% after 1000 cycles compared to the initial discharge process. The performances of these graphites are discussed in the light of both double layer capacitance (DLC) and pseudocapacitance (battery-like behavior). The high capacitance obtained was not only derived from the current-transient capacitive behavior but is also attributed to pseudocapacitance associated with some kind of faradaic reaction, which could probably occur due to Li + intercalation/deintercalation reactions into graphitic layers of the carbons used. The ac impedance (electrochemical impedances spectroscopy, EIS) measurements were also carried out to evaluate the capacitor parameters such as equivalent series resistance (ESR) and frequency dependent capacitance ( Cfreq). Cyclic voltammetry measurements were also performed to evaluate the cycling behavior of the carbon electrodes and the non-rectangular shaped voltammograms revealed the non-zero time constant [ τ( RC)≠0] confirming that the current contains a transient as well as steady-state components.

Free-standing 3D polyaniline-CNT/Ni-fiber hybrid electrodes for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Li, Yuan; Fang, Yuzhu; Liu, Hong; Wu, Xiaoming; Lu, Yong

2012-04-01

Free-standing 3D macroscopic polyaniline (PANi)-carbon nanotube (CNT)-nickel fiber hybrids have been developed, and they deliver high specific capacitance (725 F g-1 at 0.5 A g-1) and high energy density at high rates (~22 W h kg-1 at 2000 W kg-1, based on total electrode mass) with good cyclability.Free-standing 3D macroscopic polyaniline (PANi)-carbon nanotube (CNT)-nickel fiber hybrids have been developed, and they deliver high specific capacitance (725 F g-1 at 0.5 A g-1) and high energy density at high rates (~22 W h kg-1 at 2000 W kg-1, based on total electrode mass) with good cyclability. Electronic supplementary information (ESI) available: Experimental details on preparation, characterization, and electrochemical testing; Fig. S1-S8, Schemes S1 and S2. See DOI: 10.1039/c2nr30252g

Three-dimensional polypyrrole-derived carbon nanotube framework for dye adsorption and electrochemical supercapacitor

NASA Astrophysics Data System (ADS)

Xin, Shengchang; Yang, Na; Gao, Fei; Zhao, Jing; Li, Liang; Teng, Chao

2017-08-01

Three-dimensional carbon nanotube frameworks have been prepared via pyrolysis of polypyrrole nanotube aerogels that are synthesized by the simultaneous self-degraded template synthesis and hydrogel assembly followed by freeze-drying. The microstructure and composition of the materials are investigated by thermal gravimetric analysis, Raman spectrum, X-ray photoelectron spectroscopy, transmission electron microscopy, and specific surface analyzer. The results confirm the formation of three-dimensional carbon nanotube frameworks with low density, high mechanical properties, and high specific surface area. Compared with PPy aerogel precursor, the as-prepared three-dimensional carbon nanotube frameworks exhibit outstanding adsorption capacity towards organic dyes. Moreover, electrochemical tests show that the products possess high specific capacitance, good rate capability and excellent cycling performance with no capacitance loss over 1000 cycles. These characteristics collectively indicate the potential of three-dimensional polypyrrole-derived carbon nanotube framework as a promising macroscopic device for the applications in environmental and energy storages.

Synthesis and capacitance properties of N-doped porous carbon/NiO nanosheet composites using coal-based polyaniline as carbon and nitrogen source

NASA Astrophysics Data System (ADS)

Wang, Xiaoqin; Li, Qiaoqin; Zhang, Yong; Yang, Yufei; Cao, Zhi; Xiong, Shanxin

2018-06-01

A novel synthesis approach of N-doped porous carbon (NPC)/NiO composites possessing some honeycomb-shaped nanoporous carbon and plentiful NiO nanosheets is exploited. First NPC/Ni composites are achieved with NPC yield of 52.9% through a catalytic pyrolysis method, using coal-based polyaniline particles prepared by an in-situ polymerization method as a carbon and nitrogen source, and nickel particles as a catalyst, respectively. Next NPC/NiO composites are achieved unexpectedly with plentiful NiO nanosheets and N content of 1.00 wt% after a liquid oxidation process. In NPC/NiO composites, porous carbon mainly presents in the amorphous state, while the incorporated nitrogen mainly presents in the form of pyrrolic N (92.9 at.%) and oxidized N (7.1 at.%). Plentiful NiO nanosheets are embedded in the pores or on the NPC surface. 33.3 at.% Ni2O3 components exist in the surface of NiO nanosheets. NPC/NiO composites possess not only rich micropores, but also significant mesopores and nanoscale macropores. The BET specific surface area, BET average pore width and BJH adsorption average pore diameter are 627.5 m2/g, 2.0 nm and 5.1 nm, respectively. NPC/NiO composites demonstrate a high specific capacitance of 404.1 F/g at 1 A/g, and a good cycling stability maintaining high specific capacitance of 212.4 F/g (84.3% of the initial capacitance) at 5 A/g after 5000 cycles of charge and discharge, attributed to some honeycomb-shaped nanopores of carbon and large specific surface area of NiO nanosheets, and the synergistic effects between electric double-layer capacitance of NPC and pseudocapacitance of NiO. This study may provide a novel approach for the value-added applications of low-rank coal.

Supercapacitive properties of hybrid films of manganese dioxide and polyaniline based on active carbon in organic electrolyte

NASA Astrophysics Data System (ADS)

Zou, Wu-yuan; Wang, Wei; He, Ben-lin; Sun, Ming-liang; Yin, Yan-sheng

This is the first report about supercapacitive performance of hybrid film of manganese dioxide (MnO 2) and polyaniline (PANI) in an organic electrolyte (1.0 M LiClO 4 in acetonitrile). In this work, a high surface area and conductivity of active carbon (AC) electrode is used as a substrate for PANI/MnO 2 film electro-codeposition. The redox properties of the coated PANI/MnO 2 thin film exhibit ideal capacitive behaviour in 1 M LiClO 4/AN. The specific capacitance (SC) of PANI/MnO 2 hybrid film is as high as 1292 F g -1 and maintains about 82% of the initial capacitance after 1500 cycles at a current density of 4.0 mA cm -2, and the coulombic efficiency (η) is higher than 95%. An asymmetric capacitor has been developed with the PANI/MnO 2/AC positive and pure AC negative electrodes, which is able to deliver a specific energy as high as 61 Wh kg -1 at a specific power of 172 W kg -1 in the range of 0-2.0 V. These results indicate that the organic electrolyte is a promising candidate for PANI/MnO 2 material application in supercapacitors.

Inhibiting Sperm Pyruvate Dehydrogenase Complex and Its E3 Subunit, Dihydrolipoamide Dehydrogenase Affects Fertilization in Syrian Hamsters

PubMed Central

Sailasree, Purnima; Singh, Durgesh K.; Kameshwari, Duvurri B.; Shivaji, Sisinthy

2014-01-01

Background/Aims The importance of sperm capacitation for mammalian fertilization has been confirmed in the present study via sperm metabolism. Involvement of the metabolic enzymes pyruvate dehydrogenase complex (PDHc) and its E3 subunit, dihydrolipoamide dehydrogenase (DLD) in hamster in vitro fertilization (IVF) via in vitro sperm capacitation is being proposed through regulation of sperm intracellular lactate, pH and calcium. Methodology and Principal Findings Capacitated hamster spermatozoa were allowed to fertilize hamster oocytes in vitro which were then assessed for fertilization, microscopically. PDHc/DLD was inhibited by the use of the specific DLD-inhibitor, MICA (5-methoxyindole-2-carboxylic acid). Oocytes fertilized with MICA-treated (MT) [and thus PDHc/DLD-inhibited] spermatozoa showed defective fertilization where 2nd polar body release and pronuclei formation were not observed. Defective fertilization was attributable to capacitation failure owing to high lactate and low intracellular pH and calcium in MT-spermatozoa during capacitation. Moreover, this defect could be overcome by alkalinizing spermatozoa, before fertilization. Increasing intracellular calcium in spermatozoa pre-IVF and in defectively-fertilized oocytes, post-fertilization rescued the arrest seen, suggesting the role of intracellular calcium from either of the gametes in fertilization. Parallel experiments carried out with control spermatozoa capacitated in medium with low extracellular pH or high lactate substantiated the necessity of optimal sperm intracellular lactate levels, intracellular pH and calcium during sperm capacitation, for proper fertilization. Conclusions This study confirms the importance of pyruvate/lactate metabolism in capacitating spermatozoa for successful fertilization, besides revealing for the first time the importance of sperm PDHc/ DLD in fertilization, via the modulation of sperm intracellular lactate, pH and calcium during capacitation. In addition, the observations made in the IVF studies in hamsters suggest that capacitation failures could be a plausible cause of unsuccessful fertilization encountered during human assisted reproductive technologies, like IVF and ICSI. Our studies indicate a role of sperm capacitation in the post-penetration events during fertilization. PMID:24852961

PolyHIPE Derived Freestanding 3D Carbon Foam for Cobalt Hydroxide Nanorods Based High Performance Supercapacitor

PubMed Central

Patil, Umakant M.; Ghorpade, Ravindra V.; Nam, Min Sik; Nalawade, Archana C.; Lee, Sangrae; Han, Haksoo; Jun, Seong Chan

2016-01-01

The current paper describes enhanced electrochemical capacitive performance of chemically grown Cobalt hydroxide (Co(OH)2) nanorods (NRs) decorated porous three dimensional graphitic carbon foam (Co(OH)2/3D GCF) as a supercapacitor electrode. Freestanding 3D porous GCF is prepared by carbonizing, high internal phase emulsion (HIPE) polymerized styrene and divinylbenzene. The PolyHIPE was sulfonated and carbonized at temperature up to 850 °C to obtain graphitic 3D carbon foam with high surface area (389 m2 g−1) having open voids (14 μm) interconnected by windows (4 μm) in monolithic form. Moreover, entangled Co(OH)2 NRs are anchored on 3D GCF electrodes by using a facile chemical bath deposition (CBD) method. The wide porous structure with high specific surface area (520 m2 g−1) access offered by the interconnected 3D GCF along with Co(OH)2 NRs morphology, displays ultrahigh specific capacitance, specific energy and power. The Co(OH)2/3D GCF electrode exhibits maximum specific capacitance about ~1235 F g−1 at ~1 A g−1 charge-discharge current density, in 1 M aqueous KOH solution. These results endorse potential applicability of Co(OH)2/3D GCF electrode in supercapacitors and signifies that, the porous GCF is a proficient 3D freestanding framework for loading pseudocapacitive nanostructured materials. PMID:27762284

Capacitive Detection of Low-Enthalpy, Higher-Order Phase Transitions in Synthetic and Natural Composition Lipid Membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, Graham J.; Heberle, Frederick A.; Seinfeld, Jason S.

In-plane lipid organization and phase separation in natural membranes play key roles in regulating many cellular processes. Highly cooperative, first-order phase transitions in model membranes consisting of few lipid components are well understood and readily detectable via calorimetry, densitometry, and fluorescence. However, far less is known about natural membranes containing numerous lipid species and high concentrations of cholesterol, for which thermotropic transitions are undetectable by the above-mentioned techniques. We demonstrate that membrane capacitance is highly sensitive to low-enthalpy thermotropic transitions taking place in complex lipid membranes. Specifically, we measured the electrical capacitance as a function of temperature for droplet interfacemore » bilayer model membranes of increasing compositional complexity, namely, (a) a single lipid species, (b) domain-forming ternary mixtures, and (c) natural brain total lipid extract (bTLE). We observed that, for single-species lipid bilayers and some ternary compositions, capacitance exhibited an abrupt, temperature-dependent change that coincided with the transition detected by other techniques. In addition, capacitance measurements revealed transitions in mixed-lipid membranes that were not detected by the other techniques. Most notably, capacitance measurements of bTLE bilayers indicated a transition at ~38 °C not seen with any other method. Likewise, capacitance measurements detected transitions in some well-studied ternary mixtures that, while known to yield coexisting lipid phases, are not detected with calorimetry or densitometry. These results indicate that capacitance is exquisitely sensitive to low-enthalpy membrane transitions because of its sensitivity to changes in bilayer thickness that occur when lipids and excess solvent undergo subtle rearrangements near a phase transition. Our findings also suggest that heterogeneity confers stability to natural membranes that function near transition temperatures by preventing unwanted defects and macroscopic demixing associated with high-enthalpy transitions commonly found in simpler mixtures.« less

Capacitive Detection of Low-Enthalpy, Higher-Order Phase Transitions in Synthetic and Natural Composition Lipid Membranes

DOE PAGES

Taylor, Graham J.; Heberle, Frederick A.; Seinfeld, Jason S.; ...

2017-08-15

In-plane lipid organization and phase separation in natural membranes play key roles in regulating many cellular processes. Highly cooperative, first-order phase transitions in model membranes consisting of few lipid components are well understood and readily detectable via calorimetry, densitometry, and fluorescence. However, far less is known about natural membranes containing numerous lipid species and high concentrations of cholesterol, for which thermotropic transitions are undetectable by the above-mentioned techniques. We demonstrate that membrane capacitance is highly sensitive to low-enthalpy thermotropic transitions taking place in complex lipid membranes. Specifically, we measured the electrical capacitance as a function of temperature for droplet interfacemore » bilayer model membranes of increasing compositional complexity, namely, (a) a single lipid species, (b) domain-forming ternary mixtures, and (c) natural brain total lipid extract (bTLE). We observed that, for single-species lipid bilayers and some ternary compositions, capacitance exhibited an abrupt, temperature-dependent change that coincided with the transition detected by other techniques. In addition, capacitance measurements revealed transitions in mixed-lipid membranes that were not detected by the other techniques. Most notably, capacitance measurements of bTLE bilayers indicated a transition at ~38 °C not seen with any other method. Likewise, capacitance measurements detected transitions in some well-studied ternary mixtures that, while known to yield coexisting lipid phases, are not detected with calorimetry or densitometry. These results indicate that capacitance is exquisitely sensitive to low-enthalpy membrane transitions because of its sensitivity to changes in bilayer thickness that occur when lipids and excess solvent undergo subtle rearrangements near a phase transition. Our findings also suggest that heterogeneity confers stability to natural membranes that function near transition temperatures by preventing unwanted defects and macroscopic demixing associated with high-enthalpy transitions commonly found in simpler mixtures.« less

2D nickel oxide nanosheets with highly porous structure for high performance capacitive energy storage

NASA Astrophysics Data System (ADS)

Li, Zijiong; Zhang, Weiyang; Liu, Yanyue; Guo, Jinjin; Yang, Baocheng

2018-01-01

Developing advanced electrochemical electrode materials with excellent performance is critical to their future energy storage devices. Herein, we design and synthesize two-dimensional (2D) porous structure nickel oxide (NiO) nanosheets via a facile and scalable hydrothermal approach, and further heating. The effects of heating time on the electrochemical performances are investigated. The results indicate that the maximum specific capacitance is achieved for NiO nanosheets when heating temperature and time are 300 °C and 3 h, respectively (namely NiO-3). The as-prepared NiO-3 nanosheet are grown uniform on the skeleton of reduced graphene oxide (rGO). The optimum NiO/rGO displays a reversible discharge capacity of 781.7 F g-1 at 1 A g-1, and shows an ultra-long life-span with over 94% capacitance retention after 4000 cycles. The enhanced electrochemical properties for NiO/rGO can be ascribed to a collaborative effect between NiO and rGO, which possess high capacitance storage ability and excellent conductivity, respectively.

Polypyrrole electrodes doped with sulfanilic acid azochromotrop for electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Chen, S.; Zhitomirsky, I.

2013-12-01

In this work we demonstrate the feasibility of deposition of polypyrrole (PPy) films by electropolymerization on stainless steel substrates and fabrication of PPy powders by chemical polymerization using sulfanilic acid azochromotrop (SPADNS) as a new anionic dopant. The problem of low adhesion of PPy films to stainless steel substrates is addressed by the use of SPADNS, which exhibits chelating properties, promoting film formation. The use of fine particles, prepared by the chemical polymerization method, allows impregnation of Ni foams and fabrication of porous electrodes with high materials loading for electrochemical supercapacitors (ES). PPy films and Ni foam based PPy electrodes show capacitive behaviour in Na2SO4 electrolyte. The electron microscopy studies, impedance spectroscopy data and analysis of the SPADNS structure provide an insight into the factors, controlling capacitive behaviour. The Ni foam based electrodes offer advantages of improved capacitive behaviour at high materials loadings and good cycling stability. The area normalized and volume normalized specific capacitances are as high as 5.43 F cm-2 and 93.6 F cm-3, respectively, for materials loading of 35.4 mg cm-2. The capacitance retention of Ni foam based electrodes is 91.5% after 1000 cycles. The Ni foam based PPy electrodes are promising for application in ES.

Two-Dimensional, Porous Nickel-Cobalt Sulfide for High-Performance Asymmetric Supercapacitors.

PubMed

Li, Xiaoming; Li, Qiguang; Wu, Ye; Rui, Muchen; Zeng, Haibo

2015-09-02

High specific surface area, high electrical conductivity, and abundant channels have been recognized to favor pseudocapacitors, but their realization at the same time is still a great challenge. Here, we report on nickel-cobalt sulfide nanosheets (NSs) with both ultrathin thickness and nanoscale pores for supercapacitors. The porous Ni-Co sulfide NSs were facilely synthesized through micelle-confined growth and subsequent sulfuration. The NSs are as thin as several nanometers and have a large number of pores with a mean size of ∼7 nm, resulting in ultrahigh atom ratio at surface with unique chemical and electronic structure. Therefore, fast diffusion of ions, facile transportation of electrons and high activity make great synergistic contributions to the surface-dependent reversible redox reactions. In the resulted supercapacitors, a specific capacitance of 1304 F g(-1) is achieved at a current density of 2 A g(-1) with excellent rate capability that 85.6% of the original capacitance is remained at 20 A g(-1). The effects of crystallinity and self-doping are optimized so that 93.5% of the original capacitance is obtained after 6000 cycles at a high current density of 8 A g(-1). Finally, asymmetric supercapacitors with a high energy density of 41.4 Wh/kg are achieved at a power density of 414 W/kg.

Titanium nitride films for micro-supercapacitors: Effect of surface chemistry and film morphology on the capacitance

NASA Astrophysics Data System (ADS)

Achour, Amine; Porto, Raul Lucio; Soussou, Mohamed-Akram; Islam, Mohammad; Boujtita, Mohammed; Aissa, Kaltouma Ait; Le Brizoual, Laurent; Djouadi, Abdou; Brousse, Thierry

2015-12-01

Electrochemical capacitors (EC) in the form of packed films can be integrated in various electronic devices as power source. A fabrication process of EC electrodes, which is compatible with micro-fabrication, should be addressed for practical applications. Here, we show that titanium nitride films with controlled porosity can be deposited on flat silicon substrates by reactive DC-sputtering for use as high performance micro-supercapacitor electrodes. A superior volumetric capacitance as high as 146.4 F cm-3, with an outstanding cycling stability over 20,000 cycles, was measured in mild neutral electrolyte of potassium sulfate. The specific capacitance of the films as well as their capacitance retentions were found to depend on thickness, porosity and surface chemistry of electrodes. The one step process used to fabricate these TiN electrodes and the wide use of this material in the field of semiconductor technology make it promising for miniaturized energy storage systems.

A Triblock Copolymer Design Leads to Robust Hybrid Hydrogels for High-Performance Flexible Supercapacitors.

PubMed

Zhang, Guangzhao; Chen, Yunhua; Deng, Yonghong; Wang, Chaoyang

2017-10-18

We report here an intriguing hybrid conductive hydrogel as electrode for high-performance flexible supercapacitor. The key is using a rationally designed water-soluble ABA triblock copolymer (termed as IAOAI) containing a central poly(ethylene oxide) block (A) and terminal poly(acrylamide) (PAAm) block with aniline moieties randomly incorporated (B), which was synthesized by reversible additional fragment transfer polymerization. The subsequent copolymerization of aniline monomers with the terminated aniline moieties on the IAOAI polymer generates a three-dimensional cross-linking hybrid network. The hybrid hydrogel electrode demonstrates robust mechanical flexibility, remarkable electrochemical capacitance (919 F/g), and cyclic stability (90% capacitance retention after 1000 cycles). Moreover, the flexible supercapacitor based on this hybrid hydrogel electrode presents a large specific capacitance (187 F/g), superior to most reported conductive hydrogel-based supercapacitors. With the demonstrated additional favorable cyclic stability and excellent capacitive and rate performance, this hybrid hydrogel-based supercapacitor holds great promise for flexible energy-storage device.

Fabricate BC/Fe3O4@PPy 3D nanofiber film as flexible electrode for supercapacitor application

NASA Astrophysics Data System (ADS)

Lv, Xvdan; Li, Guohui; Pang, Zengyuan; Li, Dawei; Lei, Luo; Lv, Pengfei; Mushtaq, Muhammad; Wei, Qufu

2018-05-01

For flexible film supercapacitor, high areal capacitance is a main evaluating indicator. In this paper, bacterial cellulose (BC) with special three-dimensional structure was used as the natural flexible base material. Fe3O4 nanoparticles with average diameter of 20 nm were synthesized on the surface of BC fibers. The conductive path polypyrrole (PPy) was introduced as shell of BC/Fe3O4 fibers to further improve the pseudo capacitance in 1 mol/L H2SO4 solution. Besides, the BC/Fe3O4@PPy was used for supercapacitor application in acid electrolyte, and delivered higher areal capacitance compared to other Fe3O4 composites in previous reports. The obtained BC/Fe3O4@PPy film showed excellent mechanical strength (tensile strength reached 11 MPa), high areal specific capacitance (5.4 F cm-2 at active mass of 8.4 mg cm-2), and long cycle life (1.95 F cm-2 over 3500 cycles).

Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method

PubMed Central

Ning, Xuewen; Wang, Xixin; Yu, Xiaofei; Zhao, Jianling; Wang, Mingli; Li, Haoran; Yang, Yang

2016-01-01

Mn-doped TiO2 micro/nanostructure porous film was prepared by anodizing a Ti-Mn alloy. The film annealed at 300 °C yields the highest areal capacitance of 1451.3 mF/cm2 at a current density of 3 mA/cm2 when used as a high-performance supercapacitor electrode. Areal capacitance retention is 63.7% when the current density increases from 3 to 20 mA/cm2, and the capacitance retention is 88.1% after 5,000 cycles. The superior areal capacitance of the porous film is derived from the brush-like metal substrate, which could greatly increase the contact area, improve the charge transport ability at the oxide layer/metal substrate interface, and thereby significantly enhance the electrochemical activities toward high performance energy storage. Additionally, the effects of manganese content and specific surface area of the porous film on the supercapacitive performance were also investigated in this work. PMID:26940546

Rational Synthesis of Branched CoMoO4@CoNiO2 Core/Shell Nanowire Arrays for All-Solid-State Supercapacitors with Improved Performance.

PubMed

Ai, Yuanfei; Geng, Xuewen; Lou, Zheng; Wang, Zhiming M; Shen, Guozhen

2015-11-04

Effectively composite materials with optimized structures exhibited promising potential in continuing improving the electrochemical performances of supercapacitors in the past few years. Here, we proposed a rational design of branched CoMoO4@CoNiO2 core/shell nanowire arrays on Ni foam by two steps of hydrothermal processing. Owing to the high activity of the scaffold-like CoMoO4 nanowires and the well-defined CoNiO2 nanoneedles, the three-dimensional (3D) electrode architectures achieved remarkable electrochemical performances with high areal specific capacitance (5.31 F/cm(2) at 5 mA/cm(2)) and superior cycling stability(159% of the original specific capacitance, i.e., 95.7% of the maximum retained after 5000 cycles at 30 mA/cm(2)). The all-solid-state asymmetric supercapacitors composed of such electrode and activated carbon (AC) exhibited an areal specific capacitance of 1.54 F/cm(2) at 10 mA/cm(2) and a rate capability (59.75 Wh/kg at a 1464 W/kg) comparable with Li-ion batteries. It also showed an excellent cycling stability with no capacitance attenuation after 50000 cycles at 100 mA/cm(2). After rapid charging (1 s), such supercapacitors in series could lighten a red LED for a long time and drive a mini motor effectively, demonstrating advances in energy storage, scalable integrated applications, and promising commercial potential.

A doped activated carbon prepared from polyaniline for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Li, Limin; Liu, Enhui; Li, Jian; Yang, Yanjing; Shen, Haijie; Huang, Zhengzheng; Xiang, Xiaoxia; Li, Wen

A novel doped activated carbon has been prepared from H 2SO 4-doped polyaniline which is prepared by the oxypolymerization of aniline. The morphology, surface chemical composition and surface area of the carbon have been investigated by scanning electron microscope, X-ray photoelectron spectroscopy and Brunaner-Emmett-Teller measurement, respectively. Electrochemical properties of the doped activated carbon have been studied by cyclic voltammograms, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 6 mol l -1 KOH. The specific capacitance of the carbon is as high as 235 F g -1, the specific capacitance hardly decreases at a high current density 11 A g -1 after 10,000 cycles, which indicates that the carbon possesses excellent cycle durability and may be a promising candidate for supercapacitors.

Microwave-assisted rapid synthesis of birnessite-type MnO{sub 2} nanoparticles for high performance supercapacitor applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xiong; Miao, Wang; Li, Chen

Highlights: • Birnessite-type MnO{sub 2} nanoparticles were prepared by the microwave-assisted reflux. • The microwave reaction duration was only 5 min. • A specific capacitance of 329 F g{sup −1} was obtained for birnessite-type MnO{sub 2}. - Abstract: Birnessite-type MnO{sub 2} nanoparticles have been successfully synthesized by the microwave-assisted reflux as short as 5 min. The microstructure and morphology of the products were characterized by X-ray diffraction, N{sub 2} adsorption–desorption isotherms, scanning electron microscopy, transmission electron microscopy. The electrochemical properties of the as-prepared MnO{sub 2} as an electrode material for supercapacitor were investigated by cyclic voltammetry and galvanostatic charge-discharge measurementsmore » in 1 M Na{sub 2}SO{sub 4} electrolyte, and a high specific capacitance of 329 F g{sup −1} was achieved at a current density of 0.2 A g{sup −1}. The specific capacitance retention was 92% after 1000 cycles at 2 A g{sup −1}, suggesting that it is a promising electrode material for supercapacitors.« less

High-Performance Flexible Solid-State Carbon Cloth Supercapacitors Based on Highly Processible N-Graphene Doped Polyacrylic Acid/Polyaniline Composites

PubMed Central

Wang, Yongguang; Tang, Shaochun; Vongehr, Sascha; Ali Syed, Junaid; Wang, Xiangyu; Meng, Xiangkang

2016-01-01

Improving the solubility of conductive polymers to facilitate processing usually decreases their conductivity, and they suffer from poor cycling stability due to swelling-shrinking during charging cycles. We circumvent these problems with a novel preparation method for nitrogen-doped graphene (NG) enhanced polyacrylic acid/polyaniline (NG-PAA/PANI) composites, ensuring excellent processibility for scalable production. The content of PANI is maximized under the constraint of still allowing defect-free coatings on filaments of carbon cloth (CC). The NG content is then adjusted to optimize specific capacitance. The optimal CC electrodes have 32 wt.% PANI and 1.3 wt.% NG, thus achieving a high capacitance of 521 F/g at 0.5 F/g. A symmetric supercapacitor made from 20 wt.% PANI CC electrodes has more than four times the capacitance (68 F/g at 1 A/g) of previously reported flexible capacitors based on PANI-carbon nanotube composites, and it retains the full capacitance under large bending angles. The capacitor exhibits high energy and power densities (5.8 Wh/kg at 1.1 kW/kg), a superior rate capability (still 81% of the 1 A/g capacitance at 10 A/g), and long-term electrochemical stability (83.2% retention after 2000 cycles). PMID:26883179

Free-standing and porous hierarchical nanoarchitectures constructed with cobalt cobaltite nanowalls for supercapacitors with high specific capacitances

NASA Astrophysics Data System (ADS)

Xiao, Yuanhua; Zhang, Aiqin; Liu, Shaojun; Zhao, Jihong; Fang, Shaoming; Jia, Dianzeng; Li, Feng

2012-12-01

Free-standing and porous hierarchical nanoarchitectures constructed with cobalt cobaltite (Co3O4) nanowalls have been successfully synthesized in large scale by calcining three dimensional (3D) hierarchical nanostructures consisting of single crystalline cobalt carbonate hydroxide hydrate - Co(CO3)0.5(OH)·0.11H2O nanowalls prepared with a solvothermal method. The step-by-step decomposition of the precursor can generate porous Co3O4 nanowalls with BET surface area of 88.34 m2 g-1. The as-prepared Co3O4 nanoarchitectures show superior specific capacitance to the most Co3O4 supercapacitor electrode materials to date. After continuously cycled for 1000 times of charge-discharge at 4 A g-1, the supercapacitors can retain ca 92.3% of their original specific capacitances. The excellent performances of the devices can be attributed to the porous and hierarchical 3D nanostructure of the materials.

Nitrogen-doped biomass/polymer composite porous carbons for high performance supercapacitor

NASA Astrophysics Data System (ADS)

Shu, Yu; Maruyama, Jun; Iwasaki, Satoshi; Maruyama, Shohei; Shen, Yehua; Uyama, Hiroshi

2017-10-01

Nitrogen-doped porous monolithic carbon (NDPMC) is obtained from biomass-derived activated carbon/polyacrylonitrile composite for the first time via a template-free thermally induced phase separation (TIPS) approach followed by KOH activation. The electrochemical results indicate that NDPMC possesses ultrahigh specific capacitance of 442 F g-1 at 1 A g-1, excellent rate capability with 81% retention rate from 1 to 100 A g-1 and outstanding cycling stability with 98% capacitance retention at 20 A g-1 after 5000 cycles. Furthermore, the evaluation of NDPMC on the practical symmetrical system also exhibits desired electrochemical performances. The novel composite carbon displays remarkable capacitance properties and the feasible, low-cost synthetic route demonstrates great potential for large-scale production of high-performance electrode materials for supercapacitors.

Charge storage in β-FeSi2 nanoparticles

NASA Astrophysics Data System (ADS)

Theis, Jens; Bywalez, Robert; Küpper, Sebastian; Lorke, Axel; Wiggers, Hartmut

2015-02-01

We report on the observation of a surprisingly high specific capacitance of β-FeSi2 nanoparticle layers. Lateral, interdigitated capacitor structures were fabricated on thermally grown silicon dioxide and covered with β-FeSi2 particles by drop or spin casting. The β-FeSi2-nanoparticles, with crystallite sizes in the range of 10-30 nm, were fabricated by gas phase synthesis in a hot wall reactor. Compared to the bare electrodes, the nanoparticle-coated samples exhibit a 3-4 orders of magnitude increased capacitance. Time-resolved current voltage measurements show that for short times (seconds to minutes), the material is capable of storing up to 1 As/g at voltages of around 1 V. The devices are robust and exhibit long-term stability under ambient conditions. The specific capacitance is highest for a saturated relative humidity, while for a relative humidity below 40% the capacitance is almost indistinguishable from a nanoparticle-free reference sample. The devices work without the need of a fluid phase, the charge storing material is abundant and cost effective, and the sample design is easy to fabricate.

Hydrothermal solid-gas route to TiO2 nanoparticles/nanotube arrays for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Fan, Haowen; Zhang, He; Luo, Xiaolei; Liao, Maoying; Zhu, Xufei; Ma, Jing; Song, Ye

2017-07-01

Although TiO2 nanotube arrays (TNTAs) have shown great promise as supercapacitor materials, their specific capacitances are still not comparable with some typical materials. Here, TiO2 nanoparticles (NPs)/TNTAs hybrid structure has been derived from the anodized TNTAs by a facile hydrothermal solid-gas method (HSGM), which can avoid cracking or curling of the TNTAs from Ti substrate. The obtained NPs/TNTAs hybrid structure can exhibit a ∼4.90 times increase in surface area and a ∼5.49 times increase in areal specific capacitance compared to the TNTAs without HSGM treatment. Besides, the argon-atmosphere annealing can offer improved areal capacitance and cycling stability relative to the air-atmosphere annealing. The hydrothermal vapor pressure is a key factor for controlling microscopic morphologies of TNTAs, the morphology transformations of TNTAs during the HSGM treatment can be accelerated under enhanced vapor pressures. The highest areal capacitance of HSGM-treated TNTAs is up to 76.12 mF cm-2 at 0.5 mA cm-2, well above that of any TiO2 materials reported to date.

Highly Flexible and Conductive Cellulose-Mediated PEDOT:PSS/MWCNT Composite Films for Supercapacitor Electrodes.

PubMed

Zhao, Dawei; Zhang, Qi; Chen, Wenshuai; Yi, Xin; Liu, Shouxin; Wang, Qingwen; Liu, Yixing; Li, Jian; Li, Xianfeng; Yu, Haipeng

2017-04-19

Recent improvements in flexible electronics have increased the need to develop flexible and lightweight power sources. However, current flexible electrodes are limited by low capacitance, poor mechanical properties, and lack of cycling stability. In this article, we describe an ionic liquid-processed supramolecular assembly of cellulose and 3,4-ethylenedioxythiophene for the formation of a flexible and conductive cellulose/poly(3,4-ethylenedioxythiophene) PEDOT:poly(styrene sulfonate) (PSS) composite matrix. On this base, multiwalled carbon nanotubes (MWCNTs) were incorporated into the matrix to fabricate an MWCNT-reinforced cellulose/PEDOT:PSS film (MCPP), which exhibited favorable flexibility and conductivity. The MCPP-based electrode displayed comprehensively excellent electrochemical properties, such as a low resistance of 0.45 Ω, a high specific capacitance of 485 F g -1 at 1 A g -1 , and good cycling stability, with a capacity retention of 95% after 2000 cycles at 2 A g -1 . An MCPP-based symmetric solid-state supercapacitor with Ni foam as the current collector and PVA/KOH gel as the electrolyte exhibited a specific capacitance of 380 F g -1 at 0.25 A g -1 and achieved a maximum energy density of 13.2 Wh kg -1 (0.25 A g -1 ) with a power density of 0.126 kW kg -1 or an energy density of 4.86 Wh kg -1 at 10 A g -1 , corresponding to a high power density of 4.99 kW kg -1 . Another kind of MCPP-based solid-state supercapacitor without the Ni foam showed excellent flexibility and a high volumetric capacitance of 50.4 F cm -3 at 0.05 A cm -3 . Both the electrodes and the supercapacitors were environmentally stable and could be operated under remarkable deformation or high temperature without damage to their structural integrity or a significant decrease in capacitive performance. Overall, this work provides a strategy for the fabrication of flexible and conductive energy-storage films with ionic liquid-processed cellulose as a medium.

Improved capacitance characteristics of electrospun ACFs by pore size control and vanadium catalyst.

PubMed

Im, Ji Sun; Woo, Sang-Wook; Jung, Min-Jung; Lee, Young-Seak

2008-11-01

Nano-sized carbon fibers were prepared by using electrospinning, and their electrochemical properties were investigated as a possible electrode material for use as an electric double-layer capacitor (EDLC). To improve the electrode capacitance of EDLC, we implemented a three-step optimization. First, metal catalyst was introduced into the carbon fibers due to the excellent conductivity of metal. Vanadium pentoxide was used because it could be converted to vanadium for improved conductivity as the pore structure develops during the carbonization step. Vanadium catalyst was well dispersed in the carbon fibers, improving the capacitance of the electrode. Second, pore-size development was manipulated to obtain small mesopore sizes ranging from 2 to 5 nm. Through chemical activation, carbon fibers with controlled pore sizes were prepared with a high specific surface and pore volume, and their pore structure was investigated by using a BET apparatus. Finally, polyacrylonitrile was used as a carbon precursor to enrich for nitrogen content in the final product because nitrogen is known to improve electrode capacitance. Ultimately, the electrospun activated carbon fibers containing vanadium show improved functionality in charge/discharge, cyclic voltammetry, and specific capacitance compared with other samples because of an optimal combination of vanadium, nitrogen, and fixed pore structures.

Hierarchical activated mesoporous phenolic-resin-based carbons for supercapacitors.

PubMed

Wang, Zhao; Zhou, Min; Chen, Hao; Jiang, Jingui; Guan, Shiyou

2014-10-01

A series of hierarchical activated mesoporous carbons (AMCs) were prepared by the activation of highly ordered, body-centered cubic mesoporous phenolic-resin-based carbon with KOH. The effect of the KOH/carbon-weight ratio on the textural properties and capacitive performance of the AMCs was investigated in detail. An AMC prepared with a KOH/carbon-weight ratio of 6:1 possessed the largest specific surface area (1118 m(2) g(-1)), with retention of the ordered mesoporous structure, and exhibited the highest specific capacitance of 260 F g(-1) at a current density of 0.1 A g(-1) in 1 M H2 SO4 aqueous electrolyte. This material also showed excellent rate capability (163 F g(-1) retained at 20 A g(-1)) and good long-term electrochemical stability. This superior capacitive performance could be attributed to a large specific surface area and an optimized micro-mesopore structure, which not only increased the effective specific surface area for charge storage but also provided a favorable pathway for efficient ion transport. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facile Synthesis of Carbon Nanosphere/NiCo2O4 Core-shell Sub-microspheres for High Performance Supercapacitor

PubMed Central

Li, Delong; Gong, Youning; Zhang, Yupeng; Luo, Chengzhi; Li, Weiping; Fu, Qiang; Pan, Chunxu

2015-01-01

This paper introduced a process to prepare the carbon nanosphere (CNS)/NiCo2O4 core-shell sub-microspheres. That is: 1) CNSs were firstly prepared via a simple hydrothermal method; 2) a layer of NiCo2O4 precursor was coated on the CNS surface; 3) finally the composite was annealed at 350 °C for 2 hours in the air, and the CNS/NiCo2O4 core-shell sub-microspheres were obtained. This core-shell sub-microsphere was prepared with a simple, economical and environmental-friendly hydrothermal method, and was suitable for large-scale production, which expects a promising electrode candidate for high performance energy storage applications. Electrochemical experiments revealed that the composite exhibited remarkable electrochemical performances with high capacitance and desirable cycle life at high rates, such as: 1) the maximum specific capacitance was up to 1420 F/g at 1 A/g; 2) about 98.5% of the capacitance retained after 3000 charge-discharge cycles; 3) the capacitance retention was about 72% as the current density increase from 1 A/g to 10 A/g. PMID:26245982

Nanostructure selenium compounds as pseudocapacitive electrodes for high-performance asymmetric supercapacitor.

PubMed

Ma, Guofu; Hua, Fengting; Sun, Kanjun; Fenga, Enke; Peng, Hui; Zhang, Zhiguo; Lei, Ziqiang

2018-01-01

The electrochemical performance of an energy conversion and storage device like the supercapacitor mainly depends on the microstructure and morphology of the electrodes. In this paper, to improve the capacitance performance of the supercapacitor, the all-pseudocapacitive electrodes of lamella-like Bi 18 SeO 29 /BiSe as the negative electrode and flower-like Co 0.85 Se nanosheets as the positive electrode are synthesized by using a facile low-temperature one-step hydrothermal method. The microstructures and morphology of the electrode materials are carefully characterized, and the capacitance performances are also tested. The Bi 18 SeO 29 /BiSe and Co 0.85 Se have high specific capacitance (471.3 F g -1 and 255 F g -1 at 0.5 A g -1 ), high conductivity, outstanding cycling stability, as well as good rate capability. The assembled asymmetric supercapacitor completely based on the pseudocapacitive electrodes exhibits outstanding cycling stability (about 93% capacitance retention after 5000 cycles). Moreover, the devices exhibit high energy density of 24.2 Wh kg -1 at a power density of 871.2 W kg -1 in the voltage window of 0-1.6 V with 2 M KOH solution.

Metal-Organic Coordination Polymer to Prepare Density Controllable and High Nitrogen-Doped Content Carbon/Graphene for High Performance Supercapacitors.

PubMed

Luo, Jinwei; Zhong, Wenbin; Zou, Yubo; Xiong, Changlun; Yang, Wantai

2017-01-11

Design and preparation of carbon-based electrode material with high nitrogen-doping ratio and appropriate density attract much interest for supercapacitors in practical application. Herein, three porous carbon/graphene (NCG Cu , NCG Fe , and NCG Zn ) with high doping ratio of nitrogen have been prepared via directly pyrolysis of graphene oxide (GO)/metal-organic coordination polymer (MOCP) composites, which were formed by reacting 4,4'-bipyridine (BPD) with CuCl 2 , FeCl 3 , and ZnCl 2 , respectively. As-prepared NCG Cu , NCG Fe and NCG Zn showed high nitrogen doping ratio of 10.68, 12.99, and 11.21 at. %; and high density of 1.52, 0.84, and 1.15 g cm -3 , respectively. When as-prepared samples were used as supercapacitor electrodes, NCG Cu , NCG Fe and NCG Zn exhibited high gravimetric specific capacitances of 369, 298.5, 309.5 F g -1 , corresponding to high volumetric specific capacitances of 560.9, 250.7, 355.9 F cm -3 at a current density of 0.5 A g -1 , as well as good cycling stability, nearly 100% of the capacitance retained after 1000 cycles even at a large current density of 10 A g -1 . It is expected that the provided novel strategy can be used to develop electrode materials in high performance energy conversion/storage devices.

Porous carbon nanotube/graphene composites for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Li, Jing; Tang, Jie; Yuan, Jinshi; Zhang, Kun; Yu, Xiaoliang; Sun, Yige; Zhang, Han; Qin, Lu-Chang

2018-02-01

Carbon nanotubes (CNTs) are an effective spacer to prevent the re-stacking of graphene layers. However, the aggregation of CNTs always reduces the specific surface area of resulting CNT/graphene composites. Meanwhile, different pores always have different contributions to the specific capacitance. In this study, CNT/graphene composites with different porous structures are synthesized by co-reduction of oxidized CNTs and graphene oxide with different mixing ratios. With an optimized CNT content of 20%, the CNT/graphene composite shows 206 F g-1 in 1-ethyl-3-methylimidazolium tetrafluoroborate electrolyte. It is found that pores larger than twice the size of electrolyte ions can make greater contributions to the specific capacitance.

High-performance supercapacitors based on vertically aligned carbon nanotubes and nonaqueous electrolytes

NASA Astrophysics Data System (ADS)

Kim, Byungwoo; Chung, Haegeun; Kim, Woong

2012-04-01

We demonstrate the high performance of supercapacitors fabricated with vertically aligned carbon nanotubes and nonaqueous electrolytes such as ionic liquids and conventional organic electrolytes. Specific capacitance, maximum power and energy density of the supercapacitor measured in ionic liquid were ˜75 F g-1, ˜987 kW kg-1 and ˜27 W h kg-1, respectively. The high power performance was consistently indicated by a fast relaxation time constant of 0.2 s. In addition, electrochemical oxidation of the carbon nanotubes improved the specific capacitance (˜158 F g-1) and energy density (˜53 W h kg-1). Both high power and energy density could be attributed to the fast ion transport realized by the alignment of carbon nanotubes and the wide operational voltage defined by the ionic liquid. The demonstrated carbon-nanotube- and nonaqueous-electrolyte-based supercapacitors show great potential for the development of high-performance energy storage devices.

New energy storage option: toward ZnCo2O4 nanorods/nickel foam architectures for high-performance supercapacitors.

PubMed

Liu, Bin; Liu, Boyang; Wang, Qiufan; Wang, Xianfu; Xiang, Qingyi; Chen, Di; Shen, Guozhen

2013-10-23

Hierarchical ZnCo2O4/nickel foam architectures were first fabricated from a simple scalable solution approach, exhibiting outstanding electrochemical performance in supercapacitors with high specific capacitance (∼1400 F g(-1) at 1 A g(-1)), excellent rate capability (72.5% capacity retention at 20 A g(-1)), and good cycling stability (only 3% loss after 1000 cycles at 6 A g(-1)). All-solid-state supercapacitors were also fabricated by assembling two pieces of the ZnCo2O4-based electrodes, showing superior performance in terms of high specific capacitance and long cycling stability. Our work confirms that the as-prepared architectures can not only be applied in high energy density fields, but also be used in high power density applications, such as electric vehicles, flexible electronics, and energy storage devices.

High-performance supercapacitors based on vertically aligned carbon nanotubes and nonaqueous electrolytes.

PubMed

Kim, Byungwoo; Chung, Haegeun; Kim, Woong

2012-04-20

We demonstrate the high performance of supercapacitors fabricated with vertically aligned carbon nanotubes and nonaqueous electrolytes such as ionic liquids and conventional organic electrolytes. Specific capacitance, maximum power and energy density of the supercapacitor measured in ionic liquid were ~75 F g(-1), ~987 kW kg(-1) and ~27 W h kg(-1), respectively. The high power performance was consistently indicated by a fast relaxation time constant of 0.2 s. In addition, electrochemical oxidation of the carbon nanotubes improved the specific capacitance (~158 F g(-1)) and energy density (~53 W h kg(-1)). Both high power and energy density could be attributed to the fast ion transport realized by the alignment of carbon nanotubes and the wide operational voltage defined by the ionic liquid. The demonstrated carbon-nanotube- and nonaqueous-electrolyte-based supercapacitors show great potential for the development of high-performance energy storage devices. © 2012 IOP Publishing Ltd

Hierarchical mesoporous nickel cobaltite nanoneedle/carbon cloth arrays as superior flexible electrodes for supercapacitors

PubMed Central

2014-01-01

Hierarchical mesoporous NiCo2O4 nanoneedle arrays on carbon cloth have been fabricated by a simple hydrothermal approach combined with a post-annealing treatment. Such unique array nanoarchitectures exhibit remarkable electrochemical performance with high capacitance and desirable cycle life at high rates. When evaluated as an electrode material for supercapacitors, the NiCo2O4 nanoneedle arrays supported on carbon cloth was able to deliver high specific capacitance of 660 F g-1 at current densities of 2 A g-1 in 2 M KOH aqueous solution. In addition, the composite electrode shows excellent mechanical behavior and long-term cyclic stability (91.8% capacitance retention after 3,000 cycles). The fabrication method presented here is facile, cost-effective, and scalable, which may open a new pathway for real device applications. PMID:24661431

Hierarchical Mesoporous Zinc-Nickel-Cobalt Ternary Oxide Nanowire Arrays on Nickel Foam as High-Performance Electrodes for Supercapacitors.

PubMed

Wu, Chun; Cai, Junjie; Zhang, Qiaobao; Zhou, Xiang; Zhu, Ying; Shen, Pei Kang; Zhang, Kaili

2015-12-09

Nickel foam supported hierarchical mesoporous Zn-Ni-Co ternary oxide (ZNCO) nanowire arrays are synthesized by a simple two-step approach including a hydrothermal method and subsequent calcination process and directly utilized for supercapacitive investigation for the first time. The nickel foam supported hierarchical mesoporous ZNCO nanowire arrays possess an ultrahigh specific capacitance value of 2481.8 F g(-1) at 1 A g(-1) and excellent rate capability of about 91.9% capacitance retention at 5 A g(-1). More importantly, an asymmetric supercapacitor with a high energy density (35.6 Wh kg(-1)) and remarkable cycle stability performance (94% capacitance retention over 3000 cycles) is assembled successfully by employing the ZNCO electrode as positive electrode and activated carbon as negative electrode. The remarkable electrochemical behaviors demonstrate that the nickel foam supported hierarchical mesoporous ZNCO nanowire array electrodes are highly desirable for application as advanced supercapacitor electrodes.

Highly deformation-tolerant carbon nanotube sponges as supercapacitor electrodes.

PubMed

Li, Peixu; Kong, Chuiyan; Shang, Yuanyuan; Shi, Enzheng; Yu, Yuntao; Qian, Weizhong; Wei, Fei; Wei, Jinquan; Wang, Kunlin; Zhu, Hongwei; Cao, Anyuan; Wu, Dehai

2013-09-21

Developing flexible and deformable supercapacitor electrodes based on porous materials is of high interest in energy related fields. Here, we show that carbon nanotube sponges, consisting of highly porous conductive networks, can serve as compressible and deformation-tolerant supercapacitor electrodes in aqueous or organic electrolytes. In aqueous electrolytes, the sponges maintain a similar specific capacitance (>90% of the original value) under a predefined compressive strain of 50% (corresponding to a volume reduction of 50%), and retain more than 70% of the original capacitance under 80% strain while the volume normalized capacitance increases by 3-fold. The sponge electrode maintains a stable performance after 1000 large strain compression cycles. A coin-shaped cell assembled with these sponges shows excellent stability over 15,000 charging cycles with negligible degradation after 500 cycles. Our results indicate that carbon nanotube sponges have the potential to fabricate deformable supercapacitor electrodes with stable performance.

Predicting ion specific capacitances of supercapacitors due to quantum ionic interactions.

PubMed

Parsons, Drew F

2014-08-01

A new theoretical framework is now available to help explain ion specific (Hofmeister) effects. All measurements in physical chemistry show ion specificity, inexplicable by classical electrostatic theories. These ignore ionic dispersion forces that change ionic adsorption. We explored ion specificity in supercapacitors using a modified Poisson-Boltzmann approach that includes ionic dispersion energies. We have applied ab initio quantum chemical methods to determine required ion sizes and ion polarisabilities. Our model represents graphite electrodes through their optical dielectric spectra. The electrolyte was 1.2 M Li salt in propylene carbonate, using the common battery anions, PF6(-), BF4(-) and ClO4(-). We also investigated the perhalate series with BrO4(-) and IO4(-). The capacitance C=dσ/dψ was calculated from the predicted electrode surface charge σ of each electrode with potential ψ between electrodes. Compared to the purely electrostatic calculation, the capacitance of a positively charged graphite electrode was enhanced by more than 15%, with PF6(-) showing >50% increase in capacitance. IO4(-) provided minimal enhancement. The enhancement is due to adsorption of both anions and cations, driven by ionic dispersion forces. The Hofmeister series in the single-electrode capacitance was PF6(-)>BF4(-)>ClO4(-)>BrO4(-)>IO4(-) . When the graphite electrode was negatively charged, the perhalates provided almost no enhancement of capacitance, while PF6(-) and BF4(-) decreased capacitance by about 15%. Due to the asymmetric impact of nonelectrostatic ion interactions, the capacitances of positive and negative electrodes are not equal. The capacitance of a supercapacitor should therefore be reported as two values rather than one, similar to the matrix of mutual capacitances used in multielectrode devices. Copyright © 2014 Elsevier Inc. All rights reserved.

High-performance supercapacitor electrode from cellulose-derived, inter-bonded carbon nanofibers

NASA Astrophysics Data System (ADS)

Cai, Jie; Niu, Haitao; Wang, Hongxia; Shao, Hao; Fang, Jian; He, Jingren; Xiong, Hanguo; Ma, Chengjie; Lin, Tong

2016-08-01

Carbon nanofibers with inter-bonded fibrous structure show high supercapacitor performance when being used as electrode materials. Their preparation is highly desirable from cellulose through a pyrolysis technique, because cellulose is an abundant, low cost natural material and its carbonization does not emit toxic substance. However, interconnected carbon nanofibers prepared from electrospun cellulose nanofibers and their capacitive behaviors have not been reported in the research literature. Here we report a facile one-step strategy to prepare inter-bonded carbon nanofibers from partially hydrolyzed cellulose acetate nanofibers, for making high-performance supercapacitors as electrode materials. The inter-fiber connection shows considerable improvement in electrode electrochemical performances. The supercapacitor electrode has a specific capacitance of ∼241.4 F g-1 at 1 A g-1 current density. It maintains high cycling stability (negligible 0.1% capacitance reduction after 10,000 cycles) with a maximum power density of ∼84.1 kW kg-1. They may find applications in the development of efficient supercapacitor electrodes for energy storage applications.

Versatile NiO/mesoporous carbon nanodisks: controlled synthesis from hexagon shaped heterobimetallic metal-organic frameworks.

PubMed

Zeng, Dehong; Yang, Ying; Yang, Feng; Guo, Fangmin; Yang, Senjie; Liu, Baijun; Hao, Shijie; Ren, Yang

2017-08-24

Hexagonal NiO/mesoporous carbon nanodisks (NiO/MCN) are facilely and controllably synthesized via constructing nickel-zinc trimesic acid heterobimetallic metal-organic framework (HMOF) disks before pyrolysis at 910 °C. Tailoring the Ni/(Zn + Ni) feed ratio and the reaction time during the HMOF synthesis creates a well-defined hexagonal carbon nanodisk with properly populated NiO nanocrystals while maintaining high porosity and conductivity. Such an elaborately fabricated NiO/MCN is highly stable, and exhibits the largest specific capacitance of 261 F g -1 and the highest specific activity factor of 1.93 s -1 g -1 of any composite nanodisk during the capacitive test and 4-nitrophenol reduction, respectively.

Enhancing pseudocapacitive kinetics of nanostructured MnO2 through anchoring onto biomass-derived porous carbon

NASA Astrophysics Data System (ADS)

Chen, Qiongyu; Chen, Jizhang; Zhou, Yuyang; Song, Chao; Tian, Qinghua; Xu, Junling; Wong, Ching-Ping

2018-05-01

The rational construction of heterostructured electrode materials that deliver superior performances to their individual counterparts offers an attractive strategy for supercapacitors. Herein, we anchor low-crystalline nanostructured MnO2 onto soybean stalk-derived carbon matrix through chemical activation and subsequent hydrothermal reaction. The highly porous and conductive matrix can effectively enhance pseudocapacitive kinetics of nanostructured MnO2. Therefore, the obtained nanocomposite exhibits high specific capacitance (384.9 F g-1 at a current density of 0.5 A g-1), great rate capability (185.0 F g-1 at 20 A g-1), and superior cyclability (90.7% capacitance retention after 5000 cycles). Using this nanocomposite as the positive electrode material, an asymmetric supercapacitor (ASC) is assembled, and achieves high specific energy of 34.2 Wh kg-1 and high specific power of 9.58 kW kg-1. The results of this study demonstrate great potential of combining biomass-derived porous carbon with metal oxides.

A high-performance flexible fibre-shaped electrochemical capacitor based on electrochemically reduced graphene oxide.

PubMed

Li, Yingru; Sheng, Kaixuan; Yuan, Wenjing; Shi, Gaoquan

2013-01-11

A fibre-shaped solid electrochemical capacitor based on electrochemically reduced graphene oxide has been fabricated, exhibiting high specific capacitance and rate capability, long cycling life and attractive flexibility.

In vivo skin imaging for hydration and micro relief-measurement.

PubMed

Kardosova, Z; Hegyi, V

2013-01-01

We present the results of our work with device used for measurement of skin capacitance before and after application of moisturizing creams and results of experiment performed on cellulose filter papers soaked with different solvents. The measurements were performed by a device built on capacitance sensor, which provides an investigator with a capacitance image of the skin. The capacitance values are coded in a range of 256 gray levels then the skin hydration can be characterized using parameters derived from gray level histogram by specific software. The images obtained by device allow a highly precise observation of skin topography. Measuring of skin capacitance brings new, objective, reliable information about topographical, physical and chemical parameters of the skin. The study shows that there is a good correlation between the average grayscale values and skin hydration. In future works we need to complete more comparison studies, interpret the average grayscale values to skin hydration levels and use it for follow-up of dynamics of skin micro-relief and hydration changes (Fig. 6, Ref. 15).

Bendable solid-state supercapacitors with Au nanoparticle-embedded graphene hydrogel films

PubMed Central

Yang, Kyungwhan; Cho, Kyoungah; Yoon, Dae Sung; Kim, Sangsig

2017-01-01

In this study, we fabricate bendable solid-state supercapacitors with Au nanoparticle (NP)-embedded graphene hydrogel (GH) electrodes and investigate the influence of the Au NP embedment on the internal resistance and capacitive performance. Embedding the Au NPs into the GH electrodes results in a decrease of the internal resistance from 35 to 21 Ω, and a threefold reduction of the IR drop at a current density of 5 A/g when compared with GH electrodes without Au NPs. The Au NP-embedded GH supercapacitors (NP-GH SCs) exhibit excellent capacitive performances, with large specific capacitance (135 F/g) and high energy density (15.2 W·h/kg). Moreover, the NP-GH SCs exhibit comparable areal capacitance (168 mF/cm2) and operate under tensile/compressive bending. PMID:28074865

Soft and wrinkled carbon membranes derived from petals for flexible supercapacitors

PubMed Central

Yu, Xiuxiu; Wang, Ying; Li, Li; Li, Hongbian; Shang, Yuanyuan

2017-01-01

Biomass materials are promising precursors for the production of carbonaceous materials due to their abundance, low cost and renewability. Here, a freestanding wrinkled carbon membrane (WCM) electrode material for flexible supercapacitors (SCs) was obtained from flower petal. The carbon membrane was fabricated by a simple thermal pyrolysis process and further activated by heating the sample in air. As a binder and current collector-free electrode, the activated wrinkled carbon membrane (AWCM) exhibited a high specific capacitance of 332.7 F/g and excellent cycling performance with 92.3% capacitance retention over 10000 cycles. Moreover, a flexible all-solid supercapacitor with AWCM electrode was fabricated and showed a maximum specific capacitance of 154 F/g and great bending stability. The development of this flower petal based carbon membrane provides a promising cost-effective and environmental benign electrode material for flexible energy storage. PMID:28361914

Fabrication of 3D polypyrrole microstructures and their utilization as electrodes in supercapacitors

NASA Astrophysics Data System (ADS)

Ho, Vinh; Zhou, Cheng; Kulinsky, Lawrence; Madou, Marc

2013-12-01

We present a novel fabrication method for constructing three-dimensional (3D) conducting microstructures based on the controlled-growth of electrodeposited polypyrrole (PPy) within a lithographically patterned photoresist layer. PPy thin films, post arrays, suspended planes supported by post arrays and multi-layered PPy structures were fabricated. The performance of supercapacitors based on 3D PPy electrodes doped with dodecylbenzene sulfonate (DBS-) and perchlorate (ClO4-) anions was studied using cyclic voltammetry and galvanostatic charge/discharge tests. The highest specific capacitance obtained from the multi-layered PPy(ClO4) electrodes was 401 ± 18 mF cm-2, which is roughly twice as high as the highest specific capacitance of PPy-based supercapacitor reported thus far. The increase in capacitance is the result of higher surface area per unit footprint achieved through the fabrication of multi-layered 3D electrodes.

Surfactant free nickel sulphide nanoparticles for high capacitance supercapacitors

NASA Astrophysics Data System (ADS)

Nandhini, S.; Muralidharan, G.

2018-04-01

The surfactant free nickel sulphide nanoparticles were synthesized via facile hydrothermal method towards supercapacitor applications. The formation of crystalline spherical nanoparticles was confirmed through structural and morphological studies. Electrochemical behaviour of the electrode was analyzed using cyclic voltammetry (CV), galvanostatic charge-discharge studies (GCD) and electrochemical impedance spectroscopy (EIS). The CV studies imply that specific capacitance of the electrode arises from a combination of surface adsorption and Faradic reaction. The NiS electrode delivered a specific capacitance of about 529 F g-1 at a current density of 2 A g-1 (GCD measurements). A profitable charge transfer resistance of 0.5 Ω was obtained from EIS. The 100 % of capacity retention even after 2000 repeated charge-discharge cycles could be observed in 2 M KOH electrolyte at a much larger rate of 30 A g-1. The experimental results suggest that nickel sulphide is a potential candidate for supercapacitor applications.

Percoll gradient-centrifuged capacitated mouse sperm have increased fertilizing ability and higher contents of sulfogalactosylglycerolipid and docosahexaenoic acid-containing phosphatidylcholine compared to washed capacitated mouse sperm.

PubMed

Furimsky, Anna; Vuong, Ngoc; Xu, Hongbin; Kumarathasan, Premkumari; Xu, Min; Weerachatyanukul, Wattana; Bou Khalil, Maroun; Kates, Morris; Tanphaichitr, Nongnuj

2005-03-01

Although Percoll gradient centrifugation has been used routinely to prepare motile human sperm, its use in preparing motile mouse sperm has been limited. Here, we showed that Percoll gradient-centrifuged (PGC) capacitated mouse sperm had markedly higher fertilizing ability (sperm-zona pellucida [ZP] binding and in vitro fertilization) than washed capacitated mouse sperm. We also showed that the lipid profiles of PGC capacitated sperm and washed capacitated sperm differed significantly. The PGC sperm had much lower contents of cholesterol and phospholipids. This resulted in relative enrichment of male germ cell-specific sulfogalactosylglycerolipid (SGG), a ZP-binding ligand, in PGC capacitated sperm, and this would explain, in part, their increased ZP-binding ability compared with that of washed capacitated sperm. Analyses of phospholipid fatty acyl chains revealed that PGC capacitated sperm were enriched in phosphatidylcholine (PC) molecular species containing highly unsaturated fatty acids (HUFAs), with docosahexaenoic acid (DHA; C22: 6n-3) being the predominant HUFA (42% of total hydrocarbon chains of PC). In contrast, the level of PC-HUFAs comprising arachidonic acid (20:4n-6), docosapentaenoic acid (C22:5n-6), and DHA in washed capacitated sperm was only 27%. Having the highest unsaturation degree among all HUFAs in PC, DHA would enhance membrane fluidity to the uppermost. Therefore, membranes of PGC capacitated sperm would undergo fertilization-related fusion events at higher rates than washed capacitated sperm. These results suggested that PGC mouse sperm should be used in fertilization experiments and that SGG and DHA should be considered to be important biomarkers for sperm fertilizing ability.

Amorphous V-O-C composite nanofibers electrospun from solution precursors as binder- and conductive additive-free electrodes for supercapacitors with outstanding performance

NASA Astrophysics Data System (ADS)

Chen, Xia; Zhao, Bote; Cai, Yong; Tadé, Moses O.; Shao, Zongping

2013-11-01

Flexible V-O-C composite nanofibers were fabricated from solution precursors via electrospinning and were investigated as free-standing and additive-free film electrodes for supercapacitors. Specifically, composite nanofibers (V0, V5, V10 and V20) with different vanadyl acetylacetonate (VO(acac)2) contents of 0, 5, 10 and 20 wt% with respect to polyacrylonitrile (PAN) were prepared. The composite nanofibers were comparatively studied using XRD, Raman spectroscopy, XPS, N2 adsorption-desorption, FE-SEM, TEM and S-TEM. The vanadium element was found to be well-dispersed in the carbon nanofibers, free from the formation of an aggregated crystalline phase, even in the case of V20. A specific surface area of 587.9 m2 g-1 was reached for V10 after calcination, which is approximately twice that of the vanadium-free carbon nanofibers (V0, 300.9 m2 g-1). To perform as an electrode for supercapacitors in an aqueous electrolyte, the V10 film delivered a specific capacitance of 463 F g-1 at 1 A g-1. V10 was also able to retain a specific capacitance of 380 F g-1, even at a current density of 10 A g-1. Additionally, very stable cycling stability was achieved, maintaining an outstanding specific capacitance of 400 F g-1 at 5 A g-1 after charge-discharge cycling 5000 times. Thus, V-O-C composite nanofibers are highly attractive electrode materials for flexible, high-power, thin film energy storage devices and applications.Flexible V-O-C composite nanofibers were fabricated from solution precursors via electrospinning and were investigated as free-standing and additive-free film electrodes for supercapacitors. Specifically, composite nanofibers (V0, V5, V10 and V20) with different vanadyl acetylacetonate (VO(acac)2) contents of 0, 5, 10 and 20 wt% with respect to polyacrylonitrile (PAN) were prepared. The composite nanofibers were comparatively studied using XRD, Raman spectroscopy, XPS, N2 adsorption-desorption, FE-SEM, TEM and S-TEM. The vanadium element was found to be well-dispersed in the carbon nanofibers, free from the formation of an aggregated crystalline phase, even in the case of V20. A specific surface area of 587.9 m2 g-1 was reached for V10 after calcination, which is approximately twice that of the vanadium-free carbon nanofibers (V0, 300.9 m2 g-1). To perform as an electrode for supercapacitors in an aqueous electrolyte, the V10 film delivered a specific capacitance of 463 F g-1 at 1 A g-1. V10 was also able to retain a specific capacitance of 380 F g-1, even at a current density of 10 A g-1. Additionally, very stable cycling stability was achieved, maintaining an outstanding specific capacitance of 400 F g-1 at 5 A g-1 after charge-discharge cycling 5000 times. Thus, V-O-C composite nanofibers are highly attractive electrode materials for flexible, high-power, thin film energy storage devices and applications. Electronic supplementary information (ESI) available: FE-SEM image. See DOI: 10.1039/c3nr04484j

Self-Assembled Hierarchical Formation of Conjugated 3D Cobalt Oxide Nanobead-CNT-Graphene Nanostructure Using Microwaves for High-Performance Supercapacitor Electrode.

PubMed

Kumar, Rajesh; Singh, Rajesh Kumar; Dubey, Pawan Kumar; Singh, Dinesh Pratap; Yadav, Ram Manohar

2015-07-15

Here we report the electrochemical performance of a interesting three-dimensional (3D) structures comprised of zero-dimensional (0D) cobalt oxide nanobeads, one-dimensional (1D) carbon nanotubes and two-dimensional (2D) graphene, stacked hierarchically. We have synthesized 3D self-assembled hierarchical nanostructure comprised of cobalt oxide nanobeads (Co-nb), carbon nanotubes (CNTs), and graphene nanosheets (GNSs) for high-performance supercapacitor electrode application. This 3D self-assembled hierarchical nanostructure Co3O4 nanobeads-CNTs-GNSs (3D:Co-nb@CG) is grown at a large scale (gram) through simple, facile, and ultrafast microwave irradiation (MWI). In 3D:Co-nb@CG nanostructure, Co3O4 nanobeads are attached to the CNT surfaces grown on GNSs. Our ultrafast, one-step approach not only renders simultaneous growth of cobalt oxide and CNTs on graphene nanosheets but also institutes the intrinsic dispersion of carbon nanotubes and cobalt oxide within a highly conductive scaffold. The 3D:Co-nb@CG electrode shows better electrochemical performance with a maximum specific capacitance of 600 F/g at the charge/discharge current density of 0.7A/g in KOH electrolyte, which is 1.56 times higher than that of Co3O4-decorated graphene (Co-np@G) nanostructure. This electrode also shows a long cyclic life, excellent rate capability, and high specific capacitance. It also shows high stability after few cycles (550 cycles) and exhibits high capacitance retention behavior. It was observed that the supercapacitor retained 94.5% of its initial capacitance even after 5000 cycles, indicating its excellent cyclic stability. The synergistic effect of the 3D:Co-nb@CG appears to contribute to the enhanced electrochemical performances.

A novel and facile synthesis approach for a porous carbon/graphene composite for high-performance supercapacitors.

PubMed

Liu, Ting; Zhang, Xuesha; Liu, Kang; Liu, Yanyan; Liu, Mengjie; Wu, Wenyu; Gu, Yu; Zhang, Ruijun

2018-03-02

We propose a novel and facile synthesis approach to a porous carbon/graphene composite. Graphene is obtained from room-temperature expanded graphite (RTEG), not involving the use of graphite oxide (GO). Porous carbon is acquired by carbonization and KOH-activation of polyvinylpyrrolidone (PVP), which is used to exfoliate RTEG into graphene and inhibit the restacking of the resultant graphene in the present work. The prepared porous carbon/graphene composite has a high specific surface area (SSA) (3008 m 2 g -1 ) and a hierarchical micro- and meso- pore structure (dominant pores in the range of 1-5 nm). Electrochemical measurement demonstrates that the as-prepared porous carbon/graphene composite can deliver an outstanding specific capacitance of up to 340 F g -1 at 5 mV s -1 in 6 M KOH electrolyte. This specific capacitance is among the highest reported so far for porous carbon/graphene materials. Moreover, the prepared composite as an electrode material also exhibits excellent cycling stability (94.4% capacitance retention over 10 000 cycles). The as-fabricated symmetrical supercapacitor exhibits a high energy density of 10.9 W h kg -1 (based on total mass of electrode materials) and an outstanding energy density retention, even at high power density. Compared with conventional preparation routes for porous carbon/graphene composites, the present approach is significantly simple, convenient and cost-effective, which will make it more competent in the development of electrode materials for high-performance supercapacitors.

Three-Dimensional Tubular MoS2/PANI Hybrid Electrode for High Rate Performance Supercapacitor.

PubMed

Ren, Lijun; Zhang, Gaini; Yan, Zhe; Kang, Liping; Xu, Hua; Shi, Feng; Lei, Zhibin; Liu, Zong-Huai

2015-12-30

By using three-dimensional (3D) tubular molybdenum disulfide (MoS2) as both an active material in electrochemical reaction and a framework to provide more paths for insertion and extraction of ions, PANI nanowire arrays with a diameter of 10-20 nm can be controllably grown on both the external and internal surface of 3D tubular MoS2 by in situ oxidative polymerization of aniline monomers and 3D tubular MoS2/PANI hybrid materials with different amounts of PANI are prepared. A controllable growth of PANI nanowire arrays on the tubular MoS2 surface provides an opportunity to optimize the capacitive performance of the obtained electrodes. When the loading amount of PANI is 60%, the obtained MoS2/PANI-60 hybrid electrode not only shows a high specific capacitance of 552 F/g at a current density of 0.5 A/g, but also gives excellent rate capability of 82% from 0.5 to 30 A/g. The remarkable rate performance can be mainly attributed to the architecture with synergistic effect between 3D tubular MoS2 and PANI nanowire arrays. Moreover, the MoS2/PANI-60 based symmetric supercapacitor also exhibits the excellent rate performance and good cycling stability. The specific capacitance based on the total mass of the two electrodes is 124 F/g at a current density of 1 A/g and 79% of its initial capacitance is remained after 6000 cycles. The 3D tubular structure provides a good and favorable method for improving the capacitance retention of PANI electrode.

Popcorn-Derived Porous Carbon for Energy Storage and CO2 Capture.

PubMed

Liang, Ting; Chen, Chunlin; Li, Xing; Zhang, Jian

2016-08-16

Porous carbon materials have drawn tremendous attention due to its applications in energy storage, gas/water purification, catalyst support, and other important fields. However, producing high-performance carbons via a facile and efficient route is still a big challenge. Here we report the synthesis of microporous carbon materials by employing a steam-explosion method with subsequent potassium activation and carbonization of the obtained popcorn. The obtained carbon features a large specific surface area, high porosity, and doped nitrogen atoms. Using as an electrode material in supercapacitor, it displays a high specific capacitance of 245 F g(-1) at 0.5 A g(-1) and a remarkable stability of 97.8% retention after 5000 cycles at 5 A g(-1). The product also exhibits a high CO2 adsorption capacity of 4.60 mmol g(-1) under 1066 mbar and 25 °C. Both areal specific capacitance and specific CO2 uptake are directly proportional to the surface nitrogen content. This approach could thus enlighten the batch production of porous nitrogen-doped carbons for a wide range of energy and environmental applications.

Mesoporous composite nickel cobalt oxide/graphene oxide synthesized via a template-assistant co-precipitation route as electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Yanjie; Wang, Lincai; Cao, Peiqi; Cai, Chuanlin; Fu, Yanbao; Ma, Xiaohua

2016-02-01

A simple co-precipitation method utilizing SDS (sodium dodecyl sulfate) as template and ammonia as precipitant is successfully employed to synthesize nickel cobalt oxide/graphene oxide (NiCo2O4/GO) composite. The as-prepared composite (NCG-10) exhibits a high capacitance of 1211.25 F g-1, 687 F g-1 at the current density of 1 A g-1, 10 A g-1 and good cycling ability which renders NCG-10 as promising electrode material for supercapacitors. An asymmetric supercapacitor (ASC) (full button cell) has been constructed with NCG-10 as positive electrode and lab-made reduced graphene oxide (rGO) as negative electrode. The fabricated NCG-10//rGO with an extended stable operational voltage of 1.6 V can deliver a high specific capacitance of 144.45 F g-1 at a current density of 1 A g-1. The as-prepared NCG-10//rGO demonstrates remarkable energy density (51.36 W h kg-1 at 1 A g-1), high power density (50 kW kg-1 at 20 A g-1). The retention of capacitance is 88.6% at the current density of 8 A g-1 after 2000 cycles. The enhanced capacitive performance can be attributed to the improved specific surface area and 3D open area of NCG-10 generated by the pores and channels with the substantial function of SDS.

Synthesis and loading-dependent characteristics of nitrogen-doped graphene foam/carbon nanotube/manganese oxide ternary composite electrodes for high performance supercapacitors.

PubMed

Cheng, Tao; Yu, Baozhi; Cao, Linli; Tan, Huiyun; Li, Xinghua; Zheng, Xinliang; Li, Weilong; Ren, Zhaoyu; Bai, Jinbo

2017-09-01

The ternary composite electrodes, nitrogen-doped graphene foam/carbon nanotube/manganese dioxide (NGF/CNT/MnO 2 ), have been successfully fabricated via chemical vapor deposition (CVD) and facile hydrothermal method. The morphologies of the MnO 2 nanoflakes presented the loading-dependent characteristics and the nanoflake thickness could also be tuned by MnO 2 mass loading in the fabrication process. The correlation between their morphology and electrochemical performance was systematically investigated by controlling MnO 2 mass loading in the ternary composite electrodes. The electrochemical properties of the flexible ternary electrode (MnO 2 mass loading of 70%) exhibited a high areal capacitance of 3.03F/cm 2 and a high specific capacitance of 284F/g at the scan rate of 2mV/s. Moreover, it was interesting to find that the capacitance of the NGF/CNT/MnO 2 composite electrodes showed a 51.6% increase after 15,000 cycles. The gradual increase in specific capacitance was due to the formation of defective regions in the MnO 2 nanostructures during the electrochemical cycles of the electrodes, which further resulted in increased porosity, surface area, and consequently increased electrochemical capacity. This work demonstrates a rarely reported conclusion about loading-dependent characteristics for the NGF/CNT/MnO 2 ternary composite electrodes. It will bring new perspectives on designing novel ternary or multi-structure for various energy storage applications. Copyright © 2017 Elsevier Inc. All rights reserved.

Flexible pillared graphene-paper electrodes for high-performance electrochemical supercapacitors.

PubMed

Wang, Gongkai; Sun, Xiang; Lu, Fengyuan; Sun, Hongtao; Yu, Mingpeng; Jiang, Weilin; Liu, Changsheng; Lian, Jie

2012-02-06

Flexible graphene paper (GP) pillared by carbon black (CB) nanoparticles using a simple vacuum filtration method is developed as a high-performance electrode material for supercapacitors. Through the introduction of CB nanoparticles as spacers, the self-restacking of graphene sheets during the filtration process is mitigated to a great extent. The pillared GP-based supercapacitors exhibit excellent electrochemical performances and cyclic stabilities compared with GP without the addition of CB nanoparticles. At a scan rate of 10 mV s(-1) , the specific capacitance of the pillared GP is 138 F g(-1) and 83.2 F g(-1) with negligible 3.85% and 4.35% capacitance degradation after 2000 cycles in aqueous and organic electrolytes, respectively. At an extremely fast scan rate of 500 mV s (-1) , the specific capacitance can reach 80 F g(-1) in aqueous electrolyte. No binder is needed for assembling the supercapacitor cells and the pillared GP itself may serve as a current collector due to its intrinsic high electrical conductivity. The pillared GP has great potential in the development of promising flexible and ultralight-weight supercapacitors for electrochemical energy storage. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of mesoporous spinel NiCo2O4 using surfactant-assembled dispersion for asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Hsu, Chun-Tsung; Hu, Chi-Chang

2013-11-01

A simple and scalable process has been developed for synthesizing spinel NiCo2O4 nanocrystals through a thermal decomposition method. The introduction of hexadecyltrimethylammonium bromide (CTAB, (C16H33)N(CH3)3Br) into precursor solutions significantly enhances the homogeneity and porosity of spinel NiCo2O4. The porosity and high specific surface area of NiCo2O4 preserves the brilliant pseudo-capacitive performances due to providing smooth paths for electrolyte penetration and ion diffusion into inner active sites. Morphologies and microstructures of the active materials are examined by transmission electron microscopic (TEM) and X-ray diffraction (XRD) analyses. Thermogravimetric analysis (TGA) is used to evaluate the thermal properties of precursor solutions. The electrochemical performances of NiCo2O4 are systematically characterized by cyclic voltammetry and charge-discharge tests. Asymmetric supercapacitors are assembled with these brilliant binary oxides as the positive electrode and activated carbon as the negative electrode. The highly porous NiCo2O4 exhibits superior capacitive performances, i.e., high specific capacitance (764 F g-1 at 2 mV s-1) and long cycle life.

High Performance All-solid Supercapacitors Based on the Network of Ultralong Manganese dioxide/Polyaniline Coaxial Nanowires

NASA Astrophysics Data System (ADS)

Zhou, Junli; Yu, Lin; Liu, Wei; Zhang, Xiaodan; Mu, Wei; Du, Xu; Zhang, Zhe; Deng, Yulin

2015-12-01

In recent years, thin, lightweight and flexible solid supercapacitors are of considerable interest as energy storage devices. Here we demonstrated all-solid supercapacitors (SSCs) with high electrochemical properties, low self-discharge characteristics based on manganese dioxide/polyaniline (MNW/PANI) coaxial nanowire networks. The synergistic effect of MnO2/PANI plus the unique coaxial nanostructure of the ultralong nanowires with a highly interconnected network effectively enhance the conductivity and capacitive performance of the SSCs device. The MNW/PANI composite with 62.5% MnO2 exhibits an outstanding areal specific capacitance reaching 346 mF/cm2 at 5 mV s-1 which is significant higher than most previously reported solid supercapacitors (15.3 mF/cm2-109 mF/cm2) and is close to the that of the best graphene films solid state supercapacitors (372 mF/cm2). In contrast, only 190 mF/cm2 of areal specific capacitance was obtained for the pure MnO2 NW network. The supercapacitors also exhibited low leakage current as small as 20.1 μA, which demonstrated that the MNW/PANI SSCs have great potential for practical applications.

A two-step hydrothermal synthesis approach to synthesize NiCo2S4/NiS hollow nanospheres for high-performance asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Rui; Lin, Jianming; Wu, Jihuai; Huang, Miaoliang; Fan, Leqing; He, Xin; Wang, Yiting; Xu, Zedong

2017-11-01

In this work, a high-performance asymmetric supercapacitor device based on NiCo2S4/NiS hollow nanospheres as the positive electrode and the porous activated carbon as the negative electrode was successfully fabricated via a facile two-step hydrothermal synthesis approach. This NiCo2S4/NiS//activated carbon asymmetric supercapacitor achieved a high energy density of 43.7 Wh kg-1 at a power density of 160 W kg-1, an encouraging specific capacitance of 123 F g-1 at a current density of 1 mA cm-2, as well as a long-term performance with capacitance degradation of 5.2% after 3000 consecutive cycles at 1 mA cm-2. Moreover, the NiCo2S4/NiS electrode also demonstrated an excellent specific capacitance (1947.5 F g-1 at 3 mA cm-2) and an outstanding cycling stability (retaining 90.3% after 1000 cycles). The remarkable electrochemical performances may be attributed to the effect of NiS doping on NiCo2S4 which could enlarge the surface area and increase the surface roughness.

Utilizing Waste Thermocol Sheets and Rusted Iron Wires to Fabricate Carbon-Fe3O4 Nanocomposite Based Supercapacitors: Turning Wastes into Value-Added Materials.

PubMed

Vadiyar, Madagonda M; Liu, Xudong; Ye, Zhibin

2018-05-14

In the present work, we demonstrate the synthesis of porous activated carbon (specific surface area, 1,883 m2 g-1), Fe3O4 nanoparticles, and carbon-Fe3O4 nanocomposites using local waste thermocol sheets and rusted iron wires. The resulting carbon, Fe3O4 nanoparticles, and carbon-Fe3O4 composites are used as electrode materials for supercapacitor application. In particular, C-Fe3O4 composite electrodes exhibit a high specific capacitance of 1,375 F g-1 at 1 A g-1 and longer cyclic stability with 98 % of capacitance retention over 10,000 cycles. Subsequently, asymmetric supercapacitor, i. e., C-Fe3O4//Ni(OH)2/CNT device exhibits a high energy density of 91.1 Wh kg-1 and a remarkable cyclic stability, showing 98% of capacitance retention over 10,000 cycles. Thus, this work has important implications not only for the fabrication of low-cost electrodes for high-performance supercapacitors but also for the recycling of waste thermocol sheets and rust iron wires for value-added reuse. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Growth of highly mesoporous CuCo2O4@C core-shell arrays as advanced electrodes for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Yan, Hailong; Lu, Yang; Zhu, Kejia; Peng, Tao; Liu, Xianming; Liu, Yunxin; Luo, Yongsong

2018-05-01

A series of CuCo2O4 nanostructures with different morphologies were prepared by a hydrothermal method in combination with thermal treatment. The morphology, structure and composition were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. As the electrode materials for supercapacitors, CuCo2O4 nanoneedles delivered the highest specific capacitance compared with other CuCo2O4 nanostructures. Electrochemical performance measurements demonstrate that the carbon layer can improve the electrochemical stability of CuCo2O4 nanoneedles. The CuCo2O4@C electrode exhibits a high specific capacitance of 1432.4 F g-1 at a current density of 1 A g-1, with capacitance retention of 98.2% after 3000 circles. These characteristics of CuCo2O4@C composite are mainly due to the unique one dimensional needle-liked architecture and the conducting carbon, which provide a faster ion/electron transfer rate. These excellent performances of the CuCo2O4@C electrode confirmed the material as a positive electrode for hybrid supercapacitor application.

High Performance All-solid Supercapacitors Based on the Network of Ultralong Manganese dioxide/Polyaniline Coaxial Nanowires.

PubMed

Zhou, Junli; Yu, Lin; Liu, Wei; Zhang, Xiaodan; Mu, Wei; Du, Xu; Zhang, Zhe; Deng, Yulin

2015-12-08

In recent years, thin, lightweight and flexible solid supercapacitors are of considerable interest as energy storage devices. Here we demonstrated all-solid supercapacitors (SSCs) with high electrochemical properties, low self-discharge characteristics based on manganese dioxide/polyaniline (MNW/PANI) coaxial nanowire networks. The synergistic effect of MnO2/PANI plus the unique coaxial nanostructure of the ultralong nanowires with a highly interconnected network effectively enhance the conductivity and capacitive performance of the SSCs device. The MNW/PANI composite with 62.5% MnO2 exhibits an outstanding areal specific capacitance reaching 346 mF/cm(2) at 5 mV s(-1) which is significant higher than most previously reported solid supercapacitors (15.3 mF/cm(2)-109 mF/cm(2)) and is close to the that of the best graphene films solid state supercapacitors (372 mF/cm(2)). In contrast, only 190 mF/cm(2) of areal specific capacitance was obtained for the pure MnO2 NW network. The supercapacitors also exhibited low leakage current as small as 20.1 μA, which demonstrated that the MNW/PANI SSCs have great potential for practical applications.

Morphology controlled synthesis of monodisperse cobalt hydroxide for supercapacitor with high performance and long cycle life

NASA Astrophysics Data System (ADS)

Tang, Yongfu; Liu, Yanyan; Yu, Shengxue; Mu, Shichun; Xiao, Shaohua; Zhao, Yufeng; Gao, Faming

2014-06-01

A facile hydrothermal process with hexadecyltrimethyl ammonium bromide (CTAB) as the soft template is proposed to tune the morphology and size of cobalt hydroxide (Co(OH)2). Monodisperse β-phase Co(OH)2 nanowires with uniform size are obtained by controlling the CTAB content and the reaction time. Due to the uniform well-defined morphology and stable structure, the Co(OH)2 nanowires material exhibits high capacitive performance and long cycle life. The specific capacitance of the Co(OH)2 nanowires electrode is 358 F g-1 at 0.5 A g-1, and even 325 F g-1 at 10 A g-1. The specific capacitance retention is 86.3% after 5000 charge-discharge cycles at 2 A g-1. Moreover, the asymmetric supercapacitor is assembled with Co(OH)2 nanowires and nitrite acid treated activated carbon (NTAC), which shows an energy density of 13.6 Wh kg-1 at the power density of 153 W kg-1 under a high voltage of 1.6 V, and 13.1 Wh kg-1 even at the power density of 1.88 kW kg-1.

Hydrothermal synthesis of novel Mn3O4 nano-octahedrons with enhanced supercapacitors performances

NASA Astrophysics Data System (ADS)

Jiang, Hao; Zhao, Ting; Yan, Chaoyi; Ma, Jan; Li, Chunzhong

2010-10-01

Uniform and single-crystalline Mn3O4 nano-octahedrons have been successfully synthesized by a simple ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) assisted hydrothermal route. The octahedron structures exhibit a high geometric symmetry with smooth surfaces and the mean side length of square base of octahedrons is ~160 nm. The structure is reckoned to provide superior functional properties and the nano-size achieved in the present work is noted to further facilitate the material property enhancement. The formation process was proposed to begin with a ``dissolution-recrystallization'' which is followed by an ``Ostwald ripening'' mechanism. The Mn3O4 nano-octahedrons exhibited an enhanced specific capacitance of 322 F g-1 compared with the truncated octahedrons with specific capacitances of 244 F g-1, making them a promising electrode material for supercapacitors.Uniform and single-crystalline Mn3O4 nano-octahedrons have been successfully synthesized by a simple ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) assisted hydrothermal route. The octahedron structures exhibit a high geometric symmetry with smooth surfaces and the mean side length of square base of octahedrons is ~160 nm. The structure is reckoned to provide superior functional properties and the nano-size achieved in the present work is noted to further facilitate the material property enhancement. The formation process was proposed to begin with a ``dissolution-recrystallization'' which is followed by an ``Ostwald ripening'' mechanism. The Mn3O4 nano-octahedrons exhibited an enhanced specific capacitance of 322 F g-1 compared with the truncated octahedrons with specific capacitances of 244 F g-1, making them a promising electrode material for supercapacitors. Electronic supplementary information (ESI) available: TEM images; EDTA-2Na reaction details. See DOI: 10.1039/c0nr00257g

Surfactant-treated graphene covered polyaniline nanowires for supercapacitor electrode

NASA Astrophysics Data System (ADS)

Rajagopalan, Balasubramaniyan; Hur, Seung Hyun; Chung, Jin Suk

2015-04-01

Surfactant-treated graphene/polyaniline (G/PANI) nanocomposites were prepared by the MnO2 template-aided oxidative polymerization of aniline (ANI) on the surfactant-treated graphene sheets. The electrochemical performances of the G/PANI nanocomposites in a three-electrode system using an aqueous sulfuric acid as an electrolyte exhibited a specific capacitance of 436 F g-1 at 1 A g-1, which is much higher than the specific capacitance of pure PANI (367 F g-1). Such a higher specific capacitance of the G/PANI nanocomposite inferred an excellent synergistic effect of respective pseudocapacitance and electrical double-layer capacitance of PANI and graphene.

Assembly of flexible CoMoO4@NiMoO4·xH2O and Fe2O3 electrodes for solid-state asymmetric supercapacitors

PubMed Central

Wang, Jing; Zhang, Leipeng; Liu, Xusong; Zhang, Xiang; Tian, Yanlong; Liu, Xiaoxu; Zhao, Jiupeng; Li, Yao

2017-01-01

In this work, CoMoO4@NiMoO4·xH2O core-shell heterostructure electrode is directly grown on carbon fabric (CF) via a feasible hydrothermal procedure with CoMoO4 nanowires (NWs) as the core and NiMoO4 nanosheets (NSs) as the shell. This core-shell heterostructure could provide fast ion and electron transfer, a large number of active sites, and good strain accommodation. As a result, the CoMoO4@NiMoO4·xH2O electrode yields high-capacitance performance with a high specific capacitance of 1582 F g−1, good cycling stability with the capacitance retention of 97.1% after 3000 cycles and good rate capability. The electrode also shows excellent mechanical flexibility. Also, a flexible Fe2O3 nanorods/CF electrode with enhanced electrochemical performance was prepared. A solid-state asymmetric supercapacitor device is successfully fabricated by using flexible CoMoO4@NiMoO4·xH2O as the positive electrode and Fe2O3 as the negative electrode. The asymmetric supercapacitor with a maximum voltage of 1.6 V demonstrates high specific energy (41.8 Wh kg−1 at 700 W kg−1), high power density (12000 W kg−1 at 26.7 Wh kg−1), and excellent cycle ability with the capacitance retention of 89.3% after 5000 cycles (at the current density of 3A g−1). PMID:28106170

Free-standing 3D graphene/polyaniline composite film electrodes for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Wang, Shiyong; Ma, Li; Gan, Mengyu; Fu, Shenna; Dai, Wenqin; Zhou, Tao; Sun, Xiaowu; Wang, Huihui; Wang, Huining

2015-12-01

The research paper describes polyaniline (PANI) nanowires array on flexible polystyrene microsphere/reduced graphene (PS/rGN) film is synthesized by dilute polymerization, and then the PS microspheres are removed to form free-standing three-dimensional (3D) rGN/PANI composite film. The chemical and structural properties of the 3D rGN/PANI film are characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET), and the results confirm the 3D rGN/PANI film is synthesized successfully. When the film is used as a supercapacitor electrode, the maximum specific capacitance is as high as 740 F g-1 (or 581 F cm-3 for volumetric capacitance) at a current density of 0.5 A g-1 and the specific capacitance retains 87% of the initial after constant charge-discharge 1000 cycles at current density of 10 A g-1. It is believed that the free-standing 3D rGN/PANI film will have a great potential for application in supercapacitors.

Flower-like Copper Cobaltite Nanosheets on Graphite Paper as High-Performance Supercapacitor Electrodes and Enzymeless Glucose Sensors.

PubMed

Liu, Shude; Hui, K S; Hui, K N

2016-02-10

Flower-like copper cobaltite (CuCo2O4) nanosheets anchored on graphite paper have been synthesized using a facile hydrothermal method followed by a postannealing treatment. Supercapacitor electrodes employing CuCo2O4 nanosheets exhibit an enhanced capacitance of 1131 F g(-1) at a current density of 1 A g(-1) compared with previously reported supercapacitor electrodes. The CuCo2O4 electrode delivers a specific capacitance of up to 409 F g(-1) at a current density of as high as 50 A g(-1), and a good long-term cycling stability, with 79.7% of its specific capacitance retained after 5000 cycles at 10 A g(-1). Furthermore, the as-prepared CuCo2O4 nanosheets on graphite paper can be fabricated as electrodes and used as enzymeless glucose sensors, which exhibit good sensitivity (3.625 μA μM(-1) cm(-2)) and an extraordinary linear response ranging up to 320 μM with a low detection limit (5 μM).

Hydrothermal synthesis of nanostructured graphene/polyaniline composites as high-capacitance electrode materials for supercapacitors

PubMed Central

Wang, Ronghua; Han, Meng; Zhao, Qiannan; Ren, Zonglin; Guo, Xiaolong; Xu, Chaohe; Hu, Ning; Lu, Li

2017-01-01

As known to all, hydrothermal synthesis is a powerful technique for preparing inorganic and organic materials or composites with different architectures. In this reports, by controlling hydrothermal conditions, nanostructured polyaniline (PANi) in different morphologies were composited with graphene sheets (GNS) and used as electrode materials of supercapacitors. Specifically, ultrathin PANi layers with total thickness of 10–20 nm are uniformly composited with GNS by a two-step hydrothermal-assistant chemical oxidation polymerization process; while PANi nanofibers with diameter of 50~100 nm are obtained by a one-step direct hydrothermal process. Benefitting from the ultrathin layer and porous structure, the sheet-like GNS/PANi composites can deliver specific capacitances of 532.3 to 304.9 F/g at scan rates of 2 to 50 mV/s. And also, this active material showed very good stability with capacitance retention as high as ~99.6% at scan rate of 50 mV/s, indicating a great potential for using in supercapacitors. Furthermore, the effects of hydrothermal temperatures on the electrochemical performances were systematically studied and discussed. PMID:28291246

Synthesis of NiMn-LDH Nanosheet@Ni3S2 Nanorod Hybrid Structures for Supercapacitor Electrode Materials with Ultrahigh Specific Capacitance.

PubMed

Yu, Shuai; Zhang, Yingxi; Lou, Gaobo; Wu, Yatao; Zhu, Xinqiang; Chen, Hao; Shen, Zhehong; Fu, Shenyuan; Bao, Binfu; Wu, Limin

2018-03-27

One of the key challenges for pseudocapacitive electrode materials with highly effective capacitance output and future practical applications is how to rationally construct hierarchical and ordered hybrid nanoarchitecture through the simple process. Herein, we design and synthesize a novel NiMn-layered double hydroxide nanosheet@Ni 3 S 2 nanorod hybrid array supported on porous nickel foam via a one-pot hydrothermal method. Benefited from the ultrathin and rough nature, the well-defined porous structure of the hybrid array, as well as the synergetic effect between NiMn-layered double hydroxide nanosheets and Ni 3 S 2 nanorods, the as-fabricated hybrid array-based electrode exhibits an ultrahigh specific capacitance of 2703 F g -1 at 3 A g -1 . Moreover, the asymmetric supercapacitor with this hybrid array as a positive electrode and wood-derived activated carbon as a negative electrode demonstrates high energy density (57 Wh Kg -1 at 738 W Kg -1 ) and very good electrochemical cycling stability.

A high-performance supercapacitor electrode based on N-doped porous graphene

NASA Astrophysics Data System (ADS)

Dai, Shuge; Liu, Zhen; Zhao, Bote; Zeng, Jianhuang; Hu, Hao; Zhang, Qiaobao; Chen, Dongchang; Qu, Chong; Dang, Dai; Liu, Meilin

2018-05-01

The development of high-performance supercapacitors (SCs) often faces some contradictory and competing requirements such as excellent rate capability, long cycling life, and high energy density. One effective strategy is to explore electrode materials of high capacitance, electrode architectures of fast charge and mass transfer, and electrolytes of wide voltage window. Here we report a facile and readily scalable strategy to produce high-performance N-doped graphene with a high specific capacitance (∼390 F g-1). A symmetric SC device with a wide voltage window of 3.5 V is also successfully fabricated based on the N-doped graphene electrode. More importantly, the as-assembled symmetric SC delivers a high energy density of 55 Wh kg-1 at a power density of 1800 W kg-1 while maintaining superior cycling life (retaining 96.6% of the initial capacitance after 20,000 cycles). Even at a power density as high as 8800 W kg-1, it still retains an energy density of 29 Wh kg-1, higher than those of previously reported graphene-based symmetric SCs.

Wet-spun, porous, orientational graphene hydrogel films for high-performance supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Kou, Liang; Liu, Zheng; Huang, Tieqi; Zheng, Bingna; Tian, Zhanyuan; Deng, Zengshe; Gao, Chao

2015-02-01

Supercapacitors with porous electrodes of graphene macroscopic assembly are supposed to have high energy storage capacity. However, a great number of ``close pores'' in porous graphene electrodes are invalid because electrolyte ions cannot infiltrate. A quick method to prepare porous graphene electrodes with reduced ``close pores'' is essential for higher energy storage. Here we propose a wet-spinning assembly approach based on the liquid crystal behavior of graphene oxide to continuously spin orientational graphene hydrogel films with ``open pores'', which are used directly as binder-free supercapacitor electrodes. The resulting supercapacitor electrodes show better electrochemical performance than those with disordered graphene sheets. Furthermore, three reduction methods including hydrothermal treatment, hydrazine and hydroiodic acid reduction are used to evaluate the specific capacitances of the graphene hydrogel film. Hydrazine-reduced graphene hydrogel film shows the highest capacitance of 203 F g-1 at 1 A g-1 and maintains 67.1% specific capacitance (140 F g-1) at 50 A g-1. The combination of scalable wet-spinning technology and orientational structure makes graphene hydrogel films an ideal electrode material for supercapacitors.Supercapacitors with porous electrodes of graphene macroscopic assembly are supposed to have high energy storage capacity. However, a great number of ``close pores'' in porous graphene electrodes are invalid because electrolyte ions cannot infiltrate. A quick method to prepare porous graphene electrodes with reduced ``close pores'' is essential for higher energy storage. Here we propose a wet-spinning assembly approach based on the liquid crystal behavior of graphene oxide to continuously spin orientational graphene hydrogel films with ``open pores'', which are used directly as binder-free supercapacitor electrodes. The resulting supercapacitor electrodes show better electrochemical performance than those with disordered graphene sheets. Furthermore, three reduction methods including hydrothermal treatment, hydrazine and hydroiodic acid reduction are used to evaluate the specific capacitances of the graphene hydrogel film. Hydrazine-reduced graphene hydrogel film shows the highest capacitance of 203 F g-1 at 1 A g-1 and maintains 67.1% specific capacitance (140 F g-1) at 50 A g-1. The combination of scalable wet-spinning technology and orientational structure makes graphene hydrogel films an ideal electrode material for supercapacitors. Electronic supplementary information (ESI) available: The schematic diagram for fabricating graphene oxide hydrogel films, stress-strain curves and TGA curves of three GHFs, a digital photo of the test device for the two-electrode system, and comparison of the electrochemical performance of our GHF-HZ supercapacitors. See DOI: 10.1039/c4nr07038k

Biomass derived nitrogen-doped hierarchical porous carbon sheets for supercapacitors with high performance.

PubMed

Wang, Cunjing; Wu, Dapeng; Wang, Hongju; Gao, Zhiyong; Xu, Fang; Jiang, Kai

2018-08-01

A facile potassium chloride salt-locking technique combined with hydrothermal treatment on precursors was explored to prepare nitrogen-doped hierarchical porous carbon sheets in air from biomass. Benefiting from the effective synthesis strategy, the as-obtained carbon possesses a unique nitrogen-doped thin carbon sheet structure with abundant hierarchical pores and large specific surface areas of 1459 m 2  g -1 . The doped nitrogen in carbon framework has a positive effect on the electrochemical properties of the electrode material, the thin carbon sheet structure benefits for fast ion transfer, the abundant meso-pores provide convenient channels for rapid charge transportation, large specific surface area and lots of micro-pores guarantee sufficient ion-storage sites. Therefore, applied for supercapacitors, the carbon electrode material exhibits an outstanding specific capacitance of 451 F g -1 at 0.5 A g -1 in a three-electrode system. Moreover, the assembled symmetric supercapacitor based on two identical carbon electrodes also displays high specific capacitance of 309 F g -1 at 0.5 A g -1 , excellent rate capacity and remarkable cycling stability with 99.3% of the initial capacitance retention after 10,000 cycles at 5 A -1 . The synthesis strategy avoids expensive inert gas protection and the use of corrosive KOH and toxic ZnCl 2 activated reagents, representing a promising green route to design advanced carbon electrode materials from biomass for high-capacity supercapacitors. Copyright © 2018. Published by Elsevier Inc.

Mechanochemistry-assisted synthesis of hierarchical porous carbons applied as supercapacitors

PubMed Central

Leistenschneider, Desirée; Jäckel, Nicolas; Hippauf, Felix; Presser, Volker

2017-01-01

A solvent-free synthesis of hierarchical porous carbons is conducted by a facile and fast mechanochemical reaction in a ball mill. By means of a mechanochemical ball-milling approach, we obtained titanium(IV) citrate-based polymers, which have been processed via high temperature chlorine treatment to hierarchical porous carbons with a high specific surface area of up to 1814 m2 g−1 and well-defined pore structures. The carbons are applied as electrode materials in electric double-layer capacitors showing high specific capacitances with 98 F g−1 in organic and 138 F g−1 in an ionic liquid electrolyte as well as good rate capabilities, maintaining 87% of the initial capacitance with 1 M TEA-BF4 in acetonitrile (ACN) and 81% at 10 A g−1 in EMIM-BF4. PMID:28781699

Micro-mesoporous carbon spheres derived from carrageenan as electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Fan, Yang; Yang, Xin; Zhu, Bing; Liu, Pei-Fang; Lu, Hai-Ting

2014-12-01

The polysaccharide carrageenan is used as a natural precursor to prepare micro-mesoporous carbon spheres. The carbon spheres were synthesized by hydrothermal carbonization of carrageenan, and subsequent chemical activation by KOH at different temperatures. The obtained micro-mesoporous carbon spheres have high surface area (up to 2502 m2 g-1) and large pore volume (up to 1.43 cm3 g-1). Moreover, the micro- and mesoporosity can be finely tuned be modifying the activation temperatures in the range of 700-900 °C. The carbon spheres activated at 900 °C present high specific capacitance of 230 F g-1 at a current density of 1 A g-1 and good ion transport kinetics. The good capacitive performance can be ascribed to the high specific surface area, well-controlled micro- and mesoporosity and narrow pore size distribution.

Three-dimensional cotton-like nickel nanowire@Ni-Co hydroxide nanosheet arrays as binder-free electrode for high-performance asymmetric supercapacitor

NASA Astrophysics Data System (ADS)

Wan, Houzhao; Li, Lang; Xu, Yang; Tan, Qiuyang; Liu, Xiang; Zhang, Jun; Wang, Hanbin; Wang, Hao

2018-05-01

Three-dimensional (3D) cotton-like Ni-Co layered double hydroxide nanosheet arrays/nickel nanowires (3D Ni-Co LDH/NiNw) were successfully fabricated through a facile chemical bath deposition method. The 3D nickel nanowires are used as a conductive substrate with robust adhesion for high-pseudocapacitance Ni-Co LDH. The 3D Ni-Co LDH/NiNw electrode shows a high areal specific capacitance of 14 F cm-2 at 5 mA cm-2 and quality specific capacitance of 466.6 F g-1 at 0.125 A g-1 with respect to the whole quality of the electrode. The fabricated asymmetric supercapacitor exhibits a remarkable energy density of 0.387 mWh cm-2 using Ni-Co LDH/NiNw as the negative electrode. This high-performance composite electrode presents a new and affordable general approach for supercapacitors.

Nitrogen and phosphorus co-doped carbon hollow spheres derived from polypyrrole for high-performance supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Lv, Bingjie; Li, Peipei; Liu, Yan; Lin, Shanshan; Gao, Bifen; Lin, Bizhou

2018-04-01

Nitrogen and phosphorus co-doped carbon hollow spheres (NPCHSs) have been prepared by a carbonization and subsequent chemical activation route using dehydrated polypyrrole hollow spheres as the precursor and KOH as the activating agent. NPCHSs are interconnected into a unique 3D porous network, which endows the as-prepared carbon to exhibit a large specific surface area of 1155 m2 g-1 and a high specific capacitance of 232 F g-1 at a current density of 1 A g-1. The as-obtained NPCHSs present a high-level heteroatom doping with N, O and P contents of 11.4, 6.7 and 3.5 wt%, respectively. The capacitance of NPCHSs has been retained at 89.1% after 5000 charge-discharge cycles at a relatively high current density of 5 A g-1. Such excellent performance suggests that NPCHSs are attractive electrode candidates for electrical double layer capacitors.

Three-dimensional cotton-like nickel nanowire@Ni-Co hydroxide nanosheet arrays as binder-free electrode for high-performance asymmetric supercapacitor.

PubMed

Wan, Houzhao; Li, Lang; Xu, Yang; Tan, Qiuyang; Liu, Xiang; Zhang, Jun; Wang, Hanbin; Wang, Hao

2018-05-11

Three-dimensional (3D) cotton-like Ni-Co layered double hydroxide nanosheet arrays/nickel nanowires (3D Ni-Co LDH/NiNw) were successfully fabricated through a facile chemical bath deposition method. The 3D nickel nanowires are used as a conductive substrate with robust adhesion for high-pseudocapacitance Ni-Co LDH. The 3D Ni-Co LDH/NiNw electrode shows a high areal specific capacitance of 14 F cm -2 at 5 mA cm -2 and quality specific capacitance of 466.6 F g -1 at 0.125 A g -1 with respect to the whole quality of the electrode. The fabricated asymmetric supercapacitor exhibits a remarkable energy density of 0.387 mWh cm -2 using Ni-Co LDH/NiNw as the negative electrode. This high-performance composite electrode presents a new and affordable general approach for supercapacitors.

Rod-like polyaniline supported on three-dimensional boron and nitrogen-co-doped graphene frameworks for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Liao, Kexuan; Gao, Jialu; Fan, Jinchen; Mo, Yao; Xu, Qunjie; Min, Yulin

2017-12-01

In this work, novel three-dimensional (3D) boron and nitrogen-co-doped three-dimensional (3D) graphene frameworks (BN-GFs) supporting rod-like polyaniline (PANI) are facilely prepared and used as electrodes for high-performance supercapacitors. The results demonstrated that BN-GFs with tuned electronic structure can not only provide a large surface area for rod-like PANI to anchor but also effectively facilitate the ion transfer and charge storage in the electrode. The PANI/BN-GF composite with wrinkled boron and nitrogen-co-doped graphene sheets interconnected by rod-like PANI exhibits excellent capacitive properties with a maximum specific capacitance of 596 F/g at a current density of 0.5 A/g. Notably, they also show excellent cycling stability with more than 81% capacitance retention after 5000 charge-discharge cycles.

Preparation of layered graphene and tungsten oxide hybrids for enhanced performance supercapacitors.

PubMed

Xing, Ling-Li; Huang, Ke-Jing; Fang, Lin-Xia

2016-11-01

Tungsten oxide (WO 3 ), which was originally poor in capacitive performance, is made into an excellent electrode material for supercapacitors by dispersing it on graphene (Gr). The obtained Gr-WO 3 hybrids are characterized by X-ray diffraction, Raman spectroscopy, high-resolution transmission electron microscopy and scanning electron microscopy techniques, and evaluated as electrode materials for high-performance supercapacitors by cyclic voltammetry, galvanostatic charge-discharge curves and electrochemical impedance spectroscopy. A great improvement in specific capacitance is achieved with the present hybrids, from 255 F g -1 for WO 3 nanoparticles to 580 F g -1 for Gr-WO 3 hybrids (scanned at 1 A g -1 in 2 M KOH over a potential window of 0 to 0.45 V). The Gr-WO 3 hybrid exhibits an excellent high rate capability and good cycling stability with more than 92% capacitance retention over 1000 cycles at a current density of 5 A g -1 . The enhancement in supercapacitor performance of Gr-WO 3 is not only attributed to its unique nanostructure with large specific surface area, but also its excellent electro-conductivity, which facilitates efficient charge transport and promotes electrolyte diffusion. As a whole, this work indicates that Gr-WO 3 hybrids are a promising electrode material for high-performance supercapacitors.

Design and Tailoring of the 3D Macroporous Hydrous RuO2 Hierarchical Architectures with a Hard-Template Method for High-Performance Supercapacitors.

PubMed

Peng, Zhikun; Liu, Xu; Meng, Huan; Li, Zhongjun; Li, Baojun; Liu, Zhongyi; Liu, Shouchang

2017-02-08

In this work, RuO 2 honeycomb networks (RHCs) and hollow spherical structures (RHSs) were rationally designed and synthesized with modified-SiO 2 as a sacrificial template via two hydrothermal approaches. At a high current density of 20 A g -1 , the two hierarchical porous RuO 2 ·xH 2 O frameworks showed the specific capacitance as high as 628 and 597 F g -1 ; this is about 80% and 75% of the capacitance retention of 0.5 A g -1 for RHCs and RHSs, respectively. Even after 4000 cycles at 5 A g -1 , the RHCs and RHSs can still remain at 86% and 91% of their initial specific capacitances, respectively. These two hierarchical frameworks have a well-defined pathway that benefits for the transmission/diffusion of electrolyte and surface redox reactions. As a result, they exhibit good supercapacitor performance in both acid (H 2 SO 4 ) and alkaline (KOH) electrolytes. As compared to RuO 2 bulk structure and similar RuO 2 counterpart reported in pseudocapacitors, the two hierarchical porous RuO 2 ·xH 2 O frameworks have better energy storage capabilities, high-rate performance, and excellent cycling stability.

A three-dimensional graphene aerogel containing solvent-free polyaniline fluid for high performance supercapacitors.

PubMed

Gao, Zhaodongfang; Yang, Junwei; Huang, Jing; Xiong, Chuanxi; Yang, Quanling

2017-11-23

Conducting polymer based supercapacitors usually suffer from the difficulty of achieving high specific capacitance and good long-term stability simultaneously. In this communication, a long-chain protonic acid doped solvent-free self-suspended polyaniline (S-PANI) fluid and reduced graphene oxide (RGO) were used to fabricate a three-dimensional RGO/S-PANI aerogel via a simple self-assembled hydrothermal method, which was then applied as a supercapacitor electrode. This 3D RGO/S-PANI composite exhibited a high specific capacitance of up to 480 F g -1 at a current density of 1 A g -1 and 334 F g -1 even at a high discharge rate of 40 A g -1 . An outstanding cycling performance, with 96.14% of the initial capacitance remaining after 10 000 charging/discharging cycles at a rate of 10 A g -1 , was also achieved. Compared with the conventional conducting polymer materials, the 3D RGO/S-PANI composite presented more reliable rate capability and cycling stability. Moreover, S-PANI possesses excellent processability, thereby revealing its enormous potential in large scale production. We anticipate that the solvent-free fluid technique is also applicable to the preparation of other 3D graphene/polymer materials for energy storage.

High-performance carbon-coated ZnMn2O4 nanocrystallite supercapacitors with tailored microstructures enabled by a novel solution combustion method

NASA Astrophysics Data System (ADS)

Abdollahifar, Mozaffar; Huang, Sheng-Siang; Lin, Yu-Hsiang; Lin, Yan-Cheng; Shih, Bing-Yi; Sheu, Hwo-Shuenn; Liao, Yen-Fa; Wu, Nae-Lih

2018-02-01

Although ZnMn2O4 is widely studied as Li-ion battery anodes, it remains a challenge to tailor suitable microstructures of the oxide for supercapacitor applications. Carbon-coated ZnMn2O4 (C@ZMO) nanocrystallites showing high-performance pseudocapacitor behaviours in neutral aqueous electrolyte are for the first time successfully synthesised via a novel solution combustion process using polyethylene glycol as a multifunctional microstructure-directing agent. Controlling the molecular weight and amount of the polymer in the combustion solution enables the formation of highly-crystalline C@ZMO having substantially higher, by more than 5 folds, specific surface areas with mesoporous structures and conformal carbon coating via the one-pot synthesis process. The resulting C@ZMO supercapacitor electrodes in Na2SO4(aq) electrolyte exhibit ideal capacitive behaviours with specific capacitances up to 150 F g-1 and cycle stability showing no capacitance fade after 10,000 cycles at 60% of full capacity and >99% Coulombic efficiency. This study not only illustrates a new powerful synthesis route capable of producing conductive mesoporous crystalline oxide-based nanomaterials for energy storage applications but also reveals a new class of high-performance pseudocapacitive materials for neutral aqueous electrolytes.

In situ electrochemical polymerization of a nanorod-PANI-Graphene composite in a reverse micelle electrolyte and its application in a supercapacitor.

PubMed

Hu, Liwen; Tu, Jiguo; Jiao, Shuqiang; Hou, Jungang; Zhu, Hongmin; Fray, Derek J

2012-12-05

Highly porous nanorod-PANI-Graphene composite films were prepared by in situ electrochemical polymerization onto an ITO substrate in a reverse micelle electrolyte. The morphology and microstructure of the composite films were analyzed by using a field emission scanning electron microscope. It was observed that the films were highly porous and the nanorod PANI films were inserted by graphene nanosheets. This indicated that a good conductive network between PANI nanorods and graphene sheets was formed. Further electrochemical tests involved cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 1 mol L(-1) HClO(4) solution. The results showed that the composite film had a favorable capacitance with a high electron transfer rate and low resistance. The highest specific capacitance that could be achieved was as high as 878.57 F g(-1) with the charge loading of 500 mC at a current density of 1 A g(-1). The GCD at different charge loadings showed good cycle stability with a low fading rate of specific capacitance after 1000 cycles. The results demonstrated that the nanorod-PANI-Graphene composite was proved to be of great potential as an electrode material for supercapacitors.

MnO2-deposited lignin-based carbon nanofiber mats for application as electrodes in symmetric pseudocapacitors.

PubMed

Youe, Won-Jae; Kim, Seok Ju; Lee, Soo-Min; Chun, Sang-Jin; Kang, Juwon; Kim, Yong Sik

2018-06-01

Low-cost, high-performance electrodes are highly attractive for practical supercapacitor applications. MnO 2 -deposited carbon nanofiber mats (MnO 2 -CNFMs) are prepared for use as binder-free supercapacitor electrodes. MnO 2 is deposited on the mats in situ by hydrothermally decomposing aqueous KMnO 4 , leading to the formation of nanocrystals of MnO 2 . The MnO 2 -CNFM electrode produced with 38.0μmol KMnO 4 (this electrode) shows a high specific capacitance of ~171.6F·g -1 at a scan rate of 5mV·s -1 . Moreover, a symmetric supercapacitor with the electrode exhibits a specific capacitance of 67.0F·g -1 , an energy density of 6.0Wh·kg -1 and a power density of 160W·kg -1 at a special current of 0.1A·g -1 . Further, the symmetric supercapacitor displays excellent cycling stability, retains approximately 99% of the capacitance after 1000cycles. The simplicity and ease of preparation of the MnO 2 -CNFMs as well as their suitability for use in coin-type supercapacitor cells make them ideal for application in cost-effective and high-performance electrodes for supercapacitors. Copyright © 2018 Elsevier B.V. All rights reserved.

Highly Self-Healable 3D Microsupercapacitor with MXene-Graphene Composite Aerogel.

PubMed

Yue, Yang; Liu, Nishuang; Ma, Yanan; Wang, Siliang; Liu, Weijie; Luo, Cheng; Zhang, Hang; Cheng, Feng; Rao, Jiangyu; Hu, Xiaokang; Su, Jun; Gao, Yihua

2018-05-22

High-performance microsupercapacitors (MSCs) with three-dimensional (3D) structure provide an effective approach to improve the ability of energy storage. Because the electrodes with 3D structure are generally easily destroyed under mechanical deformation in practical applications, we fabricated a self-healable 3D MSC consisting of MXene (Ti 3 C 2 T x )-graphene (reduced graphene oxide, rGO) composite aerogel electrode by wrapping it with a self-healing polyurethane as an outer shell. The MXene-rGO composite aerogel combining large specific surface area of rGO and high conductivity of the MXene can not only prevent the self-restacking of the lamella structure but also resist the poor oxidization of MXene to a degree. The MSC based on a 3D MXene-rGO aerogel delivers a large area specific capacitance of 34.6 mF cm -2 at a scan rate of 1 mV s -1 and an outstanding cycling performance with a capacitance retention up to 91% over 15 000 cycles. The 3D MSC presents an excellent self-healing ability with specific capacitance retention of 81.7% after the fifth healing. The preparation of this self-healable 3D MSC can provide a method for designing and manufacturing next-generation long-life multifunctional electronic devices further to meet the requirements of sustainable development.

Synthesis and Microstructural Characterization of Manganese Oxide Electrodes for Application as Electrochemical Supercapacitors

NASA Astrophysics Data System (ADS)

Babakhani, Banafsheh

The aim of this thesis work was to synthesize Mn-based oxide electrodes with high surface area structures by anodic electrodeposition for application as electrochemical capacitors. Rod-like structures provide large surface areas leading to high specific capacitances. Since templated electrosynthesis of rods is not easy to use in practical applications, it is more desirable to form rod-like structures without using any templates. In this work, Mn oxide electrodes with rod-like structures (˜1.5 µm in diameter) were synthesized from a solution of 0.01 M Mn acetate under galvanostatic control without any templates, on Au coated Si substrates. The electrochemical properties of the synthesized nanocrystalline electrodes were investigated to determine the effect of morphology, chemistry and crystal structure on the corresponding electrochemical behavior of Mn oxide electrodes. Mn oxides prepared at different current densities showed a defective antifluoritetype crystal structure. The rod-like Mn oxide electrodes synthesized at low current densities (5 mAcm.2) exhibited a high specific capacitance due to their large surface areas. Also, specific capacity retention after 250 cycles in an aqueous solution of 0.5 M Na2SO4 at 100 mVs -1 was about 78% of the initial capacity (203 Fg-1 ). To improve the electrochemical capacitive behavior of Mn oxide electrodes, a sequential approach and a one-step method were adopted to synthesize Mn oxide/PEDOT electrodes through anodic deposition on Au coated Si substrates from aqueous solutions. In the former case, free standing Mn oxide rods (about 10 µm long and less than 1.5 µm in diameter) were first synthesized, then coated by electro-polymerization of a conducting polymer (PEDOT) giving coaxial rods. The one-step, co-electrodeposition method produced agglomerated Mn oxide/PEDOT particles. The electrochemical behavior of the deposits depended on the morphology and crystal structure of the fabricated electrodes, which were affected by the composition and pH of the electrolyte, temperature, current density and polymer deposition time. Mn oxide/PEDOT coaxial core/shell rods consisted of MnO2 with an antifluorite-type structure coated with amorphous PEDOT. The Mn oxide/PEDOT coaxial core/shell electrodes prepared by the sequential method showed significantly better specific capacity and redox performance properties relative to both uncoated Mn oxide rods and co- electrodeposited Mn oxide/PEDOT electrodes. The best specific capacitance for Mn oxide/PEDOT rods produced sequentially was ˜295 F g-1 with ˜92% retention after 250 cycles in 0.5 M Na2SO4 at 100 mV s-1. To further improve the electrochemical capacitive behavior of Mn oxide electrodes, Co-doped and Fe-doped Mn oxide electrodes with a rod-like morphology and antifluorite-type crystal structure were synthesized by anodic electrodeposition, on Au coated Si substrates, from dilute solutions of Mn acetate and Co sulphate and Mn acetate and Fe chloride. Also, Mn-Co oxide/PEDOT coaxial core/shell rods were synthesized by applying a shell of PEDOT on Mn-Co oxide electrodes. Mn-Co oxide/PEDOT electrodes consisted of MnO2, with partial Co 2+ and Co3+ ion substitution for Mn4+, and amorphous PEDOT. Mn-Fe oxide electrodes consisted of MnO2, with partial Fe2+ and Fe3+ ion substitution for Mn4+. Electrochemical analysis showed that the capacitance values for all deposits increased with increasing scan rate to 100 mVs -1, and then decreased after 100 mVs-1. The Mn-Co oxide/PEDOT electrodes showed improved specific capacity and electrochemical cyclability relative to uncoated Mn-Co oxides and Mn-Fe oxides. Mn-Co oxide/PEDOT electrodes with rod-like structures had high capacitances (up to 310 Fg -1) at a scan rate of 100 mVs-1 and maintained their capacitance after 500 cycles in 0.5 M Na2SO4 (91% retention). Capacitance reduction for the deposits was mainly due to the loss of Mn ions by dissolution in the electrolyte solution. To better understand the nucleation and growth mechanisms of Mn oxide electrodes, the effects of supersaturation ratio on the morphology and crystal structure of electrodeposited Mn oxide were studied. By changing deposition parameters, including deposition current density, electrolyte composition, pH and temperature, a series of nanocrystalline Mn oxide electrodes with various morphologies (continuous coatings, rod-like structures, aggregated rods and thin sheets) and an antifluorite-type crystal structure was obtained. Mn oxide thin sheets showed instantaneous nucleation and single crystalline growth; rods had a mix of instantaneous/progressive nucleation and polycrystalline growth and continuous coatings formed by progressive nucleation and polycrystalline growth. Electrochemical analysis revealed the best capacitance behaviour obtained for Mn oxide thin sheets followed by Mn oxide rods, with dimensions on the microscale, and then continuous coatings. The highest specific capacitance (˜230 Fg-1) and capacitance retention rates (˜88%) were obtained for Mn oxide thin sheets after 250 cycles in 0.5 M Na2 SO4 at 20 mVs-1.

Porous carbon with a large surface area and an ultrahigh carbon purity via templating carbonization coupling with KOH activation as excellent supercapacitor electrode materials

NASA Astrophysics Data System (ADS)

Sun, Fei; Gao, Jihui; Liu, Xin; Pi, Xinxin; Yang, Yuqi; Wu, Shaohua

2016-11-01

Large surface area and good structural stability, for porous carbons, are two crucial requirements to enable the constructed supercapacitors with high capacitance and long cycling lifespan. Herein, we successfully prepare porous carbon with a large surface area (3175 m2 g-1) and an ultrahigh carbon purity (carbon atom ratio of 98.25%) via templating carbonization coupling with KOH activation. As-synthesized MTC-KOH exhibits excellent performances as supercapacitor electrode materials in terms of high specific capacitance and ultrahigh cycling stability. In a three electrode system, MTC-KOH delivers a high capacitance of 275 F g-1 at 0.5 A g-1 and still 120 F g-1 at a high rate of 30 A g-1. There is almost no capacitance decay even after 10,000 cycles, demonstrating outstanding cycling stability. In comparison, pre-activated MTC with a hierarchical pore structure shows a better rate capability than microporous MTC-KOH. Moreover, the constructed symmetric supercapacitor using MTC-KOH can achieve high energy densities of 8.68 Wh kg-1 and 4.03 Wh kg-1 with the corresponding power densities of 108 W kg-1 and 6.49 kW kg-1, respectively. Our work provides a simple design strategy to prepare highly porous carbons with high carbon purity for supercapacitors application.

Porous dimanganese trioxide microflowers derived from microcoordinations for flexible solid-state asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Pang, Huan; Li, Xinran; Li, Bing; Zhang, Yizhou; Zhao, Qunxing; Lai, Wen-Yong; Huang, Wei

2016-06-01

Dimanganese trioxide microflowers are easily obtained from a Mn(ii) 8-hydroxyquinoline microcoordination after calcination in air. We also look into the possible formation mechanism of the flower-like morphology, and find that the reaction time affects the morphology of the coordination. Furthermore, the as-prepared porous Mn2O3 microflowers are made of many nanoplates which form many nanogaps and nanochannels. Interestingly, the assembled electrode based on the as-prepared porous Mn2O3 microflowers proves to be a high-performance electrode material for supercapacitors. The electrode shows a specific capacitance of 994 F g-1, which can work well even after 4000 cycles at 0.75 A g-1. More importantly, the porous Mn2O3 microflowers and activated carbons are assembled into a high-performance flexible solid-state asymmetric supercapacitor with a specific capacitance of 312.5 mF cm-2. The cycle test shows that the device can offer 95.6% capacity of the initial capacitance at 2.0 mA cm-2 after 5000 cycles with little decay. The maximum energy density of the device can achieve 6.56 mWh cm-3 and the maximum power density can also achieve 283.5 mW cm-3, which are among the best results for manganese based materials.Dimanganese trioxide microflowers are easily obtained from a Mn(ii) 8-hydroxyquinoline microcoordination after calcination in air. We also look into the possible formation mechanism of the flower-like morphology, and find that the reaction time affects the morphology of the coordination. Furthermore, the as-prepared porous Mn2O3 microflowers are made of many nanoplates which form many nanogaps and nanochannels. Interestingly, the assembled electrode based on the as-prepared porous Mn2O3 microflowers proves to be a high-performance electrode material for supercapacitors. The electrode shows a specific capacitance of 994 F g-1, which can work well even after 4000 cycles at 0.75 A g-1. More importantly, the porous Mn2O3 microflowers and activated carbons are assembled into a high-performance flexible solid-state asymmetric supercapacitor with a specific capacitance of 312.5 mF cm-2. The cycle test shows that the device can offer 95.6% capacity of the initial capacitance at 2.0 mA cm-2 after 5000 cycles with little decay. The maximum energy density of the device can achieve 6.56 mWh cm-3 and the maximum power density can also achieve 283.5 mW cm-3, which are among the best results for manganese based materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02267g

Tetra-heteroatom self-doped carbon nanosheets derived from silkworm excrement for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Lei, Shuijin; Chen, Lianfu; Zhou, Wei; Deng, Peiqin; Liu, Yan; Fei, Linfeng; Lu, Wei; Xiao, Yanhe; Cheng, Baochang

2018-03-01

Carbon materials are deemed to be competitive candidate electrode materials for energy storage systems. It is still a great challenge to explore advanced carbon-based electrode materials for high-performance supercapacitors by a facile, economical and efficient method. In this work, N-, P-, S-, O-self-doped carbon nanosheets with high surface area and well-developed porosity are successfully prepared by pyrolysis carbonization and post KOH activation from silkworm excrement, a novel abundant, low-cost and eco-friendly agricultural waste. Thanks to their unique multi-heteroatom doping and porous structure, the obtained carbon materials exhibit high charge storage capacity with a specific capacitance of 401 F g-1 at a current density of 0.5 A g-1 in 6 M KOH and good cycling stability with a capacitance retention of 93.8% over 10000 cycles. A symmetric supercapacitor device using 1 M Na2SO4 aqueous solution as the electrolyte can deliver a specific capacitance of 41.7 F g-1 at a current density of 0.5 A g-1, and a high energy density of 23.17 Wh kg-1 at a power density of 500 W kg-1 with a wide voltage window of 2.0 V. This work develops a new strategy to produce favorable carbon-based electrode materials for supercapacitors with high electrochemical performances.

Biochar-based carbons with hierarchical micro-meso-macro porosity for high rate and long cycle life supercapacitors

NASA Astrophysics Data System (ADS)

Qiu, Zhipeng; Wang, Yesheng; Bi, Xu; Zhou, Tong; Zhou, Jin; Zhao, Jinping; Miao, Zhichao; Yi, Weiming; Fu, Peng; Zhuo, Shuping

2018-02-01

The development of supercapacitors with high energy density and power density is an important research topic despite many challenging issues exist. In this work, porous carbon material was prepared from corn straw biochar and used as the active electrode material for electric double-layer capacitors (EDLCs). During the KOH activation process, the ratio of KOH/biochar significantly affects the microstructure of the resultant carbon, which further influences the capacitive performance. The optimized carbon material possesses typical hierarchical porosity composed of multi-leveled pores with high surface area and pore volume up to 2790.4 m2 g-1 and 2.04 cm3 g-1, respectively. Such hierarchical micro-meso-macro porosity significantly improved the rate performance of the biochar-based carbons. The achieved maximum specific capacitance was 327 F g-1 and maintained a high value of 205 F g-1 at a ultrahigh current density of 100 A g-1. Meanwhile, the prepared EDLCs present excellent cycle stability in alkaline electrolytes for 120 000 cycles at 5 A g-1. Moreover, the biochar-based carbon could work at a high voltage of 1.6 V in neutral Na2SO4, and exhibit a high specific capacitance of 227 F g-1, thus giving an outstanding energy density of 20.2 Wh kg-1.

Significant Performance Enhancement in Asymmetric Supercapacitors based on Metal Oxides, Carbon nanotubes and Neutral Aqueous Electrolyte.

PubMed

Singh, Arvinder; Chandra, Amreesh

2015-10-23

Amongst the materials being investigated for supercapacitor electrodes, carbon based materials are most investigated. However, pure carbon materials suffer from inherent physical processes which limit the maximum specific energy and power that can be achieved in an energy storage device. Therefore, use of carbon-based composites with suitable nano-materials is attaining prominence. The synergistic effect between the pseudocapacitive nanomaterials (high specific energy) and carbon (high specific power) is expected to deliver the desired improvements. We report the fabrication of high capacitance asymmetric supercapacitor based on electrodes of composites of SnO2 and V2O5 with multiwall carbon nanotubes and neutral 0.5 M Li2SO4 aqueous electrolyte. The advantages of the fabricated asymmetric supercapacitors are compared with the results published in the literature. The widened operating voltage window is due to the higher over-potential of electrolyte decomposition and a large difference in the work functions of the used metal oxides. The charge balanced device returns the specific capacitance of ~198 F g(-1) with corresponding specific energy of ~89 Wh kg(-1) at 1 A g(-1). The proposed composite systems have shown great potential in fabricating high performance supercapacitors.

Polyaniline-coated freestanding porous carbon nanofibers as efficient hybrid electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Tran, Chau; Singhal, Richa; Lawrence, Daniel; Kalra, Vibha

2015-10-01

Three-dimensional, free-standing, hybrid supercapacitor electrodes combining polyaniline (PANI) and porous carbon nanofibers (P-CNFs) were fabricated with the aim to integrate the benefits of both electric double layer capacitors (high power, cyclability) and pseudocapacitors (high energy density). A systematic investigation of three different electropolymerization techniques, namely, potentiodynamic, potentiostatic, and galvanostatic, for electrodeposition of PANI on freestanding carbon nanofiber mats was conducted. It was found that the galvanostatic method, where the current density is kept constant and can be easily controlled facilitates conformal and uniform coating of PANI on three-dimensional carbon nanofiber substrates. The electrochemical tests indicated that the PANI-coated P-CNFs exhibit excellent specific capacitance of 366 F g-1 (vs. 140 F g-1 for uncoated porous carbon nanofibers), 140 F cm-3 volumetric capacitance, and up to 2.3 F cm-2 areal capacitance at 100 mV s-1 scan rate. Such excellent performance is attributed to a thin and conformal coating of PANI achieved using the galvanostatic electrodeposition technique, which not only provides pseudocapacitance with high rate capability, but also retains the double-layer capacitance of the underlying P-CNFs.

Biopolymer-nanocarbon composite electrodes for use as high-energy high-power density electrodes

NASA Astrophysics Data System (ADS)

Karakaya, Mehmet; Roberts, Mark; Arcilla-Velez, Margarita; Zhu, Jingyi; Podila, Ramakrishna; Rao, Apparao

2014-03-01

Supercapacitors (SCs) address our current energy storage and delivery needs by combining the high power, rapid switching, and exceptional cycle life of a capacitor with the high energy density of a battery. Although activated carbon is extensively used as a supercapacitor electrode due to its inexpensive nature, its low specific capacitance (100-120 F/g) fundamentally limits the energy density of SCs. We demonstrate that a nano-carbon based mechanically robust, electrically conducting, free-standing buckypaper electrode modified with an inexpensive biorenewable polymer, viz., lignin increases the electrode's specific capacitance (~ 600-700 F/g) while maintaining rapid discharge rates. In these systems, the carbon nanomaterials provide the high surface area, electrical conductivity and porosity, while the redox polymers provide a mechanism for charge storage through Faradaic charge transfer. The design of redox polymers and their incorporation into nanomaterial electrodes will be discussed with a focus on enabling high power and high energy density electrodes. Research supported by US NSF CMMI Grant 1246800.

Carbon nanotube balls and their application in supercapacitors.

PubMed

Kang, Da-Young; Moon, Jun Hyuk

2014-01-08

We have provided a design of the macroscopic morphology of carbon nanotubes (CNTs) using emulsion droplet confinement. The evaporation of CNT-dispersed aqueous emulsion droplets in oil produces spherical CNT assemblies, i.e., CNT balls. In this emulsion-assisted method, compact packing of CNT was obtained by the presence of capillary pressure during droplet evaporation. The size of the CNT balls could be controlled by changing the concentration of the CNT dispersion solution; typically, CNT balls with an average size in the range of 8-12 μm were obtained with a Brunauer-Emmett-Teller (BET) specific area of 200 m(2)/g. Heat treatment of the CNT balls, which was required to remove residual solvent, and cement CNTs was followed, and their effect has been characterized; the heat treatment at high temperature desorbed surface oxygenated groups of CNTs and created defective carbon structures, but did not change pore structure. The dispersion of CNT balls was applied to form CNT ball-assembled film for a supercapacitor electrode. The specific capacitance of 80 F/g was obtained at 500 °C heat treatment, but the CNT balls prepared at a higher temperature actually decreased the capacitance, because of the removal of surface oxygenated groups, thereby decreasing the pseudo-capacitance. The capacitive properties of CNT ball-assembled electrodes were compared to CNT films; the CNT ball electrodes showed 40% higher specific electrochemical capacitance and higher rate performance, which is attributed to the compact packing of CNTs in the CNT ball and the hierarchical porous structures in the ball assemblies.

ZnCo2O4-reduced graphene oxide composite with balanced capacitive performance in asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Gao, Zhiyong; Zhang, Lingcui; Chang, Jiuli; Wang, Zhen; Wu, Dapeng; Xu, Fang; Guo, Yuming; Jiang, Kai

2018-06-01

ZnCo2O4-rGO composite with intertwined sheets grown onto nickel foam substrate is prepared through a facile hydrothermal deposition and followed thermal annealing treatment, which can be directly employed as binder free electrode of supercapacitor. The hierarchically porous texture of ZnCo2O4-rGO composite with high specific surface area and efficient ions diffusion channels ensures sufficient faradic reaction of ZnCo2O4 component, therefore enables an ultrahigh electrode specific capacitance (Cs) of 3222 F g-1 at 1 A g-1 in alkali electrolyte, and the Cs still retains to be 860 F g-1 at 20 A g-1. When used as positive electrode of full cell, the ZnCo2O4-rGO//activated carbon (AC) asymmetric supercapacitor can offer a maximum device specific capacitance (Ccell) of 139 F g-1 at 0.5 A g-1 and therefore an energy density (Ecell) of 49.1 Wh kg-1 at power density (Pcell) of 400 W kg-1. Even at high Pcell of 7625 W kg-1, the Ecell of the asymmetric device can still retain to be 18.8 Wh kg-1. More significantly, the asymmetric supercapacitor demonstrates only 6% Ccell fade subjected to 5000 successive charge-discharge cycles. The balanced Ecell, Pcell delivery abilities and high cycleability highlight the potential of the faradic ZnCo2O4-rGO composite in high performance and long lifetime energy storage devices.

All-solid-state flexible supercapacitors based on highly dispersed polypyrrole nanowire and reduced graphene oxide composites.

PubMed

Yu, Chenfei; Ma, Peipei; Zhou, Xi; Wang, Anqi; Qian, Tao; Wu, Shishan; Chen, Qiang

2014-10-22

Highly dispersed polypyrrole nanowires are decorated on reduced graphene oxide sheets using a facile in situ synthesis route. The prepared composites exhibit high dispersibility, large effective surface area, and high electric conductivity. All-solid-state flexible supercapacitors are assembled based on the prepared composites, which show excellent electrochemical performances with a specific capacitance of 434.7 F g(-1) at a current density of 1 A g(-1). The as-fabricated supercapacitor also exhibits excellent cycling stability (88.1% capacitance retention after 5000 cycles) and exceptional mechanical flexibility. In addition, outstanding power and energy densities were obtained, demonstrating the significant potential of prepared material for flexible and portable energy storage devices.

Holey nickel hydroxide nanosheets for wearable solid-state fiber-supercapacitors.

PubMed

Shi, Peipei; Chen, Rong; Li, Li; An, Jianing; Hua, Li; Zhou, Jinyuan; Liu, Bin; Chen, Peng; Huang, Wei; Sun, Gengzhi

2018-03-28

Holey nickel hydroxide (Ni(OH) 2 ) nanosheets with a mean thickness of 2 nm are facilely synthesized, and then embedded in carbon nanotube (CNT) scaffolds to construct a hybrid fiber electrode, which shows a high volumetric capacitance of 335.9 F cm -3 at 0.8 A cm -3 and superior rate performance. The hybrid supercapacitor made from the Ni(OH) 2 /CNT fiber can deliver a high specific capacitance of 24.8 F cm -3 and an energy density of 5.8 mW h cm -3 with outstanding mechanical stability under repeated bending conditions.

Electrochemical capacitor

DOEpatents

Anderson, Marc A.; Liu, Kuo -Chuan; Mohr, Charles M.

1999-10-05

An inexpensive porous metal oxide material having high surface area, good conductivity and high specific capacitance is advantageously used in an electrochemical capacitor. The materials are formed in a sol-gel process which affords control over the properties of the resultant metal oxide materials.

The composite capacitive behaviors of the N and S dual doped ordered mesoporous carbon with ultrahigh doping level

NASA Astrophysics Data System (ADS)

Zhang, Deyi; Lei, Longyan; Shang, Yonghua; Wang, Kunjie; Wang, Yi

2016-01-01

Heteroatoms doping provides a promising strategy for improving the energy density of supercapacitors based on the carbon electrodes. In this paper, we present a N and S dual doped ordered mesoporous carbon with ultrahigh doping level using dimethylglyoxime as pristine precursor. The N doping content of the reported materials varies from 6.6 to 15.6 at.% dependent on the carbonization temperature, and the S doping content varies from 0.46 to 1.01 at.%. Due to the ultrahigh heteroatoms doping content, the reported materials exhibit pronounced pseudo-capacitance. Meanwhile, the reported materials exhibit high surface areas (640⿿869 m2 g⿿1), large pore volume (0.71⿿1.08 cm2 g⿿1) and ordered pore structure. The outstanding textual properties endow the reported materials excellent electrical double-layer capacitance (EDLC). By effectively combining the pseudo-capacitance with EDLC, the reported materials exhibit a surprising energy storage/relax capacity with the highest specific capacitance of 565 F g⿿1, which value is 3.3 times higher than that of pristine CMK-3, and can compete against some conventional pseudo-capacitance materials.

Simple synthesis of amorphous NiWO4 nanostructure and its application as a novel cathode material for asymmetric supercapacitors.

PubMed

Niu, Lengyuan; Li, Zhangpeng; Xu, Ye; Sun, Jinfeng; Hong, Wei; Liu, Xiaohong; Wang, Jinqing; Yang, Shengrong

2013-08-28

This study reports a simple synthesis of amorphous nickel tungstate (NiWO4) nanostructure and its application as a novel cathode material for supercapacitors. The effect of reaction temperature on the electrochemical properties of the NiWO4 electrode was studied, and results demonstrate that the material synthesized at 70 °C (NiW-70) has shown the highest specific capacitance of 586.2 F g(-1) at 0.5 A g(-1) in a three-electrode system. To achieve a high energy density, a NiW-70//activated carbon asymmetric supercapacitor is successfully assembled by use of NiW-70 and activated carbon as the cathode and anode, respectively, and then, its electrochemical performance is characterized by cyclic voltammetry and galvanostatic charge-discharge measurements. The results show that the assembled asymmetric supercapacitor can be cycled reversibly between 0 and 1.6 V with a high specific capacitance of 71.1 F g(-1) at 0.25 A g(-1), which can deliver a maximum energy density of 25.3 Wh kg(-1) at a power density of 200 W kg(-1). Furthermore, this asymmetric supercapacitor also presented an excellent, long cycle life along with 91.4% specific capacitance being retained after 5000 consecutive times of cycling.

Ultra-light Hierarchical Graphene Electrode for Binder-Free Supercapacitors and Lithium-Ion Battery Anodes.

PubMed

Zuo, Zicheng; Kim, Tae Young; Kholmanov, Iskandar; Li, Huifeng; Chou, Harry; Li, Yuliang

2015-10-07

A mild and environmental-friendly method is developed for fabricating a 3D interconnected graphene electrode with large-scale continuity. Such material has interlayer pores between reduced graphene oxide nanosheets and in-plane pores. Hence, a specific surface area up to 835 m(2) g(-1) and a high powder conductivity up to 400 S m(-1) are achieved. For electrochemical applications, the interlayer pores can serve as "ion-buffering reservoirs" while in-plane ones act as "channels" for shortening the mass cross-plane diffusion length, reducing the ion response time, and prevent the interlayer restacking. As binder-free supercapacitor electrode, it delivers a specific capacitance up to 169 F g(-1) with surface-normalized capacitance close to 21 μF cm(-2) (intrinsic capacitance) and power density up to 7.5 kW kg(-1), in 6 m KOH aqueous electrolyte. In the case of lithium-ion battery anode, it shows remarkable advantages in terms of the initiate reversible Coulombic efficiency (61.3%), high specific capacity (932 mAh g(-1) at 100 mA g(-1)), and robust long-term retention (93.5% after 600 cycles at 2000 mAh g(-1)). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Construction of Core-Shell NiMoO4@Ni-Co-S Nanorods as Advanced Electrodes for High-Performance Asymmetric Supercapacitors.

PubMed

Chen, Chao; Yan, Dan; Luo, Xin; Gao, Wenjia; Huang, Guanjie; Han, Ziwu; Zeng, Yan; Zhu, Zhihong

2018-02-07

In this work, hierarchical core-shell NiMoO 4 @Ni-Co-S nanorods were first successfully grown on nickel foam by a facile two-step method to fabricate a bind-free electrode. The well-aligned electrode wrapped by Ni-Co-S nanosheets displays excellent nanostructural properties and outstanding electrochemical performance, owing to the synergistic effects of both nickel molybdenum oxides and nickel cobalt sulfides. The prepared core-shell nanorods in a three-electrode cell yielded a high specific capacitance of 2.27 F cm -2 (1892 F g -1 ) at a current density of 5 mA cm -2 and retained 91.7% of the specific capacitance even after 6000 cycles. Their electrochemical performance was further investigated for their use as positive electrode for asymmetric supercapacitors. Notably, the energy density of the asymmetric supercapacitor device reached 2.45 mWh cm -3 at a power density of 0.131 W cm -3 , and still retained a remarkable 80.3% of the specific capacitance after 3500 cycles. There is great potential for the electrode composed of the core-shell NiMoO 4 @Ni-Co-S nanorods for use in an all-solid-state asymmetric supercapacitor device.

Novel designs for application specific MEMS pressure sensors.

PubMed

Fragiacomo, Giulio; Reck, Kasper; Lorenzen, Lasse; Thomsen, Erik V

2010-01-01

In the framework of developing innovative microfabricated pressure sensors, we present here three designs based on different readout principles, each one tailored for a specific application. A touch mode capacitive pressure sensor with high sensitivity (14 pF/bar), low temperature dependence and high capacitive output signal (more than 100 pF) is depicted. An optical pressure sensor intrinsically immune to electromagnetic interference, with large pressure range (0-350 bar) and a sensitivity of 1 pm/bar is presented. Finally, a resonating wireless pressure sensor power source free with a sensitivity of 650 KHz/mmHg is described. These sensors will be related with their applications in harsh environment, distributed systems and medical environment, respectively. For many aspects, commercially available sensors, which in vast majority are piezoresistive, are not suited for the applications proposed.

Crosslinked Carbon Nanotubes/Polyaniline Composites as a Pseudocapacitive Material with High Cycling Stability

PubMed Central

Liu, Dong; Wang, Xue; Deng, Jinxing; Zhou, Chenglong; Guo, Jinshan; Liu, Peng

2015-01-01

The poor cycling stability of polyaniline (PANI) limits its practical application as a pseudocapacitive material due to the volume change during the charge-discharge procedure. Herein, crosslinked carbon nanotubes/polyaniline (C-CNTs/PANI) composites had been designed by the in situ chemical oxidative polymerization of aniline in the presence of crosslinked carbon nanotubes (C-CNTs), which were obtained by coupling of the functionalized carbon nanotubes with 1,4-benzoquinone. The composite showed a specific capacitance of 294 F/g at the scan rate of 10 mV/s, and could retain 95% of its initial specific capacitance after 1000 CV cycles. Such high electrochemical cycling stability resulting from the crosslinked skeleton of the C-CNTs makes them potential electrode materials for a supercapacitor. PMID:28347050

A facile one-step approach for the fabrication of polypyrrole nanowire/carbon fiber hybrid electrodes for flexible high performance solid-state supercapacitors

NASA Astrophysics Data System (ADS)

Huang, Sanqing; Han, Yichuan; Lyu, Siwei; Lin, Wenzhen; Chen, Peishan; Fang, Shaoli

2017-10-01

Wearable electronics are in high demand, requiring that all the components are flexible. Here we report a facile approach for the fabrication of flexible polypyrrole nanowire (NPPy)/carbon fiber (CF) hybrid electrodes with high electrochemical activity using a low-cost, one-step electrodeposition method. The structure of the NPPy/CF electrodes can be easily controlled by the applied electrical potential and electrodeposition time. Our NPPy/CF-based electrodes showed high flexibility, conductivity, and stability, making them ideal for flexible all-solid-state fiber supercapacitors. The resulting NPPy/CF-based supercapacitors provided a high specific capacitance of 148.4 F g-1 at 0.128 A g-1, which is much higher than for supercapacitors based on polypyrrole film/CF (38.3 F g-1) and pure CF (0.6 F g-1) under the same conditions. The NPPy/CF-based supercapacitors also showed high bending and cycling stability, retaining 84% of the initial capacitance after 500 bending cycles, and 91% of the initial capacitance after 5000 charge/discharge cycles.

A facile one-step approach for the fabrication of polypyrrole nanowire/carbon fiber hybrid electrodes for flexible high performance solid-state supercapacitors.

PubMed

Huang, Sanqing; Han, Yichuan; Lyu, Siwei; Lin, Wenzhen; Chen, Peishan; Fang, Shaoli

2017-10-27

Wearable electronics are in high demand, requiring that all the components are flexible. Here we report a facile approach for the fabrication of flexible polypyrrole nanowire (NPPy)/carbon fiber (CF) hybrid electrodes with high electrochemical activity using a low-cost, one-step electrodeposition method. The structure of the NPPy/CF electrodes can be easily controlled by the applied electrical potential and electrodeposition time. Our NPPy/CF-based electrodes showed high flexibility, conductivity, and stability, making them ideal for flexible all-solid-state fiber supercapacitors. The resulting NPPy/CF-based supercapacitors provided a high specific capacitance of 148.4 F g -1 at 0.128 A g -1 , which is much higher than for supercapacitors based on polypyrrole film/CF (38.3 F g -1 ) and pure CF (0.6 F g -1 ) under the same conditions. The NPPy/CF-based supercapacitors also showed high bending and cycling stability, retaining 84% of the initial capacitance after 500 bending cycles, and 91% of the initial capacitance after 5000 charge/discharge cycles.

3D polyaniline porous layer anchored pillared graphene sheets: enhanced interface joined with high conductivity for better charge storage applications.

PubMed

Sekar, Pandiaraj; Anothumakkool, Bihag; Kurungot, Sreekumar

2015-04-15

Here, we report synthesis of a 3-dimensional (3D) porous polyaniline (PANI) anchored on pillared graphene (G-PANI-PA) as an efficient charge storage material for supercapacitor applications. Benzoic acid (BA) anchored graphene, having spatially separated graphene layers (G-Bz-COOH), was used as a structure controlling support whereas 3D PANI growth has been achieved by a simple chemical oxidation of aniline in the presence of phytic acid (PA). The BA groups on G-Bz-COOH play a critical role in preventing the restacking of graphene to achieve a high surface area of 472 m(2)/g compared to reduced graphene oxide (RGO, 290 m(2)/g). The carboxylic acid (-COOH) group controls the rate of polymerization to achieve a compact polymer structure with micropores whereas the chelating nature of PA plays a crucial role to achieve the 3D growth pattern of PANI. This type of controlled interplay helps G-PANI-PA to achieve a high conductivity of 3.74 S/cm all the while maintaining a high surface area of 330 m(2)/g compared to PANI-PA (0.4 S/cm and 60 m(2)/g). G-PANI-PA thus conceives the characteristics required for facile charge mobility during fast charge-discharge cycles, which results in a high specific capacitance of 652 F/g for the composite. Owing to the high surface area along with high conductivity, G-PANI-PA displays a stable specific capacitance of 547 F/g even with a high mass loading of 3 mg/cm(2), an enhanced areal capacitance of 1.52 F/cm(2), and a volumetric capacitance of 122 F/cm(3). The reduced charge-transfer resistance (RCT) of 0.67 Ω displayed by G-PANI-PA compared to pure PANI (0.79 Ω) stands out as valid evidence of the improved charge mobility achieved by the system by growing the 3D PANI layer along the spatially separated layers of the graphene sheets. The low RCT helps the system to display capacitance retention as high as 65% even under a high current dragging condition of 10 A/g. High charge/discharge rates and good cycling stability are the other highlights of the supercapacitor system derived from this composite material.

Electrodeposition and Capacitive Behavior of Films for Electrodes of Electrochemical Supercapacitors

NASA Astrophysics Data System (ADS)

Shi, C.; Zhitomirsky, I.

2010-03-01

Polypyrrole films were deposited by anodic electropolymerization on stainless steel substrates from aqueous pyrrole solutions containing sodium salicylate and tiron additives. The deposition yield was studied under galvanostatic conditions. The amount of the deposited material was varied by the variation of deposition time at a constant current density. SEM studies showed the formation of porous films with thicknesses in the range of 0-3 μm. Cyclic voltammetry data for the films tested in 0.5 M Na2SO4 solutions showed capacitive behavior and high specific capacitance (SC) in a voltage window of 0.9 V. The films prepared from pyrrole solutions containing tiron showed better capacitive behavior compared to the films prepared from the solutions containing sodium salicylate. A highest SC of 254 F g-1 was observed for the sample with a specific mass of 89 μg cm-2 at a scan rate of 2 mV s-1. The SC decreased with an increasing film thickness and scan rate. The results indicated that the polypyrrole films deposited on the stainless steel substrates by anodic electropolymerization can be used as electrodes for electrochemical supercapacitors (ES).

Electrodeposition and capacitive behavior of films for electrodes of electrochemical supercapacitors.

PubMed

Shi, C; Zhitomirsky, I

2010-01-08

Polypyrrole films were deposited by anodic electropolymerization on stainless steel substrates from aqueous pyrrole solutions containing sodium salicylate and tiron additives. The deposition yield was studied under galvanostatic conditions. The amount of the deposited material was varied by the variation of deposition time at a constant current density. SEM studies showed the formation of porous films with thicknesses in the range of 0-3 μm. Cyclic voltammetry data for the films tested in 0.5 M Na2SO4 solutions showed capacitive behavior and high specific capacitance (SC) in a voltage window of 0.9 V. The films prepared from pyrrole solutions containing tiron showed better capacitive behavior compared to the films prepared from the solutions containing sodium salicylate. A highest SC of 254 F g-1 was observed for the sample with a specific mass of 89 μg cm-2 at a scan rate of 2 mV s-1. The SC decreased with an increasing film thickness and scan rate. The results indicated that the polypyrrole films deposited on the stainless steel substrates by anodic electropolymerization can be used as electrodes for electrochemical supercapacitors (ES).

Electrodeposition and Capacitive Behavior of Films for Electrodes of Electrochemical Supercapacitors

PubMed Central

2010-01-01

Polypyrrole films were deposited by anodic electropolymerization on stainless steel substrates from aqueous pyrrole solutions containing sodium salicylate and tiron additives. The deposition yield was studied under galvanostatic conditions. The amount of the deposited material was varied by the variation of deposition time at a constant current density. SEM studies showed the formation of porous films with thicknesses in the range of 0–3 μm. Cyclic voltammetry data for the films tested in 0.5 M Na2SO4 solutions showed capacitive behavior and high specific capacitance (SC) in a voltage window of 0.9 V. The films prepared from pyrrole solutions containing tiron showed better capacitive behavior compared to the films prepared from the solutions containing sodium salicylate. A highest SC of 254 F g−1 was observed for the sample with a specific mass of 89 μg cm−2 at a scan rate of 2 mV s−1. The SC decreased with an increasing film thickness and scan rate. The results indicated that the polypyrrole films deposited on the stainless steel substrates by anodic electropolymerization can be used as electrodes for electrochemical supercapacitors (ES). PMID:20672082

Nanostructure selenium compounds as pseudocapacitive electrodes for high-performance asymmetric supercapacitor

PubMed Central

Hua, Fengting; Sun, Kanjun; Fenga, Enke; Peng, Hui; Zhang, Zhiguo; Lei, Ziqiang

2018-01-01

The electrochemical performance of an energy conversion and storage device like the supercapacitor mainly depends on the microstructure and morphology of the electrodes. In this paper, to improve the capacitance performance of the supercapacitor, the all-pseudocapacitive electrodes of lamella-like Bi18SeO29/BiSe as the negative electrode and flower-like Co0.85Se nanosheets as the positive electrode are synthesized by using a facile low-temperature one-step hydrothermal method. The microstructures and morphology of the electrode materials are carefully characterized, and the capacitance performances are also tested. The Bi18SeO29/BiSe and Co0.85Se have high specific capacitance (471.3 F g–1 and 255 F g–1 at 0.5 A g–1), high conductivity, outstanding cycling stability, as well as good rate capability. The assembled asymmetric supercapacitor completely based on the pseudocapacitive electrodes exhibits outstanding cycling stability (about 93% capacitance retention after 5000 cycles). Moreover, the devices exhibit high energy density of 24.2 Wh kg–1 at a power density of 871.2 W kg–1 in the voltage window of 0–1.6 V with 2 M KOH solution. PMID:29410830

Oxygen-Vacancy Abundant Ultrafine Co3O4/Graphene Composites for High-Rate Supercapacitor Electrodes.

PubMed

Yang, Shuhua; Liu, Yuanyue; Hao, Yufeng; Yang, Xiaopeng; Goddard, William A; Zhang, Xiao Li; Cao, Bingqiang

2018-04-01

The metal oxides/graphene composites are one of the most promising supercapacitors (SCs) electrode materials. However, rational synthesis of such electrode materials with controllable conductivity and electrochemical activity is the topical challenge for high-performance SCs. Here, the Co 3 O 4 /graphene composite is taken as a typical example and develops a novel/universal one-step laser irradiation method that overcomes all these challenges and obtains the oxygen-vacancy abundant ultrafine Co 3 O 4 nanoparticles/graphene (UCNG) composites with high SCs performance. First-principles calculations show that the surface oxygen vacancies can facilitate the electrochemical charge transfer by creating midgap electronic states. The specific capacitance of the UCNG electrode reaches 978.1 F g -1 (135.8 mA h g -1 ) at the current densities of 1 A g -1 and retains a high capacitance retention of 916.5 F g -1 (127.3 mA h g -1 ) even at current density up to 10 A g -1 , showing remarkable rate capability (more than 93.7% capacitance retention). Additionally, 99.3% of the initial capacitance is maintained after consecutive 20 000 cycles, demonstrating enhanced cycling stability. Moreover, this proposed laser-assisted growth strategy is demonstrated to be universal for other metal oxide/graphene composites with tuned electrical conductivity and electrochemical activity.

Carbon nanotube network film directly grown on carbon cloth for high-performance solid-state flexible supercapacitors

NASA Astrophysics Data System (ADS)

Zhou, Cheng; Liu, Jinping

2014-01-01

Carbon nanotubes (CNTs) have received increasing attention as electrode materials for high-performance supercapacitors. We herein present a straightforward method to synthesize CNT films directly on carbon cloths as electrodes for all-solid-state flexible supercapacitors (AFSCs). The as-made highly conductive electrodes possess a three-dimensional (3D) network architecture for fast ion diffusion and good flexibility, leading to an AFSC with a specific capacitance of 106.1 F g-1, an areal capacitance of 38.75 mF cm-2, an ultralong cycle life of 100 000 times (capacitance retention: 99%), a good rate capability (can scan at 1000 mV s-1, at which the capacitance is still ˜37.8% of that at 5 mV s-1), a high energy density (2.4 μW h cm-2) and a high power density (19 mW cm-2). Moreover, our AFSC maintains excellent electrochemical attributes even with serious shape deformation (bending, folding, etc), high mechanical pressure (63 kPa) and a wide temperature window (up to 100 ° C). After charging for only 5 s, three such AFSC devices connected in series can efficiently power a red round LED for 60 s. Our work could pave the way for the design of practical AFSCs, which are expected to be used for various flexible portable/wearable electronic devices in the future.

Effects of CO{sub 2} activation on electrochemical performance of microporous carbons derived from poly(vinylidene fluoride)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Seul-Yi; Park, Soo-Jin, E-mail: sjpark@inha.ac.kr

In this work, we have prepared microporous carbons (MPCs) derived from poly(vinylidene fluoride) (PVDF), and the physical activation of MPCs using CO{sub 2} gas is subsequently carried out with various activation temperatures to investigate the electrochemical performance. PVDF is successfully converted into MPCs with a high specific surface area and well-developed micropores. After CO{sub 2} activation, the specific surface areas of MPCs (CA-MPCs) are enhanced by 12% compared with non-activated MPCs. With increasing activation temperature, the micropore size distributions of A-MPCs also become narrower and shift to larger pore size. It is also confirmed that the CO{sub 2} activation hadmore » developed the micropores and introduced the oxygen-containing groups to MPCs′ surfaces. From the results, the specific capacitances of the electrodes in electric double layer capacitors (EDLCs) based on CA-MPCs are distinctly improved through CO{sub 2} activation. The highest specific capacitance of the A-MPCs activated at 700 °C is about 125 F/g, an enhancement of 74% in comparison with NA-MPCs, at a discharge current of 2 A/g in a 6 M KOH electrolyte solution. We also found that micropore size of 0.67 nm has a specific impact on the capacitance behaviors, besides the specific surface area of the electrode samples. - Graphical abstract: The A-MPC samples with high specific surface area (ranging from 1030 to 1082 m{sup 2}/g), corresponding to micropore sizes of 0.67 and 0.72 nm, and with the amount of oxygen-containing groups ranging from 3.2% to 4.4% have been evaluated as electrodes for EDLC applications. . Display Omitted - Highlights: • Microporous carbons (MPCs) were synthesized without activation process. • Next, we carried out the CO{sub 2} activation of MPCs with activation temperatures. • It had developed the micropores and introduced the O-functional groups to MPCs. • The highest specific capacitance: 125 F/g, an increase of 74% compared to MPCs.« less

Electrodes of carbonized MWCNT-cellulose paper for supercapacitor

NASA Astrophysics Data System (ADS)

Sun, Xiaogang; Cai, Manyuan; Chen, Long; Qiu, Zhiwen; Liu, Zhenghong

2017-07-01

A flexible composite paper of multi-walled carbon nanotube (MWCNT) and cellulose fiber (CF) were fabricated by traditional paper-making method. Then, the MWCNT/CF papers were carbonized at high temperature in vacuum to remove organic component. The carbonized MWCNT/CF (MWCNT/CCF) papers are consisted of MWCNT and carbon fiber. The papers were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and four-point probe resistance meter. The electrochemical performances of the supercapacitors were tested by cyclic voltammetry and galvanostatic charge/discharge >with 1 moL/L LiPF6 as electrolyte. The MWCNT/CCF electrode yielded a specific capacitance of 156F/g at a current density of 50 mA/g by galvanostatic charge/discharge measurement, which is 1.29 times higher than MWCNT/CF electrode of 68F/g. The MWCNT/CCF electrodes also displayed an excellent specific capacitance retention of 84% after 2000 continuous charge/discharge cycles at a current density of 400 mA/g. The increase of specific capacitance can be attributed to enhanced electrical conductivity of MWCNT/CCF papers and improved contact interface between electrolyte and electrodes.

Supercapacitive behaviors and their temperature dependence of sol-gel synthesized nanostructured manganese dioxide in lithium hydroxide electrolyte

NASA Astrophysics Data System (ADS)

Wang, Xiuling; Yuan, Anbao; Wang, Yuqin

In the present work, a nanostructured manganese dioxide material was synthesized by a sol-gel method starting with manganese acetate (MnAc 2·4H 2O) and citric acid (C 6H 8O 7·H 2O) raw materials, and characterized by X-ray diffraction, infrared spectroscopic and transmission electron microscope techniques. The electrochemical properties and the influence of temperature on supercapacitive behaviors of the nano-MnO 2 electrode in 1 M LiOH electrolyte were investigated using electrochemical methods. Experimental results show that the MnO 2 electrode can exhibit an excellent pseudocapacitive behavior in 1 M LiOH electrolyte, and a high specific capacitance of 317 F g -1 can be obtained at a charge/discharge current rate of 100 mA g -1 and at the temperature of 25 °C. We found that temperature has a crucial influence on the discharge specific capacitance of the electrode. The specific capacitance at 25 °C is higher than that at 15 or 35 °C.

Ultrathin two-dimensional MnO2/graphene hybrid nanostructures for high-performance, flexible planar supercapacitors.

PubMed

Peng, Lele; Peng, Xu; Liu, Borui; Wu, Changzheng; Xie, Yi; Yu, Guihua

2013-05-08

Planar supercapacitors have recently attracted much attention owing to their unique and advantageous design for 2D nanomaterials based energy storage devices. However, improving the electrochemical performance of planar supercapacitors still remains a great challenge. Here we report for the first time a novel, high-performance in-plane supercapacitor based on hybrid nanostructures of quasi-2D ultrathin MnO2/graphene nanosheets. Specifically, the planar structures based on the δ-MnO2 nanosheets integrated on graphene sheets not only introduce more electrochemically active surfaces for absorption/desorption of electrolyte ions, but also bring additional interfaces at the hybridized interlayer areas to facilitate charge transport during charging/discharging processes. The unique structural design for planar supercapacitors enables great performance enhancements compared to graphene-only devices, exhibiting high specific capacitances of 267 F/g at current density of 0.2 A/g and 208 F/g at 10 A/g and excellent rate capability and cycling stability with capacitance retention of 92% after 7000 charge/discharge cycles. Moreover, the high planar malleability of planar supercapacitors makes possible superior flexibility and robust cyclability, yielding capacitance retention over 90% after 1000 times of folding/unfolding. Ultrathin 2D nanomaterials represent a promising material platform to realize highly flexible planar energy storage devices as the power back-ups for stretchable/flexible electronic devices.

Direct growth of vanadium nitride nanosheets on carbon nanotube fibers as novel negative electrodes for high-energy-density wearable fiber-shaped asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Guo, Jiabin; Zhang, Qichong; Sun, Juan; Li, Chaowei; Zhao, Jingxin; Zhou, Zhenyu; He, Bing; Wang, Xiaona; Man, Ping; Li, Qiulong; Zhang, Jun; Xie, Liyan; Li, Mingxing; Yao, Yagang

2018-04-01

Significant efforts have been recently devoted to constructing high-performance fiber-shaped asymmetric supercapacitors. However, it is still a paramount challenge to develop high-energy-density fiber-shaped asymmetric supercapacitors for practical applications in portable and wearable electronics. This work reports a simple and efficient method to directly grow vanadium nitride nanosheets on carbon nanotube fibers as advanced negative electrodes with a high specific capacitance of 188 F/cm3 (564 mF/cm2). Taking advantage of their attractive structure, we successfully fabricated a fiber-shaped asymmetric supercapacitor device with a maximum operating voltage of 1.6 V by assembling the vanadium nitride/carbon nanotube fiber negative electrode with the Zinc-Nickel-Cobalt ternary oxides nanowire arrays positive electrode. Due to the excellent synergistic effects between positive and negative electrodes, a remarkable specific capacitance of 50 F/cm3 (150 mF/cm2) and an outstanding energy density of 17.78 mWh/cm3 (53.33 μWh/cm2) for our fiber-shaped asymmetric supercapacitor can be achieved. Furthermore, the as-assembled fiber-shaped asymmetric supercapacitor device has excellent mechanical flexibility in that 91% of the capacitance retained after bending 90° for 3000 times. Thus, this work exploits a pathway to construct high-energy-density fiber-shaped asymmetric supercapacitor for next-generation portable and wearable electronics.

High-performance supercapacitor based on three-dimensional flower-shaped Li4Ti5O12-graphene hybrid and pine needles derived honeycomb carbon.

PubMed

Xing, Ling-Li; Wu, Xu; Huang, Ke-Jing

2018-06-05

A three-dimensional (3D) flower-shaped Li 4 Ti 5 O 12 -graphene (Gr) hybrid micro/nanostructures and pine needles derived carbon nanopores (PNDCN) has been prepared by using the effective hydrothermal process. Due to the unique micro/nanostructures which can provide abundant surface active sites, the obtained 3D Li 4 Ti 5 O 12 -Gr displays a high specific capacitance of 706.52 F g -1 at 1 A g -1 . The prepared PNDCN also exhibits high specific capacitance of 314.50 F g -1 at 1 A g -1 benefiting from its interconnected honeycomb-like hierarchical and open structure, which facilitates the diffusion and reaction of electrolyte ions and enables an isotropic charging/discharging process. An asymmetric supercapacitor utilizing Li 4 Ti 5 O 12 -Gr as positive electrode and PNDCN as negative electrode has been fabricated, it delivers a high energy density of 35.06 Wh kg -1 at power density of 800.08 W kg -1 and outstanding cycling stability with 90.18% capacitance retention after 2000 cycles. The fabrication process presented in this work is facile, cost-effective, and environmentally benign, offering a feasible solution for manufacturing next-generation high-performance energy storage devices. Copyright © 2018. Published by Elsevier Inc.

Flexible and freestanding supercapacitor based on nanostructured poly(m-aminophenol)/carbon nanofiber hybrid mats with high energy and power densities

NASA Astrophysics Data System (ADS)

Choudhury, Arup; Dey, Baban; Sinha Mahapatra, Susanta; Kim, Doo-Won; Yang, Kap-Seung; Yang, Duck-Joo

2018-04-01

Nanostructured poly(m-aminophenol) (PmAP) coated freestanding carbon nanofiber (CNF) mats were fabricated through simple in situ rapid-mixing polymerization of m-aminophenol in the presence of a CNF mat for flexible solid-state supercapacitors. The surface compositions, morphology and pore structure of the hybrid mats were characterized by using various techniques, e.g., FTIR, Raman, XRD, FE-SEM, TEM, and N2 absorption. The results show that the PmAP nanoparticles were homogeneously deposited on CNF surfaces and formed a thin flexible hybrid mat, which were directly used to made electrodes for electrochemical analysis without using any binders or conductive additives. The electrochemical performances of the hybrid mats were easily tailored by varying the PmAP loading on a hybrid electrode. The PmAP/CNF-10 hybrid electrode with a relatively low PmAP loading (> 42 wt%) showed a high specific capacitance of 325.8 F g-1 and a volumetric capacitance of 273.6 F cm-3 at a current density of 0.5 A g-1, together with a specific capacitance retention of 196.2 F g-1 at 20 A g-1. The PmAP/CNF-10 hybrid electrode showed good cycling stability with 88.2% capacitance retention after 5000 cycles. A maximum energy density of 45.2 Wh kg-1 and power density of 20.4 kW kg-1 were achieved for the PmAP/CNF-10 hybrid electrode. This facile and cost-effective synthesis of a flexible binder-free PmAP/CNF hybrid mat with excellent capacitive performances encourages its possible commercial exploitation.

Mesopore- and Macropore-Dominant Nitrogen-Doped Hierarchically Porous Carbons for High-Energy and Ultrafast Supercapacitors in Non-Aqueous Electrolytes.

PubMed

Shao, Rong; Niu, Jin; Liang, Jingjing; Liu, Mengyue; Zhang, Zhengping; Dou, Meiling; Huang, Yaqin; Wang, Feng

2017-12-13

Non-aqueous electrolytes (e.g., organic and ionic liquid electrolytes) can undergo high working voltage to improve the energy densities of supercapacitors. However, the large ion sizes, high viscosities, and low ionic conductivities of organic and ionic liquid electrolytes tend to cause the low specific capacitances, poor rate, and cycling performance of supercapacitors based on conventional micropore-dominant activated carbon electrodes, limiting their practical applications. Herein, we propose an effective strategy to simultaneously obtain high power and energy densities in non-aqueous electrolytes via using a cattle bone-derived porous carbon as an electrode material. Because of the unique co-activation of KOH and hydroxyapatite (HA) within the cattle bone, nitrogen-doped hierarchically porous carbon (referred to as NHPC-HA/KOH) is obtained and possesses a mesopore- and macropore-dominant porosity with an ultrahigh specific surface area (2203 m 2 g -1 ) of meso- and macropores. The NHPC-HA/KOH electrodes exhibit superior performance with specific capacitances of 224 and 240 F g -1 at 5 A g -1 in 1.0 M TEABF 4 /AN and neat EMIMBF 4 electrolyte, respectively. The symmetric supercapacitor using NHPC-HA/KOH electrodes can deliver integrated high energy and power properties (48.6 W h kg -1 at 3.13 kW kg -1 in 1.0 M TEABF 4 /AN and 75 W h kg -1 at 3.75 kW kg -1 in neat EMIMBF 4 ), as well as superior cycling performance (over 89% of the initial capacitance after 10 000 cycles at 10 A g -1 ).

Great improvement in pseudocapacitor properties of nickel hydroxide via simple gold deposition

NASA Astrophysics Data System (ADS)

Kim, Sun-I.; Thiyagarajan, Pradheep; Jang, Ji-Hyun

2014-09-01

In this letter, we report a facile approach to improve the capacitor properties of nickel hydroxide (Ni(OH)2) by simply coating gold nanoparticles (Au NPs) on the surface of Ni(OH)2. Au NP-deposited Ni(OH)2 (Au/Ni(OH)2) has been prepared by application of a conventional colloidal coating of Au NPs on the surface of 3D-Ni(OH)2 synthesized via a hydrothermal method. Compared with pristine Ni(OH)2, Au/Ni(OH)2 shows a 41% enhanced capacitance value, excellent rate capacitance behavior at high current density conditions, and greatly improved cycling stability for supercapacitor applications. The specific capacitance of Au/Ni(OH)2 reached 1927 F g-1 at 1 A g-1, which is close to the theoretical capacitance and retained 66% and 80% of the maximum value at a high current density of 20 A g-1 and 5000 cycles while that of pristine Ni(OH)2 was 1363 F g-1 and significantly decreased to 48% and 30%, respectively, under the same conditions. The outstanding performance of Au/Ni(OH)2 as a supercapacitor is attributed to the presence of metal Au NPs on the surface of semiconductor Ni(OH)2; this permits the creation of virtual 3D conducting networks via metal/semiconductor contact, which induces fast electron and ion transport by acting as a bridge between Ni(OH)2 nanostructures, thus eventually leading to significantly improved electrochemical capacitive behaviors, as confirmed by the EIS and I-V characteristic data.In this letter, we report a facile approach to improve the capacitor properties of nickel hydroxide (Ni(OH)2) by simply coating gold nanoparticles (Au NPs) on the surface of Ni(OH)2. Au NP-deposited Ni(OH)2 (Au/Ni(OH)2) has been prepared by application of a conventional colloidal coating of Au NPs on the surface of 3D-Ni(OH)2 synthesized via a hydrothermal method. Compared with pristine Ni(OH)2, Au/Ni(OH)2 shows a 41% enhanced capacitance value, excellent rate capacitance behavior at high current density conditions, and greatly improved cycling stability for supercapacitor applications. The specific capacitance of Au/Ni(OH)2 reached 1927 F g-1 at 1 A g-1, which is close to the theoretical capacitance and retained 66% and 80% of the maximum value at a high current density of 20 A g-1 and 5000 cycles while that of pristine Ni(OH)2 was 1363 F g-1 and significantly decreased to 48% and 30%, respectively, under the same conditions. The outstanding performance of Au/Ni(OH)2 as a supercapacitor is attributed to the presence of metal Au NPs on the surface of semiconductor Ni(OH)2; this permits the creation of virtual 3D conducting networks via metal/semiconductor contact, which induces fast electron and ion transport by acting as a bridge between Ni(OH)2 nanostructures, thus eventually leading to significantly improved electrochemical capacitive behaviors, as confirmed by the EIS and I-V characteristic data. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02204a

Aqueous solutions of acidic ionic liquids for enhanced stability of polyoxometalate-carbon supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Hu, Chenchen; Zhao, Enbo; Nitta, Naoki; Magasinski, Alexandre; Berdichevsky, Gene; Yushin, Gleb

2016-09-01

Nanocomposites based on polyoxometalates (POMs) nanoconfined in microporous carbons have been synthesized and used as electrodes for supercapacitors. The addition of the pseudocapacitance from highly reversible redox reaction of POMs to the electric double-layer capacitance of carbon lead to an increase in specific capacitance of ∼90% at 1 mV s-1. However, high solubility of POM in traditional aqueous electrolytes leads to rapid capacity fading. Here we demonstrate that the use of aqueous solutions of protic ionic liquids (P-IL) as electrolyte instead of aqueous sulfuric acid solutions offers an opportunity to significantly improve POM cycling stability. Virtually no degradation in capacitance was observed in POM-based positive electrode after 10,000 cycles in an asymmetric capacitor with P-IL aqueous electrolyte. As such, POM-based carbon composites may now present a viable solution for enhancing energy density of electrical double layer capacitors (EDLC) based on pure carbon electrodes.

In-situ space-confined catalysis for fabricating 3D mesoporous graphene and their capacitive properties

NASA Astrophysics Data System (ADS)

Qin, Jian; Zhu, Shan; Feng, Chao; Zhao, Naiqin; Shi, Chunsheng; Liu, En-Zuo; He, Fang; Ma, Liying; Li, Jiajun; He, Chunnian

2018-03-01

A one-step strategy for preparing 3D mesoporous graphene networks (3DMGNs) based on the concepts of space-confined effect, catalytic effect and chemical activation is reported in this work. The soluble salts act as the in-situ templates to confine the thickness of 3D graphene layers. Meanwhile, the Fe-catalysts greatly improve the graphitization of the graphene matrix, which are easy to be removed by acid treatment. In addition, the KOH activation introduces abundant mesopores into the graphene networks, which facilities the electrolyte permeation. Thus, when using as electrode materials for supercapacitor, the as-obtained 3DMGNs with high electron conductivity, large surface area and hierarchical porous structure exhibit excellent capacitive properties, including high specific capacitance (215 F g-1 at 0.5 A g-1) and superior rate performance (168 F g-1 at 50 A g-1).

Self-assembling graphene-anthraquinone-2-sulphonate supramolecular nanostructures with enhanced energy density for supercapacitors

NASA Astrophysics Data System (ADS)

Gao, Lifang; Gan, Shiyu; Li, Hongyan; Han, Dongxue; Li, Fenghua; Bao, Yu; Niu, Li

2017-07-01

Boosting the energy density of capacitive energy storage devices remains a crucial issue for facilitating applications. Herein, we report a graphene-anthraquinone supramolecular nanostructure by self-assembly for supercapacitors. The sulfonated anthraquinone exhibits high water solubility, a π-conjugated structure and redox active features, which not only serve as a spacer to interact with and stabilize graphene but also introduce extra pseudocapacitance contributions. The formed nest-like three-dimensional (3D) nanostructure with further hydrothermal treatment enhances the accessibility of ion transfer and exposes the redox-active quinone groups in the electrolytes. A fabricated all-solid-state flexible symmetric device delivers a high specific capacitance of 398.5 F g-1 at 1 A g-1 (1.5 times higher than graphene), superior energy density (52.24 Wh kg-1 at about 1 kW kg-1) and good stability (82% capacitance retention after 10 000 cycles).

Oxygen-rich hierarchical porous carbon derived from artemia cyst shells with superior electrochemical performance.

PubMed

Zhao, Yufeng; Ran, Wei; He, Jing; Song, Yanfang; Zhang, Chunming; Xiong, Ding-Bang; Gao, Faming; Wu, Jinsong; Xia, Yongyao

2015-01-21

In this study, three-dimensional (3D) hierarchical porous carbon with abundant functional groups is produced through a very simple low-cost carbonization of Artemia cyst shells. The unique hierarchical porous structure of this material, combining large numbers of micropores and macropores, as well as reasonable amount of mesopores, is proven favorable to capacitive behavior. The abundant oxygen functional groups from the natural carbon precursor contribute stable pseudocapacitance. As-prepared sample exhibits high specific capacitance (369 F g(-1) in 1 M H2SO4 and 349 F g(-1) in 6 M KOH), excellent cycling stability with capacitance retention of 100% over 10 000 cycles, and promising rate performance. This work not only describes a simple way to produce high-performance carbon electrode materials for practical application, but also inspires an idea for future structure design of porous carbon.

Characterization of MoS2-Graphene Composites for High-Performance Coin Cell Supercapacitors.

PubMed

Bissett, Mark A; Kinloch, Ian A; Dryfe, Robert A W

2015-08-12

Two-dimensional materials, such as graphene and molybdenum disulfide (MoS2), can greatly increase the performance of electrochemical energy storage devices because of the combination of high surface area and electrical conductivity. Here, we have investigated the performance of solution exfoliated MoS2 thin flexible membranes as supercapacitor electrodes in a symmetrical coin cell arrangement using an aqueous electrolyte (Na2SO4). By adding highly conductive graphene to form nanocomposite membranes, it was possible to increase the specific capacitance by reducing the resistivity of the electrode and altering the morphology of the membrane. With continued charge/discharge cycles the performance of the membranes was found to increase significantly (up to 800%), because of partial re-exfoliation of the layered material with continued ion intercalation, as well as increasing the specific capacitance through intercalation pseudocapacitance. These results demonstrate a simple and scalable application of layered 2D materials toward electrochemical energy storage.

Hollow Co2P nanoflowers assembled from nanorods for ultralong cycle-life supercapacitors.

PubMed

Cheng, Ming; Fan, Hongsheng; Xu, Yingying; Wang, Rongming; Zhang, Xixiang

2017-09-28

Hollow Co 2 P nanoflowers (Co 2 P HNFs) were successfully prepared via a one-step, template-free method. Microstructure analysis reveals that Co 2 P HNFs are assembled from nanorods and possess abundant mesopores and an amorphous carbon shell. Density functional theory calculations and electrochemical measurements demonstrate the high electrical conductivity of Co 2 P. Benefiting from the unique nanostructures, when employed as an electrode material for supercapacitors, Co 2 P HNFs exhibit a high specific capacitance, an outstanding rate capability, and an ultralong cycling stability. Furthermore, the constructed Co 2 P HNF//AC ASC exhibits a high energy density of 30.5 W h kg -1 at a power density of 850 W kg -1 , along with a superior cycling performance (108.0% specific capacitance retained after 10 000 cycles at 5 A g -1 ). These impressive results make Co 2 P HNFs a promising candidate for supercapacitor applications.

Template-free synthesis of ordered ZnO@ZnS core-shell arrays for high performance supercapacitors.

PubMed

Yan, Hailong; Li, Tong; Lu, Yang; Cheng, Jinbing; Peng, Tao; Xu, Jinyou; Yang, Linying; Hua, Xiangqiang; Liu, Yunxin; Luo, Yongsong

2016-11-28

In this article, ordered ZnO@ZnS core-shell structures have been produced on a stainless mesh by a two-step approach without using a template. ZnO nanorods fabricated by a chemical vapor method are transferred into a 50 ml autoclave for a second stage ion-exchange reaction followed by heating at 120 °C for 4-16 h. The ZnO core is prepared as the conducting channel and ZnS as the active material. Such unique architecture exhibits remarkable electrochemical performance with high capacitance and desirable cycle life. When evaluating as the electrode for supercapacitors, the ZnO@ZnS core-shell structure delivers a high specific capacitance of 603.8 F g -1 at a current density of 2 A g -1 , with 9.4% capacitance loss after cycling 3000 times. The fabrication strategy presented here is simple and cost-effective, which can open new avenues for large-scale applications of the novel materials in energy storage.

Specific methodology for capacitance imaging by atomic force microscopy: A breakthrough towards an elimination of parasitic effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Estevez, Ivan; Concept Scientific Instruments, ZA de Courtaboeuf, 2 rue de la Terre de Feu, 91940 Les Ulis; Chrétien, Pascal

2014-02-24

On the basis of a home-made nanoscale impedance measurement device associated with a commercial atomic force microscope, a specific operating process is proposed in order to improve absolute (in sense of “nonrelative”) capacitance imaging by drastically reducing the parasitic effects due to stray capacitance, surface topography, and sample tilt. The method, combining a two-pass image acquisition with the exploitation of approach curves, has been validated on sets of calibration samples consisting in square parallel plate capacitors for which theoretical capacitance values were numerically calculated.

The Pine-Needle-Inspired Structure of Zinc Oxide Nanorods Grown on Electrospun Nanofibers for High-Performance Flexible Supercapacitors.

PubMed

Sami, Syed Kamran; Siddiqui, Saqib; Shrivastava, Sajal; Lee, Nae-Eung; Chung, Chan-Hwa

2017-12-01

Flexible supercapacitors with high electrochemical performance and stability along with mechanical robustness have gained immense attraction due to the substantial advancements and rampant requirements of storage devices. To meet the exponentially growing demand of microsized energy storage device, a cost-effective and durable supercapacitor is mandatory to realize their practical applications. Here, in this work, the fabrication route of novel electrode materials with high flexibility and charge-storage capability is reported using the hybrid structure of 1D zinc oxide (ZnO) nanorods and conductive polyvinylidene fluoride-tetrafluoroethylene (P(VDF-TrFE)) electrospun nanofibers. The ZnO nanorods are conformably grown on conductive P(VDF-TrFE) nanofibers to fabricate the light-weighted porous electrodes for supercapacitors. The conductive nanofibers acts as a high surface area scaffold with significant electrochemical performance, while the addition of ZnO nanorods further enhances the specific capacitance by 59%. The symmetric cell with the fabricated electrodes presents high areal capacitance of 1.22 mF cm -2 at a current density of 0.1 mA cm -2 with a power density of more than 1600 W kg -1 . Furthermore, these electrodes show outstanding flexibility and high stability with 96% and 78% retention in specific capacitance after 1000 and 5000 cycles, respectively. The notable mechanical durability and robustness of the cell acquire both good flexibility and high performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hierarchical MnO2 nanowire/graphene hybrid fibers with excellent electrochemical performance for flexible solid-state supercapacitors

NASA Astrophysics Data System (ADS)

Ma, Wujun; Chen, Shaohua; Yang, Shengyuan; Chen, Wenping; Cheng, Yanhua; Guo, Yiwei; Peng, Shengjie; Ramakrishna, Seeram; Zhu, Meifang

2016-02-01

Towards rapid development of lightweight, flexible, and even wearable electronics, a highly efficient energy-storage device is required for their energy supply management. Graphene fiber-based supercapacitor is considered as one of the promising candidates because of the remarkable mechanical and electrical properties of graphene fibers. However, supercapacitors based on bare graphene fibers generally suffer a low capacitance, which certainly restricts their potentially wide applications. In this work, hierarchically structured MnO2 nanowire/graphene hybrid fibers are fabricated through a simple, scalable wet-spinning method. The hybrid fibers form mesoporous structure with large specific surface area of 139.9 m2 g-1. The mass loading of MnO2 can be as high as 40 wt%. Due to the synergistic effect between MnO2 nanowires and graphene, the main pseudocapacitance of MnO2 and the electric double-layer capacitance of graphene are improved simultaneously. In view of the practical demonstration, a highly flexible solid-state supercapacitor is fabricated by twisting of two MnO2/graphene fibers coated by polyvinyl alcohol/H3PO4 electrolyte. The supercapacitor exhibits a high volumetric capacitance (66.1 F cm-3, normalized by the total volume of two fiber electrodes), excellent cycling stability (96% capacitance retention over 10,000 cycles), high energy and power density (5.8 mWh cm-3 and 0.51 W cm-3, respectively).

Hierarchical TiN nanoparticles-assembled nanopillars for flexible supercapacitors with high volumetric capacitance.

PubMed

Qin, Ping; Li, Xingxing; Gao, Biao; Fu, Jijiang; Xia, Lu; Zhang, Xuming; Huo, Kaifu; Shen, Wenli; Chu, Paul K

2018-05-10

Titanium nitride (TiN) is an attractive electrode material in fast charging/discharging supercapacitors because of its excellent conductivity. However, the low capacitance and mechanical brittleness of TiN restricts its further application in flexible supercapacitors with high energy density. Thus, it is still a challenge to rationally design TiN electrodes with both high electrochemical and mechanical properties. Herein, the hierarchical TiN nanoparticles-assembled nanopillars (H-TiN NPs) array as binder free electrodes were obtained by nitriding of hierarchical titanium dioxide (TiO2) nanopillars, which was produced by a simple hydrothermal treatment of anodic TiO2 nanotubes (NTs) array in water. The porous TiN nanoparticles connected to each other to form ordered nanopillar arrays, effectively providing larger specific surface area and more active sites for charge storage. The H-TiN NPs delivered a high volumetric capacitance of 120 F cm-3 at 0.83 A cm-3, which is better than that of TiN NTs arrays (69 F cm-3 at 0.83 A cm-3). After assembling into all-solid-state devices, the H-TiN NPs based supercapacitors exhibited outstanding volumetric capacitance of 5.9 F cm-3 at 0.02 A cm-3 and a high energy density of 0.53 mW h cm-3. Our results reveal a new strategy to optimize the supercapacitive performance of metal nitrides.

Nitrogen doped carbon derived from polyimide/multiwall carbon nanotube composites for high performance flexible all-solid-state supercapacitors

NASA Astrophysics Data System (ADS)

Kim, Dae Kyom; Kim, Nam Dong; Park, Seung-Keun; Seong, Kwang-dong; Hwang, Minsik; You, Nam-Ho; Piao, Yuanzhe

2018-03-01

Flexible all-solid-state supercapacitors are desirable as potential energy storage systems for wearable technologies. Herein, we synthesize aminophenyl multiwall carbon nanotube (AP-MWCNT) grafted polyimide precursor by in situ polymerization method as a nitrogen-doped carbon precursor. Flexible supercapacitor electrodes are fabricated via a coating of carbon precursor on carbon cloth surface and carbonization at high temperature directly. The as-obtained electrodes, which can be directly used without any binders or additives, can deliver a high specific capacitance of 333.4 F g-1 at 1 A g-1 (based on active material mass) and excellent cycle stability with 103% capacitance retention after 10,000 cycles in a three-electrode system. The flexible all-solid-state supercapacitor device exhibits a high volumetric capacitance of 3.88 F cm-3 at a current density of 0.02 mA cm-3. And also the device can deliver a maximum volumetric energy density of 0.50 mWh cm-3 and presents good cycling stability with 85.3% capacitance retention after 10,000 cycles. This device cell can not only show extraordinary mechanical flexibilities allowing folding, twisting, and rolling but also demonstrate remarkable stable electrochemical performances under their forms. This work provides a novel approach to obtain carbon textile-based flexible supercapacitors with high electrochemical performance and mechanical flexibility.

SC-CO2-assisted process for a high energy density aerogel supercapacitor: the effect of GO loading

NASA Astrophysics Data System (ADS)

Sarno, Maria; Baldino, Lucia; Scudieri, Carmela; Cardea, Stefano; Ciambelli, Paolo; Reverchon, Ernesto

2017-05-01

Energy density, safety, and simple and environmentally friendly preparation methods are very significant aspects in the realization of a compact supercapacitor. Herein we report the use of a supercritical CO2-assisted gel drying process (SC-CO2) for the preparation of porous electrodes containing dispersed graphene in a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) binder membrane to sandwich in a new portable supercapacitor based on graphene oxide (GO). A GO loading of 60 wt.% was found to give the best combination of factors (porosity, wettability, mechanical and electrochemical properties). Cycling voltammetry and charge/discharge studies showed an excellent capacitance behaviour and stability in an ionic liquid electrolyte, suggesting SC-CO2 processing as a promising platform to produce highly bulky and porous films for supercapacitors. The supercapacitor device delivers a very high energy density of 79.2 Wh kg-1 at a power density of 0.23 KW kg-1 (current density 0.5 A g-1, specific capacitance 36.2 F g-1) while that of steel remains at 50.3 Wh kg-1 at a power density of 2.8 KW kg-1 (current density 6 A g-1, specific capacitance 23.5 F g-1).

SC-CO2-assisted process for a high energy density aerogel supercapacitor: the effect of GO loading.

PubMed

Sarno, Maria; Baldino, Lucia; Scudieri, Carmela; Cardea, Stefano; Ciambelli, Paolo; Reverchon, Ernesto

2017-05-19

Energy density, safety, and simple and environmentally friendly preparation methods are very significant aspects in the realization of a compact supercapacitor. Herein we report the use of a supercritical CO 2 -assisted gel drying process (SC-CO 2 ) for the preparation of porous electrodes containing dispersed graphene in a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) binder membrane to sandwich in a new portable supercapacitor based on graphene oxide (GO). A GO loading of 60 wt.% was found to give the best combination of factors (porosity, wettability, mechanical and electrochemical properties). Cycling voltammetry and charge/discharge studies showed an excellent capacitance behaviour and stability in an ionic liquid electrolyte, suggesting SC-CO 2 processing as a promising platform to produce highly bulky and porous films for supercapacitors. The supercapacitor device delivers a very high energy density of 79.2 Wh kg -1 at a power density of 0.23 KW kg -1 (current density 0.5 A g -1 , specific capacitance 36.2 F g -1 ) while that of steel remains at 50.3 Wh kg -1 at a power density of 2.8 KW kg -1 (current density 6 A g -1 , specific capacitance 23.5 F g -1 ).

N-Doped Porous Carbon Nanofibers/Porous Silver Network Hybrid for High-Rate Supercapacitor Electrode.

PubMed

Meng, Qingshi; Qin, Kaiqiang; Ma, Liying; He, Chunnian; Liu, Enzuo; He, Fang; Shi, Chunsheng; Li, Qunying; Li, Jiajun; Zhao, Naiqin

2017-09-13

A three-dimensional cross-linked porous silver network (PSN) is fabricated by silver mirror reaction using polymer foam as the template. The N-doped porous carbon nanofibers (N-PCNFs) are further prepared on PSN by chemical vapor deposition and treated by ammonia gas subsequently. The PSN substrate serving as the inner current collector will improve the electron transport efficiency significantly. The ammonia gas can not only introduce nitrogen doping into PCNFs but also increase the specific surface area of PCNFs at the same time. Because of its large surface area (801 m 2 /g), high electrical conductivity (211 S/cm), and robust structure, the as-constructed N-PCNFs/PSN demonstrates a specific capacitance of 222 F/g at the current density of 100 A/g with a superior rate capability of 90.8% of its initial capacitance ranging from 1 to 100 A/g while applied as the supercapacitor electrode. The symmetric supercapacitor device based on N-PCNFs/PSN displays an energy density of 8.5 W h/kg with power density of 250 W/kg and excellent cycling stability, which attains 103% capacitance retention after 10 000 charge-discharge cycles at a high current density of 20 A/g, which indicates that N-PCNFs/PSN is a promising candidate for supercapacitor electrode materials.

High Performance All-solid Supercapacitors Based on the Network of Ultralong Manganese dioxide/Polyaniline Coaxial Nanowires

PubMed Central

Zhou, Junli; Yu, Lin; Liu, Wei; Zhang, Xiaodan; Mu, Wei; Du, Xu; Zhang, Zhe; Deng, Yulin

2015-01-01

In recent years, thin, lightweight and flexible solid supercapacitors are of considerable interest as energy storage devices. Here we demonstrated all-solid supercapacitors (SSCs) with high electrochemical properties, low self-discharge characteristics based on manganese dioxide/polyaniline (MNW/PANI) coaxial nanowire networks. The synergistic effect of MnO2/PANI plus the unique coaxial nanostructure of the ultralong nanowires with a highly interconnected network effectively enhance the conductivity and capacitive performance of the SSCs device. The MNW/PANI composite with 62.5% MnO2 exhibits an outstanding areal specific capacitance reaching 346 mF/cm2 at 5 mV s−1 which is significant higher than most previously reported solid supercapacitors (15.3 mF/cm2–109 mF/cm2) and is close to the that of the best graphene films solid state supercapacitors (372 mF/cm2). In contrast, only 190 mF/cm2 of areal specific capacitance was obtained for the pure MnO2 NW network. The supercapacitors also exhibited low leakage current as small as 20.1 μA, which demonstrated that the MNW/PANI SSCs have great potential for practical applications. PMID:26644364

Unrivaled combination of surface area and pore volume in micelle-templated carbon for supercapacitor energy storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pokrzywinski, Jesse; Keum, Jong K.; Ruther, Rose E.

Here, we created Immense Surface Area Carbons (ISACs) by a novel heat treatment that stabilized the micelle structure in a biological based precursor prior to high temperature combined activation – pyrolysis. While displaying a morphology akin to that of commercial activated carbon, ISACs contain an unparalleled combination of electrochemically active surface area and pore volume (up to 4051 m 2 g –1, total pore volume 2.60 cm 3 g –1, 76% small mesopores). The carbons also possess the benefit of being quite pure (combined O and N: 2.6–4.1 at%), thus allowing for a capacitive response that is primarily EDLC. Testedmore » at commercial mass loadings (~10 mg cm –2) ISACs demonstrate exceptional specific capacitance values throughout the entire relevant current density regime, with superior rate capability primarily due to the large fraction of mesopores. In the optimized ISAC, the specific capacitance ( C g) is 540 F g –1 at 0.2 A g –1, 409 F g –1 at 1 A g –1 and 226 F g –1 at a very high current density of 300 A g –1 (~0.15 second charge time). At intermediate and high currents, such capacitance values have not been previously reported for any carbon. Tested with a stable 1.8 V window in a 1 M Li 2SO 4 electrolyte, a symmetric supercapacitor cell yields a flat energy–power profile that is fully competitive with those of organic electrolyte systems: 29 W h kg –1 at 442 W kg –1 and 17 W h kg –1 at 3940 W kg –1. The cyclability of symmetric ISAC cells is also exceptional due to the minimization of faradaic reactions on the carbon surface, with 80% capacitance retention over 100 000 cycles in 1 M Li 2SO 4 and 75 000 cycles in 6 M KOH.« less

Unrivaled combination of surface area and pore volume in micelle-templated carbon for supercapacitor energy storage

DOE PAGES

Pokrzywinski, Jesse; Keum, Jong K.; Ruther, Rose E.; ...

2017-05-23

Here, we created Immense Surface Area Carbons (ISACs) by a novel heat treatment that stabilized the micelle structure in a biological based precursor prior to high temperature combined activation – pyrolysis. While displaying a morphology akin to that of commercial activated carbon, ISACs contain an unparalleled combination of electrochemically active surface area and pore volume (up to 4051 m 2 g –1, total pore volume 2.60 cm 3 g –1, 76% small mesopores). The carbons also possess the benefit of being quite pure (combined O and N: 2.6–4.1 at%), thus allowing for a capacitive response that is primarily EDLC. Testedmore » at commercial mass loadings (~10 mg cm –2) ISACs demonstrate exceptional specific capacitance values throughout the entire relevant current density regime, with superior rate capability primarily due to the large fraction of mesopores. In the optimized ISAC, the specific capacitance ( C g) is 540 F g –1 at 0.2 A g –1, 409 F g –1 at 1 A g –1 and 226 F g –1 at a very high current density of 300 A g –1 (~0.15 second charge time). At intermediate and high currents, such capacitance values have not been previously reported for any carbon. Tested with a stable 1.8 V window in a 1 M Li 2SO 4 electrolyte, a symmetric supercapacitor cell yields a flat energy–power profile that is fully competitive with those of organic electrolyte systems: 29 W h kg –1 at 442 W kg –1 and 17 W h kg –1 at 3940 W kg –1. The cyclability of symmetric ISAC cells is also exceptional due to the minimization of faradaic reactions on the carbon surface, with 80% capacitance retention over 100 000 cycles in 1 M Li 2SO 4 and 75 000 cycles in 6 M KOH.« less

3D nanoporous graphene films converted from liquid-crystalline holey graphene oxide for thin and high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Wang, Bin; Liu, Jinzhang; Zhao, Yi; Zheng, Dezhi; Li, Yan; Sha, Jiangbo

2018-01-01

Holey graphene oxide (HGO) is prepared and its liquid crystal (LC) formation in water is investigated. The blade-coated LC-HGO hydrogel is hydrothermally reduced to form 3D nanoporous films used as supercapacitor electrodes. Holey graphene sheets are rumpled and interconnected to form a cellular structure with pore size around 100 nm during the reduction process. Reduced HGO films with different thicknesses are integrated into solid-state symmetric supercapacitors and their electrochemical performances are studied. High specific capacitance up to 304 F g-1 and high volumetric capacitance around 400 F cm-3 are achieved from our thin and flexible devices.

Facile Co-Electrodeposition Method for High-Performance Supercapacitor Based on Reduced Graphene Oxide/Polypyrrole Composite Film.

PubMed

Chen, Junchen; Wang, Yaming; Cao, Jianyun; Liu, Yan; Zhou, Yu; Ouyang, Jia-Hu; Jia, Dechang

2017-06-14

A facile co-electrodeposition method has been developed to fabricate reduced graphene oxide/polypyrrole (rGO/PPy) composite films, with sodium dodecyl benzene sulfonate as both a surfactant and supporting electrolyte in the precursor solution. The introduction of rGO into the PPy films forms porous structure and enhances the conductivity across the film, leading to superior electrochemical performance. By controlling the deposition time and rGO concentration, the highest area capacitance can reach 411 mF/cm 2 (0.2 mA/cm 2 ) for rGO/PPy films, whereas optimized specific capacitance is as high as 361 F/g (0.2 mA/cm 2 ). All of the composite films exhibit excellent rate capability (at least 175 F/g at the current density of 12 mA/cm 2 ) compared with pure PPy film (only 12 F/g at the current density of 12 mA/cm 2 ). The rGO/PPy composite exhibits excellent cycling stability that maintains 104% of its initial capacitance after cycling for 2000 cycles and 80% for 5000 cycles. The two-electrode solid-state supercapacitor (SC) based on rGO/PPy composite electrodes demonstrates good rate performance, excellent cycling stability, as well as a high area capacitance of 222 mF/cm 2 . The solid-state planar SC based on the rGO/PPy composite exhibits an area capacitance of 9.4 mF/cm 2 , demonstrating great potential for fabrication of microsupercapacitors.

Hydrothermal synthesis of Mn-doped ZnCo2O4 electrode material for high-performance supercapacitor

NASA Astrophysics Data System (ADS)

Mary, A. Juliet Christina; Bose, A. Chandra

2017-12-01

Mn-doped ZnCo2O4 nanoparticle has been synthesized by hydrothermal method without adding any surfactants. Structural, morphological and electrochemical performances have been studied for the pure and various concentration of Mn-doped ZnCo2O4 nanoparticles. XRD and Raman studies demonstrate the crystalline structure of the material. Specific capacitance of the 10 wt% Mn doped ZnCo2O4 nanomaterial is analysed using the three-electrode system. 10 wt% Mn-doped ZnCo2O4 has a maximum capacitance of 707.4 F g-1 at a current density of 0.5 A g-1. Coulombic efficiency of the material is 96.3% for 500 cycles in the KOH electrolyte medium. A two-electrode device using 10 wt% Mn-doped ZnCo2O4 exhibits the highest specific capacitance of 6.5 F g-1 at a current density of 0.03 A g-1 which is the suitable material for supercapacitor application.

A Flexible Cotton-Based Supercapacitor Electrode with High Stability Prepared by Multiwalled CNTs/PANI

NASA Astrophysics Data System (ADS)

Hao, Tianqi; Wang, Wei; Yu, Dan

2018-05-01

Multiwalled nanotubes/cotton composite was prepared firstly as conductive fabric, and then, polyaniline (PANI) doped with multi-walled carbon nanotubes (MWCNTs) were fabricated on the conductive fabric to make flexible cotton-based supercapacitor electrodes. The doping of MWCNTs cannot only provide good conductivity and large specific surface area of the electrode, but also help to increase the loading of aniline monomer in the polyaniline polymerization. Field emission scanning electron microscopy was applied to observe the surface morphology of the composite, and Fourier transform infrared and Energy dispersion spectrum were used to analysis the existence of PANI. Electrochemical tests were adopted to measure the electrochemical performance. The results demonstrated the multivariate mixture composite flexible electrode exhibited a specific capacitance of 590.93 F g-1 at a scan rate of 0.001 V s-1 and an excellent capacitance retention of 89% at 0.1 V s-1 after 3000 cycles. Based on our method, the cycle stability of the composite was great and so was the capacitance retention.

A Flexible Cotton-Based Supercapacitor Electrode with High Stability Prepared by Multiwalled CNTs/PANI

NASA Astrophysics Data System (ADS)

Hao, Tianqi; Wang, Wei; Yu, Dan

2018-07-01

Multiwalled nanotubes/cotton composite was prepared firstly as conductive fabric, and then, polyaniline (PANI) doped with multi-walled carbon nanotubes (MWCNTs) were fabricated on the conductive fabric to make flexible cotton-based supercapacitor electrodes. The doping of MWCNTs cannot only provide good conductivity and large specific surface area of the electrode, but also help to increase the loading of aniline monomer in the polyaniline polymerization. Field emission scanning electron microscopy was applied to observe the surface morphology of the composite, and Fourier transform infrared and Energy dispersion spectrum were used to analysis the existence of PANI. Electrochemical tests were adopted to measure the electrochemical performance. The results demonstrated the multivariate mixture composite flexible electrode exhibited a specific capacitance of 590.93 F g-1 at a scan rate of 0.001 V s-1 and an excellent capacitance retention of 89% at 0.1 V s-1 after 3000 cycles. Based on our method, the cycle stability of the composite was great and so was the capacitance retention.

Vertically Aligned Niobium Nanowire Arrays for Fast-Charging Micro-Supercapacitors.

PubMed

Mirvakili, Seyed M; Hunter, Ian W

2017-07-01

Planar micro-supercapacitors are attractive for system on chip technologies and surface mount devices due to their large areal capacitance and energy/power density compared to the traditional oxide-based capacitors. In the present work, a novel material, niobium nanowires, in form of vertically aligned electrodes for application in high performance planar micro-supercapacitors is introduced. Specific capacitance of up to 1 kF m -2 (100 mF cm -2 ) with peak energy and power density of 2 kJ m -2 (6.2 MJ m -3 or 1.7 mWh cm -3 ) and 150 kW m -2 (480 MW m -3 or 480 W cm -3 ), respectively, is achieved. This remarkable power density, originating from the extremely low equivalent series resistance value of 0.27 Ω (2.49 µΩ m 2 or 24.9 mΩ cm 2 ) and large specific capacitance, is among the highest for planar micro-supercapacitors electrodes made of nanomaterials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

NiCo2O4 particles with diamond-shaped hexahedron structure for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Li, Yanfang; Hou, Xiaojuan; Zhang, Zengxing; Hai, Zhenyin; Xu, Hongyan; Cui, Danfeng; Zhuiykov, Serge; Xue, Chenyang

2018-04-01

Nickel cobalt oxide (NiCo2O4) particles with a diamond-shaped hexahedral porous sheet structure are successfully synthesized by a facile hydrothermal method, followed by calcination in one step. NiCo2O4-I and NiCo2O4-II particles are prepared using the same method with different contents of urea (CO(NH2)2) and ammonium fluoride (NH4F). The different morphologies of the NiCo2O4-I and NiCo2O4-II particles illustrate that CO(NH2)2 and NH4F play an important role in crystal growth. To verify the influence of NH4F and CO(NH2)2 on the morphology of the NiCo2O4 particles, the theory of crystal growth morphology is analyzed. The electrochemical measurements show that NiCo2O4 particles exhibit a high specific capacitance. At a current density of 1.0 mA cm-2, the mass specific capacitances of the NiCo2O4-I and NiCo2O4-II electrodes are 690.75 and 1710.9 F g-1, respectively, in a 6 M KOH aqueous electrolyte. The specific capacitances of the NiCo2O4-I and NiCo2O4-II electrodes remain ∼95.95% and ∼70.58% of the initial capacitance values after 5000 cycles, respectively. According to the two-electrode test, the NiCo2O4-II//AC asymmetric electrodes exhibited an ultrahigh energy density of 64.67 Wh kg-1 at the power density of 12 kW kg-1, demonstrating its excellent application potential as an electrode material for supercapacitors.

Interconnected 3 D Network of Graphene-Oxide Nanosheets Decorated with Carbon Dots for High-Performance Supercapacitors.

PubMed

Zhao, Xiao; Li, Ming; Dong, Hanwu; Liu, Yingliang; Hu, Hang; Cai, Yijin; Liang, Yeru; Xiao, Yong; Zheng, Mingtao

2017-06-22

Interconnected 3 D nanosheet networks of reduced graphene oxide decorated with carbon dots (rGO/CDs) are successfully fabricated through a simple one-pot hydrothermal process. The as-prepared rGO/CDs present appropriate 3 D interconnectivity and abundant stable oxygen-containing functional groups, to which we can attribute the excellent electrochemical performance such as high specific capacitance, good rate capability, and great cycling stability. Employed as binder-free electrodes for supercapacitors, the resulting rGO/CDs exhibit excellent long-term cycling stability (ca. 92 % capacitance retention after 20 000 charge/discharge cycles at current density of 10 A g -1 ) as well as a maximum specific capacitance of about 308 F g -1 at current density of 0.5 A g -1 , which is much higher than that of rGO (200 F g -1 ) and CDs (2.2 F g -1 ). This work provides a promising strategy to fabricate graphene-based nanomaterials with greatly boosted electrochemical performances by decoration of with CDs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

High Performance of N-Doped Graphene with Bubble-like Textures for Supercapacitors.

PubMed

Zhang, Shuo; Sui, Lina; Kang, Hongquan; Dong, Hongzhou; Dong, Lifeng; Yu, Liyan

2018-02-01

Nitrogen-doped graphene (NG) with wrinkled and bubble-like texture is fabricated by a thermal treatment. Especially, a novel sonication-assisted pretreatment with nitric acid is used to further oxidize graphene oxide and its binding with melamine molecules. There are many bubble-like nanoflakes with a dimension of about 10 nm appeared on the undulated graphene nanosheets. The bubble-like texture provides more active sites for effective ion transport and reversible capacitive behavior. The specific surface area of NG (5.03 at% N) can reach up to 438.7 m 2 g -1 , and the NG electrode demonstrates high specific capacitance (481 F g -1 at 1 A g -1 , four times higher than reduced graphene oxide electrode (127.5 F g -1 )), superior cycle stability (the capacitance retention of 98.9% in 2 m KOH and 99.2% in 1 m H 2 SO 4 after 8000 cycles), and excellent energy density (42.8 Wh kg -1 at power density of 500 W kg -1 in 2 m KOH aqueous electrolyte). The results indicate the potential use of NG as graphene-based electrode material for energy storage devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flexible all-solid-state supercapacitors based on graphene/carbon black nanoparticle film electrodes and cross-linked poly(vinyl alcohol)-H2SO4 porous gel electrolytes

NASA Astrophysics Data System (ADS)

Fei, Haojie; Yang, Chongyang; Bao, Hua; Wang, Gengchao

2014-11-01

Flexible all-solid-state supercapacitors (SCs) are fabricated using graphene/carbon black nanoparticle (GCB) film electrodes and cross-linked poly(vinyl alcohol)-H2SO4 porous gel electrolytes (gPVAP-H2SO4). The GCB composite films, with carbon black (CB) nanoparticles uniformly distributed in the graphene nanosheets, greatly improve the active surface areas and ion transportation of pristine graphene film. The porous structure of as-prepared gPVAP-H2SO4 membrane improves the equilibrium swelling ratio in electrolyte and provides interconnected ion transport channels. The chemical crosslinking solves the fluidity problem of PVA-H2SO4 gel electrolyte at high temperature. As-fabricated GCB//gPVAP(20)-H2SO4//GCB flexible SC displays an increased specific capacitance (144.5 F g-1 at 0.5 A g-1) and a higher specific capacitance retention (67.9% from 0.2 to 4 A g-1). More importantly, the flexible SC possesses good electrochemical performance at high temperature (capacitance retention of 78.3% after 1000 cycles at 70 °C).

Nanocoating covalent organic frameworks on nickel nanowires for greatly enhanced-performance supercapacitors

NASA Astrophysics Data System (ADS)

Han, Yang; Hu, Nantao; Liu, Shuai; Hou, Zhongyu; Liu, Jiaqiang; Hua, Xiaolin; Yang, Zhi; Wei, Liangming; Wang, Lin; Wei, Hao

2017-08-01

Nanocoatings of covalent organic frameworks (COFs) on nickel nanowires (NiNWs) have been designed and successfully fabricated for the first time, which showed greatly enhanced electrochemical performances for supercapacitors. The specific capacitance of electrodes based on as-fabricated COFs nanocoatings reached up to 314 F g-1 at 50 A g-1, which retained 74% of the specific capacitance under the current density of 2 A g-1. The ultrahigh current density makes the charge-discharge process extremely rapid. The outstanding electrochemical performances of COFs nanocoating on NiNWs make it an ideal candidate for supercapacitors. And the nanocoating-design can also give a guidance for application of COFs in high-performance energy storages.

Hierarchical Branched Vanadium Oxide Nanorod@Si Nanowire Architecture for High Performance Supercapacitors.

PubMed

Li, Zhaodong; Wang, Fei; Wang, Xudong

2017-01-01

Vanadium oxide (VO x ) nanorods are uniformly synthesized on dense Si nanowire arrays. This 3D hierarchical nanoarchitecture offers a novel high-performance supercapacitor electrode design with significantly improved specific capacitance and high-rate capability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel Designs for Application Specific MEMS Pressure Sensors

PubMed Central

Fragiacomo, Giulio; Reck, Kasper; Lorenzen, Lasse; Thomsen, Erik V.

2010-01-01

In the framework of developing innovative microfabricated pressure sensors, we present here three designs based on different readout principles, each one tailored for a specific application. A touch mode capacitive pressure sensor with high sensitivity (14 pF/bar), low temperature dependence and high capacitive output signal (more than 100 pF) is depicted. An optical pressure sensor intrinsically immune to electromagnetic interference, with large pressure range (0–350 bar) and a sensitivity of 1 pm/bar is presented. Finally, a resonating wireless pressure sensor power source free with a sensitivity of 650 KHz/mmHg is described. These sensors will be related with their applications in harsh environment, distributed systems and medical environment, respectively. For many aspects, commercially available sensors, which in vast majority are piezoresistive, are not suited for the applications proposed. PMID:22163425

Activated graphene as a cathode material for Li-ion hybrid supercapacitors.

PubMed

Stoller, Meryl D; Murali, Shanthi; Quarles, Neil; Zhu, Yanwu; Potts, Jeffrey R; Zhu, Xianjun; Ha, Hyung-Wook; Ruoff, Rodney S

2012-03-14

Chemically activated graphene ('activated microwave expanded graphite oxide', a-MEGO) was used as a cathode material for Li-ion hybrid supercapacitors. The performance of a-MEGO was first verified with Li-ion electrolyte in a symmetrical supercapacitor cell. Hybrid supercapacitors were then constructed with a-MEGO as the cathode and with either graphite or Li(4)Ti(5)O(12) (LTO) for the anode materials. The results show that the activated graphene material works well in a symmetrical cell with the Li-ion electrolyte with specific capacitances as high as 182 F g(-1). In a full a-MEGO/graphite hybrid cell, specific capacitances as high as 266 F g(-1) for the active materials at operating potentials of 4 V yielded gravimetric energy densities for a packaged cell of 53.2 W h kg(-1).

Ternary nitrogen-doped graphene/nickel ferrite/polyaniline nanocomposites for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Wang, Wenjuan; Hao, Qingli; Lei, Wu; Xia, Xifeng; Wang, Xin

2014-12-01

The electrochemical property of graphene can be significantly enhanced due to the incorporating of heteroatoms into graphene. In this article, the ternary nitrogen-doped graphene/nickel ferrite/polyaniline (NGNP) nanocomposite is synthesized by a facile two-step approach and its electrochemical properties as electrodes for supercapacitors are studied by various electrochemical measurements. The specific capacitance of NGNP is 645.0 F g-1 at 1 mV s-1 and 667.0 F g-1 at 0.1 A g-1 in a three- and two-electrode system, respectively, much higher than other binary electrodes. In a two-electrode symmetric system, the energy density of the NGNP electrode is 92.7 W h kg-1 at a power density of 110.8 W kg-1, moreover, that of the supercapacitor based on NGNP can also reach 23.2 W h kg-1 at a power density of 27.7 W kg-1. In addition, the capacitance loses only 5% after repeating test for 5000 cycles, and about 10% after 10,000 cycles at a high current density 5 A g-1. The results demonstrate the novel ternary NGNP electrode produced by the current economical method will gain promising applications in supercapacitors and other devices by virtue of its outstanding characteristics (high specific capacitance, high power and energy density, excellent cycle life).

Three-Dimensional Hierarchically Mesoporous ZnCo2 O4 Nanowires Grown on Graphene/Sponge Foam for High-Performance, Flexible, All-Solid-State Supercapacitors.

PubMed

Moon, In Kyu; Yoon, Seonno; Oh, Jungwoo

2017-01-12

To achieve high energy storage on three-dimensional (3D) structures at low cost, materials with high power and long cycle life characteristics have to be developed. We synthesized ZnCo 2 O 4 /reduced graphene oxide (rGO) binary composites in commercial sponges. ZnCo 2 O 4 nanosheets were grown on the surface of GO/sponge through a hydrothermal reaction. The resulting flexible, free-standing ZnCo 2 O 4 /rGO/sponge electrodes were used as the electrodes in a symmetric supercapacitor. ZnCo 2 O 4 /rGO/sponge electrodes have a large specific capacitance of 1116.6 F g -1 at a scan rate of 2 mV s -1 in aqueous electrolyte. The all-solid-state flexible supercapacitor is assembled based on ZnCo 2 O 4 /rGO/sponge electrodes, which show excellent electrochemical performances with a specific capacitance of 143 F g -1 at a current density of 1 A g -1 . The as-fabricated supercapacitor also exhibits excellent cycling stability (93.4 % capacitance retention after 5000 cycles) and exceptional mechanical flexibility. These results demonstrate the potential of ZnCo 2 O 4 /rGO/sponge as an electrode in flexible, high-performance supercapacitors. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hierarchically porous carbon nanosheets derived from Moringa oleifera stems as electrode material for high-performance electric double-layer capacitors

NASA Astrophysics Data System (ADS)

Cai, Yijin; Luo, Ying; Dong, Hanwu; Zhao, Xiao; Xiao, Yong; Liang, Yeru; Hu, Hang; Liu, Yingliang; Zheng, Mingtao

2017-06-01

A facile one-step pyrolysis route for the synthesis of hierarchically porous carbon nanosheets (PCNSs) derived from Moringa oleifera stems (MOSs) is reported, in which no post-activation-process in needed. The as-prepared PCNSs possesses unique porous nanosheet morphology with high specific surface area of ca. 2250 m2 g-1, large pore volume of ca. 2.3 cm3 g-1, appropriate porosity as well as heteroatom doping (N and O), endowing outstanding electrochemical properties as electrode material for high-performance supercapacitors. The PCNS-based electrodes are investigated in various aqueous electrolytes including 1.0 M Na2SO4, 1.0 M H2SO4, and 6.0 M KOH. The PCNSs exhibit a maximum specific capacitance of ca. 283 F g-1 (0.5 A g-1), excellent rate capability (ca. 72% of capacitance retention even at an ultrahigh current density of 50 A g-1), and a tremendous long-term cycling stability in the three-electrode system. Moreover, the as-assembled PCNS-based symmetric supercapacitor shows a high energy density of ca. 25.8 Wh kg-1 (in 1.0 M Na2SO4 electrolyte) and remarkable long-term cycling stability (almost no capacitance fade in aqueous electrolytes), indicating the promising of the as-prepared PCNSs for electrochemical energy storage and conversion.

Synthesis, characterization and electrochemical performance of graphene decorated with 1D NiMoO4.nH2O nanorods

NASA Astrophysics Data System (ADS)

Ghosh, Debasis; Giri, Soumen; Das, Chapal Kumar

2013-10-01

One-dimensional NiMoO4.nH2O nanorods and their graphene based hybrid composite with good electrochemical properties have been synthesized by a cost effective hydrothermal procedure. The formation of the mixed metal oxide and the composite was confirmed by XRD, XPS and Raman analyses. The morphological characterizations were carried out using FESEM and TEM analyses. The materials were subjected to electrochemical characterization through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies with 6 M KOH as the supporting electrolyte. For NiMoO4.nH2O, a maximum specific capacitance of 161 F g-1 was obtained at 5 A g-1 current density, accompanied with an energy density of 4.53 W h kg-1 at a steady power delivery rate of 1125 W kg-1. The high utility of the pseudocapacitive NiMoO4.nH2O was achieved in its graphene based composite, which exhibited a high specific capacitance of 367 F g-1 at 5 A g-1 current density and a high energy density of 10.32 W h kg-1 at a power density of 1125 W kg-1 accompanied with long term cyclic stability.One-dimensional NiMoO4.nH2O nanorods and their graphene based hybrid composite with good electrochemical properties have been synthesized by a cost effective hydrothermal procedure. The formation of the mixed metal oxide and the composite was confirmed by XRD, XPS and Raman analyses. The morphological characterizations were carried out using FESEM and TEM analyses. The materials were subjected to electrochemical characterization through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies with 6 M KOH as the supporting electrolyte. For NiMoO4.nH2O, a maximum specific capacitance of 161 F g-1 was obtained at 5 A g-1 current density, accompanied with an energy density of 4.53 W h kg-1 at a steady power delivery rate of 1125 W kg-1. The high utility of the pseudocapacitive NiMoO4.nH2O was achieved in its graphene based composite, which exhibited a high specific capacitance of 367 F g-1 at 5 A g-1 current density and a high energy density of 10.32 W h kg-1 at a power density of 1125 W kg-1 accompanied with long term cyclic stability. Electronic supplementary information (ESI) available: Materials used, characterization techniques and preparation of electrode, tables containing specific capacitance, coulombic efficiency, energy density and power density values at different current densities of NiMoO4.nH2O and Gr-NiMoO4.nH2O. See DOI: 10.1039/c3nr02444j

MnO 2 nanotube and nanowire arrays by electrochemical deposition for supercapacitors

NASA Astrophysics Data System (ADS)

Xia, Hui; Feng, Jinkui; Wang, Hailong; Lai, Man On; Lu, Li

Highly ordered MnO 2 nanotube and nanowire arrays are successfully synthesized via a electrochemical deposition technique using porous alumina templates. The morphologies and microstructures of the MnO 2 nanotube and nanowire arrays are investigated by field emission scanning electron microscopy and transmission electron microscopy. Electrochemical characterization demonstrates that the MnO 2 nanotube array electrode has superior capacitive behaviour to that of the MnO 2 nanowire array electrode. In addition to high specific capacitance, the MnO 2 nanotube array electrode also exhibits good rate capability and good cycling stability, which makes it promising candidate for supercapacitors.

Nitrogen-enriched hierarchically porous carbons prepared from polybenzoxazine for high-performance supercapacitors.

PubMed

Wan, Liu; Wang, Jianlong; Xie, Lijing; Sun, Yahui; Li, Kaixi

2014-09-10

Nitrogen-enriched hierarchically porous carbons (HPCs) were synthesized from a novel nitrile-functionalized benzoxazine based on benzoxazine chemistry using a soft-templating method and a potassium hydroxide (KOH) chemical activation method and used as electrode materials for supercapacitors. The textural and chemical properties could be easily tuned by adding a soft template and changing the activation temperature. The introduction of the soft-templating agent (surfactant F127) resulted in the formation of mesopores, which facilitated fast ionic diffusion and reduced the internal resistance. The micropores of HPCs were extensively developed by KOH activation to provide large electrochemical double-layer capacitance. As the activation temperature increased from 600 to 800 °C, the specific surface area of nitrogen-enriched carbons increased dramatically, micropores were enlarged, and more meso/macropores were developed, but the nitrogen and oxygen content decreased, which affected the electrochemical performance. The sample HPC-800 activated at 800 °C possesses a high specific surface area (1555.4 m(2) g(-1)), high oxygen (10.61 wt %) and nitrogen (3.64 wt %) contents, a hierarchical pore structure, a high graphitization degree, and good electrical conductivity. It shows great pseudocapacitance and the largest specific capacitance of 641.6 F g(-1) at a current density of 1 A g(-1) in a 6 mol L(-1) KOH aqueous electrolyte when measured in a three-electrode system. Furthermore, the HPC-800 electrode exhibits excellent rate capability (443.0 F g(-1) remained at 40 A g(-1)) and good cycling stability (94.3% capacitance retention over 5000 cycles).

Hydrous Ruthenium Oxide Nanoparticles Anchored to Graphene and Carbon Nanotube Hybrid Foam for Supercapacitors

PubMed Central

Wang, Wei; Guo, Shirui; Lee, Ilkeun; Ahmed, Kazi; Zhong, Jiebin; Favors, Zachary; Zaera, Francisco; Ozkan, Mihrimah; Ozkan, Cengiz S.

2014-01-01

In real life applications, supercapacitors (SCs) often can only be used as part of a hybrid system together with other high energy storage devices due to their relatively lower energy density in comparison to other types of energy storage devices such as batteries and fuel cells. Increasing the energy density of SCs will have a huge impact on the development of future energy storage devices by broadening the area of application for SCs. Here, we report a simple and scalable way of preparing a three-dimensional (3D) sub-5 nm hydrous ruthenium oxide (RuO2) anchored graphene and CNT hybrid foam (RGM) architecture for high-performance supercapacitor electrodes. This RGM architecture demonstrates a novel graphene foam conformally covered with hybrid networks of RuO2 nanoparticles and anchored CNTs. SCs based on RGM show superior gravimetric and per-area capacitive performance (specific capacitance: 502.78 F g−1, areal capacitance: 1.11 F cm−2) which leads to an exceptionally high energy density of 39.28 Wh kg−1 and power density of 128.01 kW kg−1. The electrochemical stability, excellent capacitive performance, and the ease of preparation suggest this RGM system is promising for future energy storage applications. PMID:24663242

A high-capacitance flexible solid-state supercapacitor based on polyaniline and Metal-Organic Framework (UiO-66) composites

NASA Astrophysics Data System (ADS)

Shao, Liang; Wang, Qian; Ma, Zhonglei; Ji, Zhanyou; Wang, Xiaoying; Song, Doudou; Liu, Yuguo; Wang, Ni

2018-03-01

Metal-Organic Frameworks (MOFs) attract increasing attention in the field of energy storage, however, poor conductivity in most MOFs largely hinders their electrical properties. In this work, an effective strategy is developed to make the polyaniline (PANI) molecular chains grow in the pores of UiO-66 as one of the MOFs (labeled as PANI/UiO-66) to form a fixed interpenetrating network structure by using the highly stable porous MOFs, through a variety of synergistic effects to enhance the conductivity and electrochemical properties. Moreover, the design and analysis about PANI/UiO-66 is reported for the first time to our knowledge. In addition, PANI/UiO-66 exhibits an extraordinary capacitance of 1015 F g-1 at 1 A g-1 by electrochemical test. At the same time, the symmetric flexible solid-state supercapacitors is also assembled and tested. The resultant supercapacitor shows a favorable specific capacitance of 647 F g-1 at 1 A g-1 and a high cycling stability (91% capacitance retention after 5000 cycles). The bending test indicates that the obtained supercapacitor is flexible and its performance is only decreased 10% after 800 bending cycles with a bending angle of 180. This flexible solid-state supercapacitor shows great potential in energy storage device.

Studying tantalum-based high-κ dielectrics in terms of capacitance measurements

NASA Astrophysics Data System (ADS)

Stojanovska-Georgievska, L.

2016-08-01

The trend of rapid development of microelectronics towards nano-miniaturization dictates the inevitable introduction of dielectrics with high permittivity (high-κ dielectrics), as alternative material for replacing SiO2. Therefore, studying these materials in terms of their characteristics, especially in terms of reliability, is of great importance for proper design and manufacture of devices. In this paper, alteration of capacitance in different frequency regimes is used, in order to determine the overall behavior of the material. Samples investigated here are MOS structures containing nanoscale tantalum based dielectrics. Layers of pure Ta2O5, but also Hf and Ti doped tantalum pentoxide, i.e. Ta2O5:Hf and Ta2O5:Ti are studied here. All samples are considered as ultrathin oxide layers with thicknesses less than 15 nm, obtained by radio frequent sputtering on p-type silicon substrate. Measuring capacitive characteristics enables determination of several specific parameters of the structures. The obtained results for capacitance in accumulation, the thickness and time evolution of the interfacial SiO2 layer, values of flatband and threshold voltage, density of oxide charges, interfacial and border states, and reliability properties favor the possibilities for more intensive use of studied materials in new nanoelectronic technologies.

Hydrous ruthenium oxide nanoparticles anchored to graphene and carbon nanotube hybrid foam for supercapacitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wei; Guo, S.; Lee, I.

2014-03-25

In real life applications, supercapacitors (SCs) often can only be used as part of a hybrid system together with other high energy storage devices due to their relatively lower energy density in comparison to other types of energy storage devices such as batteries and fuel cells. Increasing the energy density of SCs will have a huge impact on the development of future energy storage devices by broadening the area of application for SCs. Here, we report a simple and scalable way of preparing a three-dimensional (3D) sub-5 nm hydrous ruthenium oxide (RuO₂) anchored graphene and CNT hybrid foam (RGM) architecturemore » for high-performance supercapacitor electrodes. This RGM architecture demonstrates a novel graphene foam conformally covered with hybrid networks of RuO₂ nanoparticles and anchored CNTs. SCs based on RGM show superior gravimetric and per-area capacitive performance (specific capacitance: 502.78 F g⁻¹, areal capacitance: 1.11 F cm⁻²) which leads to an exceptionally high energy density of 39.28 Wh kg⁻¹ and power density of 128.01 kW kg⁻¹. The electrochemical stability, excellent capacitive performance, and the ease of preparation suggest this RGM system is promising for future energy storage applications.« less

An asymmetric supercapacitor with ultrahigh energy density based on nickle cobalt sulfide nanocluster anchoring multi-wall carbon nanotubes hybrid

NASA Astrophysics Data System (ADS)

Wen, Ping; Fan, Mingjin; Yang, Desuo; Wang, Yan; Cheng, Hualei; Wang, Jinqing

2016-07-01

The development of novel electrode materials with high energy density and long cycling life is critical to realize electrochemical capacitive energy storage for practical applications. In this paper, the hybrids of nickle cobalt sulfide/multi-wall carbon nanotubes (NiCo2S4/MWCNTs) with different contents of MWCNTs are prepared using a facile one-pot solvothermal reaction. As novel active materials for supercapacitors, the electrochemistry tests show that the hybrid of NiCo2S4/MWCNTs-5 is able to deliver a high specific capacitance of 2080 F g-1 at the current density of 1 A g-1, even superior rate capability of 61% capacitance retention after a 20-fold increase in current densities, when the content of MWCNTs is up to 5%. More importantly, an asymmetric supercapacitor assembled by NiCo2S4/MWCNTs-5 as positive electrode and reduced graphene oxide (rGO) as negative electrode delivers a high energy density of 51.8 Wh Kg-1 at a power density of 865 W kg-1, and 85.7% of its initial capacitance is retained at the current density of 4 A g-1 after 5000 charge-discharge cycles, exhibiting potential prospect for practical applications.

A high energy and power sodium-ion hybrid capacitor based on nitrogen-doped hollow carbon nanowires anode

NASA Astrophysics Data System (ADS)

Li, Dongdong; Ye, Chao; Chen, Xinzhi; Wang, Suqing; Wang, Haihui

2018-04-01

The sodium ion hybrid capacitor (SHC) has been attracting much attention. However, the SHC's power density is significantly confined to a low level due to the sluggish ion diffusion in the anode. Herein, we propose to use an electrode with a high double layer capacitance as the anode in the SHC instead of insertion anodes. To this aim, nitrogen doped hollow carbon nanowires (N-HCNWs) with a high specific surface area are prepared, and the high capacitive contribution during the sodium ion storage process is confirmed by a series of electrochemical measurements. A new SHC consisting of a N-HCNW anode and a commercial active carbon (AC) cathode is fabricated for the first time. Due to the hybrid charge storage mechanism combining ion insertion and capacitive process, the as-fabricated SHC strikes a balance between the energy density and power density, a energy density of 108 Wh kg-1 and a power density of 9 kW kg-1 can be achieved, which overwhelms the electrochemical performances of most reported AC-based SHCs.

Significant Performance Enhancement in Asymmetric Supercapacitors based on Metal Oxides, Carbon nanotubes and Neutral Aqueous Electrolyte

PubMed Central

Singh, Arvinder; Chandra, Amreesh

2015-01-01

Amongst the materials being investigated for supercapacitor electrodes, carbon based materials are most investigated. However, pure carbon materials suffer from inherent physical processes which limit the maximum specific energy and power that can be achieved in an energy storage device. Therefore, use of carbon-based composites with suitable nano-materials is attaining prominence. The synergistic effect between the pseudocapacitive nanomaterials (high specific energy) and carbon (high specific power) is expected to deliver the desired improvements. We report the fabrication of high capacitance asymmetric supercapacitor based on electrodes of composites of SnO2 and V2O5 with multiwall carbon nanotubes and neutral 0.5 M Li2SO4 aqueous electrolyte. The advantages of the fabricated asymmetric supercapacitors are compared with the results published in the literature. The widened operating voltage window is due to the higher over-potential of electrolyte decomposition and a large difference in the work functions of the used metal oxides. The charge balanced device returns the specific capacitance of ~198 F g−1 with corresponding specific energy of ~89 Wh kg−1 at 1 A g−1. The proposed composite systems have shown great potential in fabricating high performance supercapacitors. PMID:26494197

Significant Performance Enhancement in Asymmetric Supercapacitors based on Metal Oxides, Carbon nanotubes and Neutral Aqueous Electrolyte

NASA Astrophysics Data System (ADS)

Singh, Arvinder; Chandra, Amreesh

2015-10-01

Amongst the materials being investigated for supercapacitor electrodes, carbon based materials are most investigated. However, pure carbon materials suffer from inherent physical processes which limit the maximum specific energy and power that can be achieved in an energy storage device. Therefore, use of carbon-based composites with suitable nano-materials is attaining prominence. The synergistic effect between the pseudocapacitive nanomaterials (high specific energy) and carbon (high specific power) is expected to deliver the desired improvements. We report the fabrication of high capacitance asymmetric supercapacitor based on electrodes of composites of SnO2 and V2O5 with multiwall carbon nanotubes and neutral 0.5 M Li2SO4 aqueous electrolyte. The advantages of the fabricated asymmetric supercapacitors are compared with the results published in the literature. The widened operating voltage window is due to the higher over-potential of electrolyte decomposition and a large difference in the work functions of the used metal oxides. The charge balanced device returns the specific capacitance of ~198 F g-1 with corresponding specific energy of ~89 Wh kg-1 at 1 A g-1. The proposed composite systems have shown great potential in fabricating high performance supercapacitors.

Boosting the Supercapacitance of Nitrogen-Doped Carbon by Tuning Surface Functionalities.

PubMed

Biemolt, Jasper; Denekamp, Ilse M; Slot, Thierry K; Rothenberg, Gadi; Eisenberg, David

2017-10-23

The specific capacitance of a highly porous, nitrogen-doped carbon is nearly tripled by orthogonal optimization of the microstructure and surface chemistry. First, the carbons' hierarchical pore structure and specific surface area were tweaked by controlling the temperature and sequence of the thermal treatments. The best process (pyrolysis at 900 °C, washing, and subsequent annealing at 1000 °C) yielded a carbon with a specific capacitance of 117 F g -1 -nearly double that of a carbon made by a typical single-step synthesis at 700 °C. Following the structural optimization, the surface chemistry of the carbons was enriched by applying an oxidation routine based on a mixture of nitric and sulfuric acid in a 1:4 ratio at two different treatment temperatures (0 and 20 °C) and different treatment times. The optimal treatment times were 4 h at 0 °C and only 1 h at 20 °C. Overall, the specific capacitance nearly tripled relative to the original carbon, reaching 168 F g -1 . The inherent nitrogen doping of the carbon comes into interplay with the acid-induced surface functionalization, creating a mixture of oxygen- and nitrogen-oxygen functionalities. The evolution of the surface chemistry was carefully followed by X-ray photoelectron spectroscopy and by N 2 sorption porosimetry, revealing stepwise surface functionalization and simultaneous carbon etching. Overall, these processes are responsible for the peak-shaped capacitance trends in the carbons. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Supercapacitors based on pillared graphene nanostructures.

PubMed

Lin, Jian; Zhong, Jiebin; Bao, Duoduo; Reiber-Kyle, Jennifer; Wang, Wei; Vullev, Valentine; Ozkan, Mihrimah; Ozkan, Cengiz S

2012-03-01

We describe the fabrication of highly conductive and large-area three dimensional pillared graphene nanostructure (PGN) films from assembly of vertically aligned CNT pillars on flexible copper foils for applications in electric double layer capacitors (EDLC). The PGN films synthesized via a one-step chemical vapor deposition process on flexible copper foils exhibit high conductivity with sheet resistance as low as 1.6 ohms per square and possessing high mechanical flexibility. Raman spectroscopy indicates the presence of multi walled carbon nanotubes (MWCNT) and their morphology can be controlled by the growth conditions. It was discovered that nitric acid treatment can significantly increase the specific capacitance of the devices. EDLC devices based on PGN electrodes (surface area of 565 m2/g) demonstrate enhanced performance with specific capacitance value as high as 330 F/g extracted from the current density-voltage (CV) measurements and energy density value of 45.8 Wh/kg. The hybrid graphene-CNT nanostructures are attractive for applications including supercapacitors, fuel cells and batteries.

Ultrathin porous NiCo2O4 nanosheet arrays on flexible carbon fabric for high-performance supercapacitors.

PubMed

Du, Jun; Zhou, Gang; Zhang, Haiming; Cheng, Chao; Ma, Jianmin; Wei, Weifeng; Chen, Libao; Wang, Taihong

2013-08-14

NiCo2O4 with higher specific capacitance is an excellent pseudocapacitive material. However, the bulk NiCo2O4 material prevents the achievement of high energy desity and great rate performance due to the limited electroactive surface area. In this work, NiCo2O4 nanosheet arrays were deposited on flexible carbon fabric (CF) as a high-performance electrode for supercapacitors. The NiCo2O4 arrays were constructed by interconnected ultrathin nanosheets (10 nm) with many interparticle pores. The porous feature of NiCo2O4 nanosheets increases the amount of electroactive sites and facilitates the electrolyte penetration. Hence, the NiCo2O4/CF composites exhibited a high specific capacitance of 2658 F g(-1) (2 A g(-1)), good rate performance, and superior cycling life, suggesting the NiCo2O4/CF is a promising electrode material for flexible electrochemical capacitors.

Flute type micropores activated carbon from cotton stalk for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Tian, Xun; Ma, Hongru; Li, Zhe; Yan, Shaocun; Ma, Lei; Yu, Feng; Wang, Gang; Guo, Xuhong; Ma, Yanqing; Wong, Chingping

2017-08-01

Flute type micropores activated carbon (FTMAC) has been successfully obtained from cotton stalk via KOH-chemical activation method. The synthesized carbon material exhibits an ordered pore structure with high specific surface area of 1964.46 m2 g-1 and pore volume of 1.03 m3 g-1. The assembled FTMAC-based electrode delivers a high specific capacitance of 254 F g-1 at a current density of 0.2 A g-1 in 1 M H2SO4 aqueous electrolyte. It still can maintain 221 F g-1at a current density of 10 A g-1, demonstrating a good rate capacity (87% retention), as well as long cyclic stability of 96% capacitance retention after 10000 charging and discharging cycles at current density of 1 A g-1. Moreover, the symmetric supercapacitor can deliver a high energy density of 18.14 W h kg-1 and a power density of 450.37 W kg-1 which is operated in the voltage range of 0-1.8 V.

Diamond and Carbon Nanotube Composites for Supercapacitor Devices

NASA Astrophysics Data System (ADS)

Moreira, João Vitor Silva; May, Paul William; Corat, Evaldo José; Peterlevitz, Alfredo Carlos; Pinheiro, Romário Araújo; Zanin, Hudson

2017-02-01

We report on the synthesis and electrochemical properties of diamond grown onto vertically aligned carbon nanotubes with high surface areas as a template, resulting in a composite material exhibiting high double-layer capacitance as well as low electrochemical impedance electrodes suitable for applications as supercapacitor devices. We contrast results from devices fabricated with samples which differ in both their initial substrates (Si and Ti) and their final diamond coatings, such as boron-doped diamond and diamond-like carbon (DLC). We present for first time a conducting model for non-doped DLC thin-films. All samples were characterized by scanning and transmission electron microscopy and Fourier transform infrared and Raman spectroscopy. Our results show specific capacitance as high as 8.25 F g-1 (˜1 F cm-2) and gravimetric specific energy and power as high as 0.7 W h kg-1 and 176.4 W kg-1, respectively, which suggest that these diamond/carbon nanotube composite electrodes are excellent candidates for supercapacitor fabrication.

Amorphous V-O-C composite nanofibers electrospun from solution precursors as binder- and conductive additive-free electrodes for supercapacitors with outstanding performance.

PubMed

Chen, Xia; Zhao, Bote; Cai, Yong; Tadé, Moses O; Shao, Zongping

2013-12-21

Flexible V-O-C composite nanofibers were fabricated from solution precursors via electrospinning and were investigated as free-standing and additive-free film electrodes for supercapacitors. Specifically, composite nanofibers (V0, V5, V10 and V20) with different vanadyl acetylacetonate (VO(acac)2) contents of 0, 5, 10 and 20 wt% with respect to polyacrylonitrile (PAN) were prepared. The composite nanofibers were comparatively studied using XRD, Raman spectroscopy, XPS, N2 adsorption-desorption, FE-SEM, TEM and S-TEM. The vanadium element was found to be well-dispersed in the carbon nanofibers, free from the formation of an aggregated crystalline phase, even in the case of V20. A specific surface area of 587.9 m(2) g(-1) was reached for V10 after calcination, which is approximately twice that of the vanadium-free carbon nanofibers (V0, 300.9 m(2) g(-1)). To perform as an electrode for supercapacitors in an aqueous electrolyte, the V10 film delivered a specific capacitance of 463 F g(-1) at 1 A g(-1). V10 was also able to retain a specific capacitance of 380 F g(-1), even at a current density of 10 A g(-1). Additionally, very stable cycling stability was achieved, maintaining an outstanding specific capacitance of 400 F g(-1) at 5 A g(-1) after charge-discharge cycling 5000 times. Thus, V-O-C composite nanofibers are highly attractive electrode materials for flexible, high-power, thin film energy storage devices and applications.

Excellent capacitive performance of a three-dimensional hierarchical porous graphene/carbon composite with a superhigh surface area.

PubMed

Li, Xue Jin; Xing, Wei; Zhou, Jin; Wang, Gui Qiang; Zhuo, Shu Ping; Yan, Zi Feng; Xue, Qing Zhong; Qiao, Shi Zhang

2014-10-06

Three-dimensional hierarchical porous graphene/carbon composite was successfully synthesized from a solution of graphene oxide and a phenolic resin by using a facile and efficient method. The morphology, structure, and surface property of the composite were investigated intensively by a variety of means such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption, Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). It is found that graphene serves as a scaffold to form a hierarchical pore texture in the composite, resulting in its superhigh surface area of 2034 m(2) g(-1), thin macropore wall, and high conductivity (152 S m(-1)). As evidenced by electrochemical measurements in both EMImBF4 ionic liquid and KOH electrolyte, the composite exhibits ideal capacitive behavior, high capacitance, and excellent rate performance due to its unique structure. In EMImBF4 , the composite has a high energy density of up to 50.1 Wh kg(-1) and also possesses quite stable cycling stability at 100 °C, suggesting its promising application in high-temperature supercapacitors. In KOH electrolyte, the specific capacitance of this composite can reach up to an unprecedented value of 186.5 F g(-1), even at a very high current density of 50 A g(-1), suggesting its prosperous application in high-power applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbohydrazide-dependent reductant for preparing nitrogen-doped graphene hydrogels as electrode materials in supercapacitor

NASA Astrophysics Data System (ADS)

Jiang, Man; Xing, Ling-Bao; Zhang, Jing-Li; Hou, Shu-Fen; Zhou, Jin; Si, Weijiang; Cui, Hongyou; Zhuo, Shuping

2016-04-01

Three-dimensional (3D) nitrogen-doped graphene hydrogels (NGHs) are designed and synthesized in an efficient and fast way by using a strong reductant of carbohydrazide as reducing and doping agent in an aqueous solution of graphene oxide (GO). The transformation of GO suspension to the hydrogels can be completed in 1 h, which can be confirmed by X-ray powder diffraction (XRD), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). With adding different amounts of carbohydrazide, the obtained NGHs behave different doping of N and unlike performances in supercapacitors, which can be demonstrated by elemental analysis and X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), N2 sorption experiments, and electrochemical measurements, respectively. According to the network architectures, the NGHs all exhibited high specific capacitance, NGHs-1, NGHs-2, NGHs-5 and NGHs-10 showed specific capacitance at 167.7, 156.8, 140.4 and 119.3 F g-1 at 1 A g-1 in KOH electrolyte. The specific capacitance can still be maintained for 80.5, 79.5, 80.3 and 78.6% with an increase of the discharging current density of 10 A g-1, respectively. More interestingly, the NGHs-1 based supercapacitor also exhibited good electrochemical stability and high degree of reversibility in the long-term cycling test (81.5% retention after 4000 cycles).

Highly compressible reduced graphene oxide/polypyrrole/MnO2 aerogel electrodes meeting the requirement of limiting space

NASA Astrophysics Data System (ADS)

Lv, Peng; Tang, Xun; Yuan, Jiajiao; Ji, Chenglong

2017-11-01

Highly compressible electrodes are in high demand in volume-restricted energy storage devices. Superelastic reduced graphene oxide (rGO) aerogel with attractive characteristics are proposed as the promising skeleton for compressible electrodes. Herein, a ternary aerogel was prepared by successively electrodepositing polypyrrole (PPy) and MnO2 into the superelastic rGO aerogel. In the rGO/PPy/MnO2 aerogel, rGO aerogel provides the continuously conductive network; MnO2 is mainly responsible for pseudo reactions; the middle PPy layer not only reduces the interface resistance between rGO and MnO2, but also further enhanced the mechanical strength of rGO backbone. The synergistic effect of the three components leads to excellent performances including high specific capacitance, reversible compressibility, and extreme durability. The gravimetric capacitance of the compressible rGO/PPy/MnO2 aerogel electrodes reaches 366 F g-1 and can retain 95.3% even under 95% compressive strain. And a volumetric capacitance of 138 F cm-3 is achieved, which is much higher than that of other rGO-based compressible electrodes. This volumetric capacitance value can be preserved by 85% after 3500 charge/discharge cycles with various compression conditions. This work will pave the way for advanced applications in the area of compressible energy-storage devices meeting the requirement of limiting space.

Electrodeposition of nickel sulfide on graphene-covered make-up cotton as a flexible electrode material for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Li, Yiju; Ye, Ke; Cheng, Kui; Yin, Jinling; Cao, Dianxue; Wang, Guiling

2015-01-01

In this report, graphene nanosheets (GNS)/nickel sulfide (NiS) based material for high-performance supercapacitor is prepared by "dip and dry" and electrodeposition methods. Commercial flexible make-up cottons (MCs) are chose as skeletons to construct homogeneous three-dimensional (3D) interconnected graphene-wrapped macro-networks, which can support structures for high loading of active electrode materials and facilitate the access of electrolytes to active electrode materials. The hybrid GNS/NiS based MCs (denoted as MCs@GNS@NiS) electrode yields relatively high specific capacitance of 775 F g-1 at a charge/discharge specific current of 0.5 A g-1 and good capacitance retention of 88.1% after 1000 cycles at 2 A g-1. Furthermore, the MCs@GNS@NiS electrode delivers a high energy density of 11.2 Wh kg-1 at even a high power density of 1008 W kg-1. Therefore, such low-cost and high-performance energy MCs based on GNS/NiS hierarchical nanostructures offer great promise in large-scale energy storage device applications.

Converting Ni-loaded biochars into supercapacitors: Implication on the reuse of exhausted carbonaceous sorbents

NASA Astrophysics Data System (ADS)

Wang, Yifan; Zhang, Yue; Pei, Lei; Ying, Diwen; Xu, Xiaoyun; Zhao, Ling; Jia, Jinping; Cao, Xinde

2017-01-01

Biochar derived from waste biomass has proven as a promising sorbent for removal of heavy metals from wastewater. However, proper disposal of such a heavy metal-containing biochar is challengeable. The major objective of this study is to create a reuse way by converting the heavy metal-loaded biochar into supercapacitor. Two biochars were produced from dairy manure and sewage sludge, respectively, and subjected to sorption of Ni from solution, and then the Ni-loaded biochar underwent microwave treatments for fabrication of supercapacitor. The specific capacitance of biochar supercapacitor increased with Ni loading, especially the Ni-loaded biochar further treated with microwave in which the capacitance increased by over 2 times, compared to the original biochar supercapacitors. The increase of capacitance in the Ni-loaded biochar supercapacitor following microwave treatment was mainly attributed to the conversion of Ni into NiO and NiOOH, which was evidenced by X-ray diffraction and X-ray photoelectron spectroscopy. The biochar supercapacitors, especially microwave-treated Ni-loaded biochar supercapacitors exhibited the high stability of specific capacitance, with less than 2% loss after 1000 charge-discharge cycles. This study demonstrated that Ni-loaded biochar can be further utilized for generation of supercapacitor, providing a potential way for the reuse of exhausted carbonaceous sorbents.

Converting Ni-loaded biochars into supercapacitors: Implication on the reuse of exhausted carbonaceous sorbents

PubMed Central

Wang, Yifan; Zhang, Yue; Pei, Lei; Ying, Diwen; Xu, Xiaoyun; Zhao, Ling; Jia, Jinping; Cao, Xinde

2017-01-01

Biochar derived from waste biomass has proven as a promising sorbent for removal of heavy metals from wastewater. However, proper disposal of such a heavy metal-containing biochar is challengeable. The major objective of this study is to create a reuse way by converting the heavy metal-loaded biochar into supercapacitor. Two biochars were produced from dairy manure and sewage sludge, respectively, and subjected to sorption of Ni from solution, and then the Ni-loaded biochar underwent microwave treatments for fabrication of supercapacitor. The specific capacitance of biochar supercapacitor increased with Ni loading, especially the Ni-loaded biochar further treated with microwave in which the capacitance increased by over 2 times, compared to the original biochar supercapacitors. The increase of capacitance in the Ni-loaded biochar supercapacitor following microwave treatment was mainly attributed to the conversion of Ni into NiO and NiOOH, which was evidenced by X-ray diffraction and X-ray photoelectron spectroscopy. The biochar supercapacitors, especially microwave-treated Ni-loaded biochar supercapacitors exhibited the high stability of specific capacitance, with less than 2% loss after 1000 charge-discharge cycles. This study demonstrated that Ni-loaded biochar can be further utilized for generation of supercapacitor, providing a potential way for the reuse of exhausted carbonaceous sorbents. PMID:28128297

Graphene incorporated, N doped activated carbon as catalytic electrode in redox active electrolyte mediated supercapacitor

NASA Astrophysics Data System (ADS)

Gao, Zhiyong; Liu, Xiao; Chang, Jiuli; Wu, Dapeng; Xu, Fang; Zhang, Lingcui; Du, Weimin; Jiang, Kai

2017-01-01

Graphene incorporated, N doped activated carbons (GNACs) are synthesized by alkali activation of graphene-polypyrrole composite (G-PPy) at different temperatures for application as electrode materials of supercapacitors. Under optimal activation temperature of 700 °C, the resultant samples, labeled as GNAC700, owns hierarchically porous texture with high specific surface area and efficient ions diffusion channels, N, O functionalized surface with apparent pseudocapacitance contribution and high wettability, thus can deliver a moderate capacitance, a high rate capability and a good cycleability when used as supercapacitor electrode. Additionally, the GNAC700 electrode demonstrates high catalytic activity for the redox reaction of pyrocatechol/o-quinone pair in H2SO4 electrolyte, thus enables a high pseudocapacitance from electrolyte. Under optimal pyrocatechol concentration in H2SO4 electrolyte, the electrode capacitance of GNAC700 increases by over 4 folds to 512 F g-1 at 1 A g-1, an excellent cycleability is also achieved simultaneously. Pyridinic- N is deemed to be responsible for the high catalytic activity. This work provides a promising strategy to ameliorate the capacitive performances of supercapacitors via the synergistic interaction between redox-active electrolyte and catalytic electrodes.

Dilute NiO/carbon nanofiber composites derived from metal organic framework fibers as electrode materials for supercapacitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Ying; Yang, Feng; Hu, Hongru

A new type of carbon nanofiber (CNF) dominated electrode materials decorated with dilute NiO particles (NiO/CNF) has been in situ fabricated by direct pyrolysis of Ni, Zn-containing metal organic framework fibers, which are skillfully constructed by assembling different proportional NiCl2·6H2O and Zn(Ac)2·2H2O with trimesic acid in the presence of N,N-dimethylformamide. With elegant combination of advantages of CNF and evenly dispersed NiO particles, as well as successful modulation of conductivity and porosity of final composites, our NiO/CNF composites display well-defined capacitive features. A high capacitance of 14926 F g–1 was obtained in 6 M KOH electrolyte when the contribution from 0.43more » wt% NiO was considered alone, contributing to over 35% of the total capacitance (234 F g–1 ). This significantly exceeds its theoretical specific capacitance of 2584 F g–1. It has been established from the Ragone plot that a largest energy density of 33.4 Wh kg–1 was obtained at the current density of 0.25 A g–1. Furthermore, such composite electrode materials show good rate capability and outstanding cycling stability up to 5000 times (only 10% loss). The present study provides a brand-new approach to design a high capacitance and stable supercapacitor electrode and the concept is extendable to other composite materials. Keywords: Metal organic framework; Nickel oxide; Carbon nanofiber; In situ synthesis; Capacitance« less

Pseudocapacitive organic catechol derivative-functionalized three-dimensional graphene aerogel hybrid electrodes for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Choi, Jaewon; Yang, MinHo; Kim, Sung-Kon

2017-11-01

Bio-inspired and environmentally friendly chemical functionalization is a successful way to a new class of hybrid electrode materials for applications in energy storage. Quinone (Q)-hydroquinone (QH2) couples, a prototypical example of organic redox systems, provide fast and reversible proton-coupled electron-transfer reactions which lead to increased capacity. To achieve high capacitance and rate performance, constructing three-dimensional (3D) continuous porous structure is highly desirable. Here we report the hybrid electrodes (GA-C) consisting of 3D graphene aerogel (GA) functionalized with organic redox-active material, catechol derivative, for application to high-performance supercapacitors. The catechol derivative is adsorbed on the surface of GA through non-covalent interactions and promotes fast and reversible Q/QH2 faradaic reactions, providing large specific capacitance of 188 F g-1 at a current of 1 A g-1 and a specific energy of ∼25 Wh kg-1 at a specific power of ∼18,000 W kg-1. 3D continuous porous structure of GA electrode facilitates ion and electron transports, resulting in high rate performance (∼140 F g-1 at a current of 10 A g-1).

High performance aqueous symmetric supercapacitors based on advanced carbon electrodes and hydrophilic poly(vinylidene fluoride) porous separator

NASA Astrophysics Data System (ADS)

Xie, Qinxing; Huang, Xiaolin; Zhang, Yufeng; Wu, Shihua; Zhao, Peng

2018-06-01

The main components of a supercapacitor include two electrodes, electrolyte, and a separator, which are all essential to specify the energy storage capability of the device. In this work, two kinds of porous carbon materials have been fabricated via different routes using pomelo peel as raw material. The specific surface area are 1187 m2 g-1 for the nanosized worm-like carbon, and 1744 m2 g-1 for the nitrogen-enriched microsized carbon. Both carbon materials demonstrate excellent energy storage capability as electrodes for aqueous supercapacitors. According to the three-electrode measurements, the worm-like carbon exhibits a high specific capacitance of 316 F g-1 at 0.2 A g-1 in 6 M KOH, while the other exhibits 471 F g-1 due to the highly enriched nitrogen atoms in structure. In addition, two-electrode coin-type cells have been assembled with the carbon materials as electrodes and hydrophilic poly(vinylidene fluoride) porous membrane as the separator. The assembled cells exhibit high specific capacitances, excellent rate performance and superior cycling durability because of a synergistic effect of the high performance carbon electrodes and hydrophilic porous separator.

Decrease in the cytosolic NADP+-dependent isocitrate dehydrogenase activity through porcine sperm capacitation.

PubMed

Katoh, Yuki; Tamba, Michiko; Matsuda, Manabu; Kikuchi, Kazuhiro; Okamura, Naomichi

2018-02-26

In order to understand the molecular mechanisms involved in the sperm capacitation, we have identified the proteins tyrosine-phosphorylated during the capacitation especially in conjunction with the regulation of the levels of reactive oxygen species (ROS) in sperm. In the present study, the effects of the tyrosine phosphorylation of cytosolic NADP + -dependent isocitrate dehydrogenase (IDPc) on its catalytic activity and on the levels of ROS in sperm have been studied. The tyrosine phosphorylated IDPc showed a significantly lowered enzymatic activity. The immunocytochemical analyses using the highly specific antisera against IDPc revealed that IDPc was mainly localized to the principal piece of the porcine sperm flagellum. As IDPc is one of the major NADPH regenerating enzymes in porcine sperm, it is strongly suggested that the decrease in IDPc activity is involved in the increased levels of ROS, which results in the induction of hyperactivated flagellar movement and capacitation. Copyright © 2018 Elsevier Inc. All rights reserved.

Electrochemical properties of graphene nanosheets/polyaniline nanofibers composites as electrode for supercapacitors

NASA Astrophysics Data System (ADS)

Li, Jing; Xie, Huaqing; Li, Yang; Liu, Jie; Li, Zhuxin

Graphene nanosheets/polyaniline nanofibers (GNS/PANI) composites are synthesized via in situ polymerization of aniline monomer in HClO 4 solution. The PANI nanofibers homogeneously coating on the surface of GNS greatly improve the charge transfer reaction. The GNS/PANI composites exhibit better electrochemical performances than the pure individual components. A remarkable specific capacitance of 1130 F g -1 (based on GNS/PANI composites) is obtained at a scan rate of 5 mV s -1 in 1 M H 2SO 4 solution compared to 402 F g -1 for pure PANI and 270 F g -1 for GNS. The excellent performance is not only due to the GNS which can provide good electrical conductivity and high specific surface area, but also associate with a good redox activity of ordered PANI nanofibers. Moreover, the GNS/PANI composites present excellent long cycle life with 87% specific capacitance retained after 1000 charge/discharge processes. The resulting composites are promising electrode materials for high-performance electrical energy storage devices.

Electrode Mass Balancing as an Inexpensive and Simple Method to Increase the Capacitance of Electric Double-Layer Capacitors

PubMed Central

Andres, Britta; Engström, Ann-Christine; Blomquist, Nicklas; Forsberg, Sven; Dahlström, Christina; Olin, Håkan

2016-01-01

Symmetric electric double-layer capacitors (EDLCs) have equal masses of the same active material in both electrodes. However, having equal electrode masses may prevent the EDLC to have the largest possible specific capacitance if the sizes of the hydrated anions and cations in the electrolyte differ because the electrodes and the electrolyte may not be completely utilized. Here we demonstrate how this issue can be resolved by mass balancing. If the electrode masses are adjusted according to the size of the ions, one can easily increase an EDLC’s specific capacitance. To that end, we performed galvanostatic cycling to measure the capacitances of symmetric EDLCs with different electrode mass ratios using four aqueous electrolytes— Na2SO4, H2SO4, NaOH, and KOH (all with a concentration of 1 M)—and compared these to the theoretical optimal electrode mass ratio that we calculated using the sizes of the hydrated ions. Both the theoretical and experimental values revealed lower-than-1 optimal electrode ratios for all electrolytes except KOH. The largest increase in capacitance was obtained for EDLCs with NaOH as electrolyte. Specifically, we demonstrate an increase of the specific capacitance by 8.6% by adjusting the electrode mass ratio from 1 to 0.86. Our findings demonstrate that electrode mass balancing is a simple and inexpensive method to increase the capacitance of EDLCs. Furthermore, our results imply that one can reduce the amount of unused material in EDLCs and thus decrease their weight, volume and cost. PMID:27658253

Direct in situ measurement of specific capacitance, monolayer tension, and bilayer tension in a droplet interface bilayer

DOE PAGES

Taylor, Graham J.; Venkatesan, Guru A.; Collier, C. Patrick; ...

2015-08-05

In this study, thickness and tension are important physical parameters of model cell membranes. However, traditional methods to measure these quantities require multiple experiments using separate equipment. This work introduces a new multi-step procedure for directly accessing in situ multiple physical properties of droplet interface bilayers (DIB), including specific capacitance (related to thickness), lipid monolayer tension in the Plateau-Gibbs border, and bilayer tension. The procedure employs a combination of mechanical manipulation of bilayer area followed by electrowetting of the capacitive interface to examine the sensitivities of bilayer capacitance to area and contact angle to voltage, respectively. These data allow formore » determining the specific capacitance of the membrane and surface tension of the lipid monolayer, which are then used to compute bilayer thickness and tension, respectively. The use of DIBs affords accurate optical imaging of the connected droplets in addition to electrical measurements of bilayer capacitance, and it allows for reversibly varying bilayer area. After validating the accuracy of the technique with diphytanoyl phosphatidylcholine (DPhPC) DIBs in hexadecane, the method is applied herein to quantify separately the effects on membrane thickness and tension caused by varying the solvent in which the DIB is formed and introducing cholesterol into the bilayer. Because the technique relies only on capacitance measurements and optical images to determine both thickness and tension, this approach is specifically well-suited for studying the effects of peptides, biomolecules, natural and synthetic nanoparticles, and other species that accumulate within membranes without altering bilayer conductance.« less

Polypyrrole/titanium oxide nanotube arrays composites as an active material for supercapacitors.

PubMed

Kim, Min Seok; Park, Jong Hyeok

2011-05-01

The authors present the first reported use of vertically oriented titanium oxide nanotube/polypyrrole (PPy) nanocomposites to increase the specific capacitance of TiO2 based energy storage devices. To increase their electrical storage capacity, titanium oxide nanotubes were coated with PPy and their morphologies were characterized. The incorporation of PPy increased the specific capacitance of the titanium oxide nanotube based supercapacitor system, due to their increased surface area and additional pseudo-capacitance.

Hydrothermal synthesis of MnO2 thin film for supercapacitor application

NASA Astrophysics Data System (ADS)

Tarwate, Soni B.; Wahule, Swati S.; Gattu, Ketan P.; Ghule, Anil V.; Sharma, Ramphal

2018-05-01

MnO2 thin films were directly grown on stainless steel mesh via a facile hydrothermal method. The structural properties revealed the formation of delta MnO2. The capacitive performance of the as-obtained MnO2 electrode was evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge measurements. The synthesized electrode showed a high specific capacitance of 321 F g-1 at 5 A g-1. The excellent electrochemical performance identifies the MnO2 as a promising electrode material for next-generation energy storage devices.

High Mass Loading MnO2 with Hierarchical Nanostructures for Supercapacitors.

PubMed

Huang, Zi-Hang; Song, Yu; Feng, Dong-Yang; Sun, Zhen; Sun, Xiaoqi; Liu, Xiao-Xia

2018-04-24

Metal oxides have attracted renewed interest as promising electrode materials for high energy density supercapacitors. However, the electrochemical performance of metal oxide materials deteriorates significantly with the increase of mass loading due to their moderate electronic and ionic conductivities. This limits their practical energy. Herein, we perform a morphology and phase-controlled electrodeposition of MnO 2 with ultrahigh mass loading of 10 mg cm -2 on a carbon cloth substrate to achieve high overall capacitance without sacrificing the electrochemical performance. Under optimum conditions, a hierarchical nanostructured architecture was constructed by interconnection of primary two-dimensional ε-MnO 2 nanosheets and secondary one-dimensional α-MnO 2 nanorod arrays. The specific hetero-nanostructures ensure facile ionic and electric transport in the entire electrode and maintain the structure stability during cycling. The hierarchically structured MnO 2 electrode with high mass loading yields an outstanding areal capacitance of 3.04 F cm -2 (or a specific capacitance of 304 F g -1 ) at 3 mA cm -2 and an excellent rate capability comparable to those of low mass loading MnO 2 electrodes. Finally, the aqueous and all-solid asymmetric supercapacitors (ASCs) assembled with our MnO 2 cathode exhibit extremely high volumetric energy densities (8.3 mWh cm -3 at the power density of 0.28 W cm -3 for aqueous ASC and 8.0 mWh cm -3 at 0.65 W cm -3 for all-solid ASC), superior to most state-of-the-art supercapacitors.

Highly conductive electrospun carbon nanofiber/MnO2 coaxial nano-cables for high energy and power density supercapacitors

NASA Astrophysics Data System (ADS)

Zhi, Mingjia; Manivannan, Ayyakkannu; Meng, Fanke; Wu, Nianqiang

2012-06-01

This paper presents highly conductive carbon nanofiber/MnO2 coaxial cables in which individual electrospun carbon nanofibers are coated with an ultrathin hierarchical MnO2 layer. In the hierarchical MnO2 structure, an around 4 nm thick sheath surrounds the carbon nanofiber (CNF) in a diameter of 200 nm, and nano-whiskers grow radically outward from the sheath in view of the cross-section of the coaxial cables, giving a high specific surface area of MnO2. The CNFs are synthesized by electrospinning a precursor containing iron acetylacetonate (AAI). The addition of AAI not only enlarges the specific surface area of the CNF but also greatly enhances their electronic conductivity, which leads to a dramatic improvement in the specific capacitance and the rate capability of the CNF/MnO2 electrode. The AAI-CNF/MnO2 electrode shows a specific capacitance of 311 F g-1 for the whole electrode and 900 F g-1 for the MnO2 shell at a scan rate of 2 mV s-1. Good cycling stability, high energy density (80.2 Wh kg-1) and high power density (57.7 kW kg-1) are achieved. This work indicates that high electronic conductivity of the electrode material is crucial to achieving high power and energy density for pseudo-supercapacitors.

Chemical Synthesis of Sea-Urchin Shaped 3D-MnO2 Nano Structures and Their Application in Supercapacitors.

PubMed

Singu, Bal Sydulu; Hong, Sang Eun; Yoon, Kuk Ro

2016-06-01

Sea-urchin shaped α-MnO2 hierarchical nano structures have been synthesized by facile thermal method without using any hard or soft template under the mild conditions. The structural and morphology of the 3D-MnO2 was characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). From the XRD analysis indicates that MnO2 present in the α form. Morphology analysis shows that α-MnO2 sea-urchins are made by stacked nanorods, the diameter and length of the stacked nanorods present in the range of 50-120 nm and 200-400 nm respectively. The electrochemical behaviour of α-MnO2 has been investigated by cyclic voltammetry (CV) and charge-discharge (CD). The specific capacitance, energy density and power density are 212.0 F g(-1), 21.2 Wh kg(-1) and 1200 W kg(-1) respectively at the current density of 2 A g(-1). The retention of the specific capacitance after completion of 1000 charge-discharge cycles is around 97%. The results reveal that the prepared Sea-urchin shaped α-MnO2 has high specific capacitance and exhibit excellent cycle life.

Supercapacitors based on nitrogen-doped reduced graphene oxide and borocarbonitrides

NASA Astrophysics Data System (ADS)

Gopalakrishnan, K.; Moses, Kota; Govindaraj, A.; Rao, C. N. R.

2013-12-01

Nitrogen-doped reduced graphene oxide (RGO) samples with different nitrogen content, prepared by two different methods, as well as nitrogen-doped few-layer graphene have been investigated as supercapacitor electrodes. Two electrode measurements have been carried out both in aqueous (6M KOH) and in ionic liquid media. Nitrogen-doped reduced graphene oxides exhibit satisfactory specific capacitance, the values reaching 126F/g at a scan rate of 10mV/s in aqueous medium. Besides providing supercapacitor characteristics, the study has shown the nitrogen content and surface area to be important factors. High surface-area borocarbonitrides, BxCyNz, prepared by the urea route appear to be excellent supercapacitor electrode materials. Thus, BC4.5N exhibits a specific capacitance of 169F/g at a scan rate of 10mV/s in aqueous medium. In an ionic liquid medium, nitrogen-doped RGO and BC4.5N exhibit specific capacitance values of 258F/g and 240F/g at a scan rate of 5mV/s. The ionic liquid enables a larger operating voltage range of 0.0-2.5V compared to 0.0-1V in aqueous medium.

Highly flexible and all-solid-state paperlike polymer supercapacitors.

PubMed

Meng, Chuizhou; Liu, Changhong; Chen, Luzhuo; Hu, Chunhua; Fan, Shoushan

2010-10-13

In recent years, much effort have been dedicated to achieve thin, lightweight and even flexible energy-storage devices for wearable electronics. Here we demonstrate a novel kind of ultrathin all-solid-state supercapacitor configuration with an extremely simple process using two slightly separated polyaniline-based electrodes well solidified in the H(2)SO(4)-polyvinyl alcohol gel electrolyte. The thickness of the entire device is much comparable to that of a piece of commercial standard A4 print paper. Under its highly flexible (twisting) state, the integrate device shows a high specific capacitance of 350 F/g for the electrode materials, well cycle stability after 1000 cycles and a leakage current of as small as 17.2 μA. Furthermore, due to its polymer-based component structure, it has a specific capacitance of as high as 31.4 F/g for the entire device, which is more than 6 times that of current high-level commercial supercapacitor products. These highly flexible and all-solid-state paperlike polymer supercapacitors may bring new design opportunities of device configuration for energy-storage devices in the future wearable electronic area.

Multidimensional MnO2 nanohair-decorated hybrid multichannel carbon nanofiber as an electrode material for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Jun, Jaemoon; Lee, Jun Seop; Shin, Dong Hoon; Kim, Sung Gun; Jang, Jyongsik

2015-09-01

One-dimensional (1D)-structured nanomaterials represent one of the most attractive candidates for energy-storage systems due to their contribution to design simplicity, fast charge-transportation network, and their allowance for more accessible ion diffusion. In particular, 1D-structured nanomaterials with a highly complex inner-pore configuration enhance functionality by taking advantage of both the hollow and 1D structures. In this study, we report a MnO2 nanohair-decorated, hybrid multichannel carbon nanofiber (Mn_MCNF) fabricated via single-nozzle co-electrospinning of two immiscible polymer solutions, followed by carbonization and redox reactions. With improved ion accessibility, the optimized Mn_MCNF sample (Mn_MCNF_60 corresponding to a reaction duration time of 60 min for optimal MnO2 nanohair growth) exhibited a high specific capacitance of 855 F g-1 and excellent cycling performance with ~87.3% capacitance retention over 5000 cycles.One-dimensional (1D)-structured nanomaterials represent one of the most attractive candidates for energy-storage systems due to their contribution to design simplicity, fast charge-transportation network, and their allowance for more accessible ion diffusion. In particular, 1D-structured nanomaterials with a highly complex inner-pore configuration enhance functionality by taking advantage of both the hollow and 1D structures. In this study, we report a MnO2 nanohair-decorated, hybrid multichannel carbon nanofiber (Mn_MCNF) fabricated via single-nozzle co-electrospinning of two immiscible polymer solutions, followed by carbonization and redox reactions. With improved ion accessibility, the optimized Mn_MCNF sample (Mn_MCNF_60 corresponding to a reaction duration time of 60 min for optimal MnO2 nanohair growth) exhibited a high specific capacitance of 855 F g-1 and excellent cycling performance with ~87.3% capacitance retention over 5000 cycles. Electronic supplementary information (ESI) available: Experimental data includes optical images, TGA, magnified pore distribution curves and supercapacitor device of the MCNF and Mn_MCNF. See DOI: 10.1039/C5NR03616J

Synergistic interaction between pseudocapacitive Fe3O4 nanoparticles and highly porous silicon carbide for high-performance electrodes as electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Kim, Myeongjin; Kim, Jooheon

2017-05-01

Composites of micro- and mesoporous SiC flakes (SiCF) and ferroferric oxide (Fe3O4), SiCF/Fe3O4, were prepared via the chemical deposition of Fe3O4 on SiCF by the chemical reduction of an Fe precursor. The SiCF/Fe3O4 electrodes were fabricated at different Fe3O4 feeding ratios to determine the optimal Fe3O4 content that can maintain a high total surface area of SiCF/Fe3O4 composites as well as cause a vigorous redox reaction, thereby maximizing the synergistic effect between the electric double-layer capacitive effects of SiCF and the pseudo-capacitive effects of Fe3O4. The SiCF/Fe3O4 electrode fabricated with a Fe3O4/SiCF feeding ratio of 1.5:1 (SiCF/Fe3O4(1.5)) exhibited the highest charge storage capacity, showing a specific capacitance of 423.2 F g-1 at a scan rate of 5 mV s-1 with a rate performance of 81.8% from 5 to 500 mV s-1 in an aqueous 1 M KOH electrolyte. The outstanding capacitive performance of the SiCF/Fe3O4(1.5) electrode could be attributed to the harmonious synergistic effect between the electric double-layer capacitive contribution of the SiCF and the pseudocapacitive contribution of the Fe3O4 nanoparticles introduced on the SiCF surface. These encouraging results demonstrate that the SiCF/Fe3O4(1.5) electrode is a promising high-performance electrode material for use in supercapacitors.

Synergistic interaction between pseudocapacitive Fe3O4 nanoparticles and highly porous silicon carbide for high-performance electrodes as electrochemical supercapacitors.

PubMed

Kim, Myeongjin; Kim, Jooheon

2017-05-12

Composites of micro- and mesoporous SiC flakes (SiCF) and ferroferric oxide (Fe 3 O 4 ), SiCF/Fe 3 O 4 , were prepared via the chemical deposition of Fe 3 O 4 on SiCF by the chemical reduction of an Fe precursor. The SiCF/Fe 3 O 4 electrodes were fabricated at different Fe 3 O 4 feeding ratios to determine the optimal Fe 3 O 4 content that can maintain a high total surface area of SiCF/Fe 3 O 4 composites as well as cause a vigorous redox reaction, thereby maximizing the synergistic effect between the electric double-layer capacitive effects of SiCF and the pseudo-capacitive effects of Fe 3 O 4 . The SiCF/Fe 3 O 4 electrode fabricated with a Fe 3 O 4 /SiCF feeding ratio of 1.5:1 (SiCF/Fe 3 O 4 (1.5)) exhibited the highest charge storage capacity, showing a specific capacitance of 423.2 F g -1 at a scan rate of 5 mV s -1 with a rate performance of 81.8% from 5 to 500 mV s -1 in an aqueous 1 M KOH electrolyte. The outstanding capacitive performance of the SiCF/Fe 3 O 4 (1.5) electrode could be attributed to the harmonious synergistic effect between the electric double-layer capacitive contribution of the SiCF and the pseudocapacitive contribution of the Fe 3 O 4 nanoparticles introduced on the SiCF surface. These encouraging results demonstrate that the SiCF/Fe 3 O 4 (1.5) electrode is a promising high-performance electrode material for use in supercapacitors.

Layered manganese oxides-decorated and nickel foam-supported carbon nanotubes as advanced binder-free supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Huang, Ming; Mi, Rui; Liu, Hao; Li, Fei; Zhao, Xiao Li; Zhang, Wei; He, Shi Xuan; Zhang, Yu Xin

2014-12-01

Three-dimensional carbon nanotubes@MnO2 core-shell nanostructures grown on Ni foam for binder-free capacitor electrodes have been fabricated by a floating catalyst chemical vapor deposition process and a facile hydrothermal approach. Ultrathin layered MnO2 nanosheets are uniformly coated on the surface of the carbon nanotubes (CNTs), directly grown on Ni foam. This unique well-designed binder-free electrode exhibits a high specific capacitance (325.5 F g-1 at a current density of 0.3 A g-1), good rate capability (70.7% retention), and excellent cycling stability (90.5% capacitance retention after 5000 cycles), due to the high conductivity of the close contact between CNTs and Ni foam, as well as the moderate specific surface area of the CNTs@MnO2 core-shell nanostructures. The developed synthetic strategy may provide design guidelines for constructing advanced binder-free supercapacitors electrode.

High-performance super capacitors based on activated anthracite with controlled porosity

NASA Astrophysics Data System (ADS)

Lee, Hyun-Chul; Byamba-Ochir, Narandalai; Shim, Wang-Geun; Balathanigaimani, M. S.; Moon, Hee

2015-02-01

Mongolian anthracite is chemically activated using potassium hydroxide as an activation agent to make activated carbon materials. Prior to the chemical activation, the chemical agent is introduced by two different methods as follows, (1) simple physical mixing, (2) impregnation. The physical properties such as specific surface area, pore volume, pore size distribution, and adsorption energy distribution are measured to assess them as carbon electrode materials for electric double-layer capacitors (EDLC). The surface functional groups and morphology are also characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analyses respectively. The electrochemical results for the activated carbon electrodes in 3 M sulfuric acid electrolyte solution indicate that the activated Mongolian anthracite has relatively large specific capacitances in the range of 120-238 F g-1 and very high electrochemical stability, as they keep more than 98% of initial capacitances until 1000 charge/discharge cycles.

Hexagonal VS2 Anchored MWCNTs: First Approach to Design Flexible Solid-State Symmetric Supercapacitor Device.

PubMed

Pandit, Bidhan; Karade, Swapnil S; Sankapal, Babasaheb R

2017-12-27

Transition metal chalcogenides (TMCs) embedded with a carbon network are gaining much attention because of their high power capability, which can be easily integrated to portable electronic devices. Facile chemical route has been explored to synthesize hexagonal structured VS 2 nanoparticles onto multiwalled carbon nanotubes (MWCNTs) matrix. Such surface-modified VS 2 /MWCNTs electrode has boosted the electrochemical performance to reach high capacitance to 830 F/g and excellent stability to 95.9% over 10 000 cycles. Designed flexible solid-state symmetric supercapacitor device (FSSD) with a wide voltage window of 1.6 V exhibited maximum gain in specific capacitance value of 182 F/g at scan rate of 2 mV/s along with specific energy of 42 Wh/kg and a superb stability of 93.2% over 5000 cycles. As a practical approach, FSSD has lightened up "VNIT" panel consisting of 21 red LEDs.

The edge- and basal-plane-specific electrochemistry of a single-layer graphene sheet

PubMed Central

Yuan, Wenjing; Zhou, Yu; Li, Yingru; Li, Chun; Peng, Hailin; Zhang, Jin; Liu, Zhongfan; Dai, Liming; Shi, Gaoquan

2013-01-01

Graphene has a unique atom-thick two-dimensional structure and excellent properties, making it attractive for a variety of electrochemical applications, including electrosynthesis, electrochemical sensors or electrocatalysis, and energy conversion and storage. However, the electrochemistry of single-layer graphene has not yet been well understood, possibly due to the technical difficulties in handling individual graphene sheet. Here, we report the electrochemical behavior at single-layer graphene-based electrodes, comparing the basal plane of graphene to its edge. The graphene edge showed 4 orders of magnitude higher specific capacitance, much faster electron transfer rate and stronger electrocatalytic activity than those of graphene basal plane. A convergent diffusion effect was observed at the sub-nanometer thick graphene edge-electrode to accelerate the electrochemical reactions. Coupling with the high conductivity of a high-quality graphene basal plane, graphene edge is an ideal electrode for electrocatalysis and for the storage of capacitive charges. PMID:23896697

Junctionless Thin-Film Transistors Gated by an H₃PO₄-Incorporated Chitosan Proton Conductor.

PubMed

Liu, Huixuan; Xun, Damao

2018-04-01

We fabricated an H3PO4-incorporated chitosan proton conductor film that exhibited the electric double layer effect and showed a high specific capacitance of 4.42 μF/cm2. Transparent indium tin oxide thin-film transistors gated by H3PO4-incorporated chitosan films were fabricated by sputtering through a shadow mask. The operating voltage was as low as 1.2 V because of the high specific capacitance of the H3PO4-incorporated chitosan dielectrics. The junctionless transparent indium tin oxide thin film transistors exhibited good performance, including an estimated current on/off ratio and field-effect mobility of 1.2 × 106 and 6.63 cm2V-1s-1, respectively. These low-voltage thin-film electric-double-layer transistors gated by H3PO4-incorporated chitosan are promising for next generation battery-powered "see-through" portable sensors.

High-frequency carbon supercapacitors from polyfurfuryl alcohol

NASA Astrophysics Data System (ADS)

Ruiz, V.; Pandolfo, A. G.

Porous carbons with controllable and narrow pore-size distributions are prepared from the chemical activation of polyfurfuryl alcohol (PFA). High apparent BET surface areas, up to 2600 m 2 g -1 (2611 m 2 g -1 by Density Functional Theory (DFT)), and good electrical conductivities (up to ∼130 S cm -1) are obtained. By varying the potassium hydroxide: carbon precursor ratio, the preparation of carbons with different proportions of micro- and fine mesoporosity (<5 nm) can be tailored to provide an ideal electronic and ionic pore structure for electrochemical energy-storage devices, such as electrical double-layer capacitors. High specific capacitance values are obtained up to 147 F g -1 in a voltage window of 2.5 V using 1 M tetraethyl ammonium tetrafluoroborate in acetonitrile. Moreover, excellent high-current and high-frequency performance is demonstrated: 100 F g -1 at 225 A g -1 (10 Hz) and ∼30 F g -1 at 100 Hz. When comparing the performance with commercial activated carbons (ACs) of similar textural properties, the PFA-derived ACs demonstrated better performance in terms of higher capacitance values and improved rate capabilities. There is a 125% increase in capacitance values at 1 kHz.

Anodic composite deposition of RuO2/reduced graphene oxide/carbon nanotube for advanced supercapacitors

NASA Astrophysics Data System (ADS)

Hu, Chi-Chang; Wang, Chia-Wei; Chang, Kuo-Hsin; Chen, Ming-Guan

2015-07-01

Anodic composite deposition is demonstrated to be a unique method for fabricating a ternary ruthenium dioxide/reduced graphene oxide/carbon nanotube (RuO2 · xH2O/rGO/CNT, denoted as RGC) nanocomposite onto Ti as an advanced electrode material for supercapacitors. The rGO/CNT composite in RGCs acts as a conductive backbone to facilitate the electron transport between current collector and RuO2 · xH2O nanoparticles (NPs), revealed by the high total specific capacitance (CS,T = 808 F g-1) of RGC without annealing. The contact resistance among RuO2 · xH2O NPs is improved by low-temperature annealing at 150 °C (RGC-150), which renders slight sintering and enhances the specific capacitance of RuO2 · xH2O to achieve 1200 F g-1. The desirable nanocomposite microstructure of RGC-150 builds up the smooth pathways of both protons and electrons to access the active oxy-ruthenium species. This nanocomposite exhibits an extremely high CS,T of 973 F g-1 at 25 mV s-1 (much higher than 435 F g-1 of an annealed RuO2 · xH2O deposit) and good capacitance retention (60.5% with scan rate varying from 5 to 500 mV s-1), revealing an advanced electrode material for high-performance supercapacitors.

Anodic composite deposition of RuO₂/reduced graphene oxide/carbon nanotube for advanced supercapacitors.

PubMed

Hu, Chi-Chang; Wang, Chia-Wei; Chang, Kuo-Hsin; Chen, Ming-Guan

2015-07-10

Anodic composite deposition is demonstrated to be a unique method for fabricating a ternary ruthenium dioxide/reduced graphene oxide/carbon nanotube (RuO2 xH2O/rGO/CNT, denoted as RGC) nanocomposite onto Ti as an advanced electrode material for supercapacitors. The rGO/CNT composite in RGCs acts as a conductive backbone to facilitate the electron transport between current collector and RuO2 xH2O nanoparticles (NPs), revealed by the high total specific capacitance (C(S,T) = 808 F g(-1)) of RGC without annealing. The contact resistance among RuO2 xH2O NPs is improved by low-temperature annealing at 150 °C (RGC-150), which renders slight sintering and enhances the specific capacitance of RuO2 xH2O to achieve 1200 F g(-1). The desirable nanocomposite microstructure of RGC-150 builds up the smooth pathways of both protons and electrons to access the active oxy-ruthenium species. This nanocomposite exhibits an extremely high C(S,T) of 973 F g(-1) at 25 mV s(-1) (much higher than 435 F g(-1) of an annealed RuO2 xH2O deposit) and good capacitance retention (60.5% with scan rate varying from 5 to 500 mV s(-1)), revealing an advanced electrode material for high-performance supercapacitors.

Asymmetric supercapacitors based on functional electrospun carbon nanofiber/manganese oxide electrodes with high power density and energy density

NASA Astrophysics Data System (ADS)

Lin, Sheng-Chi; Lu, Yi-Ting; Chien, Yu-An; Wang, Jeng-An; You, Ting-Hsuan; Wang, Yu-Sheng; Lin, Chih-Wen; Ma, Chen-Chi M.; Hu, Chi-Chang

2017-09-01

Carbon nanofibers modified with carboxyl groups (CNF-COOH) possessing good wettability and high porosity are homogeneously deposited with amorphous manganese dioxide (amorphous MnO2) by potentiodynamic deposition for asymmetric super-capacitors (ASCs). The potential-cycling in 1 M H2SO4 successfully enhances the hydrophilicity of carbonized polymer nanofibers and facilitates the access of electrolytes within the CNF-COOH matrix. This modification favors the deposition of amorphous MnO2 and improves its electrochemical utilization. In this composite, MnO2 homogeneously dispersed onto CNF-COOH provides desirable pseudocapacitance and the CNF-COOH network works as the electron conductor. The composite of CNF-COOH@MnO2-20 shows a high specific capacitance of 415 F g-1 at 5 mV s-1. The capacitance retention of this composite is 94% in a 10,000-cycle test. An ASC cell consisting of this composite and activated carbon as positive and negative electrodes can be reversibly charged/discharged to a cell voltage of 2.0 V in 1 M Na2SO4 and 4 mM NaHCO3 with specific energy and power of 36.7 Wh kg-1 and 354.9 W kg-1, respectively. This ASC also shows excellent cell capacitance retention (8% decay) in the 2V, 10,000-cycle stability test, revealing superior performance.

Self-assembling graphene-anthraquinone-2-sulphonate supramolecular nanostructures with enhanced energy density for supercapacitors.

PubMed

Gao, Lifang; Gan, Shiyu; Li, Hongyan; Han, Dongxue; Li, Fenghua; Bao, Yu; Niu, Li

2017-07-07

Boosting the energy density of capacitive energy storage devices remains a crucial issue for facilitating applications. Herein, we report a graphene-anthraquinone supramolecular nanostructure by self-assembly for supercapacitors. The sulfonated anthraquinone exhibits high water solubility, a π-conjugated structure and redox active features, which not only serve as a spacer to interact with and stabilize graphene but also introduce extra pseudocapacitance contributions. The formed nest-like three-dimensional (3D) nanostructure with further hydrothermal treatment enhances the accessibility of ion transfer and exposes the redox-active quinone groups in the electrolytes. A fabricated all-solid-state flexible symmetric device delivers a high specific capacitance of 398.5 F g -1 at 1 A g -1 (1.5 times higher than graphene), superior energy density (52.24 Wh kg -1 at about 1 kW kg -1 ) and good stability (82% capacitance retention after 10 000 cycles).

Anomalous or regular capacitance? The influence of pore size dispersity on double-layer formation

NASA Astrophysics Data System (ADS)

Jäckel, N.; Rodner, M.; Schreiber, A.; Jeongwook, J.; Zeiger, M.; Aslan, M.; Weingarth, D.; Presser, V.

2016-09-01

The energy storage mechanism of electric double-layer capacitors is governed by ion electrosorption at the electrode surface. This process requires high surface area electrodes, typically highly porous carbons. In common organic electrolytes, bare ion sizes are below one nanometer but they are larger when we consider their solvation shell. In contrast, ionic liquid electrolytes are free of solvent molecules, but cation-anion coordination requires special consideration. By matching pore size and ion size, two seemingly conflicting views have emerged: either an increase in specific capacitance with smaller pore size or a constant capacitance contribution of all micro- and mesopores. In our work, we revisit this issue by using a comprehensive set of electrochemical data and a pore size incremental analysis to identify the influence of certain ranges in the pore size distribution to the ion electrosorption capacity. We see a difference in solvation of ions in organic electrolytes depending on the applied voltage and a cation-anion interaction of ionic liquids in nanometer sized pores.

Capacitive malaria aptasensor using Plasmodium falciparum glutamate dehydrogenase as target antigen in undiluted human serum.

PubMed

Singh, Naveen K; Arya, Sunil K; Estrela, Pedro; Goswami, Pranab

2018-06-08

A capacitive aptasensor for detecting the malaria biomarker, Plasmodium falciparum glutamate dehydrogenase (PfGDH), directly in human serum samples developed. A thiolated ssDNA aptamer (NG3) that binds specifically to PfGDH antigen with high affinity (K d = 79 nM) was used to develop the aptasensor. The aptasensor produced capacitance response at an optimized frequency of 2 Hz in a non-Faradaic electrochemical impedance based signal transduction platform. The aptasensor exhibited a wide dynamic range of 100 fM-100 nM with a limits of detection of 0.77 pM in serum samples. The interference from other predominant malarial biomarkers, namely, Plasmodium falciparum -lactate dehydrogenase and -histidine rich protein-II on the aptasensor was negligible. This PfGDH aptasensor with highly sensitive and label free detection capability has great application potential for diagnosis of asymptotic malaria and monitoring the regression of malaria during treatment regime with antimalarial drugs. Copyright © 2018 Elsevier B.V. All rights reserved.

Significance of the double-layer capacitor effect in polar rubbery dielectrics and exceptionally stable low-voltage high transconductance organic transistors.

PubMed

Wang, Chao; Lee, Wen-Ya; Kong, Desheng; Pfattner, Raphael; Schweicher, Guillaume; Nakajima, Reina; Lu, Chien; Mei, Jianguo; Lee, Tae Hoon; Wu, Hung-Chin; Lopez, Jeffery; Diao, Ying; Gu, Xiaodan; Himmelberger, Scott; Niu, Weijun; Matthews, James R; He, Mingqian; Salleo, Alberto; Nishi, Yoshio; Bao, Zhenan

2015-12-14

Both high gain and transconductance at low operating voltages are essential for practical applications of organic field-effect transistors (OFETs). Here, we describe the significance of the double-layer capacitance effect in polar rubbery dielectrics, even when present in a very low ion concentration and conductivity. We observed that this effect can greatly enhance the OFET transconductance when driven at low voltages. Specifically, when the polar elastomer poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVDF-HFP) was used as the dielectric layer, despite a thickness of several micrometers, we obtained a transconductance per channel width 30 times higher than that measured for the same organic semiconductors fabricated on a semicrystalline PVDF-HFP with a similar thickness. After a series of detailed experimental investigations, we attribute the above observation to the double-layer capacitance effect, even though the ionic conductivity is as low as 10(-10) S/cm. Different from previously reported OFETs with double-layer capacitance effects, our devices showed unprecedented high bias-stress stability in air and even in water.

Hydrothermally Activated Graphene Fiber Fabrics for Textile Electrodes of Supercapacitors.

PubMed

Li, Zheng; Huang, Tieqi; Gao, Weiwei; Xu, Zhen; Chang, Dan; Zhang, Chunxiao; Gao, Chao

2017-11-28

Carbon textiles are promising electrode materials for wearable energy storage devices owing to their conductive, flexible, and lightweight features. However, there still lacks a perfect choice for high-performance carbon textile electrodes with sufficient electrochemical activity. Graphene fiber fabrics (GFFs) are newly discovered carbon textiles, exhibiting various attractive properties, especially a large variability on the microstructure. Here we report the fabrication of hierarchical GFFs with significantly enlarged specific surface area using a hydrothermal activation strategy. By carefully optimize the activation process, the hydrothermally activated graphene fiber fabrics (HAGFFs) could achieve an areal capacitance of 1060 mF cm -2 in a very thin thickness (150 μm) and the capacitance is easily magnified by overlaying several layers of HAGFFs, even up to a record value of 7398 mF cm -2 . Meanwhile, a good rate capability and a long cycle life are also attained. As compared with other carbon textiles, including the commercial carbon fiber cloths, our HAGFFs present much better capacitive performance. Therefore, the mechanically stable, flexible, conductive, and highly active HAGFFs have provided an option for high-performance textile electrodes.

Significance of the double-layer capacitor effect in polar rubbery dielectrics and exceptionally stable low-voltage high transconductance organic transistors

PubMed Central

Wang, Chao; Lee, Wen-Ya; Kong, Desheng; Pfattner, Raphael; Schweicher, Guillaume; Nakajima, Reina; Lu, Chien; Mei, Jianguo; Lee, Tae Hoon; Wu, Hung-Chin; Lopez, Jeffery; Diao, Ying; Gu, Xiaodan; Himmelberger, Scott; Niu, Weijun; Matthews, James R.; He, Mingqian; Salleo, Alberto; Nishi, Yoshio; Bao, Zhenan

2015-01-01

Both high gain and transconductance at low operating voltages are essential for practical applications of organic field-effect transistors (OFETs). Here, we describe the significance of the double-layer capacitance effect in polar rubbery dielectrics, even when present in a very low ion concentration and conductivity. We observed that this effect can greatly enhance the OFET transconductance when driven at low voltages. Specifically, when the polar elastomer poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVDF-HFP) was used as the dielectric layer, despite a thickness of several micrometers, we obtained a transconductance per channel width 30 times higher than that measured for the same organic semiconductors fabricated on a semicrystalline PVDF-HFP with a similar thickness. After a series of detailed experimental investigations, we attribute the above observation to the double-layer capacitance effect, even though the ionic conductivity is as low as 10–10 S/cm. Different from previously reported OFETs with double-layer capacitance effects, our devices showed unprecedented high bias-stress stability in air and even in water. PMID:26658331

Layer-dependent supercapacitance of graphene films grown by chemical vapor deposition on nickel foam

NASA Astrophysics Data System (ADS)

Chen, Wei; Fan, Zhongli; Zeng, Gaofeng; Lai, Zhiping

2013-03-01

High-quality, large-area graphene films with few layers are synthesized on commercial nickel foams under optimal chemical vapor deposition conditions. The number of graphene layers is adjusted by varying the rate of the cooling process. It is found that the capacitive properties of graphene films are related to the number of graphene layers. Owing to the close attachment of graphene films on the nickel substrate and the low charge-transfer resistance, the specific capacitance of thinner graphene films is almost twice that of the thicker ones and remains stable up to 1000 cycles. These results illustrate the potential for developing high-performance graphene-based electrical energy storage devices.

Carbon nanocages as supercapacitor electrode materials.

PubMed

Xie, Ke; Qin, Xingtai; Wang, Xizhang; Wang, Yangnian; Tao, Haisheng; Wu, Qiang; Yang, Lijun; Hu, Zheng

2012-01-17

Supercapacitor electrode materials: Carbon nanocages are conveniently produced by an in situ MgO template method and demonstrate high specific capacitance over a wide range of charging-discharging rates with high stability, superior to the most carbonaceous supercapacitor electrode materials to date. The large specific surface area, good mesoporosity, and regular structure are responsible for the excellent performance. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Co3O4 nanowire@NiO nanosheet arrays for high performance asymmetric supercapacitors.

PubMed

Xing, Lei; Dong, Yidi; Hu, Fang; Wu, Xiang; Umar, Ahmad

2018-04-24

Herein, we report a simple and facile sequential hydrothermal process for the synthesis of Co3O4 nanowire@NiO nanosheet arrays (CNAs). The as-synthesized CNAs were characterized in detail using various analytical techniques, which confirmed the high crystallinity, purity, and high-density growth of these nanomaterials. From an application point of view, the as-synthesized CNAs were directly used as supercapacitor electrodes, revealing a specific capacitance of up to 2018 mF cm-2 at a current density of 2 mA cm-2. Furthermore, a flexible asymmetric supercapacitor was fabricated using the as-synthesized CNAs as the anode and activated carbon as the cathode, which revealed a specific capacitance of 134.6 mF cm-2 at a current density of 2 mA cm-2. In addition, the supercapacitor showed excellent capacity retention of 73.5% after 10 000 cycles at a current density of 10 mA cm-2.

Three-dimensional reduced-graphene/MnO2 prepared by plasma treatment as high-performance supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Liu, Runru; Wen, Dongdong; Zhang, Xueyu; Wang, Dejun; Yang, Qiang; Yuan, Beilei; Lü, Wei

2018-06-01

In this work, three-Dimensional nitrogen-doped graphene/MnO2 (NG/MnO2) was prepared by plasma treatment, which provides a high specific surface area due to porous structure and exhibits enhanced supercapacitor performance. The advantage of NG/MnO2 electrode was obvious compared with reduced graphene oxide/MnO2 (RGO/MnO2) which was prepared by traditional hydrothermal method, such as improved electrochemical property and better cycling stability. The specific capacitance of NG/MnO2 at the scan rate of 5 mV s‑1 (393 F g‑1) is higher than that of RGO/MnO2 (260 F g‑1). In addition, NG/MnO2 showed higher durability with 90.2% capacitance retention than that of RGO/MnO2 (82%) after 5000 cycles. Such cheap and high-performance supercapacitor electrodes are available by our feasible plasma treatment, which give promise in large-scale commercial energy storage devices.

High-Performance Supercapacitor Electrode Materials from Cellulose-Derived Carbon Nanofibers.

PubMed

Cai, Jie; Niu, Haitao; Li, Zhenyu; Du, Yong; Cizek, Pavel; Xie, Zongli; Xiong, Hanguo; Lin, Tong

2015-07-15

Nitrogen-functionalized carbon nanofibers (N-CNFs) were prepared by carbonizing polypyrrole (PPy)-coated cellulose NFs, which were obtained by electrospinning, deacetylation of electrospun cellulose acetate NFs, and PPy polymerization. Supercapacitor electrodes prepared from N-CNFs and a mixture of N-CNFs and Ni(OH)2 showed specific capacitances of ∼236 and ∼1045 F g(-1), respectively. An asymmetric supercapacitor was further fabricated using N-CNFs/Ni(OH)2 and N-CNFs as positive and negative electrodes. The supercapacitor device had a working voltage of 1.6 V in aqueous KOH solution (6.0 M) with an energy density as high as ∼51 (W h) kg(-1) and a maximum power density of ∼117 kW kg(-1). The device had excellent cycle lifetime, which retained ∼84% specific capacitance after 5000 cycles of cyclic voltammetry scans. N-CNFs derived from electrospun cellulose may be useful as an electrode material for development of high-performance supercapacitors and other energy storage devices.

Facile electrodeposition of reduced graphene oxide hydrogels for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Pham, Viet Hung; Gebre, Tesfaye; Dickerson, James H.

2015-03-01

We report both a facile, scalable method to prepare reduced graphene oxide hydrogels through the electrodeposition of graphene oxide and its use as an electrode for high-performance supercapacitors. Such systems exhibited specific capacitances of 147 and 223 F g-1 at a current density of 10 A g-1 when using H2SO4 and H2SO4 + hydroquinone redox electrolytes, respectively.We report both a facile, scalable method to prepare reduced graphene oxide hydrogels through the electrodeposition of graphene oxide and its use as an electrode for high-performance supercapacitors. Such systems exhibited specific capacitances of 147 and 223 F g-1 at a current density of 10 A g-1 when using H2SO4 and H2SO4 + hydroquinone redox electrolytes, respectively. Electronic supplementary information (ESI) available: GO synthesis, characterization, fabrication of ERGO supercapacitor and electrochemical measurement, elemental composition, TGA and XRD of GO and ERGO. See DOI: 10.1039/c4nr07508k

Pomelo peels-derived porous activated carbon microsheets dual-doped with nitrogen and phosphorus for high performance electrochemical capacitors

NASA Astrophysics Data System (ADS)

Wang, Zhen; Tan, Yongtao; Yang, Yunlong; Zhao, Xiaoning; Liu, Ying; Niu, Lengyuan; Tichnell, Brandon; Kong, Lingbin; Kang, Long; Liu, Zhen; Ran, Fen

2018-02-01

In this work, biomass pomelo peel is used to fabricate the porous activated carbon microsheets, and diammonium hydrogen phosphate (DHP) is employed to dual-dope carbon with nitrogen and phosphorus elements. With the benefit of DHP inducement and dual-doping of nitrogen and phosphorus, the prepared carbon material has a higher carbon yield, and exhibits higher specific surface area (about 807.7 m2/g), and larger pore volume (about 0.4378 cm3/g) with hierarchically structure of interconnected thin microsheets compared to the pristine carbon. The material exhibits not only high specific capacitance (240 F/g at 0.5 A/g), but also superior cycling performance (approximately 100% of capacitance retention after 10,000 cycles at 2 A/g) in 2 M KOH aqueous electrolyte. Furthermore, the assembled symmetric electrochemical capacitor in 1 M Na2SO4 aqueous electrolyte exhibits a high energy density of 11.7 Wh/kg at a power density of 160 W/kg.

Polyaniline nanofibers with a high specific surface area and an improved pore structure for supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Hailing; Li, Xingwei; Wang, Gengchao

2015-10-01

Polyaniline (PANI) with a high specific surface area and an improved pore structure (HSSA-PANI) has been prepared by using a facile method, treating PANI nanofibers with chloroform (CHCl3), and its structure, morphology and pore structure are investigated. The specific surface area and pore volume of HSSA-PANI are 817.3 m2 g-1 and 0.6 cm3 g-1, and those of PANI are 33.6 m2 g-1 and 0.2 cm3 g-1. As electrode materials, a large specific surface area and pore volume can provide high electroactive regions, accelerate the diffusion of ions, and mitigate the electrochemical degradation of active materials. Compared with PANI, the capacity retention rate of HSSA-PANI is 90% with a growth of current density from 5.0 to 30 A g-1, and that of PANI is 29%. At a current density of 30 A g-1, the specific capacitance of HSSA-PANI still reaches 278.3 F g-1, and that of PANI is 86.7 F g-1. At a current density of 5.0 A g-1, the capacitance retention of HSSA-PANI is 53.1% after 2000 cycles, and that of PANI electrode is only 28.1%.

Seaurchin-like hierarchical NiCo2O4@NiMoO4 core-shell nanomaterials for high performance supercapacitors.

PubMed

Zhang, Qiang; Deng, Yanghua; Hu, Zhonghua; Liu, Yafei; Yao, Mingming; Liu, Peipei

2014-11-14

A novel electrode material of the three-dimensional (3D) multicomponent oxide NiCo2O4@NiMoO4 core-shell was synthesized via a facile two-step hydrothermal method using a post-annealing procedure. The uniform NiMoO4 nanosheets were grown on the seaurchin-like NiCo2O4 backbone to form a NiCo2O4@NiMoO4 core-shell material constructed by interconnected ultrathin nanosheets, so as to produce hierarchical mesopores with a large specific surface area of 100.3 m(2) g(-1). The porous feature and core-shell structure can facilitate the penetration of electrolytic ions and increases the number of electroactive sites. Hence, the NiCo2O4@NiMoO4 material exhibited a high specific capacitance of 2474 F g(-1) and 2080 F g(-1) at current densities of 1 A g(-1) and 20 A g(-1) respectively, suggesting that it has not only a very large specific capacitance, but also a good rate performance. In addition, the capacitance loss was only 5.0% after 1000 cycles of charge and discharge tests at the current density of 10 A g(-1), indicating high stability. The excellent electrochemical performance is mainly attributed to its 3D core-shell and hierarchical mesoporous structures which can provide unobstructed pathways for the fast diffusion and transportation of ions and electrons, a large number of active sites and good strain accommodation.

A core–shell structured nanocomposite of NiO with carbon nanotubes as positive electrode material of high capacitance for supercapacitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Z.B., E-mail: zbwen@jxnu.edu.cn; Yu, F.; College of Energy, Nanjing Tech University, Nanjing 211816, Jiangsu Province

2016-02-15

Highlights: • A core–shell structured NiO@CNTs nanocomposite is synthesized by a simple hydrothermal method. • The CNTs core effectively improves the capacitance, rate and cycling performance of NiO. • A supercapacitor is assembled when activated carbon is used as the negative electrode. • The supercapacitor presents an energy density up to 52.6 Wh kg{sup −1}. - Abstract: A nanocomposite of carbon nanotubes coated with nickel oxide was prepared by a simple hydrothermal method. The structure, morphology and electrochemical performance of the nanocomposite were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, electrochemical tests including cyclic voltammogram, galvanostaticmore » charge–discharge and electrochemical impedance spectroscopy, respectively. It presents the highest specific capacitance of 1844 F g{sup −1} at 1 A g{sup −1} and 1145 F g{sup −1} at current density of 10 A g{sup −1} with 88.9% (at 1 A g{sup −1}) capacitance retention after 1000 cycles. The specific capacitance of the nanocomposite is almost double of that of the virginal NiO (972 F g{sup −1} at 1 A g{sup −1}). Its cycling behavior is also very good. When combined with activated carbon as the negative electrode, the energy density can be up to 52.6 Wh kg{sup −1}. Such good electrochemical behavior indicates that the nanocomposite is a promising electrode material for supercapacitors.« less

Electrochemical double-layer capacitors based on functionalized graphene

NASA Astrophysics Data System (ADS)

Pope, Michael Allan

Graphene is a promising electrode material for electrochemical double-layer capacitors (EDLCs) used for energy storage due to its high electrical conductivity and theoretical specific surface area. However, the intrinsic capacitance of graphene is known to be low and governed by the electronic side of the interface. Furthermore, graphene tends to aggregate and stack together when processed into thick electrode films. This significantly lowers the ion-accessible specific surface area (SSA). Maximizing both the SSA and the intrinsic capacitance are the main problems addressed in this thesis in an effort to improve the specific capacitance and energy density of EDLCs. In contrast to pristine graphene, functionalized graphene produced by the thermal exfoliation of graphite oxide contains residual functional groups and lattice defects. To study how these properties affect the double-layer capacitance, a model electrode system capable of measuring the intrinsic electrochemical properties of functionalized graphene was developed. To prevent artifacts and uncertainties related to measurements on porous electrodes, the functionalized graphene sheets (FGSs) were assembled as densely tiled monolayers using a Langmuir-Blodgett technique. In this way, charging can be studied in a well-defined 2D geometry. The possibility of measuring and isolating the intrinsic electrochemical properties of FGS monolayers was first demonstrated by comparing capacitance and redox probe measurements carried out on coatings deposited on passivated gold and single crystal graphite substrates. This monolayer system was then used to follow the double-layer capacitance of the FGS/electrolyte interface as the structure and chemistry of graphene was varied by thermal treatments ranging from 300 °C to 2100 °C. Elemental analysis and Raman spectroscopy were used to determine the resulting chemical and structural transformation upon heat treatment. It was demonstrated that intrinsically defective graphene monolayers can exhibit four-fold higher double-layer capacitance than pristine graphene. High temperature annealing lowered the capacitance until it approached that of pristine graphene. An optimal level of functionalization and lattice disorder is found necessary to retain high double-layer capacitance suggesting that graphene-based materials can be chemically tailored to engineer higher capacitance electrodes. The second half of this thesis focuses on understanding the factors that control the SSA of FGS aggregates when processed into dense electrodes and the development of a new electrode fabrications strategy to improve the ion-accessible surface area of FGS-based electrodes. Using various processing conditions, it was demonstrated that aggregates can exhibit a wide range of SSAs (1 m 2/g to 1750 m2/g) accessible to the adsorption of nitrogen or methylene blue. The effects of capillary forces, van der Waals interactions and aggregation kinetics on the SSA were explored and an aggregation model was proposed to account for these effects. In order to minimize aggregation, a new strategy for preparing graphene-based electrodes for EDLCs was developed. Colloidal gels of graphene oxide in a water-ethanol-ionic liquid solution were assembled into graphene-ionic liquid laminated structures. Our process involves evaporating the solvents water and ethanol yielding a graphene oxide/ionic liquid composite, followed by thermal reduction of the graphene oxide to electrically conducting functionalized graphene. This yields an electrode in which the ionic liquid serves not only as the working electrolyte but also as a spacer to separate the graphene sheets and to increase their electrolyte-accessible surface area. Using this approach, we achieve an outstanding energy density of 17.5 Wh/kg at a gravimetric capacitance of 156 F/g and 3 V operating voltage, due to a high effective density of the active electrode material of 0.46 g/cm2. By increasing the ionic liquid content and degree of thermal reduction, we obtain electrodes that retain >90% of their capacity at a scan rate of 500 mV/s, illustrating that we can tailor the electrodes towards higher power density if energy density is not the primary goal. The ease of manufacturing, achieved by combining the steps of electrode assembly and electrolyte infiltration, makes this bottom-up assembly approach scalable and well suited for combinations of potentially any graphene material with ionic liquid electrolytes.

An Asymmetric Supercapacitor with Mesoporous NiCo2O4 Nanorod/Graphene Composite and N-Doped Graphene Electrodes

NASA Astrophysics Data System (ADS)

Mao, J. W.; He, C. H.; Qi, J. Q.; Zhang, A. B.; Sui, Y. W.; He, Y. Z.; Meng, Q. K.; Wei, F. X.

2018-01-01

In the present work, mesoporous NiCo2O4 nanorod/graphene oxide (NiCo2O4/GO) composite was prepared by a facile and cost-effective hydrothermal method and meanwhile, N-doped graphene (N-G) was fabricated also by a hydrothermal synthesis process. NiCo2O4/GO composite and N-G were used as positive and negative electrodes for the supercapacitor, respectively, which all displayed excellent electrochemical performances. The NiCo2O4/GO composite electrode exhibited a high specific capacitance of 709.7 F g-1 at a current density of 1 A g-1 and excellent rate capability as well as good cycling performance with 84.7% capacitance retention at 6 A g-1 after 3000 cycles. A high-voltage asymmetric supercapacitor (ASC) was successfully fabricated using NiCo2O4/GO composite and N-G as the positive and negative electrodes, respectively, in 1 M KOH aqueous electrolyte. The ASC delivered a high energy density of 34.4 Wh kg-1 at a power density of 800 W kg-1 and still maintained 28 Wh kg-1 at a power density of 8000 W kg-1. Furthermore, this ASC showed excellent cycling stability with 94.3% specific capacitance retained at 5 A g-1 after 5000 cycles. The impressive results can be ascribed to the positive synergistic effects of the two electrodes. Evidently, our work provides useful information for assembling high-performance supercapacitor devices.

Porous worm-like NiMoO4 coaxially decorated electrospun carbon nanofiber as binder-free electrodes for high performance supercapacitors and lithium-ion batteries

NASA Astrophysics Data System (ADS)

Tian, Xiaodong; Li, Xiao; Yang, Tao; Wang, Kai; Wang, Hongbao; Song, Yan; Liu, Zhanjun; Guo, Quangui

2018-03-01

The peculiar architectures consisting of electrospun carbon nanofibers coaxially decorated by porous worm-like NiMoO4 were successfully fabricated for the first time to address the poor cycling stability and inferior rate capability of the state-of-the-art NiMoO4-based electrodes caused by the insufficient structural stability, dense structure and low conductivity. The porous worm-like structure endows the electrode high capacitance/capacity due to large effective specific surface area and short electron/ion diffusion channels. Moreover, the robust integrated electrode with sufficient internal spaces can self-accommodate volume variation during charge/discharge processes, which is beneficial to the structural stability and integrity. By the virtue of rational design of the architecture, the hybrid electrode delivered high specific capacitance (1088.5 F g-1 at 1 A g-1), good rate capability (860.3 F g-1 at 20 A g-1) and long lifespan with a capacitance retention of 73.9% after 5000 cycles when used as supercapacitor electrode. For lithium-ion battery application, the electrode exhibited a high reversible capacity of 1132.1 mAh g-1 at 0.5 A g-1. Notably, 689.7 mAh g-1 can be achieved even after 150 continuous cycles at a current density of 1 A g-1. In the view of their outstanding electrochemical performance and the cost-effective fabrication process, the integrated nanostructure shows great promising applications in energy storage.

Ni foam supported quasi-core-shell structure of ultrathin Ti3C2 nanosheets through electrostatic layer-by-layer self-assembly as high rate-performance electrodes of supercapacitors

NASA Astrophysics Data System (ADS)

Tian, Yapeng; Yang, Chenhui; Que, Wenxiu; He, Yucheng; Liu, Xiaobin; Luo, Yangyang; Yin, Xingtian; Kong, Ling Bing

2017-11-01

Supercapacitor, as an important energy storage device, is a critical component for next generation electric power system, due to its high power density and long cycle life. In this study, a novel electrode material with quasi-core-shell structure, consisting of negatively charged few layer Ti3C2 nanosheets (FL-Ti3C2) and positively charged polyethyleneimine as building blocks, has been prepared by using an electrostatic layer-by-layer self-assembly method, with highly conductive Ni foam to be used as the skeleton. The unique quasi-core-shell structured ultrathin Ti3C2 nanosheets provide an excellent electron channel, ion transport channel and large effective contact area, thus leading to a great improvement in electrochemical performance of the material. The specific capacitance of the binder-free FL-Ti3C2@Ni foam electrodes reaches 370 F g-1 at the scan rate of 2 mV s-1 and a specific capacitance of 117 F g-1 is obtained even at the scan rate of 1000 mV s-1 in the electrolyte of Li2SO4, indicating a high rate performance. In addition, this electrode shows a long-term cyclic stability with a loss of only 13.7% after 10,000 circles. Furthermore, quantitative analysis has been conducted to ensure the relationship between the capacitive contribution and the rate performance of the as-fabricated electrode.

Ni3Si2 nanowires grown in situ on Ni foam for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Jiang, Yizhe; Li, Zhihui; Li, Beibei; Zhang, Jinying; Niu, Chunming

2016-07-01

Ni3Si2 nanowires and nanoawls have grown in situ on the surface of Ni foams by a controlled low pressure chemical vapor deposition process. Structural characterization shows that the individual Ni3Si2 nanowire is single crystal covered with a thin layer (1-2 nm) of SiO2 with a diameter of ∼20-30 nm and length of ten's micrometers. Individual nanoawl with a circular cone shape is polycrystalline. Both Ni3Si2 nanowire and nanoawl samples are evaluated as potential electrode materials for supercapacitors. The nanowire electrode delivers a very high specific capacitance and excellent rate capability. A specific capacitance of 760 F g-1 is measured at current density of 0.5 A g-1, which decreases to 518 F g-1 when the current density increases to 10 A g-1. The capacitance is dominated by pseudocapacitance with a mechanism similar to that of NiO or Ni(OH)2 widely studied in the literature. An asymmetric supercapacitor fabricated by pairing Ni3Si2 nanowire electrode with an activated carbon electrode exhibits energy densities of 17.5 Wh kg-1 and 8.8 Wh kg-1 at power densites of 301 W kg-1 and 3000 W kg-1.

A novel SWCNT-polyoxometalate nanohybrid material as an electrode for electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Chen, Han-Yi; Al-Oweini, Rami; Friedl, Jochen; Lee, Ching Yi; Li, Linlin; Kortz, Ulrich; Stimming, Ulrich; Srinivasan, Madhavi

2015-04-01

A novel nanohybrid material that combines single-walled carbon nanotubes (SWCNTs) with a polyoxometalate (TBA)5[PVV2MoVI10O40] (TBA-PV2Mo10, TBA: [(CH3(CH2)3)4N]+, tetra-n-butyl ammonium) is investigated for the first time as an electrode material for supercapacitors (SCs) in this study. The SWCNT-TBA-PV2Mo10 material has been prepared by a simple solution method which electrostatically attaches anionic [PV2Mo10O40]5- anions with organic TBA cations on the SWCNTs. The electrochemical performance of SWCNT-TBA-PV2Mo10 electrodes is studied in an acidic aqueous electrolyte (1 M H2SO4) by galvanostatic charge/discharge and cyclic voltammetry. In this SWCNT-TBA-PV2Mo10 nanohybrid material, TBA-PV2Mo10 provides redox activity while benefiting from the high electrical conductivity and high double-layer capacitance of the SWCNTs that improve both energy and power density. An assembled SWCNT-TBA-PV2Mo10 symmetric SC exhibits a 39% higher specific capacitance as compared to a symmetric SC employing only SWCNTs as electrode materials. Furthermore, the SWCNT-TBA-PV2Mo10 SC exhibits excellent cycling stability, retaining 95% of its specific capacitance after 6500 cycles.

A novel SWCNT-polyoxometalate nanohybrid material as an electrode for electrochemical supercapacitors.

PubMed

Chen, Han-Yi; Al-Oweini, Rami; Friedl, Jochen; Lee, Ching Yi; Li, Linlin; Kortz, Ulrich; Stimming, Ulrich; Srinivasan, Madhavi

2015-05-07

A novel nanohybrid material that combines single-walled carbon nanotubes (SWCNTs) with a polyoxometalate (TBA)5[PVMoO40] (TBA-PV2Mo10, TBA: [(CH3(CH2)3)4N](+), tetra-n-butyl ammonium) is investigated for the first time as an electrode material for supercapacitors (SCs) in this study. The SWCNT-TBA-PV2Mo10 material has been prepared by a simple solution method which electrostatically attaches anionic [PV2Mo10O40](5-) anions with organic TBA cations on the SWCNTs. The electrochemical performance of SWCNT-TBA-PV2Mo10 electrodes is studied in an acidic aqueous electrolyte (1 M H2SO4) by galvanostatic charge/discharge and cyclic voltammetry. In this SWCNT-TBA-PV2Mo10 nanohybrid material, TBA-PV2Mo10 provides redox activity while benefiting from the high electrical conductivity and high double-layer capacitance of the SWCNTs that improve both energy and power density. An assembled SWCNT-TBA-PV2Mo10 symmetric SC exhibits a 39% higher specific capacitance as compared to a symmetric SC employing only SWCNTs as electrode materials. Furthermore, the SWCNT-TBA-PV2Mo10 SC exhibits excellent cycling stability, retaining 95% of its specific capacitance after 6500 cycles.

Characterization and organic electric-double-layer-capacitor application of KOH activated coal-tar-pitch-based carbons: Effect of carbonization temperature

NASA Astrophysics Data System (ADS)

Choi, Poo Reum; Lee, Eunji; Kwon, Soon Hyung; Jung, Ji Chul; Kim, Myung-Soo

2015-12-01

The present study reports the influence of pre-carbonization on the properties of KOH-activated coal tar pitch (CTP). The change of crystallinity and pore structure of pre-carbonized CTPs as well as their activated carbons (ACs) as function of pre-carbonization temperature are investigated. The crystallinity of pre-carbonized CTPs increases with increasing the carbonization temperature up to 600 °C, but a disorder occurs during the carbonization around 700 °C and an order happens gradually with increasing the carbonization temperatures in range of 800-1000 °C. The CTPs pre-carbonized at high temperatures are more difficult to be activated with KOH than those pre-carbonized at low temperatures due to the increase of micro-crystalline size and the decrease of surface functional groups. The micro-pores and meso-pores are well developed at around 1.0 nm and 2.4 nm, respectively, as the ACs are pre-carbonized at temperatures of 500-600 °C, exhibiting high specific capacitances as electrode materials for electric double layer capacitor (EDLC). Although the specific surface area (SSA) and pore volume of ACs pre-carbonized at temperatures of 900-1000 °C are extraordinary low (non-porous) as compared to those of AC pre-carbonized at 600 °C, their specific capacitances are comparable to each other. The large specific capacitances with low SSA ACs can be attributed to the structural change resulting from the electrochemical activation during the 1st charge above 2.0 V.

High performance asymmetric supercapacitor based on molybdenum disulphide/graphene foam and activated carbon from expanded graphite.

PubMed

Masikhwa, Tshifhiwa M; Madito, Moshawe J; Bello, Abdulhakeem; Dangbegnon, Julien K; Manyala, Ncholu

2017-02-15

Molybdenum disulphide which has a graphene-like single layer structure has excellent mechanical and electrical properties and unique morphology, which might be used with graphene foam as composite in supercapacitor applications. In this work, Molybdenum disulphide (MoS 2 )/graphene foam (GF) composites with different graphene foam loading were synthesized by the hydrothermal process to improve on specific capacitance of the composites. Asymmetric supercapacitor device was fabricated using the best performing MoS 2 /GF composite and activated carbon derived from expanded graphite (AEG) as positive and negative electrodes, respectively, in 6M KOH electrolyte. The asymmetric MoS 2 /GF//AEG device exhibited a maximum specific capacitance of 59Fg -1 at a current density of 1Ag -1 with maximum energy and power densities of 16Whkg -1 and 758Wkg -1 , respectively. The supercapacitor also exhibited a good cyclic stability with 95% capacitance retention over 2000 constant charge-discharge cycles. The results obtained demonstrate the potential of MoS 2 /GF//AEG as a promising material for electrochemical energy storage application. Copyright © 2016 Elsevier Inc. All rights reserved.

Novel ultrathin Bi2O3 nanowires for supercapacitor electrode materials with high performance

NASA Astrophysics Data System (ADS)

Qiu, Yongfu; Fan, Hongbo; Chang, Xueyi; Dang, Haifeng; Luo, Qun; Cheng, Zhiyu

2018-03-01

In this paper, the ultrathin Bi2O3 nanowires are synthesized by an oxidative metal vapor transport deposition technique. Their diameters and length are about 10 nm and several tens of micrometers, the growth direction is along [101] and the specific surface area is about 7.34 m2 g-1. The galvanostatic charge-discharge measurement results show that the specific capacitances of the Bi2O3 nanowires-based electrodes increase with the decrease of the current densities. The maximum capacitance is 691.3 F g-1 at the current density of 2.0 A g-1. The Ragone plot shows that the Bi2O3 nanowires has excellent supercapacitive performance. Moreover, the cyclic stability is measured by the galvanostatic charge/discharge technique at a constant current density of 10.0 A g-1 in 6.0 M KOH electrolyte. The results show the excellent capacitance retention of 75.5% over 3000 cycles. In a word, the Bi2O3 nanowires should be the ideal potential electrode materials for low-costing and effective electrochemical supercapacitors.

Robust and conductive two-dimensional metal-organic frameworks with exceptionally high volumetric and areal capacitance

DOE PAGES

Feng, Dawei; Lei, Ting; Lukatskaya, Maria R.; ...

2018-01-01

For miniaturized capacitive energy storage, volumetric and areal capacitances are more important metrics than gravimetric ones because of the constraints imposed by device volume and chip area. Typically used in commercial supercapacitors, porous carbons, although they provide a stable and reliable performance, lack volumetric performance because of their inherently low density and moderate capacitances. In this paper, we report a high-performing electrode based on conductive hexaaminobenzene (HAB)-derived two-dimensional metal-organic frameworks (MOFs). In addition to possessing a high packing density and hierarchical porous structure, these MOFs also exhibit excellent chemical stability in both acidic and basic aqueous solutions, which is inmore » sharp contrast to conventional MOFs. Submillimetre-thick pellets of HAB MOFs showed high volumetric capacitances up to 760 F cm -3 and high areal capacitances over 20 F cm -2. Furthermore, the HAB MOF electrodes exhibited highly reversible redox behaviours and good cycling stability with a capacitance retention of 90% after 12,000 cycles. In conclusion, these promising results demonstrate the potential of using redox-active conductive MOFs in energy-storage applications.« less

Robust and conductive two-dimensional metal-organic frameworks with exceptionally high volumetric and areal capacitance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Dawei; Lei, Ting; Lukatskaya, Maria R.

For miniaturized capacitive energy storage, volumetric and areal capacitances are more important metrics than gravimetric ones because of the constraints imposed by device volume and chip area. Typically used in commercial supercapacitors, porous carbons, although they provide a stable and reliable performance, lack volumetric performance because of their inherently low density and moderate capacitances. In this paper, we report a high-performing electrode based on conductive hexaaminobenzene (HAB)-derived two-dimensional metal-organic frameworks (MOFs). In addition to possessing a high packing density and hierarchical porous structure, these MOFs also exhibit excellent chemical stability in both acidic and basic aqueous solutions, which is inmore » sharp contrast to conventional MOFs. Submillimetre-thick pellets of HAB MOFs showed high volumetric capacitances up to 760 F cm -3 and high areal capacitances over 20 F cm -2. Furthermore, the HAB MOF electrodes exhibited highly reversible redox behaviours and good cycling stability with a capacitance retention of 90% after 12,000 cycles. In conclusion, these promising results demonstrate the potential of using redox-active conductive MOFs in energy-storage applications.« less

Robust and conductive two-dimensional metal-organic frameworks with exceptionally high volumetric and areal capacitance

NASA Astrophysics Data System (ADS)

Feng, Dawei; Lei, Ting; Lukatskaya, Maria R.; Park, Jihye; Huang, Zhehao; Lee, Minah; Shaw, Leo; Chen, Shucheng; Yakovenko, Andrey A.; Kulkarni, Ambarish; Xiao, Jianping; Fredrickson, Kurt; Tok, Jeffrey B.; Zou, Xiaodong; Cui, Yi; Bao, Zhenan

2018-01-01

For miniaturized capacitive energy storage, volumetric and areal capacitances are more important metrics than gravimetric ones because of the constraints imposed by device volume and chip area. Typically used in commercial supercapacitors, porous carbons, although they provide a stable and reliable performance, lack volumetric performance because of their inherently low density and moderate capacitances. Here we report a high-performing electrode based on conductive hexaaminobenzene (HAB)-derived two-dimensional metal-organic frameworks (MOFs). In addition to possessing a high packing density and hierarchical porous structure, these MOFs also exhibit excellent chemical stability in both acidic and basic aqueous solutions, which is in sharp contrast to conventional MOFs. Submillimetre-thick pellets of HAB MOFs showed high volumetric capacitances up to 760 F cm-3 and high areal capacitances over 20 F cm-2. Furthermore, the HAB MOF electrodes exhibited highly reversible redox behaviours and good cycling stability with a capacitance retention of 90% after 12,000 cycles. These promising results demonstrate the potential of using redox-active conductive MOFs in energy-storage applications.

The effects of amine/nitro/hydroxyl groups on the benzene rings of redox additives on the electrochemical performance of carbon-based supercapacitors.

PubMed

Huang, Xuan; Wang, Qian; Chen, Xiang Ying; Zhang, Zhong Jie

2016-04-21

In this work, a series of porous carbon materials with hierarchical porosities have been synthesized via a template carbonization method, in which cheap CaCO3 serves as a template and glucose as a carbon precursor. During the carbonization process, CO2 produced by the decomposition of the CaCO3 template can act as an internal activating agent, significantly improving microporosity and mesoporosity. All the carbon materials obtained by regulating the ratio of glucose to CaCO3 exhibit the amorphous features with a low graphitization degree. Among them, the carbon-1 : 2 sample shows a high BET surface area of up to 818.5 m(2) g(-1) and a large total pore volume of 1.78 cm(3) g(-1) as well as a specific capacitance of 107.0 F g(-1) at 1 A g(-1). In addition, a series of hydroquinone (HQ), p-aminophenol (PAP) and p-nitrophenol (PNP) as novel redox additives that can produce pseudo-capacitances have been added into the KOH electrolyte for promoting the total capacitive performances via redox reactions at the electrode-electrolyte interface. As expected, a 2.5-fold increase in the galvanostatic capacitance of 240.0 F g(-1) in the HQ-0.5 electrolyte occurs, compared with the conventional KOH electrolyte. Similarly, the PAP-0.5 electrolyte and the PNP-0.5 electrolyte also show a high specific capacitance of 184.0 F g(-1) at 2 A g(-1) (156.6 F g(-1) at 3 A g(-1)) and 153.0 F g(-1) at 3 A g(-1), respectively. Additionally, the three kinds of electrolytes exhibit excellent cyclic stability. The remarkable improvement of supercapacitors is attributed to the quick reversible Faradaic reactions of amine and hydroxyl groups adhering to the phenyl rings, which largely accelerates electron migration and brings additional pseudocapacitive contribution for carbon-based supercapacitors.

Preparation of graphene nanosheet/carbon nanotube/polyaniline composite as electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Yan, Jun; Wei, Tong; Fan, Zhuangjun; Qian, Weizhong; Zhang, Milin; Shen, Xiande; Wei, Fei

Graphene nanosheet/carbon nanotube/polyaniline (GNS/CNT/PANI) composite is synthesized via in situ polymerization. GNS/CNT/PANI composite exhibits the specific capacitance of 1035 F g -1 (1 mV s -1) in 6 M of KOH, which is a little lower than GNS/PANI composite (1046 F g -1), but much higher than pure PANI (115 F g -1) and CNT/PANI composite (780 F g -1). Though a small amount of CNTs (1 wt.%) is added into GNS, the cycle stability of GNS/CNT/PANI composite is greatly improved due to the maintenance of highly conductive path as well as mechanical strength of the electrode during doping/dedoping processes. After 1000 cycles, the capacitance decreases only 6% of initial capacitance compared to 52% and 67% for GNS/PANI and CNT/PANI composites.

On the correlation between the porous structure and the electrochemical response of powdered and monolithic carbon aerogels as electrodes for capacitive deionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Macías, C., E-mail: carlosmacias@nanoquimia.com; Lavela, P.; Rasines, G.

2016-10-15

The combined effect of resorcinol/catalyst (100≤R/C≤800) and resorcinol/water (0.04≤R/W≤0.13) molar ratio on the textural and capacitive properties of carbon aerogels with potential application for capacitive deionization has been evaluated. Activated and pyrolyzed aerogels were synthesized by the sol-gel polymerization of resorcinol-formaldehyde mixtures and dried in supercritical conditions. Data show that high R/C and R/W molar ratios lead to materials with large pores in the mesopore range, whereas the surface area and micropore volumes remain somewhat the same. The activation of the aerogels increased the differences in the specific surface and micropore volumes due to the development of microporosity. This effectmore » was more remarkable for the samples with low R/C whatever the R/W ratio, indicating that the carbon aerogel obtained using high amounts of catalyst are more prone to be activated. Regarding the electrochemical features of the aerogels, low capacitance values were measured in aerogels combining low R/W and high R/C and reciprocally low R/C and high R/W molar ratios, due to their higher resistance. Polarization resistances were found to be slightly higher for the pyrolyzed than for activated aerogels, and followed a decreasing trend with the mesoporosity, indicating the outstanding contribution of the mesoporous network to provide a good kinetic response. The desalting capacity of monolithic aerogels showed a simultaneous dependence with the surface area and the resistivity of the electrodes, pointing out the importance of performing electrochemical measurements in adequate cell configurations (i.e., desalting units) upon the intended application. - Graphical abstract: The textural properties of carbon aerogels are strongly influenced by the synthesis parameters precursor to catalyst (R/C) and water (R/C) ratios. The volumetric capacitance measured in a symmetric cell with monolithic electrodes of carbon aerogel strongly correlates with both surface area and electrical resistivity. - Highlights: • Influence of the synthesis conditions on the properties of carbon aerogels is reported. • Specific surface decreases in the activated samples when either R/C or R/W increase. • An enhanced decrease of the capacitance was observed when R/C and R/W increase. • Ohmic resistance of the electrodes that strongly depends on the R/W and R/C. • Electrosorption capacity is successfully correlated to surface area and resistivity.« less

A Solid-State Fibriform Supercapacitor Boosted by Host-Guest Hybridization between the Carbon Nanotube Scaffold and MXene Nanosheets.

PubMed

Yu, Chenyang; Gong, Yujiao; Chen, Ruyi; Zhang, Mingyi; Zhou, Jinyuan; An, Jianing; Lv, Fan; Guo, Shaojun; Sun, Gengzhi

2018-06-25

Fiber-shaped supercapacitors with improved specific capacitance and high rate capability are a promising candidate as power supply for smart textiles. However, the synergistic interaction between conductive filaments and active nanomaterials remains a crucial challenge, especially when hydrothermal or electrochemical deposition is used to produce a core (fiber)-shell (active materials) fibrous structure. On the other hand, although 2D pseudocapacitive materials, e.g., Ti 3 C 2 T x (MXene), have demonstrated high volumetric capacitance, high electrical conductivity, and hydrophilic characteristics, MXene-based electrodes normally suffer from poor rate capability owing to the sheet restacking especially when the loading level is high and solid-state gel is used as electrolyte. Herein, by hosting MXene nanosheets (Ti 3 C 2 T x ) in the corridor of a scrolled carbon nanotube (CNT) scaffold, a MXene/CNT fiber with helical structure is successfully fabricated. These features offer open spaces for rapid ion diffusion and guarantee fast electron transport. The solid-state supercapacitor based on such hybrid fibers with gel electrolyte coating exhibits a volumetric capacitance of 22.7 F cm -3 at 0.1 A cm -3 with capacitance retention of 84% at current density of 1.0 A cm -3 (19.1 F cm -3 ), improved volumetric energy density of 2.55 mWh cm -3 at the power density of 45.9 mW cm -3 , and excellent mechanical robustness. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Whole-tree water transport scales with sapwood capacitance in tropical forest canopy trees.

Treesearch

F.C. Meinzer; S.A. James; G. Goldstein; D. Woodruff

2003-01-01

The present study examines the manner in which several whole-tree water transport properties scale with species specific variation in sapwood water storage capacity. The hypothesis that constraints on relationships between sapwood capacitance and other water relations characteristics lead to predictable scaling relationships between intrinsic capacitance and whole-tree...

Highly Uniform Anodically Deposited Film of MnO2 Nanoflakes on Carbon Fibers for Flexible and Wearable Fiber-Shaped Supercapacitors.

PubMed

Rafique, Amjid; Massa, Andrea; Fontana, Marco; Bianco, Stefano; Chiodoni, Angelica; Pirri, Candido F; Hernández, Simelys; Lamberti, Andrea

2017-08-30

A highly uniform porous film of MnO 2 was deposited on carbon fiber by anodic electrodeposition for the fabrication of high-performance electrodes in wearable supercapacitors (SCs) application. The effects of potentiostatic and galvanostatic electrodeposition and the deposition time were investigated. The morphology, crystalline structure, and chemical composition of the obtained fiber-shaped samples were analyzed by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The charge storage performance of the carbon fibers@MnO 2 composite electrode coupled to a gel-like polymeric electrolyte was investigated by cyclic voltammetry and galvanostatic charge-discharge measurements. The specific capacitance of the optimized carbon fiber@MnO 2 composite electrodes could reach up to 62 F g -1 corresponding to 23 mF cm -1 in PVA/NaCl gel-polymer electrolyte, i.e., the highest capacitance value ever reported for fiber-shaped SCs. Finally, the stability and the flexibility of the device were studied, and the results indicate exceptional capacitance retention and superior stability of the device subjected to bending even at high angles up to 150°.

Polyaniline nanofiber sponge filled graphene foam as high gravimetric and volumetric capacitance electrode

NASA Astrophysics Data System (ADS)

Pedrós, J.; Boscá, A.; Martínez, J.; Ruiz-Gómez, S.; Pérez, L.; Barranco, V.; Calle, F.

2016-06-01

A 3D hierarchical porous composite structure is developed via the controlled electrodeposition of a polyaniline nanofiber sponge (PANI-NFS) that fills the pores of a chemical vapor deposited graphene foam (GF). The PANI-NFS/GF composite combines the efficient electronic transport in the GF scaffold (with 100-500 μm pore size) with the rapid diffusion of the electrolyte ions into the high-specific-surface-area and densely-packed PANI-NFS (with 100-500 nm pore size). The factor of 1000 in the pore hierarchy and the synergy between the materials, that form a supercapacitor composite electrode with an integrated extended current collector, lead to both very high gravimetric and volumetric capacitances. In particular, values of 1474 F g-1 and 86 F cm-3 for a GF filling factor of 11% (leading to an estimated value of 782 F cm-3 for 100%), respectively, are obtained at a current density of 0.47 A g-1. Moreover, the composite electrode presents a capacitance retention of 83% after 15000 cycles. This excellent behavior makes the PANI-NFS/GF composite electrodes very attractive for high-performance supercapacitors.

Facile fabrication of self-assembled polyaniline nanotubes doped with D-tartaric acid for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Mu, Jingjing; Ma, Guofu; Peng, Hui; Li, Jiajia; Sun, Kanjun; Lei, Ziqiang

2013-11-01

Polyaniline (PANI) nanotubes with outstanding electrochemical properties have been successfully synthesized via a simple chemical template-free method in the presence of D-tartaric acid (D-TA) as the dopant, and ammonium persulfate ((NH4)2S2O8) as the oxidant. The morphologies and structures of PANI-(D-TA) with different [D-TA]/[aniline] molar ratios are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) and X-ray diffraction (XRD). To assess the electrochemical properties of PANI-(D-TA) materials, cyclic voltammetry (CV) and galvanostatic charging-discharging measurements are performed. The PANI-(D-TA) nanotubes electrode, with [D-TA]/[aniline] molar ratio of 1:1, exhibits larger specific capacitance (as high as 625 F g-1 at 1 A g-1) and higher capacitance retention (77% of its initial capacitance after 500 cycles) in 1 M H2SO4 aqueous solution. The remarkable electrochemical characteristics of PANI-(D-TA) are mainly attributed to their unique nanotubular structures, which provide a high electrode/electrolyte contact area and short ions diffusion path. These novel PANI-(D-TA) nanotubes will be promising electrode materials for high-performance supercapacitors.

Aspheric surface measurement using capacitive probes

NASA Astrophysics Data System (ADS)

Tao, Xin; Yuan, Daocheng; Li, Shaobo

2017-02-01

With the application of aspheres in optical fields, high precision and high efficiency aspheric surface metrology becomes a hot research topic. We describe a novel method of non-contact measurement of aspheric surface with capacitive probe. Taking an eccentric spherical surface as the object of study, the averaging effect of capacitive probe measurement and the influence of tilting the capacitive probe on the measurement results are investigated. By comparing measurement results from simultaneous measurement of the capacitive probe and contact probe of roundness instrument, this paper indicates the feasibility of using capacitive probes to test aspheric surface and proposes the compensation method of measurement error caused by averaging effect and the tilting of the capacitive probe.

Electropolymerization of high stable poly(3,4-ethylenedioxythiophene) in ionic liquids and its potential applications in electrochemical capacitor

NASA Astrophysics Data System (ADS)

Liu, Keke; Hu, Zhenglong; Xue, Rong; Zhang, Jianrong; Zhu, Junjie

2008-05-01

Poly(3,4-ethylenedioxythiophene) (PEDOT) has been successfully electropolymerized using a purified 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) as both the growth medium and the supporting electrolyte. The electrochemical performance of the PEDOT thin film was investigated in 1 mol L-1 H2SO4 solution. It possesses nearly ideal capacitive property, and its specific capacitance is about 130 F g-1. Compared with other conducting polymers, enhanced cycling lifetime (up to 70,000 cycles), which is close to that of active carbon materials, was observed on repetitive redox cycling.

Electrochemical performance of carbon-coated lithium manganese silicate for asymmetric hybrid supercapacitors

NASA Astrophysics Data System (ADS)

Karthikeyan, K.; Aravindan, V.; Lee, S. B.; Jang, I. C.; Lim, H. H.; Park, G. J.; Yoshio, M.; Lee, Y. S.

Nanoscale carbon-coated Li 2MnSiO 4 powder is prepared using a conventional solid-state method and can be used as the negative electrode in a Li 2MnSiO 4/activated carbon (AC) hybrid supercapacitor. Carbon-coated Li 2MnSiO 4 material presents a well-developed orthorhombic crystal structure with a P mn2 1 space group, although there is a small impurity of MnO. The maximum specific capacitance of the Li 2MnSiO 4/AC hybrid supercapacitor is 43.2 F g -1 at 1 mA cm -2 current density. The cell delivers a specific energy as high as 54 Wh kg -1 at a specific power of 150 W kg -1 and also exhibits an excellent cycle performance with more than 99% columbic efficiency and the maintenance of 85% of its initial capacitance after 1000 cycles.

Measurement of Gas-Liquid Two-Phase Flow in Micro-Pipes by a Capacitance Sensor

PubMed Central

Ji, Haifeng; Li, Huajun; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

2014-01-01

A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used to measure the small capacitance signals based on the differential sampling method. The performance and feasibility of the capacitance method are investigated and discussed. The capacitance signal is analyzed, which can reflect the voidage variation of two-phase flow. The gas slug velocity is determined through a cross-correlation technique using two identical capacitance sensors. The simulation and experimental results show that the presented capacitance measurement system is successful. Research work also verifies that the capacitance sensor is an effective method for the measurement of gas liquid two-phase flow parameters in micro-pipes. PMID:25587879

Measurement of gas-liquid two-phase flow in micro-pipes by a capacitance sensor.

PubMed

Ji, Haifeng; Li, Huajun; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

2014-11-26

A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used to measure the small capacitance signals based on the differential sampling method. The performance and feasibility of the capacitance method are investigated and discussed. The capacitance signal is analyzed, which can reflect the voidage variation of two-phase flow. The gas slug velocity is determined through a cross-correlation technique using two identical capacitance sensors. The simulation and experimental results show that the presented capacitance measurement system is successful. Research work also verifies that the capacitance sensor is an effective method for the measurement of gas liquid two-phase flow parameters in micro-pipes.

Synthesis of ultrathin mesoporous NiCo2O4 nanosheets on carbon fiber paper as integrated high-performance electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Deng, Fangze; Yu, Lin; Cheng, Gao; Lin, Ting; Sun, Ming; Ye, Fei; Li, Yongfeng

2014-04-01

Two-dimensional ultrathin mesoporous NiCo2O4 nanosheets on carbon fiber paper (CFP) are synthesized through a facile solvothermal method combined with a post thermal treatment. The well interconnected ultrathin NiCo2O4 nanosheets directly grown on the carbon nanofibers could allow for easy diffusion of the electrolyte, shorten the transport path of ion and electron and accommodate the strain during cycling. As a result, superior pseudocapacitive performance is achieved with large specific capacitance of 999 F g-1 at a high current density of 20 A g-1. The capacitance loss is 15.6% after 3000 cycles at a current density of 10 A g-1, displaying good cycle ability and high rate capability.

3D hybrid-porous carbon derived from carbonization of metal organic frameworks for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Bao, Weizhai; Mondal, Anjon Kumar; Xu, Jing; Wang, Chengyin; Su, Dawei; Wang, Guoxiu

2016-09-01

We report a rational design and synthesis of 3D hybrid-porous carbon with a hierarchical pore architecture for high performance supercapacitors. It contains micropores (<2 nm diameter) and mesopores (2-4 nm), derived from carbonization of unique porous metal organic frameworks (MOFs). Owning to the synergistic effect of micropores and mesopores, the hybrid-porous carbon has exceptionally high ion-accessible surface area and low ion diffusion resistance, which is desired for supercapacitor applications. When applied as electrode materials in supercapacitors, 3D hybrid-porous carbon demonstrates a specific capacitance of 332 F g-1 at a constant charge/discharge current of 500 mA g-1. The supercapacitors can endure more than 10,000 cycles without degradation of capacitance.

Ethanedithiol-treated manganese oxide nanoparticles for rapidly responsive and transparent supercapacitors

NASA Astrophysics Data System (ADS)

Ryu, Ilhwan; Kim, Green; Park, Dasom; Yim, Sanggyu

2015-11-01

Metal oxide nanoparticles (NPs) provide a large surface area and short diffusion pathways for ions in supercapacitor electrode materials. However, binders and conductive additives used for tight connections with current collectors and improved conductivity hamper these benefits. In this work, we successfully fix manganese oxide (Mn3O4) NPs onto ITO current collectors by a simple 1,2-ethanedithiol (EDT) treatment without using any binders or conductive additives. As compared to the electrode fabricated using binder-mixed Mn3O4 NPs, the EDT-treated electrode shows significantly improved specific capacitance of 403 F g-1 at a scan rate of 10 mV s-1. The EDT-treatment is more effective at higher scan rates. The specific capacitances, 278 F g-1 at 100 mV s-1 and 202 F g-1 at 200 mV s-1, are larger than those reported so far at scan rates ≥100 mV s-1. The deconvolution of capacitive elements indicates that these improved capacitive properties are attributed to large insertion elements of the binder-free NP electrodes. Furthermore, this additive-free electrode is highly transparent and can be easily fabricated by simple spray-coating on various substrates including polymer films, implying that this new method is promising for the fabrication of large-area, transparent and flexible electrodes for next-generation supercapacitors.

Engineering micro-supercapacitors of graphene nanowalls/Ni heterostructure based on microfabrication technology

NASA Astrophysics Data System (ADS)

Li, Jinhua; Zhu, Minjie; Wang, Zhuqing; Ono, Takahito

2016-10-01

Heterostructure of graphene nanowalls (GNW) supported Ni thin-layer was fabricated to form an on-chip pseudocapacitor via a standard microelectromechanical system process. Beyond a high-rate capability of the micro-supercapacitors, a large specific energy density of 2.1 mW h cm-3 and power density up to 5.91 W cm-3 have been achieved, which are two orders of magnitude higher than those commercial electrolytic capacitors and thin-film batteries, respectively. Rational analysis revealed a rapid GNW growth originated from the Pt current collector embedment by catalyzing hydrocarbon dissociating. The unique concept in our design includes that Ni was evaporated onto GNW to serve as both the shadow mask for microelectrode patterning and subsequently a precursor to be in-situ electrochemically converted into pseudo-capacitive Ni(OH)2 for capacitance enhancing. Addressing the challenge to uniformly coat in complex nanoporous structures, this strategy renders a conformal deposition of pseudo-capacitive material on individual graphene nanoflakes, leading to efficient merits harnessing of huge accessible surfaces from the conductive GNW networks and great capacitance of the Ni-based active materials for high performance delivery. The proof of concept can be potentially extended to other transition metals and paves the way to further apply GNW hybrids in diverse microsystems.

One-step hydrothermal synthesis of three-dimensional porous Ni-Co sulfide/reduced graphene oxide composite with optimal incorporation of carbon nanotubes for high performance supercapacitors.

PubMed

Chiu, Cheng-Ting; Chen, Dong-Hwang

2018-04-27

Three-dimensional (3D) porous Ni-Co sulfide/reduced graphene oxide composite with the appropriate incorporation of carbon nanotubes (NCS/rGO/CNT) was fabricated as a promising material for supercapacitor electrodes. It combined the high pseudo-capacitance of Ni-Co sulfide as well as the large specific surface area and electrical double layer capacitance of reduced graphene oxide (rGO). Carbon nanotubes (CNTs) were incorporated to act as the spacer for hindering the restacking of rGO and to construct a conductive network for enhancing the electron transport. The 3D porous NCS/rGO/CNT composite was fabricated by a facile one-step hydrothermal process in which Ni-Co sulfide nanosheets were synthesized and graphene oxide was reduced simultaneously. It was shown that the capacitance and cyclic performance indeed could be effectively improved via the appropriate addition of CNTs. In addition, a flexible all-solid-state asymmetric supercapacitor based on the NCS/rGO/CNT electrode was fabricated and exhibited the same capacitive electrochemical performance under bending. Also, it could successfully turn on a light-emitting diode light, revealing its feasibility in practical application. All results demonstrated that the developed NCS/rGO/CNT composite has potential application in supercapacitors.

One-step hydrothermal synthesis of three-dimensional porous Ni-Co sulfide/reduced graphene oxide composite with optimal incorporation of carbon nanotubes for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Chiu, Cheng-Ting; Chen, Dong-Hwang

2018-04-01

Three-dimensional (3D) porous Ni-Co sulfide/reduced graphene oxide composite with the appropriate incorporation of carbon nanotubes (NCS/rGO/CNT) was fabricated as a promising material for supercapacitor electrodes. It combined the high pseudo-capacitance of Ni-Co sulfide as well as the large specific surface area and electrical double layer capacitance of reduced graphene oxide (rGO). Carbon nanotubes (CNTs) were incorporated to act as the spacer for hindering the restacking of rGO and to construct a conductive network for enhancing the electron transport. The 3D porous NCS/rGO/CNT composite was fabricated by a facile one-step hydrothermal process in which Ni-Co sulfide nanosheets were synthesized and graphene oxide was reduced simultaneously. It was shown that the capacitance and cyclic performance indeed could be effectively improved via the appropriate addition of CNTs. In addition, a flexible all-solid-state asymmetric supercapacitor based on the NCS/rGO/CNT electrode was fabricated and exhibited the same capacitive electrochemical performance under bending. Also, it could successfully turn on a light-emitting diode light, revealing its feasibility in practical application. All results demonstrated that the developed NCS/rGO/CNT composite has potential application in supercapacitors.

All-nanotube stretchable supercapacitor with low equivalent series resistance.

PubMed

Gilshteyn, Evgenia P; Amanbayev, Daler; Anisimov, Anton S; Kallio, Tanja; Nasibulin, Albert G

2017-12-12

We report high-performance, stable, low equivalent series resistance all-nanotube stretchable supercapacitor based on single-walled carbon nanotube film electrodes and a boron nitride nanotube separator. A layer of boron nitride nanotubes, fabricated by airbrushing from isopropanol dispersion, allows avoiding problem of high internal resistance and short-circuiting of supercapacitors. The device, fabricated in a two-electrode test cell configuration, demonstrates electrochemical double layer capacitance mechanism and retains 96% of its initial capacitance after 20 000 electrochemical charging/discharging cycles with the specific capacitance value of 82 F g -1 and low equivalent series resistance of 4.6 Ω. The stretchable supercapacitor prototype withstands at least 1000 cycles of 50% strain with a slight increase in the volumetric capacitance from 0.4 to 0.5 mF cm -3 and volumetric power density from 32 mW cm -3 to 40 mW cm -3 after stretching, which is higher than reported before. Moreover, a low resistance of 250 Ω for the as-fabricated stretchable prototype was obtained, which slightly decreased with the strain applied up to 200 Ω. Simple fabrication process of such devices can be easily extended making the all-nanotube stretchable supercapacitors, presented here, promising elements in future wearable devices.

Design and fabrication of highly open nickel cobalt sulfide nanosheets on Ni foam for asymmetric supercapacitors with high energy density and long cycle-life

NASA Astrophysics Data System (ADS)

Zha, Daosong; Fu, Yongsheng; Zhang, Lili; Zhu, Junwu; Wang, Xin

2018-02-01

Nickel cobalt sulfides (NiCo-S) are promising electrode materials for high-performance supercapacitors but normally show poor rate capability and unsatisfactory long-term endurance. To overcome these disadvantages, a properly constructed electrode architecture with abundant electron transport channels, excellent electronic conductivity and robust structural stability is required. Herein, considering that in situ transformation can mostly retain the specific structural advantages of the precursors, a two-step strategy is purposefully developed to construct a binder-free electrode composed of interconnected NiCo-S nanosheets on Ni foam (NiCo-S/NF), in which NiCo-S/NF is synthesized via the in situ sulfuration of networked acetate anion-intercalated nickel cobalt layered double hydroxide nanosheets loaded on Ni foam (A-NiCo-LDH/NF). Noticeably, the optimized Ni1Co1-S/NF exhibits an ultrahigh specific capacitance of 2553.9 F g-1 at 0.5 A g-1, excellent rate capability (1898.1 F g-1 at 50 A g-1) and superior cycling stability (nearly 90% capacitance retention after 10,000 cycles). Furthermore, the assembled asymmetric supercapacitor based on Ni1Co1-S/NF demonstrates a high energy density of 58.1 Wh kg-1 at a power density of 796 W kg-1 and impressive long-term durability even after a repeated charge/discharge process as long as 70,000 cycles (∼92% capacitance retention). The attractive properties endow the Ni1Co1-S/NF electrode with significant potential for high-performance energy storage devices.

Construction of high-capacitance 3D CoO@polypyrrole nanowire array electrode for aqueous asymmetric supercapacitor.

PubMed

Zhou, Cheng; Zhang, Yangwei; Li, Yuanyuan; Liu, Jinping

2013-05-08

We have developed a supercapacitor electrode composed of well-aligned CoO nanowire array grown on 3D nickel foam with polypyrrole (PPy) uniformly immobilized onto or firmly anchored to each nanowire surface to boost the pseudocapacitive performance. The electrode architecture takes advantage of the high electrochemical activity from both the CoO and PPy, the high electronic conductivity of PPy, and the short ion diffusion pathway in ordered mesoporous nanowires. These merits together with the elegant synergy between CoO and PPy lead to a high specific capacitance of 2223 F g(-1) approaching the theoretical value, good rate capability, and cycling stability (99.8% capacitance retention after 2000 cycles). An aqueous asymmetric supercapacitor device with a maximum voltage of 1.8 V fabricated by using our hybrid array as the positive electrode and activated carbon film as the negative electrode has demonstrated high energy density (~43.5 Wh kg(-1)), high power density (~5500 W kg(-1) at 11.8 Wh kg(-1)) and outstanding cycleability (~20,000 times). After charging for only ~10 s, two such 4 cm(2) asymmetric supercapacitors connected in series can efficiently power 5 mm diameter red, yellow, and green round LED indicators (lasting for 1 h for red LED) and drive a mini 130 rotation-motor robustly.

High-performance flexible electrode based on electrodeposition of polypyrrole/MnO2 on carbon cloth for supercapacitors

NASA Astrophysics Data System (ADS)

Fan, Xingye; Wang, Xiaolei; Li, Ge; Yu, Aiping; Chen, Zhongwei

2016-09-01

A highly flexible electrodes based on electrodeposited MnO2 and polypyrrole composite on carbon cloth is designed and developed by a facile in-situ electrodeposition technique. Such flexible composite electrodes with multiply layered structure possess a high specific capacitance of 325 F g-1 at a current density of 0.2 A g-1, and an excellent rate capability with a capacitance retention of 70% at a high current density of 5.0 A g-1. The superior electrochemical performance is mainly due to the unique electrode with improved ion- and electron-transportation pathways as well as the efficient utilization of active materials and electrode robustness. The excellent electrochemical performance and the low cost property endow this flexible nanocomposite electrode with great promise in applications of flexible supercapacitors.

Facile synthesis of nickel-cobalt double hydroxide nanosheets with high rate capability for application in supercapacitor

NASA Astrophysics Data System (ADS)

Wang, Minmin; Xue, Junying; Zhang, Fangming; Ma, Wenle; Cui, Hongtao

2015-02-01

In this work, nickel-cobalt double hydroxide nanosheets with high rate capability are prepared by a facile epoxide precipitation route. The synthetic procedure includes an oxidization step using ammonium persulfate as oxidant and a precipitation step using propylene oxide as precipitation agent. As shown in the results of electrochemical characterization, high specific capacitance of 2548 F g-1 for this material can be obtained at current density of 0.9 A g-1 in aqueous solution of 3 mol L-1 KOH. It is surprising to notice that the capacitance of material still remains 1587 F g-1 at high current density of 35.7 A g-1. These results demonstrate that the as-prepared nickel-cobalt double hydroxide nanosheets are promising electrode material for supercapacitor application as a primary power source.

MnO2/carbon nanowalls composite electrode for supercapacitor application

NASA Astrophysics Data System (ADS)

Hassan, Sameh; Suzuki, Masaaki; Mori, Shinsuke; El-Moneim, Ahmed Abd

2014-03-01

Amorphous MnO2/carbon nanowalls composite films are developed for the supercapacitor applications. Synthesis of carbon nanowalls template is performed by plasma-enhanced chemical vapor deposition in a CO/H2 microwave discharge system. A well dispersion of amorphous MnO2 domains throughout carbon nanowalls template is obtained by potentiostatic anodic deposition technique. Carbon nanowalls enable to improve the capacitive behavior and rate capability of MnO2, a specific capacitance of 851 F g-1 at a current density of 1 mA cm-2 and charge transfer resistance of 1.02 Ω are obtained. MnO2/carbon nanowalls composite film exhibits energy density of 118 wh kg-1, power density of 783 wh kg-1, and capacitance retention of 92% after long cycle life of 2000 cycles by charging and discharging at 3 mA cm-2. The high density of atomic scale graphitic edges and large surface area of carbon nanowalls in conjunction with the presence of amorphous MnO2 domains facilitate rapid electron and ion transport and hence offering the potential of the improved capacitive behavior.

Facile Synthesis of Mixed Metal Organic Frameworks: Electrode Materials for Supercapacitor with Excellent Areal Capacitance and Operational Stability.

PubMed

Kazemi, Sayed Habib; Hosseinzadeh, Batoul; Kazemi, Hojjat; Kiani, Mohammad Ali; Hajati, Shaaker

2018-06-08

Electrode materials with high surface area, tailored pore size and efficient capability for ion insertion and enhanced transport of electrons and ions are needed for advanced supercapacitors. In the present study, a mixed metal organic framework (cobalt and manganese based MOF) was synthesized through a simple one pot solvothermal method and employed as the electrode material for supercapacitor. Notably, Co-Mn MOF electrode displayed a large surface area and excellent cycling stability (over 95% capacitance retention after 1500 cycles). Also, superior pseudocapacitive behavior was observed for Co-Mn MOF electrode in KOH electrolyte with an exceptional areal capacitance of 1.318 F cm-2. Moreover, an asymmetric supercapacitor was assembled using Co-Mn MOF and activated carbon electrode as positive and negative electrodes, respectively. The fabricated supercapacitor showed specific capacitances of 106.7 F g-1 at a scan rate of 10 mV s-1 and delivered maximum energy density of 30 Wh kg-1 at 2285.7 W kg-1. Our studies suggest the Co-Mn MOF as promising electrode materials for supercapacitor applications.

Fast fabrication of NiO@graphene composites for supercapacitor electrodes: Combination of reduction and deposition.

PubMed

Hui, Xu; Qian, Luming; Harris, Gary; Wang, Tongxin; Che, Jianfei

2016-11-05

Graphene-based inorganic composites have been attracting more and more attention since the attachment of inorganic nanoparticles instead of conducting polymeric materials to graphene sheets turns out higher capacitances and good capacity retention. Here we report a fast fabrication method to prepare NiO@graphene composite modified electrodes for supercapacitors. By this method, preparation of electrochemical active materials of NiO/graphene and modification of the electrode can be simultaneously performed, which is achieved separately by traditional method. Moreover, the problem of poor adhesion of active materials on the surface of the electrode can be well solved. The NiO particles introduced to the films exhibit pseudocapacitive behavior arising from the reversible Faradaic transitions of Ni(II)/Ni(III) and greatly improve the capacitance of the electrodes. With the increase in NiO content, highly reduced graphene can be obtained during cyclic voltammetry sweeping, leading to the increase in the electrode capacitance. The highest specific capacitance of the constructed electrodes can reach 1258 F/g at a current density of 5 A/g.

Capacitive behaviour of MnF2 and CoF2 submicro/nanoparticles synthesized via a mild ionic liquid-assisted route

NASA Astrophysics Data System (ADS)

Ma, Ruguang; Zhou, Yao; Yao, Lin; Liu, Guanghui; Zhou, Zhenzhen; Lee, Jong-Min; Wang, Jiacheng; Liu, Qian

2016-01-01

Submicro-/nano-sized MnF2 rods and hierarchical CoF2 cuboids are respectively synthesized via a facile precipitation method assisted by ionic liquid under a mild condition. The as-prepared MF2 (M = Mn, Co) submicro/nanoparticles exhibit impressive specific capacitance in 1.0 M KOH aqueous solution, especially at relatively high current densities, e.g. 91.2, 68.7 and 56.4 F g-1 for MnF2, and 81.7, 70.6 and 63.0 F g-1 for CoF2 at 5, 8 and 10 A g-1, respectively. The mechanism of striking capacitance of MF2 is clarified on the basis of analysing the cycled electrodes by different characterization techniques. Such remarkable capacitance is ascribed to the redox reactions between MF2 and MOOH in aqueous alkaline electrolytes, which can not be obtained in aqueous neutral electrolytes. This study for the first time provides direct evidences on the pseudocapacitance mechanism of MF2 in alkaline electrolytes and paves the way of application of transition metal fluorides as electrodes in supercapacitors.

Design and analysis of optimised class E power amplifier using shunt capacitance in the output structure

NASA Astrophysics Data System (ADS)

Hayati, Mohsen; Roshani, Sobhan; Zirak, Ali Reza

2017-05-01

In this paper, a class E power amplifier (PA) with operating frequency of 1 MHz is presented. MOSFET non-linear drain-to-source parasitic capacitance, linear external capacitance at drain-to-source port and linear shunt capacitance in the output structure are considered in design theory. One degree of freedom is added to the design of class E PA, by assuming the shunt capacitance in the output structure in the analysis. With this added design degree of freedom it is possible to achieve desired values for several parameters, such as output voltage, load resistance and operating frequency, while both zero voltage and zero derivative switching (ZVS and ZDS) conditions are satisfied. In the conventional class E PA, high value of peak switch voltage results in limitations for the design of amplifier, while in the presented structure desired specifications could be achieved with the safe margin of peak switch voltage. The results show that higher operating frequency and output voltage can also be achieved, compared to the conventional structure. PSpice software is used in order to simulate the designed circuit. The presented class E PA is designed, fabricated and measured. The measured results are in good agreement with simulation and theory results.

Large-scale synthesis of reduced graphene oxides with uniformly coated polyaniline for supercapacitor applications.

PubMed

Salunkhe, Rahul R; Hsu, Shao-Hui; Wu, Kevin C W; Yamauchi, Yusuke

2014-06-01

We report an effective route for the preparation of layered reduced graphene oxide (rGO) with uniformly coated polyaniline (PANI) layers. These nanocomposites are synthesized by chemical oxidative polymerization of aniline monomer in the presence of layered rGO. SEM, TEM, X-ray photoelectron spectroscopy (XPS), FTIR, and Raman spectroscopy analysis results demonstrated that reduced graphene oxide-polyaniline (rGO-PANI) nanocomposites are successfully synthesized. Because of synergistic effects, rGO-PANI nanocomposites prepared by this approach exhibit excellent capacitive performance with a high specific capacitance of 286 F g(-1) and high cycle reversibility of 94 % after 2000 cycles. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sulfurized activated carbon for high energy density supercapacitors

NASA Astrophysics Data System (ADS)

Huang, Yunxia; Candelaria, Stephanie L.; Li, Yanwei; Li, Zhimin; Tian, Jianjun; Zhang, Lili; Cao, Guozhong

2014-04-01

Sulfurized activated carbon (SAC), made by coating the pore surface with thiophenic sulfur functional groups from the pyrolysis of sulfur flakes, were characterized and tested for supercapacitor applications. From X-ray photoelectron spectroscopy (XPS), the sulfur content in the SAC was found to be 2.7 at%. Electrochemical properties from potentiostatic and galvanostatic measurements, and electrochemical impedance spectroscopy (EIS) were used to evaluate the effect of sulfur on porous carbon electrodes. The SAC electrode exhibits better conductivity, and an obvious increase in specific capacitance that is almost 40% higher than plain activated carbons (ACs) electrode at a high current density of 1.4 A g-1. The proposed mechanism for improved conductivity and capacitive performance due to the sulfur functional groups on ACs will be discussed.

High porous bio-nanocarbons prepared by carbonization and NaOH activation of polysaccharides for electrode material of EDLC

NASA Astrophysics Data System (ADS)

Takeuchi, Kenji; Fujishige, Masatsugu; Ishida, Nobuaki; Kunieda, Yoshihiro; Kato, Yosuke; Tanaka, Yusuke; Ochi, Toshiyuki; Shirotori, Hisashi; Uzuhashi, Yuji; Ito, Suguru; Oshida, Kyo-ichi; Endo, Morinobu

2018-07-01

Carbonization and post-activation of polysaccharides (utilized as food residue) created new bio-nanocarbons for the electrode of electric double layer capacitors (EDLC). Large specific capacitance (46.1 F/g, 26.4 F/cm3) and high rate performance was confirmed under optimized conditions of carbonization temperature (600 °C) and supplied amount of sodium hydroxide in NaOH-activation process (250 wt %). The capacitance and rate performance were larger than the reported values, 42.9 F/g, 19.7 F/cm3 of currently used activated carbon MSP-20. The feature that NaOH is usable as the activation agent, instead of KOH, is advantageous for reducing the cost of EDLC.

Trielectrode capacitive pressure transducer

NASA Technical Reports Server (NTRS)

Coon, G. W. (Inventor)

1976-01-01

A capacitive transducer and circuit especially suited for making measurements in a high-temperature environment are described. The transducer includes two capacitive electrodes and a shield electrode. As the temperature of the transducer rises, the resistance of the insulation between the capacitive electrode decreases and a resistive current attempts to interfere with the capacitive current between the capacitive electrodes. The shield electrode and the circuit coupled there reduce the resistive current in the transducer. A bridge-type circuit coupled to the transducer ignores the resistive current and measures only the capacitive current flowing between the capacitive electrodes.

Size-dependent capacitance of NiO nanoparticles synthesized with cathodic contact glow discharge electrolysis

NASA Astrophysics Data System (ADS)

Allagui, Anis; Alami, Abdul Hai; Baranova, Elena A.; Wüthrich, Rolf

2014-09-01

NiO nanoparticles of 70, 91 and 107 nm average diameter are synthesized by cathodic contact glow discharge electrolysis at 30, 36 and 42 VDC respectively, in 2 M H2SO4 + 0.5 M ethanol + 2.5 mg ml-1 of PVP, and are investigated for electrochemical energy storage. From the cyclic voltammetry and galvanostatic charge-discharge measurements in 1 M KOH, it was found that a maximum specific capacitance of 218 F g-1 is achieved with the 70 nm NiO nanoparticles at 2.7 A g-1. Larger nanoparticles of 91 and 107 nm diameter exhibit specific capacitances of 106 and 63 F g-1, respectively, suggesting a size-dependent capacitive performance enhanced with decreasing particles size.

Three-dimensional carbon nanotube networks with a supported nickel oxide nanonet for high-performance supercapacitors.

PubMed

Wu, Mao-Sung; Zheng, Yo-Ru; Lin, Guan-Wei

2014-08-04

A three-dimensional porous carbon nanotube film with a supported NiO nanonet was prepared by simple electrophoretic deposition and hydrothermal synthesis, which could deliver a high specific capacitance of 1511 F g(-1) at a high discharge current of 50 A g(-1) due to the significantly improved transport of the electrolyte and electrons.

Facile and environmentally friendly synthesis of ultrathin nickel hydroxide nanosheets with excellent supercapacitor performances

NASA Astrophysics Data System (ADS)

Hu, Xiaowei; Liu, Sheng; Li, Chenghui; Huang, Jiahao; Luv, Jixing; Xu, Pan; Liu, Jian; You, Xiao-Zeng

2016-06-01

In this article, we report a facile and environmentally friendly glutamic acid-assisted hydrothermal strategy for the preparation of ultrathin two-dimensional (2D) β-Ni(OH)2 nanosheets with a thickness of about 2 nm, which exhibit a maximum specific capacitance of 2537.4 F g-1 at a current density of 1 A g-1, even at 10 A g-1, the specific capacitance is still maintained at 2290.0 F g-1 with 77.6% retention after 3000 cycles.In this article, we report a facile and environmentally friendly glutamic acid-assisted hydrothermal strategy for the preparation of ultrathin two-dimensional (2D) β-Ni(OH)2 nanosheets with a thickness of about 2 nm, which exhibit a maximum specific capacitance of 2537.4 F g-1 at a current density of 1 A g-1, even at 10 A g-1, the specific capacitance is still maintained at 2290.0 F g-1 with 77.6% retention after 3000 cycles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02912d

High energy overcurrent protective device

DOEpatents

Praeg, Walter F.

1982-01-01

Electrical loads connected to capacitance elements in high voltage direct current systems are protected from damage by capacitance discharge overcurrents by connecting between the capacitance element and the load, a longitudinal inductor comprising a bifilar winding wound about a magnetic core, which forms an incomplete magnetic circuit. A diode is connected across a portion of the bifilar winding which conducts a unidirectional current only. Energy discharged from the capacitance element is stored in the inductor and then dissipated in an L-R circuit including the diode and the coil winding. Multiple high voltage circuits having capacitance elements may be connected to loads through bifilar windings all wound about the aforementioned magnetic core.

Scalable Synthesis of Triple-Core-Shell Nanostructures of TiO2 @MnO2 @C for High Performance Supercapacitors Using Structure-Guided Combustion Waves.

PubMed

Shin, Dongjoon; Shin, Jungho; Yeo, Taehan; Hwang, Hayoung; Park, Seonghyun; Choi, Wonjoon

2018-03-01

Core-shell nanostructures of metal oxides and carbon-based materials have emerged as outstanding electrode materials for supercapacitors and batteries. However, their synthesis requires complex procedures that incur high costs and long processing times. Herein, a new route is proposed for synthesizing triple-core-shell nanoparticles of TiO 2 @MnO 2 @C using structure-guided combustion waves (SGCWs), which originate from incomplete combustion inside chemical-fuel-wrapped nanostructures, and their application in supercapacitor electrodes. SGCWs transform TiO 2 to TiO 2 @C and TiO 2 @MnO 2 to TiO 2 @MnO 2 @C via the incompletely combusted carbonaceous fuels under an open-air atmosphere, in seconds. The synthesized carbon layers act as templates for MnO 2 shells in TiO 2 @C and organic shells of TiO 2 @MnO 2 @C. The TiO 2 @MnO 2 @C-based electrodes exhibit a greater specific capacitance (488 F g -1 at 5 mV s -1 ) and capacitance retention (97.4% after 10 000 cycles at 1.0 V s -1 ), while the absence of MnO 2 and carbon shells reveals a severe degradation in the specific capacitance and capacitance retention. Because the core-TiO 2 nanoparticles and carbon shell prevent the deformation of the inner and outer sides of the MnO 2 shell, the nanostructures of the TiO 2 @MnO 2 @C are preserved despite the long-term cycling, giving the superior performance. This SGCW-driven fabrication enables the scalable synthesis of multiple-core-shell structures applicable to diverse electrochemical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wrapping Aligned Carbon Nanotube Composite Sheets around Vanadium Nitride Nanowire Arrays for Asymmetric Coaxial Fiber-Shaped Supercapacitors with Ultrahigh Energy Density.

PubMed

Zhang, Qichong; Wang, Xiaona; Pan, Zhenghui; Sun, Juan; Zhao, Jingxin; Zhang, Jun; Zhang, Cuixia; Tang, Lei; Luo, Jie; Song, Bin; Zhang, Zengxing; Lu, Weibang; Li, Qingwen; Zhang, Yuegang; Yao, Yagang

2017-04-12

The emergence of fiber-shaped supercapacitors (FSSs) has led to a revolution in portable and wearable electronic devices. However, obtaining high energy density FSSs for practical applications is still a key challenge. This article exhibits a facile and effective approach to directly grow well-aligned three-dimensional vanadium nitride (VN) nanowire arrays (NWAs) on carbon nanotube (CNT) fiber with an ultrahigh specific capacitance of 715 mF/cm 2 in a three-electrode system. Benefiting from their intriguing structural features, we successfully fabricated a prototype asymmetric coaxial FSS (ACFSS) with a maximum operating voltage of 1.8 V. From core to shell, this ACFSS consists of a CNT fiber core coated with VN@C NWAs as the negative electrode, Na 2 SO 4 poly(vinyl alcohol) (PVA) as the solid electrolyte, and MnO 2 /conducting polymer/CNT sheets as the positive electrode. The novel coaxial architecture not only fully enables utilization of the effective surface area and decreases the contact resistance between the two electrodes but also, more importantly, provides a short pathway for the ultrafast transport of axial electrons and ions. The electrochemical results show that the optimized ACFSS exhibits a remarkable specific capacitance of 213.5 mF/cm 2 and an exceptional energy density of 96.07 μWh/cm 2 , the highest areal capacitance and areal energy density yet reported in FSSs. Furthermore, the device possesses excellent flexibility in that its capacitance retention reaches 96.8% after bending 5000 times, which further allows it to be woven into flexible electronic clothes with conventional weaving techniques. Therefore, the asymmetric coaxial architectural design allows new opportunities to fabricate high-performance flexible FSSs for future portable and wearable electronic devices.

Electrochemical deposition of honeycomb magnetite on partially exfoliated graphite as anode for capacitive applications

NASA Astrophysics Data System (ADS)

Sun, Zhen; Cai, Xiang; Song, Yu; Liu, Xiao-Xia

2017-08-01

Research on anode materials with high capacitive performance is lagging behind that of cathode materials, which has severely hindered the development of high-efficient energy storage devices. Compared with other anode materials, Fe3O4 exhibits highly desirable advantages due to its low cost, high theoretical capacity and preferable electronic conductivity of ∼102 S cm-1. Herein, hierarchical honeycomb Fe3O4 is integrated on functionalized exfoliated graphite through electrochemical deposition and the following chemical conversion. The hierarchical honeycomb Fe3O4 is constructed by the oxide nanorods, which are assembled by a number of nanoparticles. This unique porous structure not only ensures fast ion diffusion in the electrode, but also provides large amount of active sites for electrochemical reactions. The exfoliated graphene atop the graphite base can act as 3D conductive scaffold to facilitate the electron transport of the electrode. Therefore, FEG/Fe3O4 exhibits large specific capacitances of 327 F g-1@1 A g-1 and 275 F g-1@10 A g-1. Good cycling stability is also achieved due to the flexibility of the graphene substrate. The assembled asymmetric device using FEG/Fe3O4 as anode can deliver a high energy density of 54 Wh kg-1.

N-enriched multilayered porous carbon derived from natural casings for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Zongying; Li, Yu; Li, Dandan; Wang, Dawei; Zhao, Jing; Wang, Zhifeng; Banis, Mohammad N.; Hu, Yongfeng; Zhang, Huaihao

2018-06-01

In this study, N-enriched multilayered porous activated carbon (LPAC), using natural casings as precursor, was fabricated by a facile carbonization and subsequent KOH activation procedure. The influence of the mass ratio of KOH to carbonized material on pore-structure and surface element composition of LPACs was investigated by a variety of means, such as SEM, HRTEM, BET, Raman, XRD, XPS and XAS. Owing to the unique multilayered texture and nitrogen (N) and oxygen (O) rich feature of natural casings, the resulting LPACs possess interconnected and developed porous structure with N- and O-enriched functional groups, contributing to larger pseudocapacitance. With the rise of mass ratio, the specific surface area (SSA) and average pore size of LPACs increased. The final materials were endowed with a desirable SSA (3100 m2 g-1) and high N content (6.34 at.%). Meanwhile, N- and O-enriched LPAC-4 exhibited a high specific capacitance (307.5 F g-1 at a current density of 0.5 A g-1 in 6 M KOH aqueous solution), excellent rate performance (63.4% capacitance retention at 20 A g-1) and good cycling stability (7.1% capacitance loss after 5000 cycles). Furthermore, the assembled symmetrical supercapacitor (LPAC-4//LPAC-4) with a wide voltage window of 1.4 V delivered a remarkable energy density of 11.6 Wh kg-1 at a power density of 297 W kg-1. These results suggested that unique LPACs derived from natural casings are a promising material for supercapacitors.

Monodisperse Carbon Nanospheres with Hierarchical Porous Structure as Electrode Material for Supercapacitor

NASA Astrophysics Data System (ADS)

Yang, Xiutao; Xia, Hui; Liang, Zhongguan; Li, Haiyan; Yu, Hongwen

2017-09-01

Carbon nanospheres with distinguishable microstructure were prepared by carbonization and subsequent KOH activation of F108/resorcinol-formaldehyde composites. The dosage of triblock copolymer Pluronic F108 is crucial to the microstructure differences. With the adding of F108, the polydisperse carbon nanospheres (PCNS) with microporous structure, monodisperse carbon nanospheres (MCNS) with hierarchical porous structure, and agglomerated carbon nanospheres (ACNS) were obtained. Their microstructure and capacitance properties were carefully compared. As a result of the synergetic effect of mono-dispersion spheres and hierarchical porous structures, the MCNS sample shows improved electrochemical performance, i.e., the highest specific capacitance of 224 F g-1 (0.2 A g-1), the best rate capability (73% retention at 20 A g-1), and the most excellent capacitance retention of 93% over 10,000 cycles, making it to be the promising electrode material for high-performance supercapacitors.

Silicon Carbide Capacitive High Temperature MEMS Strain Transducer

DTIC Science & Technology

2012-03-22

SILICON CARBIDE CAPACITIVE HIGH TEMPURATURE MEMS STRAIN TRANSDUCER THESIS Richard P. Weisenberger, DR01, USAF AFIT/GE/ENG...declared a work of the U.S. Government and is not subject to copyright protection in the United States AFIT/GE/ENG/12-43 SILICON CARBIDE CAPACITIVE...STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT/GE/ENG/12-43 SILICON CARBIDE CAPACITIVE IDGH TEMPURATURE MEMS STRAIN TRANSDUCER

Flexible Asymmetric Supercapacitors Based on Nitrogen-Doped Graphene Hydrogels with Embedded Nickel Hydroxide Nanoplates.

PubMed

Xie, Hao; Tang, Shaochun; Li, Dongdong; Vongehr, Sascha; Meng, Xiangkang

2017-05-22

To push the energy density limit of supercapacitors (SCs), new electrode materials with hierarchical nano-micron pore architectures are strongly desired. Graphene hydrogels that consist of 3 D porous frameworks have received particular attention but their capacitance is limited by electrical double layer capacitance. In this work, we report the rational design and fabrication of a composite hydrogel of N-doped graphene (NG) that contains embedded Ni(OH) 2 nanoplates that is cut conveniently into films to serve as positive electrodes for flexible asymmetric solid-state SCs with NG hydrogel films as negative electrodes. The use of high-power ultrasound leads to hierarchically porous micron-scale sheets that consist of a highly interconnected 3 D NG network in which Ni(OH) 2 nanoplates are well dispersed, which avoids the stacking of NG, Ni(OH) 2 , and their composites. The optimal SC device benefits from the compositional features and 3 D electrode architecture and has a high specific areal capacitance of 255 mF cm -2 at 1.0 mA cm -2 and a very stable, high output cell voltage of 1.45 V, which leads to an energy density of 80 μW h cm -2 even at a high power of 944 μW cm -2 , considerably higher than that reported for similar devices. The devices exhibit a high rate capability and only 8 % capacitance loss over 10 000 charging cycles as well as excellent flexibility with no clear performance degradation under strong bending. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nano ZnO-activated carbon composite electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Selvakumar, M.; Krishna Bhat, D.; Manish Aggarwal, A.; Prahladh Iyer, S.; Sravani, G.

2010-05-01

A symmetrical (p/p) supercapacitor has been fabricated by making use of nanostructured zinc oxide (ZnO)-activated carbon (AC) composite electrodes for the first time. The composites have been characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction analysis (XRD). Electrochemical properties of the prepared nanocomposite electrodes and the supercapacitor have been studied using cyclic voltammetry (CV) and AC impedance spectroscopy in 0.1 M Na 2SO 4 as electrolyte. The ZnO-AC nanocomposite electrode showed a specific capacitance of 160 F/g for 1:1 composition. The specific capacitance of the electrodes decreased with increase in zinc oxide content. Galvanostatic charge-discharge measurements have been done at various current densities, namely 2, 4, 6 and 7 mA/cm 2. It has been found that the cells have excellent electrochemical reversibility and capacitive characteristics in 0.1 M Na 2SO 4 electrolyte. It has also been observed that the specific capacitance is constant up to 500 cycles at all current densities.

Great improvement in pseudocapacitor properties of nickel hydroxide via simple gold deposition.

PubMed

Kim, Sun-I; Thiyagarajan, Pradheep; Jang, Ji-Hyun

2014-10-21

In this letter, we report a facile approach to improve the capacitor properties of nickel hydroxide (Ni(OH)2) by simply coating gold nanoparticles (Au NPs) on the surface of Ni(OH)2. Au NP-deposited Ni(OH)2 (Au/Ni(OH)2) has been prepared by application of a conventional colloidal coating of Au NPs on the surface of 3D-Ni(OH)2 synthesized via a hydrothermal method. Compared with pristine Ni(OH)2, Au/Ni(OH)2 shows a 41% enhanced capacitance value, excellent rate capacitance behavior at high current density conditions, and greatly improved cycling stability for supercapacitor applications. The specific capacitance of Au/Ni(OH)2 reached 1927 F g(-1) at 1 A g(-1), which is close to the theoretical capacitance and retained 66% and 80% of the maximum value at a high current density of 20 A g(-1) and 5000 cycles while that of pristine Ni(OH)2 was 1363 F g(-1) and significantly decreased to 48% and 30%, respectively, under the same conditions. The outstanding performance of Au/Ni(OH)2 as a supercapacitor is attributed to the presence of metal Au NPs on the surface of semiconductor Ni(OH)2; this permits the creation of virtual 3D conducting networks via metal/semiconductor contact, which induces fast electron and ion transport by acting as a bridge between Ni(OH)2 nanostructures, thus eventually leading to significantly improved electrochemical capacitive behaviors, as confirmed by the EIS and I-V characteristic data.

3D macroporous graphene frameworks for supercapacitors with high energy and power densities.

PubMed

Choi, Bong Gill; Yang, Minho; Hong, Won Hi; Choi, Jang Wook; Huh, Yun Suk

2012-05-22

In order to develop energy storage devices with high power and energy densities, electrodes should hold well-defined pathways for efficient ionic and electronic transport. Herein, we demonstrate high-performance supercapacitors by building a three-dimensional (3D) macroporous structure that consists of chemically modified graphene (CMG). These 3D macroporous electrodes, namely, embossed-CMG (e-CMG) films, were fabricated by using polystyrene colloidal particles as a sacrificial template. Furthermore, for further capacitance boost, a thin layer of MnO(2) was additionally deposited onto e-CMG. The porous graphene structure with a large surface area facilitates fast ionic transport within the electrode while preserving decent electronic conductivity and thus endows MnO(2)/e-CMG composite electrodes with excellent electrochemical properties such as a specific capacitance of 389 F/g at 1 A/g and 97.7% capacitance retention upon a current increase to 35 A/g. Moreover, when the MnO(2)/e-CMG composite electrode was asymmetrically assembled with an e-CMG electrode, the assembled full cell shows remarkable cell performance: energy density of 44 Wh/kg, power density of 25 kW/kg, and excellent cycle life.

Three-dimensional ordered macroporous MnO2/carbon nanocomposites as high-performance electrodes for asymmetric supercapacitors.

PubMed

Yang, Chunzhen; Zhou, Ming; Xu, Qian

2013-12-07

MnO2/carbon composites with ultrathin MnO2 nanofibers (diameter of 5-10 nm) uniformly deposited on three dimensional ordered macroporous (3DOM) carbon frameworks were fabricated via a self-limiting redox process. The MnO2 nanofibers provide a large surface area for charge storage, whereas the 3DOM carbon serves as a desirable supporting material providing rapid ion and electron transport through the composite electrodes. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) were used to characterize the capacitive performance of these composites. Optimization of the composition results in a composite with 57 wt% MnO2 content, which gives both a high specific capacitance (234 F g(-1) at a discharge current of 0.1 A g(-1)) and good rate capability (52% retention of the capacitance at 5 A g(-1)). An asymmetric supercapacitor was fabricated by assembling the optimized MnO2/carbon composite as the positive electrode and 3DOM carbon as the negative electrode. The asymmetric supercapacitor exhibits superior electrochemical performances, which can be reversibly charged and discharged at a maximum cell voltage of 2.0 V in 1.0 M Na2SO4 aqueous electrolyte, delivering both high energy density (30.2 W h kg(-1)) and power density (14.5 kW kg(-1)). Additionally, the asymmetric supercapacitor exhibits an excellent cycle life, with 95% capacitance retained after 1000 cycles.

Engineering hierarchical ultrathin CuCo2O4 nanosheets array on Ni foam by rapid electrodeposition method toward high-performance binder-free supercapacitors

NASA Astrophysics Data System (ADS)

Abbasi, Laleh; Arvand, Majid

2018-07-01

In the present work, we engineer hierarchical ultrathin CuCo2O4 nanosheets arrays on Ni foam through a facile, controllable and low-cost electrodeposition method by controlling deposition time and adjusting precursor's type, as a binder-free electrode for high performance supercapacitors. The effects of deposition time and types of precursors on the morphology of the as-prepared electrodes were investigated by X-ray diffraction, energy dispersive X-ray analysis, field-emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. As a results, the CuCo2O4 electrode prepared by nitrate salts at the deposition time of 10 min, includes the most uniform and ultrathin nanosheet arrays and exhibits the highest capacitance performance, such as ultrahigh specific capacitance of 1330 F g-1 at 2 A g-1 with 70% capacitance retention (938 F g-1) at ultrahigh current density of 60 A g-1, excellent cycling stability of 93.6% capacitance retention after 5000CD cycles and the maximum energy density of 29.55 Wh kg-1 at the power density of 0.4 kW kg-1. These superior electrochemical performances have been attributed to its unique structures with direct connected ultrathin nanosheets on the surface of Ni foam and abundant pores provide large electroactive sites for electrochemical reactions, as well as facile electron, ion transport and high electrical conductivity.

Hierarchically MnO2-Nanosheet Covered Submicrometer-FeCo2O4-Tube Forest as Binder-Free Electrodes for High Energy Density All-Solid-State Supercapacitors.

PubMed

Zhu, Baogang; Tang, Shaochun; Vongehr, Sascha; Xie, Hao; Meng, Xiangkang

2016-02-01

The current problem of the still relatively low energy densities of supercapacitors can be effectively addressed by designing electrodes hierarchically on micro- and nanoscale. Herein, we report the synthesis of hierarchically porous, nanosheet covered submicrometer tube forests on Ni foam. Chemical deposition and thermal treatment result in homogeneous forests of 750 nm diameter FeCo2O4 tubes, which after hydrothermal reaction in KMnO4 are wrapped in MnO2-nanosheet-built porous covers. The covers' thickness can be adjusted from 200 to 800 nm by KMnO4 concentration. An optimal thickness (380 nm) with a MnO2 content of 42 wt % doubles the specific capacitance (3.30 F cm(-2) at 1.0 mA cm(-2)) of the bare FeCo2O4-tube forests. A symmetric solid-state supercapacitor made from these binder-free electrodes achieves 2.52 F cm(-2) at 2 mA cm(-2), much higher than reported for capacitors based on similar core-shell nanowire arrays. The large capacitance and high cell voltage of 1.7 V allow high energy and power densities (93.6 Wh kg(-1), 10.1 kW kg(-1)). The device also exhibits superior rate capability (71% capacitance at 20 mA cm(-2)) and remarkable cycling stability with 94% capacitance retention being stable after 1500 cycles.

Microporous MOFs Engaged in the Formation of Nitrogen-Doped Mesoporous Carbon Nanosheets for High-Rate Supercapacitors.

PubMed

Hou, Ya-Nan; Zhao, Zongbin; Yu, Zhengfa; Zhang, Su; Li, Shaofeng; Yang, Juan; Zhang, Han; Liu, Chang; Wang, Zhiyu; Qiu, Jieshan

2018-02-21

Nitrogen-doped mesoporous carbon nanosheets (NMCS) have been fabricated from zinc-based microporous metal-organic frameworks (ZIF-8) by pyrolysis in a molten salt medium. The as-prepared NMCS exhibit significantly improved specific capacitance (NMCS-8: 232 F g -1 at 0.5 A g -1 ) and capacitance retention ratio (75.9 % at 50 A g -1 ) compared with the micropore-dominant nitrogen-doped porous carbon polyhedrons (NPCP-5: 178 F g -1 at 0.5 A g -1 , 15.9 % at 20 A g -1 ) obtained by direct pyrolysis of nanocrystalline ZIF-8. The excellent capacitive performance and high rate performance of the NMCS can be attributed to their unique combination of structure and composition, that is, the two-dimensional and hierarchically porous structure provides a short ion-transport pathway and facilitates the supply of electrolyte ions, and the nitrogen-doped polar surface improves the interface wettability when used as an electrode. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

High energy density asymmetric supercapacitors with a nickel oxide nanoflake cathode and a 3D reduced graphene oxide anode

NASA Astrophysics Data System (ADS)

Luan, Feng; Wang, Gongming; Ling, Yichuan; Lu, Xihong; Wang, Hanyu; Tong, Yexiang; Liu, Xiao-Xia; Li, Yat

2013-08-01

Here we demonstrate a high energy density asymmetric supercapacitor with nickel oxide nanoflake arrays as the cathode and reduced graphene oxide as the anode. Nickel oxide nanoflake arrays were synthesized on a flexible carbon cloth substrate using a seed-mediated hydrothermal method. The reduced graphene oxide sheets were deposited on three-dimensional (3D) nickel foam by hydrothermal treatment of nickel foam in graphene oxide solution. The nanostructured electrodes provide a large effective surface area. The asymmetric supercapacitor device operates with a voltage of 1.7 V and achieved a remarkable areal capacitance of 248 mF cm-2 (specific capacitance of 50 F g-1) at a charge/discharge current density of 1 mA cm-2 and a maximum energy density of 39.9 W h kg-1 (based on the total mass of active materials of 5.0 mg). Furthermore, the device showed an excellent charge/discharge cycling performance in 1.0 M KOH electrolyte at a current density of 5 mA cm-2, with a capacitance retention of 95% after 3000 cycles.

Engineering firecracker-like beta-manganese dioxides@spinel nickel cobaltates nanostructures for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Kuang, Min; Wen, Zhong Quan; Guo, Xiao Long; Zhang, Sheng Mao; Zhang, Yu Xin

2014-12-01

An effective and rational strategy is developed for large-scale growth of firecracker-like Ni-substituted Co3O4 (NiCo2O4) nanosheets on β-MnO2 nanowires (NWs) with robust adhesion as high-performance electrode for electrochemical capacitors. The NiCo2O4-MnO2 nanostructures display much higher specific capacitance (343 F g-1 at current density of 0.5 A g-1), better rate capability (75.3% capacitance retention from 0.5 A g-1 to 8 A g-1) and excellent cycle stability (5% capacitance loss after 3000 cycles) than Co3O4-MnO2 nanostructures. Moreover, an asymmetric supercapacitor based on NiCo2O4-MnO2 NWs as the positive electrode and activated graphenes (AG) as the negative electrode achieves an energy density of 9.4 Wh kg-1 and a maximum power density of 2.5 kW kg-1. These attractive findings suggest this novel core-shell nanostructure promising for electrochemical applications as an efficient supercapacitive electrode.

Carbonization-dependent nitrogen-doped hollow porous carbon nanospheres synthesis and electrochemical study for supercapacitors

NASA Astrophysics Data System (ADS)

Zhou, Lingyun; Xie, Guohong; Chen, Xiling

2018-05-01

In this paper, a nitrogen-doped hollow microporous carbon nanospheres was synthesized via the combination of hyper-crosslinking mediated self-assembly and further pyrolysis using polylactide-b-polystyrene (PLA-b-PS) copolymers and aniline monomers as precursor. The pore structure and the correlative electrochemical performance of nitrogen-doped hollow microporous carbon nanospheres were affected by the molar mass ratio of aniline and PS in block copolymers and the carbonization conditions. The electrochemical measurements results showed that the obtained PLA150-PS250-N4-900-10H sample with nitrogen content of 3.57% and the BET surface area of 945 m2 g-1 displays the best capacitance performance. At a current density of 1.0 Ag-1, the resultant specific capacitance is 250 Fg-1. In addition, it also exhibits high capacitance retention of 98% after charging-discharging 1500 times at 25 Ag-1. The results demonstrate the nitrogen-doped hollow microporous carbon nanospheres can be used as promising supercapacitor electrode materials for high performance energy storage devices.

Facile synthesis of Co(OH)2/Al(OH)3 nanosheets with improved electrochemical properties for asymmetric supercapacitor

NASA Astrophysics Data System (ADS)

Zhao, Cuimei; Ren, Fang; Cao, Yang; Xue, Xiangxin; Duan, Xiaoyue; Wang, Hairui; Chang, Limin

2018-01-01

Sheet-like Co(OH)2/Al(OH)3 or Co(OH)2 nanomaterial has been synthesized on conducting carbon fiber paper (CFP) by a facile one-step electrochemical deposition. The binder-free Co(OH)2/Al(OH)3/CFP displays an improved electrical conductivity, electrochemical activity and material utilization than solitary Co(OH)2, therefore Co(OH)2/Al(OH)3 nanomaterial exhibits improved electrochemical properties (a maximum capacitance of 1006 Fg-1 at 2 Ag-1, with 77% retention even at a high current density of 32 Ag-1, and more than 87% of the capacitance retention after 10000 cycles at 32 Ag-1) in comparison to that of the Co(OH)2/CFP (709 Fg-1, 65%, 79%). In addition, an asymmetric supercapacitor (ASC) fabricated with Co(OH)2/Al(OH)3/CFP positive electrode and AC/CFP negative electrode demonstrates ultrahigh specific capacitance (75.8 Fg-1) and potential window (1.7 V). These encouraging results make these low-cost and eco-friendly materials promising for high-performance energy storage application.

Insight into capacitive performance of polyaniline/graphene oxide composites with ecofriendly binder

NASA Astrophysics Data System (ADS)

Bilal, Salma; Fahim, Muhammad; Firdous, Irum; Ali Shah, Anwar-ul-Haq

2018-03-01

The behaviour of gold electrode modified with polyaniline/graphene oxide composites (PGO) was studied for electrochemical and charge storage properties in aqueous acidic media. The surface of gold electrode was modified with aqueous slurry of PGO by using Carboxymethyl cellulose (CMC) as binder. The intercalation of polyaniline in the GO layers, synthesized by in situ polymerization was confirmed by scanning electron microscopy (SEM). The electrochemical behaviour and charge storing properties were investigated using cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS). A high specific capacitance of 1721 F g-1 was obtained for PGO with 69.8% retention of capacitance even after 1000 voltammetric cycles in the potential range of 0-0.9 V at 20 mV s-1. EIS indicated low charge transfer resistance (Rct) and solution resistance (Rs) values of 0.51 Ω and 0.07 Ω, respectively. This good performance of PGO coated electrode is attributed to the use of CMC binder which generate a high electrode/ electrolyte contact area and short path lengths for electronic transport and electrolyte ion.

High energy density asymmetric supercapacitors with a nickel oxide nanoflake cathode and a 3D reduced graphene oxide anode.

PubMed

Luan, Feng; Wang, Gongming; Ling, Yichuan; Lu, Xihong; Wang, Hanyu; Tong, Yexiang; Liu, Xiao-Xia; Li, Yat

2013-09-07

Here we demonstrate a high energy density asymmetric supercapacitor with nickel oxide nanoflake arrays as the cathode and reduced graphene oxide as the anode. Nickel oxide nanoflake arrays were synthesized on a flexible carbon cloth substrate using a seed-mediated hydrothermal method. The reduced graphene oxide sheets were deposited on three-dimensional (3D) nickel foam by hydrothermal treatment of nickel foam in graphene oxide solution. The nanostructured electrodes provide a large effective surface area. The asymmetric supercapacitor device operates with a voltage of 1.7 V and achieved a remarkable areal capacitance of 248 mF cm(-2) (specific capacitance of 50 F g(-1)) at a charge/discharge current density of 1 mA cm(-2) and a maximum energy density of 39.9 W h kg(-1) (based on the total mass of active materials of 5.0 mg). Furthermore, the device showed an excellent charge/discharge cycling performance in 1.0 M KOH electrolyte at a current density of 5 mA cm(-2), with a capacitance retention of 95% after 3000 cycles.

Molecular modification of highly degenerate semiconductor as an active electrode to enhance the performance of supercapacitors

NASA Astrophysics Data System (ADS)

Mundinamani, S. P.; Rabinal, M. K.

2014-12-01

Highly conducting antimony doped tin oxide (SnO2:Sb) films are electrografted with suitable organic molecules to study their electrolytic behavior. A series of organic molecules, such as heptanethiol, dodecanethiol and octadecanethiol are bonded to electrode surfaces. Electrolytic capacitors were formed on both unmodified and chemically modified electrodes using KCl and H2SO4 as electrolytes. This molecular modification significantly enhances the current levels in cyclic voltammograms, and there is a clear shift in oxidation/reduction peaks of these capacitors with scan rate. The results obey Randles-Sevcik relation, which indicates that there is enhancement of ionic diffusion at the electrode-electrolyte interface. There is a large enhancement in the values of specific capacitance (almost by 104 times) after the chemical modification. These measurements show that Faradaic reactions are responsible for charge storage/discharge process in these capacitors. Hence, the molecularly modified electrodes can be a good choice to increase the specific capacitance.

Engineering hierarchical Diatom@CuO@MnO2 hybrid for high performance supercapacitor

NASA Astrophysics Data System (ADS)

Zhang, Yan; Guo, Wan Wan; Zheng, Tian Xu; Zhang, Yu Xin; Fan, Xing

2018-01-01

A rational and hierarchical Diatom@CuO@MnO2 hybrid was fabricated via a facile electroless copper plating technology, following by a one-pot hydrothermal reaction with KMnO4. Such unique architecture acts as a supercapacitor electrode, which exhibits a high specific capacitance (240 F g-1 at a current density of 0.5 A g-1), good rate capability (58.3% retention when the current density increases from 0.5 to 5 A g-1), and excellent electrochemical cycling stability (91.2% retention of the initial specific capacitance after 4000 cycles at a current density of 2 A g-1). The impressive electrochemical performance of this Diatom@CuO@MnO2 electrode ascribed to the synergistic effect between the CuO particles and MnO2 nanosheets. Therefore, it can be expected that this unique Diatom@CuO@MnO2 electrode may have great promise for the application in supercapacitors.