Science.gov

Sample records for electrolyte li doped

  1. Li-Doped Ionic Liquid Electrolytes: From Bulk Phase to Interfacial Behavior

    NASA Technical Reports Server (NTRS)

    Haskins, Justin B.; Lawson, John W.

    2016-01-01

    Ionic liquids have been proposed as candidate electrolytes for high-energy density, rechargeable batteries. We present an extensive computational analysis supported by experimental comparisons of the bulk and interfacial properties of a representative set of these electrolytes as a function of Li-salt doping. We begin by investigating the bulk electrolyte using quantum chemistry and ab initio molecular dynamics to elucidate the solvation structure of Li(+). MD simulations using the polarizable force field of Borodin and coworkers were then performed, from which we obtain an array of thermodynamic and transport properties. Excellent agreement is found with experiments for diffusion, ionic conductivity, and viscosity. Combining MD simulations with electronic structure computations, we computed the electrochemical window of the electrolytes across a range of Li(+)-doping levels and comment on the role of the liquid environment. Finally, we performed a suite of simulations of these Li-doped electrolytes at ideal electrified interfaces to evaluate the differential capacitance and the equilibrium Li(+) distribution in the double layer. The magnitude of differential capacitance is in good agreement with our experiments and exhibits the characteristic camel-shaped profile. In addition, the simulations reveal Li(+) to be highly localized to the second molecular layer of the double layer, which is supported by additional computations that find this layer to be a free energy minimum with respect to Li(+) translation.

  2. Electrical analysis of amorphous corn starch-based polymer electrolyte membranes doped with LiI

    NASA Astrophysics Data System (ADS)

    Shukur, M. F.; Ibrahim, F. M.; Majid, N. A.; Ithnin, R.; Kadir, M. F. Z.

    2013-08-01

    In this work, polymer electrolytes have been prepared by doping starch with lithium iodide (LiI). The incorporation of 30 wt% LiI optimizes the room temperature conductivity of the electrolyte at (1.83 ± 0.47) × 10-4 S cm-1. Further conductivity enhancement to (9.56 ± 1.19) × 10-4 S cm-1 is obtained with the addition of 30 wt% glycerol. X-ray diffraction analysis indicates that the conductivity enhancement is due to the increase in amorphous content. The activation energy, Ea, of 70 wt% starch-30 wt% LiI electrolyte is 0.26 eV, while 49 wt% starch-21 wt% LiI-30 wt% glycerol electrolyte exhibits an Ea of 0.16 eV. Dielectric studies show that all the electrolytes obey non-Debye behavior. The power law exponent s is obtained from the variation of dielectric loss, ɛi, with frequency at different temperatures. The conduction mechanism of 70 wt% starch-30 wt% LiI electrolyte can be explained by the correlated barrier hopping model, while the conduction mechanism for 49 wt% starch-21 wt% LiI-30 wt% glycerol electrolyte can be represented by the quantum mechanical tunneling model.

  3. Optical and dielectric properties of TiO2 doped PVA-CN/LiClO4 composite electrolyte

    NASA Astrophysics Data System (ADS)

    Rathod, Sunil G.; Bhajantri, R. F.; Ravindrachary, V.; Pujari, P. K.; Sheela, T.

    2013-02-01

    Solid polymer electrolyte (SPE) composite films of PVA-CN-HOBt-LiClO4 doped with TiO2 were prepared by solution casting method. The films were characterized using FT-IR, UV-Vis, DSC and Dielectric studies at room temperature. The FTIR results show the interaction of TiO2 nanoparticles with PVA-CN-HOBt-LiClO4 composite. The optical absorbance of the composite films increases from 250nm to 400nm with increase in doping and optical band gap (Eg) decreases from 3.2eV to 3.1eV. The glass transition temperature increases with increase in doping level. The dielectric properties of the composites show that these composite films can be used for SPE nanocomposites.

  4. Investigation of Structure and Transport in Li-Doped Ionic Liquid Electrolytes: [pyr14][TFSI], [pyr13][FSI], [EMIM][BF4

    NASA Technical Reports Server (NTRS)

    Haskins, Justin B.; Bennett, William R.; Wu, James J.; Hernandez, Dionne M.; Borodin, Oleg; Monk, Joshua D.; Bauschlicher, Charles W., Jr.; Lawson, John W.

    2014-01-01

    Ionic liquid electrolytes have been proposed as a means of improving the safety and cycling behavior of advanced lithium batteries; however, the properties of these electrolytes under high lithium doping are poorly understood. Here, we employ both polarizable molecular dynamics simulation and experiment to investigate the structure, thermodynamics and transport of three potential electrolytes, N-methyl-N-butylpyrrolidinium bis(trifluoromethylsufonyl)imide ([pyr14][TFSI]), N- methyl-N-propylpyrrolidinium bis(fluorosufonyl)imide ([pyr13][FSI]), and 1-ethyl-3-- methylimidazolium boron tetrafluoride ([EMIM][BF4]), as a function of Li (-) salt concentration and temperature. Structurally, Li(+) is shown to be solvated by three anion neighbors in [pyr14][TFSI] and four anion neighbors in both [pyr13][FSI] and [EMIM][BF4], and at all levels of xLi we find the presence of lithium aggregates. Furthermore, the computed density, diffusion, viscosity, and ionic conductivity show excellent agreement with experimental data. While the diffusion and viscosity exhibit a systematic decrease and increase, respectively, with increasing xLi, the contribution of Li(+) to ionic conductivity increases until reaching a saturation doping level of xLi 0.10. Comparatively, the Li(+) conductivity of [pyr14][TFSI] is an order of magnitude lower than that of the other liquids, which range between 0.1-0.3 mScm. The differences in Li(+) transport are reflected in the residence times of Li(+) with the anions, which are revealed to be much larger for [pyr14][TFSI] (up to 100 ns at the highest doping levels) than in either [EMIM][BF4] or [pyr13][FSI]. Finally, we comment on the relative kinetics of Li(+) transport in each liquid and we present strong evidence for transport through anion exchange (hopping) as opposed to the net motion of Li(+) with its solvation shell (vehicular).

  5. Investigation of Structure and Transport in Li-Doped Ionic Liquid Electrolytes: [pyr14][TFSI], [pyr13][FSI] and [EMIM][BF4

    NASA Technical Reports Server (NTRS)

    Haskins, Justin B.; Bennett, William R.; Hernandez-Lugo, Dione M.; Wu, James; Borodin, Oleg; Monk, Joshua D.; Bauschlicher, Charles W.; Lawson, John W.

    2014-01-01

    Ionic liquid electrolytes have been proposed as a means of improving the safety and cycling behavior of advanced lithium batteries; however, the properties of these electrolytes under high lithium doping are poorly understood. Here, we employ both polarizable molecular dynamics simulation and experiment to investigate the structure, thermodynamics and transport of three potential electrolytes, N-methyl-Nbutylpyrrolidinium bis(trifluoromethylsufonyl)imide ([pyr14][TFSI]), N- methyl-Npropylpyrrolidinium bis(fluorosufonyl)imide ([pyr13][FSI]), and 1-ethyl-3-- methylimidazolium boron tetrafluoride ([EMIM][BF4]), as a function of Li-salt concentration and temperature. Structurally, Li(+) is shown to be solvated by three anion neighbors in [pyr14][TFSI] and four anion neighbors in both [pyr13][FSI] and [EMIM][BF4], and at all levels of x(sub Li) we find the presence of lithium aggregates. Furthermore, the computed density, diffusion, viscosity, and ionic conductivity show excellent agreement with experimental data. While the diffusion and viscosity exhibit a systematic decrease and increase, respectively, with increasing x(sub Li), the contribution of Li(+) to ionic conductivity increases until reaching a saturation doping level of x(sub Li) is approximately 0.10. Comparatively, the Li(+) conductivity of [pyr14][TFSI] is an order of magnitude lower than that of the other liquids, which range between 0.1 - 0.3 mS/cm. The differences in Li(+) transport are reflected in the residence times of Li(+) with the anions, which are revealed to be much larger for [pyr14][TFSI] (up to 100 ns at the highest doping levels) than in either [EMIM][BF4] or [pyr13][FSI]. Finally, we comment on the relative kinetics of Li(+) transport in each liquid and we present strong evidence for transport through anion exchange (hopping) as opposed to the net motion of Li(+) with its solvation shell (vehicular).

  6. Integrated study of first principles calculations and experimental measurements for Li-ionic conductivity in Al-doped solid-state LiGe2(PO4)3 electrolyte

    NASA Astrophysics Data System (ADS)

    Kang, Joonhee; Chung, Habin; Doh, Chilhoon; Kang, Byoungwoo; Han, Byungchan

    2015-10-01

    Understanding of the fundamental mechanisms causing significant enhancement of Li-ionic conductivity by Al3+ doping to a solid LiGe2(PO4)3 (LGP) electrolyte is pursued using first principles density functional theory (DFT) calculations combined with experimental measurements. Our results indicate that partial substitution Al3+ for Ge4+ in LiGe2(PO4)3 (LGP) with aliovalent (Li1+xAlxGe2-x(PO4)3, LAGP) improves the Li-ionic conductivity about four-orders of the magnitude. To unveil the atomic origin we calculate plausible diffusion paths of Li in LGP and LAGP materials using DFT calculations and a nudged elastic band method, and discover that LAGP had additional transport paths for Li with activation barriers as low as only 34% of the LGP. Notably, these new atomic channels manifest subtle electrostatic environments facilitating cooperative motions of at least two Li atoms. Ab-initio molecular dynamics predict Li-ionic conductivity for the LAGP system, which is amazingly agreed experimental measurement on in-house made samples. Consequently, we suggest that the excess amounts of Li caused by the aliovalent Al3+ doping to LGP lead to not only enhancing Li concentration but also opening new conducting paths with substantially decreases activation energies and thus high ionic conductivity of LAGP solid-state electrolyte.

  7. Conductivity studies of LiCF3SO3 doped PVA: PVdF blend polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Tamilselvi, P.; Hema, M.

    2014-03-01

    Different composition of lithium ion conducting PVA: PVdF: Lithium triflate (LiCF3SO3) polymer electrolytes have been prepared by solution casting technique. Dielectric and conductivity studies have been carried out for the prepared samples. The addition of salt into the polymer matrix increases the ionic conductivity of blend polymer electrolytes. The conductivity analysis reveals 80PVA: 20PVdF: 15LiCF3SO3 polymer electrolyte exhibits the maximum ionic conductivity of 2.7×10-3 S cm-1 at 303 K. The temperature dependence of ionic conductivity for all the composition of PVA: PVdF: LiCF3SO3 polymer films obey Arrhenius relation. Low activation energy has been obtained for highest conducting sample. The dielectric spectra show absolute β-relaxation peak.

  8. Enhancement of lithium ion conductivity by doping Li3BO3 in Li2S-P2S5 glass-ceramics electrolytes for all-solid-state batteries

    NASA Astrophysics Data System (ADS)

    Eom, Minyong; Choi, Sunho; Son, Seunghyeon; Choi, Lakyoung; Park, Chanhwi; Shin, Dongwook

    2016-11-01

    (100-x) (0.78Li2S·0.22P2S5)·xLi3BO3 (0 ≤ x ≤ 5) solid electrolytes are prepared via mechanical milling and a post heat-treatment process, and the resulting electrochemical properties are investigated in conjunction with structural analysis. Adding of Li3BO3 into the (100-x) (0.78Li2S·0.22P2S5)·xLi3BO3 solid electrolyte is expected to enhance the conductivity and lower the activation energy as a consequence of changing the structural unit in the glass network. It turned out that the doping of Li3BO3 enhances the conductivity by enlarging the glass forming region and promoting precipitation of high lithium ion conductive thio-LISICON II analog. 97 (0.78Li2S·0.22P2S5)·3Li3BO3 (x = 3) glass-ceramics exhibits the highest conductivity (1.03 × 10-3 S cm-1). Structural analysis shows that the samples with Li3BO3 added to the electrolyte are composed of the main structural unit of PS43- with partially-modified structural unit of PO43-, which are believed to effectively enhance the conductivity and decrease the activation energy. In glass-ceramics produced from these materials, the thio-LISICON II phase with higher ionic conductivity tends to be stabilized by the addition of Li3BO3. Additionally, the formation of space-charge layer is relaxed by Li3BO3 doping. As a result, the all-solid-state cell shows high initial discharge capacity of 156 mAh g-1, and the capacity is retained to be 149 mAh g-1 for 40 cycles.

  9. A New Sealed Lithium-Peroxide Battery with a Co-Doped Li2O Cathode in a Superconcentrated Lithium Bis(fluorosulfonyl)amide Electrolyte

    NASA Astrophysics Data System (ADS)

    Okuoka, Shin-Ichi; Ogasawara, Yoshiyuki; Suga, Yosuke; Hibino, Mitsuhiro; Kudo, Tetsuichi; Ono, Hironobu; Yonehara, Koji; Sumida, Yasutaka; Yamada, Yuki; Yamada, Atsuo; Oshima, Masaharu; Tochigi, Eita; Shibata, Naoya; Ikuhara, Yuichi; Mizuno, Noritaka

    2014-07-01

    We propose a new sealed battery operating on a redox reaction between an oxide (O2-) and a peroxide (O22-) with its theoretical specific energy of 2570 Wh kg-1 (897 mAh g-1, 2.87 V) and demonstrate that a Co-doped Li2O cathode exhibits a reversible capacity over 190 mAh g-1, a high rate capability, and a good cyclability with a superconcentrated lithium bis(fluorosulfonyl)amide electrolyte in acetonitrile. The reversible capacity is largely dominated by the O2-/O22- redox reaction between oxide and peroxide with some contribution of the Co2+/Co3+ redox reaction.

  10. Samarium doped ceria-(Li/Na) 2CO 3 composite electrolyte and its electrochemical properties in low temperature solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Di, Jing; Chen, Mingming; Wang, Chengyang; Zheng, Jiaming; Fan, Liangdong; Zhu, Bin

    A composite of samarium doped ceria (SDC) and a binary carbonate eutectic (52 mol% Li 2CO 3/48 mol% Na 2CO 3) is investigated with respect to its morphology, conductivity and fuel cell performances. The morphology study shows the composition could prevent SDC particles from agglomeration. The conductivity is measured under air, argon and hydrogen, respectively. A sharp increase in conductivity occurs under all the atmospheres, which relates to the superionic phase transition in the interface phases between SDC and carbonates. Single cells with the composite electrolyte are fabricated by a uniaxial die-press method using NiO/electrolyte as anode and lithiated NiO/electrolyte as cathode. The cell shows a maximum power density of 590 mW cm -2 at 600 °C, using hydrogen as the fuel and air as the oxidant. Unlike that of cells based on pure oxygen ionic conductor or pure protonic conductor, the open circuit voltage of the SDC-carbonate based fuel cell decreases with an increase in water content of either anodic or cathodic inlet gas, indicating the electrolyte is a co-ionic (H +/O 2-) conductor. The results also exhibit that oxygen ionic conductivity contributes to the major part of the whole conductivity under fuel cell circumstances.

  11. A New Sealed Lithium-Peroxide Battery with a Co-Doped Li2O Cathode in a Superconcentrated Lithium Bis(fluorosulfonyl)amide Electrolyte

    PubMed Central

    Okuoka, Shin-ichi; Ogasawara, Yoshiyuki; Suga, Yosuke; Hibino, Mitsuhiro; Kudo, Tetsuichi; Ono, Hironobu; Yonehara, Koji; Sumida, Yasutaka; Yamada, Yuki; Yamada, Atsuo; Oshima, Masaharu; Tochigi, Eita; Shibata, Naoya; Ikuhara, Yuichi; Mizuno, Noritaka

    2014-01-01

    We propose a new sealed battery operating on a redox reaction between an oxide (O2−) and a peroxide (O22−) with its theoretical specific energy of 2570 Wh kg−1 (897 mAh g−1, 2.87 V) and demonstrate that a Co-doped Li2O cathode exhibits a reversible capacity over 190 mAh g−1, a high rate capability, and a good cyclability with a superconcentrated lithium bis(fluorosulfonyl)amide electrolyte in acetonitrile. The reversible capacity is largely dominated by the O2−/O22− redox reaction between oxide and peroxide with some contribution of the Co2+/Co3+ redox reaction. PMID:25023009

  12. A new sealed lithium-peroxide battery with a co-doped Li2O cathode in a superconcentrated lithium bis(fluorosulfonyl)amide electrolyte.

    PubMed

    Okuoka, Shin-ichi; Ogasawara, Yoshiyuki; Suga, Yosuke; Hibino, Mitsuhiro; Kudo, Tetsuichi; Ono, Hironobu; Yonehara, Koji; Sumida, Yasutaka; Yamada, Yuki; Yamada, Atsuo; Oshima, Masaharu; Tochigi, Eita; Shibata, Naoya; Ikuhara, Yuichi; Mizuno, Noritaka

    2014-07-14

    We propose a new sealed battery operating on a redox reaction between an oxide (O(2-)) and a peroxide (O2(2-)) with its theoretical specific energy of 2570 Wh kg(-1) (897 mAh g(-1), 2.87 V) and demonstrate that a Co-doped Li2O cathode exhibits a reversible capacity over 190 mAh g(-1), a high rate capability, and a good cyclability with a superconcentrated lithium bis(fluorosulfonyl)amide electrolyte in acetonitrile. The reversible capacity is largely dominated by the O(2-)/O2(2-) redox reaction between oxide and peroxide with some contribution of the Co(2+)/Co(3+) redox reaction.

  13. Computational and Experimental Investigation of Li-doped Ionic Liquid Electrolytes: [pyr14][tfsi], [pyr13][fsi], and [EMIM][BF4

    NASA Technical Reports Server (NTRS)

    Haskins, Justin B.; Bennett, William R.; Wu, James J.; Hernandez, Dionne M.; Borodin, Oleg; Monk, Joshua D.; Bauschlicher, Charles W.; Lawson, John W.

    2014-01-01

    We employ molecular dynamics (MD) simulation and experiment to investigate the structure, thermodynamics, and transport of N-methyl-N-butylpyrrolidinium bis(trifluoromethylsufonyl)imide ([pyr14][TFSI]), N -methyl-N-propylpyrrolidinium bis(fluorosufonyl)imide ([pyr13][FSI]), and 1-ethyl-3-methylimidazolium boron tetrafluoride ([EMIM][BF4]), as a function of Li-salt mole fraction (0.05 xLi+ 0.33) and temperature (298 K T 393 K). Structurally, Li+ is shown to be solvated by three anion neigh- bors in [pyr14][TFSI] and four anion neighbors in both [pyr13][FSI] and [EMIM][BF4], and at all levels of xLi+ we find the presence of lithium aggregates. Pulsed field gradient spin-echo NMR measurements of diffusion and electrochemical impedance spectroscopy measurements of ionic conductivity are made for the neat ionic liquids as well as 0.5 molal solutions of Li-salt in the ionic liquids. Bulk ionic liquid properties (density, diffusion, viscosity, and ionic conductivity) are obtained with MD and show excellent agreement with experiment. While the diffusion exhibits a systematic decrease with increasing xLi+, the contribution of Li+ to ionic conductivity increases until reach- ing a saturation doping level of xLi+ 0.10. Comparatively, the Li+ conductivity of [pyr14][TFSI] is an order of magnitude lower than that of the other liquids, which range between 0.1-0.3 mScm. Our transport results also demonstrate the necessity of long MD simulation runs ( 200 ns) required to converge transport properties at room T. The differences in Li+ transport are reflected in the residence times of Li+ with the anions (Li), which are revealed to be much larger for [pyr14][TFSI] (up to 100 ns at the highest doping levels) than in either [EMIM][BF4] or [pyr13][FSI]. Finally, to comment on the relative kinetics of Li+ transport in each liquid, we find that while the net motion of Li+ with its solvation shell (vehicular) significantly contributes to net diffusion in all liquids, the importance of

  14. Fluorine-doped antiperovskite electrolyte for all-solid-state Lithium-ion batteries

    SciTech Connect

    Li, Yutao; Zhou, Weidong; Xin, Sen; Li, Shuai; Zhu, Jinlong; Lu, Xujie; Cui, Zhiming; Jia, Quanxi; Zhou, Jianshi; Zhao, Yusheng; Goodenough, John B.

    2016-06-30

    A fluorine-doped antiperovskite Li-ion conducto Li2(OH)X (X=Cl, Br) is shown to be a promising candidat for a solid electrolyte in an all-solid-state Li-ion rechargeabl battery. Substitution of F¯ for OH¯ transforms orthorhombi Li2OHCl to a room-temperature cubic phase, which show electrochemical stability to 9 V versus Li+/Li and two orders o magnitude higher Li-ion conductivity than that of orthorhombi Li2OHCl. As a result, an all-solid-state Li/LiFePO4 with F-dope Li2OHCl as the solid electrolyte showed good cyclability an a high coulombic efficiency over 40 charge/discharge cycles

  15. Fluorine-Doped Antiperovskite Electrolyte for All-Solid-State Lithium-Ion Batteries.

    PubMed

    Li, Yutao; Zhou, Weidong; Xin, Sen; Li, Shuai; Zhu, Jinlong; Lü, Xujie; Cui, Zhiming; Jia, Quanxi; Zhou, Jianshi; Zhao, Yusheng; Goodenough, John B

    2016-08-16

    A fluorine-doped antiperovskite Li-ion conductor Li2 (OH)X (X=Cl, Br) is shown to be a promising candidate for a solid electrolyte in an all-solid-state Li-ion rechargeable battery. Substitution of F(-) for OH(-) transforms orthorhombic Li2 OHCl to a room-temperature cubic phase, which shows electrochemical stability to 9 V versus Li(+) /Li and two orders of magnitude higher Li-ion conductivity than that of orthorhombic Li2 OHCl. An all-solid-state Li/LiFePO4 with F-doped Li2 OHCl as the solid electrolyte showed good cyclability and a high coulombic efficiency over 40 charge/discharge cycles.

  16. Fluorine-doped antiperovskite electrolyte for all-solid-state Lithium-ion batteries

    DOE PAGES

    Li, Yutao; Zhou, Weidong; Xin, Sen; ...

    2016-06-30

    A fluorine-doped antiperovskite Li-ion conducto Li2(OH)X (X=Cl, Br) is shown to be a promising candidat for a solid electrolyte in an all-solid-state Li-ion rechargeabl battery. Substitution of F¯ for OH¯ transforms orthorhombi Li2OHCl to a room-temperature cubic phase, which show electrochemical stability to 9 V versus Li+/Li and two orders o magnitude higher Li-ion conductivity than that of orthorhombi Li2OHCl. As a result, an all-solid-state Li/LiFePO4 with F-dope Li2OHCl as the solid electrolyte showed good cyclability an a high coulombic efficiency over 40 charge/discharge cycles

  17. Rheological studies of PMMA-PVC based polymer blend electrolytes with LiTFSI as doping salt.

    PubMed

    Liew, Chiam-Wen; Durairaj, R; Ramesh, S

    2014-01-01

    In this research, two systems are studied. In the first system, the ratio of poly (methyl methacrylate) (PMMA) and poly (vinyl chloride) (PVC) is varied, whereas in the second system, the composition of PMMA-PVC polymer blends is varied with dopant salt, lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) with a fixed ratio of 70 wt% of PMMA to 30 wt% of PVC. Oscillation tests such as amplitude sweep and frequency sweep are discussed in order to study the viscoelastic properties of samples. Elastic properties are much higher than viscous properties within the range in the amplitude sweep and oscillatory shear sweep studies. The crossover of G' and G'' is absent. Linear viscoelastic (LVE) range was further determined in order to perform the frequency sweep. However, the absence of viscous behavior in the frequency sweep indicates the solid-like characteristic within the frequency regime. The viscosity of all samples is found to decrease as shear rate increases.

  18. Rheological Studies of PMMA–PVC Based Polymer Blend Electrolytes with LiTFSI as Doping Salt

    PubMed Central

    Liew, Chiam–Wen; Durairaj, R.; Ramesh, S.

    2014-01-01

    In this research, two systems are studied. In the first system, the ratio of poly (methyl methacrylate) (PMMA) and poly (vinyl chloride) (PVC) is varied, whereas in the second system, the composition of PMMA–PVC polymer blends is varied with dopant salt, lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) with a fixed ratio of 70 wt% of PMMA to 30 wt% of PVC. Oscillation tests such as amplitude sweep and frequency sweep are discussed in order to study the viscoelastic properties of samples. Elastic properties are much higher than viscous properties within the range in the amplitude sweep and oscillatory shear sweep studies. The crossover of and is absent. Linear viscoelastic (LVE) range was further determined in order to perform the frequency sweep. However, the absence of viscous behavior in the frequency sweep indicates the solid-like characteristic within the frequency regime. The viscosity of all samples is found to decrease as shear rate increases. PMID:25051241

  19. Solubility of Li/sub 2/S in LiF-LiCl-LiBr electrolyte: measurements and calculations

    SciTech Connect

    Tomczuk, Z.; Vissers, D.R.; Saboungi, M.L.

    1983-01-01

    High performance lithium-alloy/iron sulfide cells are currently being developed at Argonne National Laboratory and at several industrial firms for electric vehicle propulsion. These cells operate at high temperatures and utilize Li-Al or Li-Si negative electrodes, FeS positive electrodes, and a molten salt electrolyte. In the early work, the molten salt was the LiCl-KCl eutectic (58.2 mol % LiCl-41.8 mol % KCl), but in recent work various electrolyte compositions have been used, i.e., LiCl-rich LiCl--KCl (typically 67 mole % LiCl), LiF-LiCl-KCl, or LiF-LiCl-LiBr (1). The use of these electrolytes requires cell operating temperatures in the range of 703-773 K. As these cells are cycled, it has been shown that, when LiCl-KCl electrolytes were used, local electrolyte compositional changes occurred because of ion transport processes and chemical reactions in the cells. However, despite the temperature or the nature of the electrolyte, iron and lithium sulfide are the final discharge products. Thus, a systematic investigation of the solubility of Li/sub 2/S in a variety of electrolytes containing LiCl as a function of temperature is of technological importance in the development of these cells. We report new solubility measurements of Li/sub 2/S in the LiF-LiCl--LiBr eutectic solution (22 mol %-31 mol %-47 mol %) at 739 and 773 K. The observed increase of Li/sub 2/S solubility as the solvent is changed from LiCl-KCl to LiF-LiCl-LiBr and then to LiF-LiCl is explained in terms of known molten salt theories.

  20. Composite Solid Electrolyte Containing Li+- Conducting Fibers

    NASA Technical Reports Server (NTRS)

    Appleby, A. John; Wang, Chunsheng; Zhang, Xiangwu

    2006-01-01

    Improved composite solid polymer electrolytes (CSPEs) are being developed for use in lithium-ion power cells. The matrix components of these composites, like those of some prior CSPEs, are high-molecular-weight dielectric polymers [generally based on polyethylene oxide (PEO)]. The filler components of these composites are continuous, highly-Li(+)-conductive, inorganic fibers. PEO-based polymers alone would be suitable for use as solid electrolytes, were it not for the fact that their room-temperature Li(+)-ion conductivities lie in the range between 10(exp -6) and 10(exp -8) S/cm, too low for practical applications. In a prior approach to formulating a CSPE, one utilizes nonconductive nanoscale inorganic filler particles to increase the interfacial stability of the conductive phase. The filler particles also trap some electrolyte impurities. The achievable increase in conductivity is limited by the nonconductive nature of the filler particles.

  1. Composite Solid Electrolyte for Li Battery Applications

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, G.; Attia, A. I.; Halpert, G.; Peled, E.

    1993-01-01

    The electrochemical, bulk and interfacial properties of the polyethylene oxide (PEO) based composite solid electrolyte (CSE) comprising LiI, PEO, and Al2O3 have been evaluated for Li battery applications. The bulk interfacial and transport properties of the CSEs seem to strongly depend on the alumina particle size. For the CSE films with 0.05 micron alumina while the bulk conductivity is around 10(exp -4) (mho/cm) at 103 C, the Li ion transport number seems to be close to unity at the same temperature. Compared to the PEO electrolyte this polymer composite electrolyte seems to exhibit robust mechanical and interfacial properties. We have studied three different films with three different alumina sizes in the range 0.01-0.3 micron. Effects of Al2O3 particle size on the electrochemical performance of polymer composite electrolyte is discussed. With TiS2 as cathode a 10 mAh small capacity cell was charged and discharged at C/40 and C/20 rates respectively.

  2. Effect of co-doping nano-silica filler and N-methyl- N-propylpiperidinium bis(trifluoromethanesulfonyl)imide into polymer electrolyte on Li dendrite formation in Li/poly(ethylene oxide)-Li(CF 3SO 2) 2N/Li

    NASA Astrophysics Data System (ADS)

    Liu, S.; Wang, H.; Imanishi, N.; Zhang, T.; Hirano, A.; Takeda, Y.; Yamamoto, O.; Yang, J.

    Lithium metal dendrite growth in Li/poly (ethylene oxide)-lithium bis (trifluoromethanesulfonyl) imide (PEO 18LiTFSI), nano-silica, and N-methyl- N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI) composite solid polymer electrolyte/Li was investigated by direct in situ observation. The dendrite onset time decreased with increasing current density and deviated from Sand's law in the current density range of 0.1-0.5 mA cm -2 at 60 °C. Lithium dendrite formation was not observed until 46 h of polarization at 0.5 mA cm -2 and 60 °C, which is a significant improvement compared to that observed in Li/(PEO 18LiTFSI)/Li, where the dendrite formation was observed after 15 h polarization at 0.5 mA cm -2 and 60 °C. The suppression of dendrite formation could be explained by the electrical conductivity enhancement and decrease of the interface resistance between Li and the polymer electrolyte by the introduction of both nano-SiO 2 and PP13TFSI into PEO 18LiTFSI. The electrical conductivity of 4.96 × 10 -4 S cm -1 at 60 °C was enhanced to 7.6 × 10 -4 S cm -1, and the interface resistance of Li/PEO 18LiTFSI/Li of 248 Ω cm 2 was decreased to 74 Ω cm 2 by the addition of both nano-SiO 2 and PP13TFSI into PEO 18LiTFSI.

  3. Endurance testing with Li/Na electrolyte

    SciTech Connect

    Ong, E.T.; Remick, R.J.; Sishtla, C.I.

    1996-12-31

    The Institute of Gas Technology (IGT), under subcontract to M-C Power Corporation under DOE funding, has been operating bench-scale fuel cells to investigate the performance and endurance issues of the Li/Na electrolyte because it offers higher ionic conductivity, higher exchange current densities, lower vapor pressures, and lower cathode dissolution rates than the Li/K electrolyte. These cells have continued to show higher performance and lower decay rates than the Li/K cells since the publication of our two previous papers in 1994. In this paper, test results of two long-term 100-cm{sup 2} bench scale cells are discussed. One cell operated continuously at 160 mA/cm{sup 2} for 17,000 hours with reference gases (60H{sub 2}/20CO{sub 2}/20H{sub 2}O fuel at 75% utilization and 30CO{sub 2}/70 air oxidant humidified at room temperature at 50% utilization). The other cell operated at 160 mA/cm{sup 2} for 6900 hours at 3 atm with system gases (64H{sub 2}/16CO{sub 2}/20H{sub 2}O at 75% utilization and an M-C Power system-defined oxidant at 40% utilization). Both cells have shown the highest performance and longest endurance among IGT cells operated to date.

  4. High performance MCFC using Li/Na electrolyte

    SciTech Connect

    Donado, R.A.; Ong, E.T.; Sishtla, C.I.

    1995-08-01

    The substitution of a lithium/ sodium carbonate (Li/Na) mixture for the lithium/potassium carbonate (Li/K) electrolyte used in MCFCs holds the promise of higher ionic conductivity, higher exchange current density at both electrodes, lower vapor pressure, and lower cathode dissolution rates. However, when the substitution is made in cells optimized for use with the Li/K electrolyte, the promised increase in performance is not realized. As a consequence the literature contains conflicting data with regard to the performance, compositional stability, and chemical reactivity of the Li/Na electrolyte. Experiments conducted at the Institute of Gas Technology (IGT) concluded that the source of the problem is the different wetting characteristics of the two electrolytes. Electrode pore structures optimized for use with Li/K do not work well with Li/Na. Using proprietary methods and materials, IGT was able to optimize a set of electrodes for the Li/Na electrolyte. Experiments conducted in bench-scale cells have confirmed the superior performance of the Li/Na electrolyte compared to the Li/K electrolyte. The Li/Na cells exhibited a 5 to 8 percent improvement in overall performance, a substantial decrease in the rate of cathode dissolution, and a decreased decay rate. The longest running cell has logged over 13,000 hours of operation with a decay rate of less than 2 mV/1000 hours.

  5. Li2OHCl crystalline electrolyte for stable metallic lithium anodes

    DOE PAGES

    Hood, Zachary D.; Wang, Hui; Samuthira Pandian, Amaresh; ...

    2016-01-22

    In a classic example of stability from instability, we show that Li2OHCl solid electrolyte forms a stable solid electrolyte interface (SEI) with metallic lithium anode. The Li2OHCl solid electrolyte can be readily achieved through simple mixing of air-stable LiOH and LiCl precursors with a mild processing temperature under 400 °C. Additionally, we show that continuous, dense Li2OHCl membranes can be fabricated at temperatures less than 400 °C, standing in great contrast to current processing temperatures of over 1600 °C for most oxide-based solid electrolytes. The ionic conductivity and Arrhenius activation energy were explored for the LiOH-LiCl system of crystalline solidmore » electrolytes where Li2OHCl with increased crystal defects was found to have the highest ionic conductivity and reasonable Arrhenius activation energy. The Li2OHCl solid electrolyte displays stability against metallic lithium, even in extreme conditions past the melting point of lithium metal. Furthermore, to understand this excellent stability, we show that SEI formation is critical in stabilizing the interface between metallic lithium and the Li2OHCl solid electrolyte.« less

  6. Elastic Properties of the Solid Electrolyte Li7La3Zr2O12 (LLZO)

    SciTech Connect

    Yu, Seungho; Schmidt, Robert D.; Garcia-mendez, Regina; Herbert, Erik G.; Dudney, Nancy J.; Wolfenstine, Jeff; Sakamoto, Jeff; Seigel, Donald

    2015-12-16

    The oxide known as LLZO, with nominal composition Li7La3Zr2O12, is a promising solid electrolyte for Li-based batteries due to its high Li-ion conductivity and chemical stability with respect to lithium. Solid electrolytes may also enable the use of metallic Li anodes by serving as a physical barrier that suppresses dendrite initiation and propagation during cycling. Prior linear elasticity models of the Li electrode/solid electrolyte interface suggest that the stability of this interface is highly dependent on the elastic properties of the solid separator. For example, dendritic suppression is predicted to be enhanced as the electrolyte s shear modulus increases. In the present study a combination of first-principles calculations, acoustic impulse excitation measurements, and nanoindentation experiments are used to determine the elastic constants and moduli for highconductivity LLZO compositions based on Al and Ta doping. The calculated and measured isotropic shear moduli are in good agreement and fall within the range of 56-61 GPa. These values are an order of magnitude larger than that for Li metal and far exceed the minimum value ( 8.5 GPa) believed to be necessary to suppress dendrite initiation. These data suggest that LLZO exhibits sufficient stiffness to warrant additional development as a solid electrolyte for Li batteries.

  7. Elastic Properties of the Solid Electrolyte Li7La3Zr2O12 (LLZO)

    DOE PAGES

    Yu, Seungho; Schmidt, Robert D.; Garcia-mendez, Regina; ...

    2015-12-16

    The oxide known as LLZO, with nominal composition Li7La3Zr2O12, is a promising solid electrolyte for Li-based batteries due to its high Li-ion conductivity and chemical stability with respect to lithium. Solid electrolytes may also enable the use of metallic Li anodes by serving as a physical barrier that suppresses dendrite initiation and propagation during cycling. Prior linear elasticity models of the Li electrode/solid electrolyte interface suggest that the stability of this interface is highly dependent on the elastic properties of the solid separator. For example, dendritic suppression is predicted to be enhanced as the electrolyte s shear modulus increases. Inmore » the present study a combination of first-principles calculations, acoustic impulse excitation measurements, and nanoindentation experiments are used to determine the elastic constants and moduli for highconductivity LLZO compositions based on Al and Ta doping. The calculated and measured isotropic shear moduli are in good agreement and fall within the range of 56-61 GPa. These values are an order of magnitude larger than that for Li metal and far exceed the minimum value ( 8.5 GPa) believed to be necessary to suppress dendrite initiation. These data suggest that LLZO exhibits sufficient stiffness to warrant additional development as a solid electrolyte for Li batteries.« less

  8. Self-doped molecular composite battery electrolytes

    DOEpatents

    Harrup, Mason K.; Wertsching, Alan K.; Stewart, Frederick F.

    2003-04-08

    This invention is in solid polymer-based electrolytes for battery applications. It uses molecular composite technology, coupled with unique preparation techniques to render a self-doped, stabilized electrolyte material suitable for inclusion in both primary and secondary batteries. In particular, a salt is incorporated in a nano-composite material formed by the in situ catalyzed condensation of a ceramic precursor in the presence of a solvated polymer material, utilizing a condensation agent comprised of at least one cation amenable to SPE applications. As such, the counterion in the condensation agent used in the formation of the molecular composite is already present as the electrolyte matrix develops. This procedure effectively decouples the cation loading levels required for maximum ionic conductivity from electrolyte physical properties associated with condensation agent loading levels by utilizing the inverse relationship discovered between condensation agent loading and the time domain of the aging step.

  9. Computational Exploration of the Li-Electrode|Electrolyte Interface in the Presence of a Nanometer Thick Solid-Electrolyte Interphase Layer.

    PubMed

    Li, Yunsong; Leung, Kevin; Qi, Yue

    2016-10-18

    pathways, we design methods to accelerate the Li(+) ion conductivity by doping and by using heterogonous structure designs. We will predict the electron tunneling barriers and connect them with measurable first cycle irreversible capacity loss. Finally, we note that the SEI not only affects Li(+) and e(-) transport, but it can also impose a potential drop near the Li-metal|SEI interface. Our challenge is to fully describe the electrochemical reactions at the Li-metal|SEI|electrolyte interface. This will be the subject of ongoing efforts.

  10. Polymer electrolytes for a rechargeable li-Ion battery

    SciTech Connect

    Argade, S.D.; Saraswat, A.K.; Rao, B.M.L.; Lee, H.S.; Xiang, C.L.; McBreen, J.

    1996-10-01

    Lithium-ion polymer electrolyte battery technology is attractive for many consumer and military applications. A Li{sub x}C/Li{sub y}Mn{sub 2}O{sub 4} battery system incorporating a polymer electrolyte separator base on novel Li-imide salts is being developed under sponsorship of US Army Research Laboratory (Fort Monmouth NJ). This paper reports on work currently in progress on synthesis of Li-imide salts, polymer electrolyte films incorporating these salts, and development of electrodes and cells. A number of Li salts have been synthesized and characterized. These salts appear to have good voltaic stability. PVDF polymer gel electrolytes based on these salts have exhibited conductivities in the range 10{sup -4} to 10{sub -3} S/cm.

  11. Chemical Passivation of Li(exp +)-Conducting Solid Electrolytes

    NASA Technical Reports Server (NTRS)

    West, William; Whitacre, Jay; Lim, James

    2008-01-01

    Plates of a solid electrolyte that exhibits high conductivity for positive lithium ions can now be passivated to prevent them from reacting with metallic lithium. Such passivation could enable the construction and operation of high-performance, long-life lithium-based rechargeable electrochemical cells containing metallic lithium anodes. The advantage of this approach, in comparison with a possible alternative approach utilizing lithium-ion graphitic anodes, is that metallic lithium anodes could afford significantly greater energy-storage densities. A major impediment to the development of such cells has been the fact that the available solid electrolytes having the requisite high Li(exp +)-ion conductivity are too highly chemically reactive with metallic lithium to be useful, while those solid electrolytes that do not react excessively with metallic lithium have conductivities too low to be useful. The present passivation method exploits the best features of both extremes of the solid-electrolyte spectrum. The basic idea is to coat a higher-conductivity, higher-reactivity solid electrolyte with a lower-conductivity, lower-reactivity solid electrolyte. One can then safely deposit metallic lithium in contact with the lower-reactivity solid electrolyte without incurring the undesired chemical reactions. The thickness of the lower-reactivity electrolyte must be great enough to afford the desired passivation but not so great as to contribute excessively to the electrical resistance of the cell. The feasibility of this method was demonstrated in experiments on plates of a commercial high-performance solid Li(exp +)- conducting electrolyte. Lithium phosphorous oxynitride (LiPON) was the solid electrolyte used for passivation. LiPON-coated solid-electrolyte plates were found to support electrochemical plating and stripping of Li metal. The electrical resistance contributed by the LiPON layers were found to be small relative to overall cell impedances.

  12. Computational Exploration of the Li-Electrode|Electrolyte Interface in the Presence of a Nanometer Thick Solid-Electrolyte Interphase Layer [Computational exploration of the Li-electrode|electrolyte interface complicated by a nanometer thin solid-electrolyte interphase (SEI) layer

    SciTech Connect

    Li, Yunsong; Leung, Kevin; Qi, Yue

    2016-09-30

    2O, and their mixtures. After sorting out the Li+ ion diffusion carriers and their diffusion pathways, we design methods to accelerate the Li+ ion conductivity by doping and by using heterogonous structure designs. We will predict the electron tunneling barriers and connect them with measurable first cycle irreversible capacity loss. We note that the SEI not only affects Li+ and e transport, but it can also impose a potential drop near the Li-metal|SEI interface. Our challenge is to fully describe the electrochemical reactions at the Li-metal|SEI|electrolyte interface. This will be the subject of ongoing efforts.

  13. Computational Exploration of the Li-Electrode|Electrolyte Interface in the Presence of a Nanometer Thick Solid-Electrolyte Interphase Layer [Computational exploration of the Li-electrode|electrolyte interface complicated by a nanometer thin solid-electrolyte interphase (SEI) layer

    DOE PAGES

    Li, Yunsong; Leung, Kevin; Qi, Yue

    2016-09-30

    their diffusion pathways, we design methods to accelerate the Li+ ion conductivity by doping and by using heterogonous structure designs. We will predict the electron tunneling barriers and connect them with measurable first cycle irreversible capacity loss. We note that the SEI not only affects Li+ and e– transport, but it can also impose a potential drop near the Li-metal|SEI interface. Our challenge is to fully describe the electrochemical reactions at the Li-metal|SEI|electrolyte interface. This will be the subject of ongoing efforts.« less

  14. Acid and alkali doped PBI electrolyte in electrochemical system

    NASA Astrophysics Data System (ADS)

    Xing, Baozhong

    In this work the conductivity of blank PBI membrane, acid doped PBI and alkaline doped PBI was systematically studied. A new methodology for sorption kinetics study in electrolyte solution has been established by monitoring the conductivity change during the sorption process. The model of the doping process and mechanism of conductivity are proposed. The performance of PBI (doped under optimum conditions) in fuel cell as PEM was evaluated. The experimental results show that the blank PBI in acid solution is an ionic insulator. It clarified the long time confusion in this area. The acid doped PBI membrane is an ionic conductor. The conductivity increases with the concentration of the acid solution. In high concentration acid solution, the conductivity increases with the type of acid in the order: H2SO 4 > H3PO4 > HClO4 > HNO3 > HCl. The kinetics of the doping process was studied, by a continuous method. The ionic conductivity mechanism was established. The PBI membranes doped with H2SO4 and H3PO4 exhibit better performance than NafionRTM. The doped FBI has more resistance to CO poison. 3% CO in H2 has little effect on the H3PO 4 doped PBI membrane at 185°C. The conductivity of the alkali doped PBI membrane changes with the concentration of the alkaline solution and the type of the alkalis. The conductivity has a maximum in KOH and NaOH solution. The maximum conductivity in KOH is higher than in NaOH and LiOH. It is about 5 times of that of NafionRTM in alkaline solution. The two-step sorption process in alkaline solution was observed. The first step is the permeation process of the alkalis in the PBI membrane. The permeation is the results of diffusion and interaction. It is concluded that the permeation process is controlled by the rate of interaction between the alkali and PBI molecule. The second step is the relaxation process in the membrane. This step contributes more to the conductivity for the membrane than the first step. The ionic conductivity mechanism

  15. Modification of LiCl-LiBr-KBr electrolyte for LiAl/FeS{sub 2} batteries

    SciTech Connect

    Kaun, T.D.; Jansen, A.N.; Henriksen, G.L.; Vissers, D.R.

    1996-06-01

    The bipolar LiAl/FeS{sub 2} battery is being developed to achieve the high performance and long cycle life needed for electric vehicle application. The molten-salt (400 to 440 C operation) electrolyte composition for this battery has evolved to support these objectives. An earlier change to LiCl-LiBr-KBr electrolyte is responsible for significantly increased cycle life (up to 1,000 cycles). Recent electrolyte modification has significantly improved cell performance; approximately 50% increased power, with increased high rate capacity utilization. Results are based on power-demanding EV driving profile test at 600 W/kg. The effects of adding small amounts (1--5 mol%) of LiF and LiI to LiCl-LiBr-KBr electrolyte are discussed. By cyclic voltammetry, the modified electrolytes exhibit improved FeS{sub 2} electrochemistry. Electrolyte conductivity is little changed, but high current density (200 mA/cm{sup 2}) performance improved by approximately 50%. A specific feature of the LiI addition is an enhanced cell overcharge tolerance rate from 2.5 to 5 mA/cm{sup 2}. The rate of overcharge tolerance is related to electrolyte properties and negative electrode lithium activity. As a result, the charge balancing of a bipolar battery configuration with molten-salt electrolyte is improved to accept greater cell-to-cell deviations.

  16. Developing New Electrolytes for Advanced Li-ion Batteries

    NASA Astrophysics Data System (ADS)

    McOwen, Dennis Wayne

    The use of renewable energy sources is on the rise, as new energy generating technologies continue to become more efficient and economical. Furthermore, the advantages of an energy infrastructure which relies more on sustainable and renewable energy sources are becoming increasingly apparent. The most readily available of these renewable energy sources, wind and solar energy in particular, are naturally intermittent. Thus, to enable the continued expansion and widespread adoption of renewable energy generating technology, a cost-effective energy storage system is essential. Additionally, the market for electric/hybrid electric vehicles, which both require efficient energy storage, continues to grow as more consumers seek to reduce their consumption of gasoline. These vehicles, however, remain quite expensive, due primarily to costs associated with storing the electrical energy. High-voltage and thermally stable Li-ion battery technology is a promising solution for both grid-level and electric vehicle energy storage. Current limitations in materials, however, limit the energy density and safe operating temperature window of the battery. Specifically, the state-of-the-art electrolyte used in Li-ion batteries is not compatible with recently developed high-voltage positive electrodes, which are one of the most effectual ways of increasing the energy density. The electrolyte is also thermally unstable above 50 °C, and prone to thermal runaway reaction if exposed to prolonged heating. The lithium salt used in such electrolytes, LiPF6, is a primary contributor to both of these issues. Unfortunately, an improved lithium salt which meets the myriad property requirements for Li-ion battery electrolytes has eluded researchers for decades. In this study, a renewed effort to find such a lithium salt was begun, using a recently developed methodology to rapidly screen for desirable properties. Four new lithium salts and one relatively new but uncharacterized lithium salt were

  17. Electrolytes in Support of 5V Li-ion Batteries

    DTIC Science & Technology

    2010-12-16

    candidates LiCoPO4, LiNi0.5Mn1.5O4, Li2FeCoPO4 etc, projected to deliver 15~40% more energy than state-of-art LiFePO4 The additive invented by SEDD is...battery pack for HEV as example: 300 V hybrid electric system • requires at least 100 LiFePO4 Li ion cells in series • power electronics, protection...FOR PUBLIC RELEASE The “5V” Li ion cathode needs a “5V” electrolyte • Potentially up to 40% greater energy density than LiFePO4 • Higher voltage at

  18. Passivation of Lithium Metal Anode via Hybrid Ionic Liquid Electrolyte toward Stable Li Plating/Stripping.

    PubMed

    Li, Nian-Wu; Yin, Ya-Xia; Li, Jin-Yi; Zhang, Chang-Huan; Guo, Yu-Guo

    2017-02-01

    Hybrid electrolyte of ionic liquid and ethers is used to passivate the surface of Li metal surface via modification of the as-formed solid electrolyte interphase with N-propyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide (Py13TFSI), thereby reducing the side reactions between the Li metal and electrolyte, leading to remarkably suppressed Li dendrite growth and mitigating Li metal corrosion.

  19. Photocured Gelled Electrolytes For Secondary Li Cells

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, Ganesan

    1994-01-01

    Class of photocured polymers exhibiting lithium-ion conductivities greater than those of well-studied polymers based on polyethylene oxide (PEO) show promise as polymeric electrolytes in rechargeable lithium cells. Increase in conductivity occasioned by use of electrolytes, coupled with amenability of electrolytes to formation into uniform thin (less than 25 micrometers thick), wide films, expected to result in cells with power densities greater than 100 W h/kg and charge/discharge rates exceeding currents equal, in amperes, to ampere-hour ratings. All-solid-state lithium batteries containing these electrolytes used as high-power, high-rate rechargeable power sources in commercial and aerospace applications.

  20. Electrolytic LiCl precipitation from LiCl-KCl melt in porous Li-Al anodes

    SciTech Connect

    Vallet, C.E.; Heatherly, D.E.; Heatherly, L. Jr.; Braunstein, J.

    1983-12-01

    Composition gradients such as those predicted to occur during discharge of porous Li-Al negative electrodes of Li/S batteries with LiCl-KCl eutectic electrolyte were generated and measured in the LiCl-KCl anolyte of an electrolysis cell with Li-Al electrodes. Precipitation of lithium chloride during electrolysis was observed by two-dimensional scanning of electrolyte composition in the front part of quenched porous Li-Al anode sections using SEM/EDX. The distribution of sites of increased or decreased LiCl concentration, LiCl saturation and precipitation was mapped. Cathodic regions were observed near the cell walls. Preliminary results of analysis by Auger spectroscopy confirm LiCl precipitation in the porous anode. 16 references, 7 figures, 1 table.

  1. Electrolytic LiCl precipitation from LiCl-KCl melt in porous Li-Al anodes

    NASA Astrophysics Data System (ADS)

    Vallet, C. E.; Heatherly, D. E.; Heatherly, L., Jr.; Braunstein, J.

    1983-12-01

    Composition gradients such as those predicted to occur during discharge of porous Li-Al negative electrodes of Li/S batteries with LiCl-KCl eutectic electrolyte were generated and measured in the LiCl-KCl anolyte of an electrolysis cell with Li-Al electrodes. Precipitation of lithium chloride during electrolysis was observed by two-dimensional scanning of electrolyte composition in the front part of quenched porous Li-Al anode sections using SEM/EDX. The distribution of sites of increased or decreased LiCl concentration, LiCl saturation and precipitation was mapped. Cathodic regions were observed near the cell walls. Preliminary results of analysis by Auger spectroscopy confirm LiCl precipitation in the porous anode.

  2. LiGa(OTf)(sub 4) as an Electrolyte Salt for Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Reddy, V. Prakash; Prakash, G. K. Syria; Hu, Jinbo; Yan, Ping; Smart, Marshall; Bugga, ratnakumar; Chin, Keith; Surampudi, Subarao

    2008-01-01

    Lithium tetrakis(trifluoromethane sulfo - nato)gallate [abbreviated "LiGa(OTf)4" (wherein "OTf" signifies trifluoro - methanesulfonate)] has been found to be promising as an electrolyte salt for incorporation into both liquid and polymer electrolytes in both rechargeable and non-rechargeable lithium-ion electrochemical cells. This and other ingredients have been investigated in continuing research oriented toward im proving the performances of rechargeable lithium-ion electrochemical cells, especially at low temperatures. This research at earlier stages, and the underlying physical and chemical principles, were reported in numerous previous NASA Tech Briefs articles. As described in more detail in those articles, lithiumion cells most commonly contain nonaqueous electrolyte solutions consisting of lithium hexafluorophosphate (LiPF6) dissolved in mixtures of cyclic and linear alkyl carbonates, including ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). Although such LiPF6-based electrolyte solutions are generally highly ionically conductive and electrochemically stable, as needed for good cell performance, there is interest in identifying alternate lithium electrolyte salts that, relative to LiPF6, are more resilient at high temperature and are less expensive. Experiments have been performed on LiGa(OTf)4 as well as on several other candidate lithium salts in pursuit of this interest. As part of these experiments, LiGa(OTf)4 was synthesized by the reaction of Ga(OTf)3 with an equimolar portion of LiOTf in a solvent consisting of anhydrous acetonitrile. Evaporation of the solvent yielded LiGa(OTf)4 as a colorless crystalline solid. The LiGa(OTf)4 and the other salts were incorporated into solutions with PC and DMC. The resulting electrolyte solutions exhibited reasonably high ionic conductivities over a relatively wide temperature range down to 40 C (see figure). In cyclic

  3. Electrolytes for Li-Ion Cells in Low Temperature Applications

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Surampudi, S.

    2000-01-01

    Prototype AA-size lithium-ion cells have been demonstrated to operate effectively at temperatures as low as -30 to -40 C. These improvements in low temperature cell performance have been realized by the incorporation of ethylene carbonate-based electrolytes which possess low melting, low viscosity cosolvents, such as methyl acetate, ethyl acetate, gamma-butyrolactone, and ethyl methyl carbonate. The cells containing a 0.75M LiPF6 EC+DEC+DMC+EMC (1:1:1:1) electrolyte displayed the best performance at -30 C (> 90% of the room temperature capacity at approximately C/15 rate), whereas, at -40 C the cells with the 0.75M LiPF6 EC+DEC+DMC+MA (1:1:1:1) and 0.75M LiPF6 EC+DEC+DMC+EA (1:1:1:1) electrolytes showed superior performance.

  4. Film formation in LiBOB-containing electrolytes

    NASA Astrophysics Data System (ADS)

    Panitz, Jan-Christoph; Wietelmann, Ulrich; Wachtler, Mario; Ströbele, Sandra; Wohlfahrt-Mehrens, Margret

    Lithium bis(oxalato)borate (LiBOB), a new electrolyte salt for lithium batteries, is actively involved in the formation of the solid electrolyte interphase (SEI) at the anode. Part of this formation is an irreversible reductive reaction taking place at potentials of around 1.75 V versus Li/Li + and contributing to the irreversible capacity of anode materials in the first cycle. Cyclic voltammetry has been performed on several carbon materials as well as on Li 4Ti 5O 12 and pre-treated glassy carbon electrodes in order to achieve a better understanding of the underlying processes. It is found that the intensity of the 1.75 V peak depends on the BET specific surface area and the surface chemistry of the active material and increases with the amount of oxygen-containing surface functionalities. It is not specific to carbonaceous materials but is also observed on carbon-free anodes like Li 4Ti 5O 12. In addition, the effect of several potential impurities and of film-forming additives on the filming behaviour of LiBOB-containing electrolytes has been investigated.

  5. Conductivity and properties of polysiloxane-polyether cluster-LiTFSI networks as hybrid polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Boaretto, Nicola; Joost, Christine; Seyfried, Mona; Vezzù, Keti; Di Noto, Vito

    2016-09-01

    This report describes the synthesis and the properties of a series of polymer electrolytes, composed of a hybrid inorganic-organic matrix doped with LiTFSI. The matrix is based on ring-like oligo-siloxane clusters, bearing pendant, partially cross-linked, polyether chains. The dependency of the thermo-mechanic and of the transport properties on several structural parameters, such as polyether chains' length, cross-linkers' concentration, and salt concentration is studied. Altogether, the materials show good thermo-mechanical and electrochemical stabilities, with conductivities reaching, at best, 8·10-5 S cm-1 at 30 °C. In conclusion, the cell performances of one representative sample are shown. The scope of this report is to analyze the correlations between structure and properties in networked and hybrid polymer electrolytes. This could help the design of optimized polymer electrolytes for application in lithium metal batteries.

  6. On the structural and impedance characteristics of Li- doped PEO, using n-butyl lithium in hexane as dopant

    SciTech Connect

    Anand, P. B. E-mail: jayalekshmi@cusat.ac.in; Jayalekshmi, S. E-mail: jayalekshmi@cusat.ac.in

    2014-01-28

    Nowadays polymer based solid state electrolytes for applications in rechargeable battery systems are highly sought after materials, pursued extensively by various research groups worldwide. Numerous methods are discussed in literature to improve the fundamental properties like electrical conductivity, mechanical stability and interfacial stability of polymer based electrolytes. The application of these electrolytes in Li-ion cells is still in the amateur state, due to low ionic conductivity, low lithium transport number and the processing difficulties. The present work is an attempt to study the effects of Li doping on the structural and transport properties of the polymer electrolyte, poly-ethelene oxide (PEO) (Molecular weight: 200,000). Li doped PEO was obtained by treating PEO with n-Butyllithium in hexane for different doping concentrations. Structural characterization of the samples was done by XRD and FTIR techniques. Impedance measurements were carried out to estimate the ionic conductivity of Li doped PEO samples. It is seen that, the crystallinity of the doped PEO decreases on increasing the doping concentration. XRD and FTIR studies support this observation. It is inferred that, ionic conductivity of the sample is increasing on increasing the doping concentration since less crystallinity permits more ionic transport. Impedance measurements confirm the results quantitatively.

  7. Stability of the Solid Electrolyte Interface on the Li Electrode in Li–S Batteries

    SciTech Connect

    Zheng, Dong; Yang, Xiao-Qing; Qu, Deyang

    2016-04-05

    In this study, by means of high performance liquid chromatography–mass spectroscopy, the concentration of sulfur and polysulfides was determined in nonaqueous electrolytes. The stability of sulfur and Li in eight electrolytes was studied quantitatively. It was found that sulfur reacted with Li in most of the commonly used electrolytes for lithium–sulfur batteries. The reaction products between sulfur and Li were qualitatively identified. In some cases, the solid electrolyte interface on the Li can successfully prevent the interaction between S and Li; however, it was found that the solid electrolyte interface was damaged by polysulfide ions.

  8. A molecular dynamics simulation study of LiFePO4/electrolyte interfaces: structure and Li+ transport in carbonate and ionic liquid electrolytes.

    PubMed

    Smith, Grant D; Borodin, Oleg; Russo, Salvy P; Rees, Robert J; Hollenkamp, Anthony F

    2009-11-14

    We have performed atomistic molecular dynamics (MD) simulations of the (010) surface of LiFePO(4) in contact with an organic liquid electrolyte (OLE), ethylene carbonate : dimethyl carbonate (3 : 7) with approximately 1 mol kg(-1) LiPF(6), and an ionic liquid-based electrolyte (ILE), 1-ethyl 3-methyl-imidazolium: bis(fluorosulfonyl)imide (EMIM(+) : FSI(-)) with approximately 1 mol kg(-1) LiFSI. Surface-induced structure that extends about 1 nm from the LiFePO(4) surface was observed in both electrolytes. The electrostatic potential at the LiFePO(4) surface was found to be negative relative to the bulk electrolyte reflecting an excess of negative charge from the electrolyte coordinating surface Li(+). In the ILE system negative surface charge is partially offset by a high density of EMIM(+) cations coordinating surface oxygen. The electrostatic potential exhibits a (positive) maximum about 3 A from the LiFePO(4) surface which, when combined with the reduced ability of the highly structured electrolytes to solvate Li(+) cations, results in a free energy barrier of almost 4 kcal mol(-1) for penetration of the interfacial electrolyte layer by Li(+). The resistance for bringing Li(+) from the bulk electrolyte to the LiFePO(4) surface through this interfacial barrier was found to be small for both the OLE and ILE. However, we find that the ability of EMIM(+) cations to donate positive charge to LiFePO(4)/electrolyte interface may result in a significant decrease in the concentration of Li(+) at the surface and a corresponding increase in impedance to Li(+) intercalation into LiFePO(4), particularly at lower temperatures.

  9. Simulated electrolyte-metal interfaces -- Li3PO4 and Li

    NASA Astrophysics Data System (ADS)

    Xu, Xiao; Du, Yaojun A.; Holzwarth, N. A. W.

    2007-03-01

    There has recently been a lot of interest in solid electrolyte materials such as LiPON developed at Oak Ridge National Laboratory for use in Li-ion batteries and other technologies. We report on the results of our model calculations on idealized interfaces between Li3PO4 and Li metal, studying the structural stability and the ion mobility, using first-principles density functional techniques with the PWscf and pwpaw codes. Starting with a supercell constructed from Li3PO4 in its crystalline γ-phase structure and several layers of Li metal, we used optimization and molecular dynamics techniques to find several meta-stable configurations. The qualitative features of the results are consistent with experimental evidence that the electrolyte is quite stable with respect to Li metal. In addition to stability analyses, we plan to study Li-ion diffusion across the interface. J. B. Bates, N. J. Dudney, and co-workers, Solid State Ionics, 53-56, 647-654 (1992). http://www.pwscf.org and http://pwpaw.wfu.edu. N. J. Dudney in Gholam-Abbas Nazri and Gianfranco Pistoia, Eds., Lithium Batteries: Science and Technology, Chapt. 20, pp. 623-642, Kluwer Academic Publishers, 2004. ISBN 1-4020-7628-2.

  10. Effect of a pyrrolidinium zwitterion on charge/discharge cycle properties of Li/LiCoO2 and graphite/Li cells containing an ionic liquid electrolyte

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Seitaro; Yoshizawa-Fujita, Masahiro; Takeoka, Yuko; Rikukawa, Masahiro

    2016-11-01

    Ionic liquids (ILs) containing zwitterions have been studied as electrolytes for lithium-ion batteries (LIBs). The effects of addition of a pyrrolidinium zwitterion in an IL electrolyte on the thermal and electrochemical stability and charge/discharge properties of Li/LiCoO2 and graphite/Li cells were investigated. The thermal decomposition temperature of the IL electrolyte composed of N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)amide ([P13][FSA])/lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) with 3-(1-butylpyrrolidinium)propane-1-sulfonate (Bpyps) as the zwitterionic additive, the thermal decomposition temperature was about 300 °C. The electrochemical window of [P13][FSA]/LiTFSA/Bpyps was 0-+5.4 V vs. Li/Li+, which was almost identical to that of [P13][FSA]/LiTFSA. Li|electrolyte|LiCoO2 cells containing the IL/Bpyps electrolyte system exhibited high capacities in the cut-off voltage range of 3.0-4.6 V, even after 50 cycles. The increase in the interfacial resistance between the electrolyte and cathode with cycling was suppressed. In the cyclic voltammograms of cells employing a graphite electrode, the intercalation/deintercalation of lithium ions were observed in the range of 0 and + 0.4 V vs. Li/Li+. Further, graphite|electrolyte|Li cells containing [P13][FSA]/LiTFSA/Bpyps exhibited stable charge/discharge cycle behaviour over 50 cycles.

  11. Optimized Carbonate and Ester-Based Li-Ion Electrolytes

    NASA Technical Reports Server (NTRS)

    Smart, Marshall; Bugga, Ratnakumar

    2008-01-01

    To maintain high conductivity in low temperatures, electrolyte co-solvents have been designed to have a high dielectric constant, low viscosity, adequate coordination behavior, and appropriate liquid ranges and salt solubilities. Electrolytes that contain ester-based co-solvents in large proportion (greater than 50 percent) and ethylene carbonate (EC) in small proportion (less than 20 percent) improve low-temperature performance in MCMB carbon-LiNiCoO2 lithium-ion cells. These co-solvents have been demonstrated to enhance performance, especially at temperatures down to 70 C. Low-viscosity, ester-based co-solvents were incorporated into multi-component electrolytes of the following composition: 1.0 M LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + X (1:1:8 volume percent) [where X = methyl butyrate (MB), ethyl butyrate EB, methyl propionate (MP), or ethyl valerate (EV)]. These electrolyte formulations result in improved low-temperature performance of lithium-ion cells, with dramatic results at temperatures below 40 C.

  12. Enhancing the Li storage capacity and initial coulombic efficiency for porous carbons by sulfur doping.

    PubMed

    Ning, Guoqing; Ma, Xinlong; Zhu, Xiao; Cao, Yanming; Sun, Yuzhen; Qi, Chuanlei; Fan, Zhuangjun; Li, Yongfeng; Zhang, Xin; Lan, Xingying; Gao, Jinsen

    2014-09-24

    Here, we report a new approach to synthesizing S-doped porous carbons and achieving both a high capacity and a high Coulombic efficiency in the first cycle for carbon nanostructures as anodes for Li ion batteries. S-doped porous carbons (S-PCs) were synthesized by carbonization of pitch using magnesium sulfate whiskers as both templates and S source, and a S doping up to 10.1 atom % (corresponding to 22.5 wt %) was obtained via a S doping reaction. Removal of functional groups or highly active C atoms during the S doping has led to formation of much thinner solid-electrolyte interface layer and hence significantly enhanced the Coulombic efficiency in the first cycle from 39.6% (for the undoped porous carbon) to 81.0%. The Li storage capacity of the S-PCs is up to 1781 mA h g(-1) at the current density of 50 mA g(-1), more than doubling that of the undoped porous carbon. Due to the enhanced conductivity, the hierarchically porous structure and the excellent stability, the S-PC anodes exhibit excellent rate capability and reliable cycling stability. Our results indicate that S doping can efficiently promote the Li storage capacity and reduce the irreversible Li combination for carbon nanostructures.

  13. Effects of electrolyte salts on the performance of Li-O2 batteries

    SciTech Connect

    Nasybulin, Eduard N.; Xu, Wu; Engelhard, Mark H.; Nie, Zimin; Burton, Sarah D.; Cosimbescu, Lelia; Gross, Mark E.; Zhang, Jiguang

    2013-02-05

    It is well known that the stability of nonaqueous electrolyte is critical for the rechargeable Li-O2 batteries. Although stability of many solvents used in the electrolytes has been investigated, considerably less attention has been paid to the stability of electrolyte salt which is the second major component. Herein, we report the systematic investigation of the stability of seven common lithium salts in tetraglyme used as electrolytes for Li-O2 batteries. The discharge products of Li-O2 reaction were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy and nuclear magnetic resonance spectroscopy. The performance of Li-O2 batteries was strongly affected by the salt used in the electrolyte. Lithium tetrafluoroborate (LiBF4) and lithium bis(oxalato)borate (LiBOB) decompose and form LiF and lithium borates, respectively during the discharge of Li-O2 batteries. Several other salts, including lithium bis(trifluoromethane)sulfonamide (LiTFSI), lithium trifluoromethanesulfonate (LiTf), lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4) , and lithium bromide (LiBr) led to the discharge products which mainly consisted of Li2O2 and only minor signs of decomposition of LiTFSI, LiTf, LPF6 and LiClO4 were detected. LiBr showed the best stability during the discharge process. As for the cycling performance, LiTf and LiTFSI were the best among the studied salts. In addition to the instability of lithium salts, decomposition of tetraglyme solvent was a more significant factor contributing to the limited cycling stability. Thus a more stable nonaqueous electrolyte including organic solvent and lithium salt still need to be further developed to reach a fully reversible Li-O2 battery.

  14. Unusual Li-Ion Transfer Mechanism in Liquid Electrolytes: A First-Principles Study.

    PubMed

    Tang, Zhen-Kun; Tse, John S; Liu, Li-Min

    2016-11-17

    Liquid electrolytes play an important role in commercial lithium-ion (Li-ion) batteries as a conduit for Li-ion transfer between anodes and cathodes. It is generally believed that the Li-ions move along with the salt ions; thus, Li-ion diffusion is only affected by the viscosity and salt concentration in the liquid electrolytes based on the Stokes-Einstein equation. In this study, a novel and faster Li-ion diffusion mechanism in electrolytes containing a cyanogen group is identified from first-principles molecular dynamics (FPMD) simulations. In this mechanism, the Li-ions are first detached from the Li-salt and then diffuse along with the solvent molecules, and the Li-ion diffusion does not obey the traditional Stokes-Einstein equation. The ionic conductivity of the electrolyte systems with this "solvent-assisted Li-ion diffusion" mechanism is further enhanced through Li-ion hopping. This novel Li-ion diffusion process explains recent findings of high Li-ion conductivity in electrolytes with cyanogen groups and furnishes a new paradigm for the design of fast-charging liquid electrolyte for Li-ion batteries.

  15. Composite polymer electrolyte for Li-ion battery

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Xu, Fan; Cheng, Yan; Jiang, Zhiyu

    2002-06-01

    A new method presented in this work mainly describes how to produce polymer electrolyte membranes by using water as plasticizer. Compared with the membranes made by traditional methods, the membranes made by the new method have the properties of easy handling and free-standing. The results of Ac impedance suggest that the polymer electrolyte membranes have high ionic conductivity. Moreover, the images of SEM show that the porous and alveolate structures are greatly improved. It is more important that using water as plasticizer can lower the cost of producing Li-ion batteries and eliminate the pollution produced in process of plasticizer extraction, in which some volatile solvents were used in traditional methods.

  16. Method for treating electrolyte to remove Li.sub.2 O

    DOEpatents

    Tomczuk, Zygmunt; Miller, William E.; Johnson, Gerald K.; Willit, James L.

    1998-01-01

    A method of removing Li.sub.2 O present in an electrolyte predominantly of LiCl and KCl. The electrolyte is heated to a temperature not less than about 500.degree. C. and then Al is introduced into the electrolyte in an amount in excess of the stoichiometric amount needed to convert the Li.sub.2 O to a Li-Al alloy and lithium aluminate salt. The salt and aluminum are maintained in contact with agitation for a time sufficient to convert the Li.sub.2 O.

  17. Method for treating electrolyte to remove Li{sub 2}O

    DOEpatents

    Tomczuk, Z.; Miller, W.E.; Johnson, G.K.; Willit, J.L.

    1998-01-20

    A method is described for removing Li{sub 2}O present in an electrolyte predominantly of LiCl and KCl. The electrolyte is heated to a temperature not less than about 500 C and then Al is introduced into the electrolyte in an amount in excess of the stoichiometric amount needed to convert the Li{sub 2}O to a Li-Al alloy and lithium aluminate salt. The salt and aluminum are maintained in contact with agitation for a time sufficient to convert the Li{sub 2}O.

  18. Improved electrolytes for Li-ion batteries: Mixtures of ionic liquid and organic electrolyte with enhanced safety and electrochemical performance

    NASA Astrophysics Data System (ADS)

    Guerfi, A.; Dontigny, M.; Charest, P.; Petitclerc, M.; Lagacé, M.; Vijh, A.; Zaghib, K.

    Physical and electrochemical characteristics of Li-ion battery systems based on LiFePO 4 cathodes and graphite anodes with mixture electrolytes were investigated. The mixed electrolytes are based on an ionic liquid (IL), and organic solvents used in commercial batteries. We investigated a range of compositions to determine an optimum conductivity and non-flammability of the mixed electrolyte. This led us to examine mixtures of ILs with the organic electrolyte usually employed in commercial Li-ion batteries, i.e., ethylene carbonate (EC) and diethylene carbonate (DEC). The IL electrolyte consisted of (trifluoromethyl sulfonylimide) (TFSI) as anion and 1-ethyl-3-methyleimidazolium (EMI) as the cation. The physical and electrochemical properties of some of these mixtures showed an improvement characteristics compared to the constituents alone. The safety was improved with electrolyte mixtures; when IL content in the mixture is ≥40%, no flammability is observed. A stable SEI layer was obtained on the MCMB graphite anode in these mixed electrolytes, which is not obtained with IL containing the TFSI-anion. The high-rate capability of LiFePO 4 is similar in the organic electrolyte and the mixture with a composition of 1:1. The interface resistance of the LiFePO 4 cathode is stabilized when the IL is added to the electrolyte. A reversible capacity of 155 mAh g -1 at C/12 is obtained with cells having at least some organic electrolyte compared to only 124 mAh g -1 with pure IL. With increasing discharge rate, the capacity is maintained close to that in the organic solvent up to 2 C rate. At higher rates, the results with mixture electrolytes start to deviate from the pure organic electrolyte cell. The evaluation of the Li-ion cells; LiFePO 4//Li 4Ti 5O 12 with organic and, 40% mixture electrolytes showed good 1st CE at 98.7 and 93.0%, respectively. The power performance of both cell configurations is comparable up to 2 C rate. This study indicates that safety and

  19. Li2OHCl crystalline electrolyte for stable metallic lithium anodes

    SciTech Connect

    Hood, Zachary D.; Wang, Hui; Samuthira Pandian, Amaresh; Keum, Jong Kahk; Liang, Chengdu

    2016-01-22

    In a classic example of stability from instability, we show that Li2OHCl solid electrolyte forms a stable solid electrolyte interface (SEI) with metallic lithium anode. The Li2OHCl solid electrolyte can be readily achieved through simple mixing of air-stable LiOH and LiCl precursors with a mild processing temperature under 400 °C. Additionally, we show that continuous, dense Li2OHCl membranes can be fabricated at temperatures less than 400 °C, standing in great contrast to current processing temperatures of over 1600 °C for most oxide-based solid electrolytes. The ionic conductivity and Arrhenius activation energy were explored for the LiOH-LiCl system of crystalline solid electrolytes where Li2OHCl with increased crystal defects was found to have the highest ionic conductivity and reasonable Arrhenius activation energy. The Li2OHCl solid electrolyte displays stability against metallic lithium, even in extreme conditions past the melting point of lithium metal. Furthermore, to understand this excellent stability, we show that SEI formation is critical in stabilizing the interface between metallic lithium and the Li2OHCl solid electrolyte.

  20. Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends

    PubMed Central

    Ye, Hui; Huang, Jian; Xu, Jun John; Khalfan, Amish; Greenbaum, Steve G.

    2009-01-01

    Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P13TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P13TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more “conventional” rechargeable lithium and lithium ion batteries. PMID:20354587

  1. Physical properties of Li ion conducting polyphosphazene based polymer electrolytes

    SciTech Connect

    Sanderson, S.; Zawodzinski, T.; Hermes, R.; Davey, J.; Dai, Hongli

    1996-12-31

    We report a systematic study of the transport properties and the underlying physical chemistry of some polyphosphazene (PPhz)-based polymer electrolytes. We synthesized MEEP and variants which employed mixed combinations of different length oxyethylene side-chains. We compare the conductivity and ion-ion interactions in polymer electrolytes obtained with lithium triflate and lithium bis(trifluoromethanesulfonyl)imide (TFSI) salts added to the polymer. The combination of the lithium imide salt and MEEP yields a maximum conductivity of 8 x 10{sup -5} {Omega}{sup -1} cm{sup -1} at room temperature at a salt loading of 8 monomers per lithium. In one of the mixed side-chain variations, a maximum conductivity of 2 x 10{sup -4} {Omega}{sup -1} cm{sup -1} was measured at the same molar ratio. Raman spectral analysis shows some ion aggregation and some polymer - ion interactions in the PPhz-LiTFSI case but much less than observed with Li CF{sub 3}SO{sub 3}. A sharp increase in the Tg as salt is added corresponds to concentrations above which the conductivity significantly decreases and ion associations appear.

  2. Interfacial stability and electrochemical behavior of Li/LiFePO4 batteries using novel soft and weakly adhesive photo-ionogel electrolytes

    NASA Astrophysics Data System (ADS)

    Aidoud, D.; Etiemble, A.; Guy-Bouyssou, D.; Maire, E.; Le Bideau, J.; Guyomard, D.; Lestriez, B.

    2016-10-01

    We have developed flexible polymer-gel electrolytes based on a polyacrylate cross-linked matrix that confines an ionic liquid doped with a lithium salt. Free-standing solid electrolyte membrane is obtained after UV photo-polymerization of acrylic monomers dissolved inside the ionic liquid/lithium salt mixture. The liquid precursor of the photo-ionogel may also be directly deposited onto porous composite electrode, which results in all-solid state electrode/electrolyte stacking after UV illumination. Minor variations in the polymer component of the electrolyte formulation significantly affect the electrochemical behavior in LiFePO4/lithium and lithium/lithium cells. The rate performance increases with an increase of the ionic conductivity, which decreases with the polymer content and decreases with increasing oxygen content in the polyacrylate matrix. Their fairly low modulus endow them weak and beneficial pressure-sensitive-adhesive character. X-Rays Tomography shows that the solid-state photo-ionogel electrolytes keep their integrity upon cycling and that their surface remains smooth. The coulombic efficiency of LiFePO4/lithium cells increases with an increase of the adhesive strength of the photo-ionogel, suggesting a relationship between the contact intimacy at the lithium/photo-ionogel interface and the efficiency of the lithium striping/plating. In lithium/lithium cells, only the photo-ionogels with the higher adhesion strength are able to allow the reversible striping/plating of lithium.

  3. Comparative study of EC/DMC LiTFSI and LiPF 6 electrolytes for electrochemical storage

    NASA Astrophysics Data System (ADS)

    Dahbi, Mouad; Ghamouss, Fouad; Tran-Van, François; Lemordant, Daniel; Anouti, Mérièm

    Lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) salt are potentially a good alternative to LiPF 6 since it could both improve the chemical and thermal stability as salt for electrolyte. This work presents a systematic comparative study between LiPF 6 and LiTFSI in a mixture of EC/DMC on the basis of some of their physicochemical properties. Transport properties (viscosity and conductivity) are compared at various temperatures from -20 to 80 °C. Using Walden rule, we have demonstrated that LiTFSI 1 M in EC/DMC is more ionic than LiPF 6 1 M in the same binary solvent. Moreover, the electrochemical storage properties of an activated carbon electrode were investigated in EC/DMC mixture containing LiTFSI or LiPF 6. The specific capacitance C s of activated carbon was determined from the Galvanostatic charge-discharge curve between 2 and 3.7 V, at low current densities. The capacitance values were found to be 100 and 90 F g -1 respectively for LiTFSI and LiPF 6 electrolytes at 2 mA g -1. On the basis of the physicochemical and electrochemical measurements, we have correlated the improvement of the specific capacitance with activated carbon to the increase of the ionicity of the LiTFSI salt in EC/DMC binary system. The drawback concerning the corrosion of aluminium collectors was resolved by adding a few percentage of LiPF 6 (1%) in the binary electrolyte. Finally, we have studied the electrochemical behavior of intercalation-deintercalation of lithium in the graphite electrode with EC/DMC + LiTFSI as electrolyte. Results of this study indicate that the realization of asymmetric graphite/activated carbon supercapacitors with LiFTSI based electrolyte is possible.

  4. Design and synthesis of a crystalline LiPON electrolyte

    NASA Astrophysics Data System (ADS)

    Holzwarth, N. A. W.; Senevirathne, Keerthi; Day, Cynthia S.; Lachgar, Abdessadek; Gross, Michael D.

    2013-03-01

    In the course of a computation study of the broad class of lithium phosphorus oxy-nitride materials of interest for solid electrolyte applications, Du and Holzwarth, [2] recently predicted a stable crystalline material with the stoichiometry Li2PO2N. The present paper reports the experimental preparation of the material using high temperature solid state synthesis and reports the results of experimental and calculational characterization studies. The so-named SD -Li2PO2N crystal structure has the orthorhombic space group Cmc21 with lattice constants a=9.0692(4) Å, b=5.3999(2) Å, and c=4.6856(2) Å. The structure is similar but not identical to the predicted structure, characterized by parallel arrangements of anionic phosphorus oxy-nitride chains having planar P -N -P -N backbones. Nitrogen 2p π states contribute to the strong bonding and to the chemical and thermal stablility of the material in air up to 600° C and in vacuum up to 1050° C. The measured Arrhenius activation energy for ionic conductivity is 0.6 eV which is comparable to computed vacancy migration energies in the presence of a significant population of Li+ ion vacancies. Supported by NSF grant DMR-1105485 and by a grnat from the Wake Forest University Center for Energy, Environment, and Sustainability.

  5. Electrochemical properties of dual phase neodymium-doped ceria alkali carbonate composite electrolytes in intermediate temperature

    NASA Astrophysics Data System (ADS)

    Kim, Ji-Tae; Lee, Tae-Hee; Park, Ka-Young; Seo, Yongho; Kim, Ki Buem; Song, Sun-Ju; Park, Byoungnam; Park, Jun-Young

    2015-02-01

    Composite electrolyte materials composed of neodymium-doped ceria (Nd0.2Ce0.8O1.9; NDC) and (Li-0.5Na)2CO3 are investigated to understand the unique behaviors of their multi-ionic conduction. In the intermediate temperature, the NDC-based carbonate composite electrolytes exhibit a much higher conductivity compared to pure NDC. It has been claimed that the oxide ions are transported in the doped-ceria phase via oxygen vacancies and the protons are conducted through the second carbonate phase, thereby resulting in an enhanced ionic conductivity. However, it has not been experimentally demonstrated if the proton conduction within the carbonate phase aided in improving the conductivity of oxygen ions in the composite system. Hence, the primary objective of this work is to cultivate a deeper insight into the conduction property of these composites as an attempt to clarify the ionic transport phenomenon responsible for enhanced conductivity. Electrical conductivities of NDC and NDC/carbonate materials are investigated as a function of oxygen partial pressure and vapor pressure of water to understand transport properties of composite electrolytes. The ionic and electronic transference numbers of composite electrolytes are measured by the oxygen- and hydrogen-concentration cells containing water. The dominant charge carriers are identified quantitatively through the analysis of the partial conductivity of proton, oxygen ions, and electrons (holes). Understanding the transport properties and transference numbers of composite electrolytes can contribute to the development of commercial solid oxide fuel cells, which can be done by reducing the operating temperature using a highly ionic conductive NDC/carbonate composite electrolyte at the intermediate temperature.

  6. Electrolytic coloration of hydroxyl-doped potassium iodide polycrystals

    NASA Astrophysics Data System (ADS)

    Wang, Na; Gu, Hongen; Han, Li; Guo, Meili; Qin, Fang

    2007-03-01

    Hydroxyl-doped potassium iodide polycrystals were successfully colored electrolytically by using a pointed cathode and a flat anode at various temperatures and electric field strengths, which mainly benefits appropriate coloration temperatures and electric field strengths. Characteristic OH-, O2--Va+ , U, V2, V3, Cu+, Cu-related, I2- , I2, K, F, R1 and R2 spectral bands were observed in Kubelka-Munk functions of the colored polycrystals, and the OH- and O2--Va+ spectral bands at room temperature were determined from Mollwo-Ivey plots. Color center formation in the electrolytic coloration was explained.

  7. Novel Stable Gel Polymer Electrolyte: Toward a High Safety and Long Life Li-Air Battery.

    PubMed

    Yi, Jin; Liu, Xizheng; Guo, Shaohua; Zhu, Kai; Xue, Hailong; Zhou, Haoshen

    2015-10-28

    Nonaqueous Li-air battery, as a promising electrochemical energy storage device, has attracted substantial interest, while the safety issues derived from the intrinsic instability of organic liquid electrolytes may become a possible bottleneck for the future application of Li-air battery. Herein, through elaborate design, a novel stable composite gel polymer electrolyte is first proposed and explored for Li-air battery. By use of the composite gel polymer electrolyte, the Li-air polymer batteries composed of a lithium foil anode and Super P cathode are assembled and operated in ambient air and their cycling performance is evaluated. The batteries exhibit enhanced cycling stability and safety, where 100 cycles are achieved in ambient air at room temperature. The feasibility study demonstrates that the gel polymer electrolyte-based polymer Li-air battery is highly advantageous and could be used as a useful alternative strategy for the development of Li-air battery upon further application.

  8. Restricting the Solubility of Polysulfides in Li-S Batteries Via Electrolyte Salt Selection

    SciTech Connect

    Chen, Junzheng; Han, Kee Sung; Henderson, Wesley A.; Lau, Kah Chun; Vijayakumar, Murugesan; Dzwiniel, Trevor; Pan, Huilin; Curtiss, Larry A.; Xiao, Jie; Mueller, Karl T.; Shao, Yuyan; Liu, Jun

    2016-03-29

    Polysulfide solubility in the electrolyte has a critical role to the Li-S battery but the mechanism study on the solubility needs to be carefully carried out. In this paper we found that lithium 2-trifluoromethyl-4,5-dicyanoimidazole (LiTDI) reveals a suppression of the polysulfide solubility in electrolytes (relative to the most widely used electrolyte formulation) and the Li-S cells achieved homogeneous stable capacity retention upon extensive cycling and Li metal deposition on the anode. Combined experimental, simulation and calculation methods suggest the dominate disproportionation product of Li2S8 is Li2S4 in the LiTDI electrolyte due to a different interaction between lithium ion and TDI anion. The Li2S4 would continuesly form a Li4S8 dimer and be fully locallized to precipitate out. The use of the electrolyte with the LiTDI salt (with polysulfide and LiNO3 additives) enabled a cell with a high sulfur (3 mg-S cm-2) loading to deliver a 1.67 mAh cm-2 areal capacity after 300 stable cycles at a high current (2.4 mA cm-2) density.

  9. Enhanced Performance of Li|LiFePO4 Cells Using CsPF6 as an Electrolyte Additive

    SciTech Connect

    Xiao, Liang; Chen, Xilin; Cao, Ruiguo; Qian, Jiangfeng; Xiang, Hongfa; Zheng, Jianming; Zhang, Jiguang; Xu, Wu

    2015-10-20

    The practical application of lithium (Li) metal anode in rechargeable Li batteries is hindered by both the growth of Li dendrites and the low Coulombic efficiency (CE) during repeated charge/discharge cycles. Recently, we have discovered that CsPF6 as an electrolyte additive can significantly suppress Li dendrite growth and lead to highly compacted and well aligned Li nanorod structure during Li deposition on copper substrates. In this paper, the effect of CsPF6 additive on the performance of rechargeable Li metal batteries with lithium iron phosphate (LFP) cathode was further studied. Li|LFP coin cells with CsPF6 additive in electrolytes show well protected Li anode surface, decreased resistance, enhanced rate capability and extended cycling stability. In Li|LFP cells, the electrolyte with CsPF6 additive shows excellent long-term cycling stability (at least 500 cycles) at a charge current density of 0.5 mA cm-2 without internal short circuit. At high charge current densities, the effect of CsPF6 additive becomes less significant. Future work needs to be done to protect Li metal anode, especially at high charge current densities and for long cycle life.

  10. Enhanced performance of Li|LiFePO4 cells using CsPF6 as an electrolyte additive

    NASA Astrophysics Data System (ADS)

    Xiao, Liang; Chen, Xilin; Cao, Ruiguo; Qian, Jiangfeng; Xiang, Hongfa; Zheng, Jianming; Zhang, Ji-Guang; Xu, Wu

    2015-10-01

    The practical application of lithium (Li) metal anode in rechargeable Li batteries is hindered by both the growth of Li dendrites and the low Coulombic efficiency (CE) during repeated charge/discharge cycles. Recently, we have discovered that CsPF6 as an electrolyte additive can significantly suppress Li dendrite growth and lead to highly compacted and well aligned Li nanorod structures during Li deposition on copper substrates. In this paper, the effect of CsPF6 additive on the performance of rechargeable Li metal batteries with lithium iron phosphate (LFP) cathode is further studied. Li|LFP coin cells with CsPF6 additive in electrolytes show well protected Li anode surface, decreased resistance, enhanced rate capability and extended cycling stability. In Li|LFP cells, the electrolyte with CsPF6 additive shows excellent long-term cycling stability (at least 500 cycles) at a charge current density of 0.5 mA cm-2 without internal short circuit. At high charge current densities, the effect of CsPF6 additive becomes less significant. Future work needs to be done to protect Li metal anode, especially at high charge current densities and for long cycle life.

  11. Enhanced Cycling Stability of Rechargeable Li-O2 Batteries Using High Concentration Electrolytes

    SciTech Connect

    Liu, Bin; Xu, Wu; Yan, Pengfei; Sun, Xiuliang; Bowden, Mark E.; Read, Jeffrey; Qian, Jiangfeng; Mei, Donghai; Wang, Chong M.; Zhang, Jiguang

    2016-01-26

    The electrolyte stability against reactive reduced-oxygen species is crucial for the development of rechargeable Li-O2 batteries. In this work, we systematically investigated the effect of lithium salt concentration in 1,2-dimethoxyethane (DME)-based electrolytes on the cycling stability of Li-O2 batteries. Cells with high concentration electrolyte illustrate largely enhanced cycling stability under both the full discharge/charge (2.0-4.5 V vs. Li/Li+) and the capacity limited (at 1,000 mAh g-1) conditions. These cells also exhibit much less reaction-residual on the charged air electrode surface, and much less corrosion to the Li metal anode. The density functional theory calculations are conducted on the molecular orbital energies of the electrolyte components and the Gibbs activation barriers for superoxide radical anion to attack DME solvent and Li+-(DME)n solvates. In a highly concentrated electrolyte, all DME molecules have been coordinated with salt and the C-H bond scission of a DME molecule becomes more difficult. Therefore, the decomposition of highly concentrated electrolyte in a Li-O2 battery can be mitigated and both air-cathodes and Li-metal anodes exhibits much better reversibility. As a results, the cyclability of Li-O2 can be largely improved.

  12. Performance of new 10 kW class MCFC using Li/K and Li/Na electrolyte

    SciTech Connect

    Mugikura, Yoshihiro; Yoshiba, Fumihiko; Izaki, Yoshiyuki; Watanabe, Takao

    1996-12-31

    The molten carbonate fuel cell (MCFC) uses generally mixture of lithium carbonate and potassium carbonate (Li/K) as the electrolyte. NiO cathode dissolution is one of serious problems for MCFC life. The NiO cathode has been found to dissolve into the electrolyte as Ni{sup 2+} ion which is reduced to metallic Ni by H{sub 2} in the fuel gas and bridges the anode and the cathode. The bridges short circuit and degrade cell performance and shorten cell life. Since solubility of NiO in mixture of lithium carbonate and sodium carbonate (Li/Na) is lower than in Li/K, it takes longer time to take place slowing by NiO cathode dissolution in Li/Na compared with in Li/K. The ionic conductivity of Li/Na is higher than of Li/K, however, oxygen solubility in Li/Na is lower 9 than in Li/K. A new 10 kW class MCFC stack composed of Li/K cells and Li/Na cells, was tested. Basic performance of the Li/K cells and Li/Na cells of the stack was reported.

  13. Li-ion battery electrolyte formulated for low-temperature applications

    SciTech Connect

    Ein-Eli, Y.; Thomas, S.R.; Chadha, R.; Blakley, T.J.; Koch, V.R.

    1997-03-01

    Low-temperature (<0 C) applications of Li-ion batteries have prompted the search for improved, high-conductivity electrolytes. Because the performance of the carbonaceous anode is highly sensitive to changes in electrolyte composition, the authors focused their efforts on this electrode. Electrolytes containing LiAsF{sub 6}, LiPF{sub 6}, LiN(SO{sub 2}CF{sub 3}){sub 2}[lithium bis(trifluoromethanesulfonyl)imide], or LiIm, and LiC(SO{sub 2}CF{sub 3}){sub 3} [lithium tris(trifluoromethanesulfonyl)methide], or LiMe, in methyl formate (MF)-ethylene carbonate (EC) solvent mixtures were tested in lithium-graphite half-cells. The graphite electrodes could be cycled at ambient temperature with high reversible capacity. The best supporting electrolyte was found to be LiAsF{sub 6}, and the presence of a high concentration of ethylene carbonate and up to 300 ppm H{sub 2}O in the solution considerably increased the reversible capacity upon cycling. The conductivity values of a binary solvent mixture of methyl formate and ethylene carbonate containing LiAsF{sub 6} or LiMe were measured between {minus}40 C and room temperature. Graphite electrodes cycled at {minus}2 C in these electrolytes obtained reasonable reversible capacity, approaching 50%.

  14. Performance and discharge characteristics of doped (beta) MnO2 in H2SO4 electrolyte

    NASA Astrophysics Data System (ADS)

    Desai, Buqui D.; Lobo, Fernando S.; Kamatdalal, V. N.

    1994-10-01

    Doped manganese dioxides (beta-MnO2) were prepared by thermal decomposition (180 C) of manganese nitrate in the presence of weighed quantities of NH4VO3, Na2WO4 center-dot 2H2O, LiNO3, AgNO3, or MoO3. Detailed chemical analyses, surface area, and pycnometric density determinations were carried out, and the electrochemical performance was evaluated in H2SO4 (8 N) electrolyte. The discharge behavior was monitored using constant currents and constant resistances (both continuous and intermittent discharge). Some of the Mo-doped samples together with the Li- and Ag-doped materials performed well as cathodes in H2SO4. The consistency of discharge duration under different discharge regimes was a marked feature of the behavior of some of the compositions.

  15. Towards more thermally stable Li-ion battery electrolytes with salts and solvents sharing nitrile functionality

    NASA Astrophysics Data System (ADS)

    Kerner, Manfred; Lim, Du-Hyun; Jeschke, Steffen; Rydholm, Tomas; Ahn, Jou-Hyeon; Scheers, Johan

    2016-11-01

    The overall safety of Li-ion batteries is compromised by the state-of-the-art electrolytes; the thermally unstable lithium salt, lithium hexafluorophosphate (LiPF6), and flammable carbonate solvent mixtures. The problem is best addressed by new electrolyte compositions with thermally robust salts in low flammability solvents. In this work we introduce electrolytes with either of two lithium nitrile salts, lithium 4,5-dicyano-1,2,3-triazolate (LiDCTA) or lithium 4,5-dicyano-2-trifluoromethylimidazolide (LiTDI), in solvent mixtures with high flashpoint adiponitrile (ADN), as the main component. With sulfolane (SL) and ethylene carbonate (EC) as co-solvents the liquid temperature range of the electrolytes are extended to lower temperatures without lowering the flashpoint, but at the expense of high viscosities and moderate ionic conductivities. The anodic stabilities of the electrolytes are sufficient for LiFePO4 cathodes and can be charged/discharged for 20 cycles in Li/LiFePO4 cells with coulombic efficiencies exceeding 99% at best. The excellent thermal stabilities of the electrolytes with the solvent combination ADN:SL are promising for future electrochemical investigations at elevated temperatures (> 60 °C) to compensate the moderate transport properties and rate capability. The electrolytes with EC as a co-solvent, however, release CO2 by decomposition of EC in presence of a lithium salt, which potentially makes EC unsuitable for any application targeting higher operating temperatures.

  16. Decoupling effective Li+ ion conductivity from electrolyte viscosity for improved room-temperature cell performance

    NASA Astrophysics Data System (ADS)

    Giffin, Guinevere A.; Moretti, Arianna; Jeong, Sangsik; Passerini, Stefano

    2017-02-01

    Ionic liquids are attractive materials for alternative electrolytes to combat the safety issues associated with conventional organic carbonate-based electrolytes. However, the performance of ionic liquid-based cells is generally not competitive as the high viscosity and low conductivity limits the rate performance. The work presented here demonstrates that the drawbacks in terms of rate capability can be overcome through the use of the high lithium concentration Pyr12O1FTFSI0.6LiFTFSI0.4 electrolyte. Despite an order of magnitude difference in the conductivity and viscosity, this high concentration electrolyte outperforms the lithium-dilute electrolyte with the same components in terms of rate capability in Li metal/LFP cells and LTO/LFP cells. The results suggest that the effective Li ion transport in the concentrated electrolyte is higher than in the dilute solution.

  17. Effect of organic solvents on Li+ ion solvation and transport in ionic liquid electrolytes: a molecular dynamics simulation study.

    PubMed

    Li, Zhe; Borodin, Oleg; Smith, Grant D; Bedrov, Dmitry

    2015-02-19

    Molecular dynamics simulations of N-methyl-N-propylpyrrolidinium (pyr13) bis(trifluoromethanesulfonyl)imide (Ntf2) ionic liquid [pyr13][Ntf2] doped with [Li][Ntf2] salt and mixed with acetonitrile (AN) and ethylene carbonate (EC) organic solvents were conducted using polarizable force field. Structural and transport properties of ionic liquid electrolytes (ILEs) with 20 and 40 mol % of organic solvents have been investigated and compared to properties of neat ILEs. Addition of AN and EC solvents to ILEs resulted in the partial displacement of the Ntf2 anions from the Li(+) first coordination shell by EC and AN and shifting the Li-Ntf2 coordination from bidentate to monodentate. The presence of organic solvents in ILE has increased the ion mobility, with the largest effect observed for the Li(+) cation. The Li(+) conductivity has doubled with addition of 40 mol % of AN. The Li(+)-N(Ntf2) residence times were dramatically reduced with addition of solvents, indicating an increasing contribution from structural diffusion of the Li(+) cations.

  18. Ionic liquid electrolytes for Li-air batteries: lithium metal cycling.

    PubMed

    Grande, Lorenzo; Paillard, Elie; Kim, Guk-Tae; Monaco, Simone; Passerini, Stefano

    2014-05-08

    In this work, the electrochemical stability and lithium plating/stripping performance of N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) are reported, by investigating the behavior of Li metal electrodes in symmetrical Li/electrolyte/Li cells. Electrochemical impedance spectroscopy measurements and galvanostatic cycling at different temperatures are performed to analyze the influence of temperature on the stabilization of the solid electrolyte interphase (SEI), showing that TFSI-based ionic liquids (ILs) rank among the best candidates for long-lasting Li-air cells.

  19. Structure and Stoichiometry in doped LLZO (Li7La3Zr2O12)

    NASA Astrophysics Data System (ADS)

    Johannes, Michelle; Bernstein, Noam; Huq, Ashfia; Mukhopadyay, Saikat; Wolfenstine, Jeff; Allen, Jan; Thompsen, Travis; Sakamoto, Jeff; Stewart, Derek

    2015-03-01

    LLZO has a tetragonal, Li-ordered phase with very low ionic conductivity and a cubic, Li-disordered phase with two orders of magnitude higher conductivity, relevant for solid electrolyte usage. The jump in conductivity can be correlated to dopant-induced Li vacancies that disorder the Li sublattice and cause the structural phase transition. In this work, we use extremely careful synthesis, neutron diffraction, synchrotron XRD, Raman scattering, and first principles techniques to show how both overall structure and selected local structural elements change as a function of dopant concentration. In particular, we examine how the local structure that defines the Li ion pathways changes with the lattice constant and how important microscopic quantities such as different Li site energies and hopping barriers change accordingly. Our work provides a link between the easily measurable lattice constant and extremely important but difficult to measure performance indicators such as exact Li vacancy concentration and hopping energy barriers. We hope that the ``map'' between structure and property provided here will speed optimization of the ionic conductivity via targeted doping strategies.

  20. Nitrogen-doped carbon nanofibers derived from polypyrrole coated bacterial cellulose as high-performance electrode materials for supercapacitors and Li-ion batteries

    SciTech Connect

    Lei, Wen; Han, Lili; Xuan, Cuijuan; Lin, Ruoqian; Liu, Hongfang; Xin, Huolin L.; Wang, Deli

    2016-05-24

    Here, nitrogen-doped carbon nanofiber (NDCN) was synthesized via carbonization of polypyrrole (PPy) coated bacterial cellulose (BC) composites, where BC serves as templates as well as precursor, and PPy serves as the nitrogen source. The synthesized NDCN was employed as electrode for both supercapacitors and Li-ion batteries. The large surface area exposed to electrolyte resulting from the 3D carbon networks leads to sufficient electrode/electrolyte interface and creates shorter transport paths of electrolyte ions and Li+ ion. Besides, the three types of N dopants in NDCN improve the electronic conductivity, as well as superior electrochemical performance.

  1. Nitrogen-doped carbon nanofibers derived from polypyrrole coated bacterial cellulose as high-performance electrode materials for supercapacitors and Li-ion batteries

    DOE PAGES

    Lei, Wen; Han, Lili; Xuan, Cuijuan; ...

    2016-05-24

    Here, nitrogen-doped carbon nanofiber (NDCN) was synthesized via carbonization of polypyrrole (PPy) coated bacterial cellulose (BC) composites, where BC serves as templates as well as precursor, and PPy serves as the nitrogen source. The synthesized NDCN was employed as electrode for both supercapacitors and Li-ion batteries. The large surface area exposed to electrolyte resulting from the 3D carbon networks leads to sufficient electrode/electrolyte interface and creates shorter transport paths of electrolyte ions and Li+ ion. Besides, the three types of N dopants in NDCN improve the electronic conductivity, as well as superior electrochemical performance.

  2. The use of Electrolyte Additives to Improve the High Temperature Resilience of Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Lucht, B. L.; Ratnakumar, Bugga V.

    2007-01-01

    This viewgraph presentation reviews the use of electrolyte additves to improve the resillience of Lithium ion cells. The objective of this work is to identify lithium-ion electrolytes, which will lead to Li-ion cells with a wide operational temperature range (+60 to -60 C), and to develop Li-ion electrolytes which result in cells that display improved high temperature resilience. Significant improvement in the high temperature resilience of Li-ion cells containing these additives was observed, with the most dramatic benefit being displayed by addition of DMAc. When the electrochemical properties of the individual electrodes were analyzed, the degradation of the anode kinetics was slowed most dramatically by the incorporation of DMAc into the electrolytes. Whereas, the greatest retention in the cathode kinetics was observed in the cell containing the electrolyte with VC added.

  3. First principles simulations of structural phase transformations in the solid electrolyte LiBH4 with chemical substitutions

    NASA Astrophysics Data System (ADS)

    Bernstein, Noam; Hoang, Khang; Johannes, Michelle

    2014-03-01

    The proposed hydrogen storage material LiBH4 has been shown to have possible applications as a Li-ion battery solid electrolyte, due to its high Li-ion conductivity over 10-3 S/cm-1 [1], comparable to polymer gel electrolytes. The high conductivity is only observed above a phase transition temperature that is outside of the useful operating range, but doping the material with various substitutions for the Li or BH4 units can bring the phase transition below room temperature. Both smaller and larger substituting species can stabilize the high T structure, indicating that it is not a simple volume effect. We show that variable-cell-shape molecular-dynamics simulations using density functional theory forces and stresses reproduce the structural phase transition. Using umbrella integration to compute the free energy differences between the two structures, we calculate the phase transition temperature and its dependence on substitutional I, Cl, and Na concentrations, and show that they are in very good agreement with experiment. We calculate the effect of K substitution, and predict that it will be even more effective at stabilizing the high T structure. Decomposing the free energy difference changes into enthalpy and entropy contributions shows that the mechanis

  4. Studies on the thermal behavior of CS:LiTFSI:[Amim] Cl polymer electrolytes exerted by different [Amim] Cl content

    NASA Astrophysics Data System (ADS)

    Ramesh, S.; Shanti, R.; Morris, Ezra

    2012-01-01

    The principle motivation of this research work is to develop environmental-friendly polymer electrolytes utilizing corn starch (CS), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1-allyl-3-methylimidazolium chloride ([Amim] Cl) by solution casting technique. The highest ionic conductivity value was achieved for the composition CS:LiTFSI:[Amim] Cl (14 wt. %:6 wt. %:80 wt. %) which exhibits the ionic conductivity value of 5.68 × 10 -2 S cm -1 at 40 °C with the activation energy of 4.86 kJ mol -1. This sample possess high concentration of amorphous phase coupled with greater presence of conducting cations (lithium, Li + and imidazolium, [Amim] +) as depicted by the dielectric loss tangent plot. The conductivity-temperature plots were found to obey Arrhenius rule in which the conductivity mechanism is thermally assisted. The melting temperature of polymer electrolyte decreases with increase in [Amim] Cl content. This is attributed to the good miscibility of [Amim] Cl in CS:LiTFSI matrix inducing structural disorderliness. Reference to the TGA results it is found that the addition of [Amim] Cl diminishes the heat-resistivity whereas enhancement in the thermal stability occurred at the initial addition and declines with further doping of [Amim] Cl.

  5. Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon.

    PubMed

    Soto, Fernando A; Yan, Pengfei; Engelhard, Mark H; Marzouk, Asma; Wang, Chongmin; Xu, Guiliang; Chen, Zonghai; Amine, Khalil; Liu, Jun; Sprenkle, Vincent L; El-Mellouhi, Fedwa; Balbuena, Perla B; Li, Xiaolin

    2017-03-07

    Solid-electrolyte interphase (SEI) films with controllable properties are highly desirable for improving battery performance. In this paper, a combined experimental and theoretical approach is used to study SEI films formed on hard carbon in Li- and Na-ion batteries. It is shown that a stable SEI layer can be designed by precycling an electrode in a desired Li- or Na-based electrolyte, and that ionic transport can be kinetically controlled. Selective Li- and Na-based SEI membranes are produced using Li- or Na-based electrolytes, respectively. The Na-based SEI allows easy transport of Li ions, while the Li-based SEI shuts off Na-ion transport. Na-ion storage can be manipulated by tuning the SEI layer with film-forming electrolyte additives, or by preforming an SEI layer on the electrode surface. The Na specific capacity can be controlled to < 25 mAh g(-1) ; ≈ 1/10 of the normal capacity (250 mAh g(-1) ). Unusual selective/preferential transport of Li ions is demonstrated by preforming an SEI layer on the electrode surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion-selective conductors using electrochemical approaches.

  6. Physicochemical Properties of Industrial Aluminum Electrolytes Enriching Li and K: The Liquidus Temperature

    NASA Astrophysics Data System (ADS)

    Lv, Xiao-jun; Shuang, Ya-jing; Li, Jie; Chen, Shi-yue; Lai, Yan-qing; Zhang, Hong-liang; Liu, Ye-xiang

    2017-04-01

    The alumina contains plenty of Li2O and K2O as a result of using low-grade bauxite in China. Thus, LiF and KF will be enriched in the electrolytes with the operation of the cell, so that the composition and physicochemical properties of electrolytes have been changed. The effects of LiF, KF, and CR on the liquidus temperature of electrolytes based on the xNaF·AlF3-5 wt pct CaF2-2.5 wt pct Al2O3-0.5 wt pct MgF2 system have been investigated in this study. The results show that the liquidus temperature decreases by 5.13 K to 10.74 K (5.13 °C to 10.74 °C) per 1 wt pct addition of LiF and that the liquidus temperature decreases by 1.63 K to 3.8 K (1.63 °C to 3.8 °C) with per 1 wt pct addition of KF. When adding LiF and KF together, it has the interplay between LiF and KF. Under different electrolyte systems, the interplay between LiF and KF is complex. The effect of CR on liquidus temperature has been related to the concentration of LiF and KF.

  7. Recent progress in theoretical and computational investigations of Li-ion battery materials and electrolytes.

    PubMed

    Bhatt, Mahesh Datt; O'Dwyer, Colm

    2015-02-21

    There is an increasing worldwide demand for high energy density batteries. In recent years, rechargeable Li-ion batteries have become important power sources, and their performance gains are driving the adoption of electrical vehicles (EV) as viable alternatives to combustion engines. The exploration of new Li-ion battery materials is an important focus of materials scientists and computational physicists and chemists throughout the world. The practical applications of Li-ion batteries and emerging alternatives may not be limited to portable electronic devices and circumventing hurdles that include range anxiety and safety among others, to their widespread adoption in EV applications in the future requires new electrode materials and a fuller understanding of how the materials and the electrolyte chemistries behave. Since this field is advancing rapidly and attracting an increasing number of researchers, it is crucial to summarise the current progress and the key scientific challenges related to Li-ion batteries from theoretical point of view. Computational prediction of ideal compounds is the focus of several large consortia, and a leading methodology in designing materials and electrolytes optimized for function, including those for Li-ion batteries. In this Perspective, we review the key aspects of Li-ion batteries from theoretical perspectives: the working principles of Li-ion batteries, the cathodes, anodes, and electrolyte solutions that are the current state of the art, and future research directions for advanced Li-ion batteries based on computational materials and electrolyte design.

  8. Interfacial Stability of Li Metal-Solid Electrolyte Elucidated via in Situ Electron Microscopy.

    PubMed

    Ma, Cheng; Cheng, Yongqiang; Yin, Kuibo; Luo, Jian; Sharafi, Asma; Sakamoto, Jeff; Li, Juchuan; More, Karren L; Dudney, Nancy J; Chi, Miaofang

    2016-11-09

    Despite their different chemistries, novel energy-storage systems, e.g., Li-air, Li-S, all-solid-state Li batteries, etc., face one critical challenge of forming a conductive and stable interface between Li metal and a solid electrolyte. An accurate understanding of the formation mechanism and the exact structure and chemistry of the rarely existing benign interfaces, such as the Li-cubic-Li7-3xAlxLa3Zr2O12 (c-LLZO) interface, is crucial for enabling the use of Li metal anodes. Due to spatial confinement and structural and chemical complications, current investigations are largely limited to theoretical calculations. Here, through an in situ formation of Li-c-LLZO interfaces inside an aberration-corrected scanning transmission electron microscope, we successfully reveal the interfacial chemical and structural progression. Upon contact with Li metal, the LLZO surface is reduced, which is accompanied by the simultaneous implantation of Li(+), resulting in a tetragonal-like LLZO interphase that stabilizes at an extremely small thickness of around five unit cells. This interphase effectively prevented further interfacial reactions without compromising the ionic conductivity. Although the cubic-to-tetragonal transition is typically undesired during LLZO synthesis, the similar structural change was found to be the likely key to the observed benign interface. These insights provide a new perspective for designing Li-solid electrolyte interfaces that can enable the use of Li metal anodes in next-generation batteries.

  9. LiPF 6 and lithium oxalyldifluoroborate blend salts electrolyte for LiFePO 4/artificial graphite lithium-ion cells

    NASA Astrophysics Data System (ADS)

    Zhang, Zhian; Chen, Xujie; Li, Fanqun; Lai, Yanqing; Li, Jie; Liu, Ping; Wang, Xinyu

    The electrochemical behaviors of LiPF 6 and lithium oxalyldifluoroborate (LiODFB) blend salts in ethylene carbonate + propylene carbonate + dimethyl carbonate (EC + PC + DMC, 1:1:3, v/v/v) for LiFePO 4/artificial graphite (AG) lithium-ion cells have been investigated in this work. It is demonstrated by conductivity test that LiPF 6 and LiODFB blend salts electrolytes have superior conductivity to pure LiODFB-based electrolyte. The results show that the performances of LiFePO 4/Li half cells with LiPF 6 and LiODFB blend salts electrolytes are inferior to pure LiPF 6-based electrolyte, the capacity and cycling efficiency of Li/AG half cells are distinctly improved by blend salts electrolytes, and the optimum LiODFB/LiPF 6 molar ratio is around 4:1. A reduction peak is observed around 1.5 V in LiODFB containing electrolyte systems by means of CV tests for Li/AG cells. Excellent capacity and cycling performance are obtained on LiFePO 4/AG 063048-type cells tests with blend salts electrolytes. A plateau near 1.7-2.0 V is shown in electrolytes containing LiODFB salt, and extends with increasing LiODFB concentration in charge curve of LiFePO 4/AG cells. At 1 C discharge current rate, the initial discharge capacity of 063048-type cell with the optimum electrolyte is 376.0 mAh, and the capacity retention is 90.8% after 100 cycles at 25 °C. When at 65 °C, the capacity and capacity retention after 100 cycles are 351.3 mAh and 88.7%, respectively. The performances of LiFePO 4/AG cells are remarkably improved by blending LiODFB and LiPF 6 salts compared to those of pure LiPF 6-based electrolyte system, especially at elevated temperature to 65 °C.

  10. Structure and Stoichiometry in Supervalent Doped Li7La3 Zr2O12

    DOE PAGES

    Mukhopadhyay, Saikat; Thompson, Travis; Sakamoto, Jeff; ...

    2015-04-20

    The oxide garnet material Li7La3 Zr2O12 shows remarkably high ionic conductivity when doped with supervalent ions that are charge compensated by Li vacancies and is currently one of the best candidates for development of a technologically relevant solid electrolyte. Determination of optimal dopant concentration, however, has remained a persistent problem due to the extreme difficulty of establishing the actual (as compared to nominal) stoichiometry of intentionally doped materials and by the fact that it is still not entirely clear what level of lattice expansion/contraction best promotes. ionic diffusion. By combining careful synthesis, neutron diffraction, high-resolution X-ray diffraction (XRD), Raman measurements,more » and density functional theory calculations, we show that structure and stoichiometry are intimately related such that the former can in many cases be used as a gauge of the latter. We show that different Li-vacancy creating supervalent ions (Al3+ vs Ta5+) affect the structure very differently, both in terms of the lattice constant, which is easily measurable, and hi terms of the local structure, which can be difficult or impossible to access experimentally but may have important ramifications for conduction. We carefully correlate the lattice constant to dopant type/concentration via Vegard's law and then further correlate these quantities to relevant local structural parameters. In conclusion, our work opens the possibility of developing a codopant scheme that optimizes the Li vacancy concentration and the lattice size simultaneously.« less

  11. Nitrogen-Doped Hollow Carbon Nanospheres for High-Performance Li-Ion Batteries.

    PubMed

    Yang, Yufen; Jin, Song; Zhang, Zhen; Du, Zhenzhen; Liu, Huarong; Yang, Jia; Xu, Hangxun; Ji, Hengxing

    2017-04-13

    N-doped carbon materials is of particular attraction for anodes of lithium-ion batteries (LIBs) because of their high surface areas, superior electrical conductivity, and excellent mechanical strength, which can store energy by adsorption/desorption of Li(+) at the interfaces between the electrolyte and electrode. By directly carbonization of zeolitic imidazolate framework-8 nanospheres synthesized by an emulsion-based interfacial reaction, we obtained N-doped hollow carbon nanospheres with tunable shell thickness (20 nm to solid sphere) and different N dopant concentrations (3.9 to 21.7 at %). The optimized anode material possessed a shell thickness of 20 nm and contained 16.6 at % N dopants that were predominately pyridinic and pyrrolic. The anode delivered a specific capacity of 2053 mA h g(-1) at 100 mA g(-1) and 879 mA h g(-1) at 5 A g(-1) for 1000 cycles, implying a superior cycling stability. The improved electrochemical performance can be ascribed to (1) the Li(+) adsorption dominated energy storage mechanism prevents the volume change of the electrode materials, (2) the hollow nanostructure assembled by the nanometer-sized primary particles prevents the agglomeration of the nanoparticles and favors for Li(+) diffusion, (3) the optimized N dopant concentration and configuration facilitate the adsorption of Li(+); and (4) the graphitic carbon nanostructure ensures a good electrical conductivity.

  12. Al-doped Li7La3Zr2O12 synthesized by a polymerized complex method

    NASA Astrophysics Data System (ADS)

    Jin, Ying; McGinn, Paul J.

    2011-10-01

    Li7La3Zr2O12 electrolytes doped with different amounts of Al (0, 0.2, 0.7, 1.2, and 2.5 wt.%) were prepared by a polymerized complex (Pechini) method. The influence of aluminum on the structure and conductivity of Li7La3Zr2O12 were investigated by X-ray diffraction (XRD), impedance spectroscopy, scanning electron microscopy (SEM), and thermal dilatometry. It was found that even a small amount of Al (e.g. 0.2 wt.%) added to Li7La3Zr2O12 can greatly accelerate densification during the sintering process. SEM micrographs showed the existence of a liquid phase introduced by Al additions which led to the enhanced sintering rate. The addition of Al also stabilized the higher conductivity cubic form of Li7La3Zr2O12 rather than the less conductive tetragonal form. The combination of these two beneficial effects of Al enabled greatly reduced sintering times for preparation of highly conductive Li7La3Zr2O12 electrolyte. With optimal additions of Al (e.g. 1.2 wt.%), Li7La3Zr2O12 electrolyte sintered at 1200 °C for only 6 h showed an ionic conductivity of 2.0 × 10-4 S cm-1 at room temperature.

  13. A flexible Li polymer primary cell with a novel gel electrolyte based on poly(acrylonitrile)

    NASA Astrophysics Data System (ADS)

    Akashi, Hiroyuki; Tanaka, Ko-ichi; Sekai, Koji

    The performance of a Li polymer primary cell with fire-retardant poly(acrylonitrile) (PAN)-based gel electrolytes is reported. By optimizing electrodes, electrolytes, the packaging material, and the structural design of the polymer cell, we succeeded in developing a "film-like" Li polymer primary cell with sufficient performance for practical use. The cell is flexible and less than 0.5 mm thick, which makes it suitable for a power source for some smart devices, such as an IC card. Fast cation conduction in the gel electrolyte minimizes the drop of the discharge capacity even at -20 °C. The high chemical stability of the gel electrolytes and the new packaging material allow the self-discharge rate to be limited to under 4.3%, which is equivalent to that of conventional coin-shaped or cylindrical Li-MnO 2 cells.

  14. Robust cycling of Li-O2 batteries through the synergistic effect of blended electrolytes.

    PubMed

    Kim, Byung Gon; Lee, Je-Nam; Lee, Dong Jin; Park, Jung-Ki; Choi, Jang Wook

    2013-03-01

    Despite their exceptionally large specific capacities, the use of Li-O2 batteries has been limited because of their poor cycle lives, which originates from irreversible reaction processes during each cycle. Recent investigations have found that electrolyte decomposition is one of the most critical reasons for capacity decay. Herein, we report that a blended electrolyte, consisting of a carbonate solvent and an ionic liquid, improves the cycle lives of Li-O2 batteries remarkably through a synergistic effect from both components. Both electrolyte components perform complementary functions to each other: The ionic liquid suppresses the decomposition of the carbonate solvent, and the carbonate solvent resolves the poor ionic conductivity of the ionic liquid. This study confirms the importance and opportunities for the use of electrolytes in Li-O2 batteries.

  15. Alkyl Pyrocarbonate Electrolyte Additives for Performance Enhancement of Li Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Surampudi, S.

    2000-01-01

    Lithium ion rechargeable batteries are being developed for various aerospace applications under a NASA-DoD Interagency program. These applications require further improvements in several areas, specifically in the cycle life for LEO and GEO satellites and in the low temperature performance for the Mars Lander and Rover missions. Accordingly, we have been pursuing research studies to achieve improvement in the low temperature performance, long cycle life and active life of Li ion cells. The studies are mainly focused on electrolytes, to identify newer formulations of new electrolyte additives to enhance Li permeability (at low temperatures) and stability towards the electrode. The latter approach is particularly aimed at the formation suitable SEI (solid electrolyte interphase) on carbon electrodes. In this paper, we report the beneficial effect of using alkyl pyrocarbonates as electrolyte additives to improve the low temperature performance of Li ion cells.

  16. Enhanced ionic conductivity with Li7O2Br3 phase in Li3OBr anti-perovskite solid electrolyte

    NASA Astrophysics Data System (ADS)

    Zhu, Jinlong; Li, Shuai; Zhang, Yi; Howard, John W.; Lü, Xujie; Li, Yutao; Wang, Yonggang; Kumar, Ravhi S.; Wang, Liping; Zhao, Yusheng

    2016-09-01

    Cubic anti-perovskites with general formula Li3OX (X = Cl, Br, I) were recently reported as superionic conductors with the potential for use as solid electrolytes in all-solid-state lithium ion batteries. These electrolytes are nonflammable, low-cost, and suitable for thermoplastic processing. However, the primary obstacle of its practical implementation is the relatively low ionic conductivity at room temperature. In this work, we synthesized a composite material consisting of two anti-perovskite phases, namely, cubic Li3OBr and layered Li7O2Br3, by solid state reaction routes. The results indicate that with the phase fraction of Li7O2Br3 increasing to 44 wt. %, the ionic conductivity increased by more than one order of magnitude compared with pure phase Li3OBr. Formation energy calculations revealed the meta-stable nature of Li7O2Br3, which supports the great difficulty in producing phase-pure Li7O2Br3 at ambient pressure. Methods of obtaining phase-pure Li7O2Br3 will continue to be explored, including both high pressure and metathesis techniques.

  17. Enhanced ionic conductivity with Li7O2Br3 phase in Li3OBr anti-perovskite solid electrolyte

    DOE PAGES

    Zhu, Jinlong; Li, Shuai; Zhang, Yi; ...

    2016-09-07

    Cubic anti-perovskites with general formula Li3OX (X = Cl, Br, I) were recently reported as superionic conductors with the potential for use as solid electrolytes in all-solid-state lithium ion batteries. These electrolytes are nonflammable, low-cost, and suitable for thermoplastic processing. However, the primary obstacle of its practical implementation is the relatively low ionic conductivity at room temperature. In this work, we synthesized a composite material consisting of two anti-perovskite phases, namely, cubic Li3OBr and layered Li7O2Br3, by solid state reaction routes. The results indicate that with the phase fraction of Li7O2Br3 increasing to 44 wt. %, the ionic conductivity increasedmore » by more than one order of magnitude compared with pure phase Li3OBr. Formation energy calculations revealed the meta-stable nature of Li7O2Br3, which supports the great difficulty in producing phase-pure Li7O2Br3 at ambient pressure. Here, methods of obtaining phase-pure Li7O2Br3 will continue to be explored, including both high pressure and metathesis techniques.« less

  18. Wide Operating Temperature Range Electrolytes for High Voltage and High Specific Energy Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Hwang, C.; Krause, F. C.; Soler, J.; West, W. C.; Ratnakumar, B. V.; Amine, K.

    2012-01-01

    A number of electrolyte formulations that have been designed to operate over a wide temperature range have been investigated in conjunction with layered-layered metal oxide cathode materials developed at Argonne. In this study, we have evaluated a number of electrolytes in Li-ion cells consisting of Conoco Phillips A12 graphite anodes and Toda HE5050 Li(1.2)Ni(0.15)Co(0.10)Mn(0.55)O2 cathodes. The electrolytes studied consisted of LiPF6 in carbonate-based electrolytes that contain ester co-solvents with various solid electrolyte interphase (SEI) promoting additives, many of which have been demonstrated to perform well in 4V systems. More specifically, we have investigated the performance of a number of methyl butyrate (MB) containing electrolytes (i.e., LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + MB (20:20:60 v/v %) that contain various additives, including vinylene carbonate, lithium oxalate, and lithium bis(oxalato)borate (LiBOB). When these systems were evaluated at various rates at low temperatures, the methyl butyrate-based electrolytes resulted in improved rate capability compared to cells with all carbonate-based formulations. It was also ascertained that the slow cathode kinetics govern the generally poor rate capability at low temperature in contrast to traditionally used LiNi(0.80)Co(0.15)Al(0.05)O2-based systems, rather than being influenced strongly by the electrolyte type.

  19. Inorganic-organic polymer electrolytes based on poly(vinyl alcohol) and borane/poly(ethylene glycol) monomethyl ether for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Aydın, Hamide; Şenel, Mehmet; Erdemi, Hamit; Baykal, Abdülhadi; Tülü, Metin; Ata, Ali; Bozkurt, Ayhan

    In this study, poly(vinyl alcohol) (PVA) was modified with poly(ethylene glycol) monomethyl ether (PEGME) using borane-tetrahydrofuran (BH 3/THF) complex. Molecular weights of both PVA and PEGME were varied prior to reaction. Boron containing comb-branched copolymers were produced and abbreviated as PVA1PEGMEX and PVA2PEGMEX. Then polymer electrolytes were successfully prepared by doping of the host matrix with CF 3SO 3Li at several stoichiomeric ratios with respect to EO to Li. The materials were characterized via nuclear magnetic resonance (1H NMR and 11B NMR), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG) and differential scanning calorimeter (DSC). The ionic conductivity of these novel polymer electrolytes were studied by dielectric-impedance spectroscopy. Li-ion conductivity of these polymer electrolytes depends on the length of the side units as well as the doping ratio. Such electrolytes possess satisfactory ambient temperature ionic conductivity (>10 -4 S cm -1). Cyclic voltammetry results illustrated that the electrochemical stability domain extends over 4 V.

  20. Role of the solid electrolyte interphase on a Li metal anode in a dimethylsulfoxide-based electrolyte for a lithium-oxygen battery

    NASA Astrophysics Data System (ADS)

    Togasaki, Norihiro; Momma, Toshiyuki; Osaka, Tetsuya

    2015-10-01

    The effect of the solid electrolyte interphase (SEI) on a Li anode on the charge-discharge cycling performance in 1 M LiTFSI/dimethylsulfoxide electrolyte solution is examined by using charge-discharge cycling. The chemical structure of the surface and interior of the SEI strongly affects the cycling performance of the anode. The observed coulombic efficiency is low (<45%) when organic compounds such as lithium alkyl carbonates and polycarbonate form predominantly on the surface and interior. However, when inorganic compounds such as Li2CO3, Li2O, and LiF form instead, the coulombic efficiency increases to >85%. This enhanced efficiency remains constant regardless of the O2 content and despite <1000 ppm concentration of the contaminant H2O in the electrolyte. Thus, the lithium surface should be protected by inorganic compounds prior to cycling to prevent it from undergoing side reactions with the electrolyte during cycling in the electrolyte.

  1. Lithium Ion Pathway within Li7 La3 Zr2 O12 -Polyethylene Oxide Composite Electrolytes.

    PubMed

    Zheng, Jin; Tang, Mingxue; Hu, Yan-Yan

    2016-09-26

    Polymer-ceramic composite electrolytes are emerging as a promising solution to deliver high ionic conductivity, optimal mechanical properties, and good safety for developing high-performance all-solid-state rechargeable batteries. Composite electrolytes have been prepared with cubic-phase Li7 La3 Zr2 O12 (LLZO) garnet and polyethylene oxide (PEO) and employed in symmetric lithium battery cells. By combining selective isotope labeling and high-resolution solid-state Li NMR, we are able to track Li ion pathways within LLZO-PEO composite electrolytes by monitoring the replacement of (7) Li in the composite electrolyte by (6) Li from the (6) Li metal electrodes during battery cycling. We have provided the first experimental evidence to show that Li ions favor the pathway through the LLZO ceramic phase instead of the PEO-LLZO interface or PEO. This approach can be widely applied to study ion pathways in ionic conductors and to provide useful insights for developing composite materials for energy storage and harvesting.

  2. A Rechargeable Li-Air Fuel Cell Battery Based on Garnet Solid Electrolytes.

    PubMed

    Sun, Jiyang; Zhao, Ning; Li, Yiqiu; Guo, Xiangxin; Feng, Xuefei; Liu, Xiaosong; Liu, Zhi; Cui, Guanglei; Zheng, Hao; Gu, Lin; Li, Hong

    2017-01-24

    Non-aqueous Li-air batteries have been intensively studied in the past few years for their theoretically super-high energy density. However, they cannot operate properly in real air because they contain highly unstable and volatile electrolytes. Here, we report the fabrication of solid-state Li-air batteries using garnet (i.e., Li6.4La3Zr1.4Ta0.6O12, LLZTO) ceramic disks with high density and ionic conductivity as the electrolytes and composite cathodes consisting of garnet powder, Li salts (LiTFSI) and active carbon. These batteries run in real air based on the formation and decomposition at least partially of Li2CO3. Batteries with LiTFSI mixed with polyimide (PI:LiTFSI) as a binder show rechargeability at 200 °C with a specific capacity of 2184 mAh g(-1)carbon at 20 μA cm(-2). Replacement of PI:LiTFSI with LiTFSI dissolved in polypropylene carbonate (PPC:LiTFSI) reduces interfacial resistance, and the resulting batteries show a greatly increased discharge capacity of approximately 20300 mAh g(-1)carbon and cycle 50 times while maintaining a cutoff capacity of 1000 mAh g(-1)carbon at 20 μA cm(-2) and 80 °C. These results demonstrate that the use of LLZTO ceramic electrolytes enables operation of the Li-air battery in real air at medium temperatures, leading to a novel type of Li-air fuel cell battery for energy storage.

  3. A Rechargeable Li-Air Fuel Cell Battery Based on Garnet Solid Electrolytes

    NASA Astrophysics Data System (ADS)

    Sun, Jiyang; Zhao, Ning; Li, Yiqiu; Guo, Xiangxin; Feng, Xuefei; Liu, Xiaosong; Liu, Zhi; Cui, Guanglei; Zheng, Hao; Gu, Lin; Li, Hong

    2017-01-01

    Non-aqueous Li-air batteries have been intensively studied in the past few years for their theoretically super-high energy density. However, they cannot operate properly in real air because they contain highly unstable and volatile electrolytes. Here, we report the fabrication of solid-state Li-air batteries using garnet (i.e., Li6.4La3Zr1.4Ta0.6O12, LLZTO) ceramic disks with high density and ionic conductivity as the electrolytes and composite cathodes consisting of garnet powder, Li salts (LiTFSI) and active carbon. These batteries run in real air based on the formation and decomposition at least partially of Li2CO3. Batteries with LiTFSI mixed with polyimide (PI:LiTFSI) as a binder show rechargeability at 200 °C with a specific capacity of 2184 mAh g‑1carbon at 20 μA cm‑2. Replacement of PI:LiTFSI with LiTFSI dissolved in polypropylene carbonate (PPC:LiTFSI) reduces interfacial resistance, and the resulting batteries show a greatly increased discharge capacity of approximately 20300 mAh g‑1carbon and cycle 50 times while maintaining a cutoff capacity of 1000 mAh g‑1carbon at 20 μA cm‑2 and 80 °C. These results demonstrate that the use of LLZTO ceramic electrolytes enables operation of the Li-air battery in real air at medium temperatures, leading to a novel type of Li-air fuel cell battery for energy storage.

  4. A Rechargeable Li-Air Fuel Cell Battery Based on Garnet Solid Electrolytes

    PubMed Central

    Sun, Jiyang; Zhao, Ning; Li, Yiqiu; Guo, Xiangxin; Feng, Xuefei; Liu, Xiaosong; Liu, Zhi; Cui, Guanglei; Zheng, Hao; Gu, Lin; Li, Hong

    2017-01-01

    Non-aqueous Li-air batteries have been intensively studied in the past few years for their theoretically super-high energy density. However, they cannot operate properly in real air because they contain highly unstable and volatile electrolytes. Here, we report the fabrication of solid-state Li-air batteries using garnet (i.e., Li6.4La3Zr1.4Ta0.6O12, LLZTO) ceramic disks with high density and ionic conductivity as the electrolytes and composite cathodes consisting of garnet powder, Li salts (LiTFSI) and active carbon. These batteries run in real air based on the formation and decomposition at least partially of Li2CO3. Batteries with LiTFSI mixed with polyimide (PI:LiTFSI) as a binder show rechargeability at 200 °C with a specific capacity of 2184 mAh g−1carbon at 20 μA cm−2. Replacement of PI:LiTFSI with LiTFSI dissolved in polypropylene carbonate (PPC:LiTFSI) reduces interfacial resistance, and the resulting batteries show a greatly increased discharge capacity of approximately 20300 mAh g−1carbon and cycle 50 times while maintaining a cutoff capacity of 1000 mAh g−1carbon at 20 μA cm−2 and 80 °C. These results demonstrate that the use of LLZTO ceramic electrolytes enables operation of the Li-air battery in real air at medium temperatures, leading to a novel type of Li-air fuel cell battery for energy storage. PMID:28117359

  5. Dendrite-Free Li Deposition Using Trace-Amounts of Water as an Electrolyte Additive

    SciTech Connect

    Qian, Jiangfeng; Xu, Wu; Bhattacharya, Priyanka; Engelhard, Mark H.; Henderson, Wesley A.; Zhang, Yaohui; Zhang, Jiguang

    2015-07-01

    Residual water presents in nonaqueous electrolytes has been widely regarded as a detrimental factor for lithium (Li) batteries. This is because water is highly reactive with the commonly used LiPF6 salt and leads to the formation of HF that corrodes battery materials. In this work, we demonstrate that a controlled trace-amount of water (25-100 ppm) can be an effective electrolyte additive for achieving dendrite-free Li metal deposition in LiPF6-based electrolytes and avoid its detrimental effect at the same time. Detailed analyses reveal that the trace amount of HF formed by the decomposition reaction of LiPF6 with water will be electrochemically reduced during initial Li deposition process to form a uniform and dense LiF-rich SEI layer on the surface of the substrate. This LiF-rich SEI layer leads to a uniform distribution of the electric field on the substrate surface and enables uniform and dendrite-free Li deposition. Meanwhile the detrimental effect of HF is diminished due to the consumption of HF in the LiF formation process. Microscopic analysis reveals that the as-deposited dendrite-free Li films exhibit a self-aligned and highly-compacted Li nanorods structure which is consistent with their charming blue color or known as structure color. These findings clearly demonstrate a novel approach to control the nucleation and grow process of Li metal films using well-controlled trace-amount of water. They also shine the light on the effect of water on other electrodeposition processes.

  6. Mixed-Salt/Ester Electrolytes for Low-Temperature Li+ Cells

    NASA Technical Reports Server (NTRS)

    Smart, Marshall; Bugga, Ratnakumar

    2006-01-01

    Electrolytes comprising, variously, LiPF6 or LiPF6 plus LiBF4 dissolved at various concentrations in mixtures of alkyl carbonates and alkyl esters have been found to afford improved low-temperature performance in rechargeable lithium-ion electrochemical cells. These and other electrolytes have been investigated in a continuing effort to extend the lower limit of operating temperatures of such cells. This research at earlier stages, and the underlying physical and chemical principles, were reported in numerous previous NASA Tech Briefs articles, the most recent being Ester-Based Electrolytes for Low-Temperature Li-Ion Cells (NPO-41097), NASA Tech Briefs, Vol. 29, No. 12 (December 2005), page 59. The ingredients of the solvent mixtures include ethylene carbonate (EC), ethyl methyl carbonate (EMC), methyl butyrate (MB), and methyl propionate (MP). The electrolytes were placed in Li-ion cells containing carbon anodes and LiNi0.8Co0.2O2 cathodes, and the electrical performances of the cells were measured over a range of temperatures down to 60 C. The electrolytes that yielded the best low-temperature performances were found to consist, variously, of 1.0 M LiPF6 + 0.4 M LiBF4 or 1.4 LiPF6 in 1EC + 1EMC + 8MP or 1EC + 1EMC + 8MB, where the concentrations of the salts are given in molar units and the proportions of the solvents are by relative volume.

  7. Reoxidation of uranium metal immersed in a Li2O-LiCl molten salt after electrolytic reduction of uranium oxide

    NASA Astrophysics Data System (ADS)

    Choi, Eun-Young; Jeon, Min Ku; Lee, Jeong; Kim, Sung-Wook; Lee, Sang Kwon; Lee, Sung-Jai; Heo, Dong Hyun; Kang, Hyun Woo; Jeon, Sang-Chae; Hur, Jin-Mok

    2017-03-01

    We present our findings that uranium (U) metal prepared by using the electrolytic reduction process for U oxide (UO2) in a Li2O-LiCl salt can be reoxidized into UO2 through the reaction between the U metal and Li2O in LiCl. Two salt types were used for immersion of the U metal: one was the salt used for electrolytic reduction, and the other was applied to the unused LiCl salts with various concentrations of Li2O and Li metal. Our results revealed that the degree of reoxidation increases with the increasing Li2O concentration in LiCl and that the presence of the Li metal in LiCl suppresses the reoxidation of the U metal.

  8. Temperature dependence of nonlinear optical properties in Li doped nano-carbon bowl material

    NASA Astrophysics Data System (ADS)

    Li, Wei-qi; Zhou, Xin; Chang, Ying; Quan Tian, Wei; Sun, Xiu-Dong

    2013-04-01

    The mechanism for change of nonlinear optical (NLO) properties with temperature is proposed for a nonlinear optical material, Li doped curved nano-carbon bowl. Four stable conformations of Li doped corannulene were located and their electronic properties were investigated in detail. The NLO response of those Li doped conformations varies with relative position of doping agent on the curved carbon surface of corannulene. Conversion among those Li doped conformations, which could be controlled by temperature, changes the NLO response of bulk material. Thus, conformation change of alkali metal doped carbon nano-material with temperature rationalizes the variation of NLO properties of those materials.

  9. Synthesis and characterisation of copper doped Ca-Li hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Pogosova, M. A.; Kazin, P. E.; Tretyakov, Y. D.

    2012-08-01

    Hydroxyapapites M10(PO4)6(OH)2 (MHAP), where M is an alkaline earth metal, colored by incorporation of copper ions substituting protons, were discovered recently [1]. Now this kind of apatite-type materials can be used as inorganic pigments. Until now blue (BaHAP), violet (SrHAP) and wine-red (CaHAP) colors were achieved by the copper ions introduction [2]. The task of the present work was to study possibility of further M-ion substitution to affect the color and shift it toward the red-orange tint. Polycrystalline hydroxyapatites Ca10-xLix+yCuz(PO4)6O2H2-y-z-σ (Ca-LiHAP) were synthesized by solid state reaction at 1150 °C (ceramic method) and studied by X-ray powder diffraction (XRD), infrared absorption and diffuse-reflectance spectroscopy. Refinement of the X-ray diffraction patterns by the Rietveld method shows that CaHAP unit cell parameters are a little bigger, than Ca-LiHAP ones. Small difference between unit cell parameters could be caused by two ways of the Li+ ions introduction: (1) at the Ca2+ sites (Ca-Li substitution); (2) into hexagonal channels (H-Li substitution). The Li ions doping changes the color of the copper doped CaHAP from wine-red to pink and red.

  10. Interaction of High Flash Point Electrolytes and PE-Based Separators for Li-Ion Batteries.

    PubMed

    Hofmann, Andreas; Kaufmann, Christoph; Müller, Marcus; Hanemann, Thomas

    2015-08-27

    In this study, promising electrolytes for use in Li-ion batteries are studied in terms of interacting and wetting polyethylene (PE) and particle-coated PE separators. The electrolytes are characterized according to their physicochemical properties, where the flow characteristics and the surface tension are of particular interest for electrolyte-separator interactions. The viscosity of the electrolytes is determined to be in a range of η = 4-400 mPa∙s and surface tension is finely graduated in a range of γL = 23.3-38.1 mN∙m(-1). It is verified that the technique of drop shape analysis can only be used in a limited matter to prove the interaction, uptake and penetration of electrolytes by separators. Cell testing of Li|NMC half cells reveals that those cell results cannot be inevitably deduced from physicochemical electrolyte properties as well as contact angle analysis. On the other hand, techniques are more suitable which detect liquid penetration into the interior of the separator. It is expected that the results can help fundamental researchers as well as users of novel electrolytes in current-day Li-ion battery technologies for developing and using novel material combinations.

  11. Anode-electrolyte double-layer of Li-ion batteries: Structure and Li-ion intercalation

    NASA Astrophysics Data System (ADS)

    Wipf, David O.; Abou Hamad, Ibrahim; Rikvold, Per Arne; Novotny, Mark A.

    2011-03-01

    The electrochemical double-layer structure plays an important role in Li-ion intercalation during charging of Li-ion batteries with a graphite anode. In our recent Molecular Dynamics studies of a proposed accelerated charging method [I. Abou Hamad~et al., Phys. Chem. Chem. Phys. 12, 2740-2743 (2010)], we notice that ethylene carbonate and propylene carbonate molecules of the electrolyte assemble themselves in a preferred orientation at the electrode-electrolyte interface. On the other hand, they are randomly oriented in the bulk electrolyte. We show that the structure of the double layer is affected by the intercalating Li-ion: while the dipole moments of double-layer molecules far from the intercalating Li-ion point toward the graphite sheets of the anode, they point away from the intercalation site close to the intercalating Li-ion. This observation should contribute to a better understanding of the intercalation process. This work was supported in part by NSF Grant No. DMR-0802288.

  12. Impact of electrolyte solvent and additive choices on high voltage Li-ion pouch cells

    NASA Astrophysics Data System (ADS)

    Xia, Jian; Nelson, K. J.; Lu, Zhonghua; Dahn, J. R.

    2016-10-01

    The effects that various electrolyte solvents and electrolyte additives had on both LaPO4-coated LiNi0.4Mn0.4Co0.2O2 and uncoated LiNi0.4Mn0.4Co0.2O2/graphite pouch cells were studied using automated storage, electrochemical impedance spectroscopy, gas production and long-term cycling experiments. Storage experiments showed that the voltage drop during storage at 4.3 or 4.4 V for both coated and uncoated cells was very similar for the same electrolyte choice. At 4.5 V or above, the LaPO4-coated cells had a significantly smaller voltage drop than the uncoated cells except when fluorinated electrolytes were used. Automated charge discharge cycling/impedance spectroscopy testing of cells held at 4.5 V for 24 h every cycle showed that all cells containing ethylene carbonate:ethyl methyl carbonate electrolyte or sulfolane:ethyl methyl carbonate electrolyte exhibited severe capacity fade. By contrast, cells containing fluorinated electrolytes had the best capacity retention and smallest impedance growth during these aggressive cycling/hold tests. Long-term cycling experiments to 4.5 V confirmed that cells containing fluorinated electrolyte had the best cycling performance in the uncoated LiNi0.4Mn0.4Co0.2O2/graphite cells while cells containing sulfolane:ethyl methyl carbonate electrolyte had the best cycling performance in coated LiNi0.4Mn0.4Co0.2O2/graphite cells.

  13. Improved Li-TiS2 cell cycling in ether-based electrolytes with synergistic additives

    NASA Technical Reports Server (NTRS)

    Shen, D. H.; Subbarao, S.; Deligiannis, F.; Huang, C.-K.; Halpert, G.; Dominey, L.; Koch, V. R.; Goldman, J.

    1991-01-01

    Results of the application of 2-MeF and KOH additives to improve the lithium stability in THF, dioxolane, and THF/2-MeTHF solvent-based electrolytes are presented. The stability of these electrolytes with and without additives is evaluated by microcalorimetry and AC impedance spectroscopy. A novel method, cathode turnover number, is proposed to represent the electrolyte performance in a given system. The lithium cycling efficiency and cathode turnover number of the electrolytes are calculated from the cycle life data in experimental Li-TiS2 cells. Overall, THF/2-MeTHF electrolyte containing 2-MeF and/or KOH exhibited higher stability, lithium cycling efficiency, and cathode turnover number compared to THF and dioxolane electrolytes with and without additives.

  14. Low-EC-Content Electrolytes for Low-Temperature Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, Marshall; Bugga, Ratnakumar; Surampudi, Subbarao

    2003-01-01

    Electrolytes comprising LiPF6 dissolved at a concentration of 1.0 M in three different mixtures of alkyl carbonates have been found well suited for use in rechargeable lithium-ion electrochemical cells at low temperatures. These and other electrolytes have been investigated in continuing research directed toward extending the lower limit of practical operating temperatures of Li-ion cells down to -60 C. This research at earlier stages was reported in numerous previous NASA Tech Briefs articles, the three most recent being "Ethyl Methyl Carbonate as a Cosolvent for Lithium-Ion Cells" (NPO-20605), Vol. 25, Low-EC-Content Electrolytes for Low-Temperature Li-Ion Cells No. 6 (June 2001), page 53; "Alkyl Pyrocarbonate Electrolyte Additives for Li-Ion Cells" (NPO-20775), Vol. 26, No. 5 (May 2002), page 37; and "Fluorinated Alkyl Carbonates as Cosolvents in Li-Ion Cells (NPO-21076), Vol. 26, No. 5 (May 2002), page 38. The present solvent mixtures, in terms of volume proportions of their ingredients, are 1 ethylene carbonate (EC) + 1 diethyl carbonate (DEC) + 1 dimethyl carbonate (DMC) + 3 ethyl methyl carbonate (EMC); 3EC + 3DMC + 14EMC; and 1EC + 1DEC + 1DMC + 4EMC. Relative to similar mixtures reported previously, the present mixtures, which contain smaller proportions of EC, have been found to afford better performance in experimental Li-ion cells at temperatures < -20 C.

  15. Electrochemical performance of nanostructured spinel LiMn 2O 4 in different aqueous electrolytes

    NASA Astrophysics Data System (ADS)

    Tian, Lei; Yuan, Anbao

    A nanostructured spinel LiMn 2O 4 electrode material was prepared via a room-temperature solid-state grinding reaction route starting with hydrated lithium acetate (LiAc·2H 2O), manganese acetate (MnAc 2·4H 2O) and citric acid (C 6H 8O 7·H 2O) raw materials, followed by calcination of the precursor at 500 °C. The material was characterized by X-ray diffraction (XRD) and transmission electron microscope techniques. The electrochemical performance of the LiMn 2O 4 electrodes in 2 M Li 2SO 4, 1 M LiNO 3, 5 M LiNO 3 and 9 M LiNO 3 aqueous electrolytes was studied using cyclic voltammetry, ac impedance and galvanostatic charge/discharge methods. The LiMn 2O 4 electrode in 5 M LiNO 3 electrolyte exhibited good electrochemical performance in terms of specific capacity, rate dischargeability and charge/discharge cyclability, as evidenced by the charge/discharge results.

  16. High-performance gel electrolytes with tetra-armed polymer network for Li ion batteries

    NASA Astrophysics Data System (ADS)

    Hazama, Taisuke; Fujii, Kenta; Sakai, Takamasa; Aoki, Masahiro; Mimura, Hideyuki; Eguchi, Hisao; Todorov, Yanko; Yoshimoto, Nobuko; Morita, Masayuki

    2015-07-01

    An organo gel with only 6 wt % tetra-armed poly(ethylene glycol), TetraPEG, was prepared and applied as a novel gel electrolyte for Li ion batteries (LIBs). The TetraPEG gel electrolyte containing 1.0 M LiPF6 in binary or ternary mixtures, i.e., EC + DEC and EC + DEC + TFEP (EC: ethylene carbonate, DEC: diethyl carbonate and TFEP: tris(2,2,2-trifluoroethyl)phosphate showed high ionic conductivity required for the use in LIB systems. The TetraPEG gel based on ternary EC + DEC + TFEP system acts as a nonflammable gel electrolyte at the TFEP content higher than 20 vol%. In cyclic voltammetry and charge/discharge cycling tests, the TetraPEG gel electrolytes showed good reversibility for a graphite negative electrode.

  17. On the chemical stability of post-lithiated garnet Al-stabilized Li7La3Zr2O12 solid state electrolyte thin films

    NASA Astrophysics Data System (ADS)

    Rawlence, Michael; Garbayo, Inigo; Buecheler, Stephan; Rupp, J. L. M.

    2016-08-01

    Garnet-based Al-doped Li7La3Zr2O12 has the potential to be used as a solid state electrolyte for future lithium microbattery architectures, due to its relatively high Li+ conductivity and stability against Li. Through this work, a model experiment is presented in which the effect of post-lithiation on phase formation and chemical stability is studied for pulsed laser deposited Al-doped Li7La3Zr2O12 thin films on MgO substrates. We report the implications of the newly suggested post-lithiation route for films with thicknesses between 90 and 380 nm. The phase changes from cubic, to a mix of cubic and tetragonal Li7La3Zr2O12, to a cubic Li7La3Zr2O12 and La2Zr2O7 containing film is accompanied by a reduction in the degree of de-wetting as the thickness increases. This study reveals that the thicker, dense, and continuous films remain predominantly in a mixed phase containing cubic Li7La3Zr2O12 and the lithium free La2Zr2O7 phase whereas the thinner, de-wetted films exhibit improved lithium incorporation resulting in the absence of the lithium free phase. For tuning the electrical conductivity and effective use of these structures in future batteries, understanding this material system is of great importance as the chemical stability of the cubic Li7La3Zr2O12 phase in the thin film system will control its effective use. We report a conductivity of 1.2 × 10-3 S cm-1 at 325 °C for a 380 nm thick solid state electrolyte film on MgO for potential operation in future all solid state battery assemblies.Garnet-based Al-doped Li7La3Zr2O12 has the potential to be used as a solid state electrolyte for future lithium microbattery architectures, due to its relatively high Li+ conductivity and stability against Li. Through this work, a model experiment is presented in which the effect of post-lithiation on phase formation and chemical stability is studied for pulsed laser deposited Al-doped Li7La3Zr2O12 thin films on MgO substrates. We report the implications of the newly

  18. Deciphering the multi-step degradation mechanisms of carbonate-based electrolyte in Li batteries

    NASA Astrophysics Data System (ADS)

    Gachot, Gregory; Grugeon, Sylvie; Armand, Michel; Pilard, Serge; Guenot, Pierre; Tarascon, Jean-Marie; Laruelle, Stephane

    Electrolytes are crucial to the safety and long life of Li-ion batteries, however, the understanding of their degradation mechanisms is still sketchy. Here we report on the nature and formation of organic/inorganic degradation products generated at low potential in a lithium-based cell using cyclic and linear carbonate-based electrolyte mixtures. The global formation mechanism of ethylene oxide oligomers produced from EC/DMC (1/1 w/w)-LiPF 6 salt (1 M) electrolyte decomposition is proposed then mimicked via chemical tests. Each intermediary product structure/formula/composition is identified by means of combined NMR, FTIR and high resolution mass spectrometry (ESI-HRMS) analysis. The key role played by lithium methoxide as initiator of the electrolyte degradation is evidenced, but more importantly we isolated for the first time lithium methyl carbonate as a side product of the ethylene oxide oligomers chemical formation. The same degradation mechanism was found to hold on for another cyclic and linear carbonate-based electrolyte such as EC/DEC (1/1 w/w)-LiPF 6 salt (1 M). Such findings have important implications in the choice of chemical additives for developing highly performing electrolytes.

  19. Li-Ion Electrolytes with Improved Safety and Tolerance to High-Voltage Systems

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Bugga, Ratnakumar V.; Prakash, Surya; Krause, Frederick C.

    2013-01-01

    Given that lithium-ion (Li-ion) technology is the most viable rechargeable energy storage device for near-term applications, effort has been devoted to improving the safety characteristics of this system. Therefore, extensive effort has been devoted to developing nonflammable electrolytes to reduce the flammability of the cells/battery. A number of promising electrolytes have been developed incorporating flame-retardant additives, and have been shown to have good performance in a number of systems. However, these electrolyte formulations did not perform well when utilizing carbonaceous anodes with the high-voltage materials. Thus, further development was required to improve the compatibility. A number of Li-ion battery electrolyte formulations containing a flame-retardant additive [i.e., triphenyl phosphate (TPP)] were developed and demonstrated in high-voltage systems. These electrolytes include: (1) formulations that incorporate varying concentrations of the flame-retardant additive (from 5 to 15%), (2) the use of mono-fluoroethylene carbonate (FEC) as a co-solvent, and (3) the use of LiBOB as an electrolyte additive intended to improve the compatibility with high-voltage systems. Thus, improved safety has been provided without loss of performance in the high-voltage, high-energy system.

  20. Interaction of High Flash Point Electrolytes and PE-Based Separators for Li-Ion Batteries

    PubMed Central

    Hofmann, Andreas; Kaufmann, Christoph; Müller, Marcus; Hanemann, Thomas

    2015-01-01

    In this study, promising electrolytes for use in Li-ion batteries are studied in terms of interacting and wetting polyethylene (PE) and particle-coated PE separators. The electrolytes are characterized according to their physicochemical properties, where the flow characteristics and the surface tension are of particular interest for electrolyte–separator interactions. The viscosity of the electrolytes is determined to be in a range of η = 4–400 mPa∙s and surface tension is finely graduated in a range of γL = 23.3–38.1 mN∙m−1. It is verified that the technique of drop shape analysis can only be used in a limited matter to prove the interaction, uptake and penetration of electrolytes by separators. Cell testing of Li|NMC half cells reveals that those cell results cannot be inevitably deduced from physicochemical electrolyte properties as well as contact angle analysis. On the other hand, techniques are more suitable which detect liquid penetration into the interior of the separator. It is expected that the results can help fundamental researchers as well as users of novel electrolytes in current-day Li-ion battery technologies for developing and using novel material combinations. PMID:26343636

  1. LiMn 2O 4 cathode doped with excess lithium and synthesized by co-precipitation for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Chan, H. W.; Duh, J. G.; Sheen, S. R.

    LiMn 2O 4 exhibits lower cost, acceptable environmental characteristics, and better safety properties than other positive-electrode (cathode) materials for lithium-ion batteries. In this study, excess Li doped Li 1+ xMn 2O 4 is synthesized by a well-mixed co-precipitation method with LiOH utilized as both the reactant and co-precipitation agent. The precursor is calcined for various heating times and temperatures to form a fine powder of a single spinel phase with different particle sizes, size distributions, and morphology. The minimum heating temperature is around 400 °C. For short heating periods, Mn 2O 3 impurity is observed, but disappears after longer heating times. The average particle size is in the range 2-8 μm for powders calcined between 700 and 870 °C. The lattice parameter increases with increase in heating temperature. The electrochemical behavior of LiMn 2O 4 powder is examined by using test cells which consist of a cathode, a metallic lithium anode, and an electrolyte of 1 M LiPF 6 in a 1:1 (volume ratio) mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC). Cells with cathodes of LiMn 2O 4, Li 1.08Mn 2O 4 and Li 1.1Mn 2O 4 give a capacity of 85, 109 and 126 mAh g -1, respectively. The introduction of excess Li in LiMn 2O 4 apparently increases the capacity, and decreases significantly the rate of capacity degradation on charge-discharge cycling.

  2. Mesoscopic Framework Enables Facile Ionic Transport in Solid Electrolytes for Li Batteries

    SciTech Connect

    Ma, Cheng; Cheng, Yongqiang; Chen, Kai; Li, Juchuan; Sumpter, Bobby G.; Nan, Ce-Wen; More, Karren L.; Dudney, Nancy J.; Chi, Miaofang

    2016-03-29

    In Li-ion-conducting solid electrolytes can simultaneously overcome two grand challenges for Li-ion batteries: the severe safety concerns that limit the large-scale application and the poor electrolyte stability that forbids the use of high-voltage cathodes. Nevertheless, the ionic conductivity of solid electrolytes is typically low, compromising the battery performances. Precisely determining the ionic transport mechanism(s) is a prerequisite for the rational design of highly conductive solid electrolytes. For decades, the research on this subject has primarily focused on the atomic and microscopic scales, where the main features of interest are unit cells and microstructures, respectively. We show that the largely overlooked mesoscopic scale lying between these extremes could be the key to fast ionic conduction. In a prototype system, (Li0.33La0.56)TiO3, a mesoscopic framework is revealed for the first time by state-of-the-art scanning transmission electron microscopy. Corroborated by theoretical calculations and impedance measurements, it is demonstrated that such a unique configuration maximizes the number of percolation directions and thus most effectively improves the ionic conductivity. Finally, this discovery reconciles the long-standing structure–property inconsistency in (Li0.33La0.56)TiO3 and also identifies mesoscopic ordering as a promising general strategy for optimizing Li+ conduction.

  3. Mesoscopic Framework Enables Facile Ionic Transport in Solid Electrolytes for Li Batteries

    DOE PAGES

    Ma, Cheng; Cheng, Yongqiang; Chen, Kai; ...

    2016-03-29

    In Li-ion-conducting solid electrolytes can simultaneously overcome two grand challenges for Li-ion batteries: the severe safety concerns that limit the large-scale application and the poor electrolyte stability that forbids the use of high-voltage cathodes. Nevertheless, the ionic conductivity of solid electrolytes is typically low, compromising the battery performances. Precisely determining the ionic transport mechanism(s) is a prerequisite for the rational design of highly conductive solid electrolytes. For decades, the research on this subject has primarily focused on the atomic and microscopic scales, where the main features of interest are unit cells and microstructures, respectively. We show that the largely overlookedmore » mesoscopic scale lying between these extremes could be the key to fast ionic conduction. In a prototype system, (Li0.33La0.56)TiO3, a mesoscopic framework is revealed for the first time by state-of-the-art scanning transmission electron microscopy. Corroborated by theoretical calculations and impedance measurements, it is demonstrated that such a unique configuration maximizes the number of percolation directions and thus most effectively improves the ionic conductivity. Finally, this discovery reconciles the long-standing structure–property inconsistency in (Li0.33La0.56)TiO3 and also identifies mesoscopic ordering as a promising general strategy for optimizing Li+ conduction.« less

  4. Aging of the LiFePO 4 positive electrode interface in electrolyte

    NASA Astrophysics Data System (ADS)

    Dupré, Nicolas; Martin, Jean-Frédéric; Degryse, Jeremy; Fernandez, Vincent; Soudan, Patrick; Guyomard, Dominique

    The evolution of lithium-containing species on the surface of grains of 500 nm LiFePO 4 and 100 nm carbon-coated LiFePO 4 materials during the aging process in LiPF 6 electrolyte has been followed using coupled 7Li MAS NMR, EIS (Electrochemical Impedance Spectroscopy) and XPS for materials synthesized with and without carbon coating. LiFePO 4 undergoes surface reactivity upon immersion in classical LiPF 6 electrolyte, although its open circuit voltage (∼3.2 V) lies in the thermodynamical stability voltage range. The evolution of the NMR signal shows that the reaction of formation of the interphase is very slow as no evidence of passivation could be found even after 1 month of contact with the electrolyte. 7Li MAS NMR combined with XPS indicates that carbon coating has a strong protective role towards formation of surface species on the material and hinders iron dissolution at elevated temperature. Coupled NMR, EIS and XPS experiments showed that the surface of the material grains is not covered by an homogenous layer. Increasing the storage temperature from 25 °C to 55 °C promotes the formation of organic species on the surface, most probably covering inorganic species such as LiF, Li xPF y and LiPO yF z. No evidence of the formation of a resistive film is deduced from the evolution of EIS measurements. The interphase growth can accelerate the degradation of the electrochemical performance, leading to a loss of electrical contact within the electrode.

  5. Electrolyte Solvation and Ionic Association. V. Acetonitrile-Lithium Bis(fluorosulfonyl)imide (LiFSI) Mixtures

    SciTech Connect

    Han, Sang D.; Borodin, Oleg; Seo, D. M.; Zhou, Zhi B.; Henderson, Wesley A.

    2014-09-30

    Electrolytes with the salt lithium bis(fluorosulfonyl)imide (LiFSI) have been evaluated relative to comparable electrolytes with other lithium salts. Acetonitrile (AN) has been used as a model electrolyte solvent. The information obtained from the thermal phase behavior, solvation/ionic association interactions, quantum chemical (QC) calculations and molecular dynamics (MD) simulations (with an APPLE&P many-body polarizable force field for the LiFSI salt) of the (AN)n-LiFSI mixtures provides detailed insight into the coordination interactions of the FSI- anions and the wide variability noted in the electrolyte transport property (i.e., viscosity and ionic conductivity).

  6. Promoting solution phase discharge in Li-O2 batteries containing weakly solvating electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Gao, Xiangwen; Chen, Yuhui; Johnson, Lee; Bruce, Peter G.

    2016-08-01

    On discharge, the Li-O2 battery can form a Li2O2 film on the cathode surface, leading to low capacities, low rates and early cell death, or it can form Li2O2 particles in solution, leading to high capacities at relatively high rates and avoiding early cell death. Achieving discharge in solution is important and may be encouraged by the use of high donor or acceptor number solvents or salts that dissolve the LiO2 intermediate involved in the formation of Li2O2. However, the characteristics that make high donor or acceptor number solvents good (for example, high polarity) result in them being unstable towards LiO2 or Li2O2. Here we demonstrate that introduction of the additive 2,5-di-tert-butyl-1,4-benzoquinone (DBBQ) promotes solution phase formation of Li2O2 in low-polarity and weakly solvating electrolyte solutions. Importantly, it does so while simultaneously suppressing direct reduction to Li2O2 on the cathode surface, which would otherwise lead to Li2O2 film growth and premature cell death. It also halves the overpotential during discharge, increases the capacity 80- to 100-fold and enables rates >1 mA cmareal-2 for cathodes with capacities of >4 mAh cmareal-2. The DBBQ additive operates by a new mechanism that avoids the reactive LiO2 intermediate in solution.

  7. Lithium-sulfur batteries based on nitrogen-doped carbon and ionic liquid electrolyte

    SciTech Connect

    Sun, Xiao-Guang; Wang, Xiqing; Mayes, Richard T; Dai, Sheng

    2012-01-01

    Nitrogen-doped mesoporous carbon (NC) and sulfur were used to prepare an NC/S composite cathode, which was evaluated in an ionic liquid electrolyte of 0.5 M lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) in methylpropylpyrrolidinium bis(trifluoromethane sulfonyl)imide (MPPY.TFSI) by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and cycle testing. To facilitate the comparison, a C/S composite based on activated carbon (AC) without nitrogen doping was also fabricated under the same conditions as those for the NC/S composite. Compared with the AC/S composite, the NC/S composite showed enhanced activity toward sulfur reduction, as evidenced by the early onset sulfur reduction potential, higher redox current density in the CV test, and faster charge transfer kinetics as indicated by EIS measurement. At room temperature under a current density of 84 mA g-1 (C/20), the battery based on the NC/S composite exhibited higher discharge potential and an initial capacity of 1420 mAh g-1 whereas that based on the AC/S composite showed lower discharge potential and an initial capacity of 1120 mAh g-1. Both batteries showed similar capacity fading with cycling due to the intrinsic polysulfide solubility and the polysulfide shuttle mechanism; the capacity fading can be improved by further modification of the cathode.

  8. High-rate Li4Ti5O12/N-doped reduced graphene oxide composite using cyanamide both as nanospacer and a nitrogen doping source

    NASA Astrophysics Data System (ADS)

    Jeong, Jun Hui; Kim, Myeong-Seong; Kim, Young-Hwan; Roh, Kwang Chul; Kim, Kwang-Bum

    2016-12-01

    A Li4Ti5O12(LTO)/N-doped reduced graphene oxide (RGO) composite is proposed using dual functional nitrogen doping source to prevent RGO restacking and achieve uniform nitrogen doping on RGO sheets to increase the rate performance of high-rate lithium ion batteries. The pore structure (both meso- and macro pores) is developed when RGO restacking is prevented, facilitating electrolyte ion diffusion to active sites with lower resistance. Uniform nitrogen doping on RGO sheets with high nitrogen contents provides additional free electrons to the sheets, resulting in increased electronic conductivity. Cyanamide is used as the nitrogen doping source for the N-doped RGO as well as a nanospacer between the RGO sheets. In the composite, the nitrogen content of the RGO sheets is 2.3 wt%, which increases the electronic conductivity of the composite to 1.60 S cm-1. The specific surface area of the composite is increased to 35.8 m2 g-1. Thus, the composite structure with the N-doped RGO sheets and porous secondary particles has high electrical conductivity and high ion accessibility. The LTO/N-doped RGO composite demonstrates excellent electrochemical performance with a low resistance of 48.4 Ω, a high specific capacity of 117.8 mAh g-1 at 30 C, and good cycle stability.

  9. Preperation and electrochemical characterization of Sm and Gd co-doped ceria/carbonate composite electrolytes for IT-SOFC applications

    NASA Astrophysics Data System (ADS)

    Dikmen, Sibel; Ozsakarya, Rabia; Dikmen, Erdal

    2014-03-01

    Sm and Gd co-doped ceria based composite electrolytes were prepared by mixing nanosized powders of Ce0.8Sm0.1Gd0.1O2-δ (SGDC) and alkaline carbonates (Na-Li)2CO3, (Li-K)2CO3,and(Na-K)2CO3 at a weight ratio of 4:1. Structure of the samples was characterized by powder X-ray diffraction. The microstructure and morphology were examined by SEM. Impedance spectroscopy was used to perform electrochemical characterization. The conductivities of the samples increase as the temperature increases and for the composite electrolytes SGDC(Na-Li)2CO3,andSGDC(Li-K)2CO3, there is a sharp increase in conductivity at around 475 and 450oC, respectively. This sudden change in the conductivity refers to superionic phase transition in the interfaces between SGDC phase and salt phase. The single cell power density reached a maximum of 1056, 826, and 565 mWcm-2 for SGDC/ (Na-Li)2CO3, SGDC/(Li-K)2CO3,andSGDC/(Na-K)2CO3 as the electrolytes, respectively. This work was funded by TUB?TAK 106T536, SDU-BAP 3231-YL1-12.

  10. Lithium Bis(fluorosulfonyl)imide/Poly(ethylene oxide) Polymer Electrolyte for All Solid-State Li-S Cell.

    PubMed

    Judez, Xabier; Zhang, Heng; Li, Chunmei; González-Marcos, José Antonio; Zhou, Zhi-Bin; Armand, Michel; Rodriguez-Martinez, Lide Mercedes

    2017-04-13

    Solid polymer electrolytes (SPEs) comprising lithium bis(fluorosulfonyl)imide (Li[N(SO2F)2], LiFSI) and poly(ethylene oxide) (PEO) have been studied as electrolyte material and binder for the Li-S polymer cell. The LiFSI-based Li-S all solid polymer cell can deliver high specific discharge capacity of 800 mAh gsulfur-1 (i.e., 320 mAh gcathode-1), high areal capacity of 0.5 mAh cm-2 and relatively good rate capability. The cycling performances of Li-S polymer cell with LiFSI are significantly improved compared to with those with conventional LiTFSI (Li[N(SO2CF3)2]) salt in the polymer membrane, due to the improved stability of the Li anode/electrolyte interphases formed in the LiFSI-based SPEs. These results suggest that the LiFSI-based SPEs are attractive electrolyte materials for solid-state Li-S batteries.

  11. Oxygen substitution effects in Li10GeP2S12 solid electrolyte

    NASA Astrophysics Data System (ADS)

    Sun, Yulong; Suzuki, Kota; Hara, Kosuke; Hori, Satoshi; Yano, Taka-aki; Hara, Masahiko; Hirayama, Masaaki; Kanno, Ryoji

    2016-08-01

    For the lithium super-ionic conductor Li10GeP2S12, the partial substitution of sulfur by oxygen is achieved via a solid-state reaction. The solid-solution range of oxygen is found to be 0 ≤ x < 0.9 in Li10GeP2S12-xOx. Structure refinements using synchrotron X-ray diffraction data confirm the preference for oxygen substitution in the PS4 tetrahedra. The local structural change in the P(S/O)4 tetrahedra upon substitution is also indicated by Raman spectroscopy. Ionic conduction properties are maintained even after the oxygen substitution in Li10GeP2S12; the ionic conductivity of Li10GeP2S12-xOx (0.3 ≤ x ≤ 0.6) ranges from 1.03 × 10-2 to 8.43 × 10-3 S cm-1 at 298 K. No redox current is observed by cyclic voltammetry from nearly 0 to 10 V versus Li/Li+ except for that due to the lithium deposition/dissolution reactions. All-solid-state batteries using Li10GeP2S12-xOx (x = 0.3 and 0.6) as solid electrolytes with Li metal anodes show discharge capacities exceeding 100 mAh g-1 and better cycling performance compared to batteries using the original Li10GeP2S12. The partial substitution of oxygen for sulfur in Li10GeP2S12 affords a novel solid electrolyte, Li10GeP2S12-xOx, with high conductive properties and electrochemical stability.

  12. Performance of Low Temperature Electrolytes in Experimental and Prototype Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Whitcanack, L. D.

    2007-01-01

    Due to their attractive properties and proven success, Li-ion batteries have become identified as the battery chemistry of choice for a number of future NASA missions. A number of these applications would be greatly benefited by improved performance of Li-ion technology over a wider operating temperature range, especially at low temperatures, such as future ESMD missions. In many cases, these technology improvements may be mission enabling, and at the very least mission enhancing. In addition to aerospace applications, the DoE has interest in developing advanced Li-ion batteries that can operate over a wide temperature range to enable terrestrial HEV applications. Thus, our focus at JPL in recent years has been to extend the operating temperature range of Li-ion batteries, especially at low temperatures. To accomplish this, the main focus of the research has been devoted to developing improved lithium-ion conducting electrolytes. In the present paper, we would like to present some of the results we have obtained with ethylene carbonate-based electrolytes optimized for low temperature in experimental MCMB-LiNixCo1_x0 2 cells. In addition to obtaining discharge and charge rate performance data at various temperatures, electrochemical measurements were performed on individual electrodes (made possible by the incorporation of Li reference electrodes), including EIS, linear polarization and Tafel polarization measurements. The combination of techniques enables the elucidation of various trends associated with electrolyte composition. In addition to investigating the behavior in experimental cells, the performance of many promising low temperature electrolytes was demonstrated in large capacity, aerospace quality Li-ion prototype cells. These cells were subjected to a number of performance tests, including discharge rate characterization, charge rate characterization, cycle life performance at various temperatures, and power characterization tests.

  13. Solvate Structures and Computational/Spectroscopic Characterization of LiBF4 Electrolytes

    SciTech Connect

    Seo, D. M.; Boyle, Paul D.; Allen, Joshua L.; Han, Sang D.; Jonsson, Erlendur; Johansson, Patrik; Henderson, Wesley A.

    2014-07-21

    Crystal structures have been determined for both LiBF4 and HBF4 solvates—(acetonitrile)2:LiBF4, (ethylene glycol diethyl ether)1:LiBF4, (diethylene glycol diethyl ether)1:LiBF4, (tetrahydrofuran)1:LiBF4, (methyl methoxyacetate)1:LiBF4, (suc-cinonitrile)1:LiBF4, (N,N,N',N",N"-pentamethyldiethylenetriamine)1:HBF4, (N,N,N',N'-tetramethylethylenediamine)3/2:HBF4 and (phenanthroline)2:HBF4. These, as well as other known LiBF4 solvate structures, have been characterized by Raman vibrational spectroscopy to unambiguously assign the anion Raman band positions to specific forms of BF4-...Li+ cation coordination. In addition, complementary DFT calculations of BF4-...Li+ cation complexes have provided additional insight into the challenges associated with accurately interpreting the anion interactions from experimental Raman spectra. This information provides a crucial tool for the characterization of the ionic association interactions within electrolytes.

  14. Conductivity and optical band gaps of polyethylene oxide doped with Li{sub 2}SO{sub 4} salt

    SciTech Connect

    Chapi, Sharanappa Raghu, S. Subramanya, K. Archana, K. Mini, V. Devendrappa, H.

    2014-04-24

    The conductivity and optical properties of Li{sub 2}SO{sub 4} doped polyethylene oxide (PEO) films were studied. The polymer electrolyte films are prepared using solution casting technique. The material phase change was confirmed by X-ray diffraction (XRD) technique. Optical absorption study was conducted using UV- Vis. Spectroscopy in the wavelength range 190–1100nm on pure and doped PEO films. The direct and indirect optical band gaps were found decreased from 5.81–4.51eV and 4.84–3.43eV respectively with increasing the Li{sub 2}SO{sub 4}. The conductivity found to increases with increasing the dopant concentration due to strong hopping mechanism at room temperature.

  15. Ester-Based Electrolytes for Low-Temperature Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, Marshall; Bugga, Ratnakumar

    2005-01-01

    Electrolytes comprising LiPF6 dissolved at a concentration of 1.0 M in five different solvent mixtures of alkyl carbonates have been found to afford improved performance in rechargeable lithium-ion electrochemical cells at temperatures as low as -70 C. These and other electrolytes have been investigated in continuing research directed toward extending the lower limit of practical operating temperatures of Li-ion cells. This research at earlier stages, and the underlying physical and chemical principles, were reported in numerous previous NASA Tech Briefs articles, the most recent being Low-EC-Content Electrolytes for Low-Temperature Li-Ion Cells (NPO-30226), NASA Tech Briefs, Vol. 27, No. 1 (January 2003), page 46. The ingredients of the present solvent mixtures are ethylene carbonate (EC), ethyl methyl carbonate (EMC), methyl butyrate (MB), methyl propionate (MP), ethyl propionate (EP), ethyl butyrate (EB), and ethyl valerate (EV). In terms of volume proportions of these ingredients, the present solvent mixtures are 1EC + 1EMC + 8MB, 1EC + 1EMC + 8EB, 1EC + 1EMC + 8MP, 1EC + 1EMC + 8EV, and 1EC + 9EMC. These electrolytes were placed in Liion cells containing carbon anodes and LiNi0.8Co0.2O2 cathodes, and the low-temperature electrical performances of the cells were measured. The cells containing the MB and MP mixtures performed best.

  16. Estimation of energy density of Li-S batteries with liquid and solid electrolytes

    NASA Astrophysics Data System (ADS)

    Li, Chunmei; Zhang, Heng; Otaegui, Laida; Singh, Gurpreet; Armand, Michel; Rodriguez-Martinez, Lide M.

    2016-09-01

    With the exponential growth of technology in mobile devices and the rapid expansion of electric vehicles into the market, it appears that the energy density of the state-of-the-art Li-ion batteries (LIBs) cannot satisfy the practical requirements. Sulfur has been one of the best cathode material choices due to its high charge storage (1675 mAh g-1), natural abundance and easy accessibility. In this paper, calculations are performed for different cell design parameters such as the active material loading, the amount/thickness of electrolyte, the sulfur utilization, etc. to predict the energy density of Li-S cells based on liquid, polymeric and ceramic electrolytes. It demonstrates that Li-S battery is most likely to be competitive in gravimetric energy density, but not volumetric energy density, with current technology, when comparing with LIBs. Furthermore, the cells with polymer and thin ceramic electrolytes show promising potential in terms of high gravimetric energy density, especially the cells with the polymer electrolyte. This estimation study of Li-S energy density can be used as a good guidance for controlling the key design parameters in order to get desirable energy density at cell-level.

  17. New-concept Batteries Based on Aqueous Li+/Na+ Mixed-ion Electrolytes

    PubMed Central

    Chen, Liang; Gu, Qingwen; Zhou, Xufeng; Lee, Saixi; Xia, Yonggao; Liu, Zhaoping

    2013-01-01

    Rechargeable batteries made from low-cost and abundant materials operating in safe aqueous electrolytes are attractive for large-scale energy storage. Sodium-ion battery is considered as a potential alternative of current lithium-ion battery. As sodium-intercalation compounds suitable for aqueous batteries are limited, we adopt a novel concept of Li+/Na+ mixed-ion electrolytes to create two batteries (LiMn2O4/Na0.22MnO2 and Na0.44MnO2/TiP2O7), which relies on two electrochemical processes. One involves Li+ insertion/extraction reaction, and the other mainly relates to Na+ extraction/insertion reaction. Two batteries exhibit specific energy of 17 Wh kg−1 and 25 Wh kg−1 based on the total weight of active electrode materials, respectively. As well, aqueous LiMn2O4/Na0.22MnO2 battery is capable of separating Li+ and Na+ due to its specific mechanism unlike the traditional “rocking-chair” lithium-ion batteries. Hence, the Li+/Na+ mixed-ion batteries offer promising applications in energy storage and Li+/Na+ separation. PMID:23736113

  18. Li-Ion Cells Employing Electrolytes With Methyl Propionate and Ethyl Butyrate Co-Solvents

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Bugga, Ratnakumar V.

    2011-01-01

    Future NASA missions aimed at exploring Mars and the outer planets require rechargeable batteries that can operate at low temperatures to satisfy the requirements of such applications as landers, rovers, and penetrators. A number of terrestrial applications, such as hybrid electric vehicles (HEVs) and electric vehicles (EVs) also require energy storage devices that can operate over a wide temperature range (i.e., -40 to +70 C), while still providing high power capability and long life. Currently, the state-of-the-art lithium-ion system has been demonstrated to operate over a wide range of temperatures (-30 to +40 C); however, the rate capability at the lower temperatures is very poor. These limitations at very low temperatures are due to poor electrolyte conductivity, poor lithium intercalation kinetics over the electrode surface layers, and poor ionic diffusion in the electrode bulk. Two wide-operating-temperature-range electrolytes have been developed based on advances involving lithium hexafluorophosphate-based solutions in carbonate and carbonate + ester solvent blends, which have been further optimized in the context of the technology and targeted applications. The approaches employed include further optimization of electrolytes containing methyl propionate (MP) and ethyl butyrate (EB), which are effective co-solvents, to widen the operating temperature range beyond the baseline systems. Attention was focused on further optimizing ester-based electrolyte formulations that have exhibited the best performance at temperatures ranging from -60 to +60 C, with an emphasis upon improving the rate capability at -20 to -40 C. This was accomplished by increasing electrolyte salt concentration to 1.20M and increasing the ester content to 60 percent by volume to increase the ionic conductivity at low temperatures. Two JPL-developed electrolytes 1.20M LiPF6 in EC+EMC+MP (20:20:60 v/v %) and 1.20M LiPF6 in EC+EMC+EB (20:20:60 v/v %) operate effectively over a wide

  19. Li-air batteries having ether-based electrolytes

    DOEpatents

    Amine, Khalil; Curtiss, Larry A; Lu, Jun; Lau, Kah Chun; Zhang, Zhengcheng; Sun, Yang-Kook

    2015-03-03

    A lithium-air battery includes a cathode including a porous active carbon material, a separator, an anode including lithium, and an electrolyte including a lithium salt and polyalkylene glycol ether, where the porous active carbon material is free of a metal-based catalyst.

  20. Assessment of Various Low Temperature Electrolytes in Prototype Li-Ion Cells Developed for ESMD Applications

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Whitcanack, L. D.

    2008-01-01

    Due to their attractive properties and proven success, Li-ion batteries have become identified as the battery chemistry of choice for a number of future NASA missions. A number of these applications would be greatly benefited by improved performance of Li-ion technology over a wider operating temperature range, especially at low temperatures, such as future ESMD missions. In many cases, these technology improvements may be mission enabling, and at the very least mission enhancing. In addition to aerospace applications, the DoE has interest in developing advanced Li-ion batteries that can operate over a wide temperature range to enable terrestrial HEV applications. Thus, our focus at JPL in recent years has been to extend the operating temperature range of Li-ion batteries, especially at low temperatures. To accomplish this, the main focus of the research has been devoted to developing improved lithium-ion conducting electrolytes. In the present paper, we would like to present some of the results we have obtained with six different ethylene carbonate-based electrolytes optimized for low temperature. In addition to investigating the behavior in experimental cells initially, the performance of these promising low temperature electrolytes was demonstrated in large capacity, aerospace quality Li-ion prototype cells, manufactured by Yardney Technical Products and Saft America, Inc. These cells were subjected to a number of performance tests, including discharge rate characterization, charge rate characterization, cycle life performance at various temperatures, and power characterization tests.

  1. Effect of electrolyte water content on the anodic passivation of lithium in IM LiC104-propylene carbonate

    NASA Astrophysics Data System (ADS)

    James, S. D.; Nagao, A. R.

    1982-06-01

    This work deals with the effect of aqueous contamination on the anode passivation of Li in 1M LiC10 4-propylene carbonate. Passivation occurs more readily with increasing electrolyte water content. Preliminary evidence suggests that anodic passivation may be due to anodic enrichment and eventual precipitation of LiC10 4 in the superficial anolyte layer.

  2. Air-Stable, High-Conduction Solid Electrolytes of Arsenic-Substituted Li4SnS4

    SciTech Connect

    Sahu, Gayatri; Lin, Zhan; Li, Juchuan; Liu, Zengcai; Dudney, Nancy J; Liang, Chengdu

    2014-01-01

    Lithium-ion-conducting solid electrolytes show promise for enabling high-energy secondary battery chemistries and solving safety issues associated with conventional lithium batteries. Achieving the combination of high ionic conductivity and outstanding chemical stability in solid electrolytes is a grand challenge for the synthesis of solid electrolytes. Herein we report the design of aliovalent substitution of Li4SnS4 to achieve high conduction and excellent air stability based on the hard and soft acids and bases theory. The composition of Li3.833Sn0.833As 0.166S4 has a high ionic conductivity of 1.39 mS/cm 1 at 25 C. Considering the high Li+ transference number, this phase conducts Li+ as well as carbonate-based liquid electrolytes. This research also addresses the compatibility of the sulfide-based solid electrolytes through chemical passivation.

  3. Solvate Structures and Computational/Spectroscopic Characterization of LiPF6 Electrolytes

    SciTech Connect

    Han, Sang D.; Yun, Sung-Hyun; Borodin, Oleg; Seo, D. M.; Sommer, Roger D.; Young, Victor G.; Henderson, Wesley A.

    2015-04-23

    Raman spectroscopy is a powerful method for identifying ion-ion interactions, but only if the vibrational band signature for the anion coordination modes can be accurately deciphered. The present study characterizes the PF6- anion P-F Raman symmetric stretching vibrational band for evaluating the PF6-...Li+ cation interactions within LiPF6 crystalline solvates to create a characterization tool for liquid electrolytes. To facilitate this, the crystal structures for two new solvates—(G3)1:LiPF6 and (DEC)2:LiPF6 with triglyme and diethyl carbonate, respectively—are reported. The information obtained from this analysis provides key guidance about the ionic association information which may be obtained from a Raman spectroscopic evaluation of electrolytes containing the LiPF6 salt and aprotic solvents. Of particular note is the overlap of the Raman bands for both solvent-separated ion pair (SSIP) and contact ion pair (CIP) coordination in which the PF6- anions are uncoordinated or coordinated to a single Li+ cation, respectively.

  4. Facile Synthesis of Boron-Doped rGO as Cathode Material for High Energy Li-O2 Batteries.

    PubMed

    Wu, Feng; Xing, Yi; Li, Li; Qian, Ji; Qu, Wenjie; Wen, Jianguo; Miller, Dean; Ye, Yusheng; Chen, Renjie; Amine, Khalil; Lu, Jun

    2016-09-14

    To improve the electrochemical performance of the high energy Li-O2 batteries, it is important to design and construct a suitable and effective oxygen-breathing cathode. Herein, a three-dimensional (3D) porous boron-doped reduction graphite oxide (B-rGO) material with a hierarchical structure has been prepared by a facile freeze-drying method. In this design, boric acid as the boron source helps to form the 3D porous structure, owing to its cross-linking and pore-forming function. This architecture facilitates the rapid oxygen diffusion and electrolyte penetration in the electrode. Meanwhile, the boron-oxygen functional groups linking to the carbon surface or edge serve as additional reaction sites to activate the ORR process. It is vital that boron atoms have been doped into the carbon lattices to greatly activate the electrons in the carbon π system, which is beneficial for fast charge under large current densities. Density functional theory calculation demonstrates that B-rGO exhibits much stronger interactions with Li5O6 clusters, so that B-rGO more effectively activates Li-O bonds to decompose Li2O2 during charge than rGO does. With B-rGO as a catalytic substrate, the Li-O2 battery achieves a high discharge capacity and excellent rate capability. Moreover, catalysts could be added into the B-rGO substrate to further lower the overpotential and enhance the cycling performance in future.

  5. Electrolyte stability determines scaling limits for solid-state 3D Li ion batteries.

    PubMed

    Ruzmetov, Dmitry; Oleshko, Vladimir P; Haney, Paul M; Lezec, Henri J; Karki, Khim; Baloch, Kamal H; Agrawal, Amit K; Davydov, Albert V; Krylyuk, Sergiy; Liu, Yang; Huang, Jiany; Tanase, Mihaela; Cumings, John; Talin, A Alec

    2012-01-11

    Rechargeable, all-solid-state Li ion batteries (LIBs) with high specific capacity and small footprint are highly desirable to power an emerging class of miniature, autonomous microsystems that operate without a hardwire for power or communications. A variety of three-dimensional (3D) LIB architectures that maximize areal energy density has been proposed to address this need. The success of all of these designs depends on an ultrathin, conformal electrolyte layer to electrically isolate the anode and cathode while allowing Li ions to pass through. However, we find that a substantial reduction in the electrolyte thickness, into the nanometer regime, can lead to rapid self-discharge of the battery even when the electrolyte layer is conformal and pinhole free. We demonstrate this by fabricating individual, solid-state nanowire core-multishell LIBs (NWLIBs) and cycling these inside a transmission electron microscope. For nanobatteries with the thinnest electrolyte, ≈110 nm, we observe rapid self-discharge, along with void formation at the electrode/electrolyte interface, indicating electrical and chemical breakdown. With electrolyte thickness increased to 180 nm, the self-discharge rate is reduced substantially, and the NWLIBs maintain a potential above 2 V for over 2 h. Analysis of the nanobatteries' electrical characteristics reveals space-charge limited electronic conduction, which effectively shorts the anode and cathode electrodes directly through the electrolyte. Our study illustrates that, at these nanoscale dimensions, the increased electric field can lead to large electronic current in the electrolyte, effectively shorting the battery. The scaling of this phenomenon provides useful guidelines for the future design of 3D LIBs.

  6. Practical performances of Li-ion polymer batteries with LiNi 0.8Co 0.2O 2, MCMB, and PAN-based gel electrolyte

    NASA Astrophysics Data System (ADS)

    Akashi, Hiroyuki; Shibuya, Mashio; Orui, Ken; Shibamoto, Gorou; Sekai, Koji

    The practical performances and thermal stability of Li-ion polymer batteries with LiNi 0.8Co 0.2O 2, mesocarbon microbead-based graphite, and poly(acrylonitrile) (PAN)-based gel electrolytes are reported. The gel electrolyte, which shows a fire-retardance by itself as well as good chemical stability effectively improved thermal stability of the Li-ion polymer battery up to 170 °C. We also found that the mesocarbon microbead-based graphite showed better coulombic efficiency even though the gel electrolyte contained PC and GBL. An evaluation of cell performances showed that the electrodes and the gel electrolyte were promising material for a next-generation Li-ion polymer battery.

  7. PC based electrolytes with LiDFOB as an alternative salt for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Knight, Brandon M.

    Lithium-ion batteries (LIBs) have been greatly sought after as a source of renewable energy storage. LIBs have a wide range of applications including but not limited portable electronic devices, electric vehicles, and power tools. As a direct result of their commercial viability an insatiable hunger for knowledge, advancement within the field of LIBs has been omnipresent for the last two decades. However, there are set backs evident within the LIB field; most notably the limitations of standard electrolyte formulations and LiPF6 lithium salt. The standard primary carbonate of ethylene carbonate (EC) has a very limited operating range due to its innate physical properties, and the LiPF6 salt is known to readily decompose to form HF which can further degrade LIB longevity. The goal of our research is to explore the use of a new primary salt LiDFOB in conjunction with a propylene carbonate based electrolyte to establish a more flexible electrolyte formulation by constructing coin cells and cycling them under various conditions to give a clear understanding of each formulation inherent performance capabilities. Our studies show that 1.2M LiDFOB in 3:7 PC/EMC + 1.5% VC is capable of performing comparably to the standard 1.2M LiPF6 in 3:7 EC/EMC at 25°C and the PC electrolyte also illustrates performance superior to the standard at 55°C. The degradation of lithium manganese spinel electrodes, including LiNi 0.5Mn1.5O4, is an area of great concern within the field of lithium ion batteries (LIBs). Manganese containing cathode materials frequently have problems associated with Mn dissolution which significantly reduces the cycle life of LIB. Thus the stability of the cathode material is paramount to the performance of Mn spinel cathode materials in LIBs. In an effort to gain a better understanding of the stability of LiNi0.5 Mn1.5O4 in common LiPF6/carbonate electrolytes, samples were stored at elevated temperature in the presence of electrolyte. Then after storage both

  8. Effect of organic acids and nano-sized ceramic doping on PEO-based solid polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Park, Jae Won; Jeong, Euh Duck; Won, Mi-Sook; Shim, Yoon-Bo

    Composite solid polymer electrolytes (CSPEs) consisting of polyethyleneoxide (PEO), LiClO 4, organic acids (malonic, maleic, and carboxylic acids), and/or Al 2O 3 were prepared in acetonitrile. CSPEs were characterized by Brewster Angle Microscopy (BAM), thermal analysis, ac impedance, cyclic voltammetry, and tested for charge-discharge capacity with the Li or LiNi 0.5Co 0.5O 2 electrodes coated on stainless steel (SS). The morphologies of the CSPE films were homogeneous and porous. The differential scanning calorimetric (DSC) results suggested that performance of the CSPE film was highly enhanced by the acid and inorganic additives. The composite membrane doped with organic acids and ceramic showed good conductivity and thermal stability. The ac impedance data, processed by non-linear least square (NLLS) fitting, showed good conducting properties of the composite films. The ionic conductivity of the film consisting of (PEO) 8LiClO 4:citric acid (99.95:0.05, w/w%) was 3.25 × 10 -4 S cm -1 and 1.81 × 10 -4 S cm -1 at 30 °C. The conductivity has further improved to 3.81 × 10 -4 S cm -1 at 20 °C by adding 20 w/w% Al 2O 3 filler to the (PEO) 8LiClO 4 + 0.05% carboxylic acid composite. The experimental data for the full cell showed an upper limit voltage window of 4.7 V versus Li/Li + for CSPE at room temperature.

  9. Importance of Reaction Kinetics and Oxygen Crossover in aprotic Li-O2 Batteries Based on a Dimethyl Sulfoxide Electrolyte.

    PubMed

    Marinaro, M; Balasubramanian, P; Gucciardi, E; Theil, S; Jörissen, L; Wohlfahrt-Mehrens, M

    2015-09-21

    Although still in their embryonic state, aprotic rechargeable Li-O2 batteries have, theoretically, the capabilities of reaching higher specific energy densities than Li-ion batteries. There are, however, significant drawbacks that must be addressed to allow stable electrochemical performance; these will ultimately be solved by a deeper understanding of the chemical and electrochemical processes occurring during battery operations. We report a study on the electrochemical and chemical stability of Li-O2 batteries comprising Au-coated carbon cathodes, a dimethyl sulfoxide (DMSO)-based electrolyte and Li metal negative electrodes. The use of the aforementioned Au-coated cathodes in combination with a 1 M lithium bis(trifluoromethane)sulfonimide (LiTFSI)-DMSO electrolyte guarantees very good cycling stability (>300 cycles) by minimizing eventual side reactions. The main drawbacks arise from the high reactivity of the Li metal electrode when in contact with the O2 -saturated DMSO-based electrolyte.

  10. Use of phosphoranimines to reduce organic carbonate content in Li-ion battery electrolytes

    DOE PAGES

    Dufek, Eric J.; Klaehn, John R.; McNally, Joshua S.; ...

    2016-05-09

    In this study, the use of phosphoranimines (PAs), a class of linear, monomeric phosphazenes, as electrolytes for Li-ion battery applications has been investigated as a route to improve safety and stability for Li-ion batteries. Of the potential PAs for use in battery applications, this work focuses on the initial synthetic preparation and analysis of N-trimethylsilyl-P,P-bis((2-methoxyethoxy)ethoxy)-P-ethylphosphoranimine (PA-5). PA-5 has high LiPF6 solubility in excess of 2 M, high thermal stability with a melting point below -80°C and high thermal stability as a neat compound to at least 250°C. As part of electrolyte blends, the inclusion of PA-5 shifts the onset ofmore » thermal degradation by close to 40°C at 35% loading and by 20°C at a 10% loading, improves the low temperature performance of the electrolyte, and when used as a primary solvent leads to increases in the flash point (by 20°C) when compared to more traditional EC:EMC blends. Cycling capabilities of full-coin cells with graphite negative electrodes and Li1+w[Ni0.5Mn0.3Co0.2]1-wO2 positive electrodes using PA-5:EC:EMC electrolyte blends are comparable with the performance seen for traditional EC:EMC blends. Analysis of the impact of the use of additives such as vinylene carbonate in PA-5:EC:EMC blended electrolyte results in enhanced capacity retention and improved coulombic efficiency.« less

  11. Use of phosphoranimines to reduce organic carbonate content in Li-ion battery electrolytes

    SciTech Connect

    Dufek, Eric J.; Klaehn, John R.; McNally, Joshua S.; Rollins, Harry W.; Jamison, David K.

    2016-05-09

    In this study, the use of phosphoranimines (PAs), a class of linear, monomeric phosphazenes, as electrolytes for Li-ion battery applications has been investigated as a route to improve safety and stability for Li-ion batteries. Of the potential PAs for use in battery applications, this work focuses on the initial synthetic preparation and analysis of N-trimethylsilyl-P,P-bis((2-methoxyethoxy)ethoxy)-P-ethylphosphoranimine (PA-5). PA-5 has high LiPF6 solubility in excess of 2 M, high thermal stability with a melting point below -80°C and high thermal stability as a neat compound to at least 250°C. As part of electrolyte blends, the inclusion of PA-5 shifts the onset of thermal degradation by close to 40°C at 35% loading and by 20°C at a 10% loading, improves the low temperature performance of the electrolyte, and when used as a primary solvent leads to increases in the flash point (by 20°C) when compared to more traditional EC:EMC blends. Cycling capabilities of full-coin cells with graphite negative electrodes and Li1+w[Ni0.5Mn0.3Co0.2]1-wO2 positive electrodes using PA-5:EC:EMC electrolyte blends are comparable with the performance seen for traditional EC:EMC blends. Analysis of the impact of the use of additives such as vinylene carbonate in PA-5:EC:EMC blended electrolyte results in enhanced capacity retention and improved coulombic efficiency.

  12. Electrolytes for Low-Temperature Operation of Li-CFx Cells

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Whitacre, Jay F.; Bugga, Ratnakumar V.; Prakash, G. K. Surya; Bhalla, Pooja; Smith, Kiah

    2009-01-01

    A report describes a study of electrolyte compositions selected as candidates for improving the low-temperature performances of primary electrochemical cells that contain lithium anodes and fluorinated carbonaceous (CFx) cathodes. This study complements the developments reported in Additive for Low-Temperature Operation of Li-(CF)n Cells (NPO- 43579) and Li/CFx Cells Optimized for Low-Temperature Operation (NPO- 43585), which appear elsewhere in this issue of NASA Tech Briefs. Similar to lithium-based electrolytes described in several previous NASA Tech Briefs articles, each of these electrolytes consisted of a lithium salt dissolved in a nonaqueous solvent mixture. Each such mixture consisted of two or more of the following ingredients: propylene carbonate (PC); 1,2-dimethoxyethane (DME); trifluoropropylene carbonate; bis(2,2,2-trifluoroethyl) ether; diethyl carbonate; dimethyl carbonate; and ethyl methyl carbonate. The report describes the physical and chemical principles underlying the selection of the compositions (which were not optimized) and presents results of preliminary tests made to determine effects of the compositions upon the low-temperature capabilities of Li-CFx cells, relative to a baseline composition of LiBF4 at a concentration of 1.0 M in a solvent comprising equal volume parts of PC and DME.

  13. Improved Low-Temperature Performance of Li-Ion Cells Using New Electrolytes

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Buga, Ratnakumar V.; Gozdz, Antoni S.; Mani, Suresh

    2010-01-01

    As part of the continuing efforts to develop advanced electrolytes to improve the performance of lithium-ion cells, especially at low temperatures, a number of electrolyte formulations have been developed that result in improved low-temperature performance (down to 60 C) of 26650 A123Systems commercial lithium-ion cells. The cell type/design, in which the new technology has been demonstrated, has found wide application in the commercial sector (i.e., these cells are currently being used in commercial portable power tools). In addition, the technology is actively being considered for hybrid electric vehicle (HEV) and electric vehicle (EV) applications. In current work, a number of low-temperature electrolytes have been developed based on advances involving lithium hexafluorophosphate-based solutions in carbonate and carbonate + ester solvent blends, which have been further optimized in the context of the technology and targeted applications. The approaches employed, which include the use of ternary mixtures of carbonates, the use of ester co-solvents [e.g., methyl butyrate (MB)], and optimized lithium salt concentrations (e.g., LiPF6), were compared with the commercial baseline electrolyte, as well as an electrolyte being actively considered for DoE HEV applications and previously developed by a commercial enterprise, namely LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC)(30:70%).

  14. Li doped ZnO thin films for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Sandeep, K. M.; Bhat, Shreesha; Serrao, F. J.; Dharmaprakash, S. M.

    2016-05-01

    We have prepared undoped (ZnO) and Li doped ZnO (LZO) thin films using cost effective sol gel spin coating method.The structural properties were analyzed by X-ray diffraction, and it showed that Li ions occupied interstitial positions in the LZO film. The optical properties like band bending effect, absorption length, band edge sharpness, which have direct impact on solar cell performance has been calculated. The room temperature photoluminescence spectra of the films showed dominant blue emission with CIE coordinate numbers (0.1384, 0.0836) for ZnO and (0.1356, 0.0910) for LZO. The dominating wavelength of the blue emission is present at 470.9 nm and 472.3 nm for ZnO and LZO films respectively. The structural and optical parameters determined in the present study could be used in LED applications.

  15. Electrolytes with Improved Safety Characteristics for High Voltage, High Specific Energy Li-ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Krause, F. C.; Hwang, C.; West, W. C.; Soler, J.; Whitcanack, L. W.; Prakash, G. K. S.; Ratnakumar, B. V.

    2012-01-01

    (1) NASA is actively pursuing the development of advanced electrochemical energy storage and conversion devices for future lunar and Mars missions; (2) The Exploration Technology Development Program, Energy Storage Project is sponsoring the development of advanced Li-ion batteries and PEM fuel cell and regenerative fuel cell systems for the Altair Lunar Lander, Extravehicular Activities (EVA), and rovers and as the primary energy storage system for Lunar Surface Systems; (3) At JPL, in collaboration with NASA-GRC, NASA-JSC and industry, we are actively developing advanced Li-ion batteries with improved specific energy, energy density and safety. One effort is focused upon developing Li-ion battery electrolyte with enhanced safety characteristics (i.e., low flammability); and (4) A number of commercial applications also require Li-ion batteries with enhanced safety, especially for automotive applications.

  16. The effectiveness of electrolyte additives in fluorinated electrolytes for high voltage Li[Ni0.4Mn0.4Co0.2]O2/graphite pouch Li-ion cells

    NASA Astrophysics Data System (ADS)

    Xia, Jian; Petibon, R.; Xiao, A.; Lamanna, W. M.; Dahn, J. R.

    2016-10-01

    The effectiveness of electrolyte additives in fluorinated electrolytes containing 1 M LiPF6/fluoroethylene carbonate:bis (2,2,2-trifluoroethyl) carbonate (1:1 w:w) were studied in high voltage Li(Ni0.4Mn0.4Co0.2)O2/graphite pouch cells tested to 4.5 V. The results showed that fluorinated electrolytes containing prop-1-ene-1,3-sultone alone or in combination with other additives exhibited significant improvements in terms of coulombic efficiency and charge endpoint capacity slippage during UHPC cycling, voltage drop during storage, as well as capacity retention during long-term cycling compared with state-of-the-art ethylene carbonate-based (ethylene carbonate: ethylmethyl carbonate 3:7) or sulfolane-based electrolytes (sulfolane: ethylmethyl carbonate 3:7) with some promising additive blends. These results indicate that fluorinated electrolytes offer an interesting alternative for high voltage Li-ion batteries.

  17. Nitrogen-doped graphene-decorated LiVPO4F nanocomposite as high-voltage cathode material for rechargeable lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Cui, Kai; Hu, Shuchun; Li, Yongkui

    2016-09-01

    In this study, nitrogen-doped graphene decorated LiVPO4F cathode material is firstly synthesized via a facile method. Well-dispersed LiVPO4F nanoparticles are embedded in nitrogen-doped graphene nanosheets, forming an effective conducting network. The added nitrogen-doped graphene nanosheets greatly enhance the electronic conductivity and Li-ion diffusion of LiVPO4F sample. When tested as cathode material for rechargeable lithium-ion batteries, the hybrid electrode exhibits superior high-rate performance and long-term cycling stability between 3.0 and 4.5 V. It delivers a large discharge capacity of 152.7 mAhg-1 at 0.1 C and shows a capacity retention of 97.8% after 60 cycles. Moreover, a reversible capacity of 90.1 mAhg-1 is maintained even after 500 cycles at a high rate of 20 C. The charge-transfer resistance of LiVPO4F electrode is also reduced in the nitrogen-doped graphene, revealing that its electrode-electrolyte complex reactions take place easily and thus improve the electrochemical performance. The above results provide a facile and effective strategy for the synthesis of LiVPO4F cathode material for high-performance lithium-ion batteries.

  18. EMF measurements on the Li-Al/Ni/sub 3/S/sub 2/ couple in molten salt electrolytes

    SciTech Connect

    Tomczuk, Z.; Redey, L.; Vissers, D.R.

    1983-05-01

    The (emf) vs. temperature curve for the Li-Al/Ni/sub 3/S/sub 2/ couple was determined in 58.2 mol percen (m/o) LiCl-41.8 m/o KCl (eutectic electrolyte), 49.1 m/o LiCl-50.9 m/o KCl (KCl-rich electrolyte), 69.6 m/o LiCl-30.4 m/o KCl (LiCl-rich electrolyte), and in 22 m/o Lif-31 m/o LiCl-47 m/o LiBr electrolyte. The results indicate that with these electrolytes the emf value of the couple at a given temperature is independent of the electrolyte composition. Equilibrium emf values were obtained instantaneously upon heating or cooling at rates of about0.2/sup 0/C/min, while at higher rates ( about0.5/sup 0/C/ min) equilibrium values were obtained after about 1 1/2 hr at a given temperature. X-ray diffraction analyses of the positive electrodes from the cells tested indicate that the only nickel-sulfur phase formed in the electrode reaction is Ni/sub 3/S/sub 2/. Thermochemical analyses also suggest Ni/sub 3/S/sub 2/ as the active nickel sulfide phase.

  19. Reshaping Lithium Plating/Stripping Behavior via Bifunctional Polymer Electrolyte for Room-Temperature Solid Li Metal Batteries.

    PubMed

    Zeng, Xian-Xiang; Yin, Ya-Xia; Li, Nian-Wu; Du, Wen-Cheng; Guo, Yu-Guo; Wan, Li-Jun

    2016-12-14

    High-energy rechargeable Li metal batteries are hindered by dendrite growth due to the use of a liquid electrolyte. Solid polymer electrolytes, as promising candidates to solve the above issue, are expected to own high Li ion conductivity without sacrificing mechanical strength, which is still a big challenge to realize. In this study, a bifunctional solid polymer electrolyte exactly having these two merits is proposed with an interpenetrating network of poly(ether-acrylate) (ipn-PEA) and realized via photopolymerization of ion-conductive poly(ethylene oxide) and branched acrylate. The ipn-PEA electrolyte with facile processing capability integrates high mechanical strength (ca. 12 GPa) with high room-temperature ionic conductance (0.22 mS cm(-1)), and significantly promotes uniform Li plating/stripping. Li metal full cells assembled with ipn-PEA electrolyte and cathodes within 4.5 V vs Li(+)/Li operate effectively at a rate of 5 C and cycle stably at a rate of 1 C at room temperature. Because of its fabrication simplicity and compelling characteristics, the bifunctional ipn-PEA electrolyte reshapes the feasibility of room-temperature solid-state Li metal batteries.

  20. A Unique Hybrid Quasi-Solid-State Electrolyte for Li-O2 Batteries with Improved Cycle Life and Safety.

    PubMed

    Yi, Jin; Zhou, Haoshen

    2016-09-08

    In the context of the development of electric vehicle to solve the contemporary energy and environmental issues, the possibility of pushing future application of Li-O2 batteries as a power source for electric vehicles is particularly attractive. However, safety concerns, mainly derived from the use of flammable organic liquid electrolytes, become a major bottleneck for the strategically crucial applications of Li-O2 batteries. To overcome this issue, rechargeable solid-state Li-O2 batteries with enhanced safety is regarded as an appealing candidate. In this study, a hybrid quasi-solid-state electrolyte combing a polymer electrolyte with a ceramic electrolyte is first designed and explored for Li-O2 batteries. The proposed rechargeable solid-state Li-O2 battery delivers improved cycle life (>100 cycles) and safety. The feasibility study demonstrates that the hybrid quasi-solid-state electrolytes could be employed as a promising alternative strategy for the development of rechargeable Li-O2 batteries, hence encouraging more efforts devoted to explore other hybrid solid-state electrolytes for Li-O2 batteries upon future application.

  1. Structural and Dielectric Properties of Ionic Liquid Doped Metal Organic Framework based Polymer Electrolyte Nanocomposites

    NASA Astrophysics Data System (ADS)

    Dutta, Rituraj; Kumar, Ashok

    2016-10-01

    Metal Organic Frameworks (MOFs) are mesoporous materials that can be treated as potential hosts for trapping guest molecules in their pores. Ion conduction and phase behavior dynamics of Ionic Liquids (ILs) can be controlled by tunable interactions of MOFs with the ILs. MOFs incorporated with ionic liquid can be dispersed in the polymers to synthesize polymer electrolyte nanocomposites with high ionic conductivity, electrochemical and thermal stability for applications in energy storage and conversion devices such as rechargeable Li-ion batteries. In the present work we have synthesized Cu-based MOF [Cu3(l,3,5-benzene tricarboxylate)2(H2O)] incorporated with the ionic liquid 1-Butyl-3-methylimidazolium bromide at different weight ratios of MOF and IL. The synthesized MOF-IL composites are dispersed in Poly (ethylene oxide) (PEO). Frequency dependent behavior of permittivity and dielectric loss of the nanocomposites depict the non-Debye dielectric relaxation mechanism. The room temperature Nyquist plots reveal decreasing bulk resistance upto 189 Ω with optimum ionic conductivity of 1.3×10-3S cm-1at maximum doping concentration of IL in the nanocomposite system.

  2. Li-Ion Conductivity and Phase Stability of Ca-Doped LiBH4 under High Pressure.

    PubMed

    Mezaki, Takeya; Kuronuma, Yota; Oikawa, Itaru; Kamegawa, Atsunori; Takamura, Hitoshi

    2016-10-17

    The effect of Ca doping on the Li-ion conductivity and phase stability of the rock-salt-type LiBH4 phase emerging under high pressures in the range of gigapascals has been investigated. In situ electrochemical measurements under high pressure were performed using a cubic-anvil-type apparatus. Ca doping drastically enhanced the ionic conductivity of the rock-salt-type phase: the ionic conductivity of undoped and 5 mol %Ca-doped LiBH4 was 2.2 × 10(-4) and 1.4 × 10(-2) S·cm(-1) under 4.0 GPa at 220 °C, respectively. The activation volume of LiBH4-5 mol %Ca(BH4)2, at 3.2 cm(3)·mol(-1), was comparable to that of other fast ionic conductors, such as lithium titanate and NASICONs. Moreover, Ca-doped LiBH4 showed lithium plating-stripping behavior in a cyclic voltammogram. These results indicate that the conductivity enhancement by Ca doping can be attributed to the formation of a LiBH4-Ca(BH4)2 solid solution; however, the solid solution decomposed into the orthorhombic LiBH4 phase and the orthorhombic Ca(BH4)2 phase after unloading the high pressure.

  3. Effect of impurities and moisture on lithium bisoxalatoborate (LiBOB) electrolyte performance in lithium-ion cells

    NASA Astrophysics Data System (ADS)

    Yang, L.; Furczon, M. M.; Xiao, A.; Lucht, B. L.; Zhang, Z.; Abraham, D. P.

    Electrolytes containing LiB(C 2O 4) 2 (LiBOB) salts are of increasing interest for lithium-ion cells for several reasons that include their ability to form a stable solid electrolyte interphase on graphite electrodes. However, cells containing these electrolytes often show inconsistent performance because of impurities in the LiBOB salt. In this work we compare cycling and impedance data from cells containing electrolytes with LiBOB that was obtained commercially and LiBOB purified by a rigorous recrystallization procedure. We relate the difference in performance to a lithium oxalate impurity that may be a residual from the salt manufacturing process. We also examine the reaction of LiBOB with water to determine the effect of salt storage in high-humidity environments. Although LiBOB electrolytes containing trace amounts (∼100 ppm) of moisture appear relatively stable, higher moisture contents (∼1 wt%) lead to observable salt decomposition resulting in the generation of B(C 2O 4)(OH) and LiB(C 2O 4)(OH) 2 compounds that do not dissolve in typical carbonate solutions and impair lithium-ion cell performance.

  4. On the Oxidation State of Manganese Ions in Li-Ion Battery Electrolyte Solutions.

    PubMed

    Banerjee, Anjan; Shilina, Yuliya; Ziv, Baruch; Ziegelbauer, Joseph M; Luski, Shalom; Aurbach, Doron; Halalay, Ion C

    2017-02-08

    We demonstrate herein that Mn(3+) and not Mn(2+), as commonly accepted, is the dominant dissolved manganese cation in LiPF6-based electrolyte solutions of Li-ion batteries with lithium manganate spinel positive and graphite negative electrodes chemistry. The Mn(3+) fractions in solution, derived from a combined analysis of electron paramagnetic resonance and inductively coupled plasma spectroscopy data, are ∼80% for either fully discharged (3.0 V hold) or fully charged (4.2 V hold) cells, and ∼60% for galvanostatically cycled cells. These findings agree with the average oxidation state of dissolved Mn ions determined from X-ray absorption near-edge spectroscopy data, as verified through a speciation diagram analysis. We also show that the fractions of Mn(3+) in the aprotic nonaqueous electrolyte solution are constant over the duration of our experiments and that disproportionation of Mn(3+) occurs at a very slow rate.

  5. A synthesis of crystalline Li7P3S11 solid electrolyte from 1,2-dimethoxyethane solvent

    NASA Astrophysics Data System (ADS)

    Ito, Seitaro; Nakakita, Moeka; Aihara, Yuichi; Uehara, Takahiro; Machida, Nobuya

    2014-12-01

    A crystalline solid electrolyte, Li7P3S11, was synthesized by a liquid-phase reaction of Li2S and P2S5 in an organic solvent. A precursor, which was a mixture of solvated Li3PS4 and Li4P2S7, was prepared by mixing Li2S and P2S5 powders in 1,2-dimethoxyethane (DME) solvent. After a vacuum drying of the precursor, the crystalline phase of Li7P3S11 was obtained by heat treatment at 250 °C for 1 h in Ar atmosphere. The Li7P3S11 sample showed high ionic conductivity of 2.7 × 10-4 S cm-1 at room temperature. The liquid-phase synthesis of the solid electrolyte has advantages for mass-production of all-solid-state batteries.

  6. Structure and properties of Li-ion conducting polymer gel electrolytes based on ionic liquids of the pyrrolidinium cation and the bis(trifluoromethanesulfonyl)imide anion

    NASA Astrophysics Data System (ADS)

    Pitawala, Jagath; Navarra, Maria Assunta; Scrosati, Bruno; Jacobsson, Per; Matic, Aleksandar

    2014-01-01

    We have investigated the structure and physical properties of Li-ion conducting polymer gel electrolytes functionalized with ionic liquid/lithium salt mixtures. The membranes are based on poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, PVdF-HFP, and two ionic liquids: pyrrolidinium cations, N-butyl-N-methylpyrrolidinium (PyR14+), N-butyl-N-ethylpyrrolidinium (PyR24+), and bis(trifluoromethanesulfonyl)imide anion (TFSI). The ionic liquids where doped with 0.2 mol kg-1 LiTFSI. The resulting membranes are freestanding, flexible, and nonvolatile. The structure of the polymer and the interactions between the polymer and the ionic liquid electrolyte have been studied using Raman spectroscopy. The ionic conductivity of the membranes has been studied using dielectric spectroscopy whereas the thermal properties were investigated using differential scanning caloriometry (DSC). These results show that there is a weak, but noticeable, influence on the physical properties of the ionic liquid by the confinement in the membrane. We observe a change in the Li-ion coordination, conformation of the anion, the fragility and a slight increase of the glass transition temperatures for IL/LiTFSI mixtures in the membranes compared to the neat mixtures. The effect can be related to the confinement of the liquid in the membrane and/or to interactions with the PVdF-HFP polymer matrix where the crystallinity is decreased compared to the starting polymer powder.

  7. Non-aqueous solution preparation of doped and undoped Li{sub x}Mn{sub y}O{sub z}

    DOEpatents

    Boyle, T.J.; Voigt, J.A.

    1997-05-20

    A method is described for generation of phase-pure doped and undoped Li{sub x}Mn{sub y}O{sub z} precursors. The method of this invention uses organic solutions instead of aqueous solutions or nonsolution ball milling of dry powders to produce phase-pure precursors. These precursors can be used as cathodes for lithium-polymer electrolyte batteries. Dopants may be homogeneously incorporated to alter the characteristics of the powder. 1 fig.

  8. Pseudo-binary electrolyte, LiBH4-LiCl, for bulk-type all-solid-state lithium-sulfur battery

    NASA Astrophysics Data System (ADS)

    Unemoto, Atsushi; Chen, ChunLin; Wang, Zhongchang; Matsuo, Motoaki; Ikeshoji, Tamio; Orimo, Shin-ichi

    2015-06-01

    The ionic conduction and electrochemical and thermal stabilities of the LiBH4-LiCl solid-state electrolyte were investigated for use in bulk-type all-solid-state lithium-sulfur batteries. The LiBH4-LiCl solid-state electrolyte exhibiting a lithium ionic conductivity of log ≤ft( σ /S c{{m}-1} \\right)=-3.3 at 373 K, forms a reversible interface with a lithium metal electrode and has a wide electrochemical potential window up to 5 V. By means of the high-energy mechanical ball-milling technique, we prepared a composite powder consisting of elemental sulfur and mixed conductive additive, i.e., Ketjen black and Maxsorb. In that composite powder, homogeneous dispersion of the materials is achieved on a nanometer scale, and thereby a high concentration of the interface among them is induced. Such nanometer-scale dispersals of both elemental sulfur and carbon materials play an important role in enhancing the electrochemical reaction of elemental sulfur. The highly deformable LiBH4-LiCl electrolyte assists in the formation of a high concentration of tight interfaces with the sulfur-carbon composite powder. The LiBH4-LiCl electrolyte also allows the formation of the interface between the positive electrode and the electrolyte layers, and thus the Li-ion transport paths are established at that interface. As a result, our battery exhibits high discharge capacities of 1377, 856, and 636 mAh g-1 for the 1st, 2nd, and 5th discharges, respectively, at 373 K. These results imply that complex hydride-based solid-state electrolytes that contain Cl-ions in the crystal would be integrated into rechargeable batteries.

  9. Pseudo-binary electrolyte, LiBH4-LiCl, for bulk-type all-solid-state lithium-sulfur battery.

    PubMed

    Unemoto, Atsushi; Chen, ChunLin; Wang, Zhongchang; Matsuo, Motoaki; Ikeshoji, Tamio; Orimo, Shin-Ichi

    2015-01-26

    The ionic conduction and electrochemical and thermal stabilities of the LiBH4-LiCl solid-state electrolyte were investigated for use in bulk-type all-solid-state lithium-sulfur batteries. The LiBH4-LiCl solid-state electrolyte exhibiting a lithium ionic conductivity of [Formula: see text] at 373 K, forms a reversible interface with a lithium metal electrode and has a wide electrochemical potential window up to 5 V. By means of the high-energy mechanical ball-milling technique, we prepared a composite powder consisting of elemental sulfur and mixed conductive additive, i.e., Ketjen black and Maxsorb. In that composite powder, homogeneous dispersion of the materials is achieved on a nanometer scale, and thereby a high concentration of the interface among them is induced. Such nanometer-scale dispersals of both elemental sulfur and carbon materials play an important role in enhancing the electrochemical reaction of elemental sulfur. The highly deformable LiBH4-LiCl electrolyte assists in the formation of a high concentration of tight interfaces with the sulfur-carbon composite powder. The LiBH4-LiCl electrolyte also allows the formation of the interface between the positive electrode and the electrolyte layers, and thus the Li-ion transport paths are established at that interface. As a result, our battery exhibits high discharge capacities of 1377, 856, and 636 mAh g(-1) for the 1st, 2nd, and 5th discharges, respectively, at 373 K. These results imply that complex hydride-based solid-state electrolytes that contain Cl-ions in the crystal would be integrated into rechargeable batteries.

  10. Characterization of proton conducting blend polymer electrolyte using PVA-PAN doped with NH4SCN

    NASA Astrophysics Data System (ADS)

    Premalatha, M.; Mathavan, T.; Selvasekarapandian, S.; Genova, F. Kingslin Mary; Umamaheswari, R.

    2016-05-01

    Polymer electrolytes with proton conductivity based on blend polymer using polyvinyl alcohol (PVA) and poly acrylo nitrile (PAN) doped with ammonium thiocyanate have been prepared by solution casting method using DMF as solvent. The complex formation between the blend polymer and the salt has been confirmed by FTIR Spectroscopy. The amorphous nature of the blend polymer electrolytes have been confirmed by XRD analysis. The highest conductivity at 303 K has been found to be 3.25 × 10-3 S cm-1 for 20 mol % NH4SCN doped 92.5PVA:7.5PAN system. The increase in conductivity of the doped blend polymer electrolytes with increasing temperature suggests the Arrhenius type thermally activated process. The activation energy is found to be low (0.066 eV) for the highest conductivity sample.

  11. Chemical stability of Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide, an electrolyte salt for Li-ion cells

    DOE PAGES

    Shkrob, Ilya A.; Pupek, Krzysztof Z.; Gilbert, James A.; ...

    2016-12-01

    Lithium hexafluorophosphate (LiPF6) is ubiquitous in commercial lithium-ion batteries, but it is hydrolytically unstable and corrosive on electrode surfaces. Using a more stable salt would confer multiple benefits for high-voltage operation, but many such electrolyte systems facilitate anodic dissolution and pitting corrosion of aluminum current collectors that negate their advantages. Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide (LiTDI) is a new salt that was designed specifically for high-voltage cells. In this study we demonstrate that in carbonate electrolytes, LiTDI prevents anodic dissolution of Al current collectors, which places it into a select group of corrosion inhibitors. However, we also demonstrate that LiTDI becomes reduced onmore » lithiated graphite, undergoing sequential defluorination and yielding a thick and resistive solid-electrolyte interphase (SEI), which increases impedance and lowers electrode capacity. The mechanistic causes for this behavior are examined using computational chemistry methods in the light of recent spectroscopic studies. Here, we demonstrate that LiTDI reduction can be prevented by certain electrolyte additives, which include fluoroethylene carbonate, vinylene carbonate and lithium bis(oxalato)borate. This beneficial action is due to preferential reduction of these additives over LiTDI at a higher potential vs. Li/Li+, so the resulting SEI can prevent the direct reduction of LiTDI at lower potentials on the graphite electrode.« less

  12. Chemical stability of Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide, an electrolyte salt for Li-ion cells

    SciTech Connect

    Shkrob, Ilya A.; Pupek, Krzysztof Z.; Gilbert, James A.; Trask, Stephen E.; Abraham, Daniel P.

    2016-12-01

    Lithium hexafluorophosphate (LiPF6) is ubiquitous in commercial lithium-ion batteries, but it is hydrolytically unstable and corrosive on electrode surfaces. Using a more stable salt would confer multiple benefits for high-voltage operation, but many such electrolyte systems facilitate anodic dissolution and pitting corrosion of aluminum current collectors that negate their advantages. Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide (LiTDI) is a new salt that was designed specifically for high-voltage cells. In this study we demonstrate that in carbonate electrolytes, LiTDI prevents anodic dissolution of Al current collectors, which places it into a select group of corrosion inhibitors. However, we also demonstrate that LiTDI becomes reduced on lithiated graphite, undergoing sequential defluorination and yielding a thick and resistive solid-electrolyte interphase (SEI), which increases impedance and lowers electrode capacity. The mechanistic causes for this behavior are examined using computational chemistry methods in the light of recent spectroscopic studies. Here, we demonstrate that LiTDI reduction can be prevented by certain electrolyte additives, which include fluoroethylene carbonate, vinylene carbonate and lithium bis(oxalato)borate. This beneficial action is due to preferential reduction of these additives over LiTDI at a higher potential vs. Li/Li+, so the resulting SEI can prevent the direct reduction of LiTDI at lower potentials on the graphite electrode.

  13. Novel Solid Electrolytes for Li-Ion Batteries: A Perspective from Electron Microscopy Studies

    SciTech Connect

    Ma, Cheng; Chi, Miaofang

    2016-06-08

    Solid electrolytes can simultaneously overcome two of the most formidable challenges of Li-ion batteries: the severe safety issues and insufficient energy densities. However, before they can be implemented in actual batteries, the ionic conductivity needs to be improved and the interface with electrodes must be optimized. The prerequisite for addressing these issues is a thorough understanding of the material’s behavior at the microscopic and/or the atomic level. (Scanning) transmission electron microscopy is a powerful tool for this purpose, as it can reach an ultrahigh spatial resolution. Here, we review recent electron microscopy investigations on the ion transport behavior in solid electrolytes and their interfaces. Specifically, three aspects will be highlighted: the influence of grain interior atomic configuration on ionic conductivity, the contribution of grain boundaries, and the behavior of solid electrolyte/electrode interfaces. In conclusion, based on this, the perspectives for future research will be discussed.

  14. Novel Solid Electrolytes for Li-Ion Batteries: A Perspective from Electron Microscopy Studies

    DOE PAGES

    Ma, Cheng; Chi, Miaofang

    2016-06-08

    Solid electrolytes can simultaneously overcome two of the most formidable challenges of Li-ion batteries: the severe safety issues and insufficient energy densities. However, before they can be implemented in actual batteries, the ionic conductivity needs to be improved and the interface with electrodes must be optimized. The prerequisite for addressing these issues is a thorough understanding of the material’s behavior at the microscopic and/or the atomic level. (Scanning) transmission electron microscopy is a powerful tool for this purpose, as it can reach an ultrahigh spatial resolution. Here, we review recent electron microscopy investigations on the ion transport behavior in solidmore » electrolytes and their interfaces. Specifically, three aspects will be highlighted: the influence of grain interior atomic configuration on ionic conductivity, the contribution of grain boundaries, and the behavior of solid electrolyte/electrode interfaces. In conclusion, based on this, the perspectives for future research will be discussed.« less

  15. Optimized Li-Ion Electrolytes Containing Triphenyl Phosphate as a Flame-Retardant Additive

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Bugga, Ratnakumar V.; Prakash, G. K. Surya; Krause, Frederick C.

    2011-01-01

    A number of future NASA missions involving the exploration of the Moon and Mars will be human-rated and thus require high-specific-energy rechargeable batteries that possess enhanced safety characteristics. Given that Li-ion technology is the most viable rechargeable energy storage device for near-term applications, effort has been devoted to improving the safety characteristics of this system. There is also a strong desire to develop Li-ion batteries with improved safety characteristics for terrestrial applications, most notably for hybrid electric vehicle (HEV) and plug-in hybrid electric vehicle (PHEV) automotive applications. Therefore, extensive effort has been devoted recently to developing non-flammable electrolytes to reduce the flammability of the cells/battery. A number of electrolyte formulations have been developed, including systems that (1) incorporate greater concentrations of the flame-retardant additive (FRA); (2) use di-2,2,2-trifluoroethyl carbonate (DTFEC) as a co-solvent; (3) use 2,2,2- trifluoroethyl methyl carbonate (TFEMC); (4) use mono-fluoroethylene carbonate (FEC) as a co-solvent and/or a replacement for ethylene carbonate in the electrolyte mixture; and (5) utilize vinylene carbonate as a "SEI promoting" electrolyte additive, to build on the favorable results previously obtained. To extend the family of electrolytes developed under previous work, a number of additional electrolyte formulations containing FRAs, most notably triphenyl phosphate (TPP), were investigated and demonstrated in experimental MCMB (mesocarbon micro beads) carbon- LiNi(0.8)Co(0.2)O2 cells. The use of higher concentrations of the FRA is known to reduce the flammability of the electrolyte solution, thus, a concentration range was investigated (i.e., 5 to 20 percent by volume). The desired concentration of the FRA is the highest amount tolerable without adversely affecting the performance in terms of reversibility, ability to operate over a wide temperature range, and

  16. Studies on the thermal breakdown of common Li-ion battery electrolyte components

    SciTech Connect

    Lamb, Joshua; Orendorff, Christopher J.; Roth, Emanuel Peter; Langendorf, Jill Louise

    2015-08-06

    While much attention is paid to the impact of the active materials on the catastrophic failure of lithium ion batteries, much of the severity of a battery failure is also governed by the electrolytes used, which are typically flammable themselves and can decompose during battery failure. The use of LiPF6 salt can be problematic as well, not only catalyzing electrolyte decomposition, but also providing a mechanism for HF production. This work evaluates the safety performance of the common components ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in the context of the gasses produced during thermal decomposition, looking at both the quantity and composition of the vapor produced. EC and DEC were found to be the largest contributors to gas production, both producing upwards of 1.5 moles of gas/mole of electrolyte. DMC was found to be relatively stable, producing very little gas regardless of the presence of LiPF6. EMC was stable on its own, but the addition of LiPF6 catalyzed decomposition of the solvent. As a result, while gas analysis did not show evidence of significant quantities of any acutely toxic materials, the gasses themselves all contained enough flammable components to potentially ignite in air.

  17. Studies on the thermal breakdown of common Li-ion battery electrolyte components

    DOE PAGES

    Lamb, Joshua; Orendorff, Christopher J.; Roth, Emanuel Peter; ...

    2015-08-06

    While much attention is paid to the impact of the active materials on the catastrophic failure of lithium ion batteries, much of the severity of a battery failure is also governed by the electrolytes used, which are typically flammable themselves and can decompose during battery failure. The use of LiPF6 salt can be problematic as well, not only catalyzing electrolyte decomposition, but also providing a mechanism for HF production. This work evaluates the safety performance of the common components ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in the context of the gasses producedmore » during thermal decomposition, looking at both the quantity and composition of the vapor produced. EC and DEC were found to be the largest contributors to gas production, both producing upwards of 1.5 moles of gas/mole of electrolyte. DMC was found to be relatively stable, producing very little gas regardless of the presence of LiPF6. EMC was stable on its own, but the addition of LiPF6 catalyzed decomposition of the solvent. As a result, while gas analysis did not show evidence of significant quantities of any acutely toxic materials, the gasses themselves all contained enough flammable components to potentially ignite in air.« less

  18. Study of novel nonflammable electrolytes in Sandia-built Li-ion cells.

    SciTech Connect

    Nagasubramanian, Ganesan; Orendorff, Christopher J.

    2010-04-01

    Even after decades of research, Li-ion cells still lack thermal stability. A number of approaches, including adding fire retardants or fluoro compounds to the electrolyte to mitigate fire, have been investigated. These additives improved the thermal stability of the cells (only marginally) but not enough for use in transportation applications. Recent investigations indicate that hydrofluoro-ethers are promising as nonflammable additives1. We describe here the results of our studies on electrolytes containing the hydrofluoro-ethers in cells fabricated at Sandia. In particular, we are investigating two solvents as nonflammable additives. These are: (1) 2-trifluoromethyl-3-methoxyperfluoropentane {l_brace}TMMP{r_brace} and (2) 2-trifluoro-2-fluoro-3-difluoropropoxy-3-difluoro-4-fluoro-5-trifluoropentane {l_brace}TPTP{r_brace}. These electrolytes not only have good thermal stability compared to the conventional electrolytes but respectable ionic conductivity. Sandia made 18650 cells successfully completed the formational cycle. The impedance behavior is typical of Li-ion cells.

  19. SEI Formation and Interfacial Stability of a Si Electrode in a LiTDI-Salt Based Electrolyte with FEC and VC Additives for Li-Ion Batteries.

    PubMed

    Lindgren, Fredrik; Xu, Chao; Niedzicki, Leszek; Marcinek, Marek; Gustafsson, Torbjörn; Björefors, Fredrik; Edström, Kristina; Younesi, Reza

    2016-06-22

    An electrolyte based on the new salt, lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI), is evaluated in combination with nano-Si composite electrodes for potential use in Li-ion batteries. The additives fluoroethylene carbonate (FEC) and vinylene carbonate (VC) are also added to the electrolyte to enable an efficient SEI formation. By employing hard X-ray photoelectron spectroscopy (HAXPES), the SEI formation and the development of the active material is probed during the first 100 cycles. With this electrolyte formulation, the Si electrode can cycle at 1200 mAh g(-1) for more than 100 cycles at a coulombic efficiency of 99%. With extended cycling, a decrease in Si particle size is observed as well as an increase in silicon oxide amount. As opposed to LiPF6 based electrolytes, this electrolyte or its decomposition products has no side reactions with the active Si material. The present results further acknowledge the positive effects of SEI forming additives. It is suggested that polycarbonates and a high LiF content are favorable components in the SEI over other kinds of carbonates formed by ethylene carbonate (EC) and dimethyl carbonate (DMC) decomposition. This work thus confirms that LiTDI in combination with the investigated additives is a promising salt for Si electrodes in future Li-ion batteries.

  20. Thermal stability of LiPF 6 salt and Li-ion battery electrolytes containing LiPF 6

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Zhuang, Guorong V.; Ross, Philip N.

    The thermal stability of the neat lithium hexafluorophosphate (LiPF 6) salt and of 1 molal (m) solutions of LiPF 6 in prototypical Li-ion battery solvents was studied with thermogravimetric analysis (TGA) and on-line Fourier transform infrared (FTIR). Pure LiPF 6 salt is thermally stable up to 107 °C in a dry inert atmosphere, and its decomposition path is a simple dissociation producing lithium fluoride (LiF) as solid and PF 5 as gaseous products. In the presence of water (300 ppm) in the carrier gas, its decomposition onset temperature is lowered as a result of direct thermal reaction between LiPF 6 and water vapor to form phosphorous oxyfluoride (POF 3) and hydrofluoric acid (HF). No new products were observed in 1 m solutions of LiPF 6 in ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) by on-line TGA-FTIR analysis. The storage of the same solutions in sealed containers at 85 °C for 300-420 h did not produce any significant quantity of new products as well. In particular, no alkylflurophosphates were found in the solutions after storage at elevated temperature. In the absence of either an impurity like alcohol or cathode active material that may (or may not) act as a catalyst, there is no evidence of thermally induced reaction between LiPF 6 and the prototypical Li-ion battery solvents EC, PC, DMC or EMC.

  1. Morphology and conductivity study of solid electrolyte Li{sub 3}PO{sub 4}

    SciTech Connect

    Prayogi, Lugas Dwi Faisal, Muhamad; Kartini, Evvy Honggowiranto, Wagiyo; Supardi

    2016-02-08

    The comparison between two different methods of synthesize of solid electrolyte Li{sub 3}PO{sub 4} as precursor material for developing lithium ion battery, has been performed. The first method is to synthesize Li{sub 3}PO{sub 4} prepared by wet chemical reaction from LiOH and H{sub 3}PO{sub 4} which provide facile, abundant available resource, low cost, and low toxicity. The second method is solid state reaction prepared by Li{sub 2}CO{sub 3} and NH{sub 4}H{sub 2}PO{sub 4.} In addition, the possible morphology identification of comparison between two different methods will also be discussed. The composition, morphology, and additional identification phase and another compound of Li{sub 3}PO{sub 4} powder products from two different reaction are characterized by SEM, EDS, and EIS. The Li{sub 3}PO{sub 4} powder produced from wet reaction and solid state reaction have an average diameter of 0.834 – 7.81 µm and 2.15 – 17.3 µm, respectively. The density of Li{sub 3}PO{sub 4} prepared by wet chemical reaction is 2.238 gr/cm{sup 3}, little bit lower than the sample prepared by solid state reaction which density is 2.3560 gr/cm{sup 3}. The EIS measurement result shows that the conductivity of Li{sub 3}PO{sub 4} is 1.7 x 10{sup −9} S.cm{sup −1} for wet chemical reaction and 1.8 x 10{sup −10} S.cm{sup −1} for solid state reaction. The conductivity of Li{sub 3}PO{sub 4} is not quite different between those two samples even though they were prepared by different method of synthesize.

  2. Optimized Li-Ion Electrolytes Containing Fluorinated Ester Co-Solvents

    NASA Technical Reports Server (NTRS)

    Prakash, G. K. Surya; Smart, Marshall; Smith, Kiah; Bugga, Ratnakumar

    2010-01-01

    A number of experimental lithium-ion cells, consisting of MCMB (meso-carbon microbeads) carbon anodes and LiNi(0.8)Co(0.2)O2 cathodes, have been fabricated with increased safety and expanded capability. These cells serve to verify and demonstrate the reversibility, low-temperature performance, and electrochemical aspects of each electrode as determined from a number of electrochemical characterization techniques. A number of Li-ion electrolytes possessing fluorinated ester co-solvents, namely trifluoroethyl butyrate (TFEB) and trifluoroethyl propionate (TFEP), were demonstrated to deliver good performance over a wide temperature range in experimental lithium-ion cells. The general approach taken in the development of these electrolyte formulations is to optimize the type and composition of the co-solvents in ternary and quaternary solutions, focusing upon adequate stability [i.e., EC (ethylene carbonate) content needed for anode passivation, and EMC (ethyl methyl carbonate) content needed for lowering the viscosity and widening the temperature range, while still providing good stability], enhancing the inherent safety characteristics (incorporation of fluorinated esters), and widening the temperature range of operation (the use of both fluorinated and non-fluorinated esters). Further - more, the use of electrolyte additives, such as VC (vinylene carbonate) [solid electrolyte interface (SEI) promoter] and DMAc (thermal stabilizing additive), provide enhanced high-temperature life characteristics. Multi-component electrolyte formulations enhance performance over a temperature range of -60 to +60 C. With the need for more safety with the use of these batteries, flammability was a consideration. One of the solvents investigated, TFEB, had the best performance with improved low-temperature capability and high-temperature resilience. This work optimized the use of TFEB as a co-solvent by developing the multi-component electrolytes, which also contain non

  3. Electrolyte decomposition on Li-metal surfaces from first-principles theory

    NASA Astrophysics Data System (ADS)

    Ebadi, Mahsa; Brandell, Daniel; Araujo, C. Moyses

    2016-11-01

    An important feature in Li batteries is the formation of a solid electrolyte interphase (SEI) on the surface of the anode. This film can have a profound effect on the stability and the performance of the device. In this work, we have employed density functional theory combined with implicit solvation models to study the inner layer of SEI formation from the reduction of common organic carbonate electrolyte solvents (ethylene carbonate, propylene carbonate, dimethyl carbonate, and diethyl carbonate) on a Li metal anode surface. Their stability and electronic structure on the Li surface have been investigated. It is found that the CO producing route is energetically more favorable for ethylene and propylene carbonate decomposition. For the two linear solvents, dimethyl and diethyl carbonates, no significant differences are observed between the two considered reduction pathways. Bader charge analyses indicate that 2 e- reductions take place in the decomposition of all studied solvents. The density of states calculations demonstrate correlations between the degrees of hybridization between the oxygen of adsorbed solvents and the upper Li atoms on the surface with the trend of the solvent adsorption energies.

  4. Study on the LLT solid electrolyte thin film with LiPON interlayer intervening between LLT and electrodes

    NASA Astrophysics Data System (ADS)

    Lee, Jong min; Kim, Soo ho; Tak, Yongsug; Yoon, Young Soo

    In this study, a lithium lanthanum titanate (LLT) thin film electrolyte was prepared by RF magnetron sputtering, in order to assess its potential use in solid state thin film batteries. Even though the LLT has high ionic conductivity, it cannot be used alone as a thin film electrolyte since it is chemically unstable when it comes into contact with Li metal and it has a high electronic conductivity. Lithium phosphorous oxynitride (LiPON) is stable when in contact with Li and has an extremely low electronic conductivity. We expected that the LiPON/LLT/LiPON structure would make it possible to use a LLT thin film as a thin film solid electrolyte. In order to prepare this structure, a LiPON thin film was also deposited by RF magnetron sputtering and was deposited for various times (30, 60, 90 and 120 min), in order to determine the optimum thickness ratio between LLT and LiPON. In linear sweep voltammetry measurements, the current hardly flowed in the potential range from 0 to 5.5 V in the blocking electrode and ac impedance was measured for measuring the resistance at LiPON/LLT/LiPON. When only the LLT thin film was deposited, a current of scores of mA flowed in the operating potential range, but when an interlayer of LiPON thin film was deposited for more than 30 min on both sides of the LLT thin film, the current was less than 1 μA. Ionic conductivities of 1.11, 0.82 and 0.48 × 10 -7 S cm -1 were observed for the deposition times of the LiPON thin film of 60, 90 and 120 min, respectively. This result suggests that the LiPON/LLT/LiPON structure might be able to be used as a thin film solid electrolyte if its ionic conductivity could be improved.

  5. Investigating the Dendritic Growth during Full Cell Cycling of Garnet Electrolyte in Direct Contact with Li Metal.

    PubMed

    Aguesse, Frederic; Manalastas, William; Buannic, Lucienne; Lopez Del Amo, Juan Miguel; Singh, Gurpreet; Llordés, Anna; Kilner, John

    2017-02-01

    All-solid-state batteries including a garnet ceramic as electrolyte are potential candidates to replace the currently used Li-ion technology, as they offer safer operation and higher energy storage performances. However, the development of ceramic electrolyte batteries faces several challenges at the electrode/electrolyte interfaces, which need to withstand high current densities to enable competing C-rates. In this work, we investigate the limits of the anode/electrolyte interface in a full cell that includes a Li-metal anode, LiFePO4 cathode, and garnet ceramic electrolyte. The addition of a liquid interfacial layer between the cathode and the ceramic electrolyte is found to be a prerequisite to achieve low interfacial resistance and to enable full use of the active material contained in the porous electrode. Reproducible and constant discharge capacities are extracted from the cathode active material during the first 20 cycles, revealing high efficiency of the garnet as electrolyte and the interfaces, but prolonged cycling leads to abrupt cell failure. By using a combination of structural and chemical characterization techniques, such as SEM and solid-state NMR, as well as electrochemical and impedance spectroscopy, it is demonstrated that a sudden impedance drop occurs in the cell due to the formation of metallic Li and its propagation within the ceramic electrolyte. This degradation process is originated at the interface between the Li-metal anode and the ceramic electrolyte layer and leads to electromechanical failure and cell short-circuit. Improvement of the performances is observed when cycling the full cell at 55 °C, as the Li-metal softening favors the interfacial contact. Various degradation mechanisms are proposed to explain this behavior.

  6. High temperature stable Li-ion battery separators based on polyetherimides with improved electrolyte compatibility

    NASA Astrophysics Data System (ADS)

    l'Abee, Roy; DaRosa, Fabien; Armstrong, Mark J.; Hantel, Moritz M.; Mourzagh, Djamel

    2017-03-01

    We report (electro-)chemically stable, high temperature resistant and fast wetting Li-ion battery separators produced through a phase inversion process using novel polyetherimides (PEI) based on bisphenol-aceton diphthalic anhydride (BPADA) and para-phenylenediamine (pPD). In contrast to previous studies using PEI based on BPADA and meta-phenylenediamine (mPD), the separators reported herein show limited swelling in electrolytes and do not require fillers to render sufficient mechanical strength and ionic conductivity. In this work, the produced 15-25 μm thick PEI-pPD separators show excellent electrolyte compatibility, proven by low degrees of swelling in electrolyte solvents, low contact angles, fast electrolyte wicking and high electrolyte uptake. The separators cover a tunable range of morphologies and properties, leading to a wide range of ionic conductivities as studied by Electrochemical Impedance Spectroscopy (EIS). Dynamic Mechanical Analysis (DMA) demonstrated dimensional stability up to 220 °C. Finally, single layer graphite/lithium nickel manganese cobalt oxide (NMC) pouch cells were assembled using this novel PEI-pPD separator, showing an excellent capacity retention of 89.3% after 1000 1C/2C cycles, with a mean Coulombic efficiency of 99.77% and limited resistance build-up. We conclude that PEI-pPD is a promising new material candidate for high performance separators.

  7. Electrodeposition of polymer electrolyte in nanostructured electrodes for enhanced electrochemical performance of thin-film Li-ion microbatteries

    NASA Astrophysics Data System (ADS)

    Salian, Girish D.; Lebouin, Chrystelle; Demoulin, A.; Lepihin, M. S.; Maria, S.; Galeyeva, A. K.; Kurbatov, A. P.; Djenizian, Thierry

    2017-02-01

    We report that electrodeposition of polymer electrolyte in nanostructured electrodes has a strong influence on the electrochemical properties of thin-film Li-ion microbatteries. Electropolymerization of PMMA-PEG (polymethyl methacrylate-polyethylene glycol) was carried out on both the anode (self-supported titania nanotubes) and the cathode (porous LiNi0.5Mn1.5O4) by cyclic voltammetry and the resulting electrode-electrolyte interface was examined by scanning electron microscopy. The electrochemical characterizations performed by galvanostatic experiments reveal that the capacity values obtained at different C-rates are doubled when the electrodes are completely filled by the polymer electrolyte.

  8. Development of bulk-type all-solid-state lithium-sulfur battery using LiBH{sub 4} electrolyte

    SciTech Connect

    Unemoto, Atsushi Ikeshoji, Tamio; Yasaku, Syun; Matsuo, Motoaki; Nogami, Genki; Tazawa, Masaru; Taniguchi, Mitsugu; Orimo, Shin-ichi

    2014-08-25

    Stable battery operation of a bulk-type all-solid-state lithium-sulfur battery was demonstrated by using a LiBH{sub 4} electrolyte. The electrochemical activity of insulating elemental sulfur as the positive electrode was enhanced by the mutual dispersion of elemental sulfur and carbon in the composite powders. Subsequently, a tight interface between the sulfur-carbon composite and the LiBH{sub 4} powders was manifested only by cold-pressing owing to the highly deformable nature of the LiBH{sub 4} electrolyte. The high reducing ability of LiBH{sub 4} allows using the use of a Li negative electrode that enhances the energy density. The results demonstrate the interface modification of insulating sulfur and the architecture of an all-solid-state Li-S battery configuration with high energy density.

  9. Impedance study of the interface between lithium, polyaniline, lithium-doped MnO 2 and modified poly(ethylene oxide) electrolyte

    NASA Astrophysics Data System (ADS)

    Baochen, Wang; Li, Feng; Yongyao, Xia

    1993-03-01

    Impedance study was carried out for the interfaces between lithium, polyaniline (PAn), lithium-doped MnO 2 and modified poly(ethylene oxide) (PEO) electrolyte under various conditions. The interfacial charge-transfer resistance Rct on PEO/PAn, Rct on PEO/LiMn 2O 4 increase with depth-of-discharge and decrease after the charge of the cell containing modified PEO as electrolyte. The charge-transfer resistance Rct on PEO/PAn is higher than Rct on PEO/LiMn 2O 4 under the same condition, since inserted species and mechanism are different for both cases. In the case of PAn, an additional charge-transfer resistance might be related to the electronic conductivity change in discharge/charge potential range, as it was evident from a voltammetry curve. With increasing cycle numbers, the charge-transfer resistance increases gradually. The impedance results also have shown that at low frequency the diffusion control is dominant in the process of the charge and discharge of Li/PEO/PAn or Li/PEO/LiMn 2O 4 cell. The diffusion coefficients have been calculated from impedance data.

  10. Impedance study of the interfaces between lithium, polyaniline, lithium-doped MnO2 and modified poly(ethylene oxide) electrolyte

    NASA Astrophysics Data System (ADS)

    Wang, Baochen; Feng, Li; Xia, Yongyao

    1993-03-01

    Impedance study was carried out for the interfaces between lithium, polyaniline (PAn), lithium-doped MnO2 and modified poly(ethylene oxide) (PEO) electrolyte under various conditions. The interfacial charge-transfer resistances R(sub ct) on PEO/PAn, R(sub ct) on PEO/LiMn2O increas e with depth-of-discharge and decrease after the charge of the cell containing modified PEO as electrolyte. The charge-transfer resistance R(sub ct) on PEO/PAn is higher than R(sub ct) on PEO/LiMn2O4 under the same condition, since inserted species and mechanism are different for both cases. In the case of PAn, an additional charge-transfer resistance might be related to the electronic conductivity change in discharge/charge potential range, as it was evident from a voltammetry curve. With increasing cycle numbers, the charge-transfer resistance increases gradually. The impedance results also have shown that at low frequency the diffusion control is dominant in the process of the charge and discharge of Li/PEO/PAn or Li/PEO/LiMn2O4 cell. The diffusion coefficients have been calculated from impedance data.

  11. Polymer-ionic liquid ternary systems for Li-battery electrolytes: Molecular dynamics studies of LiTFSI in a EMIm-TFSI and PEO blend

    SciTech Connect

    Costa, Luciano T.

    2015-07-14

    This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li{sup +} coordination and transportation were studied in the ternary electrolyte system, i.e., PEO{sub 16}LiTFSI⋅1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generated significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.

  12. Polymer-ionic liquid ternary systems for Li-battery electrolytes: Molecular dynamics studies of LiTFSI in a EMIm-TFSI and PEO blend.

    PubMed

    Costa, Luciano T; Sun, Bing; Jeschull, Fabian; Brandell, Daniel

    2015-07-14

    This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li(+) coordination and transportation were studied in the ternary electrolyte system, i.e., PEO16LiTFSI⋅1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generated significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.

  13. Polymer-ionic liquid ternary systems for Li-battery electrolytes: Molecular dynamics studies of LiTFSI in a EMIm-TFSI and PEO blend

    NASA Astrophysics Data System (ADS)

    Costa, Luciano T.; Sun, Bing; Jeschull, Fabian; Brandell, Daniel

    2015-07-01

    This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li+ coordination and transportation were studied in the ternary electrolyte system, i.e., PEO16LiTFSIṡ1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generated significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.

  14. Temperature-Dependent Morphology, Magnetic and Optical Properties of Li-Doped MgO

    SciTech Connect

    Myrach, Philipp; Niklas, Nilius; Levchenko, Sergey; Gonchar, Anastasia; Risse, Thomas; Klaus-Peter, Dinse; Boatner, Lynn A; Frandsen, Wiebke; Horn, Raimund; Hans-Joachim, Freund; Schlçgl, Robert; Scheffler, Matthias

    2010-01-01

    Li-doped MgO is a potential catalyst for the oxidative coupling of methane, whereby surface Li+ O centers are suggested to be the chemically active species. To elucidate the role of Li in the MgO matrix, two model systems are prepared and their morphological, optical and magnetic properties as a function of Li doping are investigated. The first is an MgO film deposited on Mo(001) and doped with various amounts of Li, whereas the second is a powder sample fabricated by calcination of Li and Mg precursors in an oxygen atmosphere. Scanning tunneling and transmission electron microscopy are performed to characterize the morphology of both samples. At temperatures above 700 K, Li starts segregating towards the surface and forms irregular Li-rich oxide patches. Above 1050 K, Li desorbs from the MgO surface, leaving behind a characteristic defect pattern. Traces of Li also dissolve into the MgO, as concluded from a distinct optical signature that is absent in the pristine oxide. No electron paramagnetic resonance signal that would be compatible with Li+O centers is detected in the two Li/ MgO samples. Density-functional theory calculations are used to determine the thermodynamic stability of various Li-induced defects in the MgO. The calculations clarify the driving forces for Li segregation towards the MgO surface, but also rationalize the absence of Li+O centers. From the combination of experimental and theoretical results, a detailed picture arises on the role of Li for the MgO properties, which can be used as a starting point to analyze the chemical behavior of the doped oxide in future.

  15. Separators for Li-Ion and Li-Metal Battery Including Ionic Liquid Based Electrolytes Based on the TFSI− and FSI− Anions

    PubMed Central

    Kirchhöfer, Marija; von Zamory, Jan; Paillard, Elie; Passerini, Stefano

    2014-01-01

    The characterization of separators for Li-ion or Li-metal batteries incorporating hydrophobic ionic liquid electrolytes is reported herein. Ionic liquids made of N-butyl-N-methylpyrrolidinium (PYR14+) or N-methoxyethyl-N-methylpyrrolidinium (PYR12O1+), paired with bis(trifluoromethanesulfonyl)imide (TFSI−) or bis(fluorosulfonyl)imide (FSI−) anions, were tested in combination with separators having different chemistries and morphologies in terms of wetting behavior, Gurley and McMullin number, as well as Li/(Separator + Electrolyte) interfacial properties. It is shown that non-functionalized microporous polyolefin separators are poorly wetted by FSI−-based electrolytes (contrary to TFSI−-based electrolytes), while the ceramic coated separator Separion® allows good wetting with all electrolytes. Furthermore, by comparing the lithium solid electrolyte interphase (SEI) resistance evolution at open circuit and during cycling, depending on separator morphologies and chemistries, it is possible to propose a scale for SEI forming properties in the order: PYR12O1FSI > PYR14FSI > PYR14TFSI > PYR12O1TFSI. Finally, the impact the separator morphology is evidenced by the SEI resistance evolution and by comparing Li electrodes cycled using separators with two different morphologies. PMID:25153637

  16. Charge-storage performance of Li/LiFePO4 cells with additive-incorporated ionic liquid electrolytes at various temperatures

    NASA Astrophysics Data System (ADS)

    Wongittharom, Nithinai; Wang, Chueh-Han; Wang, Yi-Chen; Fey, George Ting-Kuo; Li, Hui-Ying; Wu, Tzi-Yi; Lee, Tai-Chou; Chang, Jeng-Kuei

    2014-08-01

    Butylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide (BMP-TFSI) ionic liquid (IL) with LiTFSI solute is used as a base electrolyte for Li/LiFePO4 cells. Three kinds of electrolyte additive, namely vinylene carbonate (VC), gamma-butyrolactone (γ-BL), and propylene carbonate (PC), with various concentrations are introduced. The thermal stability, flammability, and electrochemical properties of the electrolytes are investigated. At 25 °C, the additives (γ-BL is found to be the most effective) can significantly improve the capacity, high-rate performance, and cyclability of the cells. With an increase in temperature to 50 °C, the benefits of the additives gradually become insignificant. At 75 °C, the additives even have adverse effects. At such an elevated temperature, in the plain IL electrolyte (without additives), a LiFePO4 capacity of 152 mAh g-1 is found at 0.1 C. 77% of this capacity can be retained when the rate is increased to 3 C. These values are superior to those found for the additive-incorporated IL and conventional organic electrolytes. Moreover, negligible capacity loss is measured after 100 charge-discharge cycles at 75 °C in the plain IL electrolyte.

  17. Improved Wide Operating Temperature Range of LiNiCoAiO2-based Li-ion Cells with Methyl Propionate-based Electrolytes

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Tomcsi, Michael R.; Hwang, C.; Whitcanack, L. D.; Bugga, Ratnakumar V.; Nagata, Mikito; Visco, Vince; Tsukamoto, Hisashi

    2012-01-01

    Demonstration of wide operating temperature range Li-ion electrolytes Methyl propionate-based wide operating temperature range electrolytes were demonstrated to provide dramatic improvement of the low temperature capability of Quallion prototype Li-ion cells (MCMB-LiNiCoAlO2). Some formulations were observed to deliver over 60% of the room temperature capacity using a 5C rate at - 40oC !! Represents over a 4-fold improvement over the baseline electrolyte system. Demonstrated operational capability of a number of systems over a wide temperature range (-40 to +70 C) Demonstrated reasonably good long term cycle life performance at high temperature (i.e., at +40deg and +50 C) A number of formulations containing electrolytes additives (i.e., FEC, VC, LiBOB, and lithium oxalate) have been shown to have enhanced lithium kinetics at low temperature and promising high temperature resilience. Demonstrated good performance in larger capacity (12 Ah) Quallion Li-ion cells with methyl propionate-based electrolytes. Current efforts focused upon performing life studies and the impact upon low temperature capability.

  18. Nanoscale imaging of fundamental Li battery chemistry: solid-electrolyte interphase formation and preferential growth of lithium metal nanoclusters

    SciTech Connect

    Sacci, Robert L; Black, Jennifer M.; Wisinger, Nina; Dudney, Nancy J.; More, Karren Leslie; Unocic, Raymond R.

    2015-02-23

    The performance characteristics of Li-ion batteries are intrinsically linked to evolving nanoscale interfacial electrochemical reactions. To probe the mechanisms of solid electrolyte interphase formation and Li electrodeposition from a standard battery electrolyte, we use in situ electrochemical scanning transmission electron microscopy for controlled potential sweep-hold electrochemical measurements with simultaneous BF and ADF STEM image acquisition. Through a combined quantitative electrochemical measurement and quantitative STEM imaging approach, based upon electron scattering theory, we show that chemically sensitive ADF STEM imaging can be used to estimate the density of evolving SEI constituents and distinguish contrast mechanisms of Li-bearing components in the liquid cell.

  19. Lithium bis(fluorosulfonyl)imide (LiFSI) as conducting salt for nonaqueous liquid electrolytes for lithium-ion batteries: Physicochemical and electrochemical properties

    NASA Astrophysics Data System (ADS)

    Han, Hong-Bo; Zhou, Si-Si; Zhang, Dai-Jun; Feng, Shao-Wei; Li, Li-Fei; Liu, Kai; Feng, Wen-Fang; Nie, Jin; Li, Hong; Huang, Xue-Jie; Armand, Michel; Zhou, Zhi-Bin

    Lithium bis(fluorosulfonyl)imide (LiFSI) has been studied as conducting salt for lithium-ion batteries, in terms of the physicochemical and electrochemical properties of the neat LiFSI salt and its nonaqueous liquid electrolytes. Our pure LiFSI salt shows a melting point at 145 °C, and is thermally stable up to 200 °C. It exhibits far superior stability towards hydrolysis than LiPF 6. Among the various lithium salts studied at the concentration of 1.0 M (= mol dm -3) in a mixture of ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (3:7, v/v), LiFSI shows the highest conductivity in the order of LiFSI > LiPF 6 > Li[N(SO 2CF 3) 2] (LiTFSI) > LiClO 4 > LiBF 4. The stability of Al in the high potential region (3.0-5.0 V vs. Li +/Li) has been confirmed for high purity LiFSI-based electrolytes using cyclic voltammetry, SEM morphology, and chronoamperometry, whereas Al corrosion indeed occurs in the LiFSI-based electrolytes tainted with trace amounts of LiCl (50 ppm). With high purity, LiFSI outperforms LiPF 6 in both Li/LiCoO 2 and graphite/LiCoO 2 cells.

  20. Effect of Hydrofluoroether Cosolvent Addition on Li Solvation in Acetonitrile-Based Solvate Electrolytes and Its Influence on S Reduction in a Li-S Battery.

    PubMed

    See, Kimberly A; Wu, Heng-Liang; Lau, Kah Chun; Shin, Minjeong; Cheng, Lei; Balasubramanian, Mahalingam; Gallagher, Kevin G; Curtiss, Larry A; Gewirth, Andrew A

    2016-12-21

    Li-S batteries are a promising next-generation battery technology. Due to the formation of soluble polysulfides during cell operation, the electrolyte composition of the cell plays an active role in directing the formation and speciation of the soluble lithium polysulfides. Recently, new classes of electrolytes termed "solvates" that contain stoichiometric quantities of salt and solvent and form a liquid at room temperature have been explored due to their sparingly solvating properties with respect to polysulfides. The viscosity of the solvate electrolytes is understandably high limiting their viability; however, hydrofluoroether cosolvents, thought to be inert to the solvate structure itself, can be introduced to reduce viscosity and enhance diffusion. Nazar and co-workers previously reported that addition of 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) to the LiTFSI in acetonitrile solvate, (MeCN)2-LiTFSI, results in enhanced capacity retention compared to the neat solvate. Here, we evaluate the effect of TTE addition on both the electrochemical behavior of the Li-S cell and the solvation structure of the (MeCN)2-LiTFSI electrolyte. Contrary to previous suggestions, Raman and NMR spectroscopy coupled with ab initio molecular dynamics simulations show that TTE coordinates to Li(+) at the expense of MeCN coordination, thereby producing a higher content of free MeCN, a good polysulfide solvent, in the electrolyte. The electrolytes containing a higher free MeCN content facilitate faster polysulfide formation kinetics during the electrochemical reduction of S in a Li-S cell likely as a result of the solvation power of the free MeCN.

  1. A LiAl/Cl2 battery with a four-component alkali-metal chloride electrolyte

    NASA Astrophysics Data System (ADS)

    Thomas, Daniel L.; Bennion, Douglas N.

    1989-12-01

    A LiAl/Cl2 cell operating at 280 C was investigated. This electrolyte is a mixture of LiC, KCl, RbCl, and CsCl with a eutectic melting point of 258 C. The positive electrode is a gas-diffusion electrode formed by coating one side of a porous carbon electrode with PTCE. The limiting discharge current of the cell was controlled by solid-state diffusion of Li in the LiAl alloy. Polarization of Cl2 electrode was caused by the low cross-sectional area of the electrolyte film compared with the pore cross-sectional area. Deactivation of the positive electrode was caused by impurities, such as Cu(+), in the electrolyte. Mathematical models of the negative and positive electrodes in a LiAl/Cl2 cell with a gas diffusion Cl2 electrode have been formulated. A thin film gas diffusion electrode model was used for the positive electrode, while solid-state diffusion of Li-in alpha-LiAl was assumed to limit the negative electrode and the cell current. Comparison of the experimental results with the model indicate that the diffusivity of Li in alpha-LiAl is of the order of 10 to the -12 sq cm/sec.

  2. Novel Organic-Inorganic Hybrid Electrolyte to Enable LiFePO4 Quasi-Solid-State Li-Ion Batteries Performed Highly around Room Temperature.

    PubMed

    Tan, Rui; Gao, Rongtan; Zhao, Yan; Zhang, Mingjian; Xu, Junyi; Yang, Jinlong; Pan, Feng

    2016-11-16

    A novel type of organic-inorganic hybrid polymer electrolytes with high electrochemical performances around room temperature is formed by hybrid of nanofillers, Y-type oligomer, polyoxyethylene and Li-salt (PBA-Li), of which the Tg and Tm are significantly lowered by blended heterogeneous polyethers and embedded nanofillers with benefit of the dipole modification to achieve the high Li-ion migration due to more free-volume space. The quasi-solid-state Li-ion batteries based on the LiFePO4/15PBA-Li/Li-metal cells present remarkable reversible capacities (133 and 165 mAh g(-1) @0.2 C at 30 and 45 °C, respectively), good rate ability and stable cycle performance (141.9 mAh g(-1) @0.2 C at 30 °C after 150 cycles).

  3. Neutron scattering study on cathode LiMn2O4 and solid electrolyte 5(Li2O)(P2O5)

    NASA Astrophysics Data System (ADS)

    Kartini, E.; Putra, Teguh P.; Jahya, A. K.; Insani, A.; Adams, S.

    2014-09-01

    Neutron scattering is very important technique in order to investigate the energy storage materials such as lithium-ion battery. The unique advantages, neutron can see the light atoms such as Hydrogen, Lithium, and Oxygen, where those elements are negligible by other corresponding X-ray method. On the other hand, the energy storage materials, such as lithium ion battery is very important for the application in the electric vehicles, electronic devices or home appliances. The battery contains electrodes (anode and cathode), and the electrolyte materials. There are many challenging to improve the existing lithium ion battery materials, in order to increase their life time, cyclic ability and also its stability. One of the most scientific challenging is to investigate the crystal structure of both electrode and electrolyte, such as cathodes LiCoO2, LiMn2O4 and LiFePO4, and solid electrolyte Li3PO4. Since all those battery materials contain Lithium ions and Oxygen, the used of neutron scattering techniques to study their structure and related properties are very important and indispensable. This article will review some works of investigating electrodes and electrolytes, LiMn2O4 and 5(Li2O)(P2O5), by using a high resolution powder diffraction (HRPD) at the multipurpose research reactor, RSG-Sywabessy of the National Nuclear Energy Agency (BATAN), Indonesia.

  4. Fast Li ion dynamics in the solid electrolyte Li7 P3 S11 as probed by (6,7) Li NMR spin-lattice relaxation.

    PubMed

    Wohlmuth, Dominik; Epp, Viktor; Wilkening, Martin

    2015-08-24

    The development of safe and long-lasting all-solid-state batteries with high energy density requires a thorough characterization of ion dynamics in solid electrolytes. Commonly, conductivity spectroscopy is used to study ion transport; much less frequently, however, atomic-scale methods such as nuclear magnetic resonance (NMR) are employed. Here, we studied long-range as well as short-range Li ion dynamics in the glass-ceramic Li7 P3 S11 . Li(+) diffusivity was probed by using a combination of different NMR techniques; the results are compared with those obtained from electrical conductivity measurements. Our NMR relaxometry data clearly reveal a very high Li(+) diffusivity, which is reflected in a so-called diffusion-induced (6) Li NMR spin-lattice relaxation peak showing up at temperatures as low as 313 K. At this temperature, the mean residence time between two successful Li jumps is in the order of 3×10(8) s(-1) , which corresponds to a Li(+) ion conductivity in the order of 10(-4) to 10(-3) S cm(-1) . Such a value is in perfect agreement with expectations for the crystalline but metastable glass ceramic Li7 P3 S11 . In contrast to conductivity measurements, NMR analysis reveals a range of activation energies with values ranging from 0.17 to 0.26 eV, characterizing Li diffusivity in the bulk. In our case, through-going Li ion transport, when probed by using macroscopic conductivity spectroscopy, however, seems to be influenced by blocking grain boundaries including, for example, amorphous regions surrounding the Li7 P3 S11 crystallites. As a result of this, long-range ion transport as seen by impedance spectroscopy is governed by an activation energy of approximately 0.38 eV. The findings emphasize how surface and grain boundary effects can drastically affect long-range ionic conduction. If we are to succeed in solid-state battery technology, such effects have to be brought under control by, for example, sophisticated densification or through the preparation

  5. Preparation of Li2S-P2S5 solid electrolyte from N-methylformamide solution and application for all-solid-state lithium battery

    NASA Astrophysics Data System (ADS)

    Teragawa, Shingo; Aso, Keigo; Tadanaga, Kiyoharu; Hayashi, Akitoshi; Tatsumisago, Masahiro

    2014-02-01

    Electrode-solid electrolyte composite materials for all-solid-state lithium batteries were prepared by coating of the Li2S-P2S5 solid electrolyte onto LiCoO2 particles using a N-methylformamide (NMF) solution of 80Li2S·20P2S5 (mol%) solid electrolyte. SEM and EDX analysis showed that the Li2S-P2S5 solid electrolyte was uniformly coated on LiCoO2 particles. The all-solid-state cell using the LiCoO2 particles coated with the solid electrolyte showed higher charge-discharge capacity than the cells using uncoated LiCoO2 particles.

  6. Solvothermal synthesis of Fe-doping LiMnPO4 nanomaterials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Hu, Lingjun; Qiu, Bao; Xia, Yonggao; Qin, Zhihong; Qin, Laifen; Zhou, Xufeng; Liu, Zhaoping

    2014-02-01

    The Fe-doping LiMnPO4 (LiMn1-xFexPO4, x ≤ 0.5) nanomaterials are solvothermally synthesized in a mixed solvent of water and polyethylene glycol (PEG). The particle morphology can be controlled simply by adjusting the pH values of precursor suspensions. Electrochemical test shows that LiMn0.9Fe0.1PO4 nanoplates with a thickness of 20-30 nm could deliver the largest discharge capacity, which is attributed to the fast Li+ diffusion in the diffusion path of [010] crystallographic axis along the short radial direction of the nanoplates. It is demonstrated that Fe doping could significantly increase the initial reversible capacity, cycle performance and rate capability. The first discharge capacities of Fe-doped LiMnPO4 are all above 150 mAh g-1 at the discharge rate of 0.05 C. Especially, LiMn0.5Fe0.5PO4 delivers 100% capacity retention with the reversible capacity of 147 mAh g-1 at the discharge rate of 1 C, and losses only about 23.4% capacity with the discharge rate varying from 0.1 C to 5 C. The variation of energy density predicts that LiMn0.5Fe0.5PO4 shows the potential application for high-power devices.

  7. Optically pumped cerium-doped LiSrAlF{sub 6} and LiCaAlF{sub 6}

    DOEpatents

    Marshall, C.D.; Payne, S.A.; Krupke, W.F.

    1996-05-14

    Ce{sup 3+}-doped LiSrAlF{sub 6} crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF{sub 6} with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF{sub 6} type of chemical formula, e.g. Ce-doped LiCaAlF{sub 6} and LiSrGaF{sub 6}, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator. 10 figs.

  8. Optically pumped cerium-doped LiSrAlF.sub.6 and LiCaAlF.sub.6

    DOEpatents

    Marshall, Christopher D.; Payne, Stephen A.; Krupke, William F.

    1996-01-01

    Ce.sup.3+ -doped LiSrAlF.sub.6 crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF.sub.6 with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF.sub.6 type of chemical formula, e.g. Ce-doped LiCaAlF.sub.6 and LiSrGaF.sub.6, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator.

  9. UV-cured methacrylic membranes as novel gel-polymer electrolyte for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Nair, J. R.; Gerbaldi, C.; Meligrana, G.; Bongiovanni, R.; Bodoardo, S.; Penazzi, N.; Reale, P.; Gentili, V.

    In this paper, we report the synthesis and characterisation of novel methacrylic based polymer electrolyte membranes for lithium batteries. The method adopted for preparing the solid polymer electrolyte was the UV-curing process, which is well known for being easy, low cost, fast and reliable. It consists of a free radical photo polymerisation of poly-functional monomers: Bisphenol A ethoxylate (15 EO/phenol) dimethacrylate (BEMA) was chosen, as it can readily form flexible 3D networks and has long poly-ethoxy chains which can enhance the movement of Li +-ions inside the polymer matrix. The preliminary results reported here refer to systems where LiPF 6 solutions swelled the preformed polymer membranes. The tests on the conductivity, stability and cyclability of the membranes put in evidence the importance of the polymerisation in presence of mono-methacrylates acting as reactive diluents. Good values of ionic conductivity have been found, especially at ambient temperature. Much better results can be expected by choosing an appropriate mono-methacrylate to modify the polymeric membrane properties and by modifying the methodology of Li +-ions incorporation inside the polymer matrix.

  10. Effect of Eutectic Concentration on Conductivity in PEO:LiX Based Solid Polymer Electrolytes

    NASA Astrophysics Data System (ADS)

    Zhan, Pengfei; Ganapatibhotla, Lalitha; Maranas, Janna

    Polyethylene oxide (PEO) and lithium salt based solid polymer electrolytes (SPEs) have been widely proposed as a substitution for the liquid electrolyte in Li-ion batteries. As salt concentration varies, these systems demonstrate rich phase behavior. Conductivity as a function of salt concentration has been measured for decades and various concentration dependences have been observed. A PEO:LiX mixture can have one or two conductivity maximums, while some mixtures with salt of high ionic strength will have higher conductivity as the salt concentration decrease. The factors that affect the conductivity are specific for each sample. The universal factor that affects conductivity is still not clear. In this work, we measured the conductivity of a series of PEO:LiX mixtures and statistical analysis shows conductivity is affected by the concentration difference from the eutectic concentration (Δc). The correlation with Δc is stronger than the correlation with glass transition temperature. We believe that at the eutectic concentration, during the solidification process, unique structures can form which aid conduction. Currently at Dow Chemical.

  11. Enhanced cycling performance of a Li metal anode in a dimethylsulfoxide-based electrolyte using highly concentrated lithium salt for a lithium-oxygen battery

    NASA Astrophysics Data System (ADS)

    Togasaki, Norihiro; Momma, Toshiyuki; Osaka, Tetsuya

    2016-03-01

    Stable charge-discharge cycling behavior for a lithium metal anode in a dimethylsulfoxide (DMSO)-based electrolyte is strongly desired of lithium-oxygen batteries, because the Li anode is rapidly exhausted as a result of side reactions during cycling in the DMSO solution. Herein, we report a novel electrolyte design for enhancing the cycling performance of Li anodes by using a highly concentrated DMSO-based electrolyte with a specific Li salt. Lithium nitrate (LiNO3), which forms an inorganic compound (Li2O) instead of a soluble product (Li2S) on a lithium surface, exhibits a >20% higher coulombic efficiency than lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium perchlorate, regardless of the loading current density. Moreover, the stable cycling of Li anodes in DMSO-based electrolytes depends critically on the salt concentration. The highly concentrated electrolyte 4.0 M LiNO3/DMSO displays enhanced and stable cycling performance comparable to that of carbonate-based electrolytes, which had not previously been achieved. We suppose this enhancement is due to the absence of free DMSO solvent in the electrolyte and the promotion of the desolvation of Li ions on the solid electrolyte interphase surface, both being consequences of the unique structure of the electrolyte.

  12. Doped carbon-sulfur species nanocomposite cathode for Li--S batteries

    DOEpatents

    Wang, Donghai; Xu, Tianren; Song, Jiangxuan

    2015-12-29

    We report a heteroatom-doped carbon framework that acts both as conductive network and polysulfide immobilizer for lithium-sulfur cathodes. The doped carbon forms chemical bonding with elemental sulfur and/or sulfur compound. This can significantly inhibit the diffusion of lithium polysulfides in the electrolyte, leading to high capacity retention and high coulombic efficiency.

  13. Transition from half metal to semiconductor in Li doped g-C4N3

    NASA Astrophysics Data System (ADS)

    Hashmi, Arqum; Hu, Tao; Hong, Jisang

    2014-03-01

    We have investigated the structural and magnetic properties of Li doped graphitic carbon nitride (g-C4N3) using the van der Waals density functional theory. A free standing g-C4N3 was known to show a half metallic state with buckling geometry, but this feature completely disappears in the presence of Li doping. Besides this structural modification, very interestingly, we have obtained that the Li doped g-C4N3 shows dramatic change in its electronic structure. Both ferromagnetic and nonmagnetic states are almost degenerated in one Li atom doped system. However, the transition from half metallic state to semiconductor is observed with further increase of Li concentration and the calculated energy gap is 1.97 eV. We found that Li impurity plays as a donor element and charge transfer from the Li atom to neighboring N atoms induces a band gap. Overall, we have observed that the electronic and magnetic properties of g-C4N3 are substantially modified by Li doping.

  14. A study of tetrabromobisphenol A (TBBA) as a flame retardant additive for Li-ion battery electrolytes

    NASA Astrophysics Data System (ADS)

    Belov, Dmitry G.; Shieh, D. T.

    2014-02-01

    Electrochemical behavior and flammability of tetrabromobisphenol A (TBBA)-mixed electrolyte solutions are investigated using 1 mol L-1 LiPF6-EC:EMC (1:2 vol.%) with 0 wt.% (reference electrolyte) and 1-3 wt.% of TBBA. The cycling performance (at room and elevated temperature) and rate capability of the 18650 cell (LiMn2O4:Li(Ni1/3Co1/3Mn1/3)O2 (8:2)/Li4Ti5O12) cell containing TBBA-mixed electrolyte is similar to that of cell containing the reference electrolyte. A detailed analysis of the surface on both the anode and the cathode electrodes via X-ray photoelectron spectroscopy (XPS) indicated that the cathode electrode contains more Br components than the anode electrode. Within the first few cycles, on the positive electrode, we observe competing redox processes between the cathode material containing Mn and TBBA, which generate hydroxy radicals and other by-products. This process and the electrochemical reductive decomposition of TBBA to HBr, Br2 and bisphenole A are responsible for the increased flame retardant properties of the electrolyte containing TBBA. Safety tests were performed using an 18650 cell showed that even 1 wt.% of TBBA in the electrolyte significantly reduces cell flammability.

  15. Synthesis of Ionic Liquid Based Electrolytes, Assembly of Li-ion Batteries, and Measurements of Performance at High Temperature.

    PubMed

    Lin, Xinrong; Chapman Varela, Jennifer; Grinstaff, Mark W

    2016-12-20

    The chemical instability of the traditional electrolyte remains a safety issue in widely used energy storage devices such as Li-ion batteries. Li-ion batteries for use in devices operating at elevated temperatures require thermally stable and non-flammable electrolytes. Ionic liquids (ILs), which are non-flammable, non-volatile, thermally stable molten salts, are an ideal replacement for flammable and low boiling point organic solvent electrolytes currently used today. We herein describe the procedures to: 1) synthesize mono- and di-phosphonium ionic liquids paired with chloride or bis(trifluoromethane)sulfonimide (TFSI) anions; 2) measure the thermal properties and stability of these ionic liquids by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA); 3) measure the electrochemical properties of the ionic liquids by cyclic voltammetry (CV); 4) prepare electrolytes containing lithium bis(trifluoromethane)sulfonamide; 5) measure the conductivity of the electrolytes as a function of temperature; 6) assemble a coin cell battery with two of the electrolytes along with a Li metal anode and LiCoO2 cathode; and 7) evaluate battery performance at 100 °C. We additionally describe the challenges in execution as well as the insights gained from performing these experiments.

  16. Novel electrolyte mixtures based on dimethyl sulfone, ethylene carbonate and LiPF6 for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Hofmann, Andreas; Hanemann, Thomas

    2015-12-01

    In this study, novel electrolyte mixtures for Li-ion cells are presented which are composed of ethylene carbonate/dimethyl sulfone (80:20 wt./wt.) as a solvent mixture and LiPF6, lithium bis(oxalato)borate and lithium difluoro(oxalato)borate as conducting salts. The main advantages of the solvent mixture are high flash points of >140 °C which enhance the intrinsic safety of Li-ion cells while maintaining good cell performance above 0-5 °C. The movability of the lithium ions in the electrolyte is investigated via programmed current derivative chronopotentiometry. It is found that pure electrolyte properties cannot necessarily predict the electrolyte behavior in real Li-ion cells but the complex interplay between electrolytes, electrode materials and separators has to be taken into account. Using the newly developed electrolytes, it is possible to achieve C-rates up to 1.5C with >80% of the initial specific discharge capacity (25 °C). Within 200 cycles during one month in cell tests (C||NMC) it is proven that the retention of the specific capacity is >98% of the third discharge cycle in dependence of the conducting salt.

  17. DMAC and NMP as Electrolyte Additives for Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, Marshall; Bugga, Ratnakumar; Lucht, Brett

    2008-01-01

    Dimethyl acetamide (DMAC) and N-methyl pyrrolidinone (NMP) have been found to be useful as high-temperature-resilience-enhancing additives to a baseline electrolyte used in rechargeable lithium-ion electrochemical cells. The baseline electrolyte, which was previously formulated to improve low-temperature performance, comprises LiPF6 dissolved at a concentration of 1.0 M in a mixture comprising equal volume proportions of ethylene carbonate, diethyl carbonate, and dimethyl carbonate. This and other electrolytes comprising lithium salts dissolved in mixtures of esters (including alkyl carbonates) have been studied in continuing research directed toward extending the lower limits of operating temperatures and, more recently, enhancing the high-temperature resilience of such cells. This research at earlier stages, and the underlying physical and chemical principles, were reported in numerous previous NASA Tech Briefs articles. Although these electrolytes provide excellent performance at low temperatures (typically as low as -40 C), when the affected Li-ion cells are subjected to high temperatures during storage and cycling, there occur irreversible losses of capacity accompanied by power fade and deterioration of low-temperature performance. The term "high-temperature resilience" signifies, loosely, the ability of a cell to resist such deterioration, retaining as much as possible of its initial charge/discharge capacity during operation or during storage in the fully charged condition at high temperature. For the purposes of the present development, a temperature is considered to be high if it equals or exceeds the upper limit (typically, 30 C) of the operating-temperature range for which the cells in question are generally designed.

  18. Anodic polymerization of vinyl ethylene carbonate in Li-Ion battery electrolyte

    SciTech Connect

    Chen, Guoying; Zhuang, Guorong V.; Richardson, Thomas J.; Gao, Liu; Ross Jr., Philip N.

    2005-02-28

    A study of the anodic oxidation of vinyl ethylene carbonate (VEC) was conducted with post-mortem analysis of reaction products by ATR-FTIR and gel permeation chromatography (GPC). The half-wave potential (E1/2) for oxidation of VEC is ca. 3.6 V producing a resistive film on the electrode surface. GPC analysis of the film on a gold electrode produced by anodization of a commercial Li-ion battery electrolyte containing 2 percent VEC at 4.1 V showed the presence of a high molecular weight polymer. IR analysis indicated polycarbonate with alkyl carbonate rings linked by aliphatic methylene and methyl branches.

  19. Novel Concentrated Li[(FSO2)(n-C4F9SO2)N]-Based Ether Electrolyte for Superior Stability of Metallic Lithium Anode.

    PubMed

    Fang, Zheng; Ma, Qiang; Liu, Pin; Ma, Jie; Hu, Yong-Sheng; Zhou, Zhibin; Li, Hong; Huang, Xuejie; Chen, Liquan

    2017-02-08

    Lithium (fluorosulfonyl)(n-nonafluorobutanesulfonyl)imide [Li[(FSO2)(n-C4F9SO2)N] (LiFNFSI)] is investigated as a conducting salt, which can form a relatively stable solid-electrolyte-interphase film in concentrated ether electrolyte to achieve favorable protection for lithium metal anodes. Li|Cu and Li|Li cells with concentrated LiFNFSI-based electrolyte have been demonstrated to display high average Coulombic efficiency (≈97%) and excellent cycling stability (over 1,000 h) of metallic lithium anodes, compared to concentrated lithium bis(trifluoromethanesulfonyl)imide [Li[N(SO2CF3)2] (LiTFSI)]-based electrolyte. The morphologies and compositions of the lithium-metal anode surface are also comparatively analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Moreover, superior electrochemical performance in the concentrated LiFNFSI-based electrolyte for Li|LiFePO4 cells is also presented herein. These results indicate that concentrated LiFNFSI-based electrolyte is a promising candidate for metallic lithium rechargeable batteries.

  20. Neutron Fading Characteristics of Copper Doped Lithium Fluoride (LiF: MCP) Thermoluminescent Dosimeters (TLDs)

    DTIC Science & Technology

    2008-05-21

    Fading Characteristics of Copper-Doped Lithium Fluoride (LiF: MCP) Thermoluminescent Dosimeters (TLDs)" Name of Candidate: L T Jeffrey A. Delzer Master...Lithium Fluoride Thermoluminescent Dosimeters beyond brief excerpts is with the permission of the copyright owner, and will save and hold harmless...Thesis: Author: Thesis directed by: ABSTRACT "Neutron Fading Characteristics of Copper-Doped Lithium Fluoride (LiF: MCP) Thermoluminescent

  1. Is the Solid Electrolyte Interphase an Extra-Charge Reservoir in Li-Ion Batteries?

    PubMed

    Rezvani, S Javad; Gunnella, Roberto; Witkowska, Agnieszka; Mueller, Franziska; Pasqualini, Marta; Nobili, Francesco; Passerini, Stefano; Cicco, Andrea Di

    2017-02-08

    Advanced metal oxide electrodes in Li-ion batteries usually show reversible capacities exceeding the theoretically expected ones. Despite many studies and tentative interpretations, the origin of this extra-capacity is not assessed yet. Lithium storage can be increased through different chemical processes developing in the electrodes during charging cycles. The solid electrolyte interface (SEI), formed already during the first lithium uptake, is usually considered to be a passivation layer preventing the oxidation of the electrodes while not participating in the lithium storage process. In this work, we combine high resolution soft X-ray absorption spectroscopy with tunable probing depth and photoemission spectroscopy to obtain profiles of the surface evolution of a well-known prototype conversion-alloying type mixed metal oxide (carbon coated ZnFe2O4) electrode. We show that a partially reversible layer of alkyl lithium carbonates is formed (∼5-7 nm) at the SEI surface when reaching higher Li storage levels. This layer acts as a Li reservoir and seems to give a significant contribution to the extra-capacity of the electrodes. This result further extends the role of the SEI layer in the functionality of Li-ion batteries.

  2. Y-doped Li8ZrO6: A Li-Ion Battery Cathode Material with High Capacity.

    PubMed

    Huang, Shuping; Wilson, Benjamin E; Wang, Bo; Fang, Yuan; Buffington, Keegan; Stein, Andreas; Truhlar, Donald G

    2015-09-02

    We study--experimentally and theoretically--the energetics, structural changes, and charge flows during the charging and discharging processes for a new high-capacity cathode material, Li8ZrO6 (LZO), which we study both pure and yttrium-doped. We quantum mechanically calculated the stable delithiated configurations, the delithiation energy, the charge flow during delithiation, and the stability of the delithiated materials. We find that Li atoms are easier to extract from tetrahedral sites than octahedral ones. We calculate a large average voltage of 4.04 eV vs Li/Li(+) for delithiation of the first Li atom in a primitive cell, which is confirmed by galvanostatic charge/discharge cycling data. Energy calculations indicate that topotactic delithiation is kinetically favored over decomposition into Li, ZrO2, and O2 during the charging process, although the thermodynamic energy of the topotactic reaction is less favorable. When one or two lithium atoms are extracted from a primitive cell of LZO, its volume and structure change little, whereas extraction of the third lithium greatly distorts the layered structure. The Li6ZrO6 and Li5ZrO6 delithiation products can be thermodynamically metastable to release of O2. Experimentally, materials with sufficiently small particle size for efficient delithiation and relithiation were achieved within an yttrium-doped LZO/carbon composite cathode that exhibited an initial discharge capacity of at least 200 mAh/g over the first 10 cycles, with 142 mAh/g maintained after 60 cycles. Computations predict that during the charging process, the oxygen ion near the Li vacancy is oxidized for both pure LZO and yttrium-doped LZO, which leads to a small-polaron hole.

  3. Detonation nanodiamond introduced into samarium doped ceria electrolyte improving performance of solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Pei, Kai; Li, Hongdong; Zou, Guangtian; Yu, Richeng; Zhao, Haofei; Shen, Xi; Wang, Liying; Song, Yanpeng; Qiu, Dongchao

    2017-02-01

    A novel electrolyte materials of introducing detonation nanodiamond (DNDs) into samarium doped ceria (SDC) is reported here. 1%wt. DNDs doping SDC (named SDC/ND) can enlarge the electrotyle grain size and change the valence of partial ceria. DNDs provide the widen channel to accelerate the mobility of oxygen ions in electrolyte. Larger grain size means that oxygen ions move easier in electrolyte, it can also reduce the alternating current (AC) impedance spectra of internal grains. The lower valence of partial Ce provides more oxygen vacancies to enhance mobility rate of oxygen ions. Hence all of them enhance the transportation of oxygen ions in SDC/ND electrolyte and the OCV. Ultimately the power density of SOFC can reach 762 mw cm-2 at 800 °C (twice higher than pure SDC, which is 319 mw cm-2 at 800 °C), and it remains high power density in the intermediate temperature (600-800 °C). It is relatively high for the electrolyte supported (300 μm) cells.

  4. Enhanced luminescence of Gd2O3:Eu3+ thin-film phosphors by Li doping

    NASA Astrophysics Data System (ADS)

    Yi, Soung-soo; Bae, Jong Seong; Shim, Kyoo Sung; Jeong, Jung Hyun; Park, Jung-Chul; Holloway, P. H.

    2004-01-01

    Gd2O3:Eu3+ and Li-doped Gd2O3:Eu3+ luminescent thin films have been grown on Al2O3 (0001) substrates using pulsed-laser deposition. The films grown under different deposition conditions show different microstructural and luminescent characteristics. Both cubic and monoclinic crystalline structures were observed in Gd2O3:Eu3+ films, but only the cubic crystalline structure was observed for Li-doped Gd2O3:Eu3+ films grown under certain condition. The photoluminescence (PL) brightness data obtained from Li-doped Gd2O3:Eu3+ films indicate that sapphire is a promising substrate for growth of high-quality Li-doped Gd2O3:Eu3+ thin-film red phosphor. In particular, incorporation of Li+ ions into the Gd2O3 lattice can induce a remarkable increase of PL. The highest emission intensity was observed with LiF-doped Gd1.84Li0.08Eu0.08O3, whose brightness was a factor of 2.3 larger than that from Gd2O3:Eu3+ films. This phosphor is promising for applications in flat-panel displays.

  5. Polyfluorinated boron cluster-based salts: A new electrolyte for application in Li 4Ti 5O 12/LiMn 2O 4 rechargeable lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Ionica-Bousquet, C. M.; Muñoz-Rojas, D.; Casteel, W. J.; Pearlstein, R. M.; GirishKumar, G.; Pez, G. P.; Palacín, M. R.

    The cycling performance of Li 4Ti 5O 12 and LiMn 2O 4 electrode materials has been studied in half and complete Li-ion cells with two new polyfluorinated boron cluster lithium salts (Li 2B 12F xH 12- x) as the electrolytes. The results were compared with those obtained for the standard electrolyte, 1 M LiPF 6 dissolved in ethylene carbonate and dimethyl carbonate (EC:DMC; 1:1, v/v). Three different technologies were employed for electrode fabrication: powder mixture, self-standing films and films deposited on the current collector. The latter exhibit the most interesting behavior and best performance. Cells assembled using the new electrolyte salts show excellent reversibility, coulombic efficiency, rate capability and cyclability comparable with the standard electrolyte. These features confirm the feasibility of using these polyfluorinated boron cluster-based salts as new stable Li-ion battery electrolytes.

  6. Study of microstructural characterization and ionic conductivity of a chemical-covalent polyether-siloxane hybrid doped with LiClO4.

    PubMed

    Liang, Wuu-Jyh; Chen, Ying-Pin; Wu, Chien-Pang; Kuo, Ping-Lin

    2005-12-29

    The chemical-covalent polyether-siloxane hybrids (EDS) doped with various amounts of LiClO4 salt were characterized by FT-IR, DSC, TGA, and solid-state NMR spectra as well as impedance measurements. These observations indicate that different types of complexes by the interactions of Li+ and ClO4- ions are formed within the hybrid host, and the formation of transient cross-links between Li+ ions and ether oxygens results in the increase in T(g) of polyether segments and the decrease in thermal stability of hybrid electrolyte. Initially a cation complexation dominated by the oxirane-cleaved cross-link site and PEO block is present, and after the salt-doped level of O/Li+ = 20, the complexation through the PPO block becomes more prominent. Moreover, a significant degree of ionic association is examined in the polymer-salt complexes at higher salt uptakes. A VTF-like temperature dependence of ionic conductivity is observed in all of the investigated salt concentrations, implying that the diffusion of charge carrier is assisted by the segmental motions of the polymer chains. The behavior of ion transport in these hybrid electrolytes is further correlated with the interactions between ions and polymer host.

  7. Treatment of electrochemical cell components with lithium tetrachloroaluminate (LiAlCl.sub.4) to promote electrolyte wetting

    DOEpatents

    Eberhart, James G.; Battles, James E.

    1980-01-01

    Electrochemical cell components such as interelectrode separators, retaining screens and current collectors are contacted with lithium tetrachloroaluminate prior to contact with molten electrolytic salt to improve electrolyte wetting. The LiAlCl.sub.4 can be applied in powdered, molten or solution form but, since this material has a lower melting point than the electrolytic salt used in high-temperature cells, the powdered LiAlCl.sub.4 forms a molten flux prior to contact by the molten electrolyte when both materials are initially provided in solid form. Components of materials such as boron nitride and other materials which are difficult to wet with molten salts are advantageously treated by this process.

  8. Transport properties of the solid polymer electrolyte system P(EO){sub n}LiTFSI

    SciTech Connect

    Edman, L.; Doeff, M.M.; Ferry, A.; Kerr, J.; De Jonghe, L.C.

    2000-04-20

    Values for the lithium ion transference number ({tau}{sub +}{sup 0}) are reported for the solid polymer electrolyte system poly(ethylene oxide) (PEO) complexed with Li(CF{sub 3}SO{sub 2}){sub 2}N (LiTFSI). {tau}{sub +}{sup 0} ranges from 0.17 {+-} 0.17 to 0.60 {+-} 0.03 in the salt concentration (c) region of 742 to 2,982 mol/m{sup 3} at 85 C. The concentration dependence of {tau}{sub +}{sup 0} and the molar ionic conductivity ({Lambda}) are shown to be in good agreement with a free volume approach over the salt-rich composition range investigated. The present {tau}{sub +}{sup 0} results were obtained using an electrochemical technique based on concentrated solution theory. This experimentally straightforward method is herein demonstrated to give accurate results for a highly concentrated SPE system, without relying on any dubious simplifications regarding the state of the electrolyte.

  9. Preparation and characterization of PVC-LiClO 4 based composite polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Ahmad, A.; Rahman, M. Y. A.; Su'ait, M. S.

    2008-11-01

    The preparation of PVC-LiClO 4 based composite polymer electrolyte was carried out to study the effect of ceramic fillers such as ZnO, TiO 2 and Al 2O 3 on the room temperature conductivity. The samples were tested using impedance spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The samples were prepared with different percentage (%) by weight of ceramic filler. The highest ionic conductivity achieved was 3.7×10 -7 S cm -1 for the sample prepared with 20% of ZnO. The glass transition temperature decreases with the fillers concentration due to the increasing amorphous state. While, the decomposition temperature increases with the increase in the fillers content. Both of these thermal properties influence the enhancement of the conductivity value. The morphology of the samples shows the even distribution of the ceramic filler in the samples however the filler starts to agglomerate in the sample at higher concentration of filler. In conclusion, the addition of ceramic filler improves the ionic conductivity of PVC-LiCIO 4 composite polymer electrolyte.

  10. Electrolytes with Improved Safety Developed for High Specific Energy Li-Ion Cells with Si-Based Anodes

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Krause, F. C.; Hwang, C.; Soler, J.; West, W. C.; Ratnakumar, B. V.; Prakash, G. K. S.

    2012-01-01

    A number of electrolyte formulations that have improved safety characteristics have been developed for use with high capacity silicon-based anodes. To improve the compatibility with Si-based anodes, a number of technical approaches have been employed, including: (1) the use of mono-fluoroethylene carbonate (FEC) in conjunction with, or in lieu of, ethylene carbonate (EC), (2) the use of high proportions of fluorinated co-solvents, (3) the use of vinylene carbonate (VC) to stabilize the Si/C electrode, and (4) the use of lithium bis(oxalato)borate (LiBOB) to improve the compatibility of the electrolyte when Si/C electrodes are used in conjunction with high voltage cathodes. Candidate electrolytes were studied in Li/Si-C and Si-C/ Li(MnNiCo)O2 (NMC) coin cells, as well as in larger Si-C/NMC three-electrode cells equipped with lithium reference electrodes. In summary, many electrolytes that contain triphenyl phosphate (TPP), which is used as a flame retardant additive up to concentrations of 15 volume percent, and possess FEC as a co-solvent have been demonstrated to outperform the all-carbonate baseline electrolytes when evaluated in Si-C/ Li(MnNiCo)O2 cells.

  11. Improved electrical properties of Fe nanofiller impregnated PEO + PVP:Li+ blended polymer electrolytes for lithium battery applications

    NASA Astrophysics Data System (ADS)

    Naveen Kumar, K.; Saijyothi, K.; Kang, Misook; Ratnakaram, Y. C.; Hari Krishna, K.; Jin, Dahee; Lee, Yong Min

    2016-07-01

    Solid polymer-blended electrolyte films of polyethylene oxide (PEO) + polyvinyl pyrrolidone (PVP)/lithium perchlorate embedded with iron (Fe) nanofiller in different concentrations have been synthesized by a solution casting method. The semicrystalline nature of these polymer electrolyte films has been confirmed from their XRD profiles. Polymer complex formation and ion-polymer interactions are systematically studied by FTIR and laser Raman spectral analysis. Surface morphological studies are carried out from SEM analysis. Dispersed Fe nanofiller size evaluation study has been carried out using transmission electron microscopy (TEM). In order to evaluate the thermal stability, decomposition temperature, and thermogravimetric dynamics, we carried out the TG/DTA measurement. Upon addition of Fe nanofiller to the PEO + PVP/Li+ electrolyte system, it was found to result in the enhancement of ionic conductivity. The maximum ionic conductivity has been set up to be 1.14 × 10-4 Scm-1 at the optimized concentration of 4 wt% Fe nanofiller-embedded PEO + PVP/Li+ polymer electrolyte nanocomposite at an ambient temperature. PEO + PVP/Li+ + Fe nanofiller (4 wt%) cell exhibited better performance in terms of cell parameters. Based on the cell parameters, the 4 wt% Fe nanofiller-dispersed PEO + PVP/Li+ polymer electrolyte system could be suggested as a perspective candidate for solid-state battery applications.

  12. Ab-initio studies on Li doping, Li-pairs, and complexes between Li and intrinsic defects in ZnO

    NASA Astrophysics Data System (ADS)

    Vidya, R.; Ravindran, P.; Fjellvâg, H.

    2012-06-01

    First-principles density functional calculations have been performed on Li-doped ZnO using all-electron projector augmented plane wave method. Li was considered at six different interstitial sites (Lii), including anti-bonding and bond-center sites and also in substitutional sites such as at Zn-site (Lizn) and at oxygen site (Lio) in the ZnO matrix. Stability of LiZn over Lii is shown to depend on synthetic condition, viz., LiZn is found to be more stable than Lii under O-rich conditions. Hybrid density functional calculations performed on LiZn indicate that it is a deep acceptor with (0/-) transition taking place at 0.74 eV above valence band maximum. The local vibrational frequencies for Li-dopants are calculated and compared with reported values. In addition, we considered the formation of Li-pair complexes and their role on electronic properties of ZnO. Present study suggests that at extreme oxygen-rich synthesis condition, a pair of acceptor type LiZn-complex is found to be stable over the compensating Lii + LiZn pair. The stability of complexes formed between Li impurities and various intrinsic defects is also investigated and their role on electronic properties of ZnO has been analyzed. We have shown that a complex between LiZn and oxygen vacancy has less formation energy and donor-type character and could compensate the holes generated by Li-doping in ZnO.

  13. New design of electric double layer capacitors with aqueous LiOH electrolyte as alternative to capacitor with KOH solution

    NASA Astrophysics Data System (ADS)

    Stepniak, Izabela; Ciszewski, Aleksander

    Activated carbon (AC) fiber cloths and a hydrophobic microporous polypropylene (PP) membrane, both modified with lithiated acetone oligomers, were used as electrodes and a separator in electric double layer capacitors (EDLCs) with aqueous lithium hydroxide (LiOH) as the electrolyte. Electrochemical characteristics of EDLCs were investigated by cyclic voltammetry (CV), galvanostatic charge-discharge cycle tests and impedance spectroscopy (EIS), compared with a case of the capacitor with aqueous potassium hydroxide (KOH) as an electrolyte. As a result, the capacitor with LiOH aqueous solution and a modified separator and electrodes was found to exhibit higher specific capacitance, maximum energy stored and maximum power than that with KOH aqueous solution.

  14. Enhancement of Li+ ion conductivity in solid polymer electrolytes using surface tailored porous silica nanofillers

    NASA Astrophysics Data System (ADS)

    Mohanta, Jagdeep; Singh, Udai P.; Panda, Subhendu K.; Si, Satyabrata

    2016-09-01

    The current study represents the design and synthesis of polyethylene oxide (PEO)-based solid polymer electrolytes by solvent casting approach using surface tailored porous silica as nanofillers. The surface tailoring of porous silica nanostructure is achieved through silanization chemistry using 3-glycidyloxypropyl trimethoxysilane in which silane part get anchored to the silica surface whereas epoxy group get stellated from the silica surface. Surface tailoring of silica with epoxy group increases the room temperature electrochemical performances of the resulting polymer electrolytes. Ammonical hydrolysis of organosilicate precursor is used for both silica preparation and their surface tailoring. The composite solid polymer electrolyte films are prepared by solution mixing of PEO with lithium salt in presence of silica nanofillers and cast into film by solvent drying, which are then characterized by impedance measurement for conductivity study and wide angle x-ray diffraction for change in polymer crystallinity. Room temperature impedance measurement reveals Li+ ion conductivity in the order of 10-4 S cm-1, which is correlated to the decrease in PEO crystallinity. The enhancement of conductivity is further observed to be dependent on the amount of silica as well as on their surface characteristics.

  15. In situ Raman and electrochemical characterization of the role of electrolyte additives in Li/SOCl2 batteries

    NASA Astrophysics Data System (ADS)

    Kovac, M.; Milicev, S.; Kovac, A.; Pejovnik, S.

    1995-05-01

    A simple glass cell has been constructed for in situ Raman characterization of discharge products in Li/SOCl2 batteries with polyvinyl chloride (PVC) and LiAl(SO3Cl4) additives. The assembly enables the characterization of catholyte-soluble discharge products in the electrolyte as well as products on the lithium and carbon electrode surfaces. The effect of the additives was also examined by scanning electron microscopy/energy dispersive spectroscopy and impedance spectroscopy and correlated to the voltage delay in batteries. The best results, as regards to the elimination of the delay effect, were obtained with a new electrolyte consisting of LiAlCl4/SOCl2 with an admixture of PVC and LiAl(SO3Cl4).

  16. Li2S encapsulated by nitrogen-doped carbon for lithium sulfur batteries

    DOE PAGES

    Chen, Lin; Liu, Yuzi; Ashuri, Maziar; ...

    2014-09-26

    Using high-energy ball milling of the Li2S plus carbon black mixture followed by carbonization of pyrrole, we have established a facile approach to synthesize Li2S-plus-C composite particles of average size 400 nm, encapsulated by a nitrogen-doped carbon shell. Such an engineered core–shell structure exhibits an ultrahigh initial discharge specific capacity (1029 mAh/g), reaching 88% of the theoretical capacity (1,166 mAh/g of Li2S) and thus offering the highest utilization of Li2S in the cathode among all of the reported works for the encapsulated Li2S cathodes. This Li2S/C composite core with a nitrogen-doped carbon shell can still retain 652 mAh/g after prolongedmore » 100 cycles. These superior properties are attributed to the nitrogen-doped carbon shell that can improve the conductivity to enhance the utilization of Li2S in the cathode. As a result, fine particle sizes and the presence of carbon black within the Li2S core may also play a role in high utilization of Li2S in the cathode.« less

  17. Improved electrolyte and its application in LiNi1/3Mn1/3Co1/3O2-Graphite full cells

    NASA Astrophysics Data System (ADS)

    Liu, Minghong; Dai, Fang; Ma, Zhiru; Ruthkosky, Marty; Yang, Li

    2014-12-01

    Lithium oxalatodifluoroborate (LiODFB) has been synthesized and used as a novel electrolyte additive. Standard and modified electrolytes were flame-sealed in NMR tubes and stored at 60 °C for 3 months. Multiple nuclear NMR (1H, 11B, 13C, 19F, 31P) studies confirmed that the modified electrolyte (2% LiODFB added) showed no signs of decomposition as that of regular electrolyte, which is possibly due to the -F of LiPF6 and oxalate of LiODFB ligand exchange effect. The high temperature stabilization mechanism of the added LiODFB was studied using quantum mechanical calculations. Electrochemical tests of LiNi1/3Mn1/3Co1/3O2 (NMC)-Graphite full-cells with and without LiODFB as the electrolyte additive were conducted. When cycling with the NMC-Graphite full-cell at elevated temperature (60 °C), the 100th cycle capacity retention rate of the modified electrolyte was 60%, compared to 27% with the standard electrolyte. The EIS study indicates the full-cells with LiODFB have much lower interfacial impedance than the standard cells. Theoretical calculations reveal that LiODFB generates a layer of thin and resilient SEI on the graphite surface at a higher reduction potential than ethylene carbonate (EC) due to its higher ring strain and protects graphite from the toxic Mn2+ resulting in improved electrochemical performance of NMC-Graphite based cells.

  18. Excellent stability of a lithium-ion-conducting solid electrolyte upon reversible Li+/H+ exchange in aqueous solutions

    DOE PAGES

    Ma, Cheng; Rangasamy, Ezhiylmurugan; Liang, Chengdu; ...

    2014-10-21

    Batteries with an aqueous catholyte and a Li metal anode have attracted interest owing to their exceptional energy density and high charge/discharge rate. The long-term operation of such batteries requires that the solid electrolyte separator between the anode and aqueous solutions must be compatible with Li and stable over a wide pH range. Unfortunately, no such compound has yet been reported. In this study, an excellent stability in neutral and strongly basic solutions was observed when using the cubic Li7La3Zr2O12 garnet as a Li-stable solid electrolyte. The material underwent a Li+/H+ exchange in aqueous solutions. Nevertheless, its structure remained unchangedmore » even under a high exchange rate of 63.6%. When treated with a 2 M LiOH solution, the Li+/H+ exchange was reversed without any structural change. Furthermore, these observations suggest that cubic Li7La3Zr2O12 is a promising candidate for the separator in aqueous lithium batteries.« less

  19. 3d-Metal Doped into LiMn2O4 Thin Films

    SciTech Connect

    Bates, J.B.; Ueda, A.; Zuhr, R.A.

    1998-11-01

    3d-metal (Me) doped LiMn{sub 2}O{sub 4} thin films were deposited by rf magnetron sputtering of Li[Mn{sub 1.9}Me{sub 0.1}]O{sub 4} targets in Ar + N{sub 2} and Ar + O{sub 2} gas mixtures and annealed at 750{degrees}C in O{sub 2} for 1 h. From XRD measurements, the structure of the Me-doped thin film was dependent upon the element and the deposition conditions. The doping level of Me/Mn of cubic phase was less than 0.1 by EDX measurements. The Ti-LiMn{sub 2}O{sub 4} films exhibited a capacity close to theoretical for stoichiometric LiMn{sub 2}O{sub 4}. This improvement at 4 V comes at the expense of the capacity at 5 V. Cells with Ti-doped films exhibited the same low capacity fade as those with undoped LiMn{sub 2}O{sub 4} cathodes. Similar electrochemical changes were observed with the Cr- and Zn-LiMn{sub 2}O{sub 4} films. The discharge capacities above 4.5 V for the Ni-doped films were about equal to those below 4.5 V, and the thin-film cells could be cycled reversibility between 3.5 and 5.3 V.

  20. Studies on various properties of pure and Li-doped Barium Hydrogen Phosphate (BHP) single crystals

    NASA Astrophysics Data System (ADS)

    Nallamuthu, D.; Selvarajan, P.; Freeda, T. H.

    2010-12-01

    Single crystals of pure and Li-doped barium hydrogen phosphate (BHP) were grown by solution method with gel technique. Various properties of the harvested crystals were studied by carrying out single crystal and powder XRD, FTIR, TG/DTA, microhardness and dielectric studies. Atomic absorption study was carried out for Li-doped BHP crystal to check the presence of Li dopants. Unit cell dimensions and diffracting planes of the grown crystals have been identified from XRD studies. Functional groups of the title compounds have been identified from FTIR studies. Density of the grown crystals was calculated using the XRD data. Thermal stability of the samples was checked by TG/DTA studies. Mechanical and dielectric characterizations of the harvested pure and Li-doped BHP crystals reveal the mechanical strength and ferroelectric transition. The observed results are reported and discussed.

  1. Atomic-Scale Mechanisms for Electrolyte Decomposition in Li-ion Battery Cathodes

    NASA Astrophysics Data System (ADS)

    Fuhst, Mallory; Siegel, Donald

    Li-ion batteries using high energy density LiCoO2 (LCO) intercalation cathodes are known to generate gaseous species inside the cell, which can lead to venting flammable solvent vapor. It has been hypothesized that reactions at the cathode/electrolyte interface catalyze the production of these gaseous species. To elucidate the underlying reaction mechanism, first principles calculations were used to model interactions between LCO surfaces and Ethylene Carbonate (EC), a commonly used solvent in Li-ion batteries. A Metropolis Monte Carlo algorithm was used to identify likely low energy adsorption configurations for EC on the (10-14) surface of LCO. Several of these geometries were further analyzed with DFT. The thermodynamics and kinetics of EC decomposition were evaluated for plausible reaction pathways and associated various solvent decomposition mechanisms, such as hydrogen abstraction. Preliminary results indicate that hydrogen abstraction may lead to the spontaneous decomposition of EC into CO and other adsorbed species at the surface. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE 1256260.

  2. Promising Cell Configuration for Next-Generation Energy Storage: Li2S/Graphite Battery Enabled by a Solvate Ionic Liquid Electrolyte.

    PubMed

    Li, Zhe; Zhang, Shiguo; Terada, Shoshi; Ma, Xiaofeng; Ikeda, Kohei; Kamei, Yutaro; Zhang, Ce; Dokko, Kaoru; Watanabe, Masayoshi

    2016-06-29

    Lithium-ion sulfur batteries with a [graphite|solvate ionic liquid electrolyte|lithium sulfide (Li2S)] structure are developed to realize high performance batteries without the issue of lithium anode. Li2S has recently emerged as a promising cathode material, due to its high theoretical specific capacity of 1166 mAh/g and its great potential in the development of lithium-ion sulfur batteries with a lithium-free anode such as graphite. Unfortunately, the electrochemical Li(+) intercalation/deintercalation in graphite is highly electrolyte-selective: whereas the process works well in the carbonate electrolytes inherited from Li-ion batteries, it cannot take place in the ether electrolytes commonly used for Li-S batteries, because the cointercalation of the solvent destroys the crystalline structure of graphite. Thus, only very few studies have focused on graphite-based Li-S full cells. In this work, simple graphite-based Li-S full cells were fabricated employing electrolytes beyond the conventional carbonates, in combination with highly loaded Li2S/graphene composite cathodes (Li2S loading: 2.2 mg/cm(2)). In particular, solvate ionic liquids can act as a single-phase electrolyte simultaneously compatible with both the Li2S cathode and the graphite anode and can further improve the battery performance by suppressing the shuttle effect. Consequently, these lithium-ion sulfur batteries show a stable and reversible charge-discharge behavior, along with a very high Coulombic efficiency.

  3. Demonstrating the potential of yttrium-doped barium zirconate electrolyte for high-performance fuel cells.

    PubMed

    Bae, Kiho; Jang, Dong Young; Choi, Hyung Jong; Kim, Donghwan; Hong, Jongsup; Kim, Byung-Kook; Lee, Jong-Ho; Son, Ji-Won; Shim, Joon Hyung

    2017-02-23

    In reducing the high operating temperatures (≥800 °C) of solid-oxide fuel cells, use of protonic ceramics as an alternative electrolyte material is attractive due to their high conductivity and low activation energy in a low-temperature regime (≤600 °C). Among many protonic ceramics, yttrium-doped barium zirconate has attracted attention due to its excellent chemical stability, which is the main issue in protonic-ceramic fuel cells. However, poor sinterability of yttrium-doped barium zirconate discourages its fabrication as a thin-film electrolyte and integration on porous anode supports, both of which are essential to achieve high performance. Here we fabricate a protonic-ceramic fuel cell using a thin-film-deposited yttrium-doped barium zirconate electrolyte with no impeding grain boundaries owing to the columnar structure tightly integrated with nanogranular cathode and nanoporous anode supports, which to the best of our knowledge exhibits a record high-power output of up to an order of magnitude higher than those of other reported barium zirconate-based fuel cells.

  4. Demonstrating the potential of yttrium-doped barium zirconate electrolyte for high-performance fuel cells

    PubMed Central

    Bae, Kiho; Jang, Dong Young; Choi, Hyung Jong; Kim, Donghwan; Hong, Jongsup; Kim, Byung-Kook; Lee, Jong-Ho; Son, Ji-Won; Shim, Joon Hyung

    2017-01-01

    In reducing the high operating temperatures (≥800 °C) of solid-oxide fuel cells, use of protonic ceramics as an alternative electrolyte material is attractive due to their high conductivity and low activation energy in a low-temperature regime (≤600 °C). Among many protonic ceramics, yttrium-doped barium zirconate has attracted attention due to its excellent chemical stability, which is the main issue in protonic-ceramic fuel cells. However, poor sinterability of yttrium-doped barium zirconate discourages its fabrication as a thin-film electrolyte and integration on porous anode supports, both of which are essential to achieve high performance. Here we fabricate a protonic-ceramic fuel cell using a thin-film-deposited yttrium-doped barium zirconate electrolyte with no impeding grain boundaries owing to the columnar structure tightly integrated with nanogranular cathode and nanoporous anode supports, which to the best of our knowledge exhibits a record high-power output of up to an order of magnitude higher than those of other reported barium zirconate-based fuel cells. PMID:28230080

  5. Demonstrating the potential of yttrium-doped barium zirconate electrolyte for high-performance fuel cells

    NASA Astrophysics Data System (ADS)

    Bae, Kiho; Jang, Dong Young; Choi, Hyung Jong; Kim, Donghwan; Hong, Jongsup; Kim, Byung-Kook; Lee, Jong-Ho; Son, Ji-Won; Shim, Joon Hyung

    2017-02-01

    In reducing the high operating temperatures (>=800 °C) of solid-oxide fuel cells, use of protonic ceramics as an alternative electrolyte material is attractive due to their high conductivity and low activation energy in a low-temperature regime (<=600 °C). Among many protonic ceramics, yttrium-doped barium zirconate has attracted attention due to its excellent chemical stability, which is the main issue in protonic-ceramic fuel cells. However, poor sinterability of yttrium-doped barium zirconate discourages its fabrication as a thin-film electrolyte and integration on porous anode supports, both of which are essential to achieve high performance. Here we fabricate a protonic-ceramic fuel cell using a thin-film-deposited yttrium-doped barium zirconate electrolyte with no impeding grain boundaries owing to the columnar structure tightly integrated with nanogranular cathode and nanoporous anode supports, which to the best of our knowledge exhibits a record high-power output of up to an order of magnitude higher than those of other reported barium zirconate-based fuel cells.

  6. A Study on Electrolytic Corrosion of Boron-Doped Diamond Electrodes when Decomposing Organic Compounds.

    PubMed

    Kashiwada, Takeshi; Watanabe, Takeshi; Ootani, Yusuke; Tateyama, Yoshitaka; Einaga, Yasuaki

    2016-03-02

    Electrolytic corrosion of boron-doped diamond (BDD) electrodes after applying a high positive potential to decompose organic compounds in aqueous solution was studied. Scanning electron microscopy images, Raman spectra, and glow discharge optical emission spectroscopy revealed that relatively highly boron-doped domains were primarily corroded and relatively low boron-doped domains remained after electrolysis. The corrosion due to electrolysis was observed especially in aqueous solutions of acetic acid or propionic acid, while it was not observed in other organic compounds such as formic acid, glucose, and methanol. Electron spin resonance measurements after electrolysis in the acetic acid solution revealed the generation of methyl radicals on the BDD electrodes. Here, the possible mechanisms for the corrosion are discussed. Dangling bonds may be formed due to abstraction of OH groups from C-OH functional groups by methyl radicals generated on the surface of the BDD electrodes. As a result, the sp(3) diamond structure would be converted to the sp(2) carbon structure, which can be easily etched. Furthermore, to prevent electrolytic corrosion during electrolysis, both the current density and the pH condition in the aqueous solution were optimized. At low current densities or high pH, the BDD electrodes were stable without electrolytic corrosion even in the acetic acid aqueous solution.

  7. Energetics of a Li Atom adsorbed on B/N doped graphene with monovacancy

    SciTech Connect

    Rani, Babita; Jindal, V.K.; Dharamvir, Keya

    2016-08-15

    We use density functional theory (DFT) to study the adsorption properties and diffusion of Li atom across B/N-pyridinic graphene. Regardless of the dopant type, B atoms of B-pyridinic graphene lose electron density. On the other hand, N atoms (p-type dopants) have tendency to gain electron density in N-pyridinic graphene. Higher chemical reactivity and electronic conductivity of B/N-pyridinic graphene are responsible for stronger binding of Li with the substrates as compared to pristine graphene. The binding energy of Li with B/N-pyridinic graphene exceeds the cohesive energy of bulk Li, making it energetically unfavourable for Li to form clusters on these substrates. Li atom gets better adsorbed on N-pyridinic graphene due to an additional p-p hybridization of the orbitals while Li on B-pyridinic prefers the ionic bonding. Also, significant distortion of N-pyridinic graphene upon Li adsorption is a consequence of the change in bonding mechanism between Li atom and the substrate. Our results show that bonding character and hence binding energies between Li and graphene can be tuned with the help of B/N doping of monovacancy defects. Further, the sites for most stable adsorption are different for the two types of doped and defective graphene, leading to greater Li uptake capacity of B-pyridinic graphene near the defect. In addition, B-pyridinic graphene offering lower diffusion barrier, ensures better Li kinetics. Thus, B-pyridinic graphene presents itself as a better anode material for LIBs as compared to N-pyridinic graphene. - Graphical abstract: Adsorption and diffusion of Li atom across the B/N doped monovacancy graphene is studied using ab-initio DFT calculations. Our results show that bonding mechanism and binding of Li with graphene can be tuned with the help of N/B doping of defects. Also, B-pyridinic graphene presents itself as a better anode material for lithium ion batteries as compared to N-pyridinic graphene. Display Omitted - Highlights: • Density

  8. 3D hierarchical assembly of ultrathin MnO2 nanoflakes on silicon nanowires for high performance micro-supercapacitors in Li- doped ionic liquid

    PubMed Central

    Dubal, Deepak P.; Aradilla, David; Bidan, Gérard; Gentile, Pascal; Schubert, Thomas J.S.; Wimberg, Jan; Sadki, Saïd; Gomez-Romero, Pedro

    2015-01-01

    Building of hierarchical core-shell hetero-structures is currently the subject of intensive research in the electrochemical field owing to its potential for making improved electrodes for high-performance micro-supercapacitors. Here we report a novel architecture design of hierarchical MnO2@silicon nanowires (MnO2@SiNWs) hetero-structures directly supported onto silicon wafer coupled with Li-ion doped 1-Methyl-1-propylpyrrolidinium bis(trifluromethylsulfonyl)imide (PMPyrrBTA) ionic liquids as electrolyte for micro-supercapacitors. A unique 3D mesoporous MnO2@SiNWs in Li-ion doped IL electrolyte can be cycled reversibly across a voltage of 2.2 V and exhibits a high areal capacitance of 13 mFcm−2. The high conductivity of the SiNWs arrays combined with the large surface area of ultrathin MnO2 nanoflakes are responsible for the remarkable performance of these MnO2@SiNWs hetero-structures which exhibit high energy density and excellent cycling stability. This combination of hybrid electrode and hybrid electrolyte opens up a novel avenue to design electrode materials for high-performance micro-supercapacitors. PMID:25985388

  9. Nitrile functionalized disiloxanes with dissolved LiTFSI as lithium ion electrolytes with high thermal and electrochemical stability

    NASA Astrophysics Data System (ADS)

    Pohl, Benjamin; Hiller, Martin M.; Seidel, Sarah M.; Grünebaum, Mariano; Wiemhöfer, Hans-Dieter

    2015-01-01

    Liquid disiloxanes functionalized with terminal nitrile groups are introduced as alternative non-volatile solvents for lithium-ion battery electrolytes in combination with LiTFSI as lithium salt. Two series of disiloxanes were investigated differing with respect to the attachment of the nitrile containing side group to silicon, i.e. via a Si-C or a Si-O bond. Total conductivities up to 1 mS cm-1 at 30 °C were measured by impedance spectroscopy. Electrochemical characterization was done on half cells using LiFePO4 cathodes by cyclic voltammetry and constant current cycling. Attractive issues and advantages of the investigated LiTFSI containing disiloxanes in comparison to current electrolyte solvents are: a) In spite of the presence of LiTFSI, the aluminum pitting corrosion is suppressed, b) the electrochemical stability window is extended on the cathode side up to 5.6 V vs. Li/Li+, for a LiTFSI concentration of 0.7 mol kg-1, c) the reported nitrile functionalized disiloxanes show excellent thermal stability with a boiling point up to 106 °C (0.1 mbar), a rather low glass transition temperature of -107 °C, while no melting/crystallization was observed.

  10. Temperature Dependence of Aliovalent-vanadium Doping in LiFePO4 Cathodes

    SciTech Connect

    Harrison, Katharine L; Bridges, Craig A; Paranthaman, Mariappan Parans; Idrobo Tapia, Juan C; Manthiram, Arumugam; Goodenough, J. B.; Segre, C; Katsoudas, John; Maroni, V. A.

    2013-01-01

    Vanadium-doped olivine LiFePO4 cathode materials have been synthesized by a novel low-temperature microwave-assisted solvothermal (MW-ST) method at 300 oC. Based on chemical and powder neutron/X-ray diffraction analysis, the compositions of the synthesized materials were found to be LiFe1-3x/2Vx x/2PO4 (0 x 0.2) with the presence of a small number of lithium vacancies charge-compensated by V4+, not Fe3+, leading to an average oxidation state of ~ 3.2+ for vanadium. Heating the pristine 15 % V-doped sample in inert or reducing atmospheres led to a loss of vanadium from the olivine lattice with the concomitant formation of a Li3V2(PO4)3 impurity phase; after phase segregation, a partially V-doped olivine phase remained. For comparison, V-doped samples were also synthesized by conventional ball milling and heating, but only ~ 10 % V could be accommodated in the olivine lattice in agreement with previous studies. The higher degree of doping realized with the MW-ST samples demonstrates the temperature dependence of the aliovalent-vanadium doping in LiFePO4.

  11. Quadratic nonlinear optical parameters of 7% MgO-doped LiNbO3 crystal

    NASA Astrophysics Data System (ADS)

    Kulyk, B.; Kapustianyk, V.; Figà, V.; Sahraoui, B.

    2016-06-01

    Pure and 7% MgO-doped lithium niobate (LiNbO3) single crystals were grown by the Czochralski technique. The shift of optical absorption edge in 7% MgO-doped crystal in direction of shorter wavelength compared to undoped crystal was observed. The second harmonic generation measurements of 7% MgO-doped LiNbO3 crystal were performed at room temperature by means of the rotational Maker fringe technique using Nd:YAG laser generating at 1064 nm in picoseconds regime. Experimentally obtained value of nonlinear optical coefficient d33 for 7% MgO-doped LiNbO3 was found to be less than for undoped crystal but higher than for 5% MgO-doped. I-type phase-matched second harmonic generation was achieved and the value of phase-matched angle was calculated. High quadratic nonlinearity together with tolerance to intensive laser irradiation makes 7% MgO-doped LiNbO3 crystal interesting for application in optoelectronics.

  12. Functionalized ionic liquids based on quaternary ammonium cations with two ether groups as new electrolytes for Li/LiFePO4 secondary battery

    NASA Astrophysics Data System (ADS)

    Jin, Yide; Zhang, Jianhao; Song, Jianzhi; Zhang, Zhengxi; Fang, Shaohua; Yang, Li; Hirano, Shin-ichi

    2014-05-01

    New functionalized ILs based on quaternary ammonium cations with two ether groups and bis(trifluoromethanesulfonyl)imide (TFSA-) anion are synthesized and characterized. Physical and electrochemical properties, including melting point, thermal stability, viscosity, conductivity and electrochemical stability are investigated for these ILs. All these ILs are liquids at room temperature except N,N-diethyl-N,N-bis(2-ethoxyethyl)ammonium TFSA (N22(2o2)(2o2)-TFSA, Tm = 29.7 °C), and the viscosities of N-methyl-N-ethyl-N-(2-methoxyethyl)-N-(2-ethoxyethyl)ammonium TFSA (N12(2o1)(2o2)-TFSA) and N-methyl-N-ethyl-N,N-bis(2-ethoxyethyl)ammonium TFSA (N12(2o2)(2o2)-TFSA) are 68.0 cP and 63.0 cP at 25 °C, respectively. N-Methyl-N,N-diethyl-N-(2-methoxyethyl)ammonium TFSA (DEME-TFSA) and five ILs with lower viscosity are chosen to dissolve 0.6 mol kg-1 of LiTFSA as IL electrolytes without additive for lithium battery. Lithium plating and striping on Ni electrode can be observed in these IL electrolytes, and cycle performances of lithium symmetrical cells are also investigated for these IL electrolytes. Li/LiFePO4 cells using these IL electrolytes without additives have good cycle property at the current rate of 0.1 C, and the N-methyl-N-ethyl-N,N-bis(2-methoxyethyl)ammonium TFSA (N12(2o1)(2o1)-TFSA) and N12(2o2)(2o2)-TFSA electrolytes own better rate property than DEME-TFSA electrolyte.

  13. Niobium-doped titanium oxide anode and ionic liquid electrolyte for a safe sodium-ion battery

    NASA Astrophysics Data System (ADS)

    Usui, Hiroyuki; Domi, Yasuhiro; Shimizu, Masahiro; Imoto, Akinobu; Yamaguchi, Kazuki; Sakaguchi, Hiroki

    2016-10-01

    The anode properties of Nb-doped rutile TiO2 electrodes were investigated in an ionic liquid electrolyte comprised of N-methyl-N-propylpyrrolidinium cation and bis(fluorosulfonyl)amide anion for use in a safe Na-ion battery. Although the electrolyte's conductivity was lower than that of a conventional organic electrolyte at 30 °C, it showed high conductivity comparable to that of the organic electrolyte at 60 °C. The Nb-doped TiO2 electrode showed excellent cyclability in the ionic liquid electrolyte at 60 °C: a high capacity retention of 97% was observed even at the 350th cycle, which is comparable to value in the organic electrolyte (91%). In a non-flammability test in a closed system, no ignition was observed with the ionic liquid electrolyte even at 300 °C. These results indicate that combination of a Nb-doped TiO2 anode and ionic liquid electrolyte gives not only an excellent cyclability but also high safety for a Na-ion battery operating at a temperature below the sodium's melting point of 98 °C.

  14. Nanoscale imaging of fundamental Li battery chemistry: solid-electrolyte interphase formation and preferential growth of lithium metal nanoclusters

    DOE PAGES

    Sacci, Robert L; Black, Jennifer M.; Wisinger, Nina; ...

    2015-02-23

    The performance characteristics of Li-ion batteries are intrinsically linked to evolving nanoscale interfacial electrochemical reactions. To probe the mechanisms of solid electrolyte interphase formation and Li electrodeposition from a standard battery electrolyte, we use in situ electrochemical scanning transmission electron microscopy for controlled potential sweep-hold electrochemical measurements with simultaneous BF and ADF STEM image acquisition. Through a combined quantitative electrochemical measurement and quantitative STEM imaging approach, based upon electron scattering theory, we show that chemically sensitive ADF STEM imaging can be used to estimate the density of evolving SEI constituents and distinguish contrast mechanisms of Li-bearing components in the liquidmore » cell.« less

  15. A hybrid Li-air battery with buckypaper air cathode and sulfuric acid electrolyte

    SciTech Connect

    Li, YF; Huang, K; Xing, YC

    2012-10-30

    We demonstrate a type of carbon nanotube based buckypaper cathode in a hybrid electrolyte Li-air battery (HyLAB) that showed outstanding discharging performances. The HyLAB has sulfuric acid as the catholyte and a large active electrode area (10 cm(2)). The active cathode layer was made from a buckypaper with 5 wt.% Pt supported on carbon nanotubes (Pt/CNTs) for oxygen reduction and evolution. A similar cathode was constructed with a catalyst of 5 wt.% Pt supported on carbon black (Pt/CB). It is demonstrated that sulfuric acid can achieve high discharging current densities while maintaining relatively high cell potentials. The cell with Pt/CNTs showed a much better performance than with Pt/CB at high current densities. The HyLAB with Pt/CNTs achieved a discharging capacity of 306 mAh/g and a cell voltage of 3.15 V at 0.2 mA/cm(2). The corresponding specific energy is 1067 Wh/kg based on the total weight of the sulfuric acid. Slow decrease in performance was observed, but it can be recovered by refilling the cell with new electrolyte after continuous discharging of more than 75 h. A charge-discharge experiment at 0.2 mA/cm(2) showed that the cell was rechargeable with a capacity of more than 300 mAh/g. (c) 2012 Elsevier Ltd. All rights reserved.

  16. An upper limit of Cr-doping level to Retain Zero-strain Characteristics of Li4Ti5O12 Anode Material for Li-ion Batteries

    PubMed Central

    Song, Hannah; Jeong, Tae-Gyung; Yun, Su-Won; Lee, Eun-Kyung; Park, Shin-Ae; Kim, Yong-Tae

    2017-01-01

    Since Li4Ti5O12 as a promising anode material in lithium-ion batteries (LIBs) has a poor rate performance due to low electronic conductivity, a doping of Li4Ti5O12 with heterogeneous atoms has been considered to overcome this problem. Herein, we report that there is an upper limit of doping level to maintain the zero strain characteristics of Li4Ti5O12 lattice during charge/discharge process. By using synchrotron studies, it was revealed that the Li+ diffusivity was maximized at a certain doping level for which the conductivity was markedly increased with maintaining the zero strain characteristics. However, with more doses of dopants over the upper limit, the lattice shrank and therefore the Li+ diffusivity decreased, although the electronic conductivity was further increased in comparison with the optimal doping level. PMID:28233818

  17. An upper limit of Cr-doping level to Retain Zero-strain Characteristics of Li4Ti5O12 Anode Material for Li-ion Batteries

    NASA Astrophysics Data System (ADS)

    Song, Hannah; Jeong, Tae-Gyung; Yun, Su-Won; Lee, Eun-Kyung; Park, Shin-Ae; Kim, Yong-Tae

    2017-02-01

    Since Li4Ti5O12 as a promising anode material in lithium-ion batteries (LIBs) has a poor rate performance due to low electronic conductivity, a doping of Li4Ti5O12 with heterogeneous atoms has been considered to overcome this problem. Herein, we report that there is an upper limit of doping level to maintain the zero strain characteristics of Li4Ti5O12 lattice during charge/discharge process. By using synchrotron studies, it was revealed that the Li+ diffusivity was maximized at a certain doping level for which the conductivity was markedly increased with maintaining the zero strain characteristics. However, with more doses of dopants over the upper limit, the lattice shrank and therefore the Li+ diffusivity decreased, although the electronic conductivity was further increased in comparison with the optimal doping level.

  18. Characterization of conducting cellulose acetate based polymer electrolytes doped with "green" ionic mixture.

    PubMed

    Ramesh, S; Shanti, R; Morris, Ezra

    2013-01-02

    Polymer electrolytes were developed by solution casting technique utilizing the materials of cellulose acetate (CA), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and deep eutectic solvent (DES). The DES is synthesized from the mixture of choline chloride and urea of 1:2 ratios. The increasing DES content well plasticizes the CA:LiTFSI:DES matrix and gradually improves the ionic conductivity and chemical integrity. The highest conducting sample was identified for the composition of CA:LiTFSI:DES (28 wt.%:12 wt.%:60 wt.%), which has the greatest ability to retain the room temperature ionic conductivity over the entire 30 days of storage time. The changes in FTIR cage peaks upon varying the DES content in CA:LiTFSI:DES prove the complexation. This complexation results in the collapse of CA matrix crystallinity, observed from the reduced intensity of XRD diffraction peaks. The DES-plasticized sample is found to be more heat-stable compared to pure CA. Nevertheless, the addition of DES diminishes the CA:LiTFSI matrix's heat-resistivity but at the minimum addition the thermal stability is enhanced.

  19. Rigid-flexible coupling high ionic conductivity polymer electrolyte for an enhanced performance of LiMn2O4/graphite battery at elevated temperature.

    PubMed

    Hu, Pu; Duan, Yulong; Hu, Deping; Qin, Bingsheng; Zhang, Jianjun; Wang, Qingfu; Liu, Zhihong; Cui, Guanglei; Chen, Liquan

    2015-03-04

    LiMn2O4-based batteries exhibit severe capacity fading during cycling or storage in LiPF6-based liquid electrolytes, especially at elevated temperatures. Herein, a novel rigid-flexible gel polymer electrolyte is introduced to enhance the cyclability of LiMn2O4/graphite battery at elevated temperature. The polymer electrolyte consists of a robust natural cellulose skeletal incorporated with soft segment poly(ethyl α-cyanoacrylate). The introduction of the cellulose effectively overcomes the drawback of poor mechanical integrity of the gel polymer electrolyte. Density functional theory (DFT) calculation demonstrates that the poly(ethyl α-cyanoacrylate) matrices effectively dissociate the lithium salt to facilitate ionic transport and thus has a higher ionic conductivity at room temperature. Ionic conductivity of the gel polymer electrolyte is 3.3 × 10(-3) S cm(-1) at room temperature. The gel polymer electrolyte remarkably improves the cycling performance of LiMn2O4-based batteries, especially at elevated temperatures. The capacity retention after the 100th cycle is 82% at 55 °C, which is much higher than that of liquid electrolyte (1 M LiPF6 in carbonate solvents). The polymer electrolyte can significantly suppress the dissolution of Mn(2+) from surface of LiMn2O4 because of strong interaction energy of Mn(2+) with PECA, which was investigated by DFT calculation.

  20. A review on the separators of liquid electrolyte Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Sheng Shui

    This paper reviews the separators used in liquid electrolyte Li-ion batteries. According to the structure and composition of the membranes, the battery separators can be broadly divided as three groups: (1) microporous polymer membranes, (2) non-woven fabric mats and (3) inorganic composite membranes. The microporous polymer membranes are characterised by their thinness and thermal shutdown properties. The non-woven mats have high porosity and a low cost, while the composite membranes have excellent wettability and exceptional thermal stability. The manufacture, characteristics, performance and modifications of these separators are introduced and discussed. Among numerous battery separators, the thermal shutdown and ceramic separators are of special importance in enhancing the safety of Li-ion batteries. The former consists of either a polyethylene (PE)-polypropylene (PP) multilayer structure or a PE-PP blend which increases safety by allowing meltdown of the PE to close the ionic conduction pathways at a temperature below that at which thermal runway occurs. Whereas the latter comprises nano-size ceramic materials coated on two sides of a flexible and highly porous non-woven matrix which enhances the safety by retaining extremely stable dimensions even at very high temperatures to prevent the direct contact of the electrodes.

  1. Lithium-ion-conducting solid electrolytes in the Li/sub 4/GeO/sub 4/-Li/sub 2/SeO/sub 4/ system

    SciTech Connect

    Burmakin, E.I.; Alikin, V.N.; Stepanov, G.K.

    1986-02-01

    The authors studied the Li/sub 4/GeO/sub 4/-Li/sub 2/SeO/sub 4/ system as a continuation of an earlier investigation of solid electrolytes on the basis of lithium orthogermanate. The solid electrolytes were synthesized by sintering samples which had been pressed from a mixture of highly disperse powders of Li/sub 2/SeO/sub 4/ and Li/sub 4/GeO/sub 4/. The x-ray phase analysis was performed with a DRON-2 diffractometer in Cu Kalpha-radiation with a nickel filter. Electric resistance was measured with an R502 ac bridge using silver electrodes that had been applied thermochemically with a paste based on silver carbonate. The lowest values of specific resistance are seen near the lower limit of the single-phase region of P-solid solutions. This is in accord with the decisive influence of the concentration of highly mobile carriers (the interstitial lithium ions) on the transport properties of structures similar to gamma-Li/sub 3/PO/sub 4/. The number of interstitial lithium ions increases with decreasing x, and will be highest at the lower limit of the region of existence of P-solid solutions.

  2. Natural abundance 17O, 6Li NMR and molecular modeling studies of the solvation structures of lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane liquid electrolytes

    SciTech Connect

    Wan, Chuan; Hu, Mary Y.; Borodin, Oleg; Qian, Jiangfeng; Qin, Zhaohai; Zhang, Ji-Guang; Hu, Jian Zhi

    2016-03-01

    Natural abundance 17O and 6Li NMR experiments, quantum chemistry and molecular dynamics studies were employed to investigate the solvation structures of Li+ at various concentrations of LiFSI in DME electrolytes in an effort to solve this puzzle. It was found that the chemical shifts of both 17O and 6Li changed with the concentration of LiFSI, indicating the changes of solvation structures with concentration. For the quantum chemistry calculations, the coordinated cluster LiFSI(DME)2 forms at first, and its relative ratio increases with increasing LiFSI concentration to 1 M. Then the solvation structure LiFSI(DME) become the dominant component. As a result, the coordination of forming contact ion pairs between Li+ and FSI- ion increases, but the association between Li+ and DME molecule decreases. Furthermore, at LiFSI concentration of 4 M the solvation structures associated with Li+(FSI-)2(DME), Li+2(FSI-)(DME)4 and (LiFSI)2(DME)3 become the dominant components. For the molecular dynamics simulation, with increasing concentration, the association between DME and Li+ decreases, and the coordinated number of FSI- increases, which is in perfect accord with the DFT results. These results provide more insight on the fundamental mechanism on the very high CE of Li deposition in these electrolytes, especially at high current density conditions.

  3. Performance of Wide Operating Temperature Range Electrolytes in Quallion Prototype Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Tomcsi, M. R.; Nagata, M.; Visco, V.; Tsukamoto, H.

    2010-01-01

    For a number of applications, there is a continued interest in the development of rechargeable lithium-based batteries that can effectively operate over a wide temperature range (i.e., -40 to +70 deg C). These applications include powering future planetary rovers for NASA, enabling the next generation of automotive batteries for DOE, and supporting many DOD applications. Li-ion technology has been demonstrated to have good performance over a reasonably wide temperature range with many systems; however, there is still a desire to improve the low temperature rate capacity as well as the high temperature resilience. In the current study, we would like to present recent results obtained with prototype Li-Ion cells (manufactured by Quallion, LLC) which include various wide operating temperature range electrolytes developed by both JPL and Quallion. To demonstrate the viability of the technology, a number of performance tests were carried out, including: (a) discharge rate characterization over a wide temperature range (down to -60 deg C) using various rates (up to 20C rates), (b) discharge rate characterization at low temperatures with low temperature charging, (c) variable temperature cycling over a wide temperature range (-40 to +70 deg C), and (d) cycling at high temperature (50 deg C). As will be discussed, impressive rate capability was observed at low temperatures with many systems, as well as good resilience to high temperature cycling. To augment the performance testing on the prototype cells, a number of experimental three electrodes cells were fabricated (including Li reference electrodes) to allow the determination of the lithium kinetics of the respective electrodes and interfacial properties as a function of temperatures.

  4. Microporous Ni-doped TiO2 film photocatalyst by plasma electrolytic oxidation.

    PubMed

    Yao, Zhongping; Jia, Fangzhou; Tian, Shujun; Li, ChunXiang; Jiang, Zhaohua; Bai, Xuefeng

    2010-09-01

    Ni-doped TiO2 film catalysts were prepared by a plasma electrolytic oxidation (PEO) method and were mainly characterized by means of SEM, EDS, XRD, XPS, and DRS, respectively. The effects of Ni doping on the structure, composition and optical absorption property of the film catalysts were investigated along with their inherent relationships. The results show that the film catalyst is composed of anatase and rutile TiO2 with microporous structure. Doping Ni changes the phase composition and the lattice parameters (interplanar crystal spacing and cell volume) of the films. The optical absorption range of TiO2 film gradually expands and shifts to the red with increasing dosages. Both direct and indirect transition band gaps of the TiO2 films are deduced consequently. Moreover, the photocatalytic activity of the film catalysts for splitting Na2S+Na2SO3 solution into H2 is enhanced by doping with an appropriate amount of Ni. The as-prepared TiO2 film catalyst doping with 10 g/L of Ni(Ac)2 presents the highest photocatalytic reducing activity.

  5. Structural and magnetic properties of quasi-one-dimensional doped LiCuVO4

    NASA Astrophysics Data System (ADS)

    Kumar, Abhishek; Kumari, Poonam; Das, A.; Dwivedi, G. D.; Shahi, P.; Shukla, K. K.; Ghosh, A. K.; Nigam, A. K.; Chattopadhyay, K. K.; Chatterjee, Sandip

    2013-12-01

    The Neutron diffraction, X-ray photoemission and Magnetic properties of Zn, Co and Mn-doped LiCuVO4 were investigated. Both with Zn and Co doping the antiferromagnetic correlation increase. On the other hand Mn-doping induces the short range ferromagnetic ordering. Neutron diffraction study does not show any phase transition down to 5 K i.e., there is no indication of long range magnetic ordering. Neutron diffraction study also indicates that with Zn, Co and Mn doping the V-O lengths are changed. Maximum change in the V-O distances is observed for Mn-doped sample. On the other hand, X-ray photoemission spectroscopic data indicates Mn doping converts some Cu2+ ions into Cu3+ ions.

  6. Real-time tracking the Li+-ion transition behavior and dynamics in solid Poly(vinyl alcohol)/LiClO4 electrolytes

    PubMed Central

    Bao, Lixia; Zou, Xin; Luo, Xin; Pu, Yanlei; Wang, Jiliang; Lei, Jingxin

    2017-01-01

    To delicately track the Li-ion transport in SPEs under an external electric field (EF) is a big challenge, considering the limitation of most spectroscopic methods to monitor the real-time conformational changes and track the dynamic process. Herein, real-time Li-ion transition behavior and transport dynamics in typical poly(vinyl alcohol)/LiClO4 electrolytes under an external EF have been studied by combining time-resolved Fourier transform infrared (FTIR) with two-dimensional correlation FTIR spectroscopy. Results show that no migration of Li-ions has been detected when the time scale of the EF loading is at nanosecond (less than 200 ns). However, for the first time, Li-ions have been found to significantly transfer along the EF direction as the time scale enhances to microsecond order of magnitude and the migration period is less than 10 microseconds. The Li+ migration in the SPEs under an EF is a complicated process including quasi-periodic dissociation and coordination effects between Li-ion carriers and polymeric chains. PMID:28378837

  7. Real-time tracking the Li(+)-ion transition behavior and dynamics in solid Poly(vinyl alcohol)/LiClO4 electrolytes.

    PubMed

    Bao, Lixia; Zou, Xin; Luo, Xin; Pu, Yanlei; Wang, Jiliang; Lei, Jingxin

    2017-04-05

    To delicately track the Li-ion transport in SPEs under an external electric field (EF) is a big challenge, considering the limitation of most spectroscopic methods to monitor the real-time conformational changes and track the dynamic process. Herein, real-time Li-ion transition behavior and transport dynamics in typical poly(vinyl alcohol)/LiClO4 electrolytes under an external EF have been studied by combining time-resolved Fourier transform infrared (FTIR) with two-dimensional correlation FTIR spectroscopy. Results show that no migration of Li-ions has been detected when the time scale of the EF loading is at nanosecond (less than 200 ns). However, for the first time, Li-ions have been found to significantly transfer along the EF direction as the time scale enhances to microsecond order of magnitude and the migration period is less than 10 microseconds. The Li(+) migration in the SPEs under an EF is a complicated process including quasi-periodic dissociation and coordination effects between Li-ion carriers and polymeric chains.

  8. Structural and Conductivity Studies on Lanthanum Doped LiNiPO4 Prepared by Polyol Method

    NASA Astrophysics Data System (ADS)

    Karthickprabhu, S.; Hirankumar, G.; Maheswaran, A.; Bella, R. S. Daries; Sanjeeviraja, C.

    2013-07-01

    Pure and Lanthanum doped LiNiPO4 (with different Molar concentrations) have been prepared by polyol method using 1,2 propanediol as a polyol medium. XRD analysis reveal that sample calcined at 650°C for 6 hrs shows good crystalline nature with orthorhombic structure and this result is consistent with TG/DTA result. It is found that the conductivity enhances upon doping of Lanthanum while backhoprate decreases compared with pure LiNiPO4. Dielectric studies have also been discussed.

  9. Vanadium doping of LiMnPO4: Vibrational spectroscopy and first-principle studies

    NASA Astrophysics Data System (ADS)

    Kellerman, D.; Medvedeva, N.; Mukhina, N.; Semenova, A.; Baklanova, I.; Perelyaeva, L.; Gorshkov, V.

    2014-01-01

    The samples of pure and 10% vanadium-doped LiMnPO4 have been synthesized by the solid-state reaction technique. The results of Raman and infrared absorption spectroscopy show that the vanadium atoms replace phosphorus giving rise to LiMn(PO4)1-x(VO4)x solid solutions. This conclusion is confirmed by the first-principle studies.

  10. Electrochemical studies of molybdate-doped LiFePO4 as a cathode material in Li-ion batteries.

    PubMed

    Kim, Ketack; Kam, Daewoong; Kim, Yeonjoo; Kim, Sinwoong; Kim, Minsoo; Kim, Hyun-Soo

    2013-05-01

    The use of molybdate as a new anionic dopant that replaces phosphate in LiFePO4 was studied. When a small amount of molybdate (0.5 mol%) was used as a dopant, the olivine structure was maintained, while the lattice volume increased by 0.4%. The expanded volume facilitates ionic transfer, because of which the capacity of doped LiFePO4 at high current discharge rates is higher than that of pure LiFePO4. The discharge value increased by 25.2% at a charge rate of 5 C when the material was doped with 0.5 mol% molybdate ions. The slight expansion of the lattice volume in the olivine structure facilitates a fast redox reaction by lowering the charge transfer resistance. The current values from cyclic voltammetry indicate that the oxidation (charge) process of the cathode material is more improved than the corresponding reduction (discharge) process. Increasing the level of doping beyond 0.5 mol% had no effect on the results. At some discharge rates, the discharge capacity became worse. Because molybdate is divalent while phosphate is trivalent, a large number of molybdate ions in the lattice can exert considerable stress on the structure.

  11. 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.

  12. A study of suppressed formation of low-conductivity phases in doped Li7La3Zr2O12 garnets by in situ neutron diffraction

    DOE PAGES

    Chen, Yan; Rangasamy, Ezhiylmurugan; dela Cruz, Clarina R.; ...

    2015-01-01

    Doped Li7La3Zr2O12 garnets, oxide-based solids with good Li+ conductivity and compatibility, show great potential as leading electrolyte material candidates for all-solid-state lithium ion batteries. Still yet, the conductive bulk usually suffers from the presence of secondary phases and the transition towards a low-conductivity tetragonal phase during synthesis. Dopants are designed to stabilize the high-conductive cubic phase and suppress the formation of the low-conductivity phases. In situ neutron diffraction enables a direct observation of the doping effects by monitoring the phase evolutions during garnet synthesis. It reveals the reaction mechanism involving the temporary presence of intermediate phases. The off-stoichiometry due tomore » the liquid Li2CO3 evaporation leads to the residual of the low-conductivity intermediate phase in the as-synthesized bulk. Appropriate doping of an active element may alter the component of the intermediate phases and promote the completion of the reaction. While the dopants aid to stabilize most of the cubic phase, a small amount of tetragonal phase tends to form under a diffusion process. Lastly, the in situ observations provide the guideline of process optimization to suppress the formation of unwanted low-conductivity phases.« less

  13. X-ray absorption spectroscopy of LiBF 4 in propylene carbonate. A model lithium ion battery electrolyte

    DOE PAGES

    Smith, Jacob W.; Lam, Royce K.; Sheardy, Alex T.; ...

    2014-08-20

    Since their introduction into the commercial marketplace in 1991, lithium ion batteries have become increasingly ubiquitous in portable technology. Nevertheless, improvements to existing battery technology are necessary to expand their utility for larger-scale applications, such as electric vehicles. Advances may be realized from improvements to the liquid electrolyte; however, current understanding of the liquid structure and properties remains incomplete. X-ray absorption spectroscopy of solutions of LiBF4 in propylene carbonate (PC), interpreted using first-principles electronic structure calculations within the eXcited electron and Core Hole (XCH) approximation, yields new insight into the solvation structure of the Li+ ion in this model electrolyte.more » By generating linear combinations of the computed spectra of Li+-associating and free PC molecules and comparing to the experimental spectrum, we find a Li+–solvent interaction number of 4.5. This result suggests that computational models of lithium ion battery electrolytes should move beyond tetrahedral coordination structures.« less

  14. High Performance C/S Composite Cathodes with Conventional Carbonate-Based Electrolytes in Li-S Battery

    PubMed Central

    Zheng, Shiyou; Han, Pan; Han, Zhuo; Zhang, Huijuan; Tang, Zhihong; Yang, Junhe

    2014-01-01

    High stable C/S composites are fabricated by a novel high-temperature sulfur infusion into micro-mesoporous carbon method following with solvent cleaning treatment. The C/S composite cathodes show high Coulombic efficiency, long cycling stability and good rate capability in the electrolyte of 1.0 M LiPF6 + EC/DEC (1:1 v/v), for instance, the reversible capacity of the treated C/S-50 (50% S) cathode retains around 860 mAh/g even after 500 cycles and the Coulombic efficiency is close to 100%, which demonstrates the best electrochemical performance of carbon-sulfur composite cathodes using the carbonate-based electrolyte reported to date. It is believed that the chemical bond of C-S is responsible for the superior electrochemical properties in Li-S battery, that is, the strong interaction between S and carbon matrix significantly improves the conductivity of S, effectively buffers the structural strain/stress caused by the large volume change during lithiation/delithiation, completely eliminates the formation of high-order polysulfide intermediates, and substantially avoids the shuttle reaction and the side reaction between polysulfide anions and carbonate solvent, and thus enables the C/S cathode to use conventional carbonate-based electrolytes and achieve outstanding electrochemical properties in Li-S battery. The results may substantially contribute to the progress of the Li-S battery technology. PMID:24776750

  15. Corrosion evaluation of zirconium doped oxide coatings on aluminum formed by plasma electrolytic oxidation.

    PubMed

    Bajat, Jelena; Mišković-Stanković, Vesna; Vasilić, Rastko; Stojadinović, Stevan

    2014-01-01

    The plasma electrolytic oxidation (PEO) of aluminum in sodium tungstate (Na(2)WO(4) · (2)H(2)O) and Na(2)WO(4) · (2)H(2)O doped with Zr was analyzed in order to obtain oxide coatings with improved corrosion resistance. The influence of current density in PEO process and anodization time was investigated, as well as the influence of Zr, with the aim to find out how they affect the chemical content, morphology, surface roughness, and corrosion stability of oxide coatings. It was shown that the presence of Zr increases the corrosion stability of oxide coatings for all investigated PEO times. Evolution of EIS spectra during the exposure to 3% NaCl, as a strong corrosive agent, indicated the highest corrosion stability for PEO coating formed on aluminum at 70 mA/cm(2) for 2 min in a zirconium containing electrolyte.

  16. Improved Li storage performance in SnO2 nanocrystals by a synergetic doping.

    PubMed

    Wan, Ning; Lu, Xia; Wang, Yuesheng; Zhang, Weifeng; Bai, Ying; Hu, Yong-Sheng; Dai, Sheng

    2016-01-06

    Tin dioxide (SnO2) is a widely investigated lithium (Li) storage material because of its easy preparation, two-step storage mechanism and high specific capacity for lithium-ion batteries (LIBs). In this contribution, a phase-pure cobalt-doped SnO2 (Co/SnO2) and a cobalt and nitrogen co-doped SnO2 (Co-N/SnO2) nanocrystals are prepared to explore their Li storage behaviors. It is found that the morphology, specific surface area, and electrochemical properties could be largely modulated in the doped and co-doped SnO2 nanocrystals. Gavalnostatic cycling results indicate that the Co-N/SnO2 electrode delivers a specific capacity as high as 716 mAh g(-1) after 50 cycles, and the same outstanding rate performance can be observed in subsequent cycles due to the ionic/electronic conductivity enhancement by co-doping effect. Further, microstructure observation indicates the existence of intermediate phase of Li3N with high ionic conductivity upon cycling, which probably accounts for the improvements of Co-N/SnO2 electrodes. The method of synergetic doping into SnO2 with Co and N, with which the electrochemical performances is enhanced remarkably, undoubtedly, will have an important influence on the material itself and community of LIBs as well.

  17. Improved Li storage performance in SnO2 nanocrystals by a synergetic doping

    DOE PAGES

    Wan, Ning; Lu, Xia; Wang, Yuesheng; ...

    2016-01-06

    Tin dioxide (SnO2) is a widely investigated lithium (Li) storage material because of its easy preparation, two-step storage mechanism and high specific capacity for lithium-ion batteries (LIBs). In this contribution, a phase-pure cobalt-doped SnO2 (Co/SnO2) and a cobalt and nitrogen co-doped SnO2 (Co-N/SnO2) nanocrystals are prepared to explore their Li storage behaviors. It is found that the morphology, specific surface area, and electrochemical properties could be largely modulated in the doped and co-doped SnO2 nanocrystals. Gavalnostatic cycling results indicate that the Co-N/SnO2 electrode delivers a specific capacity as high as 716 mAh g–1 after 50 cycles, and the same outstandingmore » rate performance can be observed in subsequent cycles due to the ionic/electronic conductivity enhancement by co-doping effect. Further, microstructure observation indicates the existence of intermediate phase of Li3N with high ionic conductivity upon cycling, which probably accounts for the improvements of Co-N/SnO2 electrodes. Furthermore, we find that the method of synergetic doping into SnO2 with Co and N, with which the electrochemical performances is enhanced remarkably, undoubtedly, will have an important influence on the material itself and community of LIBs as well.« less

  18. Improved Li storage performance in SnO2 nanocrystals by a synergetic doping

    PubMed Central

    Wan, Ning; Lu, Xia; Wang, Yuesheng; Zhang, Weifeng; Bai, Ying; Hu, Yong-Sheng; Dai, Sheng

    2016-01-01

    Tin dioxide (SnO2) is a widely investigated lithium (Li) storage material because of its easy preparation, two-step storage mechanism and high specific capacity for lithium-ion batteries (LIBs). In this contribution, a phase-pure cobalt-doped SnO2 (Co/SnO2) and a cobalt and nitrogen co-doped SnO2 (Co-N/SnO2) nanocrystals are prepared to explore their Li storage behaviors. It is found that the morphology, specific surface area, and electrochemical properties could be largely modulated in the doped and co-doped SnO2 nanocrystals. Gavalnostatic cycling results indicate that the Co-N/SnO2 electrode delivers a specific capacity as high as 716 mAh g−1 after 50 cycles, and the same outstanding rate performance can be observed in subsequent cycles due to the ionic/electronic conductivity enhancement by co-doping effect. Further, microstructure observation indicates the existence of intermediate phase of Li3N with high ionic conductivity upon cycling, which probably accounts for the improvements of Co-N/SnO2 electrodes. The method of synergetic doping into SnO2 with Co and N, with which the electrochemical performances is enhanced remarkably, undoubtedly, will have an important influence on the material itself and community of LIBs as well. PMID:26733355

  19. Energetics of Intermediate Temperature Solid Oxide Fuel Cell Electrolytes: Singly and Doubly doped Ceria Systems

    NASA Astrophysics Data System (ADS)

    Buyukkilic, Salih

    Solid oxide fuel cells (SOFCs) have potential to convert chemical energy directly to electrical energy with high efficiency, with only water vapor as a by-product. However, the requirement of extremely high operating temperatures (~1000 °C) limits the use of SOFCs to only in large scale stationary applications. In order to make SOFCs a viable energy solution, enormous effort has been focused on lowering the operating temperatures below 700 °C. A low temperature operation would reduce manufacturing costs by slowing component degradation, lessening thermal mismatch problems, and sharply reducing costs of operation. In order to optimize SOFC applications, it is critical to understand the thermodynamic stabilities of electrolytes since they directly influence device stability, sustainability and performance. Rare-earth doped ceria electrolytes have emerged as promising materials for SOFC applications due to their high ionic conductivity at the intermediate temperatures (500--700 °C). However there is a fundamental lack of understanding regarding their structure, thermodynamic stability and properties. Therefore, the enthalpies of formation from constituent oxides and ionic conductivities were determined to investigate a relationship between the stability, composition, structural defects and ionic conductivity in rare earth doped ceria systems. For singly doped ceria electrolytes, we investigated the solid solution phase of bulk Ce1-xLnxO2-0.5x where Ln = Sm and Nd (0 ≤ x ≤ 0.30) and analyzed their enthalpies of formation, mixing and association, and bulk ionic conductivities while considering cation size mismatch and defect associations. It was shown that for ambient temperatures in the dilute dopant region, the positive heat of formation reaches a maximum as the system becomes increasingly less stable due to size mismatch. In concentrated region, stabilization to a certain solubility limit was observed probably due to the defect association of trivalent cations

  20. NMR spin-lattice relaxation study of 7Li and 93Nb nuclei in Ti- or Fe-doped LiNbO3:Mg single crystals

    NASA Astrophysics Data System (ADS)

    Yeom, Tae Ho; Lim, Ae Ran

    2016-04-01

    In this study, to understand the effects of paramagnetic impurities, we investigated the temperature dependent of the spin-lattice relaxation times of pure LiNbO3, LiNbO3:Mg, LiNbO3:Mg/Ti, LiNbO3:Mg/Fe, and LiNbO3:Mg/Fe (thermally treated at 500°C) single crystals. The results for the LiNbO3:Mg single crystals doped with Fe3+ or Ti3+ are discussed with respect to the site distribution and atomic mobility of Li and Nb. In addition, the effects of a thermal treatment on LiNbO3:Mg/Fe single crystals were examined based on the T1 analysis of 7Li and 93Nb. It was found that the presence of impurities in the crystals induced systematic changes of activation energies concerning atomic mobility.

  1. Electrolytes

    MedlinePlus

    ... part of blood that doesn't contain cells. Sodium, potassium, and chloride levels can also be measured as part of ... in urine. It test the levels of calcium, chloride, potassium, sodium, and other electrolytes. References Chernecky CC, Berger BJ. ...

  2. Study of gadolinia-doped ceria solid electrolyte surface by XPS

    SciTech Connect

    Datta, Pradyot Majewski, Peter; Aldinger, Fritz

    2009-02-15

    Gadolinia-doped ceria (CGO) is an important material to be used as electrolyte for solid oxide fuel cell for intermediate temperature operation. Ceria doped with 10 mol% gadolinia (Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95}) was prepared by conventional solid state synthesis and found to be single phase by room temperature X-ray diffraction (XRD). The chemical states of the surface of the prepared sample were analyzed by X-ray photoelectron spectroscopy (XPS). Though Gd was present in its characteristic chemical state, Ce was found in both Ce{sup 4+} and Ce{sup 3+} states. Presence of Ce{sup 3+} state was ascribed to the differential yield of oxygen atoms in the sputtering process.

  3. Ag nanoparticles-anchored reduced graphene oxide catalyst for oxygen electrode reaction in aqueous electrolytes and also a non-aqueous electrolyte for Li-O2 cells.

    PubMed

    Kumar, Surender; Selvaraj, C; Scanlon, L G; Munichandraiah, N

    2014-11-07

    Silver nanoparticles-anchored reduced graphene oxide (Ag-RGO) is prepared by simultaneous reduction of graphene oxide and Ag(+) ions in an aqueous medium by ethylene glycol as the reducing agent. Ag particles of average size of 4.7 nm were uniformly distributed on the RGO sheets. Oxygen reduction reaction (ORR) is studied on Ag-RGO catalyst in both aqueous and non-aqueous electrolytes by using cyclic voltammetry and rotating disk electrode techniques. As the interest in non-aqueous electrolyte is to study the catalytic performance of Ag-RGO for rechargeable Li-O2 cells, these cells are assembled and characterized. Li-O2 cells with Ag-RGO as the oxygen electrode catalyst are subjected to charge-discharge cycling at several current densities. A discharge capacity of 11 950 mA h g(-1) (11.29 mA h cm(-2)) is obtained initially at low current density. Although there is a decrease in the capacity on repeated discharge-charge cycling initially, a stable capacity is observed for about 30 cycles. The results indicate that Ag-RGO is a suitable catalyst for rechargeable Li-O2 cells.

  4. Real-time mass spectroscopy analysis of Li-ion battery electrolyte degradation under abusive thermal conditions

    NASA Astrophysics Data System (ADS)

    Gaulupeau, B.; Delobel, B.; Cahen, S.; Fontana, S.; Hérold, C.

    2017-02-01

    The lithium-ion batteries are widely used in rechargeable electronic devices. The current challenges are to improve the capacity and safety of these systems in view of their development to a larger scale, such as for their application in electric and hybrid vehicles. Lithium-ion batteries use organic solvents because of the wide operating voltage. The corresponding electrolytes are usually based on combinations of linear, cyclic alkyl carbonates and a lithium salt such as LiPF6. It has been reported that in abusive thermal conditions, a catalytic effect of the cathode materials lead to the formation fluoro-organics compounds. In order to understand the degradation phenomenon, the study at 240 °C of the interaction between positive electrode materials (LiCoO2, LiNi1/3Mn1/3Co1/3O2, LiMn2O4 and LiFePO4) and electrolyte in dry and wet conditions has been realized by an original method which consists in analyzing by mass spectrometry in real time the volatile molecules produced. The evolution of specific gases channels coupled to the NMR reveal the formation of rarely discussed species such as 2-fluoroethanol and 1,4-dioxane. Furthermore, it appears that the presence of water or other protic impurities greatly influence their formation.

  5. Fabrication of multi-non-metal-doped TiO{sub 2} nanotubes by anodization in mixed acid electrolyte

    SciTech Connect

    Lei Lecheng Su Yaling; Zhou Minghua; Zhang Xingwang; Chen Xiuqin

    2007-12-04

    Multi-non-metal-doped TiO{sub 2} nanotubes were fabricated by electrochemical anodization of Ti in the mixed acid electrolyte of C{sub 2}H{sub 2}O{sub 4}.2H{sub 2}O and HIO{sub 3} containing NH{sub 4}F. The samples were annealed in air and characterized by FE-SEM, XRD, XPS and DRS. The results indicate non-metals of N, F and I are successfully doped into TiO{sub 2} nanotubes in aqueous solution by adjusting the electrolyte composition. The multi-non-metal-doped samples display a significant visible-light response. Additionally, the atomic concentration of non-metals is closely related with the electrolyte composition.

  6. Chemical stability and Ce doping of LiMgAlF6 neutron scintillator

    DOE PAGES

    Du, M. H.

    2014-11-13

    We perform density functional calculations to investigate LiMgAlF6 as a potential neutron scintillator material. The calculations of enthalpy of formation and phase diagram show that single-phase LiMgAlF6 can be grown but it should be more difficult than growing LiCaAlF6 and LiSrAlF6. Moreover, the formation energy calculations for substitutional Ce show that the concentration of Ce on the Al site is negligible but a high concentration (>1 at.%) of Ce on the Mg site is attainable provided that the Fermi level is more than 5 eV lower than the conduction band minimum. Acceptor doping should promote Ce incorporation in LiMgAlF6.

  7. Chemical stability and Ce doping of LiMgAlF6 neutron scintillator

    SciTech Connect

    Du, M. H.

    2014-11-13

    We perform density functional calculations to investigate LiMgAlF6 as a potential neutron scintillator material. The calculations of enthalpy of formation and phase diagram show that single-phase LiMgAlF6 can be grown but it should be more difficult than growing LiCaAlF6 and LiSrAlF6. Moreover, the formation energy calculations for substitutional Ce show that the concentration of Ce on the Al site is negligible but a high concentration (>1 at.%) of Ce on the Mg site is attainable provided that the Fermi level is more than 5 eV lower than the conduction band minimum. Acceptor doping should promote Ce incorporation in LiMgAlF6.

  8. Effect of LiNO3 additive and pyrrolidinium ionic liquid on the solid electrolyte interphase in the lithium-sulfur battery

    NASA Astrophysics Data System (ADS)

    Barghamadi, Marzieh; Best, Adam S.; Bhatt, Anand I.; Hollenkamp, Anthony F.; Mahon, Peter J.; Musameh, Mustafa; Rüther, Thomas

    2015-11-01

    The lithium-sulfur (Li-S) battery in which the ionic liquid (IL) C4mpyr-TFSI is a major component of the electrolyte has attracted much attention by researchers due to the ability of the IL to suppress the polysulfide shuttle effect, combined with advantageous properties of thermal, chemical and electrochemical stability. In a largely parallel stream of research, LiNO3 has come to be known as an additive for improving Li-S battery performance through its influence on protecting the lithium anode and beneficial interaction with the polysulfide shuttle. In this work a deeper understanding is sought of the combined effects of LiNO3 and C4mpyr-TFSI on the factors that impact Li-S cell performance. Specifically, we investigate the formation of the protective surface film on lithium anode and results are compared with those for a typical organic electrolyte for the Li-S battery, DOL:DME. Electrochemical impedance spectroscopy (EIS) confirms that the LiNO3 additive is vital to achieving acceptable levels of performance with the organic electrolyte. Although LiNO3 improves the performance of a battery assembled with IL containing electrolyte, it shows a higher impact in the organic electrolyte based battery. Furthermore X-ray photoelectron spectroscopy (XPS) spectra confirm the participation of C4mpyr-TFSI on the formation of the interphase layer on the anode.

  9. In situ Electrochemical-AFM Study of LiFePO4 Thin Film in Aqueous Electrolyte.

    PubMed

    Wu, Jiaxiong; Cai, Wei; Shang, Guangyi

    2016-12-01

    Lithium-ion (Li-ion) batteries have been widely used in various kinds of electronic devices in our daily life. The use of aqueous electrolyte in Li-ion battery would be an alternative way to develop low cost and environmentally friendly batteries. In this paper, the lithium iron phosphate (LiFePO4) thin film cathode for the aqueous rechargeable Li-ion battery is prepared by radio frequency magnetron sputtering deposition method. The XRD, SEM, and AFM results show that the film is composed of LiFePO4 grains with olivine structure and the average size of 100 nm. Charge-discharge measurements at current density of 10 μAh cm(-2) between 0 and 1 V show that the LiFePO4 thin film electrode is able to deliver an initial discharge capacity of 113 mAh g(-1). Specially, the morphological changes of the LiFePO4 film electrode during charge and discharge processes were investigated in aqueous environment by in situ EC-AFM, which is combined AFM with chronopotentiometry method. The changes in grain area are measured, and the results show that the size of the grains decreases and increases during the charge and discharge, respectively; the relevant mechanism is discussed.

  10. In situ Electrochemical-AFM Study of LiFePO4 Thin Film in Aqueous Electrolyte

    NASA Astrophysics Data System (ADS)

    Wu, Jiaxiong; Cai, Wei; Shang, Guangyi

    2016-04-01

    Lithium-ion (Li-ion) batteries have been widely used in various kinds of electronic devices in our daily life. The use of aqueous electrolyte in Li-ion battery would be an alternative way to develop low cost and environmentally friendly batteries. In this paper, the lithium iron phosphate (LiFePO4) thin film cathode for the aqueous rechargeable Li-ion battery is prepared by radio frequency magnetron sputtering deposition method. The XRD, SEM, and AFM results show that the film is composed of LiFePO4 grains with olivine structure and the average size of 100 nm. Charge-discharge measurements at current density of 10 μAh cm-2 between 0 and 1 V show that the LiFePO4 thin film electrode is able to deliver an initial discharge capacity of 113 mAh g-1. Specially, the morphological changes of the LiFePO4 film electrode during charge and discharge processes were investigated in aqueous environment by in situ EC-AFM, which is combined AFM with chronopotentiometry method. The changes in grain area are measured, and the results show that the size of the grains decreases and increases during the charge and discharge, respectively; the relevant mechanism is discussed.

  11. Defect assisted saturable absorption characteristics in Al and Li doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    K. M., Sandeep; Bhat, Shreesha; S. M., Dharmaprakash; P. S., Patil; Byrappa, K.

    2016-09-01

    The influence of different doping ratios of Al and Li on the nonlinear optical properties, namely, a two-photon absorption and a nonlinear refraction using single beam Z-scan technique, of nano-crystalline ZnO thin films has been investigated in the present study. A sol-gel spin-coated pure ZnO, Al-doped ZnO (AZO), and Li-doped ZnO (LZO) thin films have been prepared. The stoichiometric deviations induced by the occupancy of Al3+ and Li+ ions at the interstitial sites injects the compressive stress in the AZO and LZO thin films, respectively, while the extended defect states below the conduction band leads to a redshift of energy band gap in the corresponding films as compared to pure ZnO thin film. Switching from an induced absorption in ZnO and 1 at. wt. % doped AZO and LZO films to a saturable absorption (SA) in 2 at. wt. % doped AZO and LZO films has been observed, and it is attributed to the saturation of a linear absorption of the defect states. The closed aperture Z-scan technique revealed the self-focusing (a positive nonlinear refractive index) in all the films, which emerge out of the thermo-optical effects due to the continuous illumination of laser pulses. A higher third-order nonlinear optical susceptibility χ(3) of the order 10-3 esu has been observed in all the films.

  12. Ionically conducting PVA-LiClO4 gel electrolyte for high performance flexible solid state supercapacitors.

    PubMed

    Chodankar, Nilesh R; Dubal, Deepak P; Lokhande, Abhishek C; Lokhande, Chandrakant D

    2015-12-15

    The synthesis of polymer gel electrolyte having high ionic conductivity, excellent compatibility with active electrode material, mechanical tractability and long life is crucial to obtain majestic electrochemical performance for flexible solid state supercapacitors (FSS-SCs). Our present work describes effect of different polymers gel electrolytes on electrochemical properties of MnO2 based FSS-SCs device. It is revealed that, MnO2-FSS-SCs with polyvinyl alcohol (PVA)-Lithium perchlorate (LiClO4) gel electrolyte demonstrate excellent electrochemical features such as maximum operating potential window (1.2V), specific capacitance of 112Fg(-1) and energy density of 15Whkg(-1) with extended cycling stability up to 2500CV cycles. Moreover, the calendar life suggests negligible decrease in the electrochemical performance of MnO2-FSS-SCs after 20days.

  13. Synthesis of polymer electrolyte membranes from cellulose acetate/poly(ethylene oxide)/LiClO{sub 4} for lithium ion battery application

    SciTech Connect

    Nurhadini, Arcana, I Made

    2015-09-30

    This study was conducted to determine the effect of cellulose acetate on poly(ethylene oxide)-LiClO{sub 4} membranes as the polymer electrolyte. Cellulose acetate is used as an additive to increase ionic conductivity and mechanical property of polymer electrolyte membranes. The increase the percentage of cellulose acetate in membranes do not directly effect on the ionic conductivity, and the highest ionic conductivity of membranes about 5,7 × 10{sup −4} S/cm was observed in SA/PEO/LiClO{sub 4} membrane with cellulose ratio of 10-25% (w/w). Cellulose acetate in membranes increases mechanical strength of polymer electrolyte membranes. Based on TGA analysis, this polymer electrolyte thermally is stable until 270 °C. The polymer electrolyte membrane prepared by blending the cellulose acetate, poly(ethylene oxide), and lithium chlorate could be potentially used as a polymer electrolyte for lithium ion battery application.

  14. Synthesis of polymer electrolyte membranes from cellulose acetate/poly(ethylene oxide)/LiClO4 for lithium ion battery application

    NASA Astrophysics Data System (ADS)

    Nurhadini, Arcana, I. Made

    2015-09-01

    This study was conducted to determine the effect of cellulose acetate on poly(ethylene oxide)-LiClO4 membranes as the polymer electrolyte. Cellulose acetate is used as an additive to increase ionic conductivity and mechanical property of polymer electrolyte membranes. The increase the percentage of cellulose acetate in membranes do not directly effect on the ionic conductivity, and the highest ionic conductivity of membranes about 5,7 × 10-4 S/cm was observed in SA/PEO/LiClO4 membrane with cellulose ratio of 10-25% (w/w). Cellulose acetate in membranes increases mechanical strength of polymer electrolyte membranes. Based on TGA analysis, this polymer electrolyte thermally is stable until 270 °C. The polymer electrolyte membrane prepared by blending the cellulose acetate, poly(ethylene oxide), and lithium chlorate could be potentially used as a polymer electrolyte for lithium ion battery application.

  15. Transport Properties Of PbI2 Doped Silver Oxysalt Based Amorphous Solid Electrolytes

    NASA Astrophysics Data System (ADS)

    Shrisanjaykumar Jayswal, Manishkumar

    Solid electrolytes are a class of materials that conduct electricity by means of motion of ions like Ag+, Na+, Li +, Cu+, H+, F-, O -2 etc. in solid phase. The host materials include crystalline, polycrystalline, glasses, polymers and composites. Ion conducting glasses are one of the most sought after solid electrolytes that are useful in various electrochemical applications like solid state batteries, gas sensors, supercapacitors, electrochromic devices, to name a few. Since the discovery of fast silver ion transport in silver oxyhalide glasses at the end of the 1960s, many glasses showing large ionic conductivity up to 10-4 10-2 S/cm at room temperature have been developed, chiefly silver and copper ion conductors. The silver ion conducting glasses owe their high ionic conductivity mainly to stabilized alpha-AgI. AgI, as we know, undergoes a structural phase transition from wurtzite (beta phase) at room temperature to body centered cubic (alpha phase) structure at temperatures higher than 146 °C. The alpha-AgI possesses approximately six order of higher ionic conductivity than beta-AgI. The high ionic conductivity of alpha-AgI is attributed to its molten sublattice type of structure, which facilitates easy Ag+ ion migration, like a liquid. And hence, several attempts have been made to stabilize it at room temperature in crystalline as well as non-crystalline hosts like oxide and non-oxide glasses. Recently, in order to stabilize AgI in glasses, instead of directly doping it, indirect routes have also been explored. Where, a metal iodide salt along with silver oxide or silver phosphate is taken and an exchange reaction permitted by Hard and Soft, Acid and Base (HSAB) principle occurs between the two and AgI and metal oxide form in the glass forming melt. Work done in the present thesis has been organized in seven chapters as follows: Chapter 1: A review and background information of different solid electrolyte materials and their development is presented. Along

  16. The anomaly Cu doping effects on LiFeAs superconductors

    NASA Astrophysics Data System (ADS)

    Xing, L. Y.; Miao, H.; Wang, X. C.; Ma, J.; Liu, Q. Q.; Deng, Z.; Ding, H.; Jin, C. Q.

    2014-10-01

    The Cu substitution effect on the superconductivity of LiFeAs has been studied in comparison with Co/Ni substitution. It is found that the shrinking rate of the lattice parameter c for Cu substitution is much smaller than that of Co/Ni substitution. This is in conjugation with the observation of ARPES that shows almost the same electron and hole Fermi surfaces (FSs) size for undoped and Cu substituted LiFeAs sample, except for a very small hole band sinking below Fermi level with doping. This indicates that there is little doping effect at Fermi surface by Cu substitution, in sharp contrast to the more effective carrier doping effect by Ni or Co.

  17. Predicting solvent stability in aprotic electrolyte Li-air batteries: nucleophilic substitution by the superoxide anion radical (O2(•-)).

    PubMed

    Bryantsev, Vyacheslav S; Giordani, Vincent; Walker, Wesley; Blanco, Mario; Zecevic, Strahinja; Sasaki, Kenji; Uddin, Jasim; Addison, Dan; Chase, Gregory V

    2011-11-10

    There is increasing evidence that cyclic and linear carbonates, commonly used solvents in Li ion battery electrolytes, are unstable in the presence of superoxide and thus are not suitable for use in rechargeable Li-air batteries employing aprotic electrolytes. A detailed understanding of related decomposition mechanisms provides an important basis for the selection and design of stable electrolyte materials. In this article, we use density functional theory calculations with a Poisson-Boltzmann continuum solvent model to investigate the reactivity of several classes of aprotic solvents in nucleophilic substitution reactions with superoxide. We find that nucleophilic attack by O(2)(•-) at the O-alkyl carbon is a common mechanism of decomposition of organic carbonates, sulfonates, aliphatic carboxylic esters, lactones, phosphinates, phosphonates, phosphates, and sulfones. In contrast, nucleophilic reactions of O(2)(•-) with phenol esters of carboxylic acids and O-alkyl fluorinated aliphatic lactones proceed via attack at the carbonyl carbon. Chemical functionalities stable against nucleophilic substitution by superoxide include N-alkyl substituted amides, lactams, nitriles, and ethers. The results establish that solvent reactivity is strongly related to the basicity of the organic anion displaced in the reaction with superoxide. Theoretical calculations are complemented by cyclic voltammetry to study the electrochemical reversibility of the O(2)/O(2)(•-) couple containing tetrabutylammonium salt and GCMS measurements to monitor solvent stability in the presence of KO(2)(•) and a Li salt. These experimental methods provide efficient means for qualitatively screening solvent stability in Li-air batteries. A clear correlation between the computational and experimental results is established. The combination of theoretical and experimental techniques provides a powerful means for identifying and designing stable solvents for rechargeable Li-air batteries.

  18. The effect of porosity on performance of phosphoric acid doped polybenzimidazole polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Celik, Muhammet; Genc, Gamze; Elden, Gulsah; Yapici, Huseyin

    2016-03-01

    A polybenzimidazole (PBI) based polymer electrolyte fuel cells, which called high temperature polymer electrolyte fuel cells (HT-PEMS), operate at higher temperatures (120-200°C) than conventional PEM fuel cells. Although it is known that HT-PEMS have some of the significant advantages as non-humidification requirements for membrane and the lack of liquid water at high temperature in the fuel cell, the generated water as a result of oxygen reduction reaction causes in the degradation of these systems. The generated water absorbed into membrane side interacts with the hydrophilic PBI matrix and it can cause swelling of membrane, so water transport mechanism in a membrane electrode assembly (MEA) needs to be well understood and water balance must be calculated in MEA. Therefore, the water diffusion transport across the electrolyte should be determined. In this study, various porosity values of gas diffusion layers are considered in order to investigate the effects of porosity on the water management for two phase flow in fuel cell. Two-dimensional fuel cell with interdigitated flow-field is modelled using COMSOL Multiphysics 4.2a software. The operating temperature and doping level is selected as 160°C and 6.75mol H3PO4/PBI, respectively.

  19. Proton conducting polymer electrolytes based on KH2PO4 doped PVA

    NASA Astrophysics Data System (ADS)

    Uddin, Md Jamal; Sarkar, S. C.; Chaudhuri, B. K.

    2012-06-01

    Transparent and anhydrous proton conducting polymer electrolytes based on polyvinyl alcohol (PVA)/potassium dihydrogen phosphate (KH2PO4) with different concentrations of KDP (φKDP) were prepared by solution casting technique. Ionic conductivity of the polymer electrolytes, studied by the complex impedance method, increases with increasing temperature as well as phosphate doping-level and then decreases with increasing phosphate (φC>2.5wt%KDP). The maximum ionic conductivity (3.7 × 10-4 S/cm) and minimum activation energy (˜0.25eV) was obtained at 303K for this typical concentration φC. The temperature dependence of ionic conductivity of the prepared polymer electrolytes obeys Arrhenius law. Moreover, the PVA/KDP composite exhibiting high dielectric constante ɛ' ˜ 430 (80 times higher compared to pure PVA) near the percolation threshold (φC =2.5wt% KDP) with low dielectric losses (˜0.15) at 1 kHz and room temperature might be suitable for technological applications.

  20. Role of doping, gelation and phase suppression on conductivity in polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Rivera Bengoechea, Manuel

    Polymer Ionics, a sub-field of solid state ionics, is a relative latecomer in the search of non-metallic conducting materials that can be utilized in the fabrication of all-solid-state electrochemical cells. Conducting polymers are particularly suited to be used in conjunction with the insertion electrode materials that solid state ionics has developed by providing the necessary flexibility needed to accommodate volume changes. In this thesis we investigate doped polyethylene oxide (PEO-LiCF 3SO3) and the effects of gelation on charge transport and solid phase formation. Broadband dielectric spectroscopy (BDS) and differential scanning calorimetry (DSC) measurements were performed and our data reveals an increase in conductivity approximately 5 times larger at room temperature and a complete suppression of crystallization upon gelation. We also investigated via BDS emeraldine base polyaniline (PANiEB), a form of polyaniline which can be made conductive by doping and consists of segments which are half oxidized and half reduced. Micro phase separation in PANiEB (appearance of segments fully oxidized or fully reduced) reduces the doping effectiveness. We were able to suppress this micro phase separation by means of confinement of the material in an anapore membrane potentially optimizing the doping effectiveness.

  1. A Cross-Linking Succinonitrile-Based Composite Polymer Electrolyte with Uniformly Dispersed Vinyl-Functionalized SiO2 Particles for Li-Ion Batteries.

    PubMed

    Liu, Kai; Ding, Fei; Liu, Jiaquan; Zhang, Qingqing; Liu, Xingjiang; Zhang, Jinli; Xu, Qiang

    2016-09-14

    A cross-linking succinonitrile (SN)-based composite polymer electrolyte (referred to as "CLPC-CPE"), in which vinyl-functionalized SiO2 particles connect with trimethylolpropane propoxylate triacrylate (TPPTA) monomers by covalent bonds, was prepared by an ultraviolet irradiation (UV-curing) process successfully. Vinyl-functionalized SiO2 particles may react with TPPTA monomers to form a cross-linking network within the SN-based composite polymer electrolyte under ultraviolet irradiation. Vinyl-functionalized SiO2 particles as the fillers of polymer electrolyte may improve both the thermal stability of CLPC-CPE and interfacial compatibility between CLPC-CPE and electrodes effectively. There is no weight loss for CLPC-CPE until above 230 °C. The ionic conductivity of CLPC-CPE may reach 7.02 × 10(-4) S cm(-1) at 25 °C. CLPC-CPE has no significant oxidation current until up to 4.6 V (vs Li/Li(+)). The cell of LiFePO4/CLPC-CPE/Li has presented superior cycle performance and rate capability. The cell of LiFePO4/CLPC-CPE/Li may deliver a high discharge capacity of 154.4 mAh g(-1) at a rate of 0.1 C after 100 charge-discharge cycles, which is similar than that of the control cell of LiFePO4/liquid electrolyte/Li. Furthermore, the cell of LiFePO4/CLPC-CPE/Li can display a high discharge capacity of 112.7 mAh g(-1) at a rate of 2 C, which is higher than that of the cells assembled with other plastic crystal polymer electrolyte reported before obviously.

  2. Visible-light activity of N-LiInO2: Band structure modifications through interstitial nitrogen doping

    NASA Astrophysics Data System (ADS)

    Xu, Kaiqiang; Xu, Difa; Zhang, Xiangchao; Luo, Zhuo; Wang, Yutang; Zhang, Shiying

    2017-01-01

    Element doping is a promising strategy to improve the photo-response and photocatalytic activity of semiconductor photocatalyst with a wide band gap. To reduce the band gap of LiInO2 that is considered as a novel photocatalyst, nitrogen-doped LiInO2 (N-LiInO2) is successfully fabricated by treating LiInO2 and urea at 200 °C. It is found that interstitial instead of substitutional configurations are formed in the crystal structure of N-LiInO2 due to the low-treating temperature and rich-oxygen conditions. The interstitial N-doping forms a doping state with 0.6 eV above the valence band maximum and a defect state with 0.1 eV below the conduction band minimum, reducing the band gap of LiInO2 from 3.5 to 2.8 eV. N-LiInO2 exhibits higher photocatalytic activity towards methylene blue (MB) degradation under 380 nm light irradiation, which is 1.4 times that of pure LiInO2. The enhanced photocatalytic activity of N-LiInO2 is attributed to the extended light absorption and the improved charge carrier separation, which result in more reactive species participating in the photcatalytic process. This work provides a further understanding on tuning the band structure of semiconductor photocatalyst by N-doping strategies.

  3. Suppression of Lithium Dendrite Formation by Using LAGP-PEO (LiTFSI) Composite Solid Electrolyte and Lithium Metal Anode Modified by PEO (LiTFSI) in All-Solid-State Lithium Batteries.

    PubMed

    Wang, Chunhua; Yang, Yifu; Liu, Xingjiang; Zhong, Hai; Xu, Han; Xu, Zhibin; Shao, Huixia; Ding, Fei

    2017-04-07

    The formation of lithium dendrites is suppressed using a Li1.5Al0.5Ge1.5(PO4)3-poly(ethylene oxide) (LAGP-PEO) composite solid electrolyte and a PEO (lithium bis(trifluoromethane)sulfonimide) [PEO (LiTFSI)]-modified lithium metal anode in all-solid-state lithium batteries. The effects on the anode performance based on the PEO content in the composite solid electrolyte and the molecular weight of PEO used to modify the Li anode are studied. The structure, surface morphology, and stability of the composite solid electrolyte are examined by X-ray diffraction spectroscopy, scanning electron microscopy, and electrochemical tests. Results show that the presence of a PEO-500000(LiTFSI) film on a Li anode results in good mechanical properties and satisfactory interface contact features. The film can also prevent Li from reacting with LAGP. Furthermore, the formation of lithium dendrites can be effectively inhibited as the composite solid electrolyte is combined with the PEO film on the Li anode. The ratio of PEO in the composite solid electrolyte can be reduced to a low level of 1 wt %. PEO remains stable even at a high potential of 5.12 V (vs Li/Li(+)). The assembled Li-PEO (LiTFSI)/LAGP-PEO/LiMn0.8Fe0.2PO4 all-solid-state cell can deliver an initial discharge capacity of 160.8 mAh g(-1) and exhibit good cycling stability and rate performance at 50 °C.

  4. EXAFS simulations in Zn-doped LiNbO3 based on defect calculations

    NASA Astrophysics Data System (ADS)

    Valerio, Mário E. G.; Jackson, Robert A.; Bridges, Frank G.

    2017-02-01

    Lithium niobate, LiNbO3, is an important technological material with good electro-optic, acousto-optic, elasto-optic, piezoelectric and nonlinear properties. EXAFS on Zn-doped LiNbO3 found strong evidences that Zn substitutes primarily at the Li site on highly doped samples. In this work the EXAFS results were revisited using a different approach where the models for simulating the EXAFS results were obtained from the output of defect calculations. The strategy uses the relaxed positions of the ions surrounding the dopants to generate a cluster from where the EXAFS oscillations can be calculated. The defect involves not only the Zn possible substitution at either Li or Nb sites but also the charge compensating defects, when needed. From previous defect modelling, a subset of defects was selected based on the energetics of the defect production in the LiNbO3 lattice. From them, all possible clusters were generated and the simulated EXAFS were computed. The simulated EXAFS were them compared to available EXAFS results in the literature. Based on this comparison different models could be proposed to explain the behaviour of Zn in the LiNbO3 matrix.

  5. Doping of Ion Irradiated Polyethylenterephtalate from Water Solution of LiCl

    NASA Astrophysics Data System (ADS)

    Hnatowicz, V.; Vacík, J.; Ervená, J.; Vorík, V.; Rybka, V.; Fink, D.; Klett, R.

    1997-02-01

    Polyethylenterephtalate foils (10 m thick with the density of = 1.3 g cm - 3) were irradiated with 150 keV Ar+ ions to fluences from 5×1011 to 1×1015 cm - 2 and one year after the irradiation they were exposed to a 5 M water solution of LiCl at the boiling point for times ranging from 15 s up to 8 h. The depth profiles of incorporated Li atoms as a function of the ion fluence and the doping time were determined using the neutron depth profiling technique based on the 6Li(nth, α)3H nuclear reaction. The Li content in the 600 nm thick surface layer achieves saturation very rapidly, already after 15 s doping time, and it exhibits a local, pronounced maximum at 2 or 4 h doping times for the specimens irradiated to fluences below and above 5×1014 cm - 2, respectively. The concentration depth profiles of incorporated Li atoms consist of a pronounced surface component, obviously connected with radiation damages created by the ion irradiation and a long inward tail which is due to regular diffusion in pristine polymer. As a function of ion fluence, the Li content increases up to the fluence of 5×1013 cm - 2 and then declines in most cases. The surface component of the Li depth profiles changes dramatically with increasing ion fluence from bell-shaped ones for fluences below 5×1014 cm×2 to those characterized by a depleted surface layer and a rather sharp concentration maximum at depths significantly exceeding the calculated ion projected range.

  6. Infiltration of Solution-Processable Solid Electrolytes into Conventional Li-Ion-Battery Electrodes for All-Solid-State Li-Ion Batteries.

    PubMed

    Kim, Dong Hyeon; Oh, Dae Yang; Park, Kern Ho; Choi, Young Eun; Nam, Young Jin; Lee, Han Ah; Lee, Sang-Min; Jung, Yoon Seok

    2017-04-05

    Bulk-type all-solid-state lithium-ion batteries (ASLBs) have the potential to be superior to conventional lithium-ion batteries (LIBs) in terms of safety and energy density. Sulfide SE materials are key to the development of bulk-type ASLBs because of their high ionic conductivity (max of ∼10(-2) S cm(-1)) and deformability. However, the severe reactivity of sulfide materials toward common polar solvents and the particulate nature of these electrolytes pose serious complications for the wet-slurry process used to fabricate ASLB electrodes, such as the availability of solvent and polymeric binders and the formation of ionic contacts and networks. In this work, we report a new scalable fabrication protocol for ASLB electrodes using conventional composite LIB electrodes and homogeneous SE solutions (Li6PS5Cl (LPSCl) in ethanol or 0.4LiI-0.6Li4SnS4 in methanol). The liquefied LPSCl is infiltrated into the tortuous porous structures of LIB electrodes and solidified, providing intimate ionic contacts and favorable ionic percolation. The LPSCl-infiltrated LiCoO2 and graphite electrodes show high reversible capacities (141 and 364 mA h g(-1)) at 0.14 mA cm(-2) (0.1 C) and 30 °C, which are not only superior to those for conventional dry-mixed and slurry-mixed ASLB electrodes but also comparable to those for liquid electrolyte cells. Good electrochemical performance of ASLBs employing the LPSCl-infiltrated LiCoO2 and graphite electrodes at 100 °C is also presented, highlighting the excellent thermal stability and safety of ASLBs.

  7. Thin hybrid electrolyte based on garnet-type lithium-ion conductor Li7La3Zr2O12 for 12 V-class bipolar batteries

    NASA Astrophysics Data System (ADS)

    Yoshima, Kazuomi; Harada, Yasuhiro; Takami, Norio

    2016-01-01

    Thin hybrid electrolytes based on lithium-ion conducting ceramics with a few micrometers thickness have been studied in order to be practically applied to 12 V-class bipolar battery with liquid-free and separator-free. A cubic garnet-type Li7La3Zr2O12 (LLZ)-based hybrid electrolyte composed of LLZ particles coated with 4 wt% polyacrylonitrile (PAN)-based gel polymer electrolyte was prepared as the thin electrolyte layer, which reduced the internal resistance of LiMn0.8Fe0.2PO4(LMFP)/Li4Ti5O12(LTO) cells and enabled discharge at low temperatures. The conductivity of the LLZ-based hybrid electrolyte at 25°C was one order of magnitude higher than that of the LLZ solid electrolyte and comparable to that of the PAN-based gel polymer. The activation energy for ionic conductivity of the hybrid electrolyte was significantly smaller than that of the gel polymer electrolyte. The fabricated 12 V-class bipolar LMFP/LTO battery using the thin LLZ-based hybrid electrolyte layer exhibited good performance in terms of discharge rate capability, operating in the wide temperature range of -40°C to 80°C, and charge-discharge cycling comparable to those of conventional lithium-ion batteries.

  8. Role of polar side chains in Li(+) coordination and transport properties of polyoxetane-based polymer electrolytes.

    PubMed

    Sai, Ryansu; Ueno, Kazuhide; Fujii, Kenta; Nakano, Yohei; Shigaki, Naho; Tsutsumi, Hiromori

    2017-02-15

    Lithium ion conducting polymer electrolytes (PEs) have been the subject of intense research for lithium metal battery applications. Here, we investigate the effects of polar side chains on Li(+) coordination and ionic transport properties to gain insights for improving the insufficient conductivity of traditional ether-based solid PEs. Poly(trimethyleneoxide)-based (or polyoxetane-based) polymers with ether or nitrile groups were synthesized by ring-opening polymerization. The thermal, ionic transport, and electrochemical properties and the local structure of Li(+) coordination were studied in the presence of lithium bis(trifluoromethanesulfonyl)amide (LiTFSA). The glass transition temperature (Tg) of the PEs with ether side chains increased with increasing LiTFSA content, whereas the PEs with the nitrile functionality showed the opposite trend at higher salt concentrations. In addition to the unique trend for the Tg values of the PEs in the presence of LiTFSA, the nitrile groups played pivotal roles as coordination sites for Li(+) ions in the first coordination shell and as a polar medium to increase the permittivity of the PEs. These characteristics of the nitrile groups can endow PEs with improved ionic transport properties.

  9. Li+ transport in poly(ethylene oxide) based electrolytes: neutron scattering, dielectric spectroscopy, and molecular dynamics simulations.

    PubMed

    Do, Changwoo; Lunkenheimer, Peter; Diddens, Diddo; Götz, Marion; Weiss, Matthias; Loidl, Alois; Sun, Xiao-Guang; Allgaier, Jürgen; Ohl, Michael

    2013-07-05

    The dynamics of Li(+) transport in polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imde mixtures are investigated by combining neutron spin-echo (NSE) and dielectric spectroscopy with molecular dynamics (MD) simulations. The results are summarized in a relaxation time map covering wide ranges of temperature and time. The temperature dependence of the dc conductivity and the dielectric α relaxation time is found to be identical, indicating a strong coupling between both. The relaxation times obtained from the NSE measurements at 0.05 Å(-1)Li(+) predicted by MD simulation. Our results suggest that the characteristic live times of the ions within the oxygen cages are mainly determined by the α relaxation that corresponds to local segmental motions of polymers, to a much lesser extent by the main chain relaxation, and not at all by the β relaxation or other faster processes. It is the first time decisive experimental evidence for a microscopic picture of the Li ion transportation process is shown in which the PEO chain forms EO cages over several monomer units and the Li ion "jump" from cage to cage. The role of the backbone of the polymer is discussed and contributes signifcantly to the Li ion transportation process. Moreover, detailed characteristic length and time scales of the Li(+) transport process in this polymer electrolyte are identified and interpreted.

  10. Pyrrolidinium-based ionic liquids doped with lithium salts: how does Li(+) coordination affect its diffusivity?

    PubMed

    Castiglione, Franca; Famulari, Antonino; Raos, Guido; Meille, Stefano V; Mele, Andrea; Appetecchi, Giovanni Battista; Passerini, Stefano

    2014-11-26

    We present the characterization of LiX-doped room-temperature ionic liquids (ILs) based on the N-butyl-N-methyl pyrrolidinium (PYR14) cation with two fluorinated anions: (trifluoromethanesulfonyl)-(nonafluorobutanesulfonyl)imide (X═IM14) and bis(pentafluoroethanesulfonyl)imide (X═BETI). The new data are also compared with previous results on PYR14TFSI (bis(trifluoromethanesulfonyl)imide). Their local organization has been investigated via NMR nuclear Overhauser effect (NOE) experiments for {(1)H-(19)F} and {(1)H-(7)Li} that give us details on PYR14(+)/X(-) and PYR14(+)/Li(+) contacts. We confirm the presence of [Li(X)2](-) coordinated species in all systems. The long-range, intermolecular NOEs have been detected and provide information on the ions' organization beyond the first solvation sphere. The ionic conductivity, viscosity and self-diffusion coefficients of the ionic mixtures have also been measured. The activation energies for the diffusion of the individual ions and for the fluidity are compared with those for the pure ILs. Finally, density functional calculations on [Li(BETI)2](-), [Li(IM14)2](-), and [Li(TFSI)2](-) complexes demonstrate that the minimum energy structures for all systems correspond to a tetrahedral coordination of the Li-ion by four oxygen atoms of the anions. Assuming very simple key steps for the Li(+) diffusion process (i.e., the concerted breaking and formation of Li-O bonds or the rearrangement around a tetrahedrally coordinated Li(+)), we calculate activation barriers that agree well with the experimental results (approximately 46 kJ/mol, in all systems).

  11. Electrochemical performance of V-doped spinel Li4Ti5O12/C composite anode in Li-half and Li4Ti5O12/LiFePO4-full cell

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Hu, Huai-Chou; Lin, S. J.; Chien, Wen-Chen

    2014-07-01

    This work reports the preparation of a V-doped Li4Ti5O12/C (donated as V-doped LTO/C) composite material, applying a solid-state method. Both metal doping and carbon coating are applied on the Li4Ti5O12 material, enhancing its rate capability and cycle stability. Furan polymer is used as a carbon source, and vanadium (V) is selected as a dopant. The properties of the materials are examined by X-ray diffraction (XRD), micro-Raman, scanning electron microscopy (SEM), high-resolution transmission microscopy (HR-TEM), the AC impedance method, and the galvanostatic charge/discharge method. For comparison, Li4Ti5O12/C composite materials with and without V doping are also examined. The Li4Ti4.90V0.10O12/C composite material achieves discharge capacities of 165.59 and 76.76 mAh g-1 at a 0.2/1C and 0.2/20C rate, respectively. A Li4Ti5O12/LiFePO4 full cell (LTO capacity-limited) is constructed and investigated. The full cell exhibits discharge capacities of 181, 178, 167, 142, 110, and 78 mAh g-1 at 0.2, 0.5, 1, 3, 5, and 10C, respectively. We determine that the Li4Ti4.95V0.05O12/C composite anode is an outstanding candidate for application in high-power Li-ion batteries.

  12. Compatibility of poly(bisAEA4)-LiTFSI-MPPipTFSI ionic liquid gel polymer electrolyte with Li4Ti5O12 lithium ion battery anode

    NASA Astrophysics Data System (ADS)

    Stepniak, Izabela

    2014-02-01

    This paper presents the use of Li4Ti5O12 (LTO) as anode with ionic liquid gel polymer electrolyte (IL-GPE) for application in lithium ion batteries. IL-GPE was obtained by in situ photopolymerization method of a mixture of ethoxylated bisphenol A diacrylate (bis(AEA4) and 0.4 M solution of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (MPPipTFSI). The surface morphology of the IL-GPE was studied using scanning electron microscopy (SEM). Stable, porous and flexible gel polymer electrolyte characterized high ionic conductivity (0.64 mS cm-1 at 25 °C) and a wide electrochemical stability window (ESW) (4.8 V). The performances of LTO/IL-GPE/Li cell were tested by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge. Good charge/discharge capacities and low capacity loss at medium C rates preliminary cycling was obtained.

  13. Nickel supported on nitrogen-doped carbon nanotubes as hydrogen oxidation reaction catalyst in alkaline electrolyte

    SciTech Connect

    Zhuang, Zhongbin; Giles, Stephen A.; Zheng, Jie; Jenness, Glen R.; Caratzoulas, Stavros; Vlachos, Dionisios G.; Yan, Yushan

    2016-01-14

    The development of a low-cost, high-performance platinum-group-metal-free hydroxide exchange membrane fuel cell is hindered by the lack of a hydrogen oxidation reaction catalyst at the anode. Here we report that a composite catalyst, nickel nanoparticles supported on nitrogen-doped carbon nanotubes, has hydrogen oxidation activity similar to platinum-group metals in alkaline electrolyte. Although nitrogen-doped carbon nanotubes are a very poor hydrogen oxidation catalyst, as a support, it increases the catalytic performance of nickel nanoparticles by a factor of 33 (mass activity) or 21 (exchange current density) relative to unsupported nickel nanoparticles. Density functional theory calculations indicate that the nitrogen-doped support stabilizes the nanoparticle against reconstruction, while nitrogen located at the edge of the nanoparticle tunes local adsorption sites by affecting the d-orbitals of nickel. Here, owing to its high activity and low cost, our catalyst shows significant potential for use in low-cost, high-performance fuel cells.

  14. Nickel supported on nitrogen-doped carbon nanotubes as hydrogen oxidation reaction catalyst in alkaline electrolyte

    DOE PAGES

    Zhuang, Zhongbin; Giles, Stephen A.; Zheng, Jie; ...

    2016-01-14

    The development of a low-cost, high-performance platinum-group-metal-free hydroxide exchange membrane fuel cell is hindered by the lack of a hydrogen oxidation reaction catalyst at the anode. Here we report that a composite catalyst, nickel nanoparticles supported on nitrogen-doped carbon nanotubes, has hydrogen oxidation activity similar to platinum-group metals in alkaline electrolyte. Although nitrogen-doped carbon nanotubes are a very poor hydrogen oxidation catalyst, as a support, it increases the catalytic performance of nickel nanoparticles by a factor of 33 (mass activity) or 21 (exchange current density) relative to unsupported nickel nanoparticles. Density functional theory calculations indicate that the nitrogen-doped support stabilizesmore » the nanoparticle against reconstruction, while nitrogen located at the edge of the nanoparticle tunes local adsorption sites by affecting the d-orbitals of nickel. Here, owing to its high activity and low cost, our catalyst shows significant potential for use in low-cost, high-performance fuel cells.« less

  15. Nickel supported on nitrogen-doped carbon nanotubes as hydrogen oxidation reaction catalyst in alkaline electrolyte.

    PubMed

    Zhuang, Zhongbin; Giles, Stephen A; Zheng, Jie; Jenness, Glen R; Caratzoulas, Stavros; Vlachos, Dionisios G; Yan, Yushan

    2016-01-14

    The development of a low-cost, high-performance platinum-group-metal-free hydroxide exchange membrane fuel cell is hindered by the lack of a hydrogen oxidation reaction catalyst at the anode. Here we report that a composite catalyst, nickel nanoparticles supported on nitrogen-doped carbon nanotubes, has hydrogen oxidation activity similar to platinum-group metals in alkaline electrolyte. Although nitrogen-doped carbon nanotubes are a very poor hydrogen oxidation catalyst, as a support, it increases the catalytic performance of nickel nanoparticles by a factor of 33 (mass activity) or 21 (exchange current density) relative to unsupported nickel nanoparticles. Density functional theory calculations indicate that the nitrogen-doped support stabilizes the nanoparticle against reconstruction, while nitrogen located at the edge of the nanoparticle tunes local adsorption sites by affecting the d-orbitals of nickel. Owing to its high activity and low cost, our catalyst shows significant potential for use in low-cost, high-performance fuel cells.

  16. Nickel supported on nitrogen-doped carbon nanotubes as hydrogen oxidation reaction catalyst in alkaline electrolyte

    PubMed Central

    Zhuang, Zhongbin; Giles, Stephen A.; Zheng, Jie; Jenness, Glen R.; Caratzoulas, Stavros; Vlachos, Dionisios G.; Yan, Yushan

    2016-01-01

    The development of a low-cost, high-performance platinum-group-metal-free hydroxide exchange membrane fuel cell is hindered by the lack of a hydrogen oxidation reaction catalyst at the anode. Here we report that a composite catalyst, nickel nanoparticles supported on nitrogen-doped carbon nanotubes, has hydrogen oxidation activity similar to platinum-group metals in alkaline electrolyte. Although nitrogen-doped carbon nanotubes are a very poor hydrogen oxidation catalyst, as a support, it increases the catalytic performance of nickel nanoparticles by a factor of 33 (mass activity) or 21 (exchange current density) relative to unsupported nickel nanoparticles. Density functional theory calculations indicate that the nitrogen-doped support stabilizes the nanoparticle against reconstruction, while nitrogen located at the edge of the nanoparticle tunes local adsorption sites by affecting the d-orbitals of nickel. Owing to its high activity and low cost, our catalyst shows significant potential for use in low-cost, high-performance fuel cells. PMID:26762466

  17. Probing the degradation mechanisms in electrolyte solutions for Li-ion batteries by in situ transmission electron microscopy.

    PubMed

    Abellan, Patricia; Mehdi, B Layla; Parent, Lucas R; Gu, Meng; Park, Chiwoo; Xu, Wu; Zhang, Yaohui; Arslan, Ilke; Zhang, Ji-Guang; Wang, Chong-Min; Evans, James E; Browning, Nigel D

    2014-03-12

    Development of novel electrolytes with increased electrochemical stability is critical for the next generation battery technologies. In situ electrochemical fluid cells provide the ability to rapidly and directly characterize electrode/electrolyte interfacial reactions under conditions directly relevant to the operation of practical batteries. In this paper, we have studied the breakdown of a range of inorganic/salt complexes relevant to state-of-the-art Li-ion battery systems by in situ (scanning) transmission electron microscopy ((S)TEM). In these experiments, the electron beam itself caused the localized electrochemical reaction that allowed us to observe electrolyte breakdown in real-time. The results of the in situ (S)TEM experiments matches with previous stability tests performed during battery operation and the breakdown products and mechanisms are also consistent with known mechanisms. This analysis indicates that in situ liquid stage (S)TEM observations could be used to directly test new electrolyte designs and identify a smaller library of candidate solutions deserving of more detailed characterization. A systematic study of electrolyte degradation is also a necessary first step for any future controlled in operando liquid (S)TEM experiments intent on visualizing working batteries at the nanoscale.

  18. Effect of Zn doping on the photoluminescence properties of LiNbO3 single crystals

    NASA Astrophysics Data System (ADS)

    Murillo, J. G.; Herrera, G.; Vega-Rios, A.; Flores-Gallardo, S.; Duarte-Moller, A.; Castillo-Torres, J.

    2016-12-01

    An extraordinary violet luminescence at 418 nm together with the intrinsic blue band at 440 nm with excitation in the UV region (380 nm) was observed in a series of LiNbO3 single crystals doped with Zn. Structural and photoluminescence properties were studied by Raman, UV reflectance, and fluorospectrometry, respectively. The emission peaks in PL spectra varied in amplitude according to the level of concentration of Zn in LiNbO3 crystals. It was found, from Raman spectroscopy studies, a connection between the appearance of the new emission band centered at 418 nm and a diminishing in the Li concentration in crystals, which suggest the displacement of the Li ions from their regular sites by the Zn ions. The maximum peak intensity of each one of the three PL emission components found from a deconvolution process shows a linear dependence on the Zn concentration present in the crystals studied.

  19. Effect of Cu doping on room temperature ferromagnetic behavior of Mn doped LiNbO3 films

    NASA Astrophysics Data System (ADS)

    Bu, Dechong; Fu, Yuting; Sun, Ning; Li, Chunjing; Li, Yanghua; An, Yukai; Liu, Jiwen

    2016-11-01

    Cu and Mn co-doped LiNbO3 films were deposited on Si (111) substrates by rf-magnetron sputtering. XRD shows a randomly oriented polycrystalline R3C structure of LiNbO3 was formed in the films annealed at 1000 °C for 1 h in air. XPS and XAFS determine that Mn2+ substitutes on the Li site with a Li vacancy and Cu2+ substitutes on the Nb site with an oxygen vacancy in the LiNbO3 lattice. SQUID measurements indicate that all the films exhibit room temperature ferromagnetism, attributed to a strong d-d electron interaction between Mn and Nb and the bound magnetic polarons resulting from the oxygen vacancies. The saturated magnetization increases but the atom magnetic moment decreases with increasing Cu content in the films. The drop of the atom magnetic moment may arise from the antiferromagnetic coupling among adjacent Cu ions and an antiparallel configuration between Cu2+ ions and their trapped electrons.

  20. Transition from half metal to semiconductor in Li doped g-C{sub 4}N{sub 3}

    SciTech Connect

    Hashmi, Arqum; Hu, Tao; Hong, Jisang

    2014-03-28

    We have investigated the structural and magnetic properties of Li doped graphitic carbon nitride (g-C{sub 4}N{sub 3}) using the van der Waals density functional theory. A free standing g-C{sub 4}N{sub 3} was known to show a half metallic state with buckling geometry, but this feature completely disappears in the presence of Li doping. Besides this structural modification, very interestingly, we have obtained that the Li doped g-C{sub 4}N{sub 3} shows dramatic change in its electronic structure. Both ferromagnetic and nonmagnetic states are almost degenerated in one Li atom doped system. However, the transition from half metallic state to semiconductor is observed with further increase of Li concentration and the calculated energy gap is 1.97 eV. We found that Li impurity plays as a donor element and charge transfer from the Li atom to neighboring N atoms induces a band gap. Overall, we have observed that the electronic and magnetic properties of g-C{sub 4}N{sub 3} are substantially modified by Li doping.

  1. Structural and spectroscopic properties of pure and doped LiCe(PO{sub 3}){sub 4}

    SciTech Connect

    Abdelhedi, M.; Horchani-Naifer, K.; Dammak, M.; Ferid, M.

    2015-10-15

    Graphical abstract: Emission and excitation and spectra of Eu{sup 3+} doped LiCe(PO{sub 3}){sub 4} host lattice with 1, 2, 3 and 4 mol%. - Highlights: • Europium–doped LiCe(PO{sub 3}){sub 4} were prepared by flux method. • It was analyzed by infrared and Raman spectroscopy, and luminescence spectroscopy. • LiCe(PO{sub 3}){sub 4} doped with Eu{sup 3+} ions as luminophore host materials to produce an intense red. - Abstract: Single crystals of LiCe(PO{sub 3}){sub 4} polyphosphate have been synthesized by the flux method and its structural and luminescence properties have been investigated. This compound crystallizes in the space group C2/c with unit cell dimensions a = 16.52(7) Å, b = 7.09(4) Å, c = 9.83 (4)Å, β = 126.29(4)°, Z = 8 and V = 927.84(3) Å{sup 3}. The obtained polytetraphosphate exhibits very small crystals and the dopant Eu{sup 3+} ions were successfully incorporated into the sites of Ce{sup 3+} ions of the host lattice. The spectroscopy properties confirm the potentiality of present LiCe(PO{sub 3}){sub 4} doped with Eu{sup 3+} ions as luminophore host materials to produce an intense red luminescence at 628 nm corresponding to {sup 5}D{sub 0} → {sup 7}F{sub 2} emission level and have significant importance in the development of emission optical systems.

  2. Natural abundance 17O, 6Li NMR and molecular modeling studies of the solvation structures of lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane liquid electrolytes

    NASA Astrophysics Data System (ADS)

    Wan, Chuan; Hu, Mary Y.; Borodin, Oleg; Qian, Jiangfeng; Qin, Zhaohai; Zhang, Ji-Guang; Hu, Jian Zhi

    2016-03-01

    Natural abundance 17O and 6Li NMR experiments, quantum chemistry and molecular dynamics studies were employed to investigate the solvation structures of Li+ at various concentrations of LiFSI in DME electrolytes. It was found that the chemical shifts of both 17O and 6Li changed with the concentration of LiFSI, indicating the changes of solvation structures with concentration. For the quantum chemistry calculations, the coordinated cluster LiFSI(DME)2 forms at first, and its relative ratio increases with increasing LiFSI concentration to 1 M. Then the solvation structure LiFSI(DME) become the dominant component. As a result, the coordination of forming contact ion pairs between Li+ and FSI- ion increases, but the association between Li+ and DME molecule decreases. Furthermore, at LiFSI concentration of 4 M the solvation structures associated with Li+(FSI-)2(DME), Li+2(FSI-)(DME)4 and (LiFSI)2(DME)3 become the dominant components. For the molecular dynamics simulation, with increasing concentration, the association between DME and Li+ decreases, and the coordinated number of FSI- increases, which is in perfect accord with the DFT results.

  3. Correlating Microstructural Lithium Metal Growth with Electrolyte Salt Depletion in Lithium Batteries Using ⁷Li MRI.

    PubMed

    Chang, Hee Jung; Ilott, Andrew J; Trease, Nicole M; Mohammadi, Mohaddese; Jerschow, Alexej; Grey, Clare P

    2015-12-09

    Lithium dendrite growth in lithium ion and lithium rechargeable batteries is associated with severe safety concerns. To overcome these problems, a fundamental understanding of the growth mechanism of dendrites under working conditions is needed. In this work, in situ (7)Li magnetic resonance (MRI) is performed on both the electrolyte and lithium metal electrodes in symmetric lithium cells, allowing the behavior of the electrolyte concentration gradient to be studied and correlated with the type and rate of microstructure growth on the Li metal electrode. For this purpose, chemical shift (CS) imaging of the metal electrodes is a particularly sensitive diagnostic method, enabling a clear distinction to be made between different types of microstructural growth occurring at the electrode surface and the eventual dendrite growth between the electrodes. The CS imaging shows that mossy types of microstructure grow close to the surface of the anode from the beginning of charge in every cell studied, while dendritic growth is triggered much later. Simple metrics have been developed to interpret the MRI data sets and to compare results from a series of cells charged at different current densities. The results show that at high charge rates, there is a strong correlation between the onset time of dendrite growth and the local depletion of the electrolyte at the surface of the electrode observed both experimentally and predicted theoretical (via the Sand's time model). A separate mechanism of dendrite growth is observed at low currents, which is not governed by salt depletion in the bulk liquid electrolyte. The MRI approach presented here allows the rate and nature of a process that occurs in the solid electrode to be correlated with the concentrations of components in the electrolyte.

  4. In Situ Generation of Poly (Vinylene Carbonate) Based Solid Electrolyte with Interfacial Stability for LiCoO2 Lithium Batteries

    PubMed Central

    Chai, Jingchao; Ma, Jun; Wang, Jia; Liu, Xiaochen; Liu, Haisheng; Zhang, Jianjun; Chen, Liquan

    2016-01-01

    Nowadays it is extremely urgent to seek high performance solid polymer electrolyte that possesses both interfacial stability toward lithium/graphitic anodes and high voltage cathodes for high energy density solid state batteries. Inspired by the positive interfacial effect of vinylene carbonate additive on solid electrolyte interface, a novel poly (vinylene carbonate) based solid polymer electrolyte is presented via a facile in situ polymerization process in this paper. It is manifested that poly (vinylene carbonate) based solid polymer electrolyte possess a superior electrochemical stability window up to 4.5 V versus Li/Li+ and considerable ionic conductivity of 9.82 × 10−5 S cm−1 at 50 °C. Moreover, it is demonstrated that high voltage LiCoO2/Li batteries using this solid polymer electrolyte display stable charge/discharge profiles, considerable rate capability, excellent cycling performance, and decent safety characteristic. It is believed that poly (vinylene carbonate) based electrolyte can be a very promising solid polymer electrolyte candidate for high energy density lithium batteries. PMID:28251055

  5. In Situ Generation of Poly (Vinylene Carbonate) Based Solid Electrolyte with Interfacial Stability for LiCoO2 Lithium Batteries.

    PubMed

    Chai, Jingchao; Liu, Zhihong; Ma, Jun; Wang, Jia; Liu, Xiaochen; Liu, Haisheng; Zhang, Jianjun; Cui, Guanglei; Chen, Liquan

    2017-02-01

    Nowadays it is extremely urgent to seek high performance solid polymer electrolyte that possesses both interfacial stability toward lithium/graphitic anodes and high voltage cathodes for high energy density solid state batteries. Inspired by the positive interfacial effect of vinylene carbonate additive on solid electrolyte interface, a novel poly (vinylene carbonate) based solid polymer electrolyte is presented via a facile in situ polymerization process in this paper. It is manifested that poly (vinylene carbonate) based solid polymer electrolyte possess a superior electrochemical stability window up to 4.5 V versus Li/Li(+) and considerable ionic conductivity of 9.82 × 10(-5) S cm(-1) at 50 °C. Moreover, it is demonstrated that high voltage LiCoO2/Li batteries using this solid polymer electrolyte display stable charge/discharge profiles, considerable rate capability, excellent cycling performance, and decent safety characteristic. It is believed that poly (vinylene carbonate) based electrolyte can be a very promising solid polymer electrolyte candidate for high energy density lithium batteries.

  6. Glass transition temperature and conductivity in Li2O and Na2O doped borophosphate glasses

    NASA Astrophysics Data System (ADS)

    Ashwajeet, J. S.; Sankarappa, T.; Ramanna, R.; Sujatha, T.; Awasthi, A. M.

    2015-08-01

    Two alkali doped Borophosphate glasses in the composition, (B2O3)0.2. (P2O5)0.3. (Na2O)(0.5-x). (Li2O)x, where x = 0.05 to 0.50 were prepared by standard melt quenching method at 1200K. Non-crystalline nature was confirmed by XRD studies. Room temperature density was measured by Archimedes principle. DC conductivity in the temperature range from 300K to 575K has been measured. Samples were DSC studied in the temperature range from 423K to 673K and glass transition temperature was determined. Glass transition temperature passed through minima for Li2O con.2centration between 0.25 and 0.30 mole fractions. Activation energy of conduction has been determined by analyzing temperature variation of conductivity determining Arrhenius law. Conductivity passed through minimum and activation passed through maximum for Li2O content from 0.25 to 0.30 mole fractions. Glass transition temperature passed through minimum for the same range of Li2O content. These results revealed mixed alkali effect taking place in these glasses. It is for the first time borophosphate glasses doped with Li2O and Na2O have been studied for density and dc conductivity and, the mixed alkali effect (MAE) has been observed.

  7. Damage profile examination on ion irradiated PEEK by 6Li doping and neutron depth profiling technique

    NASA Astrophysics Data System (ADS)

    Vacík, J.; Červená, J.; Hnatowicz, V.; Švorčík, V.; Kobayashi, Y.; Fink, D.; Klett, R.

    1998-05-01

    Depth structure of radiation damaged surface layer of poly(aryl-ether-ether ketone) (PEEK) a polymer was studied using doping with 6Li atoms combined with nondestructive neutron depth profiling (NDP) method. The PEEK foils were irradiated with 2 MeV O + ions up to a fluence of 6 × 10 14 ions/cm 2. The damage profiles in the samples were visualized by doping of the samples with 5 M LiCl water solution at room temperature (RT) for 22.5 h. The Li ions are trapped on ion-produced radiation defects and the Li depth profiles are determined by the NDP method. NDP experiments were performed before and after leaching of excess of lithium atoms from the samples in distilled water at RT for 2 h. The leaching leads to dramatic changes in the Li depth distribution which, at low ion fluences, is similar in shape to the electronic energy loss profile of 2 MeV O + ions. For the higher fluences double-peaked profile occurs, which indicates a competition between different degradation processes in ion irradiated polymer.

  8. Electrochemical Windows of Sulfone-Based Electrolytes for High-Voltage Li-Ion Batteries

    SciTech Connect

    Shao, Nan; Sun, Xiao-Guang; Dai, Sheng; Jiang, Deen

    2011-01-01

    Further development of high-voltage lithium-ion batteries requires electrolytes with electrochemical windows greater than 5 V. Sulfone-based electrolytes are promising for such a purpose. Here we compute the electrochemical windows for experimentally tested sulfone electrolytes by different levels of theory in combination with various solvation models. The MP2 method combined with the polarizable continuum model is shown to be the most accurate method to predict oxidation potentials of sulfone-based electrolytes with mean deviation less than 0.29 V. Mulliken charge analysis shows that the oxidation happens on the sulfone group for ethylmethyl sulfone and tetramethylene sulfone, and on the ether group for ether functionalized sulfones. Large electrochemical windows of sulfone-based electrolytes are mainly contributed by the sulfone group in the molecules which helps lower the HOMO level. This study can help understand the voltage limits imposed by the sulfone-based electrolytes and aid in designing new electrolytes with greater electrochemical windows.

  9. Electrochemical windows of sulfone-based electrolytes for high-voltage Li-ion batteries.

    PubMed

    Shao, Nan; Sun, Xiao-Guang; Dai, Sheng; Jiang, De-en

    2011-10-27

    Further development of high-voltage lithium-ion batteries requires electrolytes with electrochemical windows greater than 5 V. Sulfone-based electrolytes are promising for such a purpose. Here we compute the electrochemical windows for experimentally tested sulfone electrolytes by different levels of theory in combination with various solvation models. The MP2 method combined with the polarizable continuum model is shown to be the most accurate method to predict oxidation potentials of sulfone-based electrolytes with mean deviation less than 0.29 V. Mulliken charge analysis shows that the oxidation happens on the sulfone group for ethylmethyl sulfone and tetramethylene sulfone, and on the ether group for ether functionalized sulfones. Large electrochemical windows of sulfone-based electrolytes are mainly contributed by the sulfone group in the molecules which helps lower the HOMO level. This study can help understand the voltage limits imposed by the sulfone-based electrolytes and aid in designing new electrolytes with greater electrochemical windows.

  10. Improved Li storage performance in SnO2 nanocrystals by a synergetic doping

    SciTech Connect

    Wan, Ning; Lu, Xia; Wang, Yuesheng; Zhang, Weifeng; Bai, Ying; Hu, Yong -Sheng; Dai, Sheng

    2016-01-06

    Tin dioxide (SnO2) is a widely investigated lithium (Li) storage material because of its easy preparation, two-step storage mechanism and high specific capacity for lithium-ion batteries (LIBs). In this contribution, a phase-pure cobalt-doped SnO2 (Co/SnO2) and a cobalt and nitrogen co-doped SnO2 (Co-N/SnO2) nanocrystals are prepared to explore their Li storage behaviors. It is found that the morphology, specific surface area, and electrochemical properties could be largely modulated in the doped and co-doped SnO2 nanocrystals. Gavalnostatic cycling results indicate that the Co-N/SnO2 electrode delivers a specific capacity as high as 716 mAh g–1 after 50 cycles, and the same outstanding rate performance can be observed in subsequent cycles due to the ionic/electronic conductivity enhancement by co-doping effect. Further, microstructure observation indicates the existence of intermediate phase of Li3N with high ionic conductivity upon cycling, which probably accounts for the improvements of Co-N/SnO2 electrodes. Furthermore, we find that the method of synergetic doping into SnO2 with Co and N, with which the electrochemical performances is enhanced remarkably, undoubtedly, will have an important influence on the material itself and community of LIBs as well.

  11. Confined Solid Electrolyte Interphase Growth Space with Solid Polymer Electrolyte in Hollow Structured Silicon Anode for Li-Ion Batteries.

    PubMed

    Ma, Tianyi; Yu, Xiangnan; Cheng, Xiaolu; Li, Huiyu; Zhu, Wentao; Qiu, Xinping

    2017-04-07

    Silicon anodes for lithium-ion batteries are of much interest owing to their extremely high specific capacity but still face some challenges, especially the tremendous volume change which occurs in cycling and further leads to the disintegration of electrode structure and excessive growth of solid electrolyte interphase (SEI). Here, we designed a novel approach to confine the inward growth of SEI by filling solid polymer electrolyte (SPE) into pores of hollow silicon spheres. The as-prepared composite delivers a high specific capacity of more than 2100 mAh g(-1) and a long-term cycle stability with a reversible capacity of 1350 mAh g(-1) over 500 cycles. The growing behavior of SEI was investigated by electrochemical impedance spectroscopy and differential scanning calorimetry, and the results revealed that SPE occupies the major space of SEI growth and thus confines its excessive growth, which significantly improves cycle performance and Coulombic efficiency of cells embracing hollow silicon spheres.

  12. Ab initio calculations of the electronic structure of silicon nanocrystals doped with shallow donors (Li, P)

    SciTech Connect

    Kurova, N. V. Burdov, V. A.

    2013-12-15

    The results of ab initio calculations of the electronic structure of Si nanocrystals doped with shallow donors (Li, P) are reported. It is shown that phosphorus introduces much more significant distortions into the electronic structure of the nanocrystal than lithium, which is due to the stronger central cell potential of the phosphorus ion. It is found that the Li-induced splitting of the ground state in the conduction band of the nanocrystal into the singlet, doublet, and triplet retains its inverse structure typical for bulk silicon.

  13. The correlation of the properties of pyrrolidinium-based ionic liquid electrolytes with the discharge-charge performances of rechargeable Li-O2 batteries

    NASA Astrophysics Data System (ADS)

    Li, Yu; Zhang, Zhonglin; Duan, Donghong; Sun, Yanbo; Wei, Guoqiang; Hao, Xiaogang; Liu, Shibin; Han, Yunxia; Meng, Weijuan

    2016-10-01

    Pyrrolidinium-based ionic liquids (ILs), such as PYR13TFSI, PYR14TFSI, and PYR1(2O1)TFSI, exhibit high thermal and electrochemical stability with wide electrochemical windows as electrolytes for application to rechargeable Li-O2 batteries. In this work, several fundamental properties of three ILs are measured: the ionic conductivity, oxygen solubility, and oxygen diffusion coefficient. The oxygen electro-reduction kinetics is characterized using cyclic voltammetry. The performances of Li-O2 batteries with these IL electrolytes are also investigated using electrochemical impedance spectroscopy and galvanostatic discharge-charge tests. The results demonstrate that the PYR1(2O1)TFSI electrolyte battery has a higher first-discharge voltage than the PYR13TFSI electrolyte and PYR14TFSI electrolyte batteries. Both PYR13TFSI- and PYR1(2O1)TFSI-based batteries exhibit higher first-discharge capacities and better cycling stabilities than the PYR14TFSI-based battery for 30 cycles. A theoretical analysis of the experimental results shows that the diffusion coefficient and solubility of oxygen in the electrolyte remarkably affect the discharge capacity and cycling stability of the batteries. Particularly, the oxygen diffusion coefficient of the IL electrolyte can effectively facilitate the electrochemical oxygen electro-reduction reaction and oxygen concentration distribution in the catalyst layers of air electrodes. The oxygen diffusion coefficient and oxygen solubility improvements of IL electrolytes can enhance the discharge-charge performances of Li-O2 batteries.

  14. Co-existence of LiI and KI in filler-free, quasi-solid-state electrolyte for efficient and stable dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Agarwala, S.; Thummalakunta, L. N. S. A.; Cook, C. A.; Peh, C. K. N.; Wong, A. S. W.; Ke, L.; Ho, G. W.

    A quasi-solid-state electrolyte employing a poly (ethylene oxide)/LiI system without a filler is evaluated. The electrolyte is optimized for various potassium iodide (KI) concentrations. The electrolyte containing 14.5 wt.% KI exhibits the highest conductivity (3.0 × 10 -3 S cm -1). An efficiency of 4.5% is achieved using this composition of the electrolyte. It is shown that the introduction of KI in a conventional PEO/I 2/LiI electrolyte system prevents the crystallization of the polymer matrix and enhances the ionic conductivity. The energy conversion efficiency of the device is further enhanced to 5.8% by incorporating a light-scattering layer.

  15. Solid-State Li-Ion Batteries Using Fast, Stable, Glassy Nanocomposite Electrolytes for Good Safety and Long Cycle-Life.

    PubMed

    Tan, Guoqiang; Wu, Feng; Zhan, Chun; Wang, Jing; Mu, Daobin; Lu, Jun; Amine, Khalil

    2016-03-09

    The development of safe, stable, and long-life Li-ion batteries is being intensively pursued to enable the electrification of transportation and intelligent grid applications. Here, we report a new solid-state Li-ion battery technology, using a solid nanocomposite electrolyte composed of porous silica matrices with in situ immobilizing Li(+)-conducting ionic liquid, anode material of MCMB, and cathode material of LiCoO2, LiNi1/3Co1/3Mn1/3O2, or LiFePO4. An injection printing method is used for the electrode/electrolyte preparation. Solid nanocomposite electrolytes exhibit superior performance to the conventional organic electrolytes with regard to safety and cycle-life. They also have a transparent glassy structure with high ionic conductivity and good mechanical strength. Solid-state full cells tested with the various cathodes exhibited high specific capacities, long cycling stability, and excellent high temperature performance. This solid-state battery technology will provide new avenues for the rational engineering of advanced Li-ion batteries and other electrochemical devices.

  16. Solid-State Li-Ion Batteries Using Fast, Stable, Glassy Nanocomposite Electrolytes for Good Safety and Long Cycle-Life

    SciTech Connect

    Tan, Guoqiang; Wu, Feng; Zhan, Chun; Wang, Jing; Mu, Daobin; Lu, Jun; Amine, Khalil

    2016-03-09

    The development of safe, stable, and long-life Li-ion batteries is being intensively pursued to enable the electrification of transportation and intelligent grid applications. Here, we report a new solid-state Li-ion battery technology, using a solid nanocomposite electrolyte composed of porous silica matrices with in situ immobilizing Li+ conducting ionic liquid, anode material of MCMB, and cathode material of LiCoO2, LiNi1/3Co1/3Mn1/3O2, or LiFePO4. An injection printing method is used for the electrode/electrolyte preparation. Solid nanocomposite electrolytes exhibit superior performance to the conventional organic electrolytes with regard to safety and cycle-life. They also have a transparent glassy structure with high ionic conductivity and good mechanical strength. Solid-state full cells tested with the various cathodes exhibited high specific capacities, long cycling stability, and excellent high temperature performance. This solid-state battery technology will provide new avenues for the rational engineering of advanced Li-ion batteries and other electrochemical devices.

  17. The Effects of Lithium Triflate (LiCF3SO3) on the PMMA-based Solid Polymer Electrolytes

    NASA Astrophysics Data System (ADS)

    Chew, K. W.; Chen, S. S.; Pang, W. L.; Tan, C. G.; Osman, Z.

    2010-03-01

    The effects of Lithium triflate salt (LiCF3SO3), on the poly (methyl methacrylate) (PMMA)-based solid polymer electrolytes plasticized with propylene carbonate (PC) solvated in Tetrahydrofuran (THF) have been studied through a.c impedance spectroscopy and infrared spectroscopy. Lithium triflate was incorporated into the predetermined PMMA/PC system that has the highest value of ionic conductivity. In current investigations, four combination systems: Pure PMMA, (PMMA+PC) systems, (PMMA+LiCF3SO3) and (PMMA+PC+LiCF3SO3) systems were prepared using the solution cast method. Solutions were stirred for numerous hours to obtain a homogenous solution before it is poured into the petri dishes under ambient temperature to form the solid electrolyte thin film. The films were then removed from petri discs and transferred into the dessicator for further drying prior to the different tests. From the characterization done through the a.c impedance spectroscopy, the highest room temperature ionic conductivity in the pure PMMA sample, (PMMA+PC) system and (PMMA+LiCF3SO3) system is 2.83×10-12 Scm-1, 4.39×10-11 Scm-1 and 3.93×10-6 Scm-1 respectively. The conductivity for (PMMA+PC+LiCF3SO3) system was obtained with the 30 wt% of lithium triflate, which is 2.48×10-5 Scm-1. Infrared spectroscopy shows that complexation occurred between the polymer and the plasticizer, and the polymer and plasticizer and salt. The interactions have been studied in the C=O band, C-O-C band and the O-CH3 band.

  18. Characterization of pore and crystal structure of synthesized LiBOB with varying quality of raw materials as electrolyte for lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Lestariningsih, Titik; Ratri, Christin Rina; Wigayati, Etty Marty; Sabrina, Qolby

    2016-02-01

    Characterization of pore structure and crystal structure of the LiB(C2O4)2H2O or LIBOB compound has been performed in this study. These recent years, research regarding LiBOB electrolyte salt have been performed using analytical-grade raw materials, therefore this research was aimed to synthesized LiBOB electrolyte salt using the cheaper and abundant technical-grade raw materials. Lithium hydroxide (LiOH), oxalic acid dihydrate (H2C2O4.2H2O), and boric acid (H3BO3) both in technical-grade and analytical-grade quality were used as raw materials for the synthesis of LiBOB. Crystal structure characterization results of synthesized LiBOB from both technical-grade and analytical-grade raw materials have shown the existence of LiBOB and LiBOB hydrate phase with orthorombic structure. These results were also confirmed by FT-IR analysis, which showed the functional groups of LiBOB compounds. SEM analysis results showed that synthesized LiBOB has spherical structure, while commercial LiBOB has cylindrical structure. Synthesized LiBOB has a similar pore size of commercial LiBOB, i.e. 19 nm (mesoporous material). Surface area of synthesized LiBOB from analytical-grade raw materials and technical-grade materials as well as commercial LIBOB were 88.556 m2/g, 41.524 m2/g, and 108.776 m2/g, respectively. EIS analysis results showed that synthesized LiBOB from technical-grade raw materials has lower conductivity than synthesized LiBOB from analytical-grade raw materials.

  19. Garnet-Type Fast Li-Ion Conductors with High Ionic Conductivities for All-Solid-State Batteries.

    PubMed

    Wu, Jian-Fang; Pang, Wei Kong; Peterson, Vanessa K; Wei, Lu; Guo, Xin

    2017-04-12

    All-solid-state Li-ion batteries with metallic Li anodes and solid electrolytes could offer superior energy density and safety over conventional Li-ion batteries. However, compared with organic liquid electrolytes, the low conductivity of solid electrolytes and large electrolyte/electrode interfacial resistance impede their practical application. Garnet-type Li-ion conducting oxides are among the most promising electrolytes for all-solid-state Li-ion batteries. In this work, the large-radius Rb is doped at the La site of cubic Li6.10Ga0.30La3Zr2O12 to enhance the Li-ion conductivity for the first time. The Li6.20Ga0.30La2.95Rb0.05Zr2O12 electrolyte exhibits a Li-ion conductivity of 1.62 mS cm(-1) at room temperature, which is the highest conductivity reported until now. All-solid-state Li-ion batteries are constructed from the electrolyte, metallic Li anode, and LiFePO4 active cathode. The addition of Li(CF3SO2)2N electrolytic salt in the cathode effectively reduces the interfacial resistance, allowing for a high initial discharge capacity of 152 mAh g(-1) and good cycling stability with 110 mAh g(-1) retained after 20 cycles at a charge/discharge rate of 0.05 C at 60 °C.

  20. 7Li NMR spectroscopy and ion conduction mechanism in mesoporous silica (SBA-15) composite poly(ethylene oxide) electrolyte

    NASA Astrophysics Data System (ADS)

    Reddy, M. Jaipal; Chu, Peter P.

    A composite of mesoporous silica (SBA-15) with a polyethylene oxide (PEO) polymer electrolyte is examined for use in various electrochemical devices. Incorporation of SBA-15 in a PEO:LiClO 4 polymer electrolyte facilitates salt dissociation, enhances ion conductivity, and improves miscibility between organic and inorganic moieties. Optimized conductivity is found at 10 wt.% SBA-15 composition, above this concentration the conductivity is reduced due to aggregation of a SBA-15:Li rich phase. Heating above melt temperature of PEO allows more of the polymer segments to interact with SBA-15. This results in a greater degree of disorder upon cooling, and the ion conductivity is enhanced. A 7Li MAS NMR study reveals three types of lithium-ion coordination. Two major types of conduction mechanism can be identified: one through conventional amorphous PEO; a second via hopping in a sequential manner by replacing the nearby vacancies ('holes') on the surface (both interior and exterior) of the SBA-15 channels.

  1. Synthesis of yttria-doped bismuth oxide powder by carbonate coprecipitation for IT-SOFC electrolyte.

    PubMed

    Lee, J G; Kim, S H; Yoon, H H

    2011-01-01

    Yttria-doped bismuth oxide (YBO) powders were synthesized by ammonium carbonate coprecipitation for the preparation of electrolytes of an intermediate temperature solid oxide fuel cell (IT-SOFC). The starting salts were yttrium and bismuth nitrate. The crystal structures and the morphological characteristics of the particles were analyzed by XRD and SEM, respectively. The ionic conductivity of the sintered pellet was measured by an electrochemical impedance analyzer. The size of the calcined YBO powders were in the range of 20-100 nm as measured by SEM images. The YBO pellets had a face-centered cubic structure, and their crystallite size was about 54-88 nm. The ionic conductivity of the YBO pellets sintered at 800 degrees C was observed to be 2.7 x 10(-1) Scm-(-1) at 700 degrees C. The ball-milling of the YBO powder before it was pelletized was found to have been unrequired probably because of a good sinterability of the YBO powders that was prepared via the ammonium carbonate coprecipitation method. The results showed that the ammonium carbonate coprecipitation process could be used as the cost-efficient method of producing YBO electrolytes for IT-SOFC.

  2. Pulse-Shape Analysis of Neutron-Induced Scintillation Light in Ni-doped 6LiF/ZnS

    SciTech Connect

    Cowles, Christian C.; Behling, Richard S.; Imel, G. R.; Kouzes, Richard T.; Lintereur, Azaree; Robinson, Sean M.; Stave, Sean C.; Siciliano, Edward R.; Wang, Zheming

    2016-10-06

    Abstract–Alternatives to 3He are being investigated for gamma-ray insensitive neutron detection applications, including plutonium assay. One promising material is lithium-6 fluoride with silver activated zinc sulfide 6LiF/ZnS(Ag) in conjunction with a wavelength shifting plastic. Doping the 6LiF/ZnS(Ag) with nickel (Ni) has been proposed as a means of reducing the decay time of neutron signal pulses. This research performed a pulse shape comparison between Ni-doped and non-doped 6LiF/ZnS(Ag) neutron pulses. The Ni-doped 6LiF/ZnS(Ag) had a 32.7% ± 0.3 increase in neutron pulse height and a 32.4% ± 0.3 decrease in neutron pulse time compared to the non-doped 6LiF/ZnS(Ag). Doping 6LiF/ZnS(Ag) with nickel may allow neutron detector operation with improved signal to noise ratios, and reduced pulse pileup affects, increasing the accuracy and range of source activities with which such a detector could operate.

  3. DFT STUDY OF HYDROGEN STORAGE ON Li- AND Na-DOPED C59B HETEROFULLERENE

    NASA Astrophysics Data System (ADS)

    Zahedi, Ehsan; Mozaffari, Majid

    2014-05-01

    Effect of light alkali metal (Li and Na) decorated on the C59B heterofullerene for hydrogen storage is considered using DFT-MPW1PW91 method. Results show that Li and Na atoms strongly prefer to adsorb on top of five-member and six-member ring where a carbon atom is replaced by a boron atom. Significant charge transfer from the alkali metal to the C59B compensates for the electron deficiency of C59B and makes the latter aromatic in nature. Corrected binding energies of hydrogen molecule on the alkali-doped C59B using counterpoise method, structural properties and NBO analysis indicate that first hydrogen molecule is adsorbed physically and does not support minimal conditions of DOE requirement. Finally, positive values of binding energies for the adsorption of a second hydrogen molecule show that alkali doped C59B are capable of storing a maximum of one hydrogen molecule.

  4. Laser cooling of Yb³⁺-doped LuLiF₄ crystal.

    PubMed

    Zhong, Biao; Yin, Jigang; Jia, Youhua; Chen, Lin; Hang, Yin; Yin, Jianping

    2014-05-01

    In order to meet the demands for applications of optical refrigerators in the fields of spaceflight, aviation, space science, and detection, a 2 wt. % Yb3+-doped LuLiF4 crystal, as a new laser cooling material, was prepared and demonstrated by using a 178 mW diode laser centered at 1015 nm and a resonant extra-cavity scheme with an enhancement factor of 12.8. Cooling efficiency of 1.27% and a temperature drop of 14.3 K/W are obtained with 79% of the incident laser power being absorbed. Based on our results, a sample with background absorption of α=4.2×10(-4)  cm(-1) can be potentially cooled down to ∼145 K. Our investigation shows that Yb3+-doped LuLiF4 crystal is potentially a promising candidate for solid-state refrigeration.

  5. Crystal growth and optical properties of indium doped LiCaAlF6 scintillator single crystals

    NASA Astrophysics Data System (ADS)

    Tanaka, Chieko; Yokota, Yuui; Kurosawa, Shunsuke; Yamaji, Akihiro; Jary, Vitezslav; Babin, Vladimir; Pejchal, Jan; Ohashi, Yuji; Kamada, Kei; Nikl, Martin; Yoshikawa, Akira

    2017-03-01

    The In-doped LiCaAlF6 [In:LiCAF] single crystals were grown by the micro-pulling-down (μ-PD) method, and the phases, chemical compositions, transmittance and radioluminescence spectra were investigated. All the grown crystals showed high transparency and single phase of LiCAF without visible cracks and inclusions except for the end part of In2%:LiCAF crystal which included the impurity phase. In the radioluminescence spectra of the In:LiCAF crystals under X-ray irradiation, the emission peak around 750 nm was revealed.

  6. Crystallinity of Li-doped Gd2O3:Eu3+ thin-film phosphors grown on Si (100) substrate

    NASA Astrophysics Data System (ADS)

    Yi, Soung Soo; Bae, Jong Seong; Moon, Byung Kee; Jeong, Jung Hyun; Kim, Jung Hwan

    2005-02-01

    Gd2O3:Eu3+ and Li-doped Gd2O3:Eu3+ luminescent thin films have been grown on Si (100) substrates using pulsed-laser deposition. The films grown at different deposition conditions show different microstructural and luminescent characteristics. Both cubic and monoclinic crystalline structures were observed in both Gd2O3:Eu3+ and Li-doped Gd2O3:Eu3+ films, but the cubic phase becomes more dominant and the ratio of peak values IC(222)/IM(-402) increases rapidly for Li-doped Gd2O3:Eu3+ films. The photoluminescence brightness data obtained from Li-doped Gd2O3:Eu3+ films indicate that Si (100) is a promising substrate for growth of high-quality Li-doped Gd2O3:Eu3+ thin-film red phosphor. In particular, the incorporation of Li + ions into the Gd2O3 lattice induced changes of crystallinity, surface roughness, and photoluminescence. The highest emission intensity was observed with Gd1.84Li0.08Eu0.08O3, whose brightness was a factor of 2.1 larger than that from Gd2O3:Eu3+ films. This phosphor is promising for applications in flat-panel displays.

  7. Improved Li(+) Storage through Homogeneous N-Doping within Highly Branched Tubular Graphitic Foam.

    PubMed

    Dong, Jinyang; Xue, Yanming; Zhang, Chao; Weng, Qunhong; Dai, Pengcheng; Yang, Yijun; Zhou, Min; Li, Cuiling; Cui, Qiuhong; Kang, Xiaohong; Tang, Chengchun; Bando, Yoshio; Golberg, Dmitri; Wang, Xi

    2017-02-01

    A novel carbon structure, highly branched homogeneous-N-doped graphitic (BNG) tubular foam, is designed via a novel N, N-dimethylformamide (DMF)-mediated chemical vapor deposition method. More structural defects are found at the branched portions as compared with the flat tube domains providing abundant active sites and spacious reservoirs for Li(+) storage. An individual BNG branch nanobattery is constructed and tested using in situ transmission electron microscopy and the lithiation process is directly visualized in real time.

  8. No-flash-point electrolytes applied to amorphous carbon/Li 1+ xMn 2O 4 cells for EV use

    NASA Astrophysics Data System (ADS)

    Arai, Juichi

    Use of no-flash-point electrolytes (NFEs) containing non-flammable solvent for an amorphous carbon/Li 1+ xMn 2O 4 cell has been studied. We prepared three NFEs: NFE1 was composed of 1 M (mol dm -3) of LiN[SO 2C 2F 5] 2 as supporting electrolyte, and 80 vol.% of methyl nonafluorobutyl ether (MFE) and 20 vol.% of ethyl methyl carbonate (EMC) as solvents; NFE2 was prepared by adding 0.5 M of EC (ethylene carbonate) to NFE1; and NFE3 was prepared by adding 0.1 M of LiPF 6 to NFE2. Charge-discharge performance of Li 1+ xMn 2O 4/Li cells and amorphous carbon/Li cells with NFEs were investigated. The amorphous carbon/Li 1+ xMn 2O 4 18650 cells were fabricated and investigated in terms of rate capability and cycle life. NFE2 showed good rate performance. NFE3 showed the best cycle life among the NFE electrolyte cells, though it had only fair rate performance. Electrochemical impedance spectroscopy (EIS), attenuated total reflection infrared (ATR-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were measured to study the effect of EC and LiPF 6.

  9. Microwave synthesis of molybdenum doped LiFePO4/C and its electrochemical studies.

    PubMed

    Naik, Amol; P, Sajan C

    2016-05-10

    A Mo-doped LiFePO4 composite was prepared successfully from an iron carbonyl complex by adopting a facile and rapid microwave assisted solid state method. The evolution of gases from the iron precursor produces a highly porous product. The formation and substitution of Mo in LiFePO4 were confirmed by X-ray diffraction; surface analysis was carried out by scanning electron microscopy, field emission scanning electron microscopy, and transmission electron microscopy. The electrochemical properties of the substituted LiFePO4 were examined by cyclic voltammetry, electrochemical impedance spectroscopy and by recording charge-discharge cycles. It was observed that the as prepared composites consisted of a single phase orthorhombic olivine-type structure, where Mo(6+) was successfully introduced into the M2(Fe) sites. Incorporation of supervalent Mo(6+) introduced Li(+) ion vacancies in LiFePO4. The synthesized material facilitated lithium ion diffusion during charging/discharging due to the charge compensation effect and porosity. The battery performance studies showed that LiMo0.05Fe0.095PO4 exhibited a maximum capacity of 169.7 mA h g(-1) at 0.1 C current density, with admirable stability retention. Even at higher current densities, the retention of the specific capacity was exceptional.

  10. Dual field effects in electrolyte-gated spinel ferrite: electrostatic carrier doping and redox reactions

    PubMed Central

    Ichimura, Takashi; Fujiwara, Kohei; Tanaka, Hidekazu

    2014-01-01

    Controlling the electronic properties of functional oxide materials via external electric fields has attracted increasing attention as a key technology for next-generation electronics. For transition-metal oxides with metallic carrier densities, the electric-field effect with ionic liquid electrolytes has been widely used because of the enormous carrier doping capabilities. The gate-induced redox reactions revealed by recent investigations have, however, highlighted the complex nature of the electric-field effect. Here, we use the gate-induced conductance modulation of spinel ZnxFe3−xO4 to demonstrate the dual contributions of volatile and non-volatile field effects arising from electronic carrier doping and redox reactions. These two contributions are found to change in opposite senses depending on the Zn content x; virtual electronic and chemical field effects are observed at appropriate Zn compositions. The tuning of field-effect characteristics via composition engineering should be extremely useful for fabricating high-performance oxide field-effect devices. PMID:25056718

  11. Towards P-Type Conductivity in SnO2 Nanocrystals through Li Doping

    SciTech Connect

    Chaparadza, Allen; Rananavare, Shankar B

    2010-01-22

    This paper examines electrical transport properties and Li doping in SnO2 synthesized by the sol–gel method. Solid-state 7Li-NMR lineshapes reveal that Li ions occupy two distinct sites with differing dynamic mobilities. The chemical exchange rate between the two sites is, however, too slow for detection on the NMR timescale. Compressed nanoparticulate films of this doped semiconductor exhibit a positive Seebeck coefficient implying a p-type conductivity. A variable-temperature direct current conductivity, over a 25–350 °C temperature range, follows an Efros–Shklovskii variable range hopping (ES-VRH) conduction mechanism (ln(ρ) versus T -1/2) at temperatures below 100 °C with a crossover to 2D Mott variable range hopping (M-VRH) (ln(ρ) versus T -1/3) conduction at temperatures above 250 °C. In a transition region between these two limiting behaviors, the dc resistivity exhibits an anomalous temperature-independent plateau. We suggest that its origin may lie in a carrier inversion phenomenon wherein the majority carriers switch from holes to electrons due to Li ion expulsion from the crystalline core and creation of oxygen vacancies generated by loss of oxygen at elevated temperatures.

  12. Investigations on the electrochemical decomposition of the electrolyte additive vinylene carbonate in Li metal half cells and lithium ion full cells

    NASA Astrophysics Data System (ADS)

    Qian, Yunxian; Schultz, Carola; Niehoff, Philip; Schwieters, Timo; Nowak, Sascha; Schappacher, Falko M.; Winter, Martin

    2016-11-01

    In this study, the decomposition of vinylene carbonate (VC) additive and its effect on the aging behavior is investigated in Li metal half cells and lithium ion full cells. Four electrolyte systems, the reference electrolyte with three VC additive amounts, i.e., 1, 5 and 10 vol% are examined with commercial LiNi1/3Mn1/3Co1/3O2 (NMC 111) cathode material and mesophase carbon microbeads (MCMB) anode material. The thickness changes of the cathode electrolyte interphase (CEI) and of the solid electrolyte interphase (SEI) after 5 constant current cycles at 0.1C and 200 constant current/constant voltage (potential) cycles at 1C are investigated for cells containing different amounts of VC. With the help of X-ray photoelectron spectroscopy (XPS) and high-performance liquid chromatography (HPLC), a correlation between CEI thickness change and electrolyte decomposition is figured out. The addition of VC leads to a thin CEI layer and a high capacity retention in a lithium metal half cell. A strong dependence of the performance on the VC concentration is found for half cells that results from the continuous consumption of electrolyte and the electrolyte additive at the Li metal counter electrode. In contrast, for full cells, even 1 vol% of VC helps to form both a stable CEI and SEI, while a larger amount of VC increases the CEI thickness, electric contact loss and the internal resistance.

  13. Density functional and molecular dynamics studies of solid electrolyte Li7La3Zr2O12

    NASA Astrophysics Data System (ADS)

    Johannes, Michelle; Hoang, Khang; Bernstein, Noam

    2012-02-01

    Garnet-type structured Li7La3Zr2O12(LLZO) is considered as a promising candidate for Li-ion battery solid electrolytes because of its high ionic conductivity and electrochemical and chemical stability. We use first-principles density-functional theory calculations and molecular dynamics simulations to reveal the underlying mechanism that drives a tetragonal to cubic transition at elevated temperatures, and also to explain why the cubic phase can be stabilized with the incorporation of a certain amount of impurities such as Al. We show that the relationship between the observance of a cubic phase and the measurement of a substantially higher ionic conductivity is a secondary effect not directly attributable to the presence of Al in the crystal structure. Suggestions for enhancing the ionic conductivity in LLZO will also be discussed.

  14. Thermoluminescence characterization of Ag-doped Li2 B4 O7 single crystal materials.

    PubMed

    Kuralı, D; Ekdal Karalı, E; Kelemen, A; Holovey, V; Can, N; Karalı, T

    2016-12-13

    In this study, the thermoluminescence (TL) characteristics of Ag-doped and undoped lithium tetraborate (Li2 B4 O7 , LTB) materials, grown using the Czochralski method, were reported. The TL properties of LTB:Ag, such as glow curve structure, dose response, fading and reproducibility, were investigated. The glow curve of the Li2 B4 O7 :Ag single crystal consists of four peaks located at approximately 75, 130, 190 and 275°C; in undoped LTB, the single crystal shows a broad glow curve with peaks at 65, 90, 125, 160 and 190°C using a heating rate of 5°C/s in the 50-350°C temperature region. The high temperature peak of Ag-doped sample at 275°C has a nonlinear dose response within the range from 33 mGy to 9 Gy. There is a linear response in the range of 33-800 mGy; after which, a sublinear region appears up to 9 Gy for Ag-doped LTB single crystal. For undoped single crystal, the dose response is supralinear for low doses and linear for the region between 1 and 9 Gy. The thermal fading ratio of the undoped material is almost 60% for the high temperature peak after 7 days. Ag-doped LTB single crystal exhibits different behaviour over a period of 7 days.

  15. Li2S encapsulated by nitrogen-doped carbon for lithium sulfur batteries

    SciTech Connect

    Chen, Lin; Liu, Yuzi; Ashuri, Maziar; Liu, Caihong; Shaw, Leon L.

    2014-09-26

    Using high-energy ball milling of the Li2S plus carbon black mixture followed by carbonization of pyrrole, we have established a facile approach to synthesize Li2S-plus-C composite particles of average size 400 nm, encapsulated by a nitrogen-doped carbon shell. Such an engineered core–shell structure exhibits an ultrahigh initial discharge specific capacity (1029 mAh/g), reaching 88% of the theoretical capacity (1,166 mAh/g of Li2S) and thus offering the highest utilization of Li2S in the cathode among all of the reported works for the encapsulated Li2S cathodes. This Li2S/C composite core with a nitrogen-doped carbon shell can still retain 652 mAh/g after prolonged 100 cycles. These superior properties are attributed to the nitrogen-doped carbon shell that can improve the conductivity to enhance the utilization of Li2S in the cathode. As a result, fine particle sizes and the presence of carbon black within the Li2S core may also play a role in high utilization of Li2S in the cathode.

  16. Evaluation of the physi- and chemisorption of hydrogen in alkali (Na, Li) doped fullerenes

    SciTech Connect

    Ward, Patrick A.; Teprovich, Jr., Jospeph A.; Compton, Robert N.; Schwartz, Viviane; Veith, Gabriel M.; Zidan, Ragiay

    2015-01-11

    Here, alkali doped fullerenes synthesized by two different solvent assisted mixing techniques are compared for their hydrogen uptake activity. In this study we investigated the interaction of hydrogen with alkali doped fullerenes via physisorption. In addition, we present the first mass spectrometric evidence for the formation of C60H60 via chemisorption. Hydrogen physisorption isotherms up to 1 atm at temperatures ranging from 77-303 K were measured demonstrating an increase in hydrogen uptake versus pure C60 and increased isosteric heats of adsorption for the lithium doped fullerene Li12C60. However, despite these improvements the low amount of physisorbed hydrogen at 1 atm and 77 K in these materials suggests that fullerenes do not possess enough accessible surface area to effectively store hydrogen due to their close packed crystalline nature.

  17. Crystal structure analysis and first principle investigation of F doping in LiFePO4

    NASA Astrophysics Data System (ADS)

    Milović, Miloš; Jugović, Dragana; Cvjetićanin, Nikola; Uskoković, Dragan; Milošević, Aleksandar S.; Popović, Zoran S.; Vukajlović, Filip R.

    2013-11-01

    This work presents the synthesis of F-doped LiFePO4/C composite by the specific modification of the recently suggested synthesis procedure based on an aqueous precipitation of precursor material in molten stearic acid, followed by a high temperature treatment. Besides the lattice parameters and the primitive cell volume reductions, compared to the undoped sample synthesized under the same conditions, the Rietveld refinement also shows that fluorine ions preferably occupy specific oxygen sites. Particularly, the best refinement is accomplished when fluorine ions occupy O(2) sites exclusively. By means of up-to-date electronic structure and total energy calculations this experimental finding is theoretically confirmed. Such fluorine doping also produces closing of the gap in the electronic structure and consequently better conductivity properties of the doped compound. In addition, the morphological and electrochemical performances of the synthesized powder are fully characterized.

  18. Evaluation of the physi- and chemisorption of hydrogen in alkali (Na, Li) doped fullerenes

    DOE PAGES

    Ward, Patrick A.; Teprovich, Jr., Jospeph A.; Compton, Robert N.; ...

    2015-01-11

    Here, alkali doped fullerenes synthesized by two different solvent assisted mixing techniques are compared for their hydrogen uptake activity. In this study we investigated the interaction of hydrogen with alkali doped fullerenes via physisorption. In addition, we present the first mass spectrometric evidence for the formation of C60H60 via chemisorption. Hydrogen physisorption isotherms up to 1 atm at temperatures ranging from 77-303 K were measured demonstrating an increase in hydrogen uptake versus pure C60 and increased isosteric heats of adsorption for the lithium doped fullerene Li12C60. However, despite these improvements the low amount of physisorbed hydrogen at 1 atm andmore » 77 K in these materials suggests that fullerenes do not possess enough accessible surface area to effectively store hydrogen due to their close packed crystalline nature.« less

  19. Computational modeling of the structure and the ionic conductivity of the solid electrolyte materials Li3AsS4 and its Ge substitutions

    NASA Astrophysics Data System (ADS)

    Al-Qawasmeh, Ahmad; Holzwarth, N. A. W.

    Oak Ridge National Laboratory (G. Sahu et al.) reported that the substitution of Ge into Li3AsS4 leads to the composition Li3.334Ge0.334As0.666S4 with impressively high ionic conductivity . We use ab initio calculations to examine the structural relationships and the ionic conductivity mechanisms for pure Li3AsS4, Li3.334Ge0.334As0.666S4, and other compositions of these electrolytes. Supported by NSF Grant DMR-1105485 and 1507942 and WFU's DEAC cluster.

  20. High performance silicon nanoparticle anode in fluoroethylene carbonate-based electrolyte for Li-ion batteries.

    PubMed

    Lin, Yong-Mao; Klavetter, Kyle C; Abel, Paul R; Davy, Nicholas C; Snider, Jonathan L; Heller, Adam; Mullins, C Buddie

    2012-07-25

    Electrodes composed of silicon nanoparticles (SiNP) were prepared by slurry casting and then electrochemically tested in a fluoroethylene carbonate (FEC)-based electrolyte. The capacity retention after cycling was significantly improved compared to electrodes cycled in a traditional ethylene carbonate (EC)-based electrolyte.

  1. Electrochemical performance of 0.5Li2MnO3-0.5Li(Mn0.375Ni0.375Co0.25)O2 composite cathode in pyrrolidinium-based ionic liquid electrolytes

    NASA Astrophysics Data System (ADS)

    Patra, Jagabandhu; Dahiya, Prem Prakash; Tseng, Chung-Jen; Fang, Jason; Lin, Yu-Wei; Basu, S.; Majumder, S. B.; Chang, Jeng-Kuei

    2015-10-01

    High-energy-density 0.5Li2MnO3-0.5Li(Mn0.375Ni0.375Co0.25)O2 composite cathodes for lithium rechargeable batteries are synthesized using an auto-combustion method. The electrode charge-discharge properties are studied at 25 and 50 °C in Li+-containing N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (BMP-TFSI) and N-propyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PMP-TFSI) ionic liquid (IL) electrolytes. The IL electrolytes have a high decomposition temperature (∼400 °C) and thus are ideal for high-safety applications. Compared to Li+/BMP-TFSI IL, Li+/PMP-TFSI IL exhibits higher ionic conductivity and lower viscosity. As a result, the composite cathode shows superior electrochemical performance in Li+/PMP-TFSI IL electrolyte. With the increase in cell temperature from 25 to 50 °C, the maximum capacities and rate capabilities of both IL cells improve significantly. Thus at 50 °C, discharge capacities of 304 mAh g-1 (@10 mA g-1) and 223 mAh g-1 (@100 mA g-1) are obtained for the Li+/PMP-TFSI cell. These capacities are superior to those for a control cell made with the same composite cathode and a conventional organic electrolyte. At elevated temperature, the cyclability of the composite cathode in the IL electrolytes is markedly higher than that obtained in a conventional organic electrolyte.

  2. Dehydrogenation kinetics and reversibility of LiAlH4-LiBH4 doped with Ti-based additives and MWCNT

    NASA Astrophysics Data System (ADS)

    Thaweelap, Natthaporn; Utke, Rapee

    2016-11-01

    Dehydrogenation kinetics and reversibility of LiAlH4-LiBH4 doped with Ti-based additives (TiCl3 and Ti-isopropoxide), multiwall carbon nanotubes (MWCNT), and MWCNT impregnated with Ti-based additives are proposed. Reduction of dehydrogenation temperature as well as improvements of kinetics and reversibility, especially decomposition of thermodynamically stable hydride (LiBH4) is obtained from the samples doped with Ti-isopropoxide and MWCNT. This can be due to the fact that the formations of LixAl(1-x)B2 and LiH-Al containing phase during dehydrogenation favor decomposition of LiH, leading to increment of hydrogen capacity, and stabilization of boron in solid state, resulting in improvement of reversibility. Besides, the curvatures and thermal conductivity of MWCNT benefit hydrogen diffusion and heat transfer during de/rehydrogenation. Nevertheless, deficient hydrogen content reversible is observed in all samples due to the irreversible of LiAlH4 and/or Li3AlH6 as well as the formation of stable phase (Li2B12H12) during de/rehydrogenation.

  3. Neutron scattering study on cathode LiMn{sub 2}O{sub 4} and solid electrolyte 5(Li{sub 2}O)(P{sub 2}O{sub 5})

    SciTech Connect

    Kartini, E. Putra, Teguh P. Jahya, A. K. Insani, A.; Adams, S.

    2014-09-30

    Neutron scattering is very important technique in order to investigate the energy storage materials such as lithium-ion battery. The unique advantages, neutron can see the light atoms such as Hydrogen, Lithium, and Oxygen, where those elements are negligible by other corresponding X-ray method. On the other hand, the energy storage materials, such as lithium ion battery is very important for the application in the electric vehicles, electronic devices or home appliances. The battery contains electrodes (anode and cathode), and the electrolyte materials. There are many challenging to improve the existing lithium ion battery materials, in order to increase their life time, cyclic ability and also its stability. One of the most scientific challenging is to investigate the crystal structure of both electrode and electrolyte, such as cathodes LiCoO{sub 2}, LiMn{sub 2}O{sub 4} and LiFePO{sub 4}, and solid electrolyte Li{sub 3}PO{sub 4}. Since all those battery materials contain Lithium ions and Oxygen, the used of neutron scattering techniques to study their structure and related properties are very important and indispensable. This article will review some works of investigating electrodes and electrolytes, LiMn{sub 2}O{sub 4} and 5(Li{sub 2}O)(P{sub 2}O{sub 5}), by using a high resolution powder diffraction (HRPD) at the multipurpose research reactor, RSG-Sywabessy of the National Nuclear Energy Agency (BATAN), Indonesia.

  4. Si doped T6 carbon structure as an anode material for Li-ion batteries: An ab initio study

    NASA Astrophysics Data System (ADS)

    Rajkamal, A.; Kumar, E. Mathan; Kathirvel, V.; Park, Noejung; Thapa, Ranjit

    2016-11-01

    First-principles calculations are performed to identify the pristine and Si doped 3D metallic T6 carbon structure (having both sp2 and sp3 type hybridization) as a new carbon based anode material. The π electron of C2 atoms (sp2 bonded) forms an out of plane network that helps to capture the Li atom. The highest Li storage capacity of Si doped T6 structure with conformation Li1.7Si1C5 produces theoretical specific capacity of 632 mAh/g which substantially exceeding than graphite. Also, open-circuit voltage (OCV) with respect to Li metal shows large negative when compared to the pristine T6 structure. This indicates modifications in terms of chemical properties are required in anode materials for practical application. Among various doped (Si, Ge, Sn, B, N) configuration, Si doped T6 structure provides a stable positive OCV for high Li concentrations. Likewise, volume expansion study also shows Si doped T6 structure is more stable with less pulverization and substantial capacity losses in comparison with graphite and silicon as an anode materials. Overall, mixed hybridized (sp2 + sp3) Si doped T6 structure can become a superior anode material than present sp2 hybridized graphite and sp3 hybridized Si structure for modern Lithium ion batteries.

  5. Si doped T6 carbon structure as an anode material for Li-ion batteries: An ab initio study

    PubMed Central

    Rajkamal, A.; Kumar, E. Mathan; Kathirvel, V.; Park, Noejung; Thapa, Ranjit

    2016-01-01

    First-principles calculations are performed to identify the pristine and Si doped 3D metallic T6 carbon structure (having both sp2 and sp3 type hybridization) as a new carbon based anode material. The π electron of C2 atoms (sp2 bonded) forms an out of plane network that helps to capture the Li atom. The highest Li storage capacity of Si doped T6 structure with conformation Li1.7Si1C5 produces theoretical specific capacity of 632 mAh/g which substantially exceeding than graphite. Also, open-circuit voltage (OCV) with respect to Li metal shows large negative when compared to the pristine T6 structure. This indicates modifications in terms of chemical properties are required in anode materials for practical application. Among various doped (Si, Ge, Sn, B, N) configuration, Si doped T6 structure provides a stable positive OCV for high Li concentrations. Likewise, volume expansion study also shows Si doped T6 structure is more stable with less pulverization and substantial capacity losses in comparison with graphite and silicon as an anode materials. Overall, mixed hybridized (sp2 + sp3) Si doped T6 structure can become a superior anode material than present sp2 hybridized graphite and sp3 hybridized Si structure for modern Lithium ion batteries. PMID:27892532

  6. Conducting polymer-doped polyprrrole as an effective cathode catalyst for Li-O{sub 2} batteries

    SciTech Connect

    Zhang, Jinqiang; Sun, Bing; Ahn, Hyo-Jun; Wang, Chengyin; Wang, Guoxiu

    2013-12-15

    Graphical abstract: - Highlights: • Doped polypyrrole as cathode catalysts for Li-O{sub 2} batteries. • Polypyrrole has an excellent redox capability to activate oxygen reduction. • Chloride doped polypyrrole demonstrated an improved catalytic performance in Li-O{sub 2} batteries. - Abstract: Polypyrrole conducting polymers with different dopants have been synthesized and applied as the cathode catalyst in Li-O{sub 2} batteries. Polypyrrole polymers exhibited an effective catalytic activity towards oxygen reduction in lithium oxygen batteries. It was discovered that dopant significantly influenced the electrochemical performance of polypyrrole. The polypyrrole doped with Cl{sup −} demonstrated higher capacity and more stable cyclability than that doped with ClO{sub 4}{sup −}. Polypyrrole conducting polymers also exhibited higher capacity and better cycling performance than that of carbon black catalysts.

  7. Structure and Stoichiometry in Supervalent Doped Li7La3 Zr2O12

    SciTech Connect

    Mukhopadhyay, Saikat; Thompson, Travis; Sakamoto, Jeff; Huq, Ashfia; Wolfenstine, Jeff; Allen, Jan L.; Bernstein, Noam; Stewart, Derek A.; Johannes, M. D.

    2015-04-20

    The oxide garnet material Li7La3 Zr2O12 shows remarkably high ionic conductivity when doped with supervalent ions that are charge compensated by Li vacancies and is currently one of the best candidates for development of a technologically relevant solid electrolyte. Determination of optimal dopant concentration, however, has remained a persistent problem due to the extreme difficulty of establishing the actual (as compared to nominal) stoichiometry of intentionally doped materials and by the fact that it is still not entirely clear what level of lattice expansion/contraction best promotes. ionic diffusion. By combining careful synthesis, neutron diffraction, high-resolution X-ray diffraction (XRD), Raman measurements, and density functional theory calculations, we show that structure and stoichiometry are intimately related such that the former can in many cases be used as a gauge of the latter. We show that different Li-vacancy creating supervalent ions (Al3+ vs Ta5+) affect the structure very differently, both in terms of the lattice constant, which is easily measurable, and hi terms of the local structure, which can be difficult or impossible to access experimentally but may have important ramifications for conduction. We carefully correlate the lattice constant to dopant type/concentration via Vegard's law and then further correlate these quantities to relevant local structural parameters. In conclusion, our work opens the possibility of developing a codopant scheme that optimizes the Li vacancy concentration and the lattice size simultaneously.

  8. A new solid polymer electrolyte incorporating Li10GeP2S12 into a polyethylene oxide matrix for all-solid-state lithium batteries

    NASA Astrophysics Data System (ADS)

    Zhao, Yanran; Wu, Chuan; Peng, Gang; Chen, Xiaotian; Yao, Xiayin; Bai, Ying; Wu, Feng; Chen, Shaojie; Xu, Xiaoxiong

    2016-01-01

    Li10GeP2S12 (LGPS) is incorporated into polyethylene oxide (PEO) matrix to fabricate composite solid polymer electrolyte (SPE) membranes. The lithium ion conductivities of as-prepared composite membranes are evaluated, and the optimal composite membrane exhibits a maximum ionic conductivity of 1.21 × 10-3 S cm-1 at 80 °C and an electrochemical window of 0-5.7 V. The phase transition behaviors for electrolytes are characterized by DSC, and the possible reasons for their enhanced ionic conductivities are discussed. The LGPS microparticles, acting as active fillers incorporation into the PEO matrix, have a positive effect on the ionic conductivity, lithium ion transference number and electrochemical stabilities. In addition, two kinds of all-solid-state lithium batteries (LiFeO4/SPE/Li and LiCoO2/SPE/Li) are fabricated to demonstrate the good compatibility between this new SPE membrane and different electrodes. And the LiFePO4/Li battery exhibits fascinating electrochemical performance with high capacity retention (92.5% after 50 cycles at 60 °C) and attractive capacities of 158, 148, 138 and 99 mAh g-1 at current rates of 0.1 C, 0.2 C, 0.5 C and 1 C at 60 °C, respectively. It is demonstrated that this new composite SPE should be a promising electrolyte applied in solid state batteries based on lithium metal electrode.

  9. The electrochemical reactions of pure In with Li and Na: anomalous electrolyte decomposition, benefits of FEC additive, phase transitions and electrode performance

    SciTech Connect

    Hawks, Samantha A; Baggetto, Loic; Bridges, Craig A; Veith, Gabriel M

    2014-01-01

    Indium thin films are evaluated as an anode material for Li-ion and Na-ion batteries (theoretical capacities of 1012 mAh g-1 for Li and 467 mAh g-1 for Na). The native surface oxides are responsible for the anomalous electrolyte decomposition during the first cycle while oxidized In species are found to be responsible for the electrolyte decomposition during the subsequent cycles. The presence of 5wt% FEC electrolyte additive suppresses the occurrence of the anomalous electrolyte decomposition during the first cycle but is not sufficient to prevent the decomposition upon further cycling from 0 to 2 V. Prevention of the anomalous decomposition can be achieved by restricting the charge cut-off, for instance at 1.1 V, or by using larger amounts of FEC. The In films show moderately good capacity retention with storage capacities when cycled with Li (950 mAh g-1) but significantly less when cycled with Na (125 mAh g-1). XRD data reveal that several known Li-In phases (i.e LiIn, Li3In2, LiIn2 and Li13In3) form during the electrochemical reaction. In contrast, the reaction with Na is severely limited. The largest amount of inserted Na is evidenced for cells short-circuited 40 hrs at 65C, for which the XRD data show the coexistence of NaIn, In, and an unknown phase. During cycling, mechanical degradation due to repeated expansion/shrinkage, evidenced by SEM, coupled with SEI formation is the primary source of the capacity fade. Finally, we show that the In thin films exhibit very high rate capability for both Li (100 C) and Na (30 C).

  10. A new approach: Li2S-P2S5 thin-films prepared by thermal evaporation as solid electrolytes

    NASA Astrophysics Data System (ADS)

    Woo, Sung Pil; Kakati, Nitul; Kim, In Yea; Lee, Seok Hee; Yoon, Young Soo

    2016-08-01

    Li2S-P2S5 thin-film solid electrolytes are synthesized by using room-temperature thermal evaporation for use as lithium-ion conductors for all-solid-state Li-ion batteries. The local structures of 75.51Li2S:24.49P2S5 and 77.64Li2S:22.36P2S5 prepared in this way have hetero units that facilitate lithium-ion mobility. The lithium-ion conductivity at room temperature for the 77.64Li2S:22.36P2S5 thin-film (4.0 × 10-6 S cm-1) is higher than that for the 75.51Li2S:24.49P2S5 thin-film (1.2 × 10-6 S cm-1). The increased ion conductivity in the 77.64Li2S:22.36P2S5 film is due to the additional local P2S7 4- structure that forms a glassy state during the thermal evaporation process. The local structure can lead to a high mobility of Li+ ions in the Li2S-P2S5 system due to the non-bridging sulfide ions. Lithium-ion-conducting thin-films prepared by using thermal evaporation, as reported in this study, are promising solid electrolytes.

  11. Allylic ionic liquid electrolyte-assisted electrochemical surface passivation of LiCoO2 for advanced, safe lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Mun, Junyoung; Yim, Taeeun; Park, Jang Hoon; Ryu, Ji Heon; Lee, Sang Young; Kim, Young Gyu; Oh, Seung M.

    2014-08-01

    Room-temperature ionic liquid (RTIL) electrolytes have attracted much attention for use in advanced, safe lithium-ion batteries (LIB) owing to their nonvolatility, high conductivity, and great thermal stability. However, LIBs containing RTIL-electrolytes exhibit poor cyclability because electrochemical side reactions cause problematic surface failures of the cathode. Here, we demonstrate that a thin, homogeneous surface film, which is electrochemically generated on LiCoO2 from an RTIL-electrolyte containing an unsaturated substituent on the cation (1-allyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, AMPip-TFSI), can avert undesired side reactions. The derived surface film comprised of a high amount of organic species from the RTIL cations homogenously covered LiCoO2 with a <25 nm layer and helped suppress unfavorable thermal reactions as well as electrochemical side reactions. The superior performance of the cell containing the AMPip-TFSI electrolyte was further elucidated by surface, electrochemical, and thermal analyses.

  12. Allylic ionic liquid electrolyte-assisted electrochemical surface passivation of LiCoO2 for advanced, safe lithium-ion batteries

    PubMed Central

    Mun, Junyoung; Yim, Taeeun; Park, Jang Hoon; Ryu, Ji Heon; Lee, Sang Young; Kim, Young Gyu; Oh, Seung M.

    2014-01-01

    Room-temperature ionic liquid (RTIL) electrolytes have attracted much attention for use in advanced, safe lithium-ion batteries (LIB) owing to their nonvolatility, high conductivity, and great thermal stability. However, LIBs containing RTIL-electrolytes exhibit poor cyclability because electrochemical side reactions cause problematic surface failures of the cathode. Here, we demonstrate that a thin, homogeneous surface film, which is electrochemically generated on LiCoO2 from an RTIL-electrolyte containing an unsaturated substituent on the cation (1-allyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, AMPip-TFSI), can avert undesired side reactions. The derived surface film comprised of a high amount of organic species from the RTIL cations homogenously covered LiCoO2 with a <25 nm layer and helped suppress unfavorable thermal reactions as well as electrochemical side reactions. The superior performance of the cell containing the AMPip-TFSI electrolyte was further elucidated by surface, electrochemical, and thermal analyses. PMID:25168309

  13. Observation of non-Fermi liquid behavior in hole-doped LiFe1 -xVxAs

    NASA Astrophysics Data System (ADS)

    Xing, L. Y.; Shi, X.; Richard, P.; Wang, X. C.; Liu, Q. Q.; Lv, B. Q.; Ma, J.-Z.; Fu, B. B.; Kong, L.-Y.; Miao, H.; Qian, T.; Kim, T. K.; Hoesch, M.; Ding, H.; Jin, C. Q.

    2016-09-01

    We synthesized a series of V-doped LiFe1 -xVxAs single crystals. The superconducting transition temperature Tc of LiFeAs decreases rapidly at a rate of 7 K per 1% V. The Hall coefficient of LiFeAs switches from negative to positive with 4.2% V doping, showing that V doping introduces hole carriers. This observation is further confirmed by the evaluation of the Fermi surface volume measured by angle-resolved photoemission spectroscopy (ARPES), from which a 0.3 hole doping per V atom introduced is deduced. Interestingly, the introduction of holes does not follow a rigid band shift. We also show that the temperature evolution of the electrical resistivity as a function of doping is consistent with a crossover from a Fermi liquid to a non-Fermi liquid. Our ARPES data indicate that the non-Fermi liquid behavior is mostly enhanced when one of the hole dx z/dy z Fermi surfaces is well nested by the antiferromagnetic wave vector to the inner electron Fermi surface pocket with the dx y orbital character. The magnetic susceptibility of LiFe1 -xVxAs suggests the presence of strong magnetic impurities following V doping, thus providing a natural explanation to the rapid suppression of superconductivity upon V doping.

  14. Observation of non-Fermi liquid behavior in hole-doped LiFe1-x VxAs

    DOE PAGES

    Xing, L. Y.; Shi, X.; Richard, P.; ...

    2016-09-28

    Here we synthesized a series of V-doped LiFe1₋xVxAs single crystals. The superconducting transition temperature Tc of LiFeAs decreases rapidly at a rate of 7 K per 1% V. The Hall coefficient of LiFeAs switches from negative to positive with 4.2% V doping, showing that V doping introduces hole carriers. This observation is further confirmed by the evaluation of the Fermi surface volume measured by angle-resolved photoemission spectroscopy (ARPES), from which a 0.3 hole doping per V atom introduced is deduced. Interestingly, the introduction of holes does not follow a rigid band shift. We also show that the temperature evolution ofmore » the electrical resistivity as a function of doping is consistent with a crossover from a Fermi liquid to a non-Fermi liquid. Our ARPES data indicate that the non-Fermi liquid behavior is mostly enhanced when one of the hole dxz/dyz Fermi surfaces is well nested by the antiferromagnetic wave vector to the inner electron Fermi surface pocket with the dxy orbital character. In conclusion, the magnetic susceptibility of LiFe1₋xVxAs suggests the presence of strong magnetic impurities following V doping, thus providing a natural explanation to the rapid suppression of superconductivity upon V doping.« less

  15. Structural and Electrochemical Consequences of Al and Ga Cosubstitution in Li7La3Zr2O12 Solid Electrolytes.

    PubMed

    Rettenwander, Daniel; Redhammer, Günther; Preishuber-Pflügl, Florian; Cheng, Lei; Miara, Lincoln; Wagner, Reinhard; Welzl, Andreas; Suard, Emmanuelle; Doeff, Marca M; Wilkening, Martin; Fleig, Jürgen; Amthauer, Georg

    2016-04-12

    Several "Beyond Li-Ion Battery" concepts such as all solid-state batteries and hybrid liquid/solid systems envision the use of a solid electrolyte to protect Li-metal anodes. These configurations are very attractive due to the possibility of exceptionally high energy densities and high (dis)charge rates, but they are far from being realized practically due to a number of issues including high interfacial resistance and difficulties associated with fabrication. One of the most promising solid electrolyte systems for these applications is Al or Ga stabilized Li7La3Zr2O12 (LLZO) based on high ionic conductivities and apparent stability against reduction by Li metal. Nevertheless, the fabrication of dense LLZO membranes with high ionic conductivity and low interfacial resistances remains challenging; it definitely requires a better understanding of the structural and electrochemical properties. In this study, the phase transition from garnet (Ia3̅d, No. 230) to "non-garnet" (I4̅3d, No. 220) space group as a function of composition and the different sintering behavior of Ga and Al stabilized LLZO are identified as important factors in determining the electrochemical properties. The phase transition was located at an Al:Ga substitution ratio of 0.05:0.15 and is accompanied by a significant lowering of the activation energy for Li-ion transport to 0.26 eV. The phase transition combined with microstructural changes concomitant with an increase of the Ga/Al ratio continuously improves the Li-ion conductivity from 2.6 × 10(-4) S cm(-1) to 1.2 × 10(-3) S cm(-1), which is close to the calculated maximum for garnet-type materials. The increase in Ga content is also associated with better densification and smaller grains and is accompanied by a change in the area specific resistance (ASR) from 78 to 24 Ω cm(2), the lowest reported value for LLZO so far. These results illustrate that understanding the structure-properties relationships in this class of materials allows

  16. Structural and Electrochemical Consequences of Al and Ga Cosubstitution in Li7La3Zr2O12 Solid Electrolytes

    PubMed Central

    2016-01-01

    Several “Beyond Li-Ion Battery” concepts such as all solid-state batteries and hybrid liquid/solid systems envision the use of a solid electrolyte to protect Li-metal anodes. These configurations are very attractive due to the possibility of exceptionally high energy densities and high (dis)charge rates, but they are far from being realized practically due to a number of issues including high interfacial resistance and difficulties associated with fabrication. One of the most promising solid electrolyte systems for these applications is Al or Ga stabilized Li7La3Zr2O12 (LLZO) based on high ionic conductivities and apparent stability against reduction by Li metal. Nevertheless, the fabrication of dense LLZO membranes with high ionic conductivity and low interfacial resistances remains challenging; it definitely requires a better understanding of the structural and electrochemical properties. In this study, the phase transition from garnet (Ia3̅d, No. 230) to “non-garnet” (I4̅3d, No. 220) space group as a function of composition and the different sintering behavior of Ga and Al stabilized LLZO are identified as important factors in determining the electrochemical properties. The phase transition was located at an Al:Ga substitution ratio of 0.05:0.15 and is accompanied by a significant lowering of the activation energy for Li-ion transport to 0.26 eV. The phase transition combined with microstructural changes concomitant with an increase of the Ga/Al ratio continuously improves the Li-ion conductivity from 2.6 × 10–4 S cm–1 to 1.2 × 10–3 S cm–1, which is close to the calculated maximum for garnet-type materials. The increase in Ga content is also associated with better densification and smaller grains and is accompanied by a change in the area specific resistance (ASR) from 78 to 24 Ω cm2, the lowest reported value for LLZO so far. These results illustrate that understanding the structure–properties relationships in this class of materials

  17. Chrystal structure properties of Al-doped Li4Ti5O12 synthesized by solid state reaction method

    NASA Astrophysics Data System (ADS)

    Sandi, Dianisa Khoirum; Priyono, Slamet; Suryana, Risa

    2016-02-01

    This research aim is to analyze the effect of Aluminum (Al) doping in the structural properties of Al-doped Li4Ti5O12 as anode in lithium ion battery. Al-doped Li4Ti5O12 powders were synthesized by solid state reaction method. LiOH.H2O, TiO2, and Al2O3 were raw materials. These materials were milled for 15 h, calcined at temperature of 750oC and sintered at temperature of 800oC. Mole percentage of doping Al (x) was varied at x=0; x=0.025; and x =0.05. Al-doped Li4Ti5O12 powders were synthesized by solid state reaction method. X-ray diffraction was employed to determine the structure of Li4Ti5O12. The PDXL software was performed on the x-ray diffraction data to estimate the phase percentage, the lattice parameter, the unit cell volume, and the crystal density. Al-doped Li4Ti5O12 has cubic crystal structure. Al-doping at x=0 and x=0.025 does not change the phase as Li4Ti5O12 while at x=0.050 the phase changes to the LiTiAlO4. The diffraction patterns show that the angle shifted to the right as the increase of x which indicated that Al substitute Ti site. Percentage of Li4Ti5O12 phase at x=0 and x=0.025 was 97.8% and 96.8%, respectively. However, the lattice parameters, the unit cell volume, and the crystal density does not change significantly at x=0; x=0.025; and x=0.050. Based on the percentage of Li4Ti5O12 phase, the Al-doped Li at x=0 and x=0.025 is promising as a lithium battery anode.

  18. Gas chromatography/mass spectrometry as a suitable tool for the Li-ion battery electrolyte degradation mechanisms study.

    PubMed

    Gachot, Grégory; Ribière, Perrine; Mathiron, David; Grugeon, Sylvie; Armand, Michel; Leriche, Jean-Bernard; Pilard, Serge; Laruelle, Stéphane

    2011-01-15

    To allow electric vehicles to be powered by Li-ion batteries, scientists must understand further their aging processes in view to extend their cycle life and safety. For this purpose, we focused on the development of analytical techniques aiming at identifying organic species resulting from the degradation of carbonate-based electrolytes (EC-DMC/LiPF(6)) at low potential. As ESI-HRMS provided insightful information to the mechanism and chronological formation of ethylene oxide oligomers, we implemented "gas" GC/MS experiments to explore the lower mass range corresponding to highly volatile compounds. With the help of chemical simulation tests, we were able to discriminate their formation pathways (thermal and/or electrochemical) and found that most of the degradation compounds originate from the electrochemically driven linear alkyl carbonate reduction upon cycling and to a lesser extent from a two-step EC reduction. Deduced from these results, we propose an overall electrolyte degradation scheme spanning the entire mass range and the chemical or electrochemical type of processes.

  19. Crystalline Li(sub 3)PO(sub 4)/SiO(sub 4) solid solutions as an electrolyte for film batteries using sputtered cathode layers

    NASA Technical Reports Server (NTRS)

    Whitacre, J. F.; West, W. C.

    2003-01-01

    Crystalline solid solutions of 1:1 Li3PO4/SiO4 were synthesized and tested electrochemically using thin film, physical vapor deposited electrodes. After cathode deposition, the electrolyte/cathode structures were annealed at 700 degrees Celsius for 2 hours, a process that resulted in cathode crystallization without encouraging deleterious interfacial reactions. Results indicate that the electrolyte functioned well in this configuration.

  20. Poly(ethylenglycol)dimethylether-lithium bis(trifluoromethanesulfonyl)imide, PEG500DME-LiTFSI, as high viscosity electrolyte for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Bernhard, Rebecca; Latini, Alessandro; Panero, Stefania; Scrosati, Bruno; Hassoun, Jusef

    2013-03-01

    In this paper we report a poly(ethylenglycol)dimethylether-lithium bis(trifluoromethanesulfonyl) imide (PEG500DME-LiTFSI) as high viscosity, safe electrolyte for lithium ion batteries. The high molecular weight of the end-capped ether solvent is reflected as low vapor pressure and excellent thermal stability of the electrolyte, as demonstrated by thermogravimetry, this resulting in remarkable safety content. The electrochemical impedance spectroscopy study of the electrolyte demonstrates a Li-transference number of 0.48, a conductivity of the order of 10-3 S cm-1, and a high interphase stability with the lithium metal, the linear sweep voltammetry indicates an electrochemical stability window extending up to 4.8 V vs. Li/Li+. Furthermore, promising electrochemical performances in terms of reversibility, cycling stability and low charge-discharge polarization are observed using the electrolyte in lithium and in lithium ion batteries using lithium cobalt oxide (LCO) as cathode and titanium dioxide (TiO2) as anode. Hence, this electrolyte is a promising candidate for applications in safe, high performance lithium ion batteries.

  1. Investigation of Ionic Conductivity of Nanocomposite Polymer Electrolytes Based On PVDF-HFP/PVC Blend, LiClO4 and TiO2 Nanofiller

    NASA Astrophysics Data System (ADS)

    Basri, N. H.; Mohamed, N. S.

    2010-07-01

    The effects of nanosized TiO2 on the conductivity of PVDF-HFP/PVC-LiClO4 was studied by means of impedance spectroscopy and x-ray diffraction (XRD). The addition of TiO2 nanofiller increases the crystalline phase fraction but slightly increases the conductivity of the PVDF-HFP/PVC-LiClO4 complex. The increase in conductivity is attributed to the formation of highly conducting layer at the electrolyte/filler interface. The temperature dependence of conductivity obeys the VTF type behaviour while the transference number confirms that the electrolyte containing 6 wt.% TiO2 is an ionic conductor are ionic conductors.

  2. Nitrogen and carbon doped titanium oxide as an alternative and durable electrocatalyst support in polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Dhanasekaran, P.; Vinod Selvaganesh, S.; Bhat, Santoshkumar D.

    2016-02-01

    Nitrogen and carbon doped titanium oxide as an alternative and ultra-stable support to platinum catalysts is prepared and its efficiency is determined by polymer electrolyte fuel cell. Nitrogen and carbon doped titanium oxide is prepared by varying the melamine ratio followed by calcination at 900 °C. Platinum nanoparticles are deposited onto doped and undoped titanium oxide by colloidal method. The doping effect, surface morphology, chemical oxidation state and metal/metal oxide interfacial contact are studied by X-ray diffraction, Raman spectroscopy, high resolution transmission electron microscopy and X-ray photo electron spectroscopy. The nitrogen and carbon doping changes both electronic and structural properties of titanium oxide resulting in enhanced oxygen reduction reaction activity. The platinum deposited on optimum level of nitrogen and carbon doped titanium oxide exhibits improved cell performance in relation to platinum on titanium oxide electrocatalysts. The effect of metal loading on cathode electrocatalyst is investigated by steady-state cell polarization. Accelerated durability test over 50,000 cycles for these electrocatalysts suggested the improved interaction between platinum and nitrogen and carbon doped titanium oxide, retaining the electrochemical surface area and oxygen reduction performance as comparable to platinum on carbon support.

  3. Ionic conductivity and dielectric permittivity of PEO-LiClO{sub 4} solid polymer electrolyte plasticized with propylene carbonate

    SciTech Connect

    Das, S.; Ghosh, A.

    2015-02-15

    We have studied ionic conductivity and dielectric permittivity of PEO-LiClO{sub 4} solid polymer electrolyte plasticized with propylene carbonate. Differential scanning calorimetry and X-ray diffraction studies confirm minimum volume fraction of crystalline phase for the polymer electrolyte with 40 wt. % propylene carbonate. The ionic conductivity exhibits a maximum for the same composition. The temperature dependence of the ionic conductivity has been well interpreted using Vogel-Tamman-Fulcher equation. Ion-ion interactions in the polymer electrolytes have been studied using Raman spectra and the concentrations of free ions, ion-pairs and ion-aggregates have been determined. The ionic conductivity increases due to the increase of free ions with the increase of propylene carbonate content. But for higher content of propylene carbonate, the ionic conductivity decreases due to the increase of concentrations of ion-pairs and ion-aggregates. To get further insights into the ion dynamics, the experimental data for the complex dielectric permittivity have been studied using Havriliak–Negami function. The variation of relaxation time with temperature obtained from this formalism follows Vogel-Tamman-Fulcher equation similar to the ionic conductivity.

  4. Conduction mechanisms in concentrated LiI-polyethylene oxide-Al{sub 2}O{sub 3}-based solid electrolytes

    SciTech Connect

    Golodnitsky, D.; Ardel, G.; Strauss, E.; Peled, E.; Lareah, Y.; Rosenberg, Y.

    1997-10-01

    The ionic conductivity of concentrated LiI-polyethylene oxide P(EO){sub n} high surface area oxide composite polymer electrolytes has been investigated. Two different Arrhenius dependences for concentrated composite polymer electrolytes (CPEs) have been identified. The first one is characterized by an inflection point at about 80 C, and the second, by a conductivity jump. The authors have suggested that in CPEs, where 3electrolytes (CSEs, n{le}3), is about 40% of that for CPEs. The authors believe that the preferred conduction path in even more concentrated CPEs, which are defined as CSEs, is interfacial conduction. Differential scanning calorimetry, scanning electron microscopy, and X-ray data, presented here, are evidence supporting the view. The effects of several parameters including type and content of oxide matrix, Li salt to ethylene oxide ratio, copolymers, and solvents on polymer electrolyte conductivity (especially at T >T{sub k}orT{sub jump}) and on Ea have been studied (T{sub jump}=temperature of the conductivity jump). The addition of small quantities of ethylene carbonate, poly(methyl methacrylate), and polyacrylonitrile were found to be beneficial while poly(methyl acrylate), poly(butyl acrylate), and poly(vinylidene fluoride) additions made the polymer electrolyte stiffer and less conductive. MgO, Al{sub 2}O{sub 3}, and potassium aluminosilicate muscovite mica based CSEs have similar conductivity. Results clearly demonstrated the depression of CPE crystallinity by addition of fine Al{sub 2}O{sub 3} powder, ethylene carbonate, and poly(ethylene glycol) dimethyl ether, in agreement with the conductivity enhancement of the CPE.

  5. Investigation of the Decomposition Mechanism of Lithium Bis(oxalate)borate (LiBOB) Salt in the Electrolyte of an Aprotic Li–O2 Battery

    SciTech Connect

    Lau, Kah Chun; Lu, Jun; Low, John; Peng, Du; Wu, Huiming; Albishri, Hassan M.; Al-Hady, D. Abd; Curtiss, Larry A.; Amine, Khalil

    2014-03-13

    The stability of the lithium bis(oxalate) borate (LiBOB) salt against lithium peroxide (Li2O2) formation in an aprotic Li–O2 (Li–air) battery is investigated. From theoretical and experimental findings, we find that the chemical decomposition of LiBOB in electrolytes leads to the formation lithium oxalate during the discharge of a Li–O2 cell. According to density functional theory (DFT) calculations, the formation of lithium oxalate as the reaction product is exothermic and therefore is thermodynamically feasible. This reaction seems to be independent of solvents used in the Li–O2 cell, and therefore LiBOB is probably not suitable to be used as the salt in Li–O2 cell electrolytes.

  6. Studies on structural, thermal and AC conductivity scaling of PEO-LiPF6 polymer electrolyte with added ionic liquid [BMIMPF6

    NASA Astrophysics Data System (ADS)

    Chaurasia, S. K.; Saroj, A. L.; Shalu, Singh, V. K.; Tripathi, A. K.; Gupta, A. K.; Verma, Y. L.; Singh, R. K.

    2015-07-01

    Preparation and characterization of polymer electrolyte films of PEO+10wt.% LiPF6 + xwt.% BMIMPF6 (1-butyl-3-methylimidazolium hexafluorophosphate) containing dopant salt lithium hexafluorophosphate (LiPF6) and ionic liquid (BMIMPF6) having common anion PF6 - are reported. The ionic conductivity of the polymer electrolyte films has been found to increase with increasing concentration of BMIMPF6 in PEO+10 wt.% LiPF6 due to the plasticization effect of ionic liquid. DSC and XRD results show that the crystallinity of polymer electrolyte decreases with BMIMPF6 concentration which, in turn, is responsible for the increase in ionic conductivity. FTIR spectroscopic study shows the complexation of salt and/or ionic liquid cations with the polymer backbone. Ion dynamics behavior of PEO+LiPF6 as well as PEO+LiPF6 + BMIMPF6 polymer electrolytes was studied by frequency dependent conductivity, σ(f) measurements. The values σ(f) at various temperatures have been analyzed in terms of Jonscher power law (JPL) and scaled with respect to frequency which shows universal power law characteristics at all temperatures.

  7. Growth and scintillation properties of Tb doped LiGdF4/LiF eutectic scintillator

    NASA Astrophysics Data System (ADS)

    Kamada, Kei; Hishinuma, Kosuke; Kurosawa, Shunsuke; Yamaji, Akihiro; Shoji, Yasuhiro; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira

    2016-11-01

    Tb-doped LiGdF4-LiF eutectics were grown at various growth rate and their directionally solidified eutectic (DSE) system has been investigated. Well aligned fiber like eutectic structure with around 1.7 μm in diameter and 1200 μm in maximum length was obtained the growth speed of 0.15 mm/min. The sample showed optical transparency like bundle optical fibers and around 40% of transmittance at 1.5 mm thick was achieved in 380-630 nm range. The expected 380-630 nm emission exited by UV and α-ray, and 270-330 nm excitation of Tb3+8S -6P transition have been observed. The weak emission of Gd3+ 4f-4f transition at 310 nm was also observed under alpha-ray excitation. The Observed excitation bands peaking at around 275 nm and 310 nm correspond respectively to the 8S7/2- 6I7/2 and 8S7/2-6PJ absorption bands of Gd3+.

  8. The electrochemical reactions of pure indium with Li and Na: Anomalous electrolyte decomposition, benefits of FEC additive, phase transitions and electrode performance

    NASA Astrophysics Data System (ADS)

    Webb, Samantha A.; Baggetto, Loïc; Bridges, Craig A.; Veith, Gabriel M.

    2014-02-01

    Indium thin films were evaluated as an anode material for Li-ion and Na-ion batteries (theoretical capacities of 1012 mAh g-1 for Li and 467 mAh g-1 for Na). XRD data reveal that several known Li-In phases (LiIn, Li3In2, LiIn2 and Li13In3) form providing 950 mAh g-1 reversible capacity. In contrast, the reaction with Na is severely limited (75-125 mAh g-1). XRD data of short-circuited cells (40 h at 65 °C) show the coexistence of NaIn, In, and an unknown NaxIn phase. In electrodes exhibit anomalous electrolyte decomposition characterized by large discharge plateaus at 1.4 V vs Li/Li+ and 0.9 V vs Na/Na+. The presence of 5 wt% fluoroethylene carbonate additive suppresses the occurrence of the electrolyte decomposition during the first cycle but does not necessarily prevent it upon further cycling. Prevention of the anomalous decomposition can be achieved by restricting the (dis)charge voltages, increasing the current or by using larger amounts of FEC. The native surface oxides (In2O3) are responsible for the pronounced electrolyte decomposition during the first cycle while other In3+ species are responsible during the subsequent cycles. We also show that indium electrodes can exhibit very high rate capability for both Li (100 C-rate) and Na (30 C-rate).

  9. Study of a Li doped CsI scintillator crystal as a neutron detector

    NASA Astrophysics Data System (ADS)

    Madi Filho, T.; Pereira, M. C. C.; Berretta, J. R.; Cárdenas, J. P. N.

    2015-07-01

    The radiation monitoring system is an important requirement in the premises of a nuclear reactor. A variety of types of radiation (neutrons. gamma. beta and fission products) exist in a reactor. associated to the broad energy spectrum of these radiations. implying the need of detectors to be used in the reactor system and security. as well as radiation monitoring. As the neutron sources are associated to gamma radiation. it is necessary that the neutron detecting system may be capable to discriminate the gamma interference. In our work environment. there are two Nuclear Research Reactors and a neutron irradiator with two AmBe sources (592GBq of Am. each). These conditions warrant the development of new types of detectors. Due to the absence of charge in the neutron. it is necessary to use a converter material that generates radiations capable to produce signals in the detector. Materials with high cross section. like Li or B. are used for this purpose. The CsIcrystal doped with 6Li has been studied. The concentration of the lithium doping element (Li) studied was 10-3M. The detector test was done using an AmBe source (37GBq) and gamma sources. The crystal was coupled to a photomultiplier.

  10. Growth and property of Zn-doped near-stoichiometric LiTaO 3 crystal

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Wang, Dongpeng; Xu, Yuheng

    2010-05-01

    Near-stoichiometric LiTaO 3 (SLT) and Zn-doped near-stoichiometric LiTaO 3 (Zn:SLT) crystals with 10-15 mm in diameter and 10 mm in length were grown by using TSSG technique with K 2O as the flux. The effect of adding amount of K 2O was discussed in the growing process. The crystals were characterized by inductively coupled plasma-optical emission (ICP-OES), X-ray diffraction (XRD) and differential thermal analysis (DTA). The lattice constants of Zn:SLT were smaller than those of SLT and Curie temperature was higher than that of SLT. It was found that Zn doping is an efficient way to improve the optical damage resistance ability of SLT crystal. Compared with SLT crystal, Zn:SLT exhibited a much higher optical damage threshold, more than 500 MW/cm 2, which was attributed to Zn self-compensated effect that formed the charge compensated complexes, (Zn Ta) 3--3(Zn Li) + in SLT crystal.

  11. N-doped pierced graphene microparticles as a highly active electrocatalyst for Li-air batteries

    NASA Astrophysics Data System (ADS)

    Yuan, Tao; Zhang, Weimin; Li, Wen-Ting; Song, Chuantao; He, Yu-Shi; Razal, Joselito M.; Ma, Zi-Feng; Chen, Jun

    2015-06-01

    In this work we report a novel scalable strategy to prepare a lithium-air battery electrode from 3D N-doped pierced graphene microparticles (N-PGM) with highly active performance. This approach has combined the merits of spray drying technology and the hard template method. The pierced structured graphene microparticles were characterized physically and electrochemically. An x-ray photoelectron spectrometer and Raman spectra have revealed that the novel structure possesses a higher N-doping level than conventional graphene without the pierced structure. A much higher BET surface area was also achieved for the N-PGM than the conventional N-doped graphene microparticles (N-GM). Cyclic voltammetry indicated that the lithium-air battery with the N-PGM electrode has a better utilization for the graphene mass and a higher void volume for Li2O2 formation than that of the N-GM electrode. N-PGM also exhibits improved decomposition kinetics for Li oxide species yielded in the cathodic reaction. Charge and discharge measurements showed that the N-PGM lithium-air battery achieved an improved specific capacity and an enhanced cycle performance than when an N-GM electrode is used.

  12. Investigation of Yb-doped LiLuF4 single crystals for optical cooling

    NASA Astrophysics Data System (ADS)

    Volpi, Azzurra; Cittadino, Giovanni; Di Lieto, Alberto; Cassanho, Arlete; Jenssen, Hans P.; Tonelli, Mauro

    2017-01-01

    Optical cooling of solids, relying on annihilation of lattice phonons via anti-Stokes fluorescence, is an emerging technology that is rapidly advancing. The development of high-quality Yb-doped fluoride single crystals definitely led to cryogenic and sub-100-K operations, and the potential for further improvements has not been exhausted by far. Among fluorides, so far the best results have been achieved with Yb-doped LiYF4 (YLF) single crystals, with a record cooling to 91 K of a stand-alone YLF:10%Yb. We report on preliminary investigation of optical cooling of an LiLuF4 (LLF) single crystal, an isomorph of YLF where yttrium is replaced by lutetium. Different samples of 5% Yb-doped LLF single crystals have been grown and optically characterized. Optical cooling was observed by exciting the Yb transition in single-pass at 1025 nm and the cooling efficiency curve has been measured detecting the heating/cooling temperature change as a function of pumping laser frequency.

  13. Fire behavior of carbonates-based electrolytes used in Li-ion rechargeable batteries with a focus on the role of the LiPF6 and LiFSI salts

    NASA Astrophysics Data System (ADS)

    Eshetu, Gebrekidan Gebresilassie; Bertrand, Jean-Pierre; Lecocq, Amandine; Grugeon, Sylvie; Laruelle, Stephane; Armand, Michel; Marlair, Guy

    2014-12-01

    A detailed investigation of the combustion behavior of LiPF6 or LiFSI-based carbonate electrolytes was conducted with the objective of getting better knowledge of lithium-ion battery system fire induced thermal and chemical threats. The well-controlled experimental conditions provided by the Tewarson calorimeter have enabled the accurate evaluation of fire hazard rating parameters such as heat release rate and effective heat of combustion and the quantification of toxic effluents (HF, SO2, NOx…). Results have shown that all the electrolytes tested burn in phases depending on the flammability nature of their mixture constituents. The first stage of combustion is solely governed by the more volatile solvent (linear carbonate) and the influence of adding salt comes into effect predominantly in the second stage. It has been also shown that combustion enthalpy of electrolytes lies in the solvent mixture, irrespective of the salt added. The fire induced toxicity in well-ventilated conditions is found to be mainly dictated by the salt and its chemical structure, showing very limited concerns that emanate from the organic solvents.

  14. Excellent stability of a lithium-ion-conducting solid electrolyte upon reversible Li+/H+ exchange in aqueous solutions

    SciTech Connect

    Ma, Cheng; Rangasamy, Ezhiylmurugan; Liang, Chengdu; Sakamoto, Jeffrey; More, Karren Leslie; Chi, Miaofang

    2014-10-21

    Batteries with an aqueous catholyte and a Li metal anode have attracted interest owing to their exceptional energy density and high charge/discharge rate. The long-term operation of such batteries requires that the solid electrolyte separator between the anode and aqueous solutions must be compatible with Li and stable over a wide pH range. Unfortunately, no such compound has yet been reported. In this study, an excellent stability in neutral and strongly basic solutions was observed when using the cubic Li7La3Zr2O12 garnet as a Li-stable solid electrolyte. The material underwent a Li+/H+ exchange in aqueous solutions. Nevertheless, its structure remained unchanged even under a high exchange rate of 63.6%. When treated with a 2 M LiOH solution, the Li+/H+ exchange was reversed without any structural change. Furthermore, these observations suggest that cubic Li7La3Zr2O12 is a promising candidate for the separator in aqueous lithium batteries.

  15. Effects of Nb-doped on the structure and electrochemical performance of LiFePO{sub 4}/C composites

    SciTech Connect

    Ma, Zhipeng; Shao, Guangjie; Wang, Guiling; Zhang, Ying; Du, Jianping

    2014-02-15

    The olivine-type niobium doping Li{sub 1−x}Nb{sub x}FePO{sub 4}/C (x=0, 0.005, 0.010, 0.015, 0.025) cathode materials were synthesized via a two-step ball milling solid state reaction. The effects of Nb doping were charactered by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), galvanostatic intermittent titration technique (GITT), cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and galvanostatic charge–discharge. It is found that Nb doping enlarges the interplanar distance of crystal plane parallel to [0 1 0] direction in LiFePO{sub 4}. In other words, it widens the one dimensional diffusion channels of Li{sup +} along the [0 1 0] direction. Electrochemical test results indicate that the Li{sub 0.99}Nb{sub 0.01}FePO{sub 4}/C composite exhibits the best electrochemical performance with initial special discharge capacity of 139.3 mA h g{sup −1} at 1 C rate. The present synthesis route is promising in making the solid state reaction method more practical for preparation of the LiFePO{sub 4} material. - Graphical abstract: The proper amount of Nb doping widens the one dimensional diffusion channels of Li{sup +} along the [0 1 0] direction. Display Omitted - Highlights: • The Nb doping LiFePO{sub 4}/C is prepared by a facile two-step ball milling solid state reaction. • The sample possesses the better high-rate performance. • The tap density of Li{sub 0.99}Nb{sub 0.01}FePO{sub 4}/C sample is 1.76 g cm{sup −3}.

  16. Enhanced ionic conductivity with Li7O2Br3 phase in Li3OBr anti-perovskite solid electrolyte

    SciTech Connect

    Zhu, Jinlong; Li, Shuai; Zhang, Yi; Howard, John W.; Lu, Xujie; Li, Yutao; Wang, Yonggang; Kumar, Ravhi S.; Wang, Liping; Zhao, Yusheng

    2016-09-07

    Cubic anti-perovskites with general formula Li3OX (X = Cl, Br, I) were recently reported as superionic conductors with the potential for use as solid electrolytes in all-solid-state lithium ion batteries. These electrolytes are nonflammable, low-cost, and suitable for thermoplastic processing. However, the primary obstacle of its practical implementation is the relatively low ionic conductivity at room temperature. In this work, we synthesized a composite material consisting of two anti-perovskite phases, namely, cubic Li3OBr and layered Li7O2Br3, by solid state reaction routes. The results indicate that with the phase fraction of Li7O2Br3 increasing to 44 wt. %, the ionic conductivity increased by more than one order of magnitude compared with pure phase Li3OBr. Formation energy calculations revealed the meta-stable nature of Li7O2Br3, which supports the great difficulty in producing phase-pure Li7O2Br3 at ambient pressure. Here, methods of obtaining phase-pure Li7O2Br3 will continue to be explored, including both high pressure and metathesis techniques.

  17. First Tests of 6Li Doped Glass Scintillators for Ultracold Neutron Detection

    PubMed Central

    Ban, G.; Fléchard, X.; Labalme, M.; Lefort, T.; Liénard, E.; Naviliat-Cuncic, O.; Fierlinger, P.; Kirch, K.; Bodek, K.; Geltenbort, P.

    2005-01-01

    We report the results of test measurements aimed at determining the performances of 6Li doped glass scintillators for the detection of ultra-cold neutrons. Four types of scintillators, GS1, GS3, GS10 and GS20, which differ by their 6Li concentrations, have been tested. The signal to background separation is fully acceptable. The relative detection efficiencies have been determined as a function of the neutron velocity. We find that GS10 has a higher efficiency than the others for the detection of neutrons with velocities below 7 m/s. Two pieces of scintillators have been irradiated with a high flux of cold neutrons to test the radiation hardness of the glasses. No reduction in the pulse height has been observed up to an absorbed neutron dose of 1 × 1013 cm−3. PMID:27308137

  18. Solid electrolytes

    DOEpatents

    Abraham, Kuzhikalail M.; Alamgir, Mohamed

    1993-06-15

    This invention pertains to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of solvates of Li salts immobilized (encapsulated) in a solid organic polymer matrix. In particular, this invention relates to solid polymer electrolytes derived by immobilizing complexes (solvates) formed between a Li salt such as LiAsF.sub.6, LiCF.sub.3 SO.sub.3 or LiClO.sub.4 and a mixture of aprotic organic solvents having high dielectric constants such as ethylene carbonate (EC) (dielectric constant=89.6) and propylene carbonate (PC) (dielectric constant=64.4) in a polymer matrix such as polyacrylonitrile, poly(tetraethylene glycol diacrylate), or poly(vinyl pyrrolidinone).

  19. Investigations on spectroscopic properties of Er3+-doped Li-Zn fluoroborate glass

    NASA Astrophysics Data System (ADS)

    Thomas, Sunil; Sajna, M. S.; George, Rani; Rasool, Sk. Nayab; Joseph, Cyriac; Unnikrishnan, N. V.

    2015-09-01

    Er3+-doped Li-Zn fluoroborate glass was synthesized via melt quenching technique. Optical properties of the glass were investigated by UV-Vis-NIR absorption and emission spectra. To evaluate the nature of Er3+-ligand bond in the glass network, nephelauxetic ratios and bonding parameter were calculated. Judd-Ofelt analysis and hence the radiative properties of the present glass system were evaluated for ascertaining the suitability of the glass for laser applications and compared those with the emission spectra. Absorption cross-sections have been calculated from the absorption spectrum and stimulated emission cross-sections were estimated using McCumber theory for 4I13/2 ↔ 4I15/2 transitions. The results of the present glass were compared with those obtained for some other Er3+-doped glass systems.

  20. Transport Properties of xAgI-(1-x)LiPO3 Composite Electrolytes

    NASA Astrophysics Data System (ADS)

    Singh, D. P.; Shahi, K.; Kar, K. K.

    2011-07-01

    xAgI-(1-x) LiPO3 composite glasses were made by quenching of molten mixture. XRD confirms that γ-AgI is stabilized in LiPO3 glass matrix. A room temperature conductivity of ˜10-3 S/cm is achieved in the composite glass. The ac conductivity follows Jonscher power law (JPL). Higher composition samples also obey time temperature superposition scaling.

  1. Current limit diagrams for dendrite formation in solid-state electrolytes for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Raj, R.; Wolfenstine, J.

    2017-03-01

    We build upon the concept that nucleation of lithium dendrites at the lithium anode-solid state electrolyte interface is instigated by the higher resistance of grain boundaries that raises the local electro-chemical potential of lithium, near the lithium-electrode. This excess electro-chemo-mechanical potential, however, is reduced by the mechanical back stress generated when the dendrite is formed within the electrolyte. These parameters are coalesced into an analytical model that prescribes a specific criterion for dendrite formation. The results are presented in the form of current limit diagrams that show the "safe" and "fail" regimes for battery function. A higher conductivity of the electrolyte can reduce dendrite formation.

  2. Growth of thin, c-axis oriented Sr-doped LaP3O9 electrolyte membranes in condensed phosphoric acid solutions

    NASA Astrophysics Data System (ADS)

    Hatada, Naoyuki; Takahashi, Kota; Adachi, Yoshinobu; Uda, Tetsuya

    2016-08-01

    Proton-conducting Sr-doped LaP3O9 has potential application as electrolytes in intermediate temperature fuel cells, but reduction of the electrical resistance of the electrolyte membranes is necessary for practical applications. In this study, we focused on reducing the resistance by reducing the electrolyte thickness, while maintaining a preferable microstructure for proton conduction (c-axis orientation and absence of the small-crystal layer). Thin, c-axis oriented Sr-doped LaP3O9 membranes were successfully obtained in condensed phosphoric acid solutions by a novel "two-step precipitation method". In this method, Sr-doped LaP3O9 powder was artificially deposited on the surface of the carbon paper supports as seeds, and then columnar crystals were grown "downward" in the solutions. We expect that this method will be utilized to produce LaP3O9 electrolyte membranes with lower electrical resistance.

  3. In Situ Raman Microscopy of a Single Graphite Microflake Electrode in a Li(+)-containing Electrolyte

    NASA Technical Reports Server (NTRS)

    Shi, Qing-Fang; Dokko, Kaoru; Scherson, Daniel A.

    2003-01-01

    Highly detailed Raman spectra from a single KS-44 graphite microflake electrode as a function of the applied potential have been collected in situ using a Raman microscope and a sealed spectroelectrochemical cell isolated from the laboratory environment. Correlations were found between the Raman spectral features and the various Li(+) intercalation stages while recording in real time Raman spectra during a linear potential scan from 0.7 down ca. 0.0V vs Li/Li(+) at a rate of 0.1 mV/s in a 1M LiClO4 solution in a 1:l (by volume) ethylene carbonate (EC):diethyl carbonate (DEC) mixture. In particular, clearly defined isosbestic points were observed for data collected in the potential range where the transition between dilute phase 1 and phase 4 of lithiated graphite is known to occur, i.e. 0.157 < E < 0.215 vs Li/Li(+). Statistical analysis of the spectroscopic data within this region made it possible to determine independently the fraction of each of the two phases present as a function of potential without relying on coulometric information and then predict, based on the proposed stoichiometry for the transition, a spectrally-derived voltammetric feature.

  4. LiI-doped N,N-dimethyl-pyrrolidinium iodide, an archetypal rotator-phase ionic conductor.

    PubMed

    Adebahr, Josefina; Seeber, Aaron J; MacFarlane, Douglas R; Forsyth, Maria

    2005-11-03

    N,N-Dimethyl-pyrrolidinium iodide, and the effect of doping with LiI, has been investigated using DSC, NMR, and impedance spectroscopy. It was found that the addition of a small amount of LiI enhances the ionic conductivity by up to 3 orders of magnitude for this ionic solid. Furthermore, a slight decrease in phase transition onset temperatures, as well as the appearance of a superimposed narrow line in the (1)H NMR spectra with dopant, suggest that the LiI facilitates the mobility of the matrix material, possibly by the introduction of vacancies within the lattice. (7)Li NMR line width measurements reveal a narrow Li line width, decreasing in width and increasing in intensity with temperature, indicating mobile Li ions.

  5. Understanding the influence of Mg doping for the stabilization of capacity and higher discharge voltage of Li- and Mn-rich cathodes for Li-ion batteries.

    PubMed

    Nayak, Prasant Kumar; Grinblat, Judith; Levi, Elena; Levi, Mikhael; Markovsky, Boris; Aurbach, Doron

    2017-02-22

    Although Li- and Mn-rich layered cathodes exhibit high specific capacity, the cathode materials of the general formula Li1+x[NiyMnzCow]O2 (x + y + z + w = 1) suffer from capacity fading and discharge-voltage decay during prolonged cycling, due to the layered-to-spinel transformation upon cycling to potentials higher than 4.5 V vs. Li. In this paper, we study the effect of Mg doping (by partial replacement of Mn ions) on the electrochemical performance of Li- and Mn-rich cathodes in terms of specific capacity, capacity retention and discharge voltage upon cycling. Mg-doped Li- and Mn-rich Li1.2Ni0.16Mn0.54Mg0.02Co0.08O2 and Li1.2Ni0.16Mn0.51Mg0.05Co0.08O2 cathode materials were synthesized by a self-combustion reaction (SCR), and their electrochemical performance in Li-ion batteries was tested. The replacement of a small amount of Mn ions by Mg ions in these materials results in a decrease in their specific capacity. The doping of a small amount of Mg (x = 0.02) resulted only in the stabilization of the capacity, whereas a greater amount (x = 0.05) resulted in improved capacity retention and discharge voltage upon cycling. Li1.2Ni0.16Mn0.51Mg0.05Co0.08O2 exhibits a low specific capacity of about 160 mA h g(-1), which increases and then stabilizes at about 230 mA h g(-1), and finally decreases to 210 mA h g(-1) during 100 cycles. The substitution of Mg for Mn (x = 0.05) results in a higher discharge voltage than the other two cathode materials examined in this study. Structural analysis of the cycled electrodes suggests that Mg suppresses the activation of Li2MnO3 during the initial cycling, and hence, partially prevents layered-to-spinel transformation, resulting in a better electrochemical performance of the Mg-doped cathode material as compared to the undoped material.

  6. Development of low temperature Li-ion electrolytes for NASA and DoD applications

    NASA Astrophysics Data System (ADS)

    Plichta, E. J.; Hendrickson, M.; Thompson, R.; Au, G.; Behl, W. K.; Smart, M. C.; Ratnakumar, B. V.; Surampudi, S.

    Both NASA and the US Army have interest in developing secondary energy storage devices with improved low temperature performance to meet the demanding requirements of space missions and man-portable applications. Lithium-ion systems have been identified as having the most promise due to their high specific energy density and wide operational temperature ranges from the use of organic solvent-based electrolytes, rather than aqueous-based systems. Initially, the SOA lithium-ion technology was limited to operation above -10°C, due primarilly to the fact that the electrolytes employed had high melting points and were highly viscous at low temperatures, resulting in low ionic conductivity. However, due to recent developments in electrolyte formulations at the Army and at JPL, improved low temperature performance of lithium-ion cells have been demonstrated, with efficient cell operation to temperatures as low as -30°C. This was achieved by developing multi-component solvent systems, based on mixtures of cyclic and aliphatic alkyl carbonates. In the course of investigating the viability of a number of advanced electrolyte systems, it was identified that the protective surface films which form on the carbonaceous-based anodes can strongly influence the low temperature capabilities of lithium-ion cells, in addtion to the ionic conductivity of the electrolyte. Thus, in order to optimize an electrolyte for low temperature applications, it is necessary to balance the inherent physical properties of the formulations (i.e. freezing point, viscosity, and ionic conductivity) with the observed compatibility with the chosen cell chemistry (i.e. the nature of the passivating films formed on the electrodes).

  7. Novel binary deep eutectic electrolytes for rechargeable Li-ion batteries based on mixtures of alkyl sulfonamides and lithium perfluoroalkylsulfonimide salts

    NASA Astrophysics Data System (ADS)

    Geiculescu, O. E.; DesMarteau, D. D.; Creager, S. E.; Haik, O.; Hirshberg, D.; Shilina, Y.; Zinigrad, E.; Levi, M. D.; Aurbach, D.; Halalay, I. C.

    2016-03-01

    Ionic liquids (IL's) were proposed for use in Li-ion batteries (LIBs), in order to mitigate some of the well-known drawbacks of LiPF6/mixed organic carbonates solutions. However, their large cations seriously decrease lithium transference numbers and block lithium insertion sites at electrode-electrolyte interfaces, leading to poor LIB rate performance. Deep eutectic electrolytes (DEEs) (which share some of the advantages of ILs but possess only one cation, Li+), were then proposed, in order to overcome the difficulties associated with ILs. We report herein on the preparation, thermal properties (melting, crystallization, and glass transition temperatures), transport properties (specific conductivity and viscosity) and thermal stability of binary DEEs based on mixtures of lithium bis(trifluoromethane)sulfonimide or lithium bis(fluoro)sulfonimide salts with an alkyl sulfonamide solvent. Promise for LIB applications is demonstrated by chronoamperometry on Al current collectors, and cycling behavior of negative and positive electrodes. Residual current densities of 12 and 45 nA cm-2 were observed at 5 V vs. Li/Li+ on aluminum, 1.5 and 16 nA cm-2 at 4.5 V vs. Li/Li+, respectively for LiFSI and LiTFSI based DEEs. Capacities of 220, 130, and 175 mAh· g-1 were observed at low (C/13 or C/10) rates, respectively for petroleum coke, LiMn1/3Ni1/3Co1/3O2 (a.k.a. NMC 111) and LiAl0.05Co0.15Ni0.8O2 (a.k.a. NCA).

  8. Structure and ferromagnetism in vanadium-doped LiNbO3

    NASA Astrophysics Data System (ADS)

    Sheng, P.; Zeng, F.; Tang, G. S.; Pan, F.; Yan, W. S.; Hu, F. C.

    2012-08-01

    Doping into LiNbO3 (LN) and studying its magnetism might provide an alternative way for fabricating diluted magnetic compounds with potential application in the field of spintronics. Room-temperature ferromagnetic V-doped LN with V contents of 1-3 at. % was prepared by ion-beam implantation. The samples exhibit a maximum atomic magnetic moment of 3.82 μB/V at a V doping concentration of 2 at. %. Structural characterization and first principle calculation suggest that the magnetism most likely arises from the oxygen vacancy around the V dopant. X-ray absorption near-edge spectroscopy reveals that the V atom principally substituted for the Nb atom in the LN lattice and that the V is octahedrally coordinated but with a large distortion. It also showed that oxygen vacancies are present in the third shell of the doped V atoms. With the aid of first-principle calculations, we constructed the electronic structure of this system and demonstrated that the O vacancies play an important role in modulating the magnetism. These O vacancies can release the magnetic moment of the V dopant and enhance spin coupling over a long range. Two O vacancies are estimated to have an atomic magnetic moment of 4 μB, which is consistent with the results of magnetic measurements.

  9. Surface charging at the (1 0 0) surface of Cu doped and undoped Li2B4O7

    NASA Astrophysics Data System (ADS)

    Xiao, Jie; Lozova, N.; Losovyj, Ya. B.; Wooten, D.; Ketsman, I.; Swinney, M. W.; Petrosky, J.; McClory, J.; Burak, Ya. V.; Adamiv, V. T.; Brant, A. T.; Dowben, P. A.

    2011-02-01

    We have compared the photovoltaic charging of the (1 0 0) surface termination for Cu doped and undoped Li2B4O7. While the surface charging at the (1 0 0) surface of Li2B4O7 is significantly greater than observed at (1 1 0) surface, the Cu doping plays a role in reducing the surface photovoltage effects. With Cu doping of Li2B4O7, the surface photovoltaic charging is much diminished at the (1 0 0) surface. The density of states observed with combined photoemission and inverse photoemission remains similar to that observed for the undoped material, except in the vicinity of the conduction band edge.

  10. Lithium ion transport of solid electrolytes based on PEO/CF 3SO 3Li and aluminum carboxylate

    NASA Astrophysics Data System (ADS)

    Zygadło-Monikowska, E.; Florjańczyk, Z.; Rogalska-Jońska, E.; Werbanowska, A.; Tomaszewska, A.; Langwald, N.; Golodnitsky, D.; Peled, E.; Kovarsky, R.; Chung, S. H.; Greenbaum, S. G.

    A homogeneous, composite polymer electrolyte (PE) containing poly(ethylene oxide) (PEO), CF 3SO 3Li and 33 wt.% of aluminum carboxylate [RC(O)OAlEt 2] 2 with an oligooxyethylene group R = CH 2CH 2C(O)O(CH 2CH 2O) nCH 3 (n = 7) (AlCarb7), characterized by low glass transition temperature T g = -51.4 °C was prepared. The interaction of aluminum carboxylate with various lithium salts was characterized on the basis of 27Al NMR spectroscopy in CDCl 3 solutions. The bulk conductivity of solid PE with AlCarb7 is of the order of 10 -5 S cm -1 at 60 °C and 10 -4 S cm -1 at 90 °C. Electrochemical tests of Li|PE|Li cells showed a decrease in the R SEI with temperature, stabilizing at about 10 Ω cm -2. The lithium ion transference numbers determined by ac-dc polarization experiments range from 0.7 to 0.9. 7Li, 19F and 1H NMR spectra, the relaxation time and diffusion data were obtained. The calculated lithium transference number t + at 50 °C is equal to 0.995, which suggests practically complete immobilization of the triflate salt anions. In the range of high temperatures (130-180 °C) t + is equal 0.35-0.39. The dependence of t + on temperature should probably be connected with the partial dissociation of the aluminum carboxylate and lithium salt complex.

  11. An Artificial SEI Enables the Use of A LiNi0.5Mn1.5O4 5 V Cathode with Conventional Electrolytes

    SciTech Connect

    Li, Juchuan; Baggetto, Loic; Martha, Surendra K; Veith, Gabriel M; Nanda, Jagjit; Liang, Chengdu; Dudney, Nancy J

    2013-01-01

    LiNi0.5Mn1.5O4 spinel is considered one of the most promising cathodes for advanced lithium ion batteries. However, the operation potential of LiNi0.5Mn1.5O4, ~4.75 V, is beyond the high voltage limit of the state-of-art electrolyte, ~4.3 V. Here, using thin films of LiNi0.5Mn1.5O4 as a model material, we show evidence that an artificial solid electrolyte interphase (SEI) enables the use of this 5 V cathode with conventional carbonate electrolytes. A thin coating of Lipon (lithium phosphorus oxynitride) as an artificial SEI on LiNi0.5Mn1.5O4 could remedy the decomposition of the electrolyte. The thickness of the Lipon artificial SEI is optimized by balancing the protection and additional resistance. The strategy of artificial SEI on cathodes is expected to enable the wide application of other high voltage cathodes for lithium ion batteries.

  12. Direct Growth of Bismuth Film as Anode for Aqueous Rechargeable Batteries in LiOH, NaOH and KOH Electrolytes

    PubMed Central

    Zuo, Wenhua; Xu, Pan; Li, Yuanyuan; Liu, Jinping

    2015-01-01

    As promising candidates for next-generation energy storage devices, aqueous rechargeable batteries are safer and cheaper than organic Li ion batteries. But due to the narrow voltage window of aqueous electrolytes, proper anode materials with low redox potential and high capacity are quite rare. In this work, bismuth electrode film was directly grown by a facile hydrothermal route and tested in LiOH, NaOH and KOH electrolytes. With low redox potential (reduction/oxidation potentials at ca. −0.85/−0.52 V vs. SCE, respectively) and high specific capacity (170 mAh·g−1 at current density of 0.5 A·g−1 in KOH electrolyte), Bi was demonstrated as a suitable anode material for aqueous batteries. Furthermore, by electrochemical impedance spectroscopy (EIS) analysis, we found that with smaller Rs and faster ion diffusion coefficient, Bi electrode film in KOH electrolyte exhibited better electrochemical performance than in LiOH and NaOH electrolytes.

  13. How To Improve Capacity and Cycling Stability for Next Generation Li-O2 Batteries: Approach with a Solid Electrolyte and Elevated Redox Mediator Concentrations.

    PubMed

    Bergner, Benjamin J; Busche, Martin R; Pinedo, Ricardo; Berkes, Balázs B; Schröder, Daniel; Janek, Jürgen

    2016-03-01

    Because of their exceptionally high specific energy, aprotic lithium oxygen (Li-O2) batteries are considered as potential future energy stores. Their practical application is, however, still hindered by the high charging overvoltages and detrimental side reactions. Recently, the use of redox mediators dissolved in the electrolyte emerged as a promising tool to enable charging at moderate voltages. The presented work advances this concept and distinctly improves capacity and cycling stability of Li-O2 batteries by combining high redox mediator concentrations with a solid electrolyte (SE). The use of high redox mediator concentrations significantly increases the discharge capacity by including the oxidation and reduction of the redox mediator into charge cycling. Highly efficient cycling is achieved by protecting the lithium anode with a solid electrolyte, which completely inhibits unfavored deactivation of oxidized species at the anode. Surprisingly, the SE also suppresses detrimental side reactions at the carbon electrode to a large extent and enables stable charging completely below 4.0 V over a prolonged period. It is demonstrated that anode and cathode communicate deleteriously via the liquid electrolyte, which induces degradation reactions at the carbon electrode. The separation of cathode and anode with a SE is therefore considered as a key step toward stable Li-O2 batteries, in conjunction with a concentrated redox mediator electrolyte.

  14. Enhanced ionic conductivity of apatite-type lanthanum silicate electrolyte for IT-SOFCs through copper doping

    NASA Astrophysics Data System (ADS)

    Ding, Xifeng; Hua, Guixiang; Ding, Dong; Zhu, Wenliang; Wang, Hongjin

    2016-02-01

    Apatite-type Lanthanum silicate (LSO) is among the most promising electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs) owing to the high conductivity and low activation energy at lower temperature than traditional doped-zirconia electrolyte. The ionic conductivity as well as the sintering density of lanthanum silicate oxy-apatite, La10Si6-xCuxO27-δ (LSCO, 0 ≤ x ≤ 2), was effectively enhanced through a small amount of doped copper. The phase composition, relative density, ionic conductivity and thermal expansion behavior of La10Si6-xCuxO27-δ was systematically investigated by X-ray diffraction (XRD), Archimedes' drainage method, scanning electron microscope (SEM), electrochemical impedance spectra (EIS) and thermal dilatometer techniques. With increasing copper doping content, the ionic conductivity of La10Si6-xCuxO27-δincreased, reaching a maximum of 4.8 × 10-2 S cm-1 at 800 °C for x = 1.5. The improved ionic conductivity could be primarily associated with the enhanced grain conductivity. The power output performance of NiO-LSCO/LSCO/LSCF single cell was superior to that obtained on NiO-LSO/LSO/LSCF at different temperatures using hydrogen as fuel and oxygen as oxidant, which could be attributed to the enhanced oxygen ionic conductivity as well as the sintering density for the copped doped lanthanum silicate. In conclusion, the apatite La10Si4.5Cu1.5O25.5 is a promising candidate electrolyte for IT-SOFCs.

  15. Oligo(ethylene glycol)-functionalized disiloxanes as electrolytes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengcheng; Dong, Jian; West, Robert; Amine, Khalil

    Functionalized disiloxane compounds were synthesized by attaching oligo(ethylene glycol) chains, -(CH 2CH 2O)- n, n = 2-7, via hydrosilation, dehydrocoupling, and nucleophilic substitution reactions and were examined as non-aqueous electrolyte solvents in lithium-ion cells. The compounds were fully characterized by 1H, 13C, and 29Si nuclear magnetic resonance (NMR) spectroscopy. Upon doping with lithium bis(oxalato)borate (LiBOB) or LiPF 6, the disiloxane electrolytes showed conductivities up to 6.2 × 10 -4 S cm -1 at room temperature. The thermal behavior of the electrolytes was studied by differential scanning calorimetry, which revealed very low glass transition temperatures before and after LiBOB doping and much higher thermal stability compared to organic carbonate electrolytes. Cyclic voltammetry measurements showed that disiloxane-based electrolytes with 0.8 M LiBOB salt concentration are stable to 4.7 V. The LiBOB/disiloxane combinations were found to be good electrolytes for lithium-ion cells; unlike LiPF 6, LiBOB can provide a good passivation film on the graphite anode. The LiPF 6/disiloxane electrolyte was enabled in lithium-ion cells by adding 1 wt% vinyl ethylene carbonate (VEC). Full cell performance tests with LiNi 0.80Co 0.15Al 0.05O 2 as the cathode and mesocarbon microbead (MCMB) graphite as the anode show stable cyclability. The results demonstrate that disiloxane-based electrolytes have considerable potential as electrolytes for use in lithium-ion batteries.

  16. Nanostructured all-solid-state supercapacitor based on Li2S-P2S5 glass-ceramic electrolyte

    NASA Astrophysics Data System (ADS)

    Francisco, Brian E.; Jones, Christina M.; Lee, Se-Hee; Stoldt, Conrad R.

    2012-03-01

    While today's lithium-ion batteries offer acceptable energy storage capability, they lack the ability to be cycled repeatedly more than a couple thousand times. Electrochemical capacitors, i.e., supercapacitors, are being developed whose lifetimes exceed 1 × 106 cycles and power densities surpass those of batteries by several times. Here, we present an all-solid-state supercapacitor using a Li2S-P2S5 glass-ceramic electrolyte as both separator and ion conductor. Three device architectures are examined including two with nanostructured electrodes which incorporate multi-walled carbon nanotubes (MWCNTs). Cyclic voltammograms and electrochemical impedance measurements demonstrate that these devices develop reversible double layer capacitance, and a maximum of 7.75 F/g is achieved in the device constructed by mechanically mixing the nanostructured electrodes. Electrochemical impedance spectroscopy explains non-idealities observed when MWCNTs are incorporated in the electrode layers.

  17. Performance of electrical double layer capacitors fabricated with gel polymer electrolytes containing Li+ and K+-salts: A comparison

    NASA Astrophysics Data System (ADS)

    Singh, Manoj K.; Hashmi, S. A.

    2015-06-01

    The comparative performance of the solid-state electrical double layer capacitors (EDLCs) based on the multiwalled carbon nanotube (MWCNT) electrodes and poly (vinaylidinefluoride-co-hexafluoropropyline) (PVdF-HFP) based gel polymer electrolytes (GPEs) containing potassium and lithium salts have been studied. The room temperature ionic conductivity of the GPEs have been found to be ˜3.8×10-3 and 5.9×10-3 S cm-1 for lithium and potassium based systems. The performance of EDLC cells studied by impedance spectroscopy, cyclic voltammetry and constant current charge-discharge techniques, indicate that the EDLC with potassium salt containing GPE shows excellent performance almost equivalent to the EDLC with Li-salt-based GPE.

  18. Successes and failures of Hubbard-corrected density functional theory. The case of Mg doped LiCoO2

    DOE PAGES

    Santana Palacio, Juan A.; Kim, Jeongnim; Kent, Paul R.; ...

    2014-10-28

    We have evaluated the successes and failures of the Hubbard-corrected density functional theory approach to study Mg doping of LiCoO2. We computed the effect of the U parameter on the energetic, geometric, and electronic properties of two possible doping mechanisms: (1) substitution of Mg onto a Co (or Li) site with an associated impurity state and (2) formation of impurity-state-free complexes of substitutional Mg and point defects in LiCoO2. We find that formation of impurity states results in changes on the valency of Co in LiCoO2. Variation of the Co U shifts the energy of the impurity state, resulting inmore » energetic, geometric, and electronic properties that depend significantly on the specific value of U. In contrast, the properties of the impurity-state-free complexes are insensitive to U. These results identify reasons for the strong dependence on the doping properties on the chosen value of U and for the overall difficulty of achieving agreement with the experimentally known energetic and electronic properties of doped transition metal oxides such as LiCoO2.« less

  19. Electrical properties of undoped and Li-doped NiO thin films deposited by RF sputtering without intentional heating

    NASA Astrophysics Data System (ADS)

    Sugiyama, Mutsumi; Nakai, Hiroshi; Sugimoto, Gaku; Yamada, Aika; Chichibu, Shigefusa F.

    2016-08-01

    The fundamental transmittance and electrical properties of undoped and Li-doped NiO thin films deposited by conventional RF sputtering without intentional heating were evaluated. Both the transmittance and resistivity of undoped and Li-doped NiO decreased with increasing O2 fraction in the sputtering gas, f(O2) = O2/(Ar + O2). The result is attributed to the increase in the concentration of acceptors of Ni vacancies (VNi) under oxygen-rich growth conditions. In addition to VNi, Li atom on the Ni site (LiNi) likely acts as a shallow accepter, which can explain the experimental finding that the carrier concentration of Li-doped NiO was approximately three orders of magnitude higher than that of the undoped case deposited under the same f(O2). The mobility of NiO was remarkably low (around 0.1-1.0 cm2 V-1 s-1) and almost independent of f(O2) or the amount of doping, reflecting the large hole effective mass.

  20. Li-O(2) battery based on highly efficient Sb-doped tin oxide supported Ru nanoparticles.

    PubMed

    Li, Fujun; Tang, Dai-Ming; Jian, Zelang; Liu, Dequan; Golberg, Dmitri; Yamada, Atsuo; Zhou, Haoshen

    2014-07-16

    Novel cathodes based on Sb-doped tin oxide (STO)-supported Ru particles enable Li-O2 batteries to be operated below 4.0 V, which is of crucial importance for the realization of rechargeable Li-O2 batteries, and to deliver a high specific capacity of 750 mA h g(-1) even after 50 discharge-charge cycles at 0.1 mA cm(-2) .

  1. Electrochemical Analysis for Enhancing Interface Layer of Spinel Li4Ti5O12: p-Toluenesulfonyl Isocyanate as Electrolyte Additive.

    PubMed

    Wang, Ren-Heng; Li, Xin-Hai; Wang, Zhi-Xing; Guo, Hua-Jun; He, Zhen-Jiang

    2015-10-28

    An electrolyte additive, p-toluenesulfonyl isocyanate (PTSI), is evaluated in our work to overcome the poor cycling performance of spinel lithium titanate (Li4Ti5O12) lithium-ion batteries. We find that the cycling performance of a Li/Li4Ti5O12 cell with 0.5 wt % PTSI after 400 cycles is obviously improved. Remarkably, we also find that a solid electrolyte interface (SEI) film is formed about 1.2 V, which has higher potential to generate a stable SEI film than do carbonate solvents in the voltage range of 3.0-0 V. The stable SEI film derived from PTSI can effectively suppress the decomposition of electrolyte, HF generation, interfacial reaction, and LiF formation upon cycling. These observations are explained in terms of PTSI including SO3. The S═O groups can delocalize the nitrogen core, which acts as the weak base site to hinder the reactivity of PF5. Hence, HF generation and LiF formation are suppressed.

  2. Physical properties of high Li-ion content N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide based ionic liquid electrolytes.

    PubMed

    Yoon, Hyungook; Best, Adam S; Forsyth, Maria; MacFarlane, Douglas R; Howlett, Patrick C

    2015-02-14

    Electrolytes based on bis(fluorosulfonyl)imide (FSI) with a range of LiFSI salt concentrations were characterized using physical property measurements, as well as NMR, FT-IR and Raman spectroscopy. Different from the behavior at lower concentrations, the FSI electrolyte containing 1 : 1 salt to IL mole ratio showed less deviation from the KCl line in the Walden plot, suggesting greater ionic dissociation. Diffusion measurements show higher mobility of lithium ions compared to the other ions, which suggests that the partial conductivity of Li(+) is higher at this higher composition. Changes in the FT-IR and Raman peaks indicate that the cis-FSI conformation is preferred with increasing Li salt concentration.

  3. Depth profiling the solid electrolyte interphase on lithium titanate (Li4Ti5O12) using synchrotron-based photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Nordh, Tim; Younesi, Reza; Brandell, Daniel; Edström, Kristina

    2015-10-01

    The presence of a surface layer on lithium titanate (Li4Ti5O12, LTO) anodes, which has been a topic of debate in scientific literature, is here investigated with tunable high surface sensitive synchrotron-based photoelectron spectroscopy (PES) to obtain a reliable depth profile of the interphase. Li||LTO cells with electrolytes consisting of 1 M lithium hexafluorophosphate dissolved in ethylene carbonate:diethyl carbonate (LiPF6 in EC:DEC) were cycled in two different voltage windows of 1.0-2.0 V and 1.4-2.0 V. LTO electrodes were characterized after 5 and 100 cycles. Also the pristine electrode as such, and an electrode soaked in the electrolyte were analyzed by varying the photon energies enabling depth profiling of the outermost surface layer. The main components of the surface layer were found to be ethers, P-O containing compounds, and lithium fluoride.

  4. White upconversion emission in Li+/Yb3+/Tm3+/Er3+-doped Gd6MoO12 phosphors

    NASA Astrophysics Data System (ADS)

    Sun, Jiayue; Xue, Bing; Du, Haiyan

    2013-07-01

    The Yb3+/Er3+/Tm3+-doped Gd6MoO12 phosphors and Li+/Yb3+/Er3+/Tm3+-doped Gd6MoO12 phosphors were synthesized by the high-temperature solid-state method. Under 980 nm laser diode excitation, the Gd6MoO12:Li+/Yb3+/Er3+/Tm3+ phosphors show the white upconversion (UC) emission at the pump power of 200 mW/cm2, which is composed of the blue (1G4→3H6 of Tm3+), green (2H11/2, 4S3/2→4I15/2 of Er3+), and red (4F9/2→4I15/2 of Er3+) UC emissions. The calculated CIE color coordinates of Gd6MoO12:Tm3+/Er3+/Yb3+ phosphors changed from blue area to white area after the Li+ ion doping. Then, the effect of Li+ ions mixing on the emission was analysed. The relative UC mechanisms and properties were also investigated and proposed based on their spectral. The additional mixed Li+ ions enhanced the red and green upconversion emission largely in this phosphor and then formed the white UC emission, which indicated that the Li+ is a promising dopant for tuning white light luminescence in some case.

  5. Activated carbon and single-walled carbon nanotube based electrochemical capacitor in 1 M LiPF{sub 6} electrolyte

    SciTech Connect

    Azam, M.A.; Jantan, N.H.; Dorah, N.; Seman, R.N.A.R.; Manaf, N.S.A.; Kudin, T.I.T.; Yahya, M.Z.A.

    2015-09-15

    Highlights: • Activated carbon and single-walled CNT based electrochemical capacitor. • Electrochemical analysis by means of CV, charge/discharge and impedance. • 1 M LiPF{sub 6} non-aqueous solution as an electrolyte. • AC/SWCNT electrode exhibits a maximum capacitance of 60.97 F g{sup −1}. - Abstract: Carbon nanotubes have been extensively studied because of their wide range of potential application such as in nanoscale electric circuits, textiles, transportation, health, and the environment. Carbon nanotubes feature extraordinary properties, such as electrical conductivities higher than those of copper, hardness and thermal conductivity higher than those of diamond, and strength surpassing that of steel, among others. This research focuses on the fabrication of an energy storage device, namely, an electrochemical capacitor, by using carbon materials, i.e., activated carbon and single-walled carbon nanotubes, of a specific weight ratio as electrode materials. The electrolyte functioning as an ion carrier is 1 M lithium hexafluorophosphate. Variations in the electrochemical performance of the device, including its capacitance, charge/discharge characteristics, and impedance, are reported in this paper. The electrode proposed in this work exhibits a maximum capacitance of 60.97 F g{sup −1} at a scan rate of 1 mV s{sup −1}.

  6. Photocatalytic activity of Li-doped TiO{sub 2} nanoparticles: Synthesis via ionic liquid-assisted hydrothermal route

    SciTech Connect

    Ravishankar, T.N.; Nagaraju, G.; Dupont, Jairton

    2016-06-15

    Highlights: • TiO{sub 2}: Li nanoparticles were synthesized via an ionic liquid-assisted hydrothermal method. • The doping of Li to anatase TiO{sub 2} affects the properties of the resultant product. • TiO{sub 2}: Li nanoparticles were used as a photocatalyst for the degradation of dye. • TiO{sub 2}: Li nanoparticles were used as sensor, and antibacterial agent. • TiO{sub 2}: Li were used as reducing agent for the reduction of Cr{sup 6+} to Cr{sup 3+}. - Abstract: We have proposed a simple one pot synthesis of lithium-doped TiO{sub 2} nanoparticles (TiO{sub 2}:Li) via an ionic liquid-assisted hydrothermal method and their potential use as a photocatalyst for the degradation of organic dye, as well as the reduction of toxic Cr{sup 6+} to non toxic Cr{sup 3+}. The structure of TiO{sub 2}:Li nanoparticles was examined by XRD, FTIR, XPS, Raman, UV–vis, Photoluminescence spectroscopy and morphology by SEM and TEM. The incorporation of Li into anatase-phase TiO{sub 2} affected the optical properties of the resultant TiO{sub 2} nanoparticles. The photocatalytic activity of the TiO{sub 2}:Li nanoparticles was determined by degradation of trypan blue. Degradation studies showed improved photocatalytic activity of TiO{sub 2}:Li nanoparticles compared to TiO{sub 2} nanoparticles and bulk TiO{sub 2}. TiO{sub 2}:Li nanoparticles also functioned as a detoxification agent which was confirmed by the reduction of Cr{sup 6+} to Cr{sup 3+}.

  7. Electrochemical Performance of LiNi0.5Mn1.5O4 by Sol-gel Self-combustion Reaction Method in Different Kinds of Electrolyte for High-voltage Rechargeable Lithium Cells

    NASA Astrophysics Data System (ADS)

    Liang, Xinghua; Shi, Lin; Liu, Yusi; Zeng, Shuaibo; Ye, Chaochao

    2015-07-01

    LiNi0.5Mn1.5O4 cathode material was synthesized through sol-gel self-combustion reaction method. LiNi0.5Mn1.5O4 powders were subsequently characterized as cathode materials in a Li-ion coin cell comprising a Li anode with electrolyte A or electrolyte B. 1.0 mol/L Lithium Hexafluorophosphate (LiPF6) dissolved in volume ration of ethylene carbonate (EC) to ethyl methyl carbonate (EMC) to diethyl carbonate (DEC) corresponded to 4:3:3as electrolyte A, 1.0 mol/L LiPF6 dissolved in volume ration of EC to EMC to DEC corresponded to 4:2:4 as electrolyte B. Electrochemical performance of lithium cells was evaluated. These tests showed that no matter the cells with electrolyte A or electrolyte B has good discharge platform in 4.7V range (3.5V-4.75V) at the rate of 0.1C, the initial discharge capacity of cell with electrolyte B was higher than that with electrolyte A.

  8. Improved Electrochemical Performance of LiFePO4@N-Doped Carbon Nanocomposites Using Polybenzoxazine as Nitrogen and Carbon Sources.

    PubMed

    Wang, Ping; Zhang, Geng; Li, Zhichen; Sheng, Wangjian; Zhang, Yichi; Gu, Jiangjiang; Zheng, Xinsheng; Cao, Feifei

    2016-10-03

    Polybenzoxazine is used as a novel carbon and nitrogen source for coating LiFePO4 to obtain LiFePO4@nitrogen-doped carbon (LFP@NC) nanocomposites. The nitrogen-doped graphene-like carbon that is in situ coated on nanometer-sized LiFePO4 particles can effectively enhance the electrical conductivity and provide fast Li(+) transport paths. When used as a cathode material for lithium-ion batteries, the LFP@NC nanocomposite (88.4 wt % of LiFePO4) exhibits a favorable rate performance and stable cycling performance.

  9. Creation of domains by direct electron beam writing in magnesium-doped LiNbO3 and LiNbO3:Fe single crystals

    NASA Astrophysics Data System (ADS)

    Palatnikov, M. N.; Kokhanchik, L. S.; Emelin, E. V.; Sidorov, N. V.; Manukovskaya, D. V.

    2016-03-01

    Domain structures in the Z-cut of highly doped LiNbO3:Mg and LiNbO3:Mg,Fe single crystals were created by direct electron beam writing (DEBW). It was found that the value and type of electron conductivity influence the shape and number of domains thus created. Controlled electron beam regular domains were created only in samples of the crystal LiNbO3:Mg,Fe [MgO] = 5.16 mol.%, [Fe] = 0.007 mol.%. In highly doped LiNbO3:Mg ([MgO] = 5.19 mol.%) crystal, the domains were formed chaotically and controlled creation of domains did not occur. The domain shapes were analyzed in the framework of the theory of screening of domain nuclei depolarizing electric fields and the influence of screening on the final shape of domains. It was found that screening of intrinsic electric fields is faster in the LiNbO3:Mg,Fe crystal. This crystal has a high electronic conductivity of hopping type with a high mobility of charge carriers. Thus, a small amount of Fe provides equilibrium between the ferroelectric switching velocity and screening of the depolarizing electric field velocity. The results are discussed considering differences in the electron conductivity mechanisms, which control the screening of depolarizing electric field velocity and spatial charge area formed under an electron beam.

  10. Simultaneous size and luminescence control of NaYF4:Yb3+/RE3+ (RE = Tm, Ho) microcrystals via Li+ doping

    NASA Astrophysics Data System (ADS)

    Lin, Hao; Xu, Dekang; Teng, Dongdong; Yang, Shenghong; Zhang, Yueli

    2015-07-01

    Enhancement of upconversion (UC) luminescence is imperative for the applications of UC microcrystals (MCs). In this work, NaYF4:Yb3+/RE3+ (RE = Tm, Ho) MCs via Li+ doping were successfully prepared by a simple hydrothermal process with the assistance of citric acid. The UC luminescence intensities of NaYF4:Yb3+/RE3+ (RE = Tm, Ho) are significantly enhanced via Li+ doping at different concentrations. Compared to Li+-absent sample, UC luminescence intensities of blue emission (477 nm) and red emission (649 nm) in NaYF4:Yb3+/Tm3+ MCs via 15 mol% Li+ doping are improved by 10 and 9 times, respectively; UC luminescence intensities of green emission (538 nm) and red emission (644 nm) in NaYF4:Yb3+/Ho3+ MCs via 15 mol% Li+ doping are improved by 12 and 3 times, respectively. The mechanism of the enhancement via Li+ doping is discussed in details, which may be attributed to the fact that Li+ doping can cause the distortion of the local symmetry around RE ions. Our results indicate that the enhanced UC luminescence of NaYF4:Yb3+/RE3+ (RE = Tm, Ho) MCs via Li+ doping may have potential applications in optoelectronic devices such as solar cells and plasma display panel.

  11. The effect of 0.025 Al-doped in Li4Ti5O12 material on the performance of half cell lithium ion battery

    NASA Astrophysics Data System (ADS)

    Priyono, Slamet; Triwibowo, Joko; Prihandoko, Bambang

    2016-02-01

    The effect of 0.025 Al-doped Li4Ti5O12 as anode material for Lithium Ion battery had been studied. The pure and 0.025 Al-doped Li4Ti5O12 were synthesized through solid state process in air atmosphere. Physical characteristics of all samples were observed by XRD, FTIR, and PSA. The XRD analysis revealed that the obtained particle was highly crystalline and had a face-centered cubic spinel structure. The XRD pattern also showed that the 0.025 Al-doped on the Li4Ti5O12 did not change crystal structure of Li4Ti5O12. FTIR analysis confirmed that the spinel structure in fingerprint region was unchanged when the structure was doped by 0.025 Al. However the doping of 0.025 Al increased particle size significantly. The electrochemical performance was studied by using cyclic voltammetry (CV) and charge-discharge (CD) curves. Electrochemical analysis showed that pure Li4Ti5O12 has higher capacity than 0.025 Al-doped Li4Ti5O12 had. But 0.025 Al-doped Li4Ti5O12 possesses a better cycling stability than pure Li4Ti5O12.

  12. Enhanced Quantum Cutting via Li(+) Doping from a Bi(3+)/Yb(3+)-Codoped Gadolinium Tungstate Phosphor.

    PubMed

    Yadav, Ran Vijay; Yadav, Ram Sagar; Bahadur, Amresh; Singh, Akhilesh Kumar; Rai, Shyam Bahadur

    2016-11-07

    The Bi(3+)/Yb(3+)-codoped gadolinium tungstate phosphor has been synthesized through a solid-state reaction method. The structural characterization reveals the crystalline nature of the phosphor. The Bi(3+)-doped phosphor emits visible radiation from the blue to red regions upon excitation with 330 and 355 nm. The addition of Yb(3+) to the Bi(3+)-doped phosphor reduces the emission intensity in the visible region and emits an intense near-infrared (NIR) photon centered at 976 nm through a quantum-cutting (QC) phenomenon. This is due to cooperative energy transfer (CET) from the (3)P1 level of Bi(3+) to the (2)F5/2 level of Yb(3+). The presence of Li(+) ions in the Bi(3+)/Yb(3+)-codoped phosphor enhances the emission intensity in the NIR region up to by 3 times, whereas the emission intensity in the visible region is significantly reduced. The energy transfer (ET) from the Bi(3+) ions to the Yb(3+) ions is confirmed by lifetime measurements, and the lifetime for the (3)P1 level of Bi(3+) decreases continuously with increasing Yb(3+) concentration. The ET efficiency (ηETE) and corresponding QC efficiency (ηQE) are calculated and found to be 29% and 129%, respectively. The presence of Li(+) enhances the QC efficiency of the phosphor up to 43%. Thus, the Bi(3+)/Yb(3+)/Li(+)-codoped phosphor is a promising candidate to enhance the efficiency of a crystalline-silicon-based solar cell through spectral conversion.

  13. Quercetin as electrolyte additive for LiNi0.5Mn1.5O4 cathode for lithium-ion secondary battery at elevated temperature

    NASA Astrophysics Data System (ADS)

    Kim, Sungkyung; Kim, Myeongho; Choi, Insoo; Kim, Jae Jeong

    2016-12-01

    In an attempt to ameliorate the poor cyclability of LiNi0.5Mn1.5O4 at elevated temperature, quercetin is applied as an additive. The irreversible oxidative behavior of quercetin is thoroughly investigated by electrochemical method. The improved cyclability of the quercetin-containing cell at high temperature implies that by forming robust and less-resistive SEI, quercetin is preferentially oxidized and passivates the LiNi0.5Mn1.5O4 electrode. EIS result coherently suggests that the quercetin-added electrolyte forms a more compact and Li-ion conducting interface. The surface sensitive XPS analysis confirms that the presence of quercetin restrains the formation of LiF, suppresses the reaction of PF5, and alleviates Mn dissolution. Meanwhile, ICP-MS analysis affirms the effectiveness of quercetin against Mn dissolution. The self-discharge experiment which exhibits the retained charged state of LiNi0.5Mn1.5O4 at high temperature, gives convincing evidence of the effect of quercetin. Intensive analyses confirm that quercetin can effectively prolong the cycle-life of LiNi0.5Mn1.5O4 at elevated temperature. We envision its potential and practical usage as an electrolyte additive for high-voltage cathode.

  14. Cation Mixing Properties toward Co Diffusion at the LiCoO2 Cathode/Sulfide Electrolyte Interface in a Solid-State Battery.

    PubMed

    Haruyama, Jun; Sodeyama, Keitaro; Tateyama, Yoshitaka

    2017-01-11

    All-solid-state Li-ion batteries (ASS-LIBs) are expected to be the next-generation battery, however, their large interfacial resistance hinders their widespread application. To understand and resolve the possible causes of this resistance, we examined mutual diffusion properties of the cation elements at LiCoO2 (LCO) cathode/β-Li3PS4 (LPS) solid electrolyte interface as a representative system as well as the effect of a LiNbO3 buffer layer by first-principles calculations. Evaluating energies of exchanging ions between the cathode and the electrolyte, we found that the mixing of Co and P is energetically preferable to the unmixed states at the LCO/LPS interface. We also demonstrated that the interposition of the buffer layer suppresses such mixing because the exchange of Co and Nb is energetically unfavorable. Detailed analyses of the defect levels and the exchange energies by using the individual bulk crystals as well as the interfaces suggest that the lower interfacial states in the energy gap can make a major contribution to the stabilization of the Co ↔ P exchange, although the anion bonding preference of Co and P as well as the electrostatic interactions may have effects as well. Finally, the Co ↔ P exchanges induce interfacial Li sites with low chemical potentials, which enhance the growth of the Li depletion layer. These atomistic understandings can be meaningful for the development of ASS-LIBs with smaller interfacial resistances.

  15. Preparation of V-Doped LiFePO4/C as the Optimized Cathode Material for Lithium Ion Batteries.

    PubMed

    Sun, Pingping; Zhang, Haiyang; Shen, Kai; Fan, Qi; Xu, Qingyu

    2015-04-01

    LiFe1-x,Vx,PO4/C composites were synthesized by solid state reaction. The effect of carbon coating and V doping on the performance of LiFePO4 has been systematically investigated by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), charge/discharge and cyclic voltammetry (CV) measurement. The results show that carbon coating and proper amount of V incorporation do not significantly change the host crystal structure of LiFePO4, while the electrochemical performance of LiFePO4 can be significantly improved. Particularly, the LiFe0.96V0.04PO4/C exhibits the best performance with a specific discharge capacity of 105.5 mA h/g at 5.0 C, 90.3 mA h/g at 10 C and 66.7 mA h/g at 30 C with stable cycle performance, which is significantly improved compared with the pure LiFePO4/C. The cyclic voltammograms result reveals that V doping could decrease the resistance of LiFePO4/C composite electrode drastically and improve its reversibility.

  16. Pyrolysis result of polyethylene waste as fuel for solid oxide fuel cell with samarium doped-ceria (SDC)-carbonate as electrolyte

    NASA Astrophysics Data System (ADS)

    Syahputra, R. J. E.; Rahmawati, F.; Prameswari, A. P.; Saktian, R.

    2017-02-01

    In this research, the result of pyrolysis on polyethylene was used as fuel for a solid oxide fuel cell (SOFC). The pyrolysis result is a liquid which consists of hydrocarbon chains. According to GC-MS analysis, the hydrocarbons mainly consist of C7 to C20 hydrocarbon chain. Then, the liquid was applied to a single cell of NSDC-L | NSDC | NSDC-L. NSDC is a composite SDC (samarium doped-ceria) with sodium carbonate. Meanwhile, NSDC-L is a composite of NSDC with LiNiCuO (LNC). NSDC and LNC were analyzed by X-ray diffraction to understand their crystal structure. The result shows that presence of carbonate did not change the crystal structure of SDC. SEM EDX analysis for fuel cell before and after being loaded with polyethylene oil to get information of element diffusion to the electrolyte. Meanwhile, the conductivity properties were investigated through impedance measurement. The presence of carbonate even increases the electrical conductivity. The single cell test with the pyrolysis result of polyethylene at 300 – 600 °C, found that the highest power density is at 600 °C with the maximum power density of 0.14 mW/cm2 and open circuit voltage of 0.4 Volt. Elemental analysis at three point spots of single cell NDSC-L |NSDC|NSDC-L found that a migration of ions was occurred during fuel operation at 300 – 600 °C.

  17. Sol-Gel-Derived Lithium Superionic Conductor Li1.5Al0.5Ge1.5(PO4)3 Electrolyte for Solid-State Lithium-Oxygen Batteries

    DTIC Science & Technology

    2014-03-12

    AFRL-RQ-WP-TP-2015-0055 SOL-GEL-DERIVED LITHIUM SUPERIONIC CONDUCTOR LI1.5AL0.5GE1.5(PO4)3 ELECTROLYTE FOR SOLID -STATE LITHIUM -OXYGEN...2014 4. TITLE AND SUBTITLE SOL-GEL-DERIVED LITHIUM SUPERIONIC CONDUCTOR LI1.5AL0.5GE1.5(PO4)3 ELECTROLYTE FOR SOLID -STATE LITHIUM -OXYGEN BATTERIES...attracting a great deal of attention as a solid electrolyte for lithium -oxygen (Li- O2) batteries due to its high ionic conductivity. In this study, LAGP

  18. Optical properties of MgO doped near-stoichiometric LiTaO 3 single crystals

    NASA Astrophysics Data System (ADS)

    Hu, Pengchao; Zhang, Lianhan; Xiong, Jing; Yin, Jigang; Zhao, Chengchun; He, Xiaoming; Hang, Yin

    2011-09-01

    Comparative study of the optical properties of undoped and 1-3 mol% MgO doped near-stoichiometric LiTaO 3 (SLT) crystals were undertaken. It was observed that the red shift in the absorption edge occurred with the increasing MgO doping concentration. The infrared absorption spectrum of the OH-stretch-mode in SLT was measured for crystals of undoped and 1-3 mol% MgO doped compositions. The coercive field for the crystals was measured to be 0.913, 0.610 and 0.735 kV/mm for 1-3 mol% MgO doped SLT, respectively. Photorefractive damage of SLT single crystals with 1-3 mol% MgO doping levels was measured to be 136.29, 180.25 and 222.54 MW/cm 2.

  19. Study of a Li-air battery having an electrolyte solution formed by a mixture of an ether-based aprotic solvent and an ionic liquid

    NASA Astrophysics Data System (ADS)

    Cecchetto, Laura; Salomon, Mark; Scrosati, Bruno; Croce, Fausto

    2012-09-01

    Recent studies have clearly demonstrated that cyclic and linear carbonates are unstable when used in rechargeable Li-air batteries employing aprotic solvents mostly due to the cathodic formation of superoxide during the oxygen reduction reaction. In particular, it has been ascertained that nucleophilic attack by superoxide anion radical, O2-rad , at O-alkyl carbon is a common mechanism of decomposition of organic carbonates. Moreover, theoretical calculations showed that ether chemical functionalities are stable against nucleophilic substitution induced by superoxide. Aim of this study is to report on a new electrolyte solution for Li-air battery formed by a mixture of an ether-based aprotic solvent with an ionic liquid (IL). The IL-based electrolyte was obtained by mixing the pure ionic liquid N-methyl-(n-butyl) pyrrolidinium bis(trifluoromethane sulfonyl) imide (here denoted as PYR14TFSI) to a 0.91 M solution of lithium triflate (LiCF3SO3) in tetra ethylene glycol dimethyl etcher (TEGDME). We observed that the presence of IL beneficially affects the kinetics and the reversibility of the oxygen reactions involved at the cathode. The most significant result being a lower overvoltage for the charge reaction, compared to a Li/air cell containing the same electrolyte solution without IL.

  20. X-ray absorption spectroscopy of LiBF 4 in propylene carbonate. A model lithium ion battery electrolyte

    SciTech Connect

    Smith, Jacob W.; Lam, Royce K.; Sheardy, Alex T.; Shih, Orion; Rizzuto, Anthony M.; Borodin, Oleg; Harris, Stephen J.; Prendergast, David; Saykally, Richard J.

    2014-08-20

    Since their introduction into the commercial marketplace in 1991, lithium ion batteries have become increasingly ubiquitous in portable technology. Nevertheless, improvements to existing battery technology are necessary to expand their utility for larger-scale applications, such as electric vehicles. Advances may be realized from improvements to the liquid electrolyte; however, current understanding of the liquid structure and properties remains incomplete. X-ray absorption spectroscopy of solutions of LiBF4 in propylene carbonate (PC), interpreted using first-principles electronic structure calculations within the eXcited electron and Core Hole (XCH) approximation, yields new insight into the solvation structure of the Li+ ion in this model electrolyte. By generating linear combinations of the computed spectra of Li+-associating and free PC molecules and comparing to the experimental spectrum, we find a Li+–solvent interaction number of 4.5. This result suggests that computational models of lithium ion battery electrolytes should move beyond tetrahedral coordination structures.

  1. Enabling LiTFSI-based electrolytes for safer lithium-ion batteries by using linear fluorinated carbonates as (Co)solvent.

    PubMed

    Kalhoff, Julian; Bresser, Dominic; Bolloli, Marco; Alloin, Fannie; Sanchez, Jean-Yves; Passerini, Stefano

    2014-10-01

    In this Full Paper we show that the use of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as conducting salt in commercial lithium-ion batteries is made possible by introducing fluorinated linear carbonates as electrolyte (co)solvents. Electrolyte compositions based on LiTFSI and fluorinated carbonates were characterized regarding their ionic conductivity and electrochemical stability towards oxidation and with respect to their ability to form a protective film of aluminum fluoride on the aluminum surface. Moreover, the investigation of the electrochemical performance of standard lithium-ion anodes (graphite) and cathodes (Li[Ni1/3 Mn1/3 Co1/3 ]O2 , NMC) in half-cell configuration showed stable cycle life and good rate capability. Finally, an NMC/graphite full-cell confirmed the suitability of such electrolyte compositions for practical lithium-ion cells, thus enabling the complete replacement of LiPF6 and allowing the realization of substantially safer lithium-ion batteries.

  2. Fabrication of ultrathin solid electrolyte membranes of β-Li3PS4 nanoflakes by evaporation-induced self-assembly for all-solid-state batteries

    DOE PAGES

    Wang, Hui; Hood, Zachary D.; Xia, Younan; ...

    2016-04-25

    All-solid-state lithium batteries are attractive candidates for next-generation energy storage devices because of their anticipated high energy density and intrinsic safety. Owing to their excellent ionic conductivity and stability with metallic lithium anodes, nanostructured lithium thiophosphate solid electrolytes such as β-Li3PS4 have found use in the fabrication of all-solid lithium batteries for large-scale energy storage systems. However, current methods for preparing air-sensitive solid electrolyte membranes of lithium thiophosphates can only generate thick membranes that compromise the battery's gravimetric/volumetric energy density and thus its rate performance. To overcome this limitation, the solid electrolyte's thickness needs to be effectively decreased to achievemore » ideal energy density and enhanced rate performance. In this paper, we show that the evaporation-induced self-assembly (EISA) technique produces ultrathin membranes of a lithium thiophosphate solid electrolyte with controllable thicknesses between 8 and 50 μm while maintaining the high ionic conductivity of β-Li3PS4 and stability with metallic lithium anodes up to 5 V. Finally, it is clearly demonstrated that this facile EISA approach allows for the preparation of ultrathin lithium thiophosphate solid electrolyte membranes for all-solid-state batteries.« less

  3. Effects of Nb-doped on the structure and electrochemical performance of LiFePO4/C composites

    NASA Astrophysics Data System (ADS)

    Ma, Zhipeng; Shao, Guangjie; Wang, Guiling; Zhang, Ying; Du, Jianping

    2014-02-01

    The olivine-type niobium doping Li1-xNbxFePO4/C (x=0, 0.005, 0.010, 0.015, 0.025) cathode materials were synthesized via a two-step ball milling solid state reaction. The effects of Nb doping were charactered by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), galvanostatic intermittent titration technique (GITT), cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and galvanostatic charge-discharge. It is found that Nb doping enlarges the interplanar distance of crystal plane parallel to [0 1 0] direction in LiFePO4. In other words, it widens the one dimensional diffusion channels of Li+ along the [0 1 0] direction. Electrochemical test results indicate that the Li0.99Nb0.01FePO4/C composite exhibits the best electrochemical performance with initial special discharge capacity of 139.3 mA h g-1 at 1 C rate. The present synthesis route is promising in making the solid state reaction method more practical for preparation of the LiFePO4 material.

  4. The Effect of Electrolyte Additives upon the Lithium Kinetics of Li-Ion Cells Containing MCMB and LiNi(x)Co(1-x)O2 Electrodes and Exposed to High Temperatures

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Gozdz, A. S.; Mani, S.

    2009-01-01

    With the intent of improving the performance of lithium-ion cells at high temperatures, we have investigated the use of a number of electrolyte additives in experimental MCMB- Li(x)Ni(y)Co(1-y)O2 cells, which were exposed to temperatures as high as 80 C. In the present work, we have evaluated the use of a number of additives, namely vinylene carbonate (VC), dimethyl acetamide (DMAc), and mono-fluoroethylene carbonate (FEC), in an electrolyte solution anticipated to perform well at warm temperature (i.e., 1.0M LiPF6 in EC+EMC (50:50 v/v %). In addition, we have explored the use of novel electrolyte additives, namely lithium oxalate and lithium tetraborate. In addition to determining the capacity and power losses at various temperatures sustained as a result of high temperature cycling (cycling performed at 60 and 80 C), the three-electrode MCMB-Li(x)Ni(y)Co(1-y)O2 cells (lithium reference) enabled us to study the impact of high temperature storage upon the solid electrolyte interphase (SEI) film characteristics on carbon anodes (MCMB-based materials), metal oxide cathodes, and the subsequent impact upon electrode kinetics.

  5. Green synthesis of boron doped graphene and its application as high performance anode material in Li ion battery

    SciTech Connect

    Sahoo, Madhumita; Sreena, K.P.; Vinayan, B.P.; Ramaprabhu, S.

    2015-01-15

    Graphical abstract: Boron doped graphene (B-G), synthesized by simple hydrogen induced reduction technique using boric acid as boron precursor, have more uneven surface as a result of smaller bonding distance of boron compared to carbon, showed high capacity and high rate capability compared to pristine graphene as an anode material for Li ion battery application. - Abstract: The present work demonstrates a facile route for the large-scale, catalyst free, and green synthesis approach of boron doped graphene (B-G) and its use as high performance anode material for Li ion battery (LIB) application. Boron atoms were doped into graphene framework with an atomic percentage of 5.93% via hydrogen induced thermal reduction technique using graphite oxide and boric acid as precursors. Various characterization techniques were used to confirm the boron doping in graphene sheets. B-G as anode material shows a discharge capacity of 548 mAh g{sup −1} at 100 mA g{sup −1} after 30th cycles. At high current density value of 1 A g{sup −1}, B-G as anode material enhances the specific capacity by about 1.7 times compared to pristine graphene. The present study shows a simplistic way of boron doping in graphene leading to an enhanced Li ion adsorption due to the change in electronic states.

  6. Improving rate capability and decelerating voltage decay of Li-rich layered oxide cathodes via selenium doping to stabilize oxygen

    NASA Astrophysics Data System (ADS)

    Ma, Quanxin; Li, Ruhong; Zheng, Rujuan; Liu, Yuanlong; Huo, Hua; Dai, Changsong

    2016-11-01

    To improve the rate performance and decelerate the voltage decay of Li-rich layered oxide cathode materials, a series of cathode materials Li1.2[Mn0.7Ni0.2Co0.1]0.8-xSexO2 (x = 0, 0.07, 0.14 and 0.21) was synthesized via co-precipitation. Based on the characterization results, it can be concluded that uniform Se6+ doping can improve the degree of crystallinity of Li2MnO3, resulting in a better ordering of atoms in the transition metal layer of this type of cathode materials. In the electrochemical experiments, compared to un-doped samples, one of the Se doped samples (LLMO-Se0.14) exhibited a longer sloping region and shorter potential plateau in the initial charge curves, a larger first coulombic efficiency (ca. 77%), better rate capability (178 mAhm g-1 at 10 C) and higher mid-point voltage (MPV) retention (ca. 95%) after 100 cycles. These results prove that Se doping can effectively improve the rate capability and decelerate the voltage decay process of these cathode materials during cycling via suppressing the oxidation process of O2- to O2 and curbing a layered-to-spinel phase transformation. The above-mentioned functions of Se doping are probably due to the higher bonding energy of Sesbnd O than that of Mnsbnd O.

  7. Zr4+ doping in Li4Ti5O12 anode for lithium-ion batteries: open Li+ diffusion paths through structural imperfection.

    PubMed

    Kim, Jae-Geun; Park, Min-Sik; Hwang, Soo Min; Heo, Yoon-Uk; Liao, Ting; Sun, Ziqi; Park, Jong Hwan; Kim, Ki Jae; Jeong, Goojin; Kim, Young-Jun; Kim, Jung Ho; Dou, Shi Xue

    2014-05-01

    One-dimensional nanomaterials have short Li(+) diffusion paths and promising structural stability, which results in a long cycle life during Li(+) insertion and extraction processes in lithium rechargeable batteries. In this study, we fabricated one-dimensional spinel Li4Ti5O12 (LTO) nanofibers using an electrospinning technique and studied the Zr(4+) doping effect on the lattice, electronic structure, and resultant electrochemical properties of Li-ion batteries (LIBs). Accommodating a small fraction of Zr(4+) ions in the Ti(4+) sites of the LTO structure gave rise to enhanced LIB performance, which was due to structural distortion through an increase in the average lattice constant and thereby enlarged Li(+) diffusion paths rather than changes to the electronic structure. Insulating ZrO2 nanoparticles present between the LTO grains due to the low Zr(4+) solubility had a negative effect on the Li(+) extraction capacity, however. These results could provide key design elements for LTO anodes based on atomic level insights that can pave the way to an optimal protocol to achieve particular functionalities.

  8. Atomic disorder of Li0.5Ni0.5O thin films caused by Li doping: estimation from X-ray Debye–Waller factors

    PubMed Central

    Yang, Anli; Sakata, Osami; Yamauchi, Ryosuke; Kumara, L. S. R.; Song, Chulho; Katsuya, Yoshio; Matsuda, Akifumi; Yoshimoto, Mamoru

    2015-01-01

    Cubic type room-temperature (RT) epitaxial Li0.5Ni0.5O and NiO thin films with [111] orientation grown on ultra-smooth sapphire (0001) substrates were examined using synchrotron-based thin-film X-ray diffraction. The 11 and 22 rocking curves including six respective equivalent reflections of the Li0.5Ni0.5O and NiO thin films were recorded. The RT B 1 factor, which appears in the Debye–Waller factor, of a cubic Li0.5Ni0.5O thin film was estimated to be 1.8 (4) Å2 from its 11 and 22 reflections, even though the Debye model was originally derived on the basis of one cubic element. The corresponding Debye temperature is 281 (39) K. Furthermore, the B 2 factor in the pseudo-Debye–Waller factor is proposed. This parameter, which is evaluated using one reflection, was also determined for the Li0.5Ni0.5O thin film by treating Li0.5Ni0.5O and NiO as ideal NaCl crystal structures. A structural parameter for the atomic disorder is introduced and evaluated. This parameter includes the combined effects of thermal vibration, interstitial atoms and defects caused by Li doping using the two Debye–Waller factors. PMID:26664345

  9. Iron-based electrodes meet water-based preparation, fluorine- free electrolyte and binder: a chance for more sustainable Li-ion batteries?

    PubMed

    Valvo, Mario; Liivat, Anti; Eriksson, Henrik; Tai, Cheuk-Wai; Edström, Kristina

    2017-03-10

    Environmentally friendly and cost-effective Li-ion cells are fabricated with abundant, non-toxic LiFePO4 cathodes and Fe oxide anodes. A water-soluble alginate binder is used for coating both electrodes to reduce the environmental footprint. Critical reactivity of LiPF6-based electrolytes toward possible H2O traces in water-processed electrodes is overcome by using a LiBOB salt. The absence of fluorine in both electrolyte and binder is a cornerstone for improved cell chemistry and is demonstrated to result in stable battery operation. A dedicated approach to better exploit conversion-type anodes is also disclosed. The issue of large voltage hysteresis upon conversion/de-conversion is circumvented by operating iron oxide in a deeply lithiated Fe/Li2O form. Li-ion cells with energy efficiencies up to 92% are demonstrated when LiFePO4 is cycled versus such anodes prepared via a pre-lithiation procedure. These cells show an average energy efficiency of ≈90.66% and a mean coulombic efficiency of ≈99.65% over 320 cycles at current densities of 0.1, 0.2 and 0.3 mAcm-2, retaining nearly 100% of their initial discharge capacity and providing an unmatched operation potential of ≈2.85 V for this combination of active materials. No occurrence of Li-plating has been detected in three-electrode cells at charging rates of ≈5C. Excellent rate capabilities up to ≈30C are achieved thanks to the exploitation of size effects due to small Fe nanoparticles and their reactive boundaries.

  10. Performance Testing of Yardney MCMB-LiNiCoAlO2 Lithium-ion Cells Possessing Electrolytes with Improved Safety Characteristics

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Whitcanack, Larry D.; Krause, Frederick C.; Hwang, Constanza; Bugga, Ratnakumar V.; Santee, Stuart; Puglia, Frank J.; Gitzendanner, Rob

    2012-01-01

    Many future NASA missions aimed at exploring the Moon and Mars require high specific energy rechargeable batteries that possess enhanced safety characteristics. There is also a strong desire to develop Li-ion batteries with improved safety characteristics for terrestrial applications, most notably for HEV and PHEV automotive applications. In previous work focused upon evaluating various potential flame retardant additives1, triphenyl phosphate (TPP)2 was observed to have the most desirable attributes, including good life characteristics and resilience to high voltage operation. We have employed a number of approaches in the design of promising TPP-based electrolytes with improved safety, including: (a) varying the flame retardant additive (FRA) content (from 5 to 15%), (b) the use of fluorinated co-solvents, (c) the use of additives to improve compatibility, and (c) the use of ester co-solvents to decrease the viscosity and increase the conductivity. In recent work, we have demonstrated a number of these electrolyte formulations to be compatible with a number of chemistries, including: MCMB carbon-LiNi0.8Co0.2O2, graphite-LiNi0.8Co0.15Al0.05O2, Li-Li(Li0.17Ni 0.25 Mn 0.58 )O2, Li-LiNiCoMnO2 and graphite- LiNiCoMnO2.3,4 In the current study, we have demonstrated the performance of a number of TPP-containing electrolytes in 7 Ah prototype MCMB-LiNiCoO2 cells. We will describe the results of a number of performance tests, including: a) 100% DOD cycle life testing at various temperatures, b) discharge rate characterization as a function of temperature, c) charge rate characterization as a function of temperature, and d) impedance as a function of temperature. In addition to displaying good life characteristics, being comparable to baseline chemistries, a number of cells were observed to provide good performance over a wide temperature range.

  11. Purification of used eutectic (LiCl-KCl) salt electrolyte from pyroprocessing

    NASA Astrophysics Data System (ADS)

    Cho, Yung-Zun; Lee, Tae-Kyo; Eun, Hee-Chul; Choi, Jung-Hoon; Kim, In-Tae; Park, Geun-Il

    2013-06-01

    The separation characteristics of surrogate rare-earth fission products in a eutectic (LiCl-KCl) molten salt were investigated. This system is based on the eutectic salt used for the pyroprocessing treatment of used nuclear fuel (UNF). The investigation was performed using an integrated rare-earth separation apparatus comprising a precipitation reactor, a solid detachment device, and a layer separation device. To separate rare-earth fission products, a phosphate precipitation method using both Li3PO4 and K3PO4 as a precipitant was performed. The use of an equivalent phosphate precipitant composed of 0.408 molar ratio-K3PO4 and 0.592 molar ratio-Li3PO4 can preserve the original eutectic ratio, LiCl-0.592 molar ratio (or 45.2 wt%), as well as provide a high separation efficiency of over 99.5% under conditions of 550 °C and Ar sparging when using La, Nd, Ce, and Pr chlorides. The mixture of La, Nd, Ce, and Pr phosphate had a typical monoclinic (or monazite) structure, which has been proposed as a reliable host matrix for the permanent disposal of a high-level waste form. To maximize the reusability of purified eutectic waste salt after rare-earth separation, the successive rare-earth separation process, which uses both phosphate precipitation and an oxygen sparging method, were introduced and tested with eight rare-earth (Y, La, Ce, Pr, Nd, Sm, Eu and Gd) chlorides. In the successive rare-earth separation process, the phosphate reaction was terminated within 1 h at 550 °C, and a 4-8 h oxygen sparging time were required to obtain over a 99% separation efficiency at 700-750 °C. The mixture of rare-earth precipitates separated by the successive rare-earth separation process was found to be phosphate, oxychloride, and oxide. Through the successive rare-earth separation process, the eutectic ratio of purified salt maintained its original value, and impurity content including the residual precipitant of purified salt can be minimized.

  12. Insights into stability, electronic properties, defect properties and Li ions migration of Na, Mg and Al-doped LiVPO4F for cathode materials of lithium ion batteries: A first-principles investigation

    NASA Astrophysics Data System (ADS)

    Lv, Xiaojun; Xu, Zhenming; Li, Jie; Chen, Jiangan; Liu, Qingsheng

    2016-07-01

    The effects of Na, Mg and Al doping on the structure, electronic property, defect property and Li ions migration of LiVPO4F were investigated by the first-principles method. Calculations show that the processes of forming Li0.875Na0.125VPO4F, α- and β-LiMg0.375V0.75PO4F, α- and β-LiAl0.125V0.875PO4F are all feasible. Na, Mg and Al doping significantly improve the electrical conductivity of LiVPO4F and simultaneously maintain their structural stability attributing to the reduction of band gaps through variations of V-3d spin up orbitals. Li vacancy defects of LiVPO4F are not ignorable, and vacancy defects with a lower activation energy for Li atom are far more likely to occur than Frenkel defects for Li and vacancy defects for other atoms. For pristine LiVPO4F, path D along [0.012 0 . 17 ̅ 0.572] direction is found to have the lowest activation energy of 0.418 eV, suggesting that anisotropic nature of Li ion conduction and LiVPO4F is a one-dimensional (1D)-ion conductor. The corresponding diffusion coefficient was estimated to be 2.82×10-9 cm2/s, which is in good agreement with those experimental values.

  13. Solvent decompositions and physical properties of decomposition compounds in Li-ion battery electrolytes studied by DFT calculations and molecular dynamics simulations.

    PubMed

    Tasaki, Ken

    2005-02-24

    The density functional theory (DFT) calculations have been performed for the reduction decompositions of solvents widely used in Li-ion secondary battery electrolytes, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonates (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), including a typical electrolyte additive, vinylene carbonate (VC), at the level of B3LYP/6-311+G(2d,p), both in the gas phase and solution using the polarizable conductor calculation model. In the gas phase, the first electron reduction for the cyclic carbonates and for the linear carbonates is found to be exothermic and endothermic, respectively, while the second electron reduction is endothermic for all the compounds examined. On the contrary, in solution both first and second electron reductions are exothermic for all the compounds. Among the solvents and the additive examined, the likelihood of undergoing the first electron reduction in solution was found in the order of EC > PC > VC > DMC > EMC > DEC with EC being the most likely reduced. VC, on the other hand, is most likely to undergo the second electron reduction among the compounds, in the order of VC > EC > PC. Based on the results, the experimentally demonstrated effectiveness of VC as an excellent electrolyte additive was discussed. The bulk thermodynamic properties of two dilithium alkylene glycol dicarbonates, dilithium ethylene glycol dicarbonate (Li-EDC) and dilithium 1,2-propylene glycol dicarbonate (Li-PDC), as the major component of solid-electrolyte interface (SEI) films were also examined through molecular dynamics (MD) simulations in order to understand the stability of the SEI film. It was found that film produced from a decomposition of EC, modeled by Li-EDC, has a higher density, more cohesive energy, and less solubility to the solvent than the film produced from decomposition of PC, Li-PDC. Further, MD simulations of the interface between the decomposition compound and graphite suggested

  14. Control of mean ionic radius at Ca site by Sr co-doping for Ce doped LiCaAlF6 single crystals and the effects on optical and scintillation properties

    NASA Astrophysics Data System (ADS)

    Yokota, Yuui; Yamaji, Akihiro; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira

    2014-10-01

    Sr co-doped Ce:LiCaAlF6 [Ce:Li(Ca,Sr)AlF6] crystals with various Ca/Sr ratios were grown by a micro-pulling-down (μ-PD) method and effects of Sr co-doping on crystal structure, chemical composition, optical and scintillation properties for Ce:LiCaAlF6 crystals were investigated as a neutron scintillator. High transparent Ce2%:Li(Ca,Sr)AlF6 crystals with 2% and 5% Sr contents were obtained while Ce2%:Li(Ca,Sr)AlF6 crystals with 10% and 20% Sr contents included milky parts in the crystals. a- and c-axis lengths of Ce:Li(Ca,Sr)AlF6 phase systematically increased with an increase of Sr content. In addition to the emission at 284 and 308 nm from Ce3+ ion, emission peaks at 367 nm appeared by Sr co-doping.

  15. Effect of Mg and Fe Doping on Optical Absorption of LiNbO3 Crystal through First Principles Calculations

    NASA Astrophysics Data System (ADS)

    Huang, Duo-Hui; Yang, Jun-Sheng; Cao, Qi-Long; Wan, Ming-Jie; Li, Qiang; Sun, Liang; Wang, Fan-Hou

    2014-03-01

    Using first principles calculations, we investigate the structural, optical, and electronic properties of LiNbO3 (LN) and M doped LN (M=Mg, Fe). The density of states are calculated to analyze the effect of doping Mg and Fe ions on the absorption spectra and electronic properties of LN. The results show an ultraviolet shift in the optical absorption edge of Mg-doped LN compared with that of intrinsic LN. On the contrary, the absorption edge of Fe-doped LN crystal reveals a red shift. The optical absorption spectra show an improved optical response in the visible range for Mg-doped LN, which significantly differs from that obtained for Fe-doped LN. The electronic excitations from the valence band to the conduction band of LN leads to an improved optical absorption response in the visible region as observed experimentally. The obvious changes of the doped LN crystal are found in some cases, which provide a helpful guide for preparing doped LN crystal.

  16. Ce-doped LiF-SrF2 eutectic scintillators for thermal neutron detection produced at different solidification rates

    NASA Astrophysics Data System (ADS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Fukuda, Kentaro; Kawaguchi, Noriaki; Watanabe, Kenichi; Yamazaki, Atsushi; Uritani, Akira; Chani, Valery

    2013-05-01

    Ce 0.1% doped LiF-SrF2 eutectic scintillators were produced by vertical Bridgman method at various solidification rates of 1, 5, 20, 80, 320, and 1280 mm/hr. The LiF contained 95% of 6Li. The SEM images of the samples solidified at 1-80 mm/hr demonstrated clear lamellar structures. The α-ray induced radioluminescence spectra of the scintillators had intense emission peak at 310 and 330 nm due to the emission from Ce3+ 5d-4f transition of Ce:SrF2 layers. When the samples were irradiated with 252Cf neutrons, they exhibited almost the same light yields of 4500-5500 ph/n and typical decay times of 120-160 ns. The optimal layer thickness of LiF-SrF2 was determined to be 0.9 μm.

  17. Luminescent properties of Tm3+/ Ho3+ co-doped LiYF4 crystals

    NASA Astrophysics Data System (ADS)

    Li, Shan-shan; Xia, Hai-ping; Dong, Yan-ming; Fu, Li; Gu, Xue-mei; Zhang, Jian-li; Wang, Dong-jie; Jiang, Hao-chuan; Chen, Bao-jiu

    2014-11-01

    Ho3+ with various concentrations and Tm3+ with molar concentration of 1.28% are co-doped in LiYF4 (YLF) single crystals. The luminescent properties of the crystals are investigated through emission spectra, emission cross section and decay curves under the excitation of 808 nm. The energy transfer from Tm3+ to Ho3+ and the optimum fluorescence emission of Ho3+ around 2.05 μm are investigated. The emission intensity at 2.05 μm keeps increasing with the molar concentration of Ho3+ improved from 0.50% to 1.51% when the molar concentration of Tm3+ is kept at 1.28%. Moreover, for the co-doped crystals in which the molar concentrations of Tm3+ and Ho3+ are 1.28% and 1.51%, respectively, the maximum emission cross section reaches 0.760×10-20 cm2 and the maximum fluorescence lifetime is 21.98 ms. All the parameters suggest that these materials have more advantages in the future 2.0 μm laser applications.

  18. Dielectric and piezoelectric properties of the KNN ceramic compound doped with Li, La and Ta

    NASA Astrophysics Data System (ADS)

    Fuentes, J.; Portelles, J.; Durruthy-Rodríguez, M. D.; H'Mok, H.; Raymond, O.; Heiras, J.; Cruz, M. P.; Siqueiros, J. M.

    2015-02-01

    With the purpose of improving the dielectric and piezoelectric properties of (K0.5Na0.5)NbO3 (KNN), a multiple doping strategy was tested in this research. Piezoceramics with composition [(K0.5Na0.5)0.94Li0.06]0.97La0.01(Nb0.9Ta0.1)O3 were prepared by the traditional ceramic method. The calcined powders were sintered in their own atmosphere at 1,100 °C for 1.0, 1.5 and 2.5 h. X-ray diffraction analysis showed that the Li+, La3+ and Ta5+ cations diffuse into the KNN structure to form a perovskite-structured solid solution. For 1 h sintering time, a dominant orthorhombic phase is obtained, whereas for the longer times, the dominant phase was tetragonal. The presence of a tetragonal tungsten-bronze minority second phase is confirmed. Scanning electron micrographs show rectangular-shaped grains with a mean size of 1.1 ± 0.2 μm. The existence of pores and traces of a liquid phase favoring grain growth and homogeneity is also observed. Experimental results show an enhancement of the permittivity associated with the enlargement of the c parameter of the cell that increases with sintering time. Li+ incorporation into the structure is made evident by its transition temperature at 400 °C different from those of KNNLaTi (81-110 °C) and KNNLaTa (340 °C). An analysis of the phase transition of the samples indicates a normal rather than a diffuse transition. The electromechanical parameters k p, Q m, σ p, s 11, d 31 and g 31 are determined and compared to those of commercial PZT ceramics.

  19. Dielectric and piezoelectric properties of the KNN ceramic compound doped with Li, La and Ta

    NASA Astrophysics Data System (ADS)

    Fuentes, J.; Portelles, J.; Durruthy-Rodríguez, M. D.; H'Mok, H.; Raymond, O.; Heiras, J.; Cruz, M. P.; Siqueiros, J. M.

    2014-09-01

    With the purpose of improving the dielectric and piezoelectric properties of (K0.5Na0.5)NbO3 (KNN), a multiple doping strategy was tested in this research. Piezoceramics with composition [(K0.5Na0.5)0.94Li0.06]0.97La0.01(Nb0.9Ta0.1)O3 were prepared by the traditional ceramic method. The calcined powders were sintered in their own atmosphere at 1,100 °C for 1.0, 1.5 and 2.5 h. X-ray diffraction analysis showed that the Li+, La3+ and Ta5+ cations diffuse into the KNN structure to form a perovskite-structured solid solution. For 1 h sintering time, a dominant orthorhombic phase is obtained, whereas for the longer times, the dominant phase was tetragonal. The presence of a tetragonal tungsten-bronze minority second phase is confirmed. Scanning electron micrographs show rectangular-shaped grains with a mean size of 1.1 ± 0.2 μm. The existence of pores and traces of a liquid phase favoring grain growth and homogeneity is also observed. Experimental results show an enhancement of the permittivity associated with the enlargement of the c parameter of the cell that increases with sintering time. Li+ incorporation into the structure is made evident by its transition temperature at 400 °C different from those of KNNLaTi (81-110 °C) and KNNLaTa (340 °C). An analysis of the phase transition of the samples indicates a normal rather than a diffuse transition. The electromechanical parameters k p, Q m, σ p, s 11, d 31 and g 31 are determined and compared to those of commercial PZT ceramics.

  20. Resolving the grain boundary and lattice impedance of hot-pressed Li7La3Zr2O12 garnet electrolytes

    DOE PAGES

    Tenhaeff, Wyatt E.; Wang, Yangyang; Sokolov, Alexei P.; ...

    2013-07-24

    Here, the cubic-stabilized garnet solid electrolyte with a nominal composition of Li6.28Al0.24La3Zr2O12 is thoroughly characterized by impedance spectroscopy. By varying the frequency of the applied AC signal over 11 orders of magnitude for characterizations from –100 to +60 °C, the relative contributions of grain and grain boundary conduction are unambiguously resolved.

  1. Lithium ionic mobility study in xLi2CO3-yLiI (x = 95-70, y = 5-30 wt.%) solid electrolyte by impedance spectroscopy technique

    NASA Astrophysics Data System (ADS)

    Omar, Mohd Khari; Ahmad, Azizah Hanom

    2015-08-01

    A detailed systematic study on the effects of different amount (wt.%) of LiI addition on the electrical conductivity and dielectric behavior of the xLi2CO3-xLiI (x = 95-70, y = 5-30 wt.%) electrolyte system was carried out. The samples with different compositions were prepared and ground by mechanical milling method. The electrical and dielectric properties of the samples over a range of frequency (50Hz - 1MHz) were investigated by deploying electrical impedance spectroscopy (EIS) technique in a series of temperature set (298-373K). Normally, Li2CO3 itself shows a very low electrical conductivity (10-5 Scm-1). However, the electrical conductivity of the system was found to be increased (10-3 Scm-1) as the lithium salt (LiI) were introduced to the system. The dielectric analysis displayed that the activation energy was inversely proportional to the increment of LiI (wt.%). As the electrical conductivity reached their maximum value (4.63 × 10-3 Scm-1) at the 20 wt.% of LiI, the activation energy was dropped to the minimum (0.1 eV). The electrical conductivity increases with the temperature (298 - 373K) indicate that the system obeys Arrhenius law.

  2. Lithium ionic mobility study in xLi{sub 2}CO{sub 3}-yLiI (x = 95-70, y = 5-30 wt.%) solid electrolyte by impedance spectroscopy technique

    SciTech Connect

    Omar, Mohd Khari; Ahmad, Azizah Hanom

    2015-08-28

    A detailed systematic study on the effects of different amount (wt.%) of LiI addition on the electrical conductivity and dielectric behavior of the xLi{sub 2}CO{sub 3}-xLiI (x = 95-70, y = 5-30 wt.%) electrolyte system was carried out. The samples with different compositions were prepared and ground by mechanical milling method. The electrical and dielectric properties of the samples over a range of frequency (50Hz – 1MHz) were investigated by deploying electrical impedance spectroscopy (EIS) technique in a series of temperature set (298–373K). Normally, Li{sub 2}CO{sub 3} itself shows a very low electrical conductivity (10{sup −5} Scm{sup −1}). However, the electrical conductivity of the system was found to be increased (10{sup −3} Scm{sup −1}) as the lithium salt (LiI) were introduced to the system. The dielectric analysis displayed that the activation energy was inversely proportional to the increment of LiI (wt.%). As the electrical conductivity reached their maximum value (4.63 × 10{sup −3} Scm{sup −1}) at the 20 wt.% of LiI, the activation energy was dropped to the minimum (0.1 eV). The electrical conductivity increases with the temperature (298 – 373K) indicate that the system obeys Arrhenius law.

  3. Mechanism of charging of Au atoms and nanoclusters on Li doped SiO2/Mo(112) films.

    PubMed

    Martinez, Umberto; Giordano, Livia; Pacchioni, Gianfranco

    2010-02-01

    We present the results of supercell DFT calculations on the adsorption properties of Au atoms and small clusters (Au(n), n < or = 5) on a SiO(2)/Mo(112) thin film and on the same system modified by doping with Li atoms. The adsorbed Li atoms penetrate into the pores of the silica film and become stabilized at the interface where they donate one electron to the Mo metal. As a consequence, the work function of the Li-doped SiO(2)/Mo(112) film is reduced and results in modified adsorption properties. In fact, while on the undoped SiO(2)/Mo(112) film Au interacts only very weakly, on the Li-doped surface Au atoms and clusters bind with significant bond strengths. The calculations show that this is due to the occurrence of an electron transfer from the SiO(2)/Mo(112) interface to the adsorbed gold. The occurrence of the charge transfer is related to the work function of the support but also to the possibility for the silica film to undergo a strong polaronic distortion.

  4. Optimizing Hydrogen Storage by Doping the LiBH4 +MgH2 Reaction with Various Niobium Based Oxides

    NASA Astrophysics Data System (ADS)

    Hornung, Paul; Walko, Robert; Wenzel, Andrew; Wright, Richard; Dobbins, Tabbetha

    In this study, the effects of doping the dehydrogenation reaction of MgH2 + 2LiBH4 was combined with 5 mole% of three different Niobium based oxides (Nb2O5, NbO2, and LiNbO3). The compounds were mixed using high energy ball milling, and then heated using an air tight heating stage. We looked for changes in the Raman spectra as temperature increased (up to 350C) as an indication of hydrogen desorption reaction. We found that milled LiBH4 undergoes significant changes in Raman spectra during heating to 130C. MgH2 undergoes significant changes when comparing before and after milling--but in each case, the spectral peaks remain unchanged during heating to 350C. The sample with LiNbO3 exhibited a concrete change in Raman spectrum at 300 C while the sample doped with Nb2O5 underwent a change in spectra at 170C. The sample doped with NbO2 showed little change in spectra when the samples were heated up to 350C. Further studies are underway to examine the nature of the changes in the Raman spectra using X-ray diffraction and residual gas analysis.

  5. Fano resonance of Li-doped KTa1−xNbxO3 single crystals studied by Raman scattering

    PubMed Central

    Rahaman, M. M.; Imai, T.; Sakamoto, T.; Tsukada, S.; Kojima, S.

    2016-01-01

    The enhancement of functionality of perovskite ferroelectrics by local structure is one of current interests. By the Li-doping to KTa1−xNbxO3 (KTN), the large piezoelectric and electro-optic effects were reported. In order to give new insights into the mechanism of doping, the microscopic origin of the Fano resonance induced by the local structure was investigated in 5%Li-doped KTN single crystals by Raman scattering. The coupling between the continuum states and the transverse optical phonon near 196 cm−1 (Slater mode) caused a Fano resonance. In the vicinity of the cubic-tetragonal phase transition temperature, TC-T = 31 °C, the almost disappearance of the Fano resonance and the remarkable change of the central peak (CP) intensity were observed upon heating. The local symmetry of the polar nanoregions (PNRs), which was responsible for the symmetry breaking in the cubic phase, was determined to E(x, y) symmetry by the angular dependence of Raman scattering. The electric field induced the significant change in the intensity of both CP and Fano resonance. From these experimental results, it is concluded that the origin of the Fano resonance in Li-doped KTN crystals is the coupling between polarization fluctuations of PNRs and the Slater mode, both belong to the E(x, y) symmetry. PMID:27049847

  6. Anisotropy of thermal conductivities in non- and Mg-doped near-stoichiometric LiTaO 3 crystals

    NASA Astrophysics Data System (ADS)

    Nakamura, Masaru; Takekawa, Shunji; Kitamura, Kenji

    2010-09-01

    We investigated the thermal conductivities of non-doped near-stoichiometric LiTaO 3 (SLT) and Mg (1 mol%)-doped near-stoichiometric LiTaO 3 (Mg:SLT) crystals along the X-, Y-, and Z-axes at room temperature. Those of non-doped congruent LiTaO 3 (CLT) crystal along the same axes were also estimated to investigate the effect of non-stoichiometric defects. The thermal conductivities were determined by measuring the thermal diffusivity using a laser-flash method and measuring the specific heat using a differential scanning calorimeter. Anisotropy of the thermal conductivities was found for all three crystals. That is, the thermal conductivities along the X-axis were the same as those along the Y-axis and less than those along the Z-axis. The thermal conductivities of the SLT crystal were the highest and were twice those of the CLT crystal. The thermal conductivities of the Mg:SLT crystal were slightly lower than those of the SLT crystal apparently due to the Mg-doping. We also investigated the effect of the difference in domain structure on thermal conductivity using as-grown Mg:SLT crystal with randomly distributed multi-domains and found that it did not affect the thermal conductivity along any axis. These findings regarding thermal conductivity should be useful for designing high-power laser applications using SLT and Mg:SLT crystals.

  7. Doping Li and K into Na2ZrO3 Sorbent to Improve Its CO2 Capture Capability

    NASA Astrophysics Data System (ADS)

    Duan, Yuhua

    Carbon dioxide is one of the major combustion products which once released into the air can contribute to global climate change. Solid sorbents have been reported in several previous studies to be promising candidates for CO2 sorbent applications due to their high CO2 absorption capacities at moderate working temperatures. However, at a given CO2 pressure, the turnover temperature (Tt) of an individual solid capture CO2 reaction is fixed and may be outside the operating temperature range (ΔTo) for a particularly capture technology. In order to shift such Tt for a solid into the range of ΔTo, its corresponding thermodynamic property must be changed by changing its structure by reacting (mixing) with other materials or doping with other elements. As an example, by combining thermodynamic database searching with ab initio thermodynamics calculations, in this work, we explored the Li- and K-doping effects on the Tt shifts of Na2ZrO3 at different doping levels. The obtained results showed that compared to pure Na2ZrO3, the Li- and K-doped mixtures Na2-αMαZrO3 (M =Li, K) have lower Tt and higher CO2 capture capacities.

  8. Shuttle inhibition by chemical adsorption of lithium polysulfides in B and N co-doped graphene for Li-S batteries.

    PubMed

    Li, Fen; Su, Yan; Zhao, Jijun

    2016-09-14

    The advance of lithium sulfur batteries is now greatly restricted by the fast capacity fading induced by shuttle effect. Using first-principles calculations, various vacancies, N doping, and B,N co-doping in graphene sheets have been systematically explored for lithium polysufides entrapped in Li-S batteries. The LiS, LiC, LiN and SB bonds and Hirshfeld charges in the Li2S6 adsorbed defective graphene systems have been analyzed to understand the intrinsic mechanism of retaining lithium polysulfides in these systems. Total and local densities of states analyses elucidate the strongest adsorption sites among the N and B-N co-doped graphene systems. The overall electrochemical performance of Li-S batteries varies with the types of defects in graphene. Among the defective graphene systems, only the reconstructed pyrrole-like vacancy is effective for retaining lithium polysulfides. N doping induces a strong LiN interaction in the defective graphene systems, in which the pyrrolic N rather than the pyridinic N plays a dominant role in trapping of lithium polysulfides. The shuttle effect can be further depressed via pyrrolic B,N co-doped defective graphene materials, especially the G-B-N-hex system with extremely strong adsorption of lithium polysulfides (4-5 eV), and simultaneous contribution from the strong LiN and SB interactions.

  9. Boron-doped diamond electrooxidation of ethyl paraben: The effect of electrolyte on by-products distribution and mechanisms.

    PubMed

    Frontistis, Zacharias; Antonopoulou, Maria; Yazirdagi, Melis; Kilinc, Zeynep; Konstantinou, Ioannis; Katsaounis, Alexandros; Mantzavinos, Dionissios

    2016-07-01

    Ethyl paraben (EP), a representative emerging pollutant of the parabens family, was subject to electrochemical oxidation over a boron-doped diamond (BDD) anode. Experiments were carried out in a single-compartment cell at 10-70 mA cm(-2) current density, 200-600 μg L(-1) EP concentration, initial solution pH 3-9 and 0.1 M electrolyte concentration. The degradation rate is favored at increased current densities and in the presence of NaCl as the supporting electrolyte, while the pH effect is inconsiderable. For instance, the first order rate constant for the degradation of 200 μg L(-1) EP at 30 mA cm(-2) was 0.25, 0.1 and 0.07 min(-1) with NaCl, Na2SO4 and HClO4, respectively. Degradation in secondary treated wastewater was faster than in pure water presumably due to the action of chloride ions present in the effluent. Liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) was employed to determine major transformation by-products (TBPs). The route of EP degradation with Na2SO4 involves hydroxylation and demethylation reactions, signifying the role of electrogenerated hydroxyl radicals in the process. Twenty one TBPs were identified with NaCl as the electrolyte, including several chlorinated and non-chlorinated dimers and trimers; these findings suggest that indirect oxidation mediated by chlorine radicals and other chlorine active species also takes place. In this view, the role of the supporting electrolyte is crucial since it can influence both reaction kinetics and pathways.

  10. Structural, Vibrational, Thermal And Electrical Characterization Of Gamma Radiation-Crosslinked Poly (Vinyl Alcohol)-Based Solid Polymer Electrolytes Blended With LiOHṡH2O Salt

    NASA Astrophysics Data System (ADS)

    Khafagy, Rasha M.; Madani, M.; Badr, Y. A.

    2008-09-01

    Solid polymer electrolytes based on poly(vinyl alcohol) (PVA) blended with different concentrations of LiOHṡH2O salt were prepared using casting and γ-irradiation techniques. The structure and blending of the poly-electrolytes were studied by X-ray diffraction (XRD) and Fourier transform Raman spectroscopy. The thermal properties of these solid polymer electrolytes were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD spectra for the electrolytes indicated that the crystalline ratio of PVA decreases with the concentration of Lithium salt. Crystallinity, isotacticity and syndiotacticity percentages were also determined from Raman spectra at different salt concentrations revealing that the crystallinity and the Isotactic regularity of PVA molecule is reduced with salt addition, while the syndiotacticity increases linearly. DSC thermograms showed good accordance with these facts by detecting two melting temperatures corresponding to the two regularities, and these melting points change with the salt content. All characterizing techniques revealed the blend formation between LiOHṡH2O salt and the polymer matrix. To account for the performance of the prepared solid polymer electrolytes, thermally stimulated depolarization current (TSDC) studies of the prepared blends were done. Short circuit TSDC at a polarizing temperature 353 K with a polarizing field of 3 kV cm-1 have been analyzed in the temperature range 300-410 K. Two peaks are evident from the global TSDC measurements on the pure PVA homopolymer. Meanwhile, in all blended samples; there is only one broad peak with a shoulder on the high temperature side due to the relaxation of the poly-blend system. The prepared solid polymer electrolytes showed good charge storage capacity, and moderate current density values near the ambient.

  11. Synthesis, characterization and modification of LiFePO4 by doping with platinum and palladium for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Talebi-Esfandarani, Majid

    Lithium iron phosphate (LiFePO4) with features of excellent thermal stability, non-toxicity, low cost and abundance in nature is one of the most promising cathode materials to be used in lithium ion batteries. However, as it suffers from the low electrical conductivity and poor ionic diffusion, it operates only at low charge/discharge current rates. In this thesis, a dual approach of metal doping and carbon coating was employed to solve the aforementioned problem. This work is mainly on the study, for the first time, of the effect of platinum and palladium doping of LiFePO 4 on its physical-chemical properties. The effect of Pt and Pd doping on the LiFePO4 performance as Li-ion cathode will be also shown. Sol-gel and hydrothermal methods were used to synthesize the LiFePO4 and doped-LiFePO4 cathode materials. The prepared materials were characterized using different methods such as XRD (X-ray Diffraction), XPS (X-ray Photoelectron Spectroscopy), SEM (Scanning Electron Microscopy) and BET (Brunauer Emmett Teller). The electrochemical characterization techniques including charge/discharge test, CV (Cyclic Voltammetry), EIS (Electrochemical Impedance Spectroscopy) and cycling were also used. The effects of metals doping on chemical-physical properties, particles sizes, morphology, structure and purity of the electrodes were investigated and their correlation to the electrochemical properties of materials were studied. In the first section, we determine the optimized amount of carbon support and morphology of the particles using SEM which help to obtain LiFePO 4/C cathode material with an excellent electrochemical performance. It was found that when the amount of coated carbon exceeds the optimized value, the discharge capacity of the LiFePO4/C material decreased. This might indicate a low diffusion of the Li+ ions through the carbon layers during the charge/discharge process. On the other hand, for LiFePO4 coated with carbon quantity lower than the optimum value, Li

  12. Self-discharge suppression of 4.9 V LiNi0.5Mn1.5O4 cathode by using tris(trimethylsilyl)borate as an electrolyte additive

    NASA Astrophysics Data System (ADS)

    Liao, Xiaolin; Huang, Qiming; Mai, Shaowei; Wang, Xianshu; Xu, Mengqing; Xing, Lidan; Liao, Youhao; Li, Weishan

    2014-12-01

    In this paper, tris(trimethylsilyl)borate (TMSB) is evaluated as an electrolyte additive for the self-discharge suppression of 4.9 V LiNi0.5Mn1.5O4 cathode for lithium ion battery. The effect of TMSB on the surface properties of LiNi0.5Mn1.5O4 is investigated via linear sweep voltammetry (LSV), cyclic voltammetry (CV), chronoamperometry (CA), charge-discharge test, electrochemical impedance spectra (EIS), scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometer (ICP-AES) and Fourier transform infrared spectroscopy (FTIR). It is found that the LiNi0.5Mn1.5O4 cathode charged to 4.9 V (vs. Li/Li+) suffers a serious self-discharge in 1 mol L-1 LiPF6-EC/DMC (1:2, in weight), which can be suppressed effectively by adding 1 wt.% TMSB into the electrolyte. After storage for 20 days, the voltage of the charged cathode decreases from 4.7 to 0.5 V (vs. Li/Li+) in the additive-free electrolyte, while that remains almost unchanged in the TMSB-containing electrolyte. The self-discharge suppression of the charged LiNi0.5Mn1.5O4 cathode results from the preferential oxidation of TMSB and the subsequent formation of a protective solid electrolyte interphase film, which prevents electrolyte decomposition and protects LiNi0.5Mn1.5O4 from destruction.

  13. Enhanced nonvolatile holographic properties in Zn, Ru and Fe co-doped LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Xu, Chao; Leng, Xuesong; Xu, Lei; Wen, Aihua; Xu, Yuheng

    2012-08-01

    A series of LiNbO3 crystals doped with various concentrations of ZnO and fixed concentrations of RuO2 and Fe2O3 have been grown by the Czochralski method from the congruent melts. The type of charge carriers was determined by Kr+ laser (476 nm) and He-Ne laser (633 nm). The results revealed that the holes were the dominant charge carriers at blue light irradiation. Dual-wavelength and two-color techniques were employed to investigate the nonvolatile holographic storage properties of Ru:Fe:LiNbO3 and Zn doped Ru:Fe:LiNbO3 crystals. The essential parameters of blue nonvolatile holographic storage in Zn:Ru:Fe:LiNbO3 crystals were enhanced greatly with the increase of Zn concentration. This indicates that the damage resistant dopants Zn2+ ions enhance the photorefractive properties at 476 nm wavelength instead of suppressing the photorefraction. The different mechanisms of blue photorefractive and nonvolatile holographic storage properties by dual wavelength recording in Zn:Ru:Fe:LiNbO3 crystals were discussed.

  14. Li doping effect on the photoluminescence behaviors of KSrPO{sub 4}:Dy{sup 3+} phosphors for WLED light

    SciTech Connect

    Gou, Jing; Wang, Jing; Yu, Binxun; Duan, Dongyu; Ye, Shufen; Liu, Shengzhong

    2015-04-15

    Highlights: • The luminescence intensity of KSrPO{sub 4}:Dy{sup 3+} can be increased with Li{sup +} ions co-doping. • The mechanisms for the emitting enhancement with Li{sup +} ions co-doping were investigated. • The thermal stability demonstrated that KSrPO{sub 4}:0.01Dy{sup 3+}, 0.06Li{sup +} is suitable for WLEDs. • The chromaticity coordinates of KSrPO{sub 4}:Dy{sup 3+}, Li{sup +} can be tuned with Li{sup +} ions increasing. - Abstract: A novel warm-white phosphor KSrPO{sub 4} co-doped with Dy{sup 3+} and Li{sup +} ions was prepared by solid state reaction. A strategy of Li{sup +} doping was used with the aim of enhancing the luminescence of 475 nm and 570 nm emission bands under NUV excitation. Compared to lithium-free KSrPO{sub 4}:Dy{sup 3+}, the intensities of the 570 nm emission peaks were increased by 4.32 times and 2.84 times excited by 351 nm and 388 nm with 6 mol% Li{sup +} ions co-doping, respectively. The mechanism of the enhancement was discussed, that is due to the improvement of the phosphors’ crystallinity and charge compensation when the Li{sup +} ions were introduced. Furthermore, the thermal stability of KSrPO{sub 4}:0.01Dy{sup 3+}, 0.06Li{sup +} was measured and discussed, demonstrating it can be applied for high-powered LED. And the chromaticity coordinates of KSrPO{sub 4}:0.01Dy{sup 3+}, xLi{sup +} can be tuned efficiently from the cold-white region to warm-white region with Li{sup +} ions increasing, presenting its potential applied value as a new warm-white LED phosphor.

  15. Thermal neutron imaging with rare-earth-ion-doped LiCaAlF 6 scintillators and a sealed 252Cf source

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Noriaki; Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui; Kamada, Kei; Fukuda, Kentaro; Suyama, Toshihisa; Watanabe, Kenichi; Yamazaki, Atsushi; Chani, Valery; Yoshikawa, Akira

    2011-10-01

    Thermal neutron imaging with Ce-doped LiCaAlF 6 crystals has been performed. The prototype of the neutron imager using a Ce-doped LiCaAlF 6 scintillating crystal and a position sensitive photomultiplier tube (PSPMT) which had 64 multi-channel anode was developed. The Ce-doped LiCaAlF 6 single crystal was grown by the Czochralski method. A plate with dimensions of a diameter of 50×2 mm 2 was cut from the grown crystal, polished, and optically coupled to PSPMT by silicone grease. The 252Cf source (<1 MBq) was sealed with 43 mm of polyethylene for neutron thermalization. Alphabet-shaped Cd pieces with a thickness of 2 mm were used as a mask for the thermal neutrons. After corrections for the pedestals and gain of each pixel, we successfully obtained two-dimensional neutron images using Ce-doped LiCaAlF 6.

  16. Electrochemical and interfacial properties of (PEO)10LiCF3SO3-Al2O3 nanocomposite polymer electrolytes using ball milling

    NASA Astrophysics Data System (ADS)

    Shin, J. H.; Jung, B. S.; Jeong, S. S.; Kim, K. W.; Ahn, H. J.; Cho, K. K.; Ahn, J. H.