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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. 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).

  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 Bradley; Bennett, William Raymond; Wu, James J.; Hernandez, Dionne M.; Borodin, Oleg; Monk, Joshua D.; Bauschlicher, Charles W., Jr.; Watson, 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. 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.

  6. Li3PO4-doped Li7P3S11 glass-ceramic electrolytes with enhanced lithium ion conductivities and application in all-solid-state batteries

    NASA Astrophysics Data System (ADS)

    Huang, Bingxin; Yao, Xiayin; Huang, Zhen; Guan, Yibiao; Jin, Yi; Xu, Xiaoxiong

    2015-06-01

    70Li2S·(30-x)P2S5·xLi3PO4 (mol%) amorphous powders are prepared by a high-energy ball milling technique, and the glass-ceramics are obtained by the crystallization of as-prepared amorphous samples. The XRD patterns show that a crystalline phase with a Li7P3S11 structure is obtained for x ≤ 3, while a structure change is observed for x = 5. The Li+-ion conductivity is enhanced by the substitution of Li3PO4 for P2S5, and the 70Li2S·29P2S5·1Li3PO4 glass-ceramics exhibit the highest total conductivity of 1.87 × 10-3 S cm-1 at 25 °C and the lowest activation energy of 18 kJ mol-1. The LiCoO2 in the all-solid-state cell of In-Li/70Li2S·29P2S5·1Li3PO4/LiCoO2 exhibits a discharge capacity of 108 mAh g-1, which is 20% higher than that in the In-Li/70Li2S·30P2S5/LiCoO2 cell. The higher discharge capacity of the LiCoO2 electrode is attributed to the higher Li+-ion conductivity of the solid electrolyte and lower interface resistance of electrode-electrolyte.

  7. 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.

  8. 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

    2014-01-01

    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. PMID:25023009

  9. 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

  10. Synergistic multi-doping effects on the Li7La3Zr2O12 solid electrolyte for fast lithium ion conduction.

    PubMed

    Shin, Dong Ok; Oh, Kyungbae; Kim, Kwang Man; Park, Kyu-Young; Lee, Byungju; Lee, Young-Gi; Kang, Kisuk

    2015-01-01

    Here, we investigate the doping effects on the lithium ion transport behavior in garnet Li7La3Zr2O12 (LLZO) from the combined experimental and theoretical approach. The concentration of Li ion vacancy generated by the inclusion of aliovalent dopants such as Al(3+) plays a key role in stabilizing the cubic LLZO. However, it is found that the site preference of Al in 24d position hinders the three dimensionally connected Li ion movement when heavily doped according to the structural refinement and the DFT calculations. In this report, we demonstrate that the multi-doping using additional Ta dopants into the Al-doped LLZO shifts the most energetically favorable sites of Al in the crystal structure from 24d to 96 h Li site, thereby providing more open space for Li ion transport. As a result of these synergistic effects, the multi-doped LLZO shows about three times higher ionic conductivity of 6.14 × 10(-4) S cm(-1) than that of the singly-doped LLZO with a much less efforts in stabilizing cubic phases in the synthetic condition. PMID:26666197

  11. Synergistic multi-doping effects on the Li7La3Zr2O12 solid electrolyte for fast lithium ion conduction

    NASA Astrophysics Data System (ADS)

    Shin, Dong Ok; Oh, Kyungbae; Kim, Kwang Man; Park, Kyu-Young; Lee, Byungju; Lee, Young-Gi; Kang, Kisuk

    2015-12-01

    Here, we investigate the doping effects on the lithium ion transport behavior in garnet Li7La3Zr2O12 (LLZO) from the combined experimental and theoretical approach. The concentration of Li ion vacancy generated by the inclusion of aliovalent dopants such as Al3+ plays a key role in stabilizing the cubic LLZO. However, it is found that the site preference of Al in 24d position hinders the three dimensionally connected Li ion movement when heavily doped according to the structural refinement and the DFT calculations. In this report, we demonstrate that the multi-doping using additional Ta dopants into the Al-doped LLZO shifts the most energetically favorable sites of Al in the crystal structure from 24d to 96 h Li site, thereby providing more open space for Li ion transport. As a result of these synergistic effects, the multi-doped LLZO shows about three times higher ionic conductivity of 6.14 × 10-4 S cm-1 than that of the singly-doped LLZO with a much less efforts in stabilizing cubic phases in the synthetic condition.

  12. Synergistic multi-doping effects on the Li7La3Zr2O12 solid electrolyte for fast lithium ion conduction

    PubMed Central

    Shin, Dong Ok; Oh, Kyungbae; Kim, Kwang Man; Park, Kyu-Young; Lee, Byungju; Lee, Young-Gi; Kang, Kisuk

    2015-01-01

    Here, we investigate the doping effects on the lithium ion transport behavior in garnet Li7La3Zr2O12 (LLZO) from the combined experimental and theoretical approach. The concentration of Li ion vacancy generated by the inclusion of aliovalent dopants such as Al3+ plays a key role in stabilizing the cubic LLZO. However, it is found that the site preference of Al in 24d position hinders the three dimensionally connected Li ion movement when heavily doped according to the structural refinement and the DFT calculations. In this report, we demonstrate that the multi-doping using additional Ta dopants into the Al-doped LLZO shifts the most energetically favorable sites of Al in the crystal structure from 24d to 96 h Li site, thereby providing more open space for Li ion transport. As a result of these synergistic effects, the multi-doped LLZO shows about three times higher ionic conductivity of 6.14 × 10−4 S cm−1 than that of the singly-doped LLZO with a much less efforts in stabilizing cubic phases in the synthetic condition. PMID:26666197

  13. Lithium dope and undope reactions for tin in an ionic liquid electrolyte with some glymes

    NASA Astrophysics Data System (ADS)

    Katayama, Yasushi; Miyashita, Sodai; Miura, Takashi

    Lithium doped and undoped reactions for tin have been investigated in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing 0.1 M LiTFSA with some glymes. Lithium doped and undoped for tin were found to be possible in the ionic liquid electrolyte in both absence and presence of glymes. The interfacial resistance for lithium doped and undoped reactions in the ionic liquid electrolyte was decreased by addition of 0.2 M glymes probably due to the coordination of the glymes to Li +. It was suggested that the interfacial resistance is strongly affected by the coordination environment of Li + in the ionic liquid electrolyte.

  14. 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. PMID:27356953

  15. 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

  16. Raising the conductivity of crystalline polymer electrolytes by aliovalent doping.

    PubMed

    Zhang, Chuhong; Staunton, Edward; Andreev, Yuri G; Bruce, Peter G

    2005-12-28

    Polymer electrolytes, salts dissolved in solid polymers, hold the key to realizing all solid-state devices such as rechargeable lithium batteries, electrochromic displays, or SMART windows. For 25 years conductivity was believed to be confined to amorphous polymer electrolytes, all crystalline polymer electrolytes were thought to be insulators. However, recent results have demonstrated conductivity in crystalline polymer electrolytes, although the levels at room temperature are too low for application. Here we show, for the first time, that it is possible to raise significantly the level of ionic conductivity by aliovalent doping. The conductivity may be raised by 1.5 orders of magnitude if the SbF6- ion in the crystalline conductor poly(ethylene oxide)6:LiSbF6 is replaced by less than 5 mol % SiF6(2-), thus introducing additional, mobile, Li+ ions into the structure to maintain electroneutrality. PMID:16366585

  17. 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.

  18. 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.

  19. Stability of the Solid Electrolyte Interface on the Li Electrode in Li-S Batteries.

    PubMed

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

    2016-04-27

    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. PMID:27045986

  20. Li2OHCl Crystalline Electrolyte for Stable Metallic Lithium Anodes

    SciTech Connect

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

    2016-01-01

    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. To understand this excellent stability, we show that SEI formation is critical in stabilizing the interface between metallic lithium and the Li2OHCl solid electrolyte.

  1. 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.

  2. Li2OHCl crystalline electrolyte for stable metallic lithium anodes

    DOE PAGESBeta

    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 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

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

    DOE PAGESBeta

    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. 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

  4. 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.

  5. 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.

  6. First-Principles Study of LiPON Solid Electrolyte

    NASA Astrophysics Data System (ADS)

    Santosh, K. C.; Xiong, Ka; Cho, Kyeongjae

    2011-03-01

    There has been much interest in the thin-film solid electrolyte for solid state battery and ionics applications. LiPON is a representative material developed by Oak Ridge National Laboratory. In this work, we use first principles calculations based on the density functional theory to investigate the Li- ion migration mechanisms of LiPON family materials. We investigate atomic structures, electronic structures and defect formation energies of these materials. To determine the migration path of Li diffusion, the activation energies are calculated. This study helps us to understand fundamental mechanisms of Li-ion migration and to improve Li ion conductivity in the solid electrolytes.

  7. 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.

  8. Li diffusion through doped and defected graphene.

    PubMed

    Das, Deya; Kim, Seungchul; Lee, Kwang-Ryeol; Singh, Abhishek K

    2013-09-28

    We investigate the effect of nitrogen and boron doping on Li diffusion through defected graphene using first principles based density functional theory. While a high energy barrier rules out the possibility of Li- diffusion through the pristine graphene, the barrier reduces with the incorporation of defects. Among the most common defects in pristine graphene, Li diffusion through the divacancy encounters the lowest energy barrier of 1.34 eV. The effect of nitrogen and boron doping on the Li diffusion through doped defected-graphene sheets has been studied. N-doping in graphene with a monovacancy reduces the energy barrier significantly. The barrier reduces with the increasing number of N atoms. On the other hand, for N doped graphene with a divacancy, Li binds in the plane of the sheet, with an enhanced binding energy. The B doping in graphene with a monovacancy leads to the enhancement of the barrier. However, in the case of B-doped graphene with a divacancy, the barrier reduces to 1.54 eV, which could lead to good kinetics. The barriers do not change significantly with B concentration. Therefore, divacancy, B and N doped defected graphene has emerged as a better alternative to pristine graphene as an anode material for Li ion battery. PMID:23925460

  9. Effect of ion structure on conductivity in lithium-doped ionic liquid electrolytes: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Liu, Hongjun; Maginn, Edward

    2013-09-01

    Molecular dynamics simulations were performed to examine the role cation and anion structure have on the performance of ionic liquid (IL) electrolytes for lithium conduction over the temperature range of 320-450 K. Two model ionic liquids were studied: 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([bmim][Tf2N]) and 1-butyl-4-methylpyridinium pyrrolide ([bmpyr][pyl]) doped with Li[Tf2N] and Li[pyl], respectively. The results have demonstrated that the Li+ doped IL containing the planar [bmpyr] cation paired with the planar [pyl] anion significantly outperformed the [bmim][Tf2N] IL. The different coordination of Li+ with the [Tf2N]- or [pyl]- anions produces a remarkable change in IL structure with a concomitant effect on the transport of all ions. For the doped [bmim][Tf2N], each Li+ is coordinated by four oxygen atoms from [Tf2N]- anions. Formation of a rigid structure between Li+ and [Tf2N]- induces a decrease in the mobility of all ions. In contrast, for the doped [bmpyr][pyl], each Li+ is coordinated by two nitrogen atoms from [pyl]- anions. The original alternating structure cation|anion|cation in the neat [bmpyr][pyl] is replaced by another alternating structure cation|anion|Li+|anion|cation in the doped [bmpyr][pyl]. Increases of Li+ mole fraction in doped [bmpyr][pyl] affects the dynamics to a much lesser extent compared with [bmim][Tf2N] and leads to reduced diffusivities of cations and anions, but little change in the dynamics of Li+. More importantly, the calculations predict that the Li+ ion conductivity of doped [bmpyr][pyl] is comparable to that observed in organic liquid electrolytes and is about an order of magnitude higher than that of doped [bmim][Tf2N]. Such Li+ conductivity improvement suggests that this and related ILs may be promising candidates for use as electrolytes in lithium ion batteries and capacitors.

  10. 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.

  11. Self-doped microphase separated block copolymer electrolyte

    DOEpatents

    Mayes, Anne M.; Sadoway, Donald R.; Banerjee, Pallab; Soo, Philip; Huang, Biying

    2002-01-01

    A polymer electrolyte includes a self-doped microphase separated block copolymer including at least one ionically conductive block and at least one second block that is immiscible in the ionically conductive block, an anion immobilized on the polymer electrolyte and a cationic species. The ionically conductive block provides a continuous ionically conductive pathway through the electrolyte. The electrolyte may be used as an electrolyte in an electrochemical cell.

  12. 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

  13. Improving sulfolane-based electrolyte for high voltage Li-ion cells with electrolyte additives

    NASA Astrophysics Data System (ADS)

    Xia, Jian; Dahn, J. R.

    2016-08-01

    An electrolyte mixture containing 1 M LiPF6 in sulfolane:ethylmethyl carbonate 3:7 with vinylene carbonate and other electrolyte additives exhibited promising cycling and storage performance in high voltage Li(Ni0·4Mn0·4Co0.2)O2/graphite pouch type Li-ion cells tested to 4.5 V. Voltage drop during storage, coulombic efficiency, charge endpoint capacity slippage during ultra high precision cycling, charge-transfer resistance after storage or cycling, gas evolution during storage and cycling as well as capacity retention during long-term cycling were examined. The results for cells with sulfolane-based electrolytes were compared with those for cells with ethylene carbonate-based electrolytes containing state-of-the-art electrolyte additives. This survey showed that the combination of vinylene carbonate and triallyl phosphate as electrolyte additives in sulfolane:ethylmethyl carbonate electrolyte yielded cells capable of better performance during tests to 4.5 V than cells with ethylene carbonate-based electrolytes. These results suggest that sulfolane-based electrolytes may be promising for high voltage Li-ion cells.

  14. 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.

  15. 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

  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 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.

  18. Power capability improvement of LiBOB/PC electrolyte for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Kaneko, Hiroaki; Sekine, Kyoichi; Takamura, Tsutomu

    Lithium bis(oxalto)borate (LiBOB) is quite effective to prevent vigorous decomposition of propylene carbonate (PC) at the graphite anode of a Li-ion battery during Li insertion. PC is a very good solvent that is inexpensive, has high conductivity and a low melting point; however, the power capability of PC electrolyte containing LiBOB is unsatisfactory. In an attempt to improve the power capability of the LiBOB/PC electrolyte, mixed electrolytes containing both LiBOB and LiClO 4 were examined. An integrated fiber felt of highly graphitized carbon was used as the working electrode and the performance was evaluated by cyclic voltammetry (CV), constant current followed by constant voltage charge (CCCV) and constant current discharge. The CV produced a stable peak for Li extraction, but the peak height was as low as half that obtained in a conventional electrolyte such as a 1:1 mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) containing 1 M LiClO 4. However, the peak height in PC, containing 1/49 M LiBOB and 1 M LiClO 4, became 1.5 times higher than that in PC containing 1 M LiBOB. The peak height was increased further using a 1:1 mixture of PC and acetonitrile (AN) containing 1/49 M LiBOB and 1 M LiClO 4, although the cycleability was poor. A similar tendency was observed with the CCCV test. The CV peak height was plotted against the ionic conductivity of several solvents and showed no linear relationship, implying that the reaction activity was influenced by the solid electrolyte interphase (SEI) formed. The charge transfer resistance was evaluated by impedance spectroscopy. The results revealed that not only the surface film resistance but also the charge transfer resistance was markedly increased in the electrolyte containing LiBOB; however, they were reduced by the addition of LiClO 4.

  19. 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.

  20. Chemical stability enhancement of lithium conducting solid electrolyte plates using sputtered LiPON thin film

    NASA Technical Reports Server (NTRS)

    West, W. C.; Whitacre, J. F.; Lim, J. R.

    2004-01-01

    Sputter deposition of LiPON films directly onto high Li+ conductivity solid electrolyte plates has been investigated as a means to minimize the reactivity of the plates to metallic Li. The LiPON films were shown to effectively passivate the plates in contact with metallic Li, in contrast to unpassivated plates that reacted immediately in contact with Li metal.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Anand, P. B.; Jayalekshmi, S.

    2014-01-01

    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.

  3. Electronic Properties of LiFePO4 and Li doped LiFePO4

    SciTech Connect

    Allen, J.L.; Zhuang, G.V.; Ross, P.N.; Guo, J.-H.; Jow, T.R.

    2006-05-31

    LiFePO{sub 4} has several potential advantages in comparison to the transition metal oxide cathode materials used in commercial lithium-ion batteries. However, its low intrinsic electronic conductivity ({approx} 10{sup -9} S/cm) is problematic. We report here a study by soft x-ray absorption/emission spectroscopy of the electronic properties of undoped LiFePO{sub 4} and Li-doped LiFePO{sub 4} in which Li{sup +} ions are substituted for Fe{sup 2+} ions in an attempt to increase the intrinsic electronic conductivity. The conductivities of the Li{sub 1+x}Fe{sub 1-x}PO{sub 4} samples were, however, essentially unchanged from that of the undoped LiFePO{sub 4}. Nonetheless, evidence for changing the electronic properties of LiFePO{sub 4} by doping with excess Li+ was observed by the XAS/XES spectroscopy. New pre-edge features the O-1s XAS spectrum of Li{sub 1.05}Fe{sub 0.95}PO4 is a direct indication that the charge compensation for substitution of Fe{sup 2+} by Li{sup +} resides in the unoccupied O-2p orbitals. A charge transfer (CT) excitation was also observed in the doped material implying that the unoccupied O-2p orbitals created by doping are strongly hybridized with unoccupied Fe-3d orbitals of neighboring sites. However, the strong covalent bonding within the (PO{sub 4}){sup 3-} anions and the large separation of the Fe cations means that the charge created by doping is not delocalized in the manner of electrons or holes in a semiconductor.

  4. Chemical stability enhancement of lithium conducting solid electrolyte plates using sputtered LiPON thin films

    NASA Astrophysics Data System (ADS)

    West, W. C.; Whitacre, J. F.; Lim, J. R.

    Sputter deposition of LiPON films directly onto high Li + conductivity solid electrolyte plates has been investigated as a means to minimize the reactivity of the plates to metallic Li. The LiPON films were shown to effectively passivate the plates in contact with metallic Li, in contrast to unpassivated plates that reacted immediately in contact with Li metal. The conductivity of the passivated solid electrolyte plates was measured to be 1.0×10 -4 S cm -1, with Arrhenius activation energy of 0.36 eV and an electrochemical stability window of at least 0-5.0 V versus Li/Li +. The passivated solid electrolyte was capable of supporting electrochemical plating and stripping of Li metal, as demonstrated by EIS and CV measurements. These high chemical stability, high Li + conductivity solid electrolyte plates will be useful for solid-state batteries employing Li anodes.

  5. Electrolyte effects in Li(Si)/FeS{sub 2} thermal batteries

    SciTech Connect

    Guidotti, R.A.; Reinhardt, F.W.

    1994-10-01

    The most common electrochemical couple for thermally activated (``thermal``) batteries is the Li-alloy/FeS{sub 2} system. The most common Li-alloys used for anodes are 20% Li-80% Al and 44% Li-56% Si (by weight); liquid Li immobilized with iron powder has also been used. The standard electrolyte that has been used in thermal batteries over the years is the LiCl-KCl eutectic that melts at 352{degrees}C. The LiCl-LiBr-LiF eutectic had the best rate and power characteristics. This electrolyte melts at 436{degrees}C and shows very low polarization because of the absence of Li+ gradients common with the LiCl-KCl eutectic. The low-melting electrolytes examined included a KBr-LiBr-LiCl eutectic (melting at 321{degrees}C), a LiBr-KBr-LiF eutectic (melting at 313{degrees}C), and a CsBr-LiBr-KBr eutectic (melting at 238{degrees}C). The CsBr-based salt had poor conductivity and was not studied further. The LiBr-KBr-LiF eutectic outperformed the KBr-LiBr-LiCl eutectic and was selected for more extensive testing. Because of their lower melting points and larger liquidi relative to the LiCl-KCl eutectic, the low-melting electrolytes are prime candidates for long-life applications (i.e., for activated lives of one hour or more). This paper will detail the relative performance of the Li(Si)/FeS{sub 2} couple using primarily the LiCl-KCl (standard) eutectic, the LiCl-LiBr-LiF (all-Li) eutectic, and the LiBr-KBr-LiF (low-melting) eutectic electrolytes. Most of the tests were conducted with 5-cell batteries; validation tests were also carried out with appropriate full-sized batteries.

  6. 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.

  7. 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.

  8. Polymer electrolyte-based Li ion batteries for space power

    NASA Astrophysics Data System (ADS)

    Abraham, K. M.; Choe, H. S.; Pasquariello, D. M.

    1997-01-01

    Polyacrylonitrile-based electrolytes have been identified to be appropriate for the fabrication of solid-state Li ion batteries. Prototype battery cells have been fabricated with spinel LiMn2O4 cathode and either a graphite or a petroleum coke anode. Lower capacity fade and longer cycle life were observed in the petroleum coke-based cells. A specific energy of >120 Wh/kg and a cycle life of >500 cycles at the C/3 rate have been demonstrated in these cells. The capacity fade rate in coke/LiMn2O4 cells has been found to be between 0.04 and 0.05% per cycle, about half of that in cells with the graphite anode.

  9. Transport measurement of Li doped monolayer graphene

    NASA Astrophysics Data System (ADS)

    Khademi, Ali; Sajadi, Ebrahim; Dosanjh, Pinder; Folk, Joshua; Stöhr, Alexander; Forti, Stiven; Starke, Ulrich

    Lithium adatoms on monolayer graphene have been predicted to induce superconductivity with a critical temperature near 8 K, and recent experimental evidence by ARPES indicates a critical temperature nearly that high. Encouraged by these results, we investigated the effects of lithium deposited at cryogenic temperatures on the electronic transport properties of epitaxial and CVD monolayer graphene down to 3 K. The change of charge carrier density due to Li deposition was monitored both by the gate voltage shift of the Dirac point and by Hall measurements, in low and high doping regimes. In the high doping regime, a saturation density of 2×1013 cm-2 was observed independent of sample type, initial carrier density and deposition conditions. No signatures of superconductivity were observed down to 3 K.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. First Principles Prediction of Nitrogen-doped Carbon Nanotubes as a High-Performance Cathode for Li-S Batteries

    SciTech Connect

    Wang, Zhiguo; Niu, Xinyue; Xiao, Jie; Wang, Chong M.; Liu, Jun; Gao, Fei

    2013-07-16

    The insulating nature of sulfur and the solubility of the polysulfide in organic electrolyte are two main factors that limit the application of lithium sulfur (Li-S) battery systems. Enhancement of Li conductivity, identification of a strong adsorption agent of polysulfides and the improvement of the whole sulfur-based electrode are of great technological importance. The diffusion of Li atoms on the outer-wall, inner-wall and inter-wall spaces in nitrogen-doped double-walled carbon nanotubes (CNTs) and penetrations of Li and S atoms through the walls are studied using density functional theory. We find that N-doping does not alternate the diffusion behaviors of Li atoms throughout the CNTs, but the energy barrier for Li atoms to penetrate the wall is greatly decreased by N-doping (from ~9.0 eV to ~ 1.0 eV). On the other hand, the energy barrier for S atoms to penetrate the wall remains very high, which is caused by the formation of the chemical bonds between the S and nearby N atoms. The results indicate that Li atoms are able to diffuse freely, whereas S atoms can be encapsulated inside the N-doped CNTs, suggesting that the N-doped CNTs can be potentially used in high performance Li-S batteries.

  15. 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.

  16. 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. PMID:26452054

  17. 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.

  18. 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.

  19. 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.

  20. Potentiometric CO2 Sensor Using Li+ Ion Conducting Li3PO4 Thin Film Electrolyte

    PubMed Central

    Noh, Whyo Sub; Satyanarayana, L.; Park, Jin Seong

    2005-01-01

    Li+ ion conducting Li3PO4 thin film electrolytes with thickness 300nm, 650nm and 1.2μm were deposited on Al2O3 substrate at room temperature by thermal evaporation method. Reference and sensing electrodes were printed on Au interfaces by conventional screen printing technique. The overall dimension of the sensor was 3 × 3 mm and of electrodes were 1 × 1.5 mm each. The fabricated solid state potentiometric CO2 sensors of type: CO2, O2, Au, Li2TiO3-TiO2| Li3PO4 |Li2CO3, Au, CO2, O2 have been investigated for CO2 sensing properties. The electromotive force (emf) and Δemf/dec values of the sensors are dependent on the thickness of the electrolyte film. 1.2μm thickness deposited sensor has shown good sensing behavior than the sensors with less thickness. The Δemf values of the sensor are linearly increased up to 460°C operating temperature and became stable above 460°C. Between 460-500°C temperatures region the sensor has reached an equilibrium state and the experimentally obtained Δemf values are about 80% of the theoretically calculated values. A Nernst's slope of -61mV/decade has been obtained between 250 to 5000 ppm of CO2 concentration at 500°C temperature. The sensor is suitable for ease of mass production in view of its miniaturization and cost effectiveness after some further improvement.

  1. Direct observation of Li diffusion in Li-doped ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Li, Guohua; Yu, Lei; Hudak, Bethany M.; Chang, Yao-Jen; Baek, Hyeonjun; Sundararajan, Abhishek; Strachan, Douglas R.; Yi, Gyu-Chul; Guiton, Beth S.

    2016-05-01

    The direct observation of Li diffusion in Li-doped zinc oxide nanowires (NWs) was realized by using in situ heating in the scanning transmission electron microscope (STEM). A continuous increase of low atomic mass regions within a single NW was observed between 200 °C and 600 °C when heated in vacuum, which was explained by the conversion of interstitial to substitutional Li in the ZnO NW host lattice. A kick-out mechanism is introduced to explain the migration and conversion of the interstitial Li (Lii) to Zn-site substitutional Li (LiZn), and this mechanism is verified with low-temperature (11 K) photoluminescence measurements on as-grown and annealed Li-doped zinc oxide NWs, as well as the observation of an increase of NW surface roughing with applied bias.

  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. 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.

  4. Performance analysis of molten carbonate fuel cell using a Li/Na electrolyte

    NASA Astrophysics Data System (ADS)

    Morita, H.; Komoda, M.; Mugikura, Y.; Izaki, Y.; Watanabe, T.; Masuda, Y.; Matsuyama, T.

    Several years ago, Li/Na carbonate (Li 2CO 3/Na 2CO 3) was developed as the electrolyte of molten carbonate fuel cells (MCFCs) in place of the usual Li/K carbonate (Li 2CO 3/K 2CO 3) to the advantage of a higher ionic conductivity and lower rate of cathode NiO dissolution. To estimate the potential of Li/Na carbonate as the MCFC electrolyte, the dependence of the cell performance on the operating conditions and the behavior during long-term performance was investigated in several bench-scale cell operations. The obtained data on the performance of Li/Na cells was analyzed to estimate the impact of voltage losses by using a performance model and discussed in comparison with the data of conventional Li/K cell performance.

  5. 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

  6. Investigation of the Rechargeability of Li-O2 Batteries in Non-aqueous Electrolyte

    SciTech Connect

    Xiao, Jie; Hu, Jian Z.; Wang, Deyu; Hu, Dehong; Xu, Wu; Graff, Gordon L.; Nie, Zimin; Liu, Jun; Zhang, Jiguang

    2011-07-01

    In order to understand the nature of the limited cycle life and poor energy efficiency associated with the secondary Li-O¬2 batteries the discharge products of primary Li-O2 cells at different depth of discharge (DOD) are systematically analyzed in this work. It is revealed that if discharged to 2.0 V a small amount of Li2O2 coexist with Li2CO3 and RO-(C=O)-OLi) in alkyl carbonate-based electrolyte. Further discharging the air electrodes to below 2.0 V the amount of Li2CO3 and LiRCO3 increases significantly due to the severe electrolyte decomposition. There is no Li2O detected in this alkyl carbonate electrolyte regardless of DOD. It is also found that the alkyl carbonate based electrolyte begins to decompose at 4.0 V during charging under the combined influences from the high surface area carbon, the nickel metal current collector and the oxygen atmosphere. Accordingly the impedance of the Li-O2 cell continues to increase after each discharge and recharge process indicating a repeated plating of insoluble lithium salts on the carbon surface. Therefore the whole carbon electrode becomes completely insulated only after a few cycles and loses the function of providing active tri-phase regions for the Li-oxygen batteries.

  7. Thermal reactions of mesocarbon microbead (MCMB) particles in LiPF 6-based electrolyte

    NASA Astrophysics Data System (ADS)

    Xiao, Ang; Li, Wentao; Lucht, Brett L.

    The thermal reaction of ternary electrolyte (1.0 M LiPF 6 in 1:1:1 ethylene carbonate/dimethyl carbonate/diethyl carbonate) with mesocarbon microbeads (MCMB) particles was investigated by the combined use of NMR, GC-MS, FTIR-ATR, TGA, XPS and SEM/EDS-element map. The thermal decomposition of ternary electrolyte is not inhibited by the presence of MCMB particles. The chemical composition and morphology of the surface of MCMB particles changes significantly upon storage in the presence of ternary electrolyte. Electrolyte decomposition products including oligocarbonates, oligoethylene oxides, polyethylene oxide (PEO), lithium fluorophosphates (Li xPO yF z), and lithium fluoride are deposited on the surface of MCMB particles. The concentration of decomposition products on the surface of MCMB increases with increased storage time and temperature. The addition of dimethyl acetamide (DMAc) impedes the thermal decomposition of the electrolyte and deposition of electrolyte decomposition products on the surface of MCMB.

  8. Pushing the Theoretical Limit of Li-CFx Batteries: A Tale of Bi-functional Electrolyte

    SciTech Connect

    Rangasamy, Ezhiylmurugan; Li, Juchuan; Sahu, Gayatri; Dudney, Nancy J; Liang, Chengdu

    2014-01-01

    In a typical battery, electrodes deliver capacities less or equal the theoretical maxima of the electrode materials.1 The inert electrolyte functions solely as the ionic conductor without contribution to the cell capacity because of its distinct mono-function in the concept of conventional batteries. Here we demonstrate that the most energy-dense Li-CFx battery2 delivers a capacity exceeding the theoretical maximum of CFx with a solid electrolyte of Li3PS4 (LPS) that has dual functions: as the inert electrolyte at the anode and the active component at the cathode. Such a bi-functional electrolyte reconciles both inert and active characteristics through a synergistic discharge mechanism of CFx and LPS. Li3PS4 is known as an inactive solid electrolyte with a broad electrochemical window over 5 V.3 The synergy at the cathode is through LiF, the discharge product of CFx, which activates the electrochemical discharge of LPS at a close electrochemical potential of CFx. Therefore, the solid-state Li-CFx batteries output 126.6% energy beyond their theoretic limits without compromising the stability of the cell voltage. The extra energy comes from the electrochemical discharge of LPS, the inert electrolyte. This bi-functional electrolyte revolutionizes the concept of conventional batteries and opens a new avenue for the design of batteries with an unprecedentedly high energy density.

  9. Characterization of low-melting electrolytes for potential geothermal borehole power supplies: The LiBr-KBr-LiF eutectic

    SciTech Connect

    Guidotti, R.A.; Reinhardt, F.W.

    1998-05-01

    The suitability of modified thermal-battery technology for use as a potential power source for geothermal borehole applications is under investigation. As a first step, the discharge processes that take place in LiSi/LiBr-KBr-LiF/FeS{sub 2} thermal cells were studied at temperatures of 350 C and 400 C using pelletized cells with immobilized electrolyte. Incorporation of a reference electrode allowed the relative contribution of each electrode to the overall cell polarization to be determined. The results of single-cell tests are presented, along with preliminary data for cells based on a lower-melting CsBr-LiBr-KBr eutectic salt.

  10. Stability of the solid electrolyte Li{sub 3}OBr to common battery solvents

    SciTech Connect

    Schroeder, D.J.; Hubaud, A.A.; Vaughey, J.T.

    2014-01-01

    Graphical abstract: The stability of the anti-perovskite phase Li{sub 3}OBr has been assessed in a variety of battery solvents. - Highlights: • Lithium stable solid electrolyte Li{sub 3}OBr unstable to polar organic solvents. • Solvation with no dissolution destroys long-range structure. • Ion exchange with protons observed. - Abstract: Recently a new class of solid lithium ion conductors was reported based on the anti-perovskite structure, notably Li{sub 3}OCl and Li{sub 3}OBr. For many beyond lithium-ion battery uses, the solid electrolyte is envisioned to be in direct contact with liquid electrolytes and lithium metal. In this study we evaluated the stability of the Li{sub 3}OBr phase against common battery solvents electrolytes, including diethylcarbonate (DEC) and dimethylcarbonate (DMC), as well as a LiPF{sub 6} containing commercial electrolyte. In contact with battery-grade organic solvents, Li{sub 3}OBr was typically found to be insoluble but lost its crystallinity and reacted with available protons and in some cases with the solvent. A low temperature heat treatment was able to restore crystallinity of the samples; however evidence of proton ion exchange was conserved.

  11. Preparation of Li3BO3-Li2SO4 glass-ceramic electrolytes for all-oxide lithium batteries

    NASA Astrophysics Data System (ADS)

    Tatsumisago, Masahiro; Takano, Ryohei; Tadanaga, Kiyoharu; Hayashi, Akitoshi

    2014-12-01

    Newly designed oxide glass-ceramic electrolyte of Li2.9B0.9S0.1O3.1 with high Li+ ion conductivity and low melting property was prepared by mechanical milling and subsequent heat treatment at 290 °C. This material showed 1.4 × 10-5 S cm-1 at room temperature and excellent deformation properties to obtain powder-compressed pellets with low interfacial resistance like in the case of sulfide solid electrolytes. The glass-ceramic exhibited favorable mechanical properties to form favorable solid-solid contacts in solid-state batteries by pressing without high temperature heat treatments. All-solid-state In/LiCoO2 cells using these oxide glass-ceramic electrolytes operated as secondary batteries at room temperature.

  12. 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. PMID:25613366

  13. Enhancing blue luminescence from Ce-doped ZnO nanophosphor by Li doping

    PubMed Central

    2014-01-01

    Undoped ZnO, Ce-doped ZnO, and (Li, Ce)-codoped ZnO nanophosphors were prepared by a sol-gel process. The effects of the additional doping with Li ions on the crystal structure, particle morphology, and luminescence properties of Ce-doped ZnO were investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy and photoluminescence spectroscopy. The results indicate that the obtained samples are single phase, and a nanorod shaped morphology is observed for (Li, Ce)-codoping. Under excitation with 325 nm light, Ce-doped ZnO phosphors show an ultraviolet emission, a green emission, and a blue emission caused by Zn interstitials. The spectrum of the sample codoped with a proper Li concentration features two additional emissions that can be attributed to the Ce3+ ions. With the increase of the Li doping concentration, the Ce3+ blue luminescence of (Li, Ce)-codoped ZnO is obviously enhanced, which results not only from the increase of the Ce3+ ion concentration itself but also from the energy transfer from the ZnO host material to the Ce3+ ions. This enhancement reaches a maximum at a Li content of 0.02, and then decreases sharply due to the concentration quench. These nanophosphors may promise for application to the visible-light-emitting devices. PACS 78.55.Et; 81.07.Wx; 81.20.Fw PMID:25258604

  14. Dye-sensitized solar cell comprising polyethyl methacrylate doped with ammonium iodide solid polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Singh, Vivek Kr.; Bhattacharya, B.; Shukla, S.; Singh, Pramod K.

    2014-09-01

    The aim of the present work was to develop a new solid electrolyte polyethyl methacrylate doped with ammonium iodide polymer electrolyte and its application in dye-sensitized solar cell (DSSC). The electrical, structural and photoelectrochemical properties of polymer electrolytes are presented in detail. DSSCs have been fabricated and characterized. The polymer electrolyte film with maximum ionic conductivity shows maximum efficient DSSC of efficiency 0.43 % at 1 sun condition.

  15. Dye-sensitized solar cell comprising polyethyl methacrylate doped with ammonium iodide solid polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Singh, Vivek Kr.; Bhattacharya, B.; Shukla, S.; Singh, Pramod K.

    2015-03-01

    The aim of the present work was to develop a new solid electrolyte polyethyl methacrylate doped with ammonium iodide polymer electrolyte and its application in dye-sensitized solar cell (DSSC). The electrical, structural and photoelectrochemical properties of polymer electrolytes are presented in detail. DSSCs have been fabricated and characterized. The polymer electrolyte film with maximum ionic conductivity shows maximum efficient DSSC of efficiency 0.43 % at 1 sun condition.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    Based on an extensive series of normalized full cell Li/TiS2 cycling studies, open-circuit storage tests, microcalorimetry and AC impedance studies, and chemical precedent, we propose an integrated chemical model consistent with experimental observations concerning the behavior of numerous LiAsF6/cyclic ether electrolytes. The particularly striking potency of certain additives such as 2-methylfuran and the hydroxide action resides in their ability to intercept several different adverse catalytic processes concurrently in the bulk electrolyte as well as the Li anode and TiS2 cathode.

  17. Oxygen-driven transition from two-dimensional to three-dimensional transport behaviour in β-Li3PS4 electrolyte.

    PubMed

    Wang, Xuelong; Xiao, Ruijuan; Li, Hong; Chen, Liquan

    2016-08-01

    Solid state electrolytes with high Li ion conduction are vital to the development of all-solid-state lithium batteries. Lithium thiophosphate Li3PS4 is the parent material of a series of Li superionic conductors Li10MX2S12 (M = Ge, Sn,…; X = P, Si,…), and β-Li3PS4 shows relatively high ionic conductivity itself, though it is not room-temperature stable. The positive effects of introducing O dopants into β-Li3PS4 to stabilize the crystal phase and improve the ionic conducting behaviour are revealed in this study. With the aid of first-principles density functional theory (DFT) computations and quasi-empirical bond-valence calculations, the effects of O doping at different concentrations on the properties of β-Li3PS4 is thoroughly investigated from the aspects of lattice structures, electronic structures, ionic transport properties, the interface stability against Li and the thermodynamic stability. An oxygen-driven transition from two-dimensional to three-dimensional transport behaviour is found and the oxygen dopants play the role as a connector of 2D paths. Based on all these simulation results, hopefully our research can provide a new strategy for the modification of lithium thiophosphate solid electrolytes. PMID:27432279

  18. Improved MCFC performance with Li/Na/Ba/Ca carbonate electrolyte.

    SciTech Connect

    Centeno, C.-J.; Kaun, T. D.; Krumpelt, M.; Schoeler, A.

    1999-07-21

    Earlier electrolyte segregation tests of Li/Na carbonate used chemical analysis such as inductively coupled plasma/atomic emission spectroscopy (ICP/AES) of matrix strips wetted with carbonate and exposed to 5- to 20-V potential gradients. A segregation factor was correlated to the Li/Na carbonate composition. While fairly substantial segregation occurs at the eutectic composition of 52% Li, it is minimal at 60% to 75% Li. Such lithium-rich Li/Na carbonates may not be practical because the melting points are too high (i.e., liquidus point is 625 C). By adding calcium and barium to the lithium/sodium carbonates, we were able to lower the melting point and maintain nonsegregating behavior. This work is directed at examining the long-term stability of the quaternary Li/Na/Ba/Ca electrolytes. Electrolyte optimization work evaluates Li/Na ratio and Ba/Ca level to improve cell performance at 320 mA/cm{sup 2} and reduce temperature sensitivity. A number of cells with quaternary Li/Na/Ba/Ca electrolytes ranging from 3 to 5% Ba/Ca have operated well with stable, long-term performance. Congruent melting carbonate is important for commercial development. The best so far is 3.5% Ba/Ca/Na/Li (3.5 mol%/3.5 mol% Ba/Ca) carbonate (m.p. 440 C). Performance at 160 mA/cm{sup 2} is increased up to 150mV as compared with the baseline cell containing the Li/Na eutectic composition. Life stability has been reproduced by a number of bench-scale MCFC test with operations of 2000-4300 h and the electrolyte composition across the matrix little changed.

  19. 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.

  20. Structure and Stoichiometry in Supervalent Doped Li7La3 Zr2O12

    DOE PAGESBeta

    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,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

  1. 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.

  2. 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.

  3. Efficient method for Li doping of α-rhombohedral boron

    NASA Astrophysics Data System (ADS)

    Dekura, H.; Shirai, K.; Yanase, A.

    2011-09-01

    Li doping is a promising method for achieving metallization of α-rhombohedral boron (α-boron for short), which is a potential candidate for a high-Tc superconducting material. Toward this end, a serious drawback has been the difficulty of doping α-boron, even though there are theoretical predictions claiming that it should be easy. This discrepancy has been systematically studied by the ab initio pseudopotential method through calculations of various structural and phonon properties of the material. For this study, a comparison with β-boron is important because experimental data are available in this case. The present results demonstrate that while Li doping is difficult for α-boron under normal conditions, it is easy for β-boron, which is completely consistent with experiments. The difference between these crystals originates from the contrasting characteristics of the bonding. For α-boron, the bonding requirement of the host crystal is fulfilled so well that the only way for a Li atom to enter the crystal is through the antibonding states. Electronically, this is favorable because it causes an almost perfect rigid-band shift without modifying the bonding nature of the host crystal. In terms of structural effects, Li doping causes a slight decrease in the cell angle αrh as well as softening of the elastic properties. A striking effect of Li doping is manifested in substantial phonon softening of the librational mode. These changes can be regarded as reliable criteria for the experimental detection of Li inclusion. On the other hand, β-boron can be characterized as a frustrated system, and the crystal has a propensity to welcome guest atoms in order to eliminate ill-connected bonds. As a result, even though Li is easily incorporated into β-boron, the carriers are not activated for electrical conduction. The remaining problem is how to overcome the difficulty of Li doping of α-boron. The most important contribution of this study lies in demonstrating the

  4. 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.

  5. 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.

  6. Thermal process dependence of Li configuration and electrical properties of Li-doped ZnO

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Knutsen, K. E.; Merz, T.; Kuznetsov, A. Yu.; Svensson, B. G.; Brillson, L. J.

    2012-01-01

    We used depth-resolved cathodoluminescence spectroscopy (DRCLS) to describe the strong dependence of Li acceptor formation on thermal treatment in Li-doped ZnO. Within a 500-600 °C annealing temperature range, subsequent quenching ZnO leaves Li as interstitial donors, resulting in low room temperature resistivity, while slow cooling in air allows these interstitials to fill Zn vacancies forming Li acceptors 3.0 eV below the conduction band edge. DRCLS reveals an inverse relationship between the optical emission densities of lithium on zinc sites versus zinc vacancy sites, demonstrating the time dependence of Li interstitials to combine with zinc vacancies in order to form substitutional Li acceptors.

  7. Studies on the enhancement of solid electrolyte interphase formation on graphitized anodes in LiX-carbonate based electrolytes using Lewis acid additives for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Li, L. F.; Xie, B.; Lee, H. S.; Li, H.; Yang, X. Q.; McBreen, J.; Huang, X. J.

    The new electrolyte systems utilizing one type of Lewis acids, the boron based anion receptors (BBARs) with LiF, Li 2O, or Li 2O 2 in carbonate solutions have been developed and reported by us. These systems open up a new approach in developing non-aqueous electrolytes with higher operating voltage and less moisture sensitivity for lithium-ion batteries. However, the formation of a stable solid electrolyte interphase (SEI) layer on the graphitized anodes is a serious problem needs to be solved for these new electrolyte systems, especially when propylene carbonate (PC) is used as a co-solvent. Using lithium bis(oxalato)borate (LiBOB) as an additives, the SEI layer formation on mesophase carbon microbeads (MCMB) anode is significantly enhanced in these new electrolytes containing boron-based anion receptors, such as tris(pentafluorophenyl) borane, and lithium salt such as LiF, or lithium oxides such as Li 2O or Li 2O 2 in PC and dimethyl carbonate (DMC) solvents. The cells using these electrolytes and MCMB anodes cycled very well and the PC co-intercalation was suppressed. Fourier transform infrared spectroscopy (FTIR) studies show that one of the electrochemical decomposition products of LiBOB, lithium carbonate (Li 2CO 3), plays a quite important role in the stablizing SEI layer formation.

  8. Control of Li configuration and electrical properties of Li-doped ZnO

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Knutsen, K. E.; Merz, T.; Kuznetsov, A. Yu; Svensson, B. G.; Brillson, L. J.

    2012-09-01

    Li-doped ZnO after different thermal treatments was characterized by depth-resolved cathodoluminescence spectroscopy (DRCLS), secondary ion mass spectrometry, surface photovoltage spectroscopy (SPS), coupled with other surface science techniques. It is found that the Li configuration and electrical properties of Li-doped ZnO could be controlled by different thermal processes. Within a 500-600 °C annealing temperature range, subsequent quenching of ZnO leaves Li as interstitial donors, resulting in n-type low room temperature resistivity. In contrast, slower cooling in air enables these interstitials to fill Zn vacancies, forming Li acceptors 3.0 eV below the conduction band edge. Emergence of this acceptor and the resultant resistivity increase agree with the calculated diffusion lengths based on published diffusion coefficients. In general, these acceptors are compensated by residual intrinsic and extrinsic donors, resulting in a semi-insulating material. DRCL spectra exhibit a 3.0 eV optical signature of the LiZn acceptor and its depth distribution in slow-cooled ZnO. A 3.0 eV SPS absorption feature corresponding to a conduction band-to-acceptor level transition confirms this acceptor assignment. Nanoscale SPS spectra reveal p-type band bending localized near ZnO surface nano-mounds, where VZn and LiZn acceptor densities increase. The slow-cooled and quenched Li-doped ZnO spectra display an inverse relationship between the optical emission densities of lithium on zinc versus zinc vacancy sites, demonstrating the time dependence of Li interstitial diffusion to reach zinc vacancies and form substitutional Li acceptors.

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

    PubMed

    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

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    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.

  12. 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.

  13. 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.

  14. First-Principles Characterization of the Unknown Crystal Structure and Ionic Conductivity of Li7P2S8I as a Solid Electrolyte for High-Voltage Li Ion Batteries.

    PubMed

    Kang, Joonhee; Han, Byungchan

    2016-07-21

    Using first-principles density functional theory calculations and ab initio molecular dynamics (AIMD) simulations, we demonstrate the crystal structure of the Li7P2S8I (LPSI) and Li ionic conductivity at room temperature with its atomic-level mechanism. By successively applying three rigorous conceptual approaches, we identify that the LPSI has a similar symmetry class as Li10GeP2S12 (LGPS) material and estimate the Li ionic conductivity to be 0.3 mS cm(-1) with an activation energy of 0.20 eV, similar to the experimental value of 0.63 mS cm(-1). Iodine ions provide an additional path for Li ion diffusion, but a strong Li-I attractive interaction degrades the Li ionic transport. Calculated density of states (DOS) for LPSI indicate that electrochemical instability can be substantially improved by incorporating iodine at the Li metallic anode via forming a LiI compound. Our methods propose the computational design concept for a sulfide-based solid electrolyte with heteroatom doping for high-voltage Li ion batteries. PMID:27345207

  15. 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.

  16. Quantum chemical treatment of Li/Li+ doped defected carbon nanocapsules

    NASA Astrophysics Data System (ADS)

    Peköz, Rengin; Erkoç, Şakir

    2008-06-01

    Structural and electronic properties of nLi and nLi+ ( n=1-3) doped mono-vacancy defected carbon nanocapsule (CNC) systems have been investigated theoretically by performing semi-empirical self-consistent-field (SCF) molecular orbital (MO) and density functional theory (DFT) methods. Semi-empirical SCF MO method at PM3 level has been considered to optimize fully the geometry of the CNCs in their ground states. The total energies of these structures were calculated using B3LYP exchange-correlation functional in DFT method with 6-31G basis set. The studied systems include nLi/nLi+ doped (5,5) and (9,0) single-walled CNCs with mono-atom vacancies. The molecular properties, energies, some selected MO eigenvalues and dipole moments of the studied capsules have been reported. Furthermore, molecular dynamics simulations have been performed to study the structural properties and energetics of nLi/nLi+ doped mono-vacancy defected CNCs.

  17. Patternable gel electrolyte infiltrated into all-solid porous Li-ion electrodes

    NASA Astrophysics Data System (ADS)

    Sun, Ke; Dillon, Shen J.

    2014-06-01

    Gel electrolyte based on 1M LiPF6 in ethylene carbonate:dimethyl carbonate, polyethyleneglycol diacrylate oligomer, and 2,2'-azobis(2-methylpropionitrile) is infiltrated into porous sintered LiCoO2 electrodes and cured in situ. The associated batteries function well, which is consistent with microscopy observations indicating that the gel electrolyte penetrates the electrode well and wets to the electrode particles. Trimethyl silyl acrylate is used to functionalize glass substrates and will cross link with polyethyleneglycol diacrylate during curing to promote bonding between the substrate and the gel electrolyte. The functionalization can localize adhesion allowing the electrolyte to easily release from unfunctionalized glass, which can be used as a mold.

  18. Experimental Studies on (PVC+LiCIO4+DMP) Polymer Electrolyte Systems for Lithium Battery

    NASA Astrophysics Data System (ADS)

    Subba Reddy, Ch. V.; Qi, Y. Y.; Zhu, Q. Y.; Liu, H. X.; Zhao, X. J.; Chen, W.

    2006-06-01

    Poly (vinyl chloride)(PVC)-based solid polymer electrolyte films with LiClO4+plasticizer (dimethyl phthalate) have been prepared by the solution -cast technique. Various experimental techniques have been used, such as X-ray diffraction (XRD) and infrared spectroscopy (IR), a.c. impedance spectroscopy and transport number measurements, to characterize these polymer electrolyte films. The complexation has been confirmed from XRD and IR studies. A maximum room temperature conductivity (1.1 × 10-4S/cm) has been observed for (PVC+LiClO4+DMP)(20:5:75) complex. The temperature dependent conductivity plots show Arrhenius behaviour. The activation energy is estimated and the results are discussed. The transference number data indicated that the conducting species in these electrolytes are the anions. Using this electrolyte, electrochemical cells are fabricated and their discharge profiles are studied under constant load.

  19. 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

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

    PubMed

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

    2012-10-01

    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. Compared with the AC/S composite, the NC/S composite showed enhanced activity toward sulfur reduction, as evidenced by the lower onset sulfur reduction potential, higher redox current density in the CV test, and faster charge-transfer kinetics, as indicated by EIS measurements. At room temperature under a current density of 84 mA g(-1) (C/20), the battery based on the NC/S composite exhibited a higher discharge potential and an initial capacity of 1420 mAh g(-1), whereas the battery based on the AC/S composite showed a 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; capacity fading can be improved by further cathode modification. PMID:22847977

  1. 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.

  2. 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.

  3. 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

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

    PubMed

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

    2016-08-21

    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. PMID:27455404

  5. Ferromagnetism in Li doped ZnO nanoparticles: The role of interstitial Li

    NASA Astrophysics Data System (ADS)

    Ullah Awan, Saif; Hasanain, S. K.; Bertino, Massimo F.; Hassnain Jaffari, G.

    2012-11-01

    ZnO nanoparticles doped with Li (Zn1-yLiyO, y ≤ 0.1) have been investigated with emphasis on the correlation between their magnetic, electronic, and structural properties. In particular, defects such as interstitial Li and Zn atoms, substitutional Li atoms, and oxygen vacancies have been identified by X-ray photoelectron spectroscopy (XPS) and their respective roles in stabilization of the magnetic moment are discussed. X-ray diffraction (XRD) and XPS give clear evidence of Li presence at both substitutional and interstitial sites. XPS studies further show that the amount of substitutional Li defects (Lizn) and interstitial Li defects (Lii) vary non-monotonically with the Li concentration, with the Lii defects being noticeably high for the y = 0.02, 0.08, and 0.10 concentrations, in agreement with the XRD results. Magnetization studies show room temperature ferromagnetism in these nanoparticles with the moment being largest for the particles with high concentration of interstitial lithium and vice versa. Both interstitial Zn (Zni) defects and Zn-O bonds were determined from the Zn LMM Auger peaks; however, the variation of these with Li concentrations was not large. Oxygen vacancies (Vo) concentrations are estimated to be relatively constant over the entire Li concentration range. We relate the Lii and Zni defects to the formation and stabilization of Zn vacancies and thus stabilizing the p-type ferromagnetism predicted for cation (zinc) vacancy in the ZnO type oxides.

  6. 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).

  7. 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.

  8. 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.

  9. The partially reversible formation of Li-metal particles on a solid Li electrolyte: applications toward nanobatteries

    NASA Astrophysics Data System (ADS)

    Arruda, Thomas M.; Kumar, Amit; Kalinin, Sergei V.; Jesse, Stephen

    2012-08-01

    The feasibility of large-scale implementation of Li-air batteries (LABs) hinges on understanding the thermodynamic and kinetic factors that control charge-discharge rates, efficiency and life times. Here, the kinetics of bias-induced reactions is explored locally on the surface of Li-ion conductive glass ceramics, a preferred electrolyte for LABs, using direct current-voltage and strain spectroscopies. Above a critical bias, particle growth kinetics were found to be linear in both the bias and time domains. Partial reversibility was observed for Li particles as evidenced by the presence of anodic peaks following the Li+ reduction, as well an associated reduction in particle height. The degree of reversibility was highest for the smallest particles formed. These observations thus suggest the possibility of producing nanobatteries with an active anode volume of the order of 0.1 al.

  10. The partially reversible formation of Li-metal particles on a solid Li electrolyte: applications toward nanobatteries

    SciTech Connect

    Arruda, Thomas M; Kumar, Amit; Kalinin, Sergei V; Jesse, Stephen

    2012-01-01

    The feasibility of large-scale implementation of Li-air batteries (LABs) hinges on understanding the thermodynamic and kinetic factors that control charge-discharge rates, efficiency and life times. Here, the kinetics of bias-induced reactions is explored locally on the surface of Li-ion conductive glass ceramics, a preferred electrolyte for LABs, using direct current-voltage and strain spectroscopies. Above a critical bias, particle growth kinetics were found to be linear in both the bias and time domains. Partial reversibility was observed for Li particles as evidenced by the presence of anodic peaks following the Li{sup +} reduction, as well an associated reduction in particle height. The degree of reversibility was highest for the smallest particles formed. These observations thus suggest the possibility of producing nanobatteries with an active anode volume of the order of 0.1 al.

  11. The behavior of MCFCs using Li/K and Li/Na carbonates as the electrolyte at high pressure

    SciTech Connect

    Yoshikawa, M.; Mugikura, Y.; Watanabe, T.; Ota, T.; Suzuki, A.

    1999-08-01

    High operating pressure, about 12--25 atm, is required to develop a highly efficient molten carbonate fuel cell (MCFC) plant system combined with a gas turbine or coal gasifier system. Operation at high pressure, over 10 atm, will accelerate dissolution of the NiO cathode and shorten cell life. Therefore, economical applicability as a high-pressure and high-efficiency MCFC plant system and the economical requirement of cell life time must be totally investigated. It is very important to clarify the performance of the MCFC under such high pressures as the first step for such an investigation. The authors have examined the performance of several MCFC cells using Li/K and Li/Na electrolyte at pressures of up to 44.5 atm, avoiding possible carbon formation in the fuel stream. The analysis method for cell performance developed below 7 atm pressure conditions has proved applicable for analyzing cell performance over 10 atm. The smaller cathode polarization concerned with CO{sub 2} concentration and the higher conductivity of the Li/Na electrolyte enabled a higher performance than that of a Li/K cell. Application of the Li/Na electrolyte to MCFCs seems to be an effective way of prolonging cell life with measurements of the small amount of deposited nickel. Furthermore, the Li/Na cell attained 3.3 kW/m{sup 2} power density, and a high cell voltage (0.82 V) was obtained at 400 mA/cm{sup 2} in 16 atm. This result shows the possibility of developing a high-efficiency MCFC plant system.

  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. 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.

  14. 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.

  15. Application of LiBOB-based liquid electrolyte in co-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Jun, H. K.; Buraidah, M. H.; Noor, M. M.; Kufian, M. Z.; Majid, S. R.; Sahraoui, B.; Arof, A. K.

    2013-11-01

    Co-sensitized solar cells have been fabricated using metal complex N3 dye and Ag2S/CdS quantum dots coupled with LiBOB-based liquid electrolyte. Quantum dots (QDs) were synthesized via the successive ionic layer adsorption and reaction (SILAR) route. The absorbance and band gap energy of Ag2S and CdS QDs were determined. Their refractive indices were observed to be in the range of 1.5175-1.5200. It has been shown that LiBOB-based liquid electrolyte is able to function in the QD/N3 dye co-sensitized solar cells but some stability issues of the QD were observed in the electrolyte system containing iodide whereby the QD-sensitized TiO2 was easily etched. Overall efficiencies and fill factors of the co-sensitized solar cells varied from 0.98% to 1.66% and 40% to 46% respectively. CdS QD was shown to be effective when coupled with polysulfide electrolyte while Ag2S QD was favorable towards the LiBOB-based liquid electrolyte.

  16. Effect of electrolytes on the structure and evolution of the solid electrolyte interphase (SEI) in Li-ion batteries: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Pil; Duin, Adri C. T. van; Shenoy, Vivek B.

    2011-10-01

    We have studied the formation and growth of solid-electrolyte interphase (SEI) for the case of ethylene carbonate (EC), dimethyl carbonate (DMC) and mixtures of these electrolytes using molecular dynamics simulations. We have considered SEI growth on both Li metal surfaces and using a simulation framework that allows us to vary the Li surface density on the anode surface. Using our simulations we have obtained the detailed structure and distribution of different constituents in the SEI as a function of the distance from the anode surfaces. We find that SEI films formed in the presence of EC are rich in Li2CO3 and Li2O, while LiOCH3 is the primary constituent of DMC films. We find that dilithium ethylene dicarbonate, LiEDC, is formed in the presence of EC at low Li surface densities, but it quickly decomposes to inorganic salts during subsequent growth in Li rich environments. The surface films formed in our simulations have a multilayer structure with regions rich in inorganic and organic salts located near the anode surface and the electrolyte interface, respectively, in agreement with depth profiling experiments. Our computed formation potentials 1.0 V vs. Li/Li+ is also in excellent accord with experimental measurements. We have also calculated the elastic stiffness of the SEI films; we find that they are significantly stiffer than Li metal, but are somewhat more compliant compared to the graphite anode.

  17. 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.

  18. 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.

  19. 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

  20. N-methyl-2-pyrrolidone as a solvent for the non-aqueous electrolyte of rechargeable Li-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Xie, Kai; Wang, Lingyan; Han, Yu

    2012-12-01

    The instability of solvent molecules toward oxygen reduction species is the main reason for the performance deterioration of rechargeable Li-air batteries. Identifying the appropriate electrolyte solvents is one prerequisite for the application of Li-air batteries. In this article, we study N-methyl-2-pyrrodione (NMP) as a solvent for the non-aqueous electrolyte of Li-air batteries. Oxygen reduction reactions (ORRs) and oxygen oxidation reactions (OERs) are investigated on Au and glassy carbon (GC) electrodes in NMP-based terabutylammonium perchlorate (TBAClO4) and lithium perchlorate (LiClO4) electrolyte solutions using the cyclic voltammetry method. Raman and X-ray photoemission spectra (XPS) are used to detect the species on the electrode surface during cell cycles. The results show that while the one-electron O2/O2- reversible couples are observed in TBAClO4/NMP, in presence of Li ion, the initially formed LiO2 generated by one-electron transfer process decomposes to Li2O2. As the predominant discharge products, Li2O2 decomposes during the recharge processes. The cells using NMP-based electrolytes exhibit good cycle performance, and the first cycle efficiency is approximately 97%. Although the decomposition of NMP occurs on the air electrode surface during the cells recharge, the increased chemical stability against oxygen reduction species offer NMP-based electrolytes as potential candidates for rechargeable Li-air batteries electrolytes.

  1. 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

  2. A new look at the solid electrolyte interphase on graphite anodes in Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Edström, Kristina; Herstedt, Marie; Abraham, Daniel P.

    The solid electrolyte interphase (SEI) of graphite electrodes has been extensively studied using surface sensitive techniques such as photoelectron spectroscopy (PES) and soft X-ray spectroscopy. By combining measurements of reference compounds with graphite electrodes cycled in different electrolytes and under different conditions, knowledge of the solid electrolyte interphase (SEI) chemistry can be obtained. In this article, conclusive results concerning the chemical composition of the inorganic part of the SEI is described. The results show that Li 2O often reported to be present in the SEI could be an artifact from abusive Ar + sputtering. The presence of Li 2CO 3 is a matter of debate; the compound is not observed in anodes extracted from hermetically sealed cells that are never exposed to air. The results show that cell-design and sample handling are crucial to the observed chemical composition of the SEI.

  3. 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.

  4. 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.

  5. Reversible lithium intercalation in a lithium-rich layered rocksalt Li2RuO3 cathode through a Li3PO4 solid electrolyte

    NASA Astrophysics Data System (ADS)

    Zheng, Yueming; Hirayama, Masaaki; Taminato, Sou; Lee, Soyeon; Oshima, Yoshifumi; Takayanagi, Kunio; Suzuki, Kota; Kanno, Ryoji

    2015-12-01

    Li2RuO3 (001) films with a lithium-rich layered rocksalt structure are epitaxially grown on a Al2O3(0001) substrate through pulsed laser deposition, followed by stacking of an amorphous Li3PO4 solid electrolyte. A half solid-state battery with a Li3PO4/Li2RuO3 cathode, liquid electrolyte, and lithium anode exhibits two redox peak pairs at 3.4 and 3.6 V, demonstrating lithium intercalation in the Li2RuO3 through the Li3PO4 solid electrolyte. All-solid-state batteries are fabricated by Li or In metal anode deposition on the Li3PO4/Li2RuO3. The Li/Li3PO4/Li2RuO3 cell delivers an initial discharge capacity of 101 mAh g-1, which does not fade significantly over 30 cycles. Furthermore, the Li2RuO3 rate capability is comparable to that of a liquid-type battery. Lithium-rich layered materials are available for use as cathodes in all-solid-state batteries.

  6. UCN detection with 6Li-doped glass scintillators

    NASA Astrophysics Data System (ADS)

    Ban, G.; Bodek, K.; Lefort, T.; Naviliat-Cuncic, O.; Pierre, E.; Plonka, C.; Rogel, G.

    2009-12-01

    We report the results of test measurements aimed at determining the performance of 6Li-doped glass scintillators for ultra-cold neutron detection. Investigations have mainly focused on the reduction of the gamma-ray sensitivity of the scintillators. The probability of gamma interaction has been considerably lowered using very thin glasses. For signals corresponding to full-energy deposition, a background count rate of 8×10 -3 s -1 was obtained for a shielded 0.5 cm 3 GS10 scintillator located near the PF2 turbine at ILL. The neutron-gamma separation has further been improved using a stack with an 6Li-depleted scintillator and an 6Li-enriched one. Neutron captures leading to partial energy deposition (so-called "edge events") have strongly been reduced resulting in a clear separation between the neutron and the gamma contributions.

  7. 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.

  8. 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.

  9. Power capability of LiTDI-based electrolytes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Paillet, Sabrina; Schmidt, Gregory; Ladouceur, Sébastien; Fréchette, Joël; Barray, Francis; Clément, Daniel; Hovington, Pierre; Guerfi, Abdelbast; Vijh, Ashok; Cayrefourcq, Ian; Zaghib, Karim

    2015-10-01

    We report results obtained with lithium 4,5-dicyano-2-(trifluoromethyl) imidazolide (LiTDI), which we believe is a promising lithium salt for electrolytes in lithium-ion batteries. This "Hückel"- type salt has high charge delocalizations which contribute to good lithium-ion dissociation. In addition, it has high thermal stability and safer degradation products compared to LiPF6, which were identified by TGA-MS. It also does not corrode but passivate the aluminum current collector. Cyclic voltammetry measurements showed a stability up to 4.5 V, which is sufficient for use with standard cathode materials. The power capability of half cells containing LiTDI in EC/DEC was evaluated with standard cathodes used in lithium-ion batteries: LFP, NMC, LCO and LMO. Two LiTDI concentrations were investigated: 1 M and 0.6 M and compared with a reference electrolyte: 1 M LiPF6. In spite of a slightly lower conductivity than the LiPF6, LiTDI (1 M and 0.6 M) shows similar power capability up to 2C with LFP (84% of specific capacity recovered), 10C with NMC (61% of specific capacity recovered), and up to 20C for LMO (88% of specific capacity recovered). Furthermore, better power capability was obtained with 0.6 M LiTDI with LCO, which yielded 82% of specific capacity recovered at 1C (67% for 1 M LiTDI and 1 M LiPF6).

  10. Compatibility of lithium difluoro(sulfato)borate-based electrolyte for LiMn2O4 cathode

    NASA Astrophysics Data System (ADS)

    Li, Shiyou; Liu, Jinliang; Li, Lingxia; Li, Xiaopeng; Jing, Jie; Cui, Xiaoling

    2015-03-01

    Lithium difluoro(sulfato)borate (LiBF2SO4) is investigated as a lithium salt for non-aqueous electrolytes for LiMn2O4 cathode in lithium-ion batteries. Inductively coupled plasma-atomic emission spectrometry analysis is used to analyze the Mn dissolution. Scanning electron microscopy and AC impedance measurements analysis are used to analyze the formation of the surface film on the surface of LiMn2O4 cathode. These results demonstrate that LiBF2SO4-based electrolyte favourably facilitates the formation of an effective and conductive interface film on the cathode surface to improve the stabilization of cathode/electrolyte interface. Besides, LiMn2O4 cells using LiBF2SO4-based electrolyte exerts several advantages, such as stable cycling performance, low cell impedance, low polarization resistance, and good rate performance. It suggests that LiBF2SO4-based electrolyte has good compatibility with LiMn2O4 cathode, and LiBF2SO4 would be a very promising lithium salt for LiMn2O4 cathode in lithium-ion batteries.

  11. 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.

  12. Electrochemical quartz crystal microbalance measurement of a Li4Ti5O12 composite electrode in a carbonate electrolyte

    NASA Astrophysics Data System (ADS)

    Serizawa, Nobuyuki; Shono, Kumi; Kobayashi, Yo; Miyashiro, Hajime; Katayama, Yasushi; Miura, Takashi

    2015-11-01

    Electrochemical quartz crystal microbalance (EQCM) measurement is conducted with a Li4Ti5O12 (lithium titanium oxide, LTO)-coated quartz crystal electrode in a carbonate electrolyte (ethylene carbonate + dimethyl carbonate; 50: 50 vol%) containing 1 M LiPF6. In-situ monitoring of the mass change during the charge and discharge of the LTO electrode can be achieved quantitatively because of the "zero-strain" property of LTO with Li+ insertion and the probably low reactivity between LTO and the electrolyte. The local changes of viscosity and density of the electrolyte contacting the LTO electrode are detected via the resonance resistance of the quartz crystal electrode, suggesting the local concentrations of Li+ and counter anion changed significantly during insertion and extraction of Li+ in the organic electrolyte.

  13. Enhanced deposition of ZnO films by Li doping using radio frequency reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Chen, Liang-xian; Liu, Sheng; Li, Cheng-ming; Wang, Yi-chao; Liu, Jin-long; Wei, Jun-jun

    2015-10-01

    Radio frequency (RF) reactive magnetron sputtering was utilized to deposit Li-doped and undoped zinc oxide (ZnO) films on silicon wafers. Various Ar/O2 gas ratios by volume and sputtering powers were selected for each deposition process. The results demonstrate that the enhanced ZnO films are obtained via Li doping. The average deposition rate for doped ZnO films is twice more than that of the undoped films. Both atomic force microscopy and scanning electron microscopy studies indicate that Li doping significantly contributes to the higher degree of crystallinity of wurtzite-ZnO. X-ray diffraction analysis demonstrates that Li doping promotes the (002) preferential orientation in Li-doped ZnO films. However, an increase in the ZnO lattice constant, broadening of the (002) peak and a decrease in the peak integral area are observed in some Li-doped samples, especially as the form of Li2O. This implies that doping with Li expands the crystal structure and thus induces the additional strain in the crystal lattice. The oriented-growth Li-doped ZnO will make significant applications in future surface acoustic wave devices.

  14. 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.

  15. Electrode-electrolyte interface in Li-ion batteries: current understanding and new insights.

    PubMed

    Gauthier, Magali; Carney, Thomas J; Grimaud, Alexis; Giordano, Livia; Pour, Nir; Chang, Hao-Hsun; Fenning, David P; Lux, Simon F; Paschos, Odysseas; Bauer, Christoph; Maglia, Filippo; Lupart, Saskia; Lamp, Peter; Shao-Horn, Yang

    2015-11-19

    Understanding reactions at the electrode/electrolyte interface (EEI) is essential to developing strategies to enhance cycle life and safety of lithium batteries. Despite research in the past four decades, there is still limited understanding by what means different components are formed at the EEI and how they influence EEI layer properties. We review findings used to establish the well-known mosaic structure model for the EEI (often referred to as solid electrolyte interphase or SEI) on negative electrodes including lithium, graphite, tin, and silicon. Much less understanding exists for EEI layers for positive electrodes. High-capacity Li-rich layered oxides yLi2-xMnO3·(1-y)Li1-xMO2, which can generate highly reactive species toward the electrolyte via oxygen anion redox, highlight the critical need to understand reactions with the electrolyte and EEI layers for advanced positive electrodes. Recent advances in in situ characterization of well-defined electrode surfaces can provide mechanistic insights and strategies to tailor EEI layer composition and properties. PMID:26510477

  16. 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

  17. 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. PMID:27549204

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

    DOE PAGESBeta

    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 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

  19. 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. PMID:26249807

  20. 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.

  1. 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%).

  2. Solvation structure around the Li(+) ion in succinonitrile-lithium salt plastic crystalline electrolytes.

    PubMed

    Shen, Yuneng; Deng, Gang-Hua; Ge, Chuanqi; Tian, Yuhuan; Wu, Guorong; Yang, Xueming; Zheng, Junrong; Yuan, Kaijun

    2016-06-01

    Herein, we discuss the study of solvation dynamics of lithium-succinonitrile (SN) plastic crystalline electrolytes by ultrafast vibrational spectroscopy. The infrared absorption spectra indicated that the CN stretch of the Li(+) bound and unbound succinonitrile molecules in a same solution have distinct vibrational frequencies (2276 cm(-1)vs. 2253 cm(-1)). The frequency difference allowed us to measure the rotation decay times of solvent molecules bound and unbound to Li(+) ion. The Li(+) coordination number of the Li(+)-SN complex was found to be 2 in the plastic crystal phase (22 °C) and 2.5-3 in the liquid phase (80 °C), which is independent of the concentration (from 0.05 mol kg(-1) to 2 mol kg(-1)). The solvation structures along with DFT calculations of the Li(+)-SN complex have been discussed. In addition, the dissociation percentage of lithium salt was also determined. In 0.5 mol kg(-1) LiBF4-SN solutions at 80 °C, 60% ± 10% of the salt dissociates into Li(+), which is bound by 2 or 3 solvent molecules. In the 0.5 mol kg(-1) LiClO4-SN solutions at 80 °C, the salt dissociation ratio can be up to 90% ± 10%. PMID:27189266

  3. Favorable combination of positive and negative electrode materials with glyme-Li salt complex electrolytes in lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Orita, A.; Kamijima, K.; Yoshida, M.; Dokko, K.; Watanabe, M.

    Tetraglyme (G4)-lithium bis(trifluoromethanesulfonyl)amide (TFSA) complexes with different G4 ratio were investigated. An increase in the amount of G4 led to the decrease in the viscosity, and increase in the ionic conductivity of the complex, and G4-LiTFSA showed higher thermal stabilities than the conventional organic electrolyte, when the molar ratio of G4 was more than 40 mol%. The increase in the G4 amount improved the rate capabilities of Li/LiCoO 2 cells in the range where the molar ratio of G4 was between 40 mol% and 60 mol%. The stable Li ion intercalation-deintercalation was not observed in the Li/graphite cell of [Li(G4)][TFSA] (G4: 50 mol%) without additives. However, the additives for forming solid electrolyte interface (SEI) film, such as vinylene carbonate, vinylethylene carbonate, and 1,3-propane sultone, led to the charge-discharge performance comparable to that of the conventional organic electrolyte. The adoption of Li 4Ti 5O 12 and LiFePO 4 led to excellent reversibilities of the Li half cells using [Li(G4)][TFSA], probably because of the favorable operation voltage. In the case of the LiFePO 4/Li 4Ti 5O 12 cell, the cell with [Li(G4)][TFSA] showed the better rate capability than that with the conventional organic electrolyte, when the rate was less than 1 CmA, and it is concluded that [Li(G4)][TFSA] can be the candidate as the alternative of organic electrolytes when the most appropriate electrode-active materials are used.

  4. Li conductivity in siloxane-based polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Stacy, Eric; Fan, Fei; Feng, Hongbo; Gainaru, Catalin; Mays, Jimmy; Sokolov, Alexei

    Polymer electrolytes containing lithium ions are ideal candidates for electrochemical devices and energy storage applications. Understanding their ionic transport mechanism is the key for rational designing of highly conductive polymer matrices. Complementing dielectric spectroscopy investigations by results from rheology and differential scanning calorimetry we focused on the interplay between dynamics of lithium ions and the polymer matrix based on polysiloxane backbone. Our results demonstrate that the conductivity and the degree of decoupling between ion dynamics and structural relaxation depend strongly not only on the ions concentration, but also on the polarity and size of the polymeric side-groups. Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.

  5. A method for treating electrolyte to remove Li{sub 2}O

    SciTech Connect

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

    1998-04-01

    Electrorefining has been used in processes for recovering uranium and plutonium metals from spent nuclear fuel. The electrorefining is performed in an electrochemical cell in which the chopped fuel elements from the reactor forms the anode, the electrolyte, preferably, is the fused eutectic salt of the LiCl-KCl which contain UCl{sub 3} and PuCl{sub 3}. Purified metal collected at the cathode collects at the bottom of the cell. This invention provides a method for removing lithium oxide from the electrolyte salt, with the end formation of a solid lithium-aluminium alloy.

  6. 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.

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

    PubMed

    Yi, Jin; Zhou, Haoshen

    2016-09-01

    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. PMID:27487523

  8. 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.

  9. Characterization of high-voltage cathodes in CsBr-LiBr-KBr eutectic electrolyte

    SciTech Connect

    GUIDOTTI,RONALD A.; REINHARDT,FREDERICK W.

    2000-04-20

    The transition-metal oxides LiMn{sub 2}O{sub 4}, MnO{sub 2}, CrO{sub 2}, and LiCoO{sub 2} were evaluated for possible use as high-voltage cathodes for potential geothermal power applications. These were coupled with Li(Si) anodes and a low-melting CsBr-LiBr-KBr eutectic electrolyte that melts at 228.5 C. Single-cell tests at 250 C and 300 C at 15.8 and 31.6 mA/cm{sup 2} showed that MnO{sub 2} performed the best overall and had the lowest polarization. A 5-cell battery test using LiMn{sub 2}O{sub 4} cathodes was only modestly successful due to possible parasitic chemical reactions between the cathode and electrolyte at the much higher temperature (500 C) during discharge. The overall energy densities for these cathode were still less than for FeS{sub 2}.

  10. 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.

  11. 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.

  12. Experimental investigations on PVC-LiAsF 6-DBP polymer electrolyte systems

    NASA Astrophysics Data System (ADS)

    Rajendran, S.; Uma, T.

    Poly(vinyl chloride) (PVC)-LiAsF 6 polymer electrolytes plasticized with dibutyl phthalate in different mole ratios have been studied by means of X-ray diffraction (XRD), infrared spectroscopy (IR) and a.c. impedance spectroscopy. The complexation has been confirmed from XRD and IR studies. A maximum room temperature conductivity (3.938×10 -5 S cm -1) has been observed for PVC: LiAsF 6: DBP (10:5:85 mol%) complex. The log σ vs. 1/ T plots ( σ=electrical conductivity; T=temperature) show Arrhenius behaviour. The activation energy is estimated and the results are discussed.

  13. Growth and characterization of doped LiF crystals

    NASA Astrophysics Data System (ADS)

    Khan, Sajid; Kim, H. J.; Rooh, Gul; Kim, Sunghwan

    2014-12-01

    Transparent and crack-free crystals of LiF: x ( x = Ca, Pb, Na, Tl) were successfully grown by using the Czochralski method. Growth parameters such as the pulling and the rotation rates were optimized. The grown crystals were characterized and compared by using X-ray luminescence. Tl- and Na-doped crystals showed better luminescence intensity than crystals with other dopants. Thermoluminescence (TL) glow curves were obtained to study the crystal defects in the grown samples. Activation energies were calculated from the TL glow curves. The temperature dependence of the light yield in the temperature range from 10 to 300 K under alpha particle excitation was also investigated. The light yield was found to be larger at low temperatures. Na- and Tl-doped crystals showed 35% and 20% increases in the light yield, respectively, at low temperatures as compared to room temperature.

  14. Fabricating Hexagonal Al-Doped LiCoO2 Nanomeshes Based on Crystal-Mismatch Strategy for Ultrafast Lithium Storage.

    PubMed

    Xu, Hai-Tao; Zhang, Huijuan; Liu, Li; Feng, Yangyang; Wang, Yu

    2015-09-23

    In the designed synthesis, low crystal-mismatch strategy has been applied in the synthesis of ion-doped LiCoO2 materials, and a good success of single crystal property has been achieved between the precursor and the final sample for the first time. The hexagonal LiCo0.8Al0.26O2 (LCAO) nanomesh possesses several advantages in morphology and crystal structure, including mesoporous structure, single crystal, atomic even distribution, high exposing surface area as (100) or their equivalent planes, and shortened Li ions diffusion distance. All the merits are beneficial to the application in Li-ion batteries (LIBs) cathode, for example, accelerating Li ions diffusion rate, improving the Li ions shuttle between the LCAO nanomesh and electrolyte, and reducing the Li ions capacitive behavior during Li intercalation. Hence, our research adopts Al-contained precursor with morphology of hexagonal nanoplates to fabricate designed Al-doped LiCoO2 nanomeshes and greatly improves the cathode performance in LIBs. PMID:26333181

  15. First-principles study of LiPON and related solid electrolytes

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Lithium phosphorus oxynitride materials have been investigated for many years, especially in relation to the thin-film electrolyte LiPON, developed at Oak Ridge National Laboratory. We have carried out first-principles simulations of related crystalline materials as a first step toward understanding the sources of stability and mechanisms of Li-ion conductivity in these materials. In addition to a comprehensive survey of known crystalline materials related to LiPON, we have also predicted some materials. For example, starting with crystalline LiPO3 which has twisted phosphate chains, we considered the possibility of modifying the structure by substituting N and Li for O. The optimized structures were computed to have regularized phosphate chains which form planar -P-N-P-N- backbones. To the best of our knowledge, the predicted crystals, which we call s1-Li2PO2N with a 24-atom unit cell and s2-Li2PO2N with a 12-atom unit cell, have not yet been observed experimentally. We suggest several possible exothermic reaction pathways to synthesize these crystals.

  16. 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. PMID:26041380

  17. 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.

  18. Modern battery electrolytes: ion-ion interactions in Li+/Na+ conductors from DFT calculations.

    PubMed

    Jónsson, Erlendur; Johansson, Patrik

    2012-08-14

    Sodium-ion batteries, the sodium counterpart of the ubiquitous lithium-ion batteries, are currently being developed as a complementary technology to assure resource availability. As battery electrolytes tend to be one of the more limiting parts of any battery for both performance and life-length, chemical and physical data on sodium-ion battery electrolytes are important for rational development. Here the cation-anion interaction, a key property of any salt used in an electrolyte, of a number of salts is probed using numerous DFT methods via the ion-pair dissociation reaction: AlkAn ⇌ Alk(+) + An(-), where An(-) is any anion and Alk(+) is Na(+) or Li(+), the latter used here for a straight-forward literature and methodology comparison. Furthermore, the applicability of different DFT functionals for these types of calculations is benchmarked vs. a robust higher accuracy method (G4MP2). PMID:22751486

  19. 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.

  20. 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

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

    DOE PAGESBeta

    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 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

  2. 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.

  3. Effect of Li doping on the magnetic properties of ZnO nanomaterials

    NASA Astrophysics Data System (ADS)

    Rajamanickam, N.; Rajashabala, S.; Ramachandran, K.

    2013-06-01

    Zn1-xLixO (0 ≤ x ≥ 0.05) nanomaterials were synthesized by the solvothermal method and the influence of Li doping on the structural, optical, and magnetic properties was investigated. Morphological analysis by SEM revealed the formation of ZnO nanorods (NR) and Li-doped ZnO nanoparticles (NP), which indicate that doping of Li ions affects the morphology of ZnO. The magnetization curve of undoped ZnO indicates the co-existence of dia and antiferromagnetism, which changes to dia and ferrimagnetism with the addition of Li.

  4. 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.

  5. Geometry, electronic properties, and thermodynamics of pure and Al-doped Li clusters

    NASA Astrophysics Data System (ADS)

    Lee, Mal-Soon; Gowtham, S.; He, Haiying; Lau, Kah-Chun; Pan, Lin; Kanhere, D. G.

    2006-12-01

    The first-principles density functional molecular dynamics simulations have been carried out to investigate the geometric, the electronic, and the finite temperature properties of pure Li clusters ( Li10 , Li12 ) and Al-doped Li clusters ( Li10Al , Li10Al2 ). We find that the addition of two Al impurities in Li10 results in a substantial structural change, while the addition of one Al impurity causes a rearrangement of atoms. Introduction of Al impurities in Li10 establishes a polar bond between Li and nearby Al atom(s), leading to a multicentered bonding, which weakens the Li-Li metallic bonds in the system. These weakened Li-Li bonds lead to a premelting feature to occur at lower temperatures in Al-doped clusters. In Li10Al2 , Al atoms also form a weak covalent bond, resulting in their dimerlike behavior. This causes Al atoms not to “melt” until 800K , in contrast to the Li atoms which show a complete diffusive behavior above 400K . Thus, although one Al impurity in Li10 cluster does not change its melting characteristics significantly, two impurities results in “surface melting” of Li atoms whose motions are confined around an Al dimer.

  6. Barium Doped Li2FeSiO4 Cathode Material for Li-Ion Secondary Batteries.

    PubMed

    Kim, Cheong; Yoo, Gi Won; Son, Jong Tae

    2015-11-01

    Barium-doped Li2Fe(1-x)Ba(x)SiO4 (x = 0, 0.01) cathode materials were synthesized by the sol-gel and electrospinning processes. The structures of the samples were confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. The sizes and the morphologies of the particles and nanofibers were observed by field emission scanning electron microscopy and atomic force microscopy. The initial discharge capacity of Li2FeSiO4 particles was 28 mAh/g, Li2FeSiO4 nanofibers and barium (Ba)-doped Li2FeSiO4 nanofibers showed the discharge capacities of 78 and 85 mAh/g, respectively. The lithium-ion diffusion coefficients of Li2FeSiO4 particles, Li2FeSiO4 nanofibers and Ba-doped Li2FeSiO4 nanofibers were calculated 5.15 x 10-(16), 3.52 x 10(-16), and 2.27 x 10(-15) cm2/s, respectively. The Ba-doped Li2FeSiO4 cathode material showed the highest lithium-ion diffusion coefficient, and its electrochemical properties were better than that of the pristine material. PMID:26726598

  7. 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. PMID:27220376

  8. Mechanism of Photoinduced Charge Transfer in Co(Li)-Doped ZnO Film

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kenkichiro; Maeda, Tatsuro; Matsushima, Shigenori; Okada, Genji

    1992-08-01

    A three-layer film consisting of In-doped ZnO, Co(Li)-doped ZnO and Li-doped NiO has been fabricated by means of a sputtering technique. The photocurrent spectrum of the Co(Li)-doped ZnO has been measured by applying a bias voltage between the In-doped ZnO and Li-doped NiO electrodes. A broad peak around 640 nm in the photocurrent spectrum is assigned to photothermal ionization of Co2+ ions. The time dependence of photocurrents indicates that the concentration of Co2+ ions is decreased by the irradiation of 500 nm and is recovered to the initial value by turning off the bias voltage.

  9. 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

  10. Structural and Mechanistic Insights into Fast Lithium-Ion Conduction in Li4SiO4-Li3PO4 Solid Electrolytes.

    PubMed

    Deng, Yue; Eames, Christopher; Chotard, Jean-Noël; Lalère, Fabien; Seznec, Vincent; Emge, Steffen; Pecher, Oliver; Grey, Clare P; Masquelier, Christian; Islam, M Saiful

    2015-07-22

    Solid electrolytes that are chemically stable and have a high ionic conductivity would dramatically enhance the safety and operating lifespan of rechargeable lithium batteries. Here, we apply a multi-technique approach to the Li-ion conducting system (1-z)Li4SiO4-(z)Li3PO4 with the aim of developing a solid electrolyte with enhanced ionic conductivity. Previously unidentified superstructure and immiscibility features in high-purity samples are characterized by X-ray and neutron diffraction across a range of compositions (z = 0.0-1.0). Ionic conductivities from AC impedance measurements and large-scale molecular dynamics (MD) simulations are in good agreement, showing very low values in the parent phases (Li4SiO4 and Li3PO4) but orders of magnitude higher conductivities (10(-3) S/cm at 573 K) in the mixed compositions. The MD simulations reveal new mechanistic insights into the mixed Si/P compositions in which Li-ion conduction occurs through 3D pathways and a cooperative interstitial mechanism; such correlated motion is a key factor in promoting high ionic conductivity. Solid-state (6)Li, (7)Li, and (31)P NMR experiments reveal enhanced local Li-ion dynamics and atomic disorder in the solid solutions, which are correlated to the ionic diffusivity. These unique insights will be valuable in developing strategies to optimize the ionic conductivity in this system and to identify next-generation solid electrolytes. PMID:26118319

  11. Morphology and conductivity study of solid electrolyte Li3PO4

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    The comparison between two different methods of synthesize of solid electrolyte Li3PO4 as precursor material for developing lithium ion battery, has been performed. The first method is to synthesize Li3PO4 prepared by wet chemical reaction from LiOH and H3PO4 which provide facile, abundant available resource, low cost, and low toxicity. The second method is solid state reaction prepared by Li2CO3 and NH4H2PO4. 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 Li3PO4 powder products from two different reaction are characterized by SEM, EDS, and EIS. The Li3PO4 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 Li3PO4 prepared by wet chemical reaction is 2.238 gr/cm3, little bit lower than the sample prepared by solid state reaction which density is 2.3560 gr/cm3. The EIS measurement result shows that the conductivity of Li3PO4 is 1.7 x 10-9 S.cm-1 for wet chemical reaction and 1.8 x 10-10 S.cm-1 for solid state reaction. The conductivity of Li3PO4 is not quite different between those two samples even though they were prepared by different method of synthesize.

  12. Composite Gel Polymer Electrolyte Based on Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) with Modified Aluminum-Doped Lithium Lanthanum Titanate (A-LLTO) for High-Performance Lithium Rechargeable Batteries.

    PubMed

    Le, Hang T T; Ngo, Duc Tung; Kalubarme, Ramchandra S; Cao, Guozhong; Park, Choong-Nyeon; Park, Chan-Jin

    2016-08-17

    A composite gel polymer electrolyte (CGPE) based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) polymer that includes Al-doped Li0.33La0.56TiO3 (A-LLTO) particles covered with a modified SiO2 (m-SiO2) layer was fabricated through a simple solution-casting method followed by activation in a liquid electrolyte. The obtained CGPE possessed high ionic conductivity, a large electrochemical stability window, and interfacial stability-all superior to that of the pure gel polymer electrolyte (GPE). In addition, under a highly polarized condition, the CGPE effectively suppressed the growth of Li dendrites due to the improved hardness of the GPE by the addition of inorganic A-LLTO/m-SiO2 particles. Accordingly, the Li-ion polymer and Li-O2 cells employing the CGPE exhibited remarkably improved cyclability compared to cells without CGPE. In particular, the CGPE as a protection layer for the Li metal electrode in a Li-O2 cell was effective in blocking the contamination of the Li electrode by oxygen gas or impurities diffused from the cathode side while suppressing the Li dendrites. PMID:27463563

  13. Boron doped defective graphene as a potential anode material for Li-ion batteries.

    PubMed

    Hardikar, Rahul P; Das, Deya; Han, Sang Soo; Lee, Kwang-Ryeol; Singh, Abhishek K

    2014-08-21

    Graphene with large surface area and robust structure has been proposed as a high storage capacity anode material for Li ion batteries. While the inertness of pristine graphene leads to better Li kinetics, poor adsorption leads to Li clustering, significantly affecting the performance of the battery. Here, we show the role of defects and doping in achieving enhanced adsorption without compromising on the high diffusivity of Li. Using first principles density functional theory (DFT) calculations, we carry out a comprehensive study of diffusion kinetics of Li over the plane of the defective structures and calculate the change in the number of Li atoms in the vicinity of defects, with respect to pristine graphene. Our results show that the Li-C interaction, storage capacity and the energy barriers depend sensitively on the type of defects. The un-doped and boron doped mono-vacancy, doped di-vacancy up to two boron, one nitrogen doped di-vacancy, and Stone-Wales defects show low energy barriers that are comparable to pristine graphene. Furthermore, boron doping at mono-vacancy enhances the adsorption of Li. In particular, the two boron doped mono-vacancy graphene shows both a low energy barrier of 0.31 eV and better adsorption, and hence can be considered as a potential candidate for anode material. PMID:24986702

  14. Enhancing electrochemical intermediate solvation through electrolyte anion selection to increase nonaqueous Li-O2 battery capacity.

    PubMed

    Burke, Colin M; Pande, Vikram; Khetan, Abhishek; Viswanathan, Venkatasubramanian; McCloskey, Bryan D

    2015-07-28

    Among the "beyond Li-ion" battery chemistries, nonaqueous Li-O2 batteries have the highest theoretical specific energy and, as a result, have attracted significant research attention over the past decade. A critical scientific challenge facing nonaqueous Li-O2 batteries is the electronically insulating nature of the primary discharge product, lithium peroxide, which passivates the battery cathode as it is formed, leading to low ultimate cell capacities. Recently, strategies to enhance solubility to circumvent this issue have been reported, but rely upon electrolyte formulations that further decrease the overall electrochemical stability of the system, thereby deleteriously affecting battery rechargeability. In this study, we report that a significant enhancement (greater than fourfold) in Li-O2 cell capacity is possible by appropriately selecting the salt anion in the electrolyte solution. Using (7)Li NMR and modeling, we confirm that this improvement is a result of enhanced Li(+) stability in solution, which, in turn, induces solubility of the intermediate to Li2O2 formation. Using this strategy, the challenging task of identifying an electrolyte solvent that possesses the anticorrelated properties of high intermediate solubility and solvent stability is alleviated, potentially providing a pathway to develop an electrolyte that affords both high capacity and rechargeability. We believe the model and strategy presented here will be generally useful to enhance Coulombic efficiency in many electrochemical systems (e.g., Li-S batteries) where improving intermediate stability in solution could induce desired mechanisms of product formation. PMID:26170330

  15. 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.

  16. Irreversible morphological changes of a graphite negative-electrode at high potentials in LiPF6-based electrolyte solution.

    PubMed

    Domi, Yasuhiro; Doi, Takayuki; Tsubouchi, Shigetaka; Yamanaka, Toshiro; Abe, Takeshi; Ogumi, Zempachi

    2016-08-10

    The degradation mechanism of a graphite negative-electrode in LiPF6-based electrolyte solution was investigated using the basal plane of highly oriented pyrolytic graphite (HOPG) as a model electrode. Changes in the surface morphology were observed by in situ atomic force microscopy. In the initial cathodic scan, a number of pits appeared at around 1.75 V vs. Li(+)/Li, and fine particles formed on the terrace of the HOPG basal plane at about 1.5 V vs. Li(+)/Li. The fine particles were characterized by spectroscopic analysis, such as X-ray photoelectron spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy. We added one of the components to LiClO4-based electrolyte solution, and successfully reproduced the formation of pits and fine particles on the basal plane of HOPG. Based on these results, the formation mechanisms of pits and fine particle layers were proposed. PMID:27465798

  17. 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.

  18. Electrolyte Mixtures Based on Ethylene Carbonate and Dimethyl Sulfone for Li-Ion Batteries with Improved Safety Characteristics.

    PubMed

    Hofmann, Andreas; Migeot, Matthias; Thißen, Eva; Schulz, Michael; Heinzmann, Ralf; Indris, Sylvio; Bergfeldt, Thomas; Lei, Boxia; Ziebert, Carlos; Hanemann, Thomas

    2015-06-01

    In this study, novel electrolyte mixtures for Li-ion cells are presented with highly improved safety features. The electrolyte formulations are composed of ethylene carbonate/dimethyl sulfone (80:20 wt/wt) as the solvent mixture and LiBF4 , lithium bis(trifluoromethanesulfonyl)azanide, and lithium bis(oxalato)borate as the conducting salts. Initially, the electrolytes are characterized with regard to their physical properties, their lithium transport properties, and their electrochemical stability. The key advantages of the electrolytes are high flash points of >140 °C, which enhance significantly the intrinsic safety of Li-ion cells containing these electrolytes. This has been quantified by measurements in an accelerating rate calorimeter. By using the newly developed electrolytes, which are liquid down to T=-10 °C, it is possible to achieve C-rates of up to 1.5 C with >80 % of the initial specific capacity. During 100 cycles in cell tests (graphite||LiNi1/3 Co1/3 Mn1/3 O2 ), it is proven that the retention of the specific capacity is >98 % of the third discharge cycle with dependence on the conducting salt. The best electrolyte mixture yields a capacity retention of >96 % after 200 cycles in coin cells. PMID:25950145

  19. 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.

  20. 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. PMID:26178124

  1. 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.

  2. Separators for Li-ion and Li-metal battery including ionic liquid based electrolytes based on the TFSI- and FSI- anions.

    PubMed

    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

  3. 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

  4. 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.

  5. Fluorinated electrolyte for 4.5 V Li(Ni0.4Mn0.4Co0.2)O2/graphite Li-ion cells

    NASA Astrophysics Data System (ADS)

    Xia, Jian; Nie, M.; Burns, J. C.; Xiao, A.; Lamanna, W. M.; Dahn, J. R.

    2016-03-01

    A fluorinated electrolyte mixture, containing 1 M LiPF6/fluoroethylene carbonate:bis (2,2,2-trifluoroethyl) carbonate (1:1 w:w) with prop-1-ene-1,3-sultone as an electrolyte additive exhibited promising cycling and storage performance in Li(Ni0.4Mn0.4Co0.2)O2/graphite pouch type Li-ion cells tested to 4.5 V. The prop-1-ene-1,3-sultone additive was added to help control gas evolution in the fluorinated electrolyte cells, which was improved but still problematic even with the additive. Cells with the fluorinated electrolyte demonstrated higher impedance in early cycles compared to cells with carbonate solvents and state of the art additives. Symmetric cells were used to show this high impedance originated at the negative electrode/electrolyte interface. Nevertheless, in charge-discharge cycling tests to 4.5 V, cells with the fluorinated electrolyte and 1, 2 or 3% prop-1-ene-1,3-sultone additive, outperformed all non-fluorinated electrolytes with all additives tested. With further work, these, or other fluorinated carbonates, coupled with appropriate additives, may represent a viable path to NMC/graphite cells that can operate to 4.5 V and above.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Lithium-ion transfer at the interfaces between LiCoO2 and LiMn2O4 thin film electrodes and organic electrolytes

    NASA Astrophysics Data System (ADS)

    Yamada, Izumi; Miyazaki, Kohei; Fukutsuka, Tomokazu; Iriyama, Yasutoshi; Abe, Takeshi; Ogumi, Zempachi

    2015-10-01

    Interfacial reactions at positive electrodes and organic electrolytes interface for Li-ion batteries are studied by AC impedance methods. Thin film electrodes with flat and smooth surface are prepared by pulsed laser deposition, and the Li-ion transfer is investigated at structurally ordered interface. Charge transfer resistances attributed to Li-ion transfer at the interface are observed. The charge transfer resistances on LiMn2O4 thin film electrode are much smaller than those on c-axis orientated LiCoO2 thin film electrode, indicating that the charge transfer resistances are influenced by the number of active sites at the interface. Irrespective with positive electrode materials, activation energies evaluated from the temperature dependence of Li-ion transfer resistances are almost similar (about 50 kJ mol-1). These large activation energies suggest the existence of large energy barrier for Li-ion transfer at the interface between positive electrodes and organic electrolytes. After several charge-discharge cycles, some differences in the charge transfer resistances are observed; the increases in resistances on LiMn2O4 thin film electrode are smaller than those on LiCoO2 thin film electrode.

  11. 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.

  12. 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.

  13. Evaporation-Induced Self-Assembly of Nano-flaky Li3PS4 for Ultra thin Solid Electrolyte Membrane

    SciTech Connect

    Wang, Hui; Liang, Chengdu; Hood, Zachary; Hood, Zachary D; Xia, Younan

    2016-01-01

    Energy storage system is a critical technology to achieve efficient delivery and a steady supply of energy from intermittent sustainable sources (e.g. solar, wind). Lithium (Li) solid-state batteries are attractive candidates for next-generation batteries that require high energy density and stringent safety. In solid-state batteries, sulfides solid electrolytes are very promising to construct a large scale energy storage system. However, sulfide solid electrolyte pallets usually have an average thickness of 500-2000 m, which is 50 times that of the separators in conventional Li-ion batteries pose a huge challenge for their practical applications. Furthermore, the preparation of ultra-thin sulfide solid electrolyte membranes is difficult mainly due to the lack of efficient, low-cost solid electrolyte processing methods. Herein, we propose to use an evaporation-induced self-assembly (EISA) technique to produce ultra-thin sulfide solid electrolyte membranes. We designed and synthesized nano-flaky structured -Li3PS4 with high ionic conductivity, employed EISA method to produce ultra-thin -Li3PS4 membranes as thin as 8 m plus controllable thickness. It was clearly demonstrated that EISA method could be an facile approach to prepare solid electrolyte membranes.

  14. Optical properties of Li-doped ZnO films

    NASA Astrophysics Data System (ADS)

    Valentini, Antonio; Quaranta, Fabio; Vasanelli, Lorenzo; Piccolo, R.

    1991-03-01

    The difficulty to achieve a refractive index matching between active substrate and active layer grown on, is one of the main problem in integrated optical devices based on gallium arsenide, because of its high refractive index value. One possible solution could be an active layer whose refractive index is variable during the grown. Zinc oxide is a very interesting material because of its electro-optic and acousto- optic properties. It has a low cost and can be prepared by a variety of techniques. In this paper deposition of lithium doped zinc oxide films by reactive sputtering has been investigated in order to study the dependence of optical properties on lithium content and deposition parameters. A ZnO:Li target was used. The film depositions were performed varying the oxygen content in sputtering gas. For comparison undoped ZnO films were also prepared. We have performed optical and electrical measurement on films relating the results to Li contents and O/Zn ratio obtained by nuclear reaction and Rutherford backscattering measurements respectively. The film analysis has shown that dopant concentration is mainly controlled by gas mixture. The optical properties are dependent on deposition conditions. Optical waveguides have been prepared and characterized. The results are presented and discussed.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Reversible ion exchange and structural stability of garnet-type Nb-doped Li7La3Zr2O12 in water for applications in lithium batteries

    NASA Astrophysics Data System (ADS)

    Liu, Cai; Rui, Kun; Shen, Chen; Badding, Michael E.; Zhang, Gaoxiao; Wen, Zhaoyin

    2015-05-01

    H+/Li+ ion exchange and structural stability of the high ionic conductivity Nb-doped Zr-garnet Li6.75La3Nb0.25Zr1.75O12 (LLNZO) are investigated in this study. Relationships between ion exchange and Li-population per unit cell, which are necessary to establish the practical framework of garnet electrolytes, are deduced for garnet oxides within ion-exchange process. H+/Li+ ion exchange of cubic LLNZO powder is performed continuously in distilled water and products with various exchange levels are obtained via this simple method. FTIR spectra show the evolution of H-O bonding through the ion-exchange process. A maximum of 74.8% exchange of Li+ by H+ was found, consistent with a preferential replacement of octahedrally coordinated Li. The cubic garnet phase is maintained throughout all levels of proton exchange observed. The formation of garnet-type solid solution of Li6.75-xHxLa3Nb0.25Zr1.75O12 is indicated by well-resolved lattice fringes as well as the linear evolution of crystal lattice parameters with the ion exchange level. The reverse ion exchange of H+ by Li+ is successfully achieved in Li+ containing aqueous solutions, demonstrating its high structural stability and good compatibility for promising applications in lithium batteries.

  20. 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.

  1. B₂O₃-added lithium aluminium germanium phosphate solid electrolyte for Li-O₂ rechargeable batteries.

    PubMed

    Jadhav, Harsharaj S; Kalubarme, Ramchandra S; Jang, Seong-Yong; Jung, Kyu-Nam; Shin, Kyoung-Hee; Park, Chan-Jin

    2014-08-14

    B2O3-added Li(1.5)Al(0.5)Ge(1.5)(PO4)3 (LAGP) glass ceramics showing a room temperature ionic conductivity of 0.67 mS cm(-1) have been synthesized by using a melt-quenching method. The prepared glass ceramics are observed to be stable in tetraethylene glycol dimethyl ether containing lithium bis(trifluoromethane) sulfonamide. The augmented conductivity of the B2O3-added LAGP glass ceramic has improved the plateau potential during discharge. Furthermore, the B2O3-added LAGP glass ceramics are successfully employed as a solid electrolyte in a Li-O2 battery to obtain a stable cycling lifetime of up to 15 cycles with the limited capacity protocol. PMID:24953185

  2. Self-compensation property of β-rhombohedral boron doped with high Li concentration

    NASA Astrophysics Data System (ADS)

    Hyodo, H.; Nezu, A.; Soga, K.; Kimura, K.

    2012-11-01

    A high concentration of Li (up to LiB5.8; 18 Li/cell) was doped into β-rhombohedral boron (β-B), which has a crystalline structure built up from B12 icosahedral clusters, by sealing the raw materials in a stainless-steel tube. The relation between the structure and the electronic properties was clarified and a self-compensation property of Li- or Mg-doped β-B was discussed. The Li concentration was analyzed by atomic absorption spectrometry. The changes in the structure and the electronic properties were investigated by X-ray diffraction using the Rietveld method and by electrical conductivity measurements, respectively. Li occupies the A1, D, E and F sites, and the occupancies of the B sites (B13, B16 and B4) decrease with increasing Li doping. In Li- or Mg-doped β-B, electron doping is compensated by the removal of interstitial B atoms at the B16 site and by the generation of vacancies at the B13 and B4 sites. There have been no reports of self-compensation in other crystalline elemental semiconductors.

  3. Comb-branched Polymer Electrolytes: Architectural Changes That Promote Increased Li^+ Transport

    NASA Astrophysics Data System (ADS)

    Demille, Robert; Murthy, Sowmya; Bedrov, Dmitry; Smith, Grant

    2012-02-01

    The use of solid polymer electrolytes (SPEs) in the batteries of next generation technology applications is promising due to their safety and stability, yet is also hindered by low conductivity and high temperature requirements. Recent simulations of comb-branched poly(epoxide ether)-based SPEs have shown the comb-branched architecture to be able to overcome some of these hindrances. While providing the advantage of preventing crystallinity and allowing the optimization of the backbone to be decoupled from that of the side chain, the comb-branched SPE studied suffers from slow Li^+ cation dynamics due to coordination with the backbone. To improve Li^+ transport, we have modified the architecture of the comb-branched poly(epoxide ether) by attaching the side chains to the backbone with non-coordinating, flexible spacers. Inclusion of these spacers has resulted in a five-fold increase in the diffusion of Li^+ cation effected through 1) an increased side chain flexibility, 2) a decreased interaction of the cation with the dynamically slow backbone, and 3) quick conformational dynamics of the entire side chain. Additionally we report on other desirable architectural changes, such as including carbonate solvating moieties, to comb-branched SPEs allowing enhanced mobility of Li^+.

  4. Lithium difluoro(oxalate)borate and LiBF4 blend salts electrolyte for LiNi0.5Mn1.5O4 cathode material

    NASA Astrophysics Data System (ADS)

    Zhou, Hongming; Xiao, Kaiwen; Li, Jian

    2016-01-01

    The electrochemical behaviors of lithium difluoro(oxalate)borate (LiODFB) and LiBF4 blend salts in ethylene carbonate + dimethyl carbonate + ethyl(methyl) carbonate (EC + DMC + EMC, 1:1:1, by wt.) have been investigated for LiNi0.5Mn1.5O4 cathode in lithium-ion batteries. The electric conductivity tests are utilized to examine the relationship among solution conductivity, the electrolyte composition and temperature. Through cyclic voltammetry, charge-discharge test and AC impedance measurements, we compare the capacity and cycling efficiency of LNMO cathode in different electrolyte systems at different temperatures and discharge current rates. Scanning electron microscopy (SEM) analysis and X-ray photoelectron spectroscopy (XPS) are served to analyze the surface nature of LNMO cathode after cycles at elevated temperature. These results demonstrate that LNMO cathode can exert excellent electrochemical performance with the increase of LiODFB concentration at room temperature and elevated temperature and it is found that just slight LiBF4, mixed with LiODFB as blend salts, can strikingly improve the cyclability at -20 °C, especially in high-rate cycling. Grouped together, the optimum LiODFB/LiBF4 molar ratio is around 4:1, which can present an excellent affinity to LNMO cathode in a wide electrochemical window.

  5. Fabrication of p-type Li-doped ZnO films by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Xiao, Bin; Ye, Zhizhen; Zhang, Yinzhu; Zeng, Yujia; Zhu, Liping; Zhao, Binghui

    2006-11-01

    p-Type ZnO thin films have been realized via doping Li as acceptor by using pulsed laser deposition. In our experiment, Li 2CO 3 was used as Li precursor, and the growth temperature was varied from 400 to 600 °C in pure O 2 ambient. The Li-doped ZnO film prepared at 450 °C possessed the lowest resistivity of 34 Ω cm with a Hall mobility of 0.134 cm 2 V -1 s -1 and hole concentration of 1.37 × 10 18 cm -3. X-ray diffraction (XRD) measurements showed that the Li-doped ZnO films grown at different substrate temperatures were of completely (0 0 2)-preferred orientation.

  6. 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.

  7. 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.

  8. Optical and electrical properties of p-type Li-doped ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Sáaedi, Abdolhossein; Yousefi, Ramin; Jamali-Sheini, Farid; Cheraghizade, Mohsen; Khorsand Zak, A.; Huang, Nay Ming

    2013-09-01

    Undoped and Li-doped ZnO nanowires were grown on Si(1 1 1) substrates using a thermal evaporation method. Undoped and Li-doped ZnO nanoparticles, which were prepared using a sol-gel method, were used as material sources to grow the undoped and Li-doped ZnO nanowires, respectively. X-ray diffraction patterns clearly indicated hexagonal structures for all of the products. The nanowires were completely straight, with non-aligned arrays, and were tapered. Field emission Auger spectrometer indicated lithium element in the nanowires structures. Photoluminescence (PL) studies showed lower optical properties for the Li-doped ZnO nanowires compared to the undoped ZnO nanowires. Furthermore, the UV peak of the Li-doped ZnO nanowires was red-shifted compared to the undoped ZnO nanowires. Two probe method results proved that the Li-doped ZnO nanowires exhibited p-type properties.

  9. Magnetic properties of high Li doped ZnO sol–gel thin films

    SciTech Connect

    Vettumperumal, R.; Kalyanaraman, S.; Santoshkumar, B.; Thangavel, R.

    2014-02-01

    Highlights: • Ferromagnetism in high Li doped ZnO films. • Magnetic properties observed by Guoy's and VSM method. • The rod and wrinkle like structures are observed from the surface of the films. • Band gap of ZnO does not get altered by high Li doping. - Abstract: Undoped and Li doped ZnO thin films were deposited on a glass substrate using the sol–gel dip coating method. The films were prepared at 5 mol.% and 10 mol.% of Li doped ZnO at 550 °C annealing temperature and the deposited films were characterized by X-ray diffraction (XRD), microscopic studies, Gouy's method, vibrating sample magnetometer (VSM) and UV–visible spectroscopy. All the deposited thin films had a hexagonal wurtzite structure with polycrystalline grains at random. Primarily magnetic properties of pure and Li doped ZnO films were observed by Guoy's method which depicted Dia and Para magnetic behavior at room temperature. VSM measurement reveals a coercivity of 97.7 Oe in the films. An inverse relative ferromagnetism was perceived in Li doped ZnO films which had an average transmission of <90%.

  10. Investigation on the charging process of Li 2O 2-based air electrodes in Li-O 2 batteries with organic carbonate electrolytes

    NASA Astrophysics Data System (ADS)

    Xu, Wu; Viswanathan, Vilayanur V.; Wang, Deyu; Towne, Silas A.; Xiao, Jie; Nie, Zimin; Hu, Dehong; Zhang, Ji-Guang

    The charging process of Li 2O 2-based air electrodes in Li-O 2 batteries with organic carbonate electrolytes was investigated using in situ gas chromatography/mass spectroscopy (GC/MS) to analyze gas evolution. A mixture of Li 2O 2/Fe 3O 4/Super P carbon/polyvinylidene fluoride (PVDF) was used as the starting air electrode material, and 1-M lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) in carbonate-based solvents was used as the electrolyte. We found that Li 2O 2 was actively reactive to 1-methyl-2-pyrrolidinone and PVDF that were used to prepare the electrode. During the first charging (up to 4.6 V), O 2 was the main component in the gases released. The amount of O 2 measured by GC/MS was consistent with the amount of Li 2O 2 that decomposed during the electrochemical process as measured by the charge capacity, which is indicative of the good chargeability of Li 2O 2. However, after the cell was discharged to 2.0 V in an O 2 atmosphere and then recharged to ∼4.6 V, CO 2 was dominant in the released gases. Further analysis of the discharged air electrodes by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy indicated that lithium-containing carbonate species (lithium alkyl carbonates and/or Li 2CO 3) were the main discharge products. Therefore, compatible electrolytes and electrodes, as well as the electrode-preparation procedures, need to be developed for rechargeable Li-air batteries for long term operation.

  11. 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.

  12. 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.

  13. A High-Conduction Ge Substituted Li3AsS4 Solid Electrolyte with Exceptional Low Activation Energy

    SciTech Connect

    Sahu, Gayatri; Rangasamy, Ezhiylmurugan; Li, Juchuan; Chen, Yan; An, Ke; Dudney, Nancy J; Liang, Chengdu

    2014-01-01

    Lithium-ion conducting solid electrolytes show potential to enable high-energy-density secondary batteries and offer distinctive safety features as an advantage over traditional liquid electrolytes. Achieving the combination of high ionic conductivity, low activation energy, and outstanding electrochemical stability in crystalline solid electrolytes is a challenge for the synthesis of novel solid electrolytes. Herein we report an exceptionally low activation energy (Ea) and high room temperature superionic conductivity via facile aliovalent substitution of Li3AsS4 by Ge, which increased the conductivity by two orders of magnitude as compared to the parent compound. The composition Li3.334Ge0.334As0.666S4 has a high ionic conductivity of 1.12 mScm-1 at 27oC. Local Li+ hopping in this material is accompanied by distinctive low activation energy Ea of 0.17 eV being the lowest of Li+ solid conductors. Furthermore, this study demonstrates the efficacy of surface passivation of solid electrolyte to achieve compatibility with metallic lithium electrodes.

  14. Evaporation-Induced Self-Assembly of Nano-flaky Li3PS4 for Ultra thin Solid Electrolyte Membrane

    DOE PAGESBeta

    Wang, Hui; Liang, Chengdu; Hood, Zachary; Hood, Zachary D; Xia, Younan

    2016-01-01

    Energy storage system is a critical technology to achieve efficient delivery and a steady supply of energy from intermittent sustainable sources (e.g. solar, wind). Lithium (Li) solid-state batteries are attractive candidates for next-generation batteries that require high energy density and stringent safety. In solid-state batteries, sulfides solid electrolytes are very promising to construct a large scale energy storage system. However, sulfide solid electrolyte pallets usually have an average thickness of 500-2000 m, which is 50 times that of the separators in conventional Li-ion batteries pose a huge challenge for their practical applications. Furthermore, the preparation of ultra-thin sulfide solid electrolytemore » membranes is difficult mainly due to the lack of efficient, low-cost solid electrolyte processing methods. Herein, we propose to use an evaporation-induced self-assembly (EISA) technique to produce ultra-thin sulfide solid electrolyte membranes. We designed and synthesized nano-flaky structured -Li3PS4 with high ionic conductivity, employed EISA method to produce ultra-thin -Li3PS4 membranes as thin as 8 m plus controllable thickness. It was clearly demonstrated that EISA method could be an facile approach to prepare solid electrolyte membranes.« less

  15. 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.

  16. Spontaneous reaction between an uncharged lithium iron silicate cathode and a LiPF6-based electrolyte.

    PubMed

    Arthur, Zachary; Chiu, Hsien-Chieh; Lu, Xia; Chen, Ning; Emond, Vincent; Zaghib, Karim; Jiang, De-Tong; Demopoulos, George P

    2016-01-01

    The reaction between an uncharged Li2FeSiO4 (LFS) cathode and a LiPF6-EC/DMC electrolyte is revealed by in situ XANES in coin cells. This study shows clear evidence of delithiation and iron oxidation in LFS prior to cycling. Subsequent cycling appears to partially restore the original lithiation level, an observation that needs to be taken into consideration in future LFS development work. PMID:26511008

  17. Preparation and electrochromic properties of Li-doped MoO 3 films fabricated by the peroxo sol-gel process

    NASA Astrophysics Data System (ADS)

    Zhang, Yuzhi; Kuai, Sulan; Wang, Zhongchun; Hu, Xingfang

    2000-09-01

    Molybdenum oxide (MoO 3) films were prepared by the sol-gel process, using a lithium-doped peroxo-polymolybdate precursor solution. The highest quality films were obtained from precursor solutions containing 10% lithium. The structural properties of the films were characterized by TG-DTA and FTIR. The electrochemical and electrochromic properties were measured by cyclic voltammetry and an in-situ transmittance technique in 1 M LiClO 4/propylene carbonate electrolyte. The results show that the Li-doped MoO 3 films possess excellent electrochemical stability and reversibility, a remarkable change of transmittance (Δ T=32.3%) in visible region after coloration, and good electrochromic performance.

  18. Defects, stress and abnormal shift of the (0 0 2) diffraction peak for Li-doped ZnO films

    NASA Astrophysics Data System (ADS)

    Lin, Yow-Jon; Wang, Mu-Shan; Liu, Chia-Jyi; Huang, Hsueh-Jung

    2010-10-01

    The effect of changes in Li content on the structural property of sol-gel Li-doped ZnO films was investigated in this study. The observed changes of the Li incorporation-induced strain along c-axis are closely related to the different ratios between the concentrations of Li interstitials (Li i) and Li substituting for Zn (Li Zn) in the films. According to the observed results from X-ray diffraction (XRD) and photoluminescence measurements, we found that the domination of the dissociative mechanism in the Li-doped ZnO films led to transformation from Li Zn to Li i, involving the formation of Zn vacancies (V Zn). In addition, the interaction between these defects (that is, Li Zn, Li i, V Zn and oxygen vacancy) and the crystal structure may lead to the abnormal shift of the (0 0 2) diffraction peak position determined from XRD measurements.

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

    PubMed

    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. PMID:27111413

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

    PubMed

    Ma, Cheng; Rangasamy, Ezhiylmurugan; Liang, Chengdu; Sakamoto, Jeffrey; More, Karren L; Chi, Miaofang

    2015-01-01

    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 Li7 La3 Zr2 O12 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. These observations suggest that cubic Li7 La3 Zr2 O12 is a promising candidate for the separator in aqueous lithium batteries. PMID:25331968

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

    DOE PAGESBeta

    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 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

  2. 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.

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

    DOE PAGESBeta

    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 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

  4. Electrochemical properties of LiCoPO4-thin film electrodes in LiF-based electrolyte solution with anion receptors

    NASA Astrophysics Data System (ADS)

    Fukutsuka, Tomokazu; Nakagawa, Takuya; Miyazaki, Kohei; Abe, Takeshi

    2016-02-01

    Compatibility of LiF + anion receptors/propylene carbonate (PC) electrolyte solution with high potential positive electrode for lithium-ion batteries was examined by cyclic voltammetry. As anion receptors, tripropyl borate (TPB), tris(pentafluorophenyl) borane (TPFPB), and tris(hexafluoroisopropyl) borate (THFIPB) were used. LiCoPO4 thin-film electrodes were prepared by sol-gel method and used as both carbon- and binder-free model electrodes. From cyclic voltammograms, LiCoPO4 showed better cycleability in 0.1 mol dm-3 LiF + 0.1 mol dm-3 THFIPB/PC, however, other anion receptors did not give positive influence. It is indicated that the surface protecting layer from F--THFIPB complex and made LiCoPO4 stable. Electrochemical behavior depending on anion receptors was discussed according to reaction activity of F-.

  5. 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.

  6. Predicting autoxidation stability of ether- and amide-based electrolyte solvents for Li-air batteries.

    PubMed

    Bryantsev, Vyacheslav S; Faglioni, Francesco

    2012-07-01

    Finding suitable solvents remains one of the most elusive challenges in rechargeable, nonaqueous Li-air battery technology. Although ether and amides are identified as stable classes of aprotic solvents against nucleophilic attack by superoxide, many of them are prone to autoxidation under oxygen atmosphere. In this work, we use density functional theory calculations coupled with an implicit solvent model to investigate the autoxidative stability of ether- and N,N-dialkylamide-based solvents. The change in the activation free energy for the C-H bond cleavage by O(2) is consistent with the extent of peroxide production for each class of solvent. Conversely, the thermodynamic stability alone is not sufficient to account for the observed variation in solvent reactivity toward O(2). A detailed understanding of the factors influencing the autoxidative stability provides several strategies for designing molecules with enhanced air/O(2) stability, comparable or superior to that of structurally related hydrocarbons. The mechanism of superoxide-mediated oxidation of hydroperoxides derived from ethers and amides is presented. The degradation mechanism accounts for the primary decomposition products (esters and carboxylates) observed in the Li-air battery with ether-based electrolytes. The identification of solvents having resistance to autoxidation is critical for the development of rechargeable Li-air batteries with long cycle life. PMID:22681046

  7. Influence of Li-N and Li-F co-doping on defect-induced intrinsic ferromagnetic and photoluminescence properties of arrays of ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Ghosh, Shyamsundar; Gopal Khan, Gobinda; Varma, Shikha; Mandal, Kalyan

    2012-08-01

    The role of N/F co-doping on the defect-driven room-temperature d0 ferromagnetism in group-I element Li doped ZnO nanowire arrays has been investigated. The ferromagnetic signature of pristine ZnO nanowires has enhanced significantly after Li doping but the Li-N co-doping has found to be more effective in the stabilization and enhancement in room-temperature ferromagnetism in ZnO nanowires. Saturation magnetization in Li-doped ZnO nanowires found to increase from 0.63 to 2.52 emu/g and the Curie temperature rises up to 648 K when 10 at. % N is co-doped with 6 at. % Li. On the other hand, Li-F co-doping leads to exhibit much poor room-temperature ferromagnetic as well as visible luminescence properties. The valance state of the different dopants is estimated by x-ray photoelectron spectroscopy while the photoluminescence spectra indicate the gradual stabilization of Zn vacancy defects or defect complexes in presence of No acceptor states, which is found to be responsible for the enhancement of intrinsic ferromagnetism in ZnO:Li matrix. Therefore, the Li-N co-doping can be an effective parameter to stabilize, enhance, and tune zinc vacancy-induced room-temperature d0 ferromagnetism in ZnO nanowires, which can be an exciting approach to prepare new class of spintronic materials.

  8. Ferromagnetism in Dilute Magnetic Semiconductors through Defect Engineering: Li-Doped ZnO

    NASA Astrophysics Data System (ADS)

    Yi, J. B.; Lim, C. C.; Xing, G. Z.; Fan, H. M.; van, L. H.; Huang, S. L.; Yang, K. S.; Huang, X. L.; Qin, X. B.; Wang, B. Y.; Wu, T.; Wang, L.; Zhang, H. T.; Gao, X. Y.; Liu, T.; Wee, A. T. S.; Feng, Y. P.; Ding, J.

    2010-04-01

    We demonstrate, both theoretically and experimentally, that cation vacancy can be the origin of ferromagnetism in intrinsic dilute magnetic semiconductors. The vacancies can be controlled to tune the ferromagnetism. Using Li-doped ZnO as an example, we found that while Li itself is nonmagnetic, it generates holes in ZnO, and its presence reduces the formation energy of Zn vacancy, and thereby stabilizes the zinc vacancy. Room temperature ferromagnetism with p type conduction was observed in pulsed laser deposited ZnO:Li films with certain doping concentration and oxygen partial pressure.

  9. Ferromagnetism in dilute magnetic semiconductors through defect engineering: Li-doped ZnO.

    PubMed

    Yi, J B; Lim, C C; Xing, G Z; Fan, H M; Van, L H; Huang, S L; Yang, K S; Huang, X L; Qin, X B; Wang, B Y; Wu, T; Wang, L; Zhang, H T; Gao, X Y; Liu, T; Wee, A T S; Feng, Y P; Ding, J

    2010-04-01

    We demonstrate, both theoretically and experimentally, that cation vacancy can be the origin of ferromagnetism in intrinsic dilute magnetic semiconductors. The vacancies can be controlled to tune the ferromagnetism. Using Li-doped ZnO as an example, we found that while Li itself is nonmagnetic, it generates holes in ZnO, and its presence reduces the formation energy of Zn vacancy, and thereby stabilizes the zinc vacancy. Room temperature ferromagnetism with p type conduction was observed in pulsed laser deposited ZnO:Li films with certain doping concentration and oxygen partial pressure. PMID:20481907

  10. Control of point defects and grain boundaries in advanced materials. Optical properties and diffusion induced by Li doping in ZnO

    NASA Astrophysics Data System (ADS)

    Nakagawa, Tsubasa; Sakaguchi, Isao; Matsunaga, Katsuyuki; Yamamoto, Takahisa; Haneda, Hajime; Ikuhara, Yuichi

    2005-05-01

    Nickel diffusion in non-doped and Li-doped polycrystalline ZnO was studied to investigate the dominant lattice defect introduced by the reaction of incorporated Li. Li-doped ZnO exhibited new emission at 393 nm. Li doping increased the Ni lattice diffusion coefficients in ZnO, but its effect on Ni grain boundary diffusion was very small. These results can be understood as Li incorporation in the ZnO lattice.

  11. Investigation of Li-doped ferroelectric and piezoelectric ZnO films by electric force microscopy and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Ni, H. Q.; Lu, Y. F.; Liu, Z. Y.; Qiu, H.; Wang, W. J.; Ren, Z. M.; Chow, S. K.; Jie, Y. X.

    2001-08-01

    We have grown Li-doped ZnO films on silicon (100) using the rf planar magnetron sputtering method. The surface charges induced piezoelectrically by defect and by polarization can be observed by electric force microscopy. The Li-doped ZnO films have been proven to be ferroelectric. The Raman spectra of ZnO and Li-doped ZnO films have been measured.

  12. 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.

  13. Determining the 6Li doped side of a glass scintillator for ultra cold neutrons

    NASA Astrophysics Data System (ADS)

    Jamieson, Blair; Rebenitsch, Lori Ann

    2015-08-01

    Ultracold neutron (UCN) detectors using two visually very similar, to the microscopic level, pieces of optically contacted cerium doped lithium glasses have been proposed for high rate UCN experiments. The chief difference between the two glass scintillators is that one side is 6Li depleted and the other side 6Li doped. This note outlines a method to determine which side of the glass stack is doped with 6Li using AmBe and 252Cf neutron sources, and a Si surface barrier detector. The method sees an excess of events around the α and triton energies of neutron capture on 6Li when the enriched side is facing the Si surface barrier detector.

  14. Room-temperature ferromagnetism in Li-doped p -type luminescent ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Chawla, Santa; Jayanthi, K.; Kotnala, R. K.

    2009-03-01

    We have observed ferromagnetism in Li-doped ZnO nanorods with Curie temperature up to 554 K. Li forms shallow acceptor states in substitutional zinc sites giving rise to p -type conductivity. An explicit correlation emerges between increase in hole concentration with decrease in magnetization and Curie temperature in ZnO:Li. Occurrence of ferromagnetism at room temperature has been established with observed magnetic domain formation in ZnO:Li pellets in magnetic force microscopy and prominent ferromagnetic resonance signal in electron paramagnetic resonance spectrum. Magnetic ZnO:Li nanorods are luminescent, showing strong near UV emission. Substitutional Li atoms can induce local moments on neighboring oxygen atoms, which when considered in a correlated model for oxygen orbitals with random potentials introduced by dopant atom could explain the observed ferromagnetism and high Curie temperature in ZnO:Li nanorods.

  15. 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

  16. 3D hierarchical assembly of ultrathin MnO2 nanoflakes on silicon nanowires for high performance micro-supercapacitors in Li- doped ionic liquid

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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.

  17. Lithium related deep and shallow acceptors in Li-doped ZnO nanocrystals

    NASA Astrophysics Data System (ADS)

    Rauch, C.; Gehlhoff, W.; Wagner, M. R.; Malguth, E.; Callsen, G.; Kirste, R.; Salameh, B.; Hoffmann, A.; Polarz, S.; Aksu, Y.; Driess, M.

    2010-01-01

    We study the existence of Li-related shallow and deep acceptor levels in Li-doped ZnO nanocrystals using electron paramagnetic resonance (EPR) and photoluminescence (PL) spectroscopy. ZnO nanocrystals with adjustable Li concentrations between 0% and 12% have been prepared using organometallic precursors and show a significant lowering of the Fermi energy upon doping. The deep Li acceptor with an acceptor energy of 800 meV could be identified in both EPR and PL measurements and is responsible for the yellow luminescence at 2.2 eV. Additionally, a shallow acceptor state at 150 meV above the valence band maximum is made responsible for the observed donor-acceptor pair and free electron-acceptor transitions at 3.235 and 3.301 eV, possibly stemming from the formation of Li-related defect complexes acting as acceptors.

  18. Optical and surface properties of optically transparent Li3 PO4 solid electrolyte layer for transparent solid batteries.

    PubMed

    Pat, Suat; Özen, Soner; Şenay, Volkan; Korkmaz, Şadan

    2016-07-01

    In this study, optical and surface properties of the optically transparent Li3 PO4 solid electrolyte layer for transparent solid battery have been investigated for the first time. To determine the optical properties, transmittance, absorbance, reflection, refractive index spectra, and optical band gap were determined by UV-Vis spectrophotometer and optical interferometer. The surface property of the transparent Li3 PO4 solid electrolyte was analyzed using atomic force microscopy. One another important parameter is contact angle (CA) surface free energy (SFE). CA and SFE were determined by optical tensiometer. These values probably are a most important parameter for polymer and hybrid battery performance. For the best performance, value of CA should be low. As a result, solid electrolyte layer is a highly transparent and it has a high wettability. SCANNING 38:317-321, 2016. © 2015 Wiley Periodicals, Inc. PMID:26435203

  19. Stability of superoxide radicals in glyme solvents for non-aqueous Li-O2 battery electrolytes.

    PubMed

    Schwenke, K Uta; Meini, Stefano; Wu, Xiaohan; Gasteiger, Hubert A; Piana, Michele

    2013-07-28

    Glyme-based electrolytes were studied for the use in lithium-air batteries because of their greater stability towards oxygen reduction reaction intermediates (e.g., superoxide anion radicals (O2˙(-))) produced upon discharge at the cathode compared to previously employed carbonate-based electrolytes. However, contradictory results of glyme stability tests employing KO2 as an O2˙(-) source were reported in the literature. For clarification, we investigated the reaction of KO2 with glymes of various chain lengths qualitatively using (1)H NMR and FTIR spectroscopy as well as more quantitatively using UV-Vis spectroscopy. During our experiments we found a huge impact of small quantities of impurities on the stability of the solvents. Therefore, we studied further the influence of impurities in the glymes on the cycling behavior of Li-O2 cells, demonstrating the large effect of electrolyte impurities on Li-O2 cell performance. PMID:23760527

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

    PubMed

    Ramesh, S; Shanti, R; Morris, Ezra

    2013-01-01

    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. PMID:23044100

  1. Investigation on the Charging Process of Li2O2-Based Air Electrodes in Li-O2 Batteries with Organic Carbonate Electrolytes

    SciTech Connect

    Xu, Wu; Viswanathan, Vilayanur V.; Wang, Deyu; Towne, Silas A.; Xiao, Jie; Nie, Zimin; Hu, Dehong; Zhang, Jiguang

    2011-04-15

    The charge processes of Li-O2 batteries were investigated by analyzing the gas evolution by in situ gas chromatography-mass spectroscopy (GC/MS) technique. The mixture of Li2O2/Fe3O4/Super P carbon/polyvinylidene fluoride (PVDF) was used as the starting air electrode material and 1M LiTFSI in carbonate-based solvents was used as electrolyte. It was found that Li2O2 is reactive to 1-methyl-2-pyrrolidinone and PVDF binder used in the electrode preparation. During the 1st charge (up to 4.6 V), O2 was the main component in the gases released. The amount of O2 measured by GC/MS was consistent with the amount of Li2O2 decomposed in the electrochemical process as measured by the charge capacity, indicative of the good chargeability of Li2O2. However, after the cell was discharged to 2.0 V in O2 atmosphere and re-charged to ~ 4.6 V in the second cycle, CO2 was dominant in the released gases. Further analysis of the discharged air electrode by X-ray diffraction and Fourier transform infrared spectroscopy indicated that lithium-containing carbonate species (lithium alkyl carbonate and/or Li2CO3) were the main reaction products. Therefore, compatible electrolyte and electrodes as well as the electrode preparation procedures need to be developed for long term operation of rechargeable Li-O2 or Li-air batteries.

  2. Ab initio molecular dynamics simulations of organic electrolytes, electrodes, and lithium ion transport for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Kent, P. R. C.; Ganesh, P.; Jiang, De-En; Borodin, O.

    2012-02-01

    Optimizing the choice of electrolyte in lithium ion batteries and an understanding of the solid-electrolyte interphase (SEI) is required to optimize the balance between high-energy storage, high rate capability, and lifetime. We perform accurate ab initio molecular-dynamics simulations of common cyclic carbonates and LiPF6 to build solvation models which explain available Neutron and NMR spectroscopies. Our results corroborate why ethylene carbonate is a preferred choice for battery applications over propylene carbonate and how mixtures with dimethyl carbonate improve Li-ion diffusion. We study the role of functionalization of graphite-anode edges on the reducibility of the electrolyte and the ease of Li-ion intercalation at the initial stages of SEI formation. We find that oxygen terminated edges readily act as strong reductive sites, while hydrogen terminated edges are less reactive and allow faster Li diffusion. Orientational ordering of the solvent molecules precedes reduction at the interphase. Inorganic reductive components are seen to readily migrate to the anode edges, leading to increased surface passivation of the anode. We are currently quantifying Li-intercalation barriers across realistic SEI models, and progress along these lines will be presented.

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

    DOE PAGESBeta

    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 liquidmore » cell.« less

  4. 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.

  5. Kinetic stability of Li8 - 2 x M x ZrO6 ( M = Mg, Sr) and Li8 - x Zr1 - x V x O6 solid electrolytes in molten metallic lithium

    NASA Astrophysics Data System (ADS)

    Shchelkanova, M. S.; Pantyukhina, M. I.; Shevelin, P. Yu.; Suslov, E. A.

    2015-02-01

    The contact interaction of solid electrolytes based on Li8ZrO6 and Li8 - 2 x M x ZrO6 ( M = Mg, Sr) and Li8 - x Zr1 - x V x O6 solid solutions with molten metallic lithium is experimentally studied for the first time. The Li8 - 2 x M x ZrO6 ( M = Mg, Sr) and Li8 - x Zr1 - x V x O6 solid solutions are recommended for application as a solid electrolyte in high- and medium-temperature (573 K) lithium chemical current sources from the results of studying the kinetic stability to molten lithium.

  6. Mechanistic insights for the development of Li-O2 battery materials: addressing Li2O2 conductivity limitations and electrolyte and cathode instabilities.

    PubMed

    McCloskey, Bryan D; Burke, Colin M; Nichols, Jessica E; Renfrew, Sara E

    2015-08-18

    The Li-air battery has received significant attention over the past decade given its high theoretical specific energy compared to competing energy storage technologies. Yet, numerous scientific challenges remain unsolved in the pursuit of attaining a battery with modest Coulombic efficiency and high capacity. In this Feature Article, we provide our current perspective on challenges facing the development of nonaqueous Li-O2 battery cathodes. We initially present a review on our understanding of electrochemical processes occurring at the nonaqueous Li-O2 cathode. Electrolyte and cathode instabilities and Li2O2 conductivity limitations are then discussed, and suggestions for future materials research development to alleviate these issues are provided. PMID:26179598

  7. Multi-cations doped LiVPO4F cathode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Sun, Xiaofei; Xu, Youlong; Teng, Feng; Sun, Gongyu; Chen, Yanjun; Chen, Guogang

    2015-05-01

    The multi-cations doped LiVPO4F, nominally Li0.97Cr0.01V0.95Al0.01Nb0.02PO4F0.97, is prepared by Chromium (Cr) doping on lithium site and Al-Nb co-doping on vanadium site via a conventional carbothermal reduction (CTR) route. The crystallographic lattice volume, particle size and morphology are not obviously changed comparing with un-doped LiVPO4F. However, the high rate and lifetime cycling performances are noticeably improved although the capacities at very low currents are slightly decreased. The reversible capacity at 1/10 C, 1 C, 2 C and 4 C of the pristine LiVPO4F is 143 mA h g-1, 99 mA h g-1, 86 mA h g-1 and 70 mA h g-1, respectively, while that of the doped counterpart is 138 mA h g-1, 102 mA h g-1, 95 mA h g-1 and 82 mA h g-1, respectively. The capacity retention after 100 galvanostatic cycles at 1.5 C is enhanced from 85.4% to 90.9% by such multi-cations doping. Moreover, the initial coulombic efficiency is significantly increased from 81.8% to 90.3% as well.

  8. 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.

  9. 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.

  10. TL emission spectra from differently doped LiF:Mg detectors.

    PubMed

    Mandowska, E; Bilski, P; Ochab, E; Swiatek, J; Mandowski, A

    2002-01-01

    There are two widely applied types of thermoluminescent detectors based on LiF:Mg luminophor: Lif:Mg,Ti and highly sensitive LiF:Mg,Cu,P. The role of luminescence centres in these materials is usually attributed to defects connected with, respectively, titanium and phosphorus dopants. In order to check how composition of dopants introduced into the LiF lattice influences emission spectra, measurements on a series of variously doped LiF:Mg samples were performed. Apart from LiF:Mg,Cu,P and LiF:Mg,Ti detectors with different concentration of activators, an experimental sample being a kind of a 'hybrid' between both standard materials was also prepared. It was synthesised with concentrations of magnesium and copper identical to those used for LiF:Mg,Cu,P preparation. but instead of phosphorus it was doped with titanium (LiF:Mg,Cu,Ti). The measurements of the emission spectra were performed by using a liquid nitrogen cooled CCD 1024E detector with an SP150 spectrograph. During the measurements the samples were placed inside a cryostat in a vacuum. Resulting data were numerically deconvoluted for individual peaks with respect to the wavelength and the temperature. The glow curve shape of this material resembles that of LiF:Mg,Cu,P, while sensitivity is at the level of LiF:Mg,Ti. Preliminary results indicate that emission of the LiF:Mg,Cu,Ti sample is similar to that of LiF:Mg,Cu,P rather than to LiF:Mg,Ti, showing a maximum for wavelengths well below 400 nm. PMID:12382919

  11. 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. PMID:25125114

  12. Thermally and optically stimulated radiative processes in Eu and Y co-doped LiCaAlF6 crystal

    NASA Astrophysics Data System (ADS)

    Fukuda, Kentaro; Yanagida, Takayuki; Fujimoto, Yutaka

    2015-06-01

    Yttrium co-doping was attempted to enhance dosimeter performance of Eu doped LiCaAlF6 crystal. Eu doped and Eu, Y co-doped LiCaAlF6 were prepared by the micro-pulling-down technique, and their dosimeter characteristics such as optically stimulated luminescence (OSL) and thermally stimulated luminescence (TSL) were investigated. By yttrium co-doping, emission intensities of OSL and TSL were enhanced by some orders of magnitude. In contrast, scintillation characteristics of yttrium co-doped crystal such as intensity of prompt luminescence induced by X-ray and light yield under neutron irradiation were degraded.

  13. 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.

  14. 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. ...

  15. 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

  16. 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.

  17. Growth and optical properties of Mg, Fe Co-doped LiTaO3 crystal

    NASA Astrophysics Data System (ADS)

    Fang, Shuangquan; Ma, Decai; Zhang, Tao; Ling, Furi; Wang, Biao

    2006-02-01

    Mg, Fe double-doped LiTaO3 and LiNbO3 crystals have been grown by Czochralski method. The optical properties were measured by two-beam coupling experiments and transmitted facula distortion method. The results showed that the photorefractive response speed of Mg:Fe:LiTaO3 was about three times faster than that of Fe:LiTaO3, whereas the photo-damage resistance was two orders of magnitude higher than that of Fe:LiTaO3. In this paper, site occupation mechanism of impurities was also discussed to explain the high photo-damage resistance and fast response speed in Mg:Fe:LiTaO3 crystal.

  18. 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.

  19. Conductive surface modification of LiFePO4 with nitrogen doped carbon layers for lithium-ion batteries

    SciTech Connect

    Yoon, Sukeun; Liao, Chen; Sun, Xiao-Guang; Bridges, Craig A; Unocic, Raymond R; Nanda, Jagjit; Dai, Sheng; Paranthaman, Mariappan Parans

    2012-01-01

    The LiFePO4 rod surface modified with nitrogen doped carbon layer has been prepared using hydrothermal processing followed by post-annealing in the presence of an ionic liquid. The coated LiFePO4 rod exhibits good capacity retention and high rate capability as the nitrogen doped carbon improves conductivity and prevents aggregation of the rod during cycling.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  1. X-Ray absorption spectroscopy of LiBF4 in propylene carbonate: a model lithium ion battery electrolyte.

    PubMed

    Smith, Jacob W; Lam, Royce K; Sheardy, Alex T; Shih, Orion; Rizzuto, Anthony M; Borodin, Oleg; Harris, Stephen J; Prendergast, David; Saykally, Richard J

    2014-11-21

    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. PMID:25175723

  2. 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

  3. High performance C/S composite cathodes with conventional carbonate-based electrolytes in Li-S battery.

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

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

    DOE PAGESBeta

    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.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

  6. Performance Demonstration of Mcmb-LiNiCoO2 Cells Containing Electrolytes Designed for Wide Operating Temperature Range

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Whicanack, L. D.; Smith, K. A.; Santee, S.; Puglia, F. J.; Gitzendanner, R.

    2009-01-01

    With the intent of improving the performance of Li-ion cells over a wide operating temperature range, we have investigated the use of co-solvents to improve the properties of electrolyte formulations. In the current study, we have focused upon evaluating promising electrolytes which have been incorporated into large capacity (7 Ah) prototype Li-ion cells, fabricated by Yardney Technical Products, Inc. The electrolytes selected for performance evaluation include the use of a number of esters as co-solvents, including methyl propionate (MP), ethyl propionate (EP), ethyl butyrate (EB), propyl butyrate (PB), and 2,2,2-trifluoroethyl butyrate (TFEB). The performance of the prototype cells containing the ester-based electrolytes was compared with an extensive data base generated on cells containing previously developed all carbonate-based electrolytes. A number of performance tests were performed, including determining (i) the discharge rate capacity over a wide range of temperatures, (ii) the charge characteristics, (iii) the cycle life characteristics under various conditions, and (iv) the impedance characteristics.

  7. A comparison of the electrode/electrolyte reaction at elevated temperatures for various Li-ion battery cathodes

    NASA Astrophysics Data System (ADS)

    MacNeil, D. D.; Lu, Zhonghua; Chen, Zhaohui; Dahn, J. R.

    Differential scanning calorimetry (DSC) was used to compare the thermal stability of charged cathodes in 1 M LiPF 6 EC/DEC electrolyte. Seven possible cathode materials for lithium-ion batteries (LiCoO 2, LiNiO 2, LiNi 0.8Co 0.2O 2, Li 1+ xMn 2- xO 4, LiNi 0.7Co 0.2Ti 0.05Mg 0.05O 2, Li[Ni 3/8Co 1/4Mn 3/8]O 2, and LiFePO 4) were tested under the same conditions. Welded stainless steel DSC sample tubes, that ensured no weight loss during analysis, were used for these measurements, making them reliable. A consideration of these DSC results and the known electrochemical properties of the cathodes may assist the selection of the most suitable lithium-ion cathode material for use in a particular application.

  8. Growth and characterization of Li-doped ZnO thin films on nanocrystalline diamond substrates

    NASA Astrophysics Data System (ADS)

    Huang, Jian; Xia, Yiben; Wang, Linjun; Xu, Jinyong; Hu, Guang; Zhu, Xuefeng; Shi, Weimin

    2008-02-01

    Nanocrystalline diamond(NCD) films with a mean surface roughness of 23.8 nm were grown on silicon substrates in a hot filament chemical vapor deposition(HFCVD) system. Then, Zn 1-xLi xO (x=0, 0.05, 0.10, 0.15) films were deposited on these NCD films by radio-frequency(RF) reactive magnetron sputtering method. When x was 0.1, the Li-doped ZnO film had a larger resistivity more than 10 8Ω•cm obtained from Hall effect measurement. All the Zn 1-xLi xO films had a strong c-axis orientation structure determined by X-ray diffraction (XRD). The above results suggested that the Li-doped ZnO film/NCD structure prepared in this work was attractive for the application of high frequency surface acoustic wave (SAW) devices.

  9. Elastic properties of Li+ doped lead zinc borate glasses

    NASA Astrophysics Data System (ADS)

    Rajaramakrishna, R.; Lakshmikantha, R.; Anavekar, R. V.

    2014-04-01

    Glasses in the system 0.25PbO-(0.25-x) ZnO-0.5B2O3-xLi2O have been prepared by the melt quenching technique. Elastic properties, DSC studies have been employed to study the role of Li2O in the present glass system. Elastic properties and Debye temperature have been determined using pulsed echo ultrasonic interferometer operating at 10MHz. Sound velocities Vl, Vt and elastic moduli decrease up to 5 mol% and then gradually increase with increase in Li2O concentration. Debye temperature and the glass transition temperature decreases with increase in Li2O. Densities remains almost constant up to 15 mol% Li2O concentration and increases monotonically while the molar volume decreases with the increase of Li2O concentration. The results are discussed in view of the borate structural network and dual role of Zn and Pb in these glasses.

  10. Improved performance of Co-doped Li2O cathodes for lithium-peroxide batteries using LiCoO2 as a dopant source

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hiroaki; Hibino, Mitsuhiro; Ogasawara, Yoshiyuki; Yamaguchi, Kazuya; Kudo, Tetsuichi; Okuoka, Shin-ichi; Yonehara, Koji; Ono, Hironobu; Sumida, Yasutaka; Oshima, Masaharu; Mizuno, Noritaka

    2016-02-01

    We recently proposed a new battery system based on the redox of lithium peroxide (Li2O2)/lithium oxide (Li2O) at the cathode (lithium-peroxide battery system). In this system, the use of Li2O with cobalt ions partially substituted for lithium ions (Co-doped Li2O) is key to its realization. In this study, to further improve the cell performance, we prepare various Co-doped Li2O samples by a mechanochemical process using different cobalt source materials (e.g., LiCoO2, Co3O4, and CoO) and comparatively investigate them. Amongst the investigated cathode materials, the Co-doped Li2O sample prepared using LiCoO2 with a Co/(Co + Li) ratio of 0.09 exhibits the best performance. Monitoring of the pressure in the cell reveals that this Co-doped Li2O cathode can be charged to 270 mAh g-1 without O2 evolution involving its decomposition. Charge and discharge at 270 mAh g-1 is repeated more than 50 times. In addition, the rate-capability tests reveals that the redox reaction between peroxide and oxide ions is fast and that the cathode can be discharged at a high current density of 1000 mA g-1.

  11. Rechargeability of Li-air cathodes pre-filled with discharge products using an ether-based electrolyte solution: implications for cycle-life of Li-air cells.

    PubMed

    Meini, Stefano; Tsiouvaras, Nikolaos; Schwenke, K Uta; Piana, Michele; Beyer, Hans; Lange, Lukas; Gasteiger, Hubert A

    2013-07-21

    The instability of currently used electrolyte solutions and of the carbon support during charge-discharge in non-aqueous lithium-oxygen cells can lead to discharge products other than the desired Li2O2, such as Li2CO3, which is believed to reduce cycle-life. Similarly, discharge in an O2 atmosphere which contains H2O and CO2 impurities would lead to LiOH and Li2CO3 discharge products. In this work we therefore investigate the rechargeability of model cathodes pre-filled with four possible Li-air cell discharge products, namely Li2O2, Li2CO3, LiOH, and Li2O. Using Online Electrochemical Mass Spectrometry (OEMS), we determined the charge voltages and the gases evolved upon charge of pre-filled electrodes, thus determining the reversibility of the formation/electrooxidation reactions. We show that Li2O2 is the only reversible discharge product in ether-based electrolyte solutions, and that the formation of Li2CO3, LiOH, or Li2O is either irreversible and/or reacts with the electrolyte solution or the carbon during its oxidation. PMID:23748698

  12. Deposition of LiF onto Films of Fullerene Derivatives Leads to Bulk Doping.

    PubMed

    Torabi, Solmaz; Liu, Jian; Gordiichuk, Pavlo; Herrmann, Andreas; Qiu, Li; Jahani, Fatemeh; Hummelen, Jan C; Koster, L Jan Anton

    2016-08-31

    One of the most commonly used cathode interlayers for increasing the efficiency of electron injection/extraction in organic electronic devices is an ultrathin layer of LiF. Our capacitance measurements and electrical conductivity analysis show that thin films of fullerene derivatives and their mixtures with polymers are unintentionally doped upon deposition of LiF. The level of doping depends on the chemical structure of the fullerene derivatives. The doping effect on polymer/fullerene mixtures is significant only for blends in which the fullerene content is greater than the polymer content by weight. Our finding has profound implications for the development and characterization of organic photovoltaic devices, including a negative impact of doping on the stability of the device and erroneous estimations of properties such as charge carrier mobility and the dielectric constant. PMID:27526262

  13. Acoustic and Optical Properties of Er^3+- doped LiNbO3

    NASA Astrophysics Data System (ADS)

    Teklu, Alem; Kuthirummal, Narayanan; Morrall, Daniel; Dandrea, Jay

    2008-03-01

    Elastic constants of pure and Er^3+doped lithium niobate (LiNbO3) single crystals have been determined using resonant ultrasound spectroscopy (RUS). When comparing the elastic constants for pure and doped LiNbO3 crystals, the bulk modulus was found to increase by 5.2% after doping. Also the elastic constants were compared. C11 decreased by 4%, C12 increased by 18% and C44 increased by 16.6%. The surface-doping explains the decrease in elastic constant in only one direction. The presence of Er^3+ ions on the surface of LINbO3 has been monitored using photoacoustic spectroscopy. The photoacoustic spectrum revealed very weak absorptions corresponding to 4F^7/2, 4F^9/2 and 2H^11/2 levels of Erbium, indicating the presence of Erbium.

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

    DOE PAGESBeta

    Chen, Yan; Rangasamy, Ezhiylmurugan; dela Cruz, Clarina R.; Liang, Chengdu; An, Ke

    2015-09-28

    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

  15. Room-Temperature Magnetism Realized by Doping Fe into Ferroelectric LiTaO3

    NASA Astrophysics Data System (ADS)

    Song, Ying-Jie; Zhang, Qing-Hua; Shen, Xi; Ni, Xiao-Dong; Yao, Yuan; Yu, Ri-Cheng

    2014-01-01

    We synthesize LiTa1-xFexO3-σ (LTFO) ceramics by the conventional solid-state reaction method. The samples remain single phase up to x = 0.09. The magnetic measurements show that the doping of Fe successfully realizes ferromagnetism of LTFO at room temperature. The dielectric measurements indicate that LTFO is ferroelectric, similarly to LiTaO3 (LTO), but its ferroelectric Curie temperature seems to decrease with the increasing Fe content. By means of doping Fe ions into LTO, the coexistence of spontaneous electric polarization and spontaneous magnetic moment is realized at room temperature.

  16. Photoelectrochemical properties of highly mobilized Li-doped ZnO thin films.

    PubMed

    Shinde, S S; Bhosale, C H; Rajpure, K Y

    2013-03-01

    Li-doped ZnO thin films with preferred (002) orientation have been prepared by spray pyrolysis technique in aqueous medium on to the corning glass substrates. The effect of Li-doping on to the photoelectrochemical, structural, morphological, optical, luminescence, electrical and thermal properties has been investigated. XRD and Raman study indicates that the films have hexagonal crystal structure. The transmittance, reflectance, refractive index, extinction coefficient and bandgap have been analyzed by optical study. PL spectra consist of a near band edge and visible emission due to the electronic defects, which are related to deep level emissions, such as oxide antisite (OZn), interstitial zinc (Zni), interstitial oxygen (Oi) and zinc vacancy (VZn). The Li-doped ZnO films prepared for 1at% doping possesses the highest electron mobility of 102cm(2)/Vs and carrier concentration of 3.62×10(19)cm(-3). Finally, degradation of 2,4,6-Trinitrotoluene using Li-doped ZnO thin films has been reported. PMID:23416707

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

    DOE PAGESBeta

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

    NASA Astrophysics Data System (ADS)

    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.

  20. 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

    2016-01-01

    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

  1. 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.

  2. 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. PMID:27117633

  3. 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.

  4. Chemical stability and Ce doping of LiMgAlF6 neutron scintillator

    DOE PAGESBeta

    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.

  5. 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.

  6. Growth and photorefractive properties of Zn, Fe double-doped LiTaO 3 crystal

    NASA Astrophysics Data System (ADS)

    Fang, Shuangquan; Wang, Biao; Zhang, Tao; Ling, Furi; Wang, Rui

    2006-02-01

    Zn, Fe double-doped LiTaO3 crystals have been grown by the Czochralski method. The photorefractive properties and optical damage resistance were measured by the two-beam coupling experiments and transmitted facula distortion method, respectively. The results showed that the photorefractive response speed of Zn:Fe:LiTaO3 was about four times faster than that of Fe:LiTaO3, whereas the optical damage resistance was two orders of magnitude higher than that of Fe:LiTaO3. In this paper, site occupation mechanism of impurities was also discussed to explain the high optical damage resistance and fast response speed of Zn:Fe:LiTaO3 crystal.

  7. The effect of Li doping on the nonlinear optical properties of [2.2]paracyclophane.

    PubMed

    Sun, Gang; Duan, Xi-Xin; Liu, Chun-Guang

    2016-01-01

    The similar molecules [2.2]paracyclophane (22PCP) and 1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophane (8F22PCP) have both generated considerable synthetic interest since they were first prepared. In this work, the nonlinear optical properties of 22PCP, 8F22PCP, and the related Li-doped systems 22PCP-Li and 8F22PCP-Li (which have a Li atom above 22PCP and 8F22PCP, respectively) were investigated. An analysis of natural bond orbital charges showed that there is greater charge transfer from the Li atom to the benzene rings in 8F22PCP-Li than in 22PCP-Li. The variation in the calculated nucleus independent chemical shift (NICS) value as a function of the distance from the lower benzene ring towards the upper benzene ring was found to be W-shaped for both 22PCP and 22PCP-Li. Moreover, whereas all of the NICS values of 22PCP and 22PCP-Li were markedly negative, all of the NICS values of 8F22PCP and 8F22PCP-Li were either positive or only moderately negative. Calculations of the electro-optical properties of these systems showed that the first hyperpolarizability of 22PCP-Li was noticeably larger than that of 8F22PCP-Li. According to the two-level model, the larger first hyperpolarizability of 22PCP-Li is due to its smaller transition energy. PMID:26733484

  8. Direct measurement of the chemical reactivity of silicon electrodes with LiPF6-based battery electrolytes.

    PubMed

    Veith, Gabriel M; Baggetto, Loïc; Sacci, Robert L; Unocic, Raymond R; Tenhaeff, Wyatt E; Browning, James F

    2014-03-21

    We report the first direct measurement of the extent of the spontaneous non-electrochemically driven reaction between a lithium ion battery electrode surface (Si) and a liquid electrolyte (1.2 M LiPF6-3 : 7 wt% ethylene carbonate : dimethyl carbonate). This layer is estimated to be 35 Å thick with a SLD of ∼ 4 × 10(-6) Å(-2) and likely originates from the consumption of the silicon surface. PMID:24513965

  9. 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.

  10. 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.

  11. Preparation and characterization of poly(vinyl chloride-co-vinyl acetate)-based gel electrolytes for Li-ion batteries

    SciTech Connect

    Sung, H.Y.; Wang, Y.Y.; Wan, C.C.

    1998-04-01

    Poly(vinyl chloride) (PVC)-based electrolytes, a class of the most promising polymer electrolytes, are found to suffer from solvent exudation. Two strategies were employed to suppress this shortcoming, one involving the replacement of PVC with poly(vinyl chloride-co-vinyl acetate) (PVCAC) copolymer and the other the direct utilization of solvents for PVC or PVCAC instead of using an auxiliary carrier solvent (e.g., tetrahydrofuran, THF). The thermodynamics of polymer solubility was particularly emphasized in the latter approach. N,N-dimethylformamide (DMF) and N-methyl pyrrolidionone (NMP) are preferred cosolvents of ethylene carbonate (EC) and/or propylene carbonate (PC). The PVCAC-based gel electrolytes prepared were then characterized by ionic conductivity, cyclic voltammetry, and ac impedance data. The results indicate that electrolytes containing NMP/EC mixed solvent exhibit conductivities exceeding 10{sup {minus}3} S/cm whereas the electrolytes containing DMF/EC/PC exhibit conductivities around 10{sup {minus}4} S/cm at room temperature. Moreover, the former category was found to be oxidatively stable up to 4.9 V vs. Li/Li{sup +} and the latter to 4.6 V vs. Li/Li{sup +}. Finally, ac impedance results suggest that the stability of the Li/electrolyte interface needs further improvement, which is a crucial task for most polymer gel electrolytes at present.

  12. Electrical Conductivity Study of Polymer Electrolyte Magnetic Nanocomposite Based Poly(Vinyl) Alcohol (PVA) Doping Lithium and Nickel Salt

    NASA Astrophysics Data System (ADS)

    Aji, Mahardika Prasetya; Rahmawati, Silvia, Bijaksana, Satria; Khairurrijal, Abdullah, Mikrajuddin

    2010-10-01

    Composite polymer electrolyte magnetic systems composed of poly(vinyl) alcohol (PVA) as the host polymer, lithium and nickel salt as dopant were studied. The effect upon addition of lithium ions in polimer PVA had been enhanced conductivity with the increase of lithium concentration. The conductivity values were 1.19x10-6, 1.25x10-5, 4.89x-5, 1.88x10-4, and 1.33x10-3 Sṡcm-1 for pure PVA and 1%, 3%, 5% and 7% LiOH complexed PVA, respectively. Meanwhile, the addition nickel salt into polymer electrolyte PVA-LiOH does not significantly change of conductivity value, on order 10-3 Sṡcm-1. The ionic transport is dominantly regarded by Li+ ions present in polymer electrolyte magnetic because the atomic mass Li+ is smaller than Ni2+. The absence of external magnetic field in polimer electrolyte magnetic causes the existence Ni2+ ions not significantly affected of conductivity.

  13. 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

    2016-01-01

    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

  14. 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

  15. Nickel supported on nitrogen-doped carbon nanotubes as hydrogen oxidation reaction catalyst in alkaline electrolyte

    DOE PAGESBeta

    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 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

  16. Nickel supported on nitrogen-doped carbon nanotubes as hydrogen oxidation reaction catalyst in alkaline electrolyte

    NASA Astrophysics Data System (ADS)

    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.

  17. 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. PMID:27282172

  18. 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. PMID:27561892

  19. Growth and nonlinear optical properties of Zn-doped LiB3O5 crystals

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Yue, Yinchao; Mao, Qian; Li, Xiaomao; Hu, Zhanggui

    2015-05-01

    Zn-doped LiB3O5 (LBO) single crystals with high quality were successfully grown from the Li2O-MoO3-ZnF2 ternary system by the top-seeded solution growth method. The suitable region for LBO crystal growth was investigated by growth experiments, as well as viscosity and volatility measurements, which confirmed that the optimal molar ratio of Li2O:MoO3:ZnF2 was 1:1.5:0.2. The second-harmonic generation efficiency of Zn-doped LBO crystal increased by 16% compared with that of the LBO crystals grown from the MoO3 flux. The optical homogeneity was at 10-6 cm-1. Optical absorption at the critical wavelengths of 1064 nm was measured to be 15 and 18 ppm cm-1, respectively.

  20. 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.

  1. Interface-enhanced Li ion conduction in a LiBH4-SiO2 solid electrolyte.

    PubMed

    Choi, Yong Seok; Lee, Young-Su; Oh, Kyu Hwan; Cho, Young Whan

    2016-08-10

    We have developed a fast solid state Li ion conductor composed of LiBH4 and SiO2 by means of interface engineering. A composite of LiBH4-SiO2 was simply synthesized by high energy ball-milling, and two types of SiO2 (MCM-41 and fumed silica) having different specific surface areas were used to evaluate the effect of the LiBH4/SiO2 interface on the ionic conductivity enhancement. The ionic conductivity of the ball-milled LiBH4-MCM-41 and LiBH4-fumed silica mixture is as high as 10(-5) S cm(-1) and 10(-4) S cm(-1) at room temperature, respectively. In particular, the conductivity of the latter is comparable to the LiBH4 melt-infiltrated into MCM-41. The conductivities of the LiBH4-fumed silica mixtures at different mixing ratios were analyzed employing a continuum percolation model, and the conductivity of the LiBH4/SiO2 interface layer is estimated to be 10(5) times higher than that of pure bulk LiBH4. The result highlights the importance of the interface and indicates that significant enhancement in ionic conductivity can be achieved via interface engineering. PMID:27468702

  2. 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.

  3. Enhancement of hydrogen physisorption on graphene and carbon nanotubes by Li doping.

    PubMed

    Cabria, I; López, M J; Alonso, J A

    2005-11-22

    Density-functional calculations of the adsorption of molecular hydrogen on a planar graphene layer and on the external surface of a (4,4) carbon nanotube, undoped and doped with lithium, have been carried out. Hydrogen molecules are physisorbed on pure graphene and on the nanotube with binding energies about 80-90 meV/molecule. However, the binding energies increase to 160-180 meV/molecule for many adsorption configurations of the molecule near a Li atom in the doped systems. A charge-density analysis shows that the origin of the increase in binding energy is the electronic charge transfer from the Li atom to graphene and the nanotube. The results support and explain qualitatively the enhancement of the hydrogen storage capacity observed in some experiments of hydrogen adsorption on carbon nanotubes doped with alkali atoms. PMID:16351307

  4. Kinetic investigation of catalytic disproportionation of superoxide ions in the non-aqueous electrolyte used in Li-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Zheng, Dong; McKinnon, Meaghan E.; Yang, Xiao-Qing; Qu, Deyang

    2015-01-01

    Superoxide reacts with carbonate solvents in Li-air batteries. Tris(pentafluorophenyl)borane is found to catalyze a more rapid superoxide (O2-) disproportionation reaction than the reaction between superoxide and propylene carbonate (PC). With this catalysis, the negative impact of the reaction between the electrolyte and O2- produced by the O2 reduction can be minimized. A simple kinetic study using ESR spectroscopy was reported to determine reaction orders and rate constants for the reaction between PC and superoxide, and the disproportionation of superoxide catalyzed by Tris(pentafluorophenyl)borane and Li ions. The reactions are found to be first order and the rate constants are 0.033 s-1 M-1, 0.020 s-1 M-1 and 0.67 s-1 M-1 for reactions with PC, Li ion and Tris(pentafluorophenyl)borane, respectively.

  5. Effects of O vacancies and N or Si substitutions on Li+ migration in Li3PO4 electrolytes from first principles

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

    As a first step toward optimizing solid-state electrolyte materials, we have constructed realistic models of various types of isolated defects in crystalline Li3PO4 involving O vacancies and N and Si dopants, and have used first-principles calculational methods to study their effects on the production and migration of mobile Li ions. We find that mobile Li-ion vacancies are stabilized by removing oxygen from the lattice, which, in turn, causes the rebonding of nearby phosphate groups to form O3P-O-PO3 (POP) structures embedded in the crystal. In the presence of nitrogen in the system, the POP structures can be further stabilized by replacing the bridging oxygen with nitrogen. We examine the electronic and geometric structures of these stable POP and O3P-N-PO3 (PNP) defects which are prototypes of chain structures found in thin-film lithium phosphorus oxynitride (LiPON) electrolytes. We also find that mobile interstitial Li ions are stabilized by N or Si dopants substituting for O or P host ions and forming PO3N or SiO4 defects, respectively. In all of these cases, the defect not only stabilizes extrinsic mobile ions but also provides traps for the ions to escape into the bulk regions of the crystal by as much as 1.5 eV for the vacancies and 0.9 eV for the interstitials. On the other hand, migration barriers for diffusion steps near the defects are as small as 0.4-0.6 eV for the vacancies and 0.2-0.3 eV for the interstitials. Extrapolating our results to crystals with appreciable concentrations of defects, we find that our results compare favorably with experimental migration energies reported in the literature.

  6. Probing the Degradation Mechanisms in Electrolyte Solutions for Li-ion Batteries by In-Situ Transmission Electron Microscopy

    SciTech Connect

    Abellan Baeza, Patricia; Mehdi, Beata L.; Parent, Lucas R.; Gu, Meng; Park, Chiwoo; Xu, Wu; Zhang, Yaohui; Arslan, Ilke; Zhang, Jiguang; Wang, Chong M.; Evans, James E.; Browning, Nigel D.

    2014-02-21

    One of the goals in the development of new battery technologies is to find new electrolytes with increased electrochemical stability. In-situ (scanning) transmission electron microscopy ((S)TEM) using an electrochemical fluid cell provides the ability to rapidly and directly characterize electrode/electrolyte interfacial reactions under battery relevant electrochemical conditions. Furthermore, as the electron beam itself causes a localized electrochemical reaction when it interacts with the electrolyte, the breakdown products that occur during the first stages of battery operation can potentially be simulated and characterized using a straightforward in-situ liquid stage (without electrochemical biasing capabilities). In this paper, we have studied the breakdown of a range of inorganic/salt complexes that are used in state-of-the-art Li-ion battery systems. 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 can be used to directly test new electrolyte designs and provide structural insights into the origin of the solid electrolyte interphase (SEI) formation mechanism.

  7. Role of Ce and In doping in the performance of LiFePO4 cathode material for Li ion Batteries

    NASA Astrophysics Data System (ADS)

    Mandal, Balaji; Nazri, Mariam; Vaishnava, Prem P.; Naik, Vaman M.; Nazri, Gholam A.; Naik, Ratna

    2012-02-01

    Recently, the olivine LiFePO4 has attracted attention as a promising cathode material for Li ion batteries. However, its poor electronic conductivity is a major challenge for its industrial applications. Different approaches have been taken to address this problem. Here, we report a method of improving its conductivity by doping In and Ce ions at the Fe site. We prepared the samples by sol-gel method followed by annealing at 650 C in Ar (95%) +H2(5%) atmosphere for 5 hrs. XRD and Raman spectroscopy confirm that the olivine structure remains unchanged upon doping with In and Ce up to 5 wt%. XRD analysis shows the values of the lattice parameters increase with doping as the ionic radii of Ce and In ions are larger than that of the Fe^2+ ion. This observation also suggests that both Ce and In ions replace Fe ions and not the Li ions in the material. Upon doping, ionic conductivity was found to increase from 10-9 to 10-4 Ohm-1cm-1. Interestingly, Ce doped LiFePO4 showed a higher conductivity than In doped LiFePO4. SEM measurements show a bigger grain size of ˜300-500 nm in doped LiFePO4 which decreased to ˜50 nm when the materials were synthesized using 0.25M lauric acid as a precursor. The electrochemical characteristics of the doped LiFePO4 along with conductivity and Raman data will be presented.

  8. 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.

  9. Electrochemical investigation of the role of MnO2 nanorod catalysts in water containing and anhydrous electrolytes for Li-O2 battery applications.

    PubMed

    Geaney, Hugh; O'Dwyer, Colm

    2015-03-14

    The electrochemical behaviour of MnO2 nanorod and Super P carbon based Li-O2 battery cathodes in water-containing sulfolane and anhydrous DMSO electrolytes are shown to be linked to specific discharge product formation. During discharge, large layered spherical agglomerates of LiOH were characteristically formed on the MnO2 cathodes while smaller, toroidal, spherical Li2O2 particles and films were formed on the Super P cathodes. In an anhydrous DMSO based electrolyte the LiOH structures were also found on cathodes discharged in the anhydrous electrolyte, suggesting that MnO2 initiates electrochemical decomposition of the DMSO electrolyte to form LiOH via H2O reactions with Li2O2. The LiOH crystals are uniquely formed on MnO2, and segregated to this phase even in mixed oxide-carbon cathodes. In contrast, no Li2O2 toroids were noted on Super P cathodes discharged in the DMSO based electrolytes. Instead, the morphology varied from smaller sheets (at high discharge current) to much larger agglomerates (at low discharge currents). In mixed carbon-MnO2 nanorod cathodes, the use of PVDF initiates H2O formation that affects discharge products and an overall mechanism governing phase formation at MnO2 in sulfolane and anhydrous DMSO with and without PVDF binder is presented. This work highlights the importance of careful consideration of electrolyte-cathode material-discharge product interactions in the search for more stable Li-O2 systems. PMID:25640321

  10. Electrical transport properties of ReS2 with polymer electrolyte gating in the high-doping limit

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, Dmitry; Allain, Adrien; Pasquier, Diego; Dumcenco, Dumitru; Ho, Ching-Hwa; Huang, Ying-Sheng; Yazyev, Oleg; Kis, Andras

    Two-dimensional (2D) materials have emerged as promising candidates for future electronic applications. Among them, transition metal dichalcogenides (TMDs) demonstrate not only potential as ultrathin transistor channel material, but also intriguing spin and valley physics, which in principle could allow new types of devices and circuits. Here we report on the first study of two-dimensional anisotropic ReS2 at high doping levels, enabled by polymer electrolyte gating. Significantly increasing the doping level using electrolyte instead of standard solid gate, we measured an unusual modulation of the conductivity at high carrier densities in monolayer ReS2. In the case of thicker flakes, the effect is milder and an insulator-metal-insulator sequence with increasing doping is observed. Transport measurements provide the evidence of major influence of ionic disorder. Furthermore, we discuss possible band structure effects.

  11. Structural transition in Mg-doped LiMn 2O 4: a comparison with other M-doped Li-Mn spinels

    NASA Astrophysics Data System (ADS)

    Capsoni, Doretta; Bini, Marcella; Chiodelli, Gaetano; Massarotti, Vincenzo; Mozzati, Maria Cristina; Azzoni, Carlo B.

    2003-01-01

    The charge distribution in the Mg-doped lithium manganese spinel Li 1.02Mg xMn 1.98- xO 4 with 0.00< x≤0.20 is discussed and compared to those pertinent to other M-doped samples (M=Ni 2+, Co 3+, Cr 3+, Al 3+ and Ga 3+). EPR spectra, low temperature X-ray diffraction and conductivity data are related to the cooperative Jahn-Teller (J-T) transition occurring at about 280 K in the undoped sample. The sensitivity of the cationic sublattice in displaying electronic and magnetic changes after substitution is remarked. The inhibition of the J-T transition is related to the ratio r=|Mn 4+|/|Mn 3+| as deduced from the charge distribution model [Li 1- xt+Mg xt2+] tetr[Li y+ xt+Mg xo2+Mn 1-3 y-2 x3+Mn 1+2 y+ x4+] octa where x= xo+ xt. For y=0.02 and x=0.02, a value r=1.177 is obtained, very close to rlim=1.18, the limit value beyond which the transition is inhibited.

  12. Dynamic in situ fourier transform infrared measurements of chemical bonds of electrolyte solvents during the initial charging process in a Li ion battery

    NASA Astrophysics Data System (ADS)

    Hongyou, Kenichi; Hattori, Takashi; Nagai, Youko; Tanaka, Toshihiro; Nii, Hiroyuki; Shoda, Kaoru

    2013-12-01

    Solvation/desolvation and the solid electrolyte interphase (SEI) formation at a graphite electrode during the initial charging process were investigated using in situ Fourier transform infrared spectroscopy (FTIR) measurements. These measurements were developed by applying a diamond attenuated total reflectance (ATR) crystal, which probed the electrolyte solvents at the surface of the graphite electrode and provided successive FTIR spectra with high signal-to-noise ratio. The charging process was performed in the Li(reference)/electrolyte/graphite(working)/Cu cell at a voltage ranging from 3.2 to 0.0001 V vs. Li/Li+. The measurement elucidated the change in the chemical bond of the electrolyte solvents. In an early stage, the amounts of solvated and desolvated solvents changed, providing evidence that the Li+ ions were intercalated into the graphite layer. The formation of the Li alkyl carbonate that forms the SEI layer was facilitated toward the end of the charging process. Measurements were also obtained of the electrolyte with a vinylene carbonate additive, and the contribution of the additive to the electrolyte solvent reduction was investigated.

  13. 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

    2015-12-01

    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. PMID:26524078

  14. Identification of acceptor states in Li-doped p-type ZnO thin films

    NASA Astrophysics Data System (ADS)

    Zeng, Y. J.; Ye, Z. Z.; Lu, J. G.; Xu, W. Z.; Zhu, L. P.; Zhao, B. H.; Limpijumnong, Sukit

    2006-07-01

    We investigate photoluminescence from reproducible Li-doped p-type ZnO thin films prepared by dc reactive magnetron sputtering. The LiZn acceptor state, with an energy level located at 150meV above the valence band maximum, is identified from free-to-neutral-acceptor transitions. Another deeper acceptor state located at 250meV emerges with the increased Li concentration. A broad emission centered at 2.96eV is attributed to a donor-acceptor pair recombination involving zinc vacancy. In addition, two chemical bonding states of Li, evident in x-ray photoelectron spectroscopy, are probably associated with the two acceptor states observed.

  15. Toward 5 V Li-Ion Batteries: Quantum Chemical Calculation and Electrochemical Characterization of Sulfone-Based High-Voltage Electrolytes.

    PubMed

    Wu, Feng; Zhou, Hang; Bai, Ying; Wang, Huali; Wu, Chuan

    2015-07-15

    In seeking new sulfone-based electrolytes to meet the demand of 5 V lithium-ion batteries, we have combined the theoretical quantum chemistry calculation and electrochemical characterization to explore several sulfone/cosolvent systems. Tetramethylene sulfone (TMS), dimethyl sulfite (DMS), and diethyl sulfite (DES) were used as solvents, and three kinds of lithium salts including LiBOB, LiTFSI, and LiPF6 were added into TMS/DMS [1:1, (v)] and TMS/DES [1:1, (v)] to form high-voltage electrolyte composites, respectively. All of these electrolytes display wide electrochemical windows of more than 5.4 V, with the high electrolyte conductivities being more than 3 mS/cm at room temperature. It is indicated that to achieve the best ionic conductivity in TMS/DMS cosolvent, the optimized concentrations of lithium salts LiBOB, LiTFSI, and LiPF6 were 0.8, 1, and 1 M, respectively. Furthermore, the vibrational changes of the molecular functional groups in the cosolvents were evaluated by Fourier transform infrared spectroscopy. It is found that lithium salts show strong interaction with the main functional sulfone groups and sulfonic acid ester group, thus playing a vital role in the enhancement of the ionic conductivity and electrochemical stability of the solvent system. These sulfone-based solvents with high electrochemical stability are expected to become a new generation of a high-voltage organic electrolytic liquid system for lithium-ion batteries. PMID:26087246

  16. 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.

  17. High-Rate LiTi2(PO4)3@N-C Composite via Bi-nitrogen Sources Doping.

    PubMed

    Sun, Dan; Xue, Xia; Tang, Yougen; Jing, Yan; Huang, Bin; Ren, Yu; Yao, Yan; Wang, Haiyan; Cao, Guozhong

    2015-12-30

    Mesoporous LiTi2(PO4)3@nitrogen-rich doped carbon composites have been synthesized by a novel bi-nitrogen sources doping strategy. Tripolycyanamide (C3H6N6) and urea are proposed for the first time as both nitrogen and carbon sources to achieve a homogeneous nitrogen-doped carbon coating layer via an in situ method. The electrode delivers ultrahigh rate performance and outstanding cycling stability in lithium ion batteries (LIBs). In an organic electrolyte system, the electrode demonstrates high discharge capacities of 120 mAh g(-1) and 87 mAh g(-1) at 20C and 50C, respectively. Moreover, 89.5% of initial discharge capacity is retained after 1000 cycles at 10C. When used as an anode for aqueous LIBs, the electrode also demonstrates superior rate capability with the discharge capacity of 103 mAh g(-1) at 10C, corresponding to 84% of that at 1C. Outstanding cycling stability with capacity retention of 91.2% after 100 cycles at 30 mA g(-1) and 90.4% over 400 cycles at 150 mA g(-1) are also demonstrated. The uniform nitrogen-rich carbon coating and unique mesoporous structure play important roles in effectively suppressing the charge-transfer resistance and facilitating Li ion/electron diffusion, thus leading to the superior electrochemical properties. PMID:26633580

  18. Li doping effects on the upconversion luminescence of Yb3+/Er3+-doped ABO4 (A = Ca, Sr; B = W, Mo) phosphors

    NASA Astrophysics Data System (ADS)

    Kim, Jung Hwan; Choi, Haeyoung; Kim, Eun Ock; Noh, Hyeon Mi; Moon, Byung Kee; Jeong, Jung Hyun

    2014-12-01

    ABO4 (A = Ca, Sr; B = W, Mo):Er3+/Yb3+/Li+ phosphors tri-doped with different concentrations of Li+ ion ranging from 0 to 22.5 mol% were prepared by using a solid-state reaction method. And their upconversion (UC) luminescence properties were in estimated under a 975 nm laser-diode excitation. The four kinds of phosphors (CaWO4, CaMoO4, SrWO4, and SrMoO4) tri-doped with Er3+, Yb3+ and Li+ ions showed strong green UC emission peaks at 530 nm and 550 nm and weak red UC emission. The intensity of green UC emission of Li+ doped samples was several higher than that of Li+ un-doped samples due to the reduction of lattice constant and the local crystal field distortion around rare-earth ions. The optimum doping concentration of Li+ ions was investigated and the effects of Li+ concentration for UC emission intensity were studied in detail.

  19. 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.

  20. In situ XANES & XRD Study of interphasial reaction between uncharged Li2FeSiO4 cathode and LiPF6-based electrolyte

    NASA Astrophysics Data System (ADS)

    Arthur, Z.; Chiu, H. C.; Lu, X.; Chen, N.; Emond, V.; Demopoulos, G. P.; Jiang, D. T.

    2016-05-01

    In situ synchrotron radiation XANES and XRD have been carried out on Li2FeSiO4 cathode material in a lithium-ion-battery (LIB) cell. The evolution of the long range lattice structure and the local iron oxidation state has been observed at a charging rate of C/20 for the formation cycle for one Lithium extraction; additional ex situ measurements of the pristine cathode material were taken for comparison. The observed spontaneous interaction between the cathode and the fluorinated electrolyte and the impact of subsequent cycling are discussed.

  1. 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.

  2. 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.

  3. Ionic relaxation in PEO/PVDF-HFP-LiClO4 blend polymer electrolytes: dependence on salt concentration

    NASA Astrophysics Data System (ADS)

    Das, S.; Ghosh, A.

    2016-06-01

    In this paper, we have studied the effect of LiClO4 salt concentration on the ionic conduction and relaxation in poly ethylene oxide (PEO) and poly (vinylidene fluoride hexafluoropropylene) (PVDF-HFP) blend polymer electrolytes, in which the molar ratio of ethylene oxide segments to lithium ions (R  =  EO: Li) has been varied between 3 and 35. We have observed two phases in the samples containing low salt concentrations (R  >  9) and single phase in the samples containing high salt concentrations (R  ⩽  9). The scanning electron microscopic images indicate that there exists no phase separation in the blend polymer electrolytes. The temperature dependence of the ionic conductivity shows two slopes corresponding to high and low temperatures and follows Arrhenius relation for the samples containing low salt concentrations (R  >  9). The conductivity relaxation as well as the structural relaxation has been clearly observed at around 104 Hz and 106 Hz for these concentrations of the blended electrolytes. However, a single conductivity relaxation peak has been observed for the compositions with R  ⩽  9. The scaling of the conductivity spectra shows that the relaxation mechanism is independent of temperature, but depends on salt concentration.

  4. Study of SEI layer formed on graphite anodes in PC/LiBOB electrolyte using IR spectroscopy

    SciTech Connect

    Zhuang, G.V.; Xu, K.; Jow, T.R.; Ross Jr., P.N.

    2003-10-30

    Formation of the SEI layer on graphite anodes cycled in propylene carbonate (PC) lithium bis(oxolato)borate (LiBOB) electrolyte was studied by ex-situ Fourier Transform Infrared Spectroscopy (FTIR) analysis in the attenuated total reflection (ATR) mode. The results provide a more refined description of the composition than earlier analyses with x-ray photoelectron spectroscopy (XPS). The vibrational spectra clearly show that electrochemical reduction of the BOB anion is a part of the SEI formation chemistry. Carboxylate and/or oxalate functional groups derived from the BOB anion were the components assigned as the ''semicarbonate'' species in the C 1s XPS spectra of the SEI layer formed in LiBOB electrolyte. Reduction of the BOB anion changes the oxygen coordination around the B atom from tetrahedral BO4 to trigonal BO3, e.g., meta- or orthoborate. Based on the combination of electrochemical and FTIR data, we propose that the preferential reduction of the BOB anion versus the PC solvent molecule is responsible for the cyclability of graphite anodes in purely PC-based electrolyte.

  5. 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

    2016-03-01

    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. PMID:26862941

  6. Reduction of charge-transfer resistance at the solid electrolyte - electrode interface by pulsed laser deposition of films from a crystalline Li2PO2N source

    NASA Astrophysics Data System (ADS)

    West, William C.; Hood, Zachary D.; Adhikari, Shiba P.; Liang, Chengdu; Lachgar, Abdou; Motoyama, Munekazu; Iriyama, Yasutoshi

    2016-04-01

    Amorphous films deposited by pulsed laser deposition from a crystalline Li2PO2N target in a N2 ambient atmosphere (LiPON-PLD) have been examined as an approach to reduce the charge-transfer resistance at the electrode-solid electrolyte interface. Despite the relatively low ionic conductivity of ca. 1.5 × 10-8 S cm-1 at 25 °C, the amorphous LiPON-PLD films deposited between a LiMn1.485Ni0.45Cr0.05O4 (LNM) cathode and LiPON electrolyte resulted in sharply improved electrochemical performance in terms of charge-transfer resistance and CV profiles. Cells without a LiPON-PLD film had a charge-transfer resistance of 4470 Ω-cm2 compared to 760 and 960 Ω-cm2 for the sample with 17 nm and 31 nm thick LiPON-PLD films, respectively. The LiPON-PLD amorphous films show no evidence of the continuous planar sbnd Psbnd Nsbnd Psbnd N- backbone characteristic of the crystalline target material, but compared with LiPON prepared from radio frequency magnetron sputtering with Li3PO4 in a N2 atmosphere, the LiPON-PLD films were composed of a higher amount of triply coordinated P-N

  7. 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

  8. Dual field effects in electrolyte-gated spinel ferrite: electrostatic carrier doping and redox reactions

    NASA Astrophysics Data System (ADS)

    Ichimura, Takashi; Fujiwara, Kohei; Tanaka, Hidekazu

    2014-07-01

    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.

  9. Electric Field Induced Reversible Phase Transition in Li Doped Phosphorene: Shape Memory Effect and Superelasticity.

    PubMed

    Deng, Junkai; Chang, Zhenyue; Zhao, Tong; Ding, Xiangdong; Sun, Jun; Liu, Jefferson Zhe

    2016-04-13

    Phosphorene, the single-layer form of black phosphorus, as a new member of atomically thin material family, has unique puckered atomistic structure and remarkable physical and chemical properties. In this paper, we report a discovery of an unexpected electromechanical energy conversion phenomenon-shape memory effect-in Li doped phosphorene P4Li2, using ab initio density functional theory simulations. Two stable phases are found for the two-dimensional (2D) P4Li2 crystal. Applying an external electric field can turn on or off the unique adatom switches in P4Li2 crystals, leading to a reversible structural phase transition and thereby the shape memory effect with an tunable strain output as high as 2.06%. Our results demonstrate that multiple temporary shapes are attainable in one piece of P4Li2 material, offering programmability that is particularly useful for device designs. Additionally, the P4Li2 displays superelasticity that can generate a pseudoelastic tensile strain up to 6.2%. The atomic thickness, superior flexibility, excellent electromechanical strain output, the special shape memory phenomenon, and the programmability feature endow P4Li2 with great application potential in high-efficient energy conversion at nanoscale and flexible nanoelectromechanical systems. PMID:27043220

  10. Synthesis and TL characterization of Li2B4O7 doped with copper and manganese

    NASA Astrophysics Data System (ADS)

    Guarneros-Aguilar, C.; Cruz-Zaragoza, E.; Marcazzó, J.; Palomino-Merino, R.; Espinosa, J. E.

    2013-07-01

    Copper (Cu) and manganese (Mn) doped tissue equivalent Li2B4O7 were prepared by solid state sintering. The glow curves shows a high temperature peak at 222 °C for Li2B4O7:Cu and for Li2B4O7:Mn at 218 °C. Linear dose response is observed up to 140 Gy. With a thermal treatment at 125 °C, the first peak of the phosphors doped with copper (95 °C) and manganese (90 °C) disappears and the main TL peaks remain isolated. The dose rate dependence was studied by exposing the samples at doses of 25 Gy and 250 Gy. At low dose it was observed that the Li2B4O7:Cu TL response has non-dependence on dose rate, and at higher dose was observed that there is a dependence of the TL response with the different dose rate until of 30%. For the case of Li2B4O7:Mn, the TL response has non-dependence on dose rate at low dose or high dose.

  11. 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.

  12. Luminescence characteristics of Eu and Ti doped LiNaF2 phosphor

    NASA Astrophysics Data System (ADS)

    Puppalwar, S. P.; Dhoble, S. J.; Lochab, S. P.; Kumar, A.

    2012-08-01

    Polycrystalline low Z phosphors (Zeff = 9.54) LiNaF2:Eu and LiNaF2:Ti prepared by standard solid state diffusion method are studied for their photoluminescence (PL) and thermoluminescence (TL) characteristics. The PL emission spectra of the phosphors suggest the presence of Eu3+ and Ti4+ in the host compound occupying two different lattice sites. The intense emission observed in the spectrum of Eu doped phosphor is assigned to electronic transitions 5D0 →7F2 in Eu3+ ions. In Ti4+ doped phosphor the observed emission in the range 350-390 nm attributed to Ti4+ ions. The TL glow curves of these LiNaF2 phosphors exposed to γ-rays from 137Cs for different exposures are discussed for the first time. The thermoluminescence (TL) response in the 0.1-5.3 Gy dose range increased linearly with the increase in radiation dose. The whole glow curve displays a remarkable stability upon storage at room temperature. The TL sensitivity of the phosphors is compared with standard commercial TLD phosphor CaSO4:Dy and is found to be 5.37 times less in LiNaF2:Eu and 9.25 times less in LiNaF2:Ti phosphor.

  13. Defects Energetics and Electronic Properties of Li Doped ZnO: A Hybrid Hartree-Fock and Density Functional Study

    NASA Astrophysics Data System (ADS)

    Sun, Xu; Gu, You-song; Wang, Xue-qiang; Zhang, Yue

    2012-06-01

    The electronic properties and stability of Li-doped ZnO with various defects have been studied by calculating the electronic structures and defect formation energies via first-principles calculations using hybrid Hartree-Fock and density functional methods. The results from formation energy calculations show that Li pair complexes have the lowest formation energy in most circumstances and they consume most of the Li content in Li doped ZnO, which make the p-type conductance hard to obtain. The formation of Li pair complexes is the main obstacle to realize p-type conductance in Li doped ZnO. However, the formation energy of LiZn decreases as environment changes from Zn-rich to O-rich and becomes more stable than that of Li-pair complexes at highly O-rich environment. Therefore, p-type conductance can be obtained by Li doped ZnO grown or post annealed in oxygen rich atmosphere.

  14. 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.

  15. 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.

  16. A structured three-dimensional polymer electrolyte with enlarged active reaction zone for Li-O2 batteries

    NASA Astrophysics Data System (ADS)

    Bonnet-Mercier, Nadège; Wong, Raymond A.; Thomas, Morgan L.; Dutta, Arghya; Yamanaka, Keisuke; Yogi, Chihiro; Ohta, Toshiaki; Byon, Hye Ryung

    2014-11-01

    The application of conventional solid polymer electrolyte (SPE) to lithium-oxygen (Li-O2) batteries has suffered from a limited active reaction zone due to thick SPE and subsequent lack of O2 gas diffusion route in the positive electrode. Here we present a new design for a three-dimensional (3-D) SPE structure, incorporating a carbon nanotube (CNT) electrode, adapted for a gas-based energy storage system. The void spaces in the porous CNT/SPE film allow an increased depth of diffusion of O2 gas, providing an enlarged active reaction zone where Li+ ions, O2 gas, and electrons can interact. Furthermore, the thin SPE layer along the CNT, forming the core/shell nanostructure, aids in the smooth electron transfer when O2 gas approaches the CNT surface. Therefore, the 3-D CNT/SPE electrode structure enhances the capacity in the SPE-based Li-O2 cell. However, intrinsic instability of poly(ethylene oxide) (PEO) of the SPE matrix to superoxide (O2.-) and high voltage gives rise to severe side reactions, convincing us of the need for development of a more stable electrolyte for use in this CNT/SPE design.

  17. Effects of Li doping on the performance and environmental stability of solution processed ZnO thin film transistors

    NASA Astrophysics Data System (ADS)

    Nayak, Pradipta K.; Jang, Jongsu; Lee, Changhee; Hong, Yongtaek

    2009-11-01

    We report the effects of lithium (Li) doping on the performance and environmental stability of solution processed zinc oxide (ZnO) thin film transistors (TFTs). It was found that appropriate amount of Li doping significantly reduced the background conductivity of ZnO films and also improved the orientation of ZnO crystallites along the c-axis. A highest field-effect mobility of 3.07 cm2/V s was found for the 5 at. % Li-doped ZnO TFTs. However, 15 and 25 at. % Li-doped ZnO TFTs showed good environmental stability of Ion/Ioff ratio with reasonable field-effect mobility.

  18. {sup 7}Li NMR study of poly(p-phenylene) electrochemically doped with lithium

    SciTech Connect

    Shteinberg, V.G.; Shumm, B.A.; Zueva, A.F.

    1994-09-01

    Lithium ions in electrochemically doped poly(p-phenylene) (PPP) were studied by {sup 7}Li NMR. Two types of lithium cations exhibiting different mobility are found to exist. The fraction of more mobile cations increases with temperature but does not exceed 0.5. In the PPP{sup -}-Li{sup +} system, ion mobility is considerably lower than that found in the previously studied PPP{sup +}-AsF{sub 6}{sup -} (BF{sub 4}{sup -}) system, and up to 400 K no chemical reactions of polymer destruction occur.

  19. Growth and scintillation properties of Eu doped BaCl2/LiF eutectic scintillator

    NASA Astrophysics Data System (ADS)

    Kamada, Kei; Hishinuma, Kosuke; Kurosawa, Shunsuke; Yamaji, Akihiro; Shoji, Yasuhiro; Pejchal, Jan; Yokota, Yuui; Ohashi, Yuji; Yoshikawa, Akira

    2015-12-01

    Eu doped BaCl2/LiF eutectics were grown by the micro-pulling down method and their directionally solidified eutectic (DSE) system has been investigated. The grown eutectic showed main phases of cubic LiF and orthorhombic BaCl2. In these eutectics, the 399 nm emission of Eu2+ 4f5d was obtained. It shows the intrinsic decay time of about 410 ns. The light yield of the 1-mm-thick eutectic showed 7000 ph/5.5 MeV alpha-ray.

  20. 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.

  1. Life of superoxide in aprotic Li-O₂ battery electrolytes: simulated solvent and counter-ion effects.

    PubMed

    Scheers, J; Lidberg, D; Sodeyama, K; Futera, Z; Tateyama, Y

    2016-04-21

    Li-air batteries ideally make use of oxygen from the atmosphere and metallic lithium to reversibly drive the reaction 2Li + O2↔ Li2O2. Conceptually, energy throughput is high and material use is efficient, but practically many material challenges still remain. It is of particular interest to control the electrolyte environment of superoxide (O2*(-)) to promote or hinder specific reaction mechanisms. By combining density functional theory based molecular dynamics (DFT-MD) and DFT simulations we probe the bond length and the electronic properties of O2*(-) in three aprotic solvents - in the presence of Li(+) or the much larger cation alternative tetrabutylammonium (TBA(+)). Contact ion pairs, LiO2*, are favoured over solvent-separated ion pairs in all solvents, but particularly in low permittivity dimethoxyethane (DME), which makes O2*(-) more prone to further reduction. The Li(+)-O2*(-) interactions are dampened in dimethyl sulfoxide (DMSO), in relation to those in DME and propylene carbonate (PC), which is reflected by smaller changes in the electronic properties of O2*(-) in DMSO. The additive TBA(+) offers an alternative, more weakly interacting partner to O2*(-), which makes it easier to remove the unpaired electron and oxidation more feasible. In DMSO, TBA(+) has close to no effect on O2*(-), which behaves as if no cation is present. This is contrasted by a much stronger influence of TBA(+) on O2*(-) in DME - comparable to that of Li(+) in DMSO. An important future goal is to compare and rank the effects of different additives beyond TBA(+). Here, the results of DFT calculations for small-sized cluster models are in qualitative agreement with those of the DFT-MD simulations, which suggests the cluster approach to be a cost-effective alternative to the DFT-MD simulations for a more extensive comparison of additive effects in future studies. PMID:26947132

  2. Magnetic and dielectric studies of Li-Cu co-doped ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Vivek, S.; Ajith, S. K.; Chitralekha, C. S.; Nair, Swapna S.

    2016-05-01

    Room temperature ferromagnetism has been observed in Li-Cu co-doped ZnO nanoparticles prepared by sol-gel route. Our studies indicated that the observed ferromagnetism is a surface phenomenon which depends on oxygen vacancy and the nature of the dopants. Dependence of ferromagnetism on the annealing temperature indicated the role of oxygen vacancy, and the decrease in coercivity as the particle size increases indicates the surface dependence of ferromagnetism. It is found that the addition of dopants also enhanced ferromagnetism. Dielectric studies indicated an increase in dielectric constant as the doping concentration is increased.

  3. Impedance and structural studies on plasticized PCL-LiSO3CF3-SiO2 polymer electrolytes.

    PubMed

    Ng, B C; Wong, H Y; You, A H

    2014-07-01

    Plasticized polymer electrolytes in this study are consist of biodegradable polycaprolactone (PCL) as a host, ethylene carbonate (EC) as a plasticizer, lithium triflate (LiSO3CF3) as salt and nanocomposite silicon dioxide (SiO2) as filler. Solution cast technique is used in the preparation of the plasticized polymer electrolytes. The electrical properties of the plasticized polymer electrolytes with different composition of lithium salt, plasticizer and nano-sized filler are reported in this paper. Conductivity as high as 4.30 x 10(-3) S cm(-1) is obtained in ambient temperature. Ionic conductivity of the plasticized polymer electrolytes are measured using electrochemistry impedance spectroscopy (EIS). The structural and complex formations are studied by X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. The ionic conductivity result can be further verified and supported by XRD and FTIR reading in which the ionic conductivity is directly proportional to the amorphous phase behaviour of the sample. PMID:24758066

  4. Ionic conductivity in the crystalline polymer electrolytes PEO6:LiXF6, X = P, As, Sb.

    PubMed

    Stoeva, Zlatka; Martin-Litas, Isabelle; Staunton, Edward; Andreev, Yuri G; Bruce, Peter G

    2003-04-16

    Ionically conducting polymers (salts dissolved in a polymer matrix) are of great interest because they uniquely exhibit ionic conductivity in a soft but solid membrane. As such, they are critical to the development of devices such as all-solid-state lithium batteries. The established view of ionic conductivity in polymer electrolytes is that this occurs in amorphous materials above their glass transition temperature and that crystalline polymer electrolytes are insulators. In contrast, we show that three crystalline polymer electrolytes, poly(ethylene oxide)(6):LiXF(6), X = P, As, Sb, not only conduct but do so better than the analogous amorphous phases! It is also shown that the conductivities of all three 6:1 complexes are similar, consistent with the dimension of the bottlenecks to conduction derived from their crystal structures. An increase in ionic conductivity with reduction of molecular weight of the crystalline polymer electrolyte (from 2000 to 1000) is reported and shown to relate to the increase in crystallite size on reducing molecular weight. PMID:12683834

  5. Identity of Passive Film Formed on Aluminum in Li-ion BatteryElectrolytes with LiPF6

    SciTech Connect

    Zhang, Xueyuan; Devine, T.M.

    2006-09-01

    The passive film that forms on aluminum in 1:1 ethylene carbonate + ethylmethyl carbonate with 1.2M LiPF{sub 6} and 1:1 ethylene carbonate + dimethyl carbonate with 1.0M LiPF{sub 6} was investigated by a combination of electrochemical quartz crystal microbalance measurements (EQCM), electrochemical impedance spectroscopy (EIS), and x-ray photoelectron spectroscopy. During anodic polarization of aluminum a film of AlF{sub 3} forms on top of the air-formed oxide, creating a duplex, or two-layered film. The thickness of the AlF{sub 3} increases with the applied potential. Independent measurements of film thickness by EQCM and EIS indicate that at a potential of 5.5V vs. Li/Li{sup +}, the thickness of the AlF{sub 3} is approximately 1 nm.

  6. 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.

  7. Combined NMR and molecular dynamics modeling study of transport properties in sulfonamide based deep eutectic lithium electrolytes: LiTFSI based binary systems.

    PubMed

    Pauric, Allen D; Halalay, Ion C; Goward, Gillian R

    2016-03-01

    The trend toward Li-ion batteries operating at increased (>4.3 V vs. Li/Li(+)) voltages requires the development of novel classes of lithium electrolytes with electrochemical stability windows exceeding those of LiPF6/carbonate electrolyte solutions. Several new classes of electrolytes have been synthesized and investigated over the past decade, in the search for LIB electrolytes with improved properties (increased hydrolytic stability, improved thermal abuse tolerance, higher oxidation voltages, etc.) compared with the present state-of-the-art LiPF6 and organic carbonates-based formulations. Among these are deep eutectic electrolytes (DEEs), which share many beneficial characteristics with ionic liquids, such as low vapor pressure and large electrochemical stability windows, with the added advantage of a significantly higher lithium transference number. The present work presents the pulsed field gradient NMR characterization of the transport properties (diffusion coefficients and cation transport numbers) of binary DEEs consisting of a sulfonamide solvent and lithium bis(trifluoromethanesulfonyl)imide salt. Insights into the structural and dynamical properties, which enable one to rationalize the observed ionic conductivity behavior were obtained from a combination of NMR data and MD simulations. The insights thus gained should assist the formulation of novel DEEs with improved properties for LIB applications. PMID:26871506

  8. Ionic conductivity studies in crystalline PVA/NaAlg polymer blend electrolyte doped with alkali salt KCl

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    Potassium Chloride (KCl) doped poly(vinyl alcohol) (PVA)/sodium alginate (NaAlg) in 60:40 wt% polymer blend electrolytes were prepared by solution casting method. The complexation of KCl with host PVA/NaAlg blend is confirmed by FTIR and UV-Vis spectra. The XRD studies show that the crystallinity of the prepared blends increases with increase in doping. The dc conductivity increases with increase in dopant concentration. Temperature dependent dc conductivity shows an Arrhenius behavior. The dielectric properties show that both the dielectric constant and dielectric loss increases with increase in KCl doping concentration and decreases with frequency. The cole-cole plots show a decrease in bulk resistance, indicates the increase in ac conductivity, due to increase in charge carrier mobility. The doping of KCl enhances the mechanical properties of PVA/NaAlg, such as Young's modulus, tensile strength, stiffness.

  9. 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.

  10. Luminescence spectra of chromium-doped LiGaO 2 crystals as indicator of their phase heterogeneity

    NASA Astrophysics Data System (ADS)

    Meylman, Mikhail L.

    2006-02-01

    The luminescent properties of chromium-doped LiGaO2 single crystals grown from melt by Cz pulling technique are considered and compared with similar data for the other stable crystalline compounds in Li2O-Ga2O3 oxide system. It is proposed that co-crystallization of large LiGaO2 single crystal and a great number of LiGa5O8 spinel microcrystallites of nano scale dimensions is the key cause for appearance of numerous inclusions observed in LiGaO2 plates used as substrates at the III nitride films epitaxial growth.

  11. First Principles Study of Electrochemical and Chemical Stability of the Solid Electrolyte-Electrode Interfaces in All-Solid-State Li-Ion Batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Yizhou; He, Xingfeng; Mo, Yifei

    All-solid-state Li-ion battery is a promising next-generation energy-storage technology. Using novel ceramic solid electrolyte materials, all-solid-state battery has advantages of intrinsic safety and high energy density compared to current Li-ion batteries based on organic liquid electrolyte. However, the power density achieved in all-solid-state battery is still unsatisfactory. The high interfacial resistance at electrode-electrolyte interface is one of the major limiting factors. Here we demonstrated a computational approach based on first principles calculation to systematically investigate the chemical and electrochemical stability of solid electrolyte materials, and provide insightful understanding of the degradation and passivation mechanisms at the interface. Our calculation revealed that the intrinsic stability of solid electrolyte materials and solid electrolyte-electrode interfaces is limited and the formation of interphase layers are thermodynamically favorable. Our study demonstrated a computational scheme to evaluate the electrochemical and chemical stability of the solid interfaces. Our newly gained understanding provided principles for developing solid electrolyte materials with enhanced stability and for engineering interfaces in all-solid-state Li-ion batteries. This work was supported by Office of Energy Efficiency and Renewable Energy (DE-EE0006860).

  12. Investigation of solid electrolyte interface (SEI) film on LiCoO2 cathode in fluoroethylene carbonate (FEC)-containing electrolyte by 2D correlation X-ray photoelectron spectroscopy (XPS)

    NASA Astrophysics Data System (ADS)

    Park, Yeonju; Shin, Su Hyun; Hwang, Hoon; Lee, Sung Man; Kim, Sung Phil; Choi, Hyun Chul; Jung, Young Mee

    2014-07-01

    The effects of fluoroethylene carbonate (FEC) on the electrochemical performance of the LiCoO2 cathode were investigated by galvanostatic charge-discharge testing and cyclic voltammetry (CV). It was found that FEC has a positive effect on cycling stability and also improves cell performance. We also studied solid electrolyte interface (SEI) film on the LiCoO2 cathode, using X-ray photoelectron spectroscopy (XPS) and 2D correlation spectroscopy. The 2D correlation XPS spectra showed that, initially, the polyvinylidene fluoride (PVdF) binder and electrolyte components are decomposed, after which SEI components are formed on the LiCoO2 cathode surface. In the FEC-containing electrolyte, the polycarbonate components are more abundant than in the FEC-free electrolyte. The formed carbonates in SEI film can act as Li+-conducting materials in reducing the electrode/electrolyte interfacial impedance. This hypothesis is supported by the results of an electrochemical impedance spectrum (EIS) analysis.

  13. Application of electrolyte using novel ionic liquid to Si thick film anode of Li-ion battery

    NASA Astrophysics Data System (ADS)

    Usui, Hiroyuki; Yamamoto, Yoshihisa; Yoshiyama, Kazuhide; Itoh, Toshiyuki; Sakaguchi, Hiroki

    An applicability of a novel ionic liquid, consisting of 1-methoxyethoxymethyl(tri- n-butyl)phosphonium cation and bis(trifluoromethanesulfonyl)amide anion, was investigated as an electrolyte of Li-ion battery using a thick film electrode of Si prepared by a gas-deposition method. The electrochemical properties in the novel ionic liquid were compared to those in a commercial ionic liquid and a typical organic solvent of propylene carbonate. The initial discharge capacity of 3450 mAh g -1 and excellent cycling performance were achieved in the novel ionic liquid. The novel ionic liquid was confirmed to effectively suppress a collapse and an electrical isolation of the Si thick film induced by pulverization during charge-discharge cycling. The excellent performance is possibly attributed to more effective desolvation of Li ions from the anions due to its lower dielectric constant compared with the propylene carbonate solvent.

  14. 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.

  15. Field assisted sintering of dense Al-substituted cubic phase Li7La3Zr2O12 solid electrolytes

    NASA Astrophysics Data System (ADS)

    Zhang, Yanhua; Chen, Fei; Tu, Rong; Shen, Qiang; Zhang, Lianmeng

    2014-12-01

    High performance lithium ion conducting Li7La3Zr2O12 solid electrolytes are prepared for the first time by field assisted sintering technology (FAST). The effect of sintering temperature on the phase compositions, microstructure and Li ionic conductivity is systematically investigated. The results show that pure cubic phase LLZO can be obtained at a range of temperatures from 1100 to 1180 °C for no more than 10 min. For the sample sintered at 1150 °C, a maximum relative density of 99.8% with a total ionic conductivity as high as 5.7 × 10-4 S cm-1 are obtained at room temperature. This value is the highest among the present research. Compared with the traditional preparation methods, the current FAST is very promising to obtain high performance LLZO for its advantages of very short sintering time, a single preparation step of reaction-densification processing, and relatively lower sintering temperature.

  16. Thermal and transport properties of the polymer electrolyte based on poly(vinyl alcohol)-LiOH-H2O

    NASA Astrophysics Data System (ADS)

    Fernández, M. E.; Delgado, I.; Diosa, J. E.; Vargas, R. A.

    2005-08-01

    Alkaline solid electrolyte membranes, based on the poly(vinyl alcohol) (PVAL), lithium hydroxide (LiOH) and water with various salt concentrations have been synthesized. These systems have anhydridous ionic conductivity () as high as 2,9 × 10-4 Scm-1 at room temperature and show a linear dependence of ln() with 1/T below 80 °C. The thermal analysis indicated three transformations in the blends: at 205, 150 and -125 °C, associated with decompositions, melting point and glass transition of the polymer blends, respectively. The X-ray spectra for the samples at room temperature show a peak at about 2 = 20° for all salt concentrations and whose intensity depends on the amorphous character of the system. The results are discussed in terms of the high mobility of the Li+ ions in the amorphous phase of the complex.

  17. Thermoluminescence Study of Gamma Irradiated Cr-Doped LiF Phosphors

    NASA Astrophysics Data System (ADS)

    Kumar, Satinder; Gathania, A. K.; Vij, Ankush; Kumar, Ravi

    2016-06-01

    We have synthesized Cr-doped LiF phosphors by using modified co-precipitation. X-ray diffraction study confirms the single-phase cubic structure up to 0.05 mol.% of Cr in LiF; afterwards, a secondary phase of formation was observed. The field emission scanning electron microscope (FESEM) images revealed micro-cubic surface morphology of samples. The thermoluminescent (TL) behavior of the samples studied after irradiating them with gamma rays in the dose range 0.1-30 kGy. The TL glow curve of Cr-doped LiF comprises a prominent peak observed at 407 K and a broad band ranging from 448 K to 512 K at a fixed gamma dose of 10 kGy. The shape of the TL glow curve remained similar at all concentrations of Cr in LiF; however, TL intensity was found to vary with Cr concentration, and Cr (0.02 mol.%)-doped LiF sample exhibit highest TL response. The glow curve of the optimized sample as a function of gamma irradiation dose within the range 0.1-30 kGy shows an almost linear increase in TL intensity of the main glow peak up to 10 kGy, and afterwards it decreases. Further, at the high dose of 30 kGy, the intensity of the prominent TL glow peak at 407 K decreases and another broad peak starts growing at 468 K signifying the formation of new trapping sites. The kinetic parameters, namely activation energy, order of kinetics, and frequency factor of the optimized sample were evaluated by using Chen's peak shape method and glow curve deconvolution (GCD) functions based on Kitti's equations.

  18. 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. PMID:27071463

  19. Uranium doped LiSAF as a precursor for a 229 Th nuclear clock experiment

    NASA Astrophysics Data System (ADS)

    Meyer, Edmund; Hehlen, Markus; Barker, Beau; Collins, Lee; Zhao, Xinxin

    2016-05-01

    We experimentally and numerically study the simple idea of growing 233 U doped LiSAF crystals. The micro-pulling-down technique is used to grow U:LiSAF single crystals with a high number density of U ions. The crystals are in the shape of rods that are geometrically well matched for imaging onto the spectrophotometer input slit. Growth is performed in an RF-heated chamber under argon inert atmosphere at elevated pressure. This reduces the evaporation of LiF and AlF3 from the melt and crystal surface during growth which otherwise tends to degrade the crystal quality. Through physical arguments and robust numerical calculation we determine the oxidation state of the U ion to likely be trivalent and occupying the Sr site. Charge compensation is numerically studied through F interstitials and Li vacancies. We determine the energetically most favorable state for U:LiSAF and investigate the effects upon α-decay of 233 U to 229 Th, which ~ 2% of the time is in the excited isomeric state. Additional charge compensation mechanisms are needed to accommodate the Th4+ ground oxidation state and we investigate F interstitial as well as Li vacancy. The band structure is calculated and analyzed for select cases.

  20. 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.

  1. Influence of 15-crown-5 additive to a liquid electrolyte on the performance of Li/CFx - Systems at temperatures up to -50 °C

    NASA Astrophysics Data System (ADS)

    Ignatova, A. A.; Yarmolenko, O. V.; Tulibaeva, G. Z.; Shestakov, A. F.; Fateev, S. A.

    2016-03-01

    The additive of 15-crown-5 for liquid electrolyte for primary Li/CFx cells is proposed. In their presence the cells with 1 M LiBF4 in GBL and 1 M LiPF6 in EC/DMC/EMC are workable at low temperatures. Their discharge capacities are 140 and 110 mAh g-1 at -45 ÷ -50 °C respectively. The 15-crown-5 additive probably is adsorbed on electrodes surfaces and form Li+ conducting layers. This mechanism approved by quantum-chemical modeling.

  2. Transport Properties of LiTFSI-Acetamide Room Temperature Molten Salt Electrolytes Applied in an Li-Ion Battery

    NASA Astrophysics Data System (ADS)

    Yang, Chao-Chen; Hsu, Hsin-Yi; Hsu, Chen-Ruei

    2007-11-01

    In the present work some transport properties of the binary room temperature molten salt (RTMS) lithium bis(trifluoromethane sulfone)imide (LiTFSI)-acetamide [LiN(SO2CF3)2-CH3CONH2], applied in an Li-ion battery, have been investigated. The phase diagram was determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The result reveals that the binary RTMS has an eutectic point at 201 K and the 30 mol% LiTFSI composition. The electric conductivity was measured using a direct current computerized method. The result shows that the conductivities of the melts increase with increasing temperature and acetamide content. The densities of all melts decrease with increasing temperature and acetamide content. The equivalent conductivities were fitted by the Arrhenius equation, where the activation energies were 18.15, 18.52, 20.35, 25.08 kJ/mol for 10, 20, 30, 40 mol% LiTFSI, respectively. Besides the relationships between conductivity, density composition and temperature, of the ion interaction is discussed.

  3. Li-doped B2C graphene as potential hydrogen storage medium

    NASA Astrophysics Data System (ADS)

    An, Hui; Liu, Chun-sheng; Zeng, Zhi; Fan, Chao; Ju, Xin

    2011-04-01

    Based on first-principles density functional theory, we show that Li-doped B2C graphene can serve as a high-capacity hydrogen storage medium with the gravimetric density of 7.54 wt %. The present results indicate that the strong binding of Li onto the substrate comes from the hybridizations of B 2p and C 2p orbitals with the partial occupancy of Li 2p orbitals. Both the polarization mechanism and the orbital hybridizations contribute to the adsorption of H2 molecules and the resulting adsorption energy is in the range of 0.12-0.22 eV/H2. The system reported here is favorable for the reversible hydrogen adsorption/desorption at the room temperature.

  4. 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.

  5. 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.

  6. Stability of the LiMn2O4 surface in a LiPF6-based non-aqueous electrolyte studied by in-situ atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Kitta, Mitsunori; Kohyama, Masanori

    2016-06-01

    Investigation of the surface stability of electrode materials in a liquid electrolyte is significantly important for understanding the deterioration of stored Li-ion battery cells. Here, we examined LiMn2O4 surfaces in a LiPF6-based non-aqueous electrolyte by in-situ atomic force microscopy. A LiMn2O4(111) surface sample with a well-defined atomically-flat structure was prepared from a MnO(111) wafer. Although the surfaces of non-exposed or dry-air-exposed samples did not change in a typical electrolyte such as LiPF6 dissolved in propylene carbonate, the surface morphology of an air-exposed sample greatly changed under the same condition. Transmission electron microscopy observation revealed that the surface roughness is increased by the dissolution of one or two atomic layers of LiMn2O4-crystal surfaces in the electrolyte. The adsorbed water on the air-exposed surface is the origin of this phenomenon.

  7. 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.

  8. Effect of bismuth doping on the physical properties of La-Li-Mn-O manganite

    NASA Astrophysics Data System (ADS)

    Yanapu, Kalyana Lakshmi; Samatham, S. Shanmukharao; Kumar, Devendra; Ganesan, V.; Reddy, P. Venugopal

    2016-03-01

    The effects of bismuth doping at La site on magnetic, electrical and thermopower properties of LaLiMnO3 manganites have been investigated. The substitution of Bi ion leads to the weakening of ferromagnetic ordering at low temperature, and Curie temperature ( T C) decreases with increase in Bi content. Interestingly, a dramatic increase in the magnitude of Seebeck coefficient at low temperature is observed in Bi-doped samples which might find potential application as thermoelectric. The results are attributed to the combined effect of the disorder and antiferromagnetic interaction induced by Bi doping. Both ρ( T) and S( T) data in the high-temperature region are discussed using small polaron hopping model.

  9. 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.

  10. 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.

  11. Evaluation of the physi- and chemisorption of hydrogen in alkali (Na, Li) doped fullerenes

    DOE PAGESBeta

    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 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

  12. 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.

  13. LiTFSI in 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)amide: a possible electrolyte for ionic liquid based lithium ion batteries.

    PubMed

    Lahiri, Abhishek; Schubert, Thomas J S; Iliev, Boyan; Endres, Frank

    2015-05-01

    In this communication, we show that the combination of 1 M lithium bis(trifluoromethylsulfonyl)amide and 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)amide (LiTFSI/[Py1,4]FSI) can be regarded as a possible stable electrolyte for IL based lithium ion batteries. We compare the charge-discharge results with the electrolyte 1 M LiTFSI in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py1,4]TFSI) on an electrodeposited Ge electrode and show using a charge-discharge analysis and Raman spectroscopy that 1 M LiTFSI/[Py1,4]FSI is advantageous in maintaining the charge capacity as well as electrolyte stability at high current densities. PMID:25868690

  14. 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

  15. Allylic ionic liquid electrolyte-assisted electrochemical surface passivation of LiCoO2 for advanced, safe lithium-ion batteries.

    PubMed

    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

  16. 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.

  17. First-principles assessment of hole transport in pure and Li-doped NiO.

    PubMed

    Alidoust, Nima; Carter, Emily A

    2015-07-21

    Alloying nickel oxide (NiO) with lithium oxide (Li2O) at high Li concentrations may reduce NiO's band gap and expand its use as a light absorber in photocatalytic and tandem dye-sensitized solar cell technologies. In this work, we evaluate the viability of this alloy as a p-type hole transport material. We use embedded cluster models, along with unrestricted Hartree-Fock and complete active space self-consistent field theories, to study the impact of alloying on polaronic transport of holes. Our calculated energy barrier for hole transfer in undoped NiO is in excellent agreement with the experimental value of ∼0.1 eV. We predict that hole transport in NiO is anisotropic and mostly confined parallel to the (111) ferromagnetic planes. Applying the same model to Li-doped NiO indicates that isolated Li ions do not introduce free holes into NiO samples. However, free holes can be created in the homogeneous Li0.125Ni0.875O alloy, in which the Li concentration is very high. Our kinetic Monte Carlo calculations show that hole mobility in this alloy is lower than in undoped NiO. However, the additional free holes and the predicted lower band gap of Li0.125Ni0.875O should increase hole conductivity compared to NiO upon alloy formation. Therefore, Li0.125Ni0.875O alloys have potential for use as a hole transporter, as well as a sunlight absorber, in a variety of solar energy applications. PMID:26100512

  18. Electrolytic reduction of a simulated oxide spent fuel and the fates of representative elements in a Li2O-LiCl molten salt

    NASA Astrophysics Data System (ADS)

    Park, Wooshin; Choi, Eun-Young; Kim, Sung-Wook; Jeon, Sang-Chae; Cho, Young-Hwan; Hur, Jin-Mok

    2016-08-01

    A series of electrolytic reduction experiments were carried out using a simulated oxide spent fuel to investigate the reduction behavior of elements in a mixed oxide condition and the fates of elements in the reduction process with 1.0 wt% Li2O-LiCl. It was found out that 155% of the theoretical charge was enough to reduce the simulated. Te and Eu were expected to possibly exist in the precipitate and on the anode surface, whereas Ba and Sr showed apparent dissolution behaviors. Rare earths showed relatively low metal fractions from 28.2 to 34.0% except for Y. And the solubility of rare earths was observed to be low due to the low concentration of Li2O. The reduction of U was successful as expected showing 99.8% of a metal fraction. Also it was shown that the reduction of ZrO2 would be effective when a relatively small amount was included in a metal oxide mixture.

  19. 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.

  20. 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).

  1. 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

  2. Operando observation of the gold-electrolyte interface in Li-O2 batteries.

    PubMed

    Gittleson, Forrest S; Ryu, Won-Hee; Taylor, André D

    2014-11-12

    Observing the cathode interface in Li-O2 batteries during cycling is necessary to improve our understanding of discharge product formation and evolution in practical cells. In this work a gold electrode surface is monitored by operando surface-enhanced Raman spectroscopy during typical discharge and charge cycling. During discharge, we observe the precipitation of stable and reversible lithium superoxide (LiO2), in contrast to reports that suggest it is a mere intermediate in the formation of lithium peroxide (Li(2)O2). Some LiO2 is further reduced to Li(2)O2 producing a coating of insulating discharge products that renders the gold electrode inactive. Upon charging, a superficial layer of these species (∼ 1 nm) are preferentially oxidized at low overpotentials (<0.6 V), leaving residual products in poor contact with the electrode surface. In situ electrochemical impedance spectroscopy is also used to distinguish between LiO2 and Li(2)O2 products using frequency-dependent responses and to correlate their reduction and oxidation potentials to the accepted mechanism of Li(2)O2 formation. These operando and in situ studies of the oxygen electrode interface, coupled with ex situ characterization, illustrate that the composition of discharge products and their proximity to the catalytic surface are important factors in the reversibility of Li-O2 cells. PMID:25318060

  3. Effect of Al2O3 on crystallinity and conductivity of PVA-PEO-EC-LiCF3SO3 blend electrolyte system

    NASA Astrophysics Data System (ADS)

    Joge, Prajakta N.; Kanchan, D. K.; Sharma, Poonam L.

    2014-04-01

    In the present study, the PVA-PEO-EC-LiCF3SO3 polymer electrolytes are prepared using solution cast technique for different concentrations of Al2O3 ranging from 2 to 10 wt%. The study deals with the investigation of the influence of Al2O3 concentration on the electrical properties and crystallinity of the polymer electrolytes. The conductivity studies are carried out using impedance spectroscopic analysis and the variation in crystallinity is investigated using XRD technique.

  4. 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.

  5. Surface Reactivity of a Carbonaceous Cathode in a Lithium Triflate/Ether Electrolyte-Based Li-O2 Cell.

    PubMed

    Carboni, Marco; Brutti, Sergio; Marrani, Andrea G

    2015-10-01

    Li-O2 batteries are currently one of the most advanced and challenging electrochemical systems with the potential to largely overcome the performances of any existing technology for energy storage and conversion. However, these optimistic expectations are frustrated by the still inadequate understanding of the fundamentals of the electrochemical/chemical reactions occurring at the cathode side, as well as within the electrolyte and at the three-phase interface. In this work, we illustrate the evolution of the morphology and composition of a carbonaceous cathode in the first discharge/charge in a Li-O2 cell with an ether-based electrolyte by X-ray photoemission spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. Experiments have been carried out ex situ on electrodes recuperated from electrochemical cells stopped at various stages of galvanostatic discharge and charge. Apparently, a reversible accumulation and decomposition of organic and inorganic precipitates occurs upon discharge and charge, respectively. These precipitations and decompositions are likely driven by electrochemical and chemical parasitic processes due to the reactivity of the cathode carbonaceous matrix. PMID:26375042

  6. 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.

  7. Effects of Ho3+ and Yb3+ doping concentrations and Li+ co-doping on the luminescence of GdVO4 powders

    NASA Astrophysics Data System (ADS)

    Gavrilović, Tamara V.; Jovanović, Dragana J.; Trandafilović, Lidija V.; Dramićanin, Miroslav D.

    2015-07-01

    We present the structural and luminescent properties of Ho3+/Yb3+-doped GdVO4 and Li+-co-doped GdVO4:Ho3+/Yb3+ powder phosphors. The materials were prepared by high-temperature solid state method with different concentrations (between 0.5 and 2 mol%) of dopant Ho3+ emitting ions and different concentrations (between 5 and 20 mol%) of sensitizer Yb3+ ions. The dopant ions provided the material with intense luminescence emission; green emissions (centered at 542 nm from 5F4,5S2 → 5I8 electronic transition of Ho3+ ions) resulted upon ultraviolet excitation, and red (centered at 659 nm from 5F5 → 5I8 electronic transition of Ho3+ ions) upon near-infrared excitation. The co-doped materials were obtained under identical experimental conditions by adding Li+ ions (5, 7.5, 10, and 15 mol%). The powders co-doped with 7.5 mol% Li+ ions showed a downconversion emission intensity more than twice as high as the samples without Li+ co-doping. In upconversion, an equal intensification of emission was achieved with co-doping with 10 mol% Li+. The influences of Ho3+/Yb3+ concentration ratio and Li+ co-doping level on emission color and emission branching was investigated and analyzed for both downconversion and upconversion emission. Increasing Yb3+ concentration was found to increase the share of dominant emission (green) in downconversion, but decreased the share of dominant emission (red) in upconversion.

  8. Enhanced mobility of Li-doped ZnO thin film transistors fabricated by mist chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Jeon, Hye-ji; Lee, Seul-Gi; Kim, H.; Park, Jin-Seong

    2014-05-01

    Mist chemical vapor deposition (mist-CVD)-processed, lithium (Li)-doped ZnO thin film transistors (TFTs) are investigated. Li doping significantly increases the field-effect mobility in TFTs up to ˜100 times greater than that of undoped ZnO. The addition of Li into mist-CVD-grown ZnO semiconductors leads to improved film quality, which results from the enhanced crystallinity and reduced defect states, including oxygen vacancies. Our results suggest that Li doping of ZnO-based oxide semiconductors could serve as an effective strategy for high-performance, mist-CVD-processed oxide TFTs with low-cost and low-temperature fabrication.

  9. Raman scattering and the evolution of polar order in Li-doped and Nb-doped KTaO3

    NASA Astrophysics Data System (ADS)

    Calvi, P.; Camagni, P.; Giulotto, E.; Rollandi, L.

    1996-03-01

    A comparative study of first-order Raman scattering in K0.984Li0.016TaO3 and KTa0.976Nb0.024O3 single crystals has been performed. The soft-phonon line shows marked differences in the two systems, revealing a distinctive behavior with regard to the scale of polar order. Analysis of the low-frequency spectrum allows for an estimate of the polar correlation length in the Li-doped sample; this is limited to the nanometric scale, in agreement with the view of a dipole-glass transition. No evidence of a similar situation is found in the Nb-doped sample, where the general trend of soft-mode frequencies and intensities suggests a transition to a state of long-range order, for the quoted concentration. The intensities of the hard-phonon spectra and the TO4 linewidth are shown to confirm the different evolution of the polar transition in the two systems.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Dual-doping to suppress cracking in spinel LiMn2O4: a joint theoretical and experimental study.

    PubMed

    Zhang, Zhifeng; Chen, Zhenlian; Wang, Guangjin; Ren, Heng; Pan, Mu; Xiao, Lingli; Wu, Kuicheng; Zhao, Liutao; Yang, Jianqing; Wu, Qingguo; Shu, Jie; Wang, Dongjie; Zhang, Hongli; Huo, Ni; Li, Jun

    2016-03-01

    Electrochemical cycling stabilities were compared for undoped and Al/Co dual-doped spinel LiMn2O4 synthesized by solid state reactions. We observed the suppression of particle fracture in Al/Co dual-doped LiMn2O4 during charge/discharge cycling and its distinguishable particle morphology with respect to the undoped material. Systematic first-principles calculations were performed on undoped, Al or Co single-doped, and Al/Co dual-doped LiMn2O4 to investigate their structural differences at the atomistic level. We reveal that while Jahn-Teller distortion associated with the Mn(3+)O6 octahedron is the origin of the lattice strain, the networking -i.e. the distribution of mixed valence Mn ions - is much more important to release the lattice strain, and thus to alleviating particle cracking. The calculations showed that the lattice mismatching between Li(+) intercalation and deintercalation of LiMn2O4 can be significantly reduced by dual-doping, and therefore also the volumetric shrinkage during delithiation. This may account for the near disappearance of cracks on the surface of Al/Co-LiMn2O4 after 350 cycles, while some obvious cracks have developed in undoped LiMn2O4 at similar particle size even after 50 cycles. Correspondingly, Al/Co dual-doped LiMn2O4 showed a good cycling stability with a capacity retention of 84.1% after 350 cycles at a rate of 1C, 8% higher than the undoped phase. PMID:26879071

  15. 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.

  16. 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.

  17. Improved sensitivity of nonvolatile holographic storage in triply doped LiNbO(3):Zr,Cu,Ce.

    PubMed

    Liu, Fucai; Kong, Yongfa; Ge, Xinyu; Liu, Hongde; Liu, Shiguo; Chen, Shaolin; Rupp, Romano; Xu, Jingjun

    2010-03-15

    We have designed and grown triply doped LiNbO(3):Zr,Cu,Ce crystal and investigated its characteristics of nonvolatile holographic storage. It's observed that the photorefractive sensitivity of LiNbO(3):Zr,Cu,Ce has improved to 0.099 cm/J, which is about one order of magnitude larger than that of congruent LiNbO(3):Cu,Ce. And LiNbO(3):Zr,Cu,Ce also has high suppression to light-induced scattering. Our results indicated that triply doped LiNbO(3):Zr,Cu,Ce is an excellent candidate for nonvolatile holographic data storage. PMID:20389656

  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. Chemical reactivity of aprotic electrolytes on a solid Li2O2 surface: screening solvents for Li-air batteries

    NASA Astrophysics Data System (ADS)

    Laino, Teodoro; Curioni, Alessandro

    2013-09-01

    Nowadays, simulation techniques are routinely used to generate accurate models of the structures of crystalline and amorphous solids, to study surfaces, defects and the properties of complex systems, and to screen possible candidate materials for the most diverse types of technological applications. The screening of novel molecular structures has been so far pursued by calculation of intrinsic properties with first-principle methods. Still, the use of intrinsic properties as scoring functions may not always be optimal for systems of high complexity. In these cases, increasingly detailed and realistic simulations that take into account the interaction with the surrounding molecules are of crucial importance. In this paper, we present an effective way to screen different solvents with respect to their chemical stability versus Li2O2 solid particles. To achieve this, the minimum energy paths for different types of reactions of a series of aprotic solvents (acetonitrile and pivalonitrile, dimethyl sulphoxide, N-methyl-2-pyrrolidone and some of its derivatives, penta ethylene glycol (PEG-5) and a fluorinated derivative) with solid Li2O2 are computed and reported. From these data, we can extract the reaction energy barriers, which compare extremely well with the available experimental data and offer a convenient way for screening and designing suitable solvents for Li-air batteries from first-principle calculations.

  20. Enhanced electrochemical performance of LiNi0.5Mn1.5O4 cathode using an electrolyte with 3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane

    NASA Astrophysics Data System (ADS)

    Luo, Ying; Lu, Taolin; Zhang, Yixiao; Yan, Liqin; Xie, Jingying; Mao, Samuel S.

    2016-08-01

    A new electrolyte based on fluorinated 3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane (F-EPE) solvent is studied in LiNi0.5Mn1.5O4/Li cells. The electrochemical stability of the electrolyte with 10% F-EPE is carried out by linear sweep voltammetry and electrochemical floating test. These results indicate that the electrolyte with F-EPE has an oxidation potential of more than 5.2 V vs. Li+/Li, which is higher than that without F-EPE and enlarges the oxidative window of electrolyte. A thin and uniform SEI layer is formed on the surface of LiNi0.5Mn1.5O4 cathode by using electrolyte with F-EPE, leads to an improvement in the electrochemical performance, validated by charge-discharge tests, EIS, SEM, TEM, and XPS analysis.

  1. 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.

  2. 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.

  3. 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.

  4. Superior electrochemical performance of LiCoO2 electrodes enabled by conductive Al2O3-doped ZnO coating via magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Dai, Xinyi; Zhou, Aijun; Xu, Jin; Yang, Bin; Wang, Liping; Li, Jingze

    2015-12-01

    A conductive Al2O3-doped ZnO (AZO) layer is coated directly on the LiCoO2 (LCO) porous composite electrode by magnetron sputtering of an AZO target, offering more efficient electron transfer and a stabilized interface layer. Up to 90% of the initial capacity of the AZO-coated electrode can be retained (173 mAh g-1) after 150 cycles between 3.0 and 4.5 V vs. Li/Li+. Meanwhile, the rate performance is remarkably improved showing a reversible capacity of 112 mAh g-1 at 12 C. The formation of amorphous solid electrolyte interface (SEI) observed on the uncoated LCO electrode is effectively impeded on the AZO-coated one. Acting as an intermediate barrier, the AZO layer can prevent chemical dissolution of the active materials by forming a thin passivation layer on the electrode surface containing some metal fluorides which are chemically inactive and ionically conductive. The positive role of the AZO coating is still effective under a more severe condition tested with an upper cut-off potential of 4.7 V.

  5. Component-/structure-dependent elasticity of solid electrolyte interphase layer in Li-ion batteries: Experimental and computational studies

    NASA Astrophysics Data System (ADS)

    Shin, Hosop; Park, Jonghyun; Han, Sangwoo; Sastry, Ann Marie; Lu, Wei

    2015-03-01

    The mechanical instability of the Solid Electrolyte Interphase (SEI) layer in lithium ion (Li-ion) batteries causes significant side reactions resulting in Li-ion consumption and cell impedance rise by forming further SEI layers, which eventually leads to battery capacity fade and power fade. In this paper, the composition-/structure-dependent elasticity of the SEI layer is investigated via Atomic Force Microscopy (AFM) measurements coupled with X-ray Photoelectron Spectroscopy (XPS) analysis, and atomistic calculations. It is observed that the inner layer is stiffer than the outer layer. The measured Young's moduli are mostly in the range of 0.2-4.5 GPa, while some values above 80 GPa are also observed. This wide variation of the observed elastic modulus is elucidated by atomistic calculations with a focus on chemical and structural analysis. The numerical analysis shows the Young's moduli range from 2.4 GPa to 58.1 GPa in the order of the polymeric, organic, and amorphous inorganic components. The crystalline inorganic component (LiF) shows the highest value (135.3 GPa) among the SEI species. This quantitative observation on the elasticity of individual components of the SEI layer must be essential to analyzing the mechanical behavior of the SEI layer and to optimizing and controlling it.

  6. Effect of LiCl doping on dielectric behavior of copper-zinc ferrite system

    NASA Astrophysics Data System (ADS)

    Lipare, A. Y.; Vasambekar, P. N.; Vaingankar, A. S.

    2004-08-01

    Polycrystalline soft ferrite samples were prepared with chemical formula, Zn xCu 1- xFe 2O 4 ( x=0.30,0.50,0.70,0.80 and 0.90) doped with controlled amount of lithium chloride (LiCl) by standard ceramic technique. The samples were characterized by XRD, IR absorption techniques. X-ray diffraction studies of the compositions reveal formation of single-phase cubic structure. The values of lattice constant decrease as doping percentage of LiCl is increased from 0.01% to 0.10%. The presence of chlorine ions is confirmed by IR absorption peak in spectrum near 650 cm-1 for all the samples. The investigation on dielectric constant ( ɛ'), dielectric loss tangent ( tan δ) and AC resistivity ( ρAC) was carried out in the applied field frequency range 100 Hz- 1 MHz, at room temperature. Dielectric constant and loss tangent were found to decrease as the frequency increases. This is attributed to the Maxwell-Wagner polarization. Temperature-dependent DC resistivity was carried out in the temperature range from 300 to 800 K. From the compositional study, it was found that the dielectric constant shows decreasing trend with increasing both zinc concentration as well as doping percentage of lithium chloride. Conduction mechanism in these ferrites is discussed on the basis of electron exchange between Fe 2+ and Fe 3+ ions on the octahedral B-sites.

  7. 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.

  8. 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.

  9. Electrolyte additive to improve performance of MCMB/LiNi 1/3Co 1/3Mn 1/3O 2 Li-ion cell

    NASA Astrophysics Data System (ADS)

    Qin, Yan; Chen, Zonghai; Lu, Wenquan; Amine, Khalil

    The electrolyte additive, 3,9-divinyl-2,4,8,10-tetraoxaspiro[5,5] undecane (TOS), was investigated as a means to improve the life of mesocarbon microbead (MCMB)/Li 1.1[Ni 1/3Co 1/3Mn 1/3] 0.9O 2 (NCM) cells for high-power applications. With the addition of an appropriate amount of TOS (no more than 1 wt%) to MCMB/NCM cells, the capacity retention was significantly improved at 55 °C compared with cells containing pristine electrolyte. Aging tests at 55 °C indicated that the capacity retention of the negative electrode had benefited as a result of the formation of a stable passivation film at the surface of the carbon electrode due to TOS reduction. Electrochemical impedance spectroscopy showed that a TOS addition of more than 0.5 wt% increased the cell interfacial impedance. Differential scanning calorimetry showed that the thermal stability of lithiated MCMB was also improved with the TOS addition.

  10. 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}.

  11. 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.

  12. 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).

  13. Electrochemical properties of magnesium doped LiFePO{sub 4} cathode material prepared by sol–gel method

    SciTech Connect

    Zhao, Xiaohui; Baek, Dong-Ho; Manuel, James; Heo, Min-Yeong; Yang, Rong; Ha, Jong Keun; Ryu, Ho-Suk; Ahn, Hyo-Jun; Kim, Ki-Won; Cho, Kwon-Koo; Ahn, Jou-Hyeon

    2012-10-15

    Magnesium doped Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C (x = 0.00, 0.01, 0.03, 0.05) cathode materials were synthesized by sol–gel method, and the effect of magnesium doping as well as its content on the electrochemical properties for lithium batteries was also investigated{sub .} Their morphology was studied with field emission scanning electron microscope and Li{sub 1−2x}Mg{sub x}FePO{sub 4} materials showed the olivine phase without impurities. The thin carbon layer of Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C was confirmed by high resolution transmission electron microscopy. The magnesium doped Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C particles were smaller than those undoped. The Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C materials showed better cycling behavior than undoped LiFePO{sub 4}, especially at high C-rate in which Li{sub 0.94}Mg{sub 0.03}FePO{sub 4}/C composition exhibited the best electrochemical properties.

  14. Enhanced Electrochemical Stability of Quasi-Solid-State Electrolyte Containing SiO2 Nanoparticles for Li-O2 Battery Applications.

    PubMed

    Kim, Hyunjin; Kim, Tae Young; Roev, Victor; Lee, Heung Chan; Kwon, Hyuk Jae; Lee, Hyunpyo; Kwon, Soonchul; Im, Dongmin

    2016-01-20

    A stable electrolyte is required for use in the open-packing environment of a Li-O2 battery system. Herein, a gelled quasi-solid-state electrolyte containing SiO2 nanoparticles was designed, in order to obtain a solidified electrolyte with a high discharge capacity and long cyclability. We successfully fabricated an organic-inorganic hybrid matrix with a gelled structure, which exhibited high ionic conductivity, thereby enhancing the discharge capacity of the Li-O2 battery. In particular, the improved electrochemical stability of the gelled cathode led to long-term cyclability. The organic-inorganic hybrid matrix with the gelled structure played a beneficial role in improving the ionic conductivity and long-term cyclability and diminished electrolyte evaporation. The experimental and theoretical findings both suggest that the preferential binding between amorphous SiO2 and polyethylene glycol dimethyl ether (PEGDME) solvent led to the formation of the solidified gelled electrolyte and improved electrochemical stability during cycling, while enhancing the stability of the quasi-solid state Li-O2 battery. PMID:26698560

  15. 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

    2016-03-30

    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. PMID:26942895

  16. An Artificial SEI Enables the Use of A LiNi0.5Mn1.5O4 5 V Cathode with Conventional Electrolytes

    SciTech Connect

    Li, Juchuan ORNL; Baggetto, Loic ORNL; Martha, Surendra K ORNL; Veith, Gabriel M ORNL; Nanda, Jagjit ORNL; Liang, Chengdu ORNL; Dudney, Nancy J ORNL

    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.

  17. Anomalous thermopower in bismuth doped La-Li-Mn-O manganite

    NASA Astrophysics Data System (ADS)

    Kalyana Lakshmi, Yanapu; Gunadhor Singh, Okram; Venugopal Reddy, Paduru

    2015-01-01

    Two polycrystalline samples, La5/6Li1/6MnO3 and La2/3Bi1/6Li1/6MnO3 having the same Mn3+/Mn4+ ratio were synthesized by the wet chemical method. After characterizing the samples by X-ray powder diffraction studies, dc magnetization, electrical resistivity and thermopower measurements were also carried out. It has been found that bismuth doped sample exhibits huge thermopower of 0.9 V/K in the low temperature region. The observed anomalous behavior is explained on the basis of the coexistence of antiferromagnetic phase in ferromagnetic matrix. The huge thermopower exhibited by these samples might find applications in thermoelectric devices.

  18. Luminescence of defects in Li-doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Potek, Z.; Bryknar, Z.; Ptáek, P.; Hubika, Z.

    2005-01-01

    Photoluminescence of pure ZnO and ZnO:Li thin films prepared in the plasmachemical reactor with the hollow cathode can be observed after annealing of samples in the hydrogen atmosphere at temperatures within the range 300-600 °C. Photoluminescence was excited by light with the photon energy higher than 3.1 eV. Considering the differences between photoluminescence emission spectra of pure and doped ZnO thin films investigated in the spectral region (260-1000 nm) at temperature 12 K, it was concluded (i) photoluminescence emission from the region 3.10-1.77 eV is originated from the intrinsic centers of pure ZnO and (ii) the emission near 1.68 eV is associated with a transition from a state at bottom of the conduction band to a hole trapped in a localized state introduced by Li.

  19. Dielectric anomaly in Li-doped zinc oxide thin films grown by sol gel route

    NASA Astrophysics Data System (ADS)

    Dhananjay; Singh, Satyendra; Nagaraju, J.; Krupanidhi, S. B.

    2007-08-01

    Sol gel route was employed to grow polycrystalline thin films of Li-doped ZnO thin films (Zn1-xLixO, x=0.15). Polycrystalline films were obtained at a growth temperature of 400 500 °C. Ferroelectricity in Zn0.85Li0.15O was verified by examining the temperature variation of the real and imaginary parts of dielectric constant, and from the C V measurements. The phase transition temperature was found to be 330 K. The room-temperature dielectric constant and dissipation factor were 15.5 and 0.09 respectively, at a frequency of 100 kHz. The films exhibited well-defined hysteresis loop, and the values of spontaneous polarization (Ps) and coercive field were 0.15 μC/cm2 and 20 kV/cm, respectively, confirming the presence of ferroelectricity.

  20. 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

  1. Investigations on spectroscopic properties of Er(3+)-doped Li-Zn fluoroborate glass.

    PubMed

    Thomas, Sunil; Sajna, M S; George, Rani; Rasool, Sk Nayab; Joseph, Cyriac; Unnikrishnan, N V

    2015-09-01

    Er(3+)-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 Er(3+)-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 (4)I13/2↔(4)I15/2 transitions. The results of the present glass were compared with those obtained for some other Er(3+)-doped glass systems. PMID:25863458

  2. 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.

  3. A search for a strong physisorption site for H2 in Li-doped porous carbons.

    PubMed

    Maresca, O; Pellenq, R J-M; Marinelli, F; Conard, J

    2004-12-22

    The mechanism of hydrogen absorption between two coronene molecules has been studied by first principle calculations. Examination of different sites for H(2) molecule confirmed the classical picture of physisorption. We have also considered molecular hydrogen adsorption in a charged carbon structure achieved by doping with lithium at a density corresponding to the intercalate compound LiC(6). We have performed different types of calculations [Hartree-Fock and density functional theory (DFT)] for various atomic basis sets using CRYSTAL98, GAUSSIAN98, and DMOL3 codes. B3LYP-DFT (B3LYP-three-parameter functional of Backe, Lee, Yang and Parr) energy minimization calculations unravel that there is a stable adsorption site for molecular hydrogen in Li-doped sp(2) carbon structure. These calculations also give an insight into the atomic configurations of interlayer species (H(2) and Li) as the interlayer spacing increases. It can be shown that large changes occur in the positions and electronic properties of interlayer species. Hydrogen molecule does not show any tendency for dissociation and adopts a position in the interlayer void that is deeply related to that of lithium ions. We have evidenced a rather large charge transfer from lithium and capping hydrogen species on neighboring slab carbon atoms that induce the stabilization of molecular hydrogen. We have also found that rotating one carbon layer with respect to the other one (at constant interlayer distance) does not change the adsorption energy to a large extent. The best adsorption site is about five times deeper than the physisorption site found in the undoped case and occurs at an interlayer separation of 5.5+/-0.5 A. The corresponding atomic configuration consists in a hydrogen molecule standing (nearly) perpendicular to the plane surface surrounded by the three lithium ions in a configuration close to that of the LiC(6) intercalation compound. PMID:15606276

  4. Directionally solidified Eu doped CaF2/Li3AlF6 eutectic scintillator for neutron detection

    NASA Astrophysics Data System (ADS)

    Kamada, Kei; Hishinuma, Kousuke; Kurosawa, Shunsuke; Shoji, Yasuhiro; Pejchal, Jan; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira

    2015-12-01

    Eu doped CaF2/Li3AlF6 eutectics were grown by μ-PD method. The directionally solidified eutectic with well-aligned 600 nm diameter Eu:CaF2 scintillator fibers surrounded with Li3AlF6 was prepared. The grown eutectics showed an emission peak at 422 nm ascribed to Eu2+ 4f-5d transition from Eu:CaF2 scintillation fiber. Li concentration in the Eu:CaF2-Li3AlF6 eutectic is around 0.038 mol/cm3,which is two times higher than that of LiCaAlF6 single crystal (0.016 mol/cm3). The light yield of Eu:CaF2-Li3AlF6 eutectic was around 7000 ph/neutron. The decay time was about 550 ns (89%) and 1450 ns (11%).

  5. Comments on the defect chemistry of magnesium-doped lithium niobate (LiNbO{sub 3})

    SciTech Connect

    Donnerberg, H.

    1996-05-01

    Congruently grown LiNbO{sub 3} is known to be highly defective due to its significant Li{sub 2}O deficiency. At present, two stoichiometry-related defect-chemical models are discusses which can be distinguished with respect to the occurrence of Li or Nb vacancies. The Nb-vacancy model takes advantage of ilmenite-structured LiNbO{sub 3} and predicts a niobium antisite concentration being at least five times as large as in the Li-vacancy model. In the present contribution, it is argued that the magnesium-doping mechanisms are essentially independent of these particular differences. It is argued that extended stoichiometry-related defect clusters represent a key for a proper understanding of the defect chemistry of impurity cations. The discussion is mainly based on recent shell-model simulations of perfect and defective LiNbO{sub 3}.

  6. 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.

  7. 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. PMID:26451678

  8. A high precision study of the electrolyte additives vinylene carbonate, vinyl ethylene carbonate and lithium bis(oxalate)borate in LiCoO2/graphite pouch cells

    NASA Astrophysics Data System (ADS)

    Wang, David Yaohui; Sinha, N. N.; Burns, J. C.; Petibon, R.; Dahn, J. R.

    2014-12-01

    The effects of three well-known electrolyte additives, used singly or in combination, on LiCoO2/graphite pouch cells has been investigated using the ultra high precision charger (UHPC) at Dalhousie University, electrochemical impedance spectroscopy (EIS) and long term cycling Vinylene carbonate (VC), vinyl ethylene carbonate (VEC), and lithium bis(oxalato) borate (LiBOB) were chosen for study. The results show that combinations of electrolyte additives that act synergistically can be more effective than a single electrolyte additive. However, simply using 2% VC yielded cells very competitive in coulombic efficiency (CE), charge endpoint capacity slippage and charge transfer resistance (Rct). For cells with 1% LiBOB and VC (1, 2, 4 or 6%), adding VC above 2% does not increase the CE, but increases the electrode charge transfer impedances. Rct for cells containing 1% LiBOB and VEC (0.5, 1 or 4%) decreased after long term cycling (1800 h), compared to that tested after the UHPC cycling (500 h) indicating that VEC might be useful for the design of power cells. However, the opposite behaviour (increasing Rct with cycle number) was observed for the control cells or cells containing LiBOB and/or VC.

  9. Ion conduction and relaxation in PEO-LiTFSI-Al{sub 2}O{sub 3} polymer nanocomposite electrolytes

    SciTech Connect

    Das, S.; Ghosh, A.

    2015-05-07

    Ion conduction and relaxation in PEO-LiTFSI-Al{sub 2}O{sub 3} polymer nanocomposite electrolytes have been studied for different concentrations of Al{sub 2}O{sub 3} nanoparticles. X-ray diffraction and differential scanning calorimetric studies show that the maximum amorphous phase of PEO is observed for PEO-LiTFSI embedded with 5 wt. % Al{sub 2}O{sub 3}. The maximum ionic conductivity ∼3.3 × 10{sup −4} S cm{sup −1} has been obtained for this composition. The transmission electron microscopic image shows a distribution of Al{sub 2}O{sub 3} nanoparticles in all compositions with size of <50 nm. The temperature dependence of the ionic conductivity follows Vogel-Tamman-Fulcher nature, indicating a strong coupling between ionic and polymer chain segmental motions. The scaling of the ac conductivity implies that relaxation dynamics follows a common mechanism for different temperatures and Al{sub 2}O{sub 3} concentrations. The imaginary modulus spectra are asymmetric and skewed toward the high frequency sides of the maxima and analyzed using Havriliak-Negami formalism. The temperature dependence of the relaxation time obtained from modulus spectra also exhibits Vogel-Tamman-Fulcher nature. The values of the stretched exponent obtained from Kohlrausch-Williams-Watts fit to the modulus data are fairly low, suggesting highly non-exponential relaxation for all concentrations of Al{sub 2}O{sub 3} in these electrolytes.

  10. Binary room-temperature complex electrolytes based on LiClO 4 and organic compounds with acylamino group and its characterization for electric double layer capacitors

    NASA Astrophysics Data System (ADS)

    Wu, Feng; Chen, Renjie; Wu, Fan; Li, Li; Xu, Bin; Chen, Shi; Wang, Guoqing

    Binary room-temperature complex electrolytes have been synthesized based on lithium perchlorate (LiClO 4) and organic molecules with acylamino groups, including acetamide, ethyleneurea, 2-oxazolidinone (OZO), urea, methylurea (NMU) and 1,3-dimethylurea (DMU). Both LiClO 4 and all organic molecules with acylamino groups are solid at room-temperature, but their mixtures at the proper molar ratio are liquid with a liquidus temperature about below 25 °C characterized by differential scanning calorimetry (DSC). Infrared spectroscopic studies show that the organic molecules can coordinate with the Li + cation and the ClO 4 - anion via their polar groups (the C dbnd O and NH groups). Such strong interactions lead to the dissociation of LiClO 4 and the breakage of the hydrogen bonds among the organic molecules, resulting in the formation of the complex systems. Electrochemical performances of the complex electrolytes are evaluated with ac impedance spectroscopy, cyclic voltammetry (CV), and in a test electric double layer capacitor (EDLC), respectively. The LiClO 4-acetamide electrolyte at molar ratio 1:5.5 exhibits the highest ionic conductivity, 1.25 × 10 -3 S cm -1 at 25 °C and 11.5 × 10 -3 S cm -1 at 80 °C. The analysis for the CV behavior indicates that the electrochemical stability window of these electrolytes is above 3 V. The results demonstrate that these complex systems are promising electrolyte candidates for supercapacitor and probably other electrochemical devices.

  11. Effective ionic charge polarization using typical supporting electrolyte and charge injection phenomena in molecularly doped polymer light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Itoh, Eiji; Yamashita, Takanori; Miyairi, Keiichi

    2002-11-01

    An effective method of enhancing charge injection and electroluminescence efficiency of polymer-based light-emitting diodes is introduced. Spin-coated films of poly (N-vinylcarbazole) blended with electron-transport material (Bu-PBD), laser dye (Coumarin6), and the typical supporting electrolyte [tetraethylammonium perchlorate (TEAP)] were examined and it was found that the injection current and luminance of the light emitting diodes doped with TEAP were enhanced dramatically after heat treatment at 80 degC and appropriate biasing in an external electric field of 1.5 x108 V/m at this temperature. A charge injection model based on Fowler-Nordheim tunneling is proposed, taking into account electric field distortion due to the accumulation of ionic space charges at the electrode/film interface. The relaxation time of ionic polarization is found to be related to the cation size of the electrolyte.

  12. Structural and spectroscopic properties of Li+ co-doped MgAl2O4: Eu3+ nanophosphors

    NASA Astrophysics Data System (ADS)

    Faizan, Mohd.; Ahmad, Shabbir

    2016-05-01

    The red light emitting highly-luminescent Li+ co-doped magnesium aluminates (MgAl2O4: Eu3+) nanophosphors were synthesized by combustion synthesis method. The phosphors were characterized by XRD, FTIR, UV-visible and photoluminescence (PL) spectroscopy. The crystal structure and phase of the phosphors were investigated using XRD. The band gap of pure, Eu3+ doped and Li+ codoped MgAl2O4 phosphor were obtained from the DR spectra using the K-M function F(R∞). The photoluminescence spectra of MgAl2O4:Eu3+ and Li+ codoped MgAl2O4:Eu3+ phosphors were described by well known 5D0-7Fj transitions (J=0, 1, 2, 3, 4). The emission intensity of MgAl2O4:Eu3+ phosphor is enhanced with Li+ codoping.

  13. Effect of sol-gel process parameters on the properties of a Li1.3Ti1.7Al0.3(PO4)3 solid electrolyte for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Lee, Seoung Soo; Lee, Jing; Jung, Yeon-Gil; Kim, Jae-Kwang; Kim, Youngsik

    2016-01-01

    In this study, the influence of the processing parameters, such as the synthesis temperature and the lithium sources on the structure, particle size, morphology and ionic conductivity of Li1+ x Ti2- x Al x (PO4)3 (LTAPO) was investigated. LiNO3, LiCl, and Li acetate were employed as lithium sources for investigating the effects of Li sources on the properties of the solid electrolyte. The morphologies and the particle size distribution of the prepared LTAPO samples were analyzed by using scanning electron microscopy (SEM) and a laser particle size analyzer. Their crystallinities were measured by means of X-ray diffraction (XRD). An increase in the synthesis temperature caused a pronounced growth in the particle size without any impurities, especially at temperatures above 700 °C. In addition, LiCl lithium sources showed the highest particles size. The effect of the processing parameters on the ionic conductivity of the prepared LTAPO was investigated by using electrochemical impedance spectroscopy (EIS). The ionic conductivities of the LTAPO prepared by using an optimized synthesis temperature with different lithium sources were 8.36 × 10-4, 5.73 × 10-4, and 7.18 × 10-4 S/cm for C-LTAPO, A-LTAPO, and N-LTAPO, respectively. The properties of the ceramic solid electrolyte were shown to be affected by the choice of the synthesis temperature and the Li source material.

  14. Lithium stoichiometry of solid electrolytes based on tetragonal Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12}

    SciTech Connect

    Il’ina, E.A.; Raskovalov, A.A.; Shevelin, P.Y.; Voronin, V.I.; Berger, I.F.; Zhyravlev, N.A.

    2014-05-01

    Graphical abstract: - Highlights: • We prepared Li{sub x}La{sub 3}Zr{sub 2}O{sub 8.5+0.5x} (x = 6, 7, 8, 9, 10) by the citrate–nitrate method. • We studied phase composition and conductivity of Li{sub x}La{sub 3}Zr{sub 2}O{sub 8.5+0.5x}. • We proposed a simple method to determine the carbonate impurity content in the solid electrolytes. • The synthesized solid electrolytes Li{sub x}La{sub 3}Zr{sub 2}O{sub 8.5+0.5x} (x = 7–9) have 1.32–3.49 wt.% Li{sub 2}CO{sub 3}. • The composition with x = 9 has high total conductivity, 7.5 × 10{sup −6} S cm{sup −1}, at room temperature. - Abstract: Samples of Li{sub x}La{sub 3}Zr{sub 2}O{sub 8.5+0.5x} (x = 6, 7, 8, 9, 10) were synthesized with the citrate–nitrate method. Neutron diffraction studies have shown the presence of lithium carbonate impurities in the synthesized compounds. We propose a simple and effective method to determine the carbonate impurity content in the solid electrolytes. The technique is based on the measurement of the carbon dioxide volume produced from the interaction of the investigated material with acid. Determined in this way, the content of Li{sub 2}CO{sub 3} in the synthesized electrolytes Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12}, Li{sub 8}La{sub 3}Zr{sub 2}O{sub 12.5} and Li{sub 9}La{sub 3}Zr{sub 2}O{sub 13} are 1.32 ± 0.04, 1.95 ± 0.06 and 3.49 ± 0.10 wt.%, respectively. From the obtained data, the actual lithium content per formula unit of complex oxide was calculated for the synthesized compounds. The composition with x = 9 had the highest total conductivity, σ = 7.5 × 10{sup −6} S cm{sup −1}, at room temperature. All the investigated electrolytes have an activation energy of approximately 50 kJ mol{sup −1}.

  15. 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}.

  16. Preparation and characterization of Eu-doped LiNbO3 films prepared by the sol-gel method

    NASA Astrophysics Data System (ADS)

    Takahashi, Makoto; Iyoda, Kazuki; Maeda, Yoshihiko; Miyauchi, Toshiyuki; Ohkido, Sadao; Sato, Shoji; Wakita, Koichi; Kajitani, Naofumi; Hotta, Kazutoshi; Kurachi, Masato

    2008-02-01

    Europium (Eu3+)-doped lithium niobate (LiNbO3) thick films were deposited on a z-cut congruent LiNbO3 (LN) substrate by the sol-gel method from 0.20moldm-3 precursor solution containing various Eu3+ concentrations and 0.10moldm-3 polyvinylalcohol, and their crystal characteristics were evaluated. The Eu3+ concentration in the LN film was controlled by the Eu3+ concentration in the starting solution. The orientation relationships between Eu3+-doped LN films and LN substrates were determined by x-ray diffraction and Raman spectroscopy, and (006) oriented Eu-doped LN epitaxial layers with parallel epitaxial relationships could be grown on the z-cut LN wafer. The refractive indices of Eu3+-doped LN films decreased with the increase of Eu3+ concentration. The luminescence intensities (D05→FJ7 emission) increased with increasing of the Eu3+ ion concentration.

  17. Passivation of Aluminum in Lithium-ion Battery Electrolytes withLiBOB

    SciTech Connect

    Zhang, Xueyuan; Devine, Thomas M.

    2006-09-09

    A combination of cyclic polarization tests, electrochemical impedance spectroscopy, and electrochemical quartz crystal microbalance (EQCM) measurements indicate a film is formed when aluminum is polarized above 4.5V in 1:1 EC+DMC with 1M LiBOB. The quantity of film that is formed increases with increasing applied potential. Results of EQCM tests suggest the film is AlBO{sub 3}. The film is very protective against corrosion and inhibits pitting corrosion of aluminum in normally corrosive 1M LiTFSI.

  18. Comparison of the TL fading characteristics of Ge-doped optical fibres and LiF dosimeters.

    PubMed

    Noor, Noramaliza M; Shukor, Nasiha A; Hussein, M; Nisbet, A; Bradley, D A

    2012-07-01

    Fading is important in choosing appropriate thermoluminescence (TL) materials for particular applications. Comparison is made herein of changes due to fading in the TL yield of Ge-doped fibres and lithium fluoride (LiF) dosimeters, for varying temperature and dose. The fading is independent of dose for all investigated dosimeters while the loss in TL yield reduces for lower storage temperatures. At room temperature and for 133 days of storage, a maximum signal loss of 5% has been observed for both forms of LiF dosimeter, while 9 and 50 μm core diameter Ge-doped fibres produced a loss of 11% and 8%, respectively. PMID:22134025

  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. Successes and failures of Hubbard-corrected density functional theory: The case of Mg doped LiCoO2

    NASA Astrophysics Data System (ADS)

    Santana, Juan A.; Kim, Jeongnim; Kent, P. R. C.; Reboredo, Fernando A.

    2014-10-01

    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 in 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.

  1. Successes and failures of Hubbard-corrected density functional theory: the case of Mg doped LiCoO2.

    PubMed

    Santana, Juan A; Kim, Jeongnim; Kent, P R C; Reboredo, Fernando A

    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 in 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. PMID:25362331

  2. Successes and failures of Hubbard-corrected density functional theory. The case of Mg doped LiCoO2

    DOE PAGESBeta

    Santana Palacio, Juan A.; Kim, Jeongnim; Kent, Paul R.; Reboredo, Fernando A.

    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

  3. Luminescence enhancement of ZnGa 2O 4:Mn 2+ by Ge 4+ and Li + doping

    NASA Astrophysics Data System (ADS)

    Kim, J. S.; Park, H. L.; Kim, G. C.; Kim, T. W.; Hwang, Y. H.; Kim, H. K.; Mho, S. I.; Han, S. D.

    2003-05-01

    Structural and optical properties of ZnGa 2O 4:Ge 4+ and ZnGa 2O 4:Ge 4+, Li +, Mn 2+ phosphors were investigated by using X-ray diffraction (XRD), photoluminescence (PL) and cathodoluminescence (CL) measurements. The XRD patterns show that Ge-doped ZnGa 2O 4 has a spinel phase and its lattice constant increases with respect to ZnGa 2O 4. Emission wavelength shifts from 400 to 360 nm in comparison with ZnGa 2O 4 when Ge is doped in ZnGa 2O 4 and a peak related with oxygen defect was observed in Ge-doped ZnGa 2O 4. The CL luminance of ZnGa 2O 4:Ge 4+, Li +, Mn 2+ phosphors is seven times brighter than that of ZnGa 2O 4:Mn 2+. This drastic luminance improvement can be attributed to Ge doping in ZnGa 2O 4 acting as donor ion and Li doping resulting in increasing conductivity of ZnGa 2O 4. These results indicate that ZnGa 2O 4:Ge 4+, Li +, Mn 2+ phosphors hold promise for potential applications in field-emission display devices with high brightness operating in green spectral regions.

  4. Improving the High-Voltage Li2FeMn3O8 Cathode by Chlorine Doping.

    PubMed

    Dai, Jiaqi; Zhou, Lihui; Han, Xiaogang; Carter, Marcus; Hu, Liangbing

    2016-05-01

    High-capacity and high-voltage cathode materials are desirable for high-energy-density lithium ion batteries. Among various cathode materials, Li2FeMn3O8 is attractive due to its high working voltage, low toxicity, and low cost. However, its superior electrochemical properties are significantly limited by the intrinsic defects in the Li2FeMn3O8 cathode, which makes the theoretical working voltage (4.9 V) and capacity (148 mAh/g) hard to reach. In this paper, we demonstrated that Cl doping can effectively increase the capacity and working voltage of the Li2FeMn3O8 cathode. X-ray photoelectron spectroscopy reveals that Cl doping reduced the valence state and increased the electron binding energy in cations and thus increased the voltage and enhanced the capacity of the Li2FeMn3O8 cathode. Our results also indicate that Cl doping can be a promising low-cost method to improve the electrochemical performance of various oxide cathode materials, including LiCoO2 and LiMn2O4. PMID:27046350

  5. 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.

  6. Low Temperature Synthesis of Cubic-phase Fast-ionic Conducting Bi-doped Garnet Solid State Electrolytes

    NASA Astrophysics Data System (ADS)

    Schwanz, Derek K.; Marinero, Ernesto

    We report on the synthesis of cubic-phase fast ionic conducting garnet solid state electrolytes based on LiLaZrO (LLZO) at unprecedented low synthesis temperatures. Ionic conductivities around 1.2 x 10-4 S/cm are readily achieved. Bismuth aliovalent substitution into LLZO utilizing the Pechini processing method is successfully employed to synthesize LiLaZrBiO compounds. Cubic phase LiLaZrBiO powders are generated in the temperature range 650C to 900C in air. In contrast, in the absence of Bi and under identical synthesis conditions, the cubic phase of LiLaZrO is not formed below 750C and a transformation to the poor ionically conducting tetragonal phase is observed at 800C for the undoped compound. The critical role of Bi in lowering the formation temperature of the garnet cubic phase and the improvements in ionic conductivity are elucidated in this work through microstructural and electrochemical studies.

  7. Effect of water on solid electrolyte interphase formation in Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Saito, M.; Fujita, M.; Aoki, Y.; Yoshikawa, M.; Yasuda, K.; Ishigami, R.; Nakata, Y.

    2016-03-01

    Time-of-flight-elastic recoil detection analysis (TOF-ERDA) with 20 MeV Cu ions has been applied to measure the depth profiles of solid electrolyte interphase (SEI) layers on the negative electrode of lithium ion batteries (LIB). In order to obtain quantitative depth profiles, the detector efficiency was first assessed, and the test highlighted a strong mass and energy dependence of the recoiled particles, especially H and He. Subsequently, we prepared LIB cells with different water contents in the electrolyte, and subjected them to different charge-discharge cycle tests. TOF-ERDA, X-ray photoelectron spectrometry (XPS), gas chromatography (GC), ion chromatography (IC), and 1H nuclear magnetic resonance (1H NMR) were applied to characterize the SEI region of the negative electrode. The results showed that the SEI layer is formed after 300 cycle tests, and a 500 ppm water concentration in the electrolyte does not appear to cause significant differences in the elemental and organic content of the SEI.

  8. 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.

  9. 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.

  10. In situ AFM imaging of Li-O2 electrochemical reaction on highly oriented pyrolytic graphite with ether-based electrolyte.

    PubMed

    Wen, Rui; Hong, Misun; Byon, Hye Ryung

    2013-07-24

    Understanding the lithium-oxygen (Li-O2) electrochemical reaction is of importance to improve reaction kinetics, efficiency, and mitigate parasitic reactions, which links to the strategy of enhanced Li-O2 battery performance. Many in situ and ex situ analyses have been reported to address chemical species of reduction intermediate and products, whereas details of the dynamic Li-O2 reaction have not as yet been fully unraveled. For this purpose, visual imaging can provide straightforward evidence, formation and decomposition of products, during the Li-O2 electrochemical reaction. Here, we present real-time and in situ views of the Li-O2 reaction using electrochemical atomic force microscopy (EC-AFM). Details of the reaction process can be observed at nano-/micrometer scale on a highly oriented pyrolytic graphite (HOPG) electrode with lithium ion-containing tetraglyme, representative of the carbon cathode and ether-based electrolyte extensively employed in the Li-O2 battery. Upon oxygen reduction reaction (ORR), rapid growth of nanoplates, having axial diameter of hundreds of nanometers, length of micrometers, and ~5 nm thickness, at a step edge of HOPG can be observed, which eventually forms a lithium peroxide (Li2O2) film. This Li2O2 film is decomposed during the oxygen evolution reaction (OER), for which the decomposition potential is related to a thickness. There is no evidence of byproduct analyzed by X-ray photoelectron spectroscopy (XPS) after first reduction and oxidation reaction. However, further cycles provide unintended products such as lithium carbonate (Li2CO3), lithium acetate, and fluorine-related species with irregular morphology due to the degradation of HOPG electrode, tetraglyme, and lithium salt. These observations provide the first visualization of Li-O2 reaction process and morphological information of Li2O2, which can allow one to build strategies to prepare the optimum conditions for the Li-O2 battery. PMID:23808397

  11. New Li-doped fullerene-intercalated phthalocyanine covalent organic frameworks designed for hydrogen storage.

    PubMed

    Guo, Jing-Hua; Zhang, Hong; Miyamoto, Yoshiyuki

    2013-06-01

    Applying density functional theory (DFT) calculations, we have designed fullerenes (C20, C24, C26, C28, C30, C36, C60 and C70) intercalated phthalocyanine covalent organic frameworks (Cn-Pc-PBBA COFs). First principles molecular dynamics (MD) simulations showed that the structures of Cn-Pc-PBBA COFs are stable at room temperature and even at higher temperature (500 K). The interlayer distance of Pc-PBBA COF has been expanded to 7.48-13.25 Å by the intercalated fullerenes, and the pore volume and surface area were enlarged by 2.3-3.1 and 2.0-2.6 times, respectively. The grand canonical Monte Carlo (GCMC) simulations show that our designed Cn-Pc-PBBA COFs exhibit a superior hydrogen storage capability: at 77 K and P = 100 bar, the hydrogen gravimetric and volumetric uptakes reach 9.4-12 wt% and 48.1-52.2 g L(-1), respectively. To meet the requirement for practical application in hydrogen storage, we use the Li-doping method to modify the hydrogen storage performance of Cn-Pc-PBBA COFs. Our results show that the Li atoms can stably locate on the surface of C30-, C36, C60 and C70-Pc-PBBA COFs. At T = 298 K and P = 100 bar, for these four Li-doped Cn-Pc-PBBA COFs, the gravimetric and volumetric uptakes of H2 reach 4.2 wt% and 18.2 g L(-1), respectively. PMID:23609981

  12. 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.

  13. Electrochemical reactions and cathode properties of Fe-doped Li2O for the hermetically sealed lithium peroxide battery

    NASA Astrophysics Data System (ADS)

    Harada, Kosuke; Hibino, Mitsuhiro; Kobayashi, Hiroaki; Ogasawara, Yoshiyuki; Okuoka, Shin-ichi; Yonehara, Koji; Ono, Hironobu; Sumida, Yasutaka; Yamaguchi, Kazuya; Kudo, Tetsuichi; Mizuno, Noritaka

    2016-08-01

    Fe-doped Li2O (FDL) is synthesized mechanochemically and is demonstrated as a new Co-free cathode material for use in sealed Li2O2 batteries, which have been proposed as high energy density batteries. Fe3+ ions are substitutionally doped into the Li sites in an antifluorite-type Li2O structure to create FDL. The FDL consists of (Li0.82Fe0.06)2O (d-FDL) and high-temperature form of Li5FeO4 (o-FDL), in which Fe3+ ions disorderly and orderly arranged, respectively. According to the Mössbauer spectra and quantitative peroxide species analysis, the FDL cathode operates principally based on the redox reaction between O22- and O2-. X-ray diffraction study reveals that the reversible formation of O22- proceeds mainly in the d-FDL. An irreversible side reaction involving the evolution of oxygen gas occurs when the cathode is charged to more than 250 mAh g-1. The FDL (Fe/(Li + Fe) = 10 at%) cathode exhibits a reversible capacity of 200 mAh g-1 over 200 cycles at a current density of 22.5 mA g-1.

  14. 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. PMID:26353479

  15. Control of p- and n-type conductivities in Li-doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Lu, J. G.; Zhang, Y. Z.; Ye, Z. Z.; Zeng, Y. J.; He, H. P.; Zhu, L. P.; Huang, J. Y.; Wang, L.; Yuan, J.; Zhao, B. H.; Li, X. H.

    2006-09-01

    Li-doped ZnO films were prepared by pulsed laser deposition. The carrier type could be controlled by adjusting the growth conditions. In an ionized oxygen atmosphere, p-type ZnO was achieved, with the hole concentration of 6.04×1017cm-3 at an optimal Li content of 0.6at.%, whereas ZnO exhibited n-type conductivity in a conventional O2 growth atmosphere. At a Li content of more than 1.2at.% only high-resistivity ZnO was obtained. The amount of Li introduced into ZnO and the relative concentrations of such defects as Li substitutions and interstitials could play an important role in determining the conductivity of films.

  16. 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. PMID:25138922

  17. 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.

  18. 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.

  19. Fabrication of ultrathin solid electrolyte membranes of β-Li3PS4 nanoflakes by evaporation-induced self-assembly for all-solid-state batteries

    DOE PAGESBeta

    Wang, Hui; Hood, Zachary D.; Xia, Younan; Liang, Chengdu

    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

  20. Nb doped TiO2 as a Cathode Catalyst Support Material for Polymer Electrolyte Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    O'Toole, Alexander W.

    In order to reduce the emissions of greenhouse gases and reduce dependence on the use of fossil fuels, it is necessary to pursue alternative sources of energy. Transportation is a major contributor to the emission of greenhouse gases due to the use of fossil fuels in the internal combustion engine. To reduce emission of these pollutants into the atmosphere, research is needed to produce alternative solutions for vehicle transportation. Low temperature polymer electrolyte membrane fuel cells are energy conversion devices that provide an alternative to the internal combustion engine, however, they still have obstacles to overcome to achieve large scale implementation. T he following work presents original research with regards to the development of Nb doped TiO2 as a cathode catalyst support material for low temperature polymer electrolyte membrane fuel cells. The development of a new process to synthesize nanoparticles of Nb doped TiO2 with controlled compositions is presented as well as methods to scale up the process and optimize the synthesis for the aforementioned application. In addition to this, comparison of both electrochemical activity and durability with current state of the art Pt on high surface area carbon black (Vulcan XC-72) is investigated. Effects of the strong metal-support interaction on the electrochemical behavior of these materials is also observed and discussed.

  1. A perspective on coatings to stabilize high-voltage cathodes: LiMn1.5Ni0.5O4 with subnanometer Lipon cycled with LiPF6 electrolyte

    SciTech Connect

    Kim, Yoongu; Dudney, Nancy J; Chi, Miaofang; Martha, Surendra K; Nanda, Jagjit; Veith, Gabriel M; Liang, Chengdu

    2013-01-01

    High voltage Li-ion cathodes push the limits of stability for both cathode and electrolyte. Here subnanometer coatings of an amorphous thin film electrolyte (Lipon) improved the room temperature and 60 C cycling stability of a LiMn1.5Ni0.5O4 spinel cathode when charged to 4.9V with a standard LiPF6 carbonate electrolyte. The cathodes delivered superior C-rate performances up to a 5C discharge, when compared to the uncoated cathodes. Enhanced performance extended for at least 100 cycles. Electrochemical impedance spectroscopy indicates that Lipon slows the increase of interface resistance. Thicker 1-3nm Lipon coatings are sufficiently insulating as to block electronic transport to the cathode particles. Thick coatings also slow Mn dissolution. Results suggest that Lipon may act to scavenge impurities or block active sites that promote electrolyte decomposition. While greatly improved by the Lipon coating, this cathode is not sufficiently stable for long cycle life applications. Further work is needed to assess if and what surface coatings will ultimately stabilize the high voltage cathodes. Comments include insight from other studies of Lipon coated cathodes and directions for future research.

  2. 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.

  3. Size dependent electron-phonon coupling in N, Li, In, Ga, F and Ag doped ZnO thin films.

    PubMed

    Shinde, S S; Bhosale, C H; Rajpure, K Y

    2012-12-01

    Polarized micro-Raman measurements are performed to study the phonon modes of N, Li, In, Ga, F and Ag doped ZnO thin films, grown by spray pyrolysis on corning glass substrates. The E(2)(high) mode displays a visible asymmetric line shape. The size and dopant dependence onto coupling strength between electron and LO phonon is experimentally estimated. PMID:23010630

  4. Electrochemical performance of gadolinia-doped ceria (CGO) electrolyte thin films for ITSOFC deposited by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Reolon, Raquel Pereira; Halmenschlager, Cibele Melo; Neagu, Roberto; de Fraga Malfatti, Célia; Bergmann, Carlos Pérez

    2014-09-01

    Solid Oxide Fuel Cell is an attractive, efficient, alternative source of power generation. However several challenges remained for this technology to be viable. These challenges include high power density, degradation rate, and cost. One way to decrease the SOFC cost is to use stainless steel interconnector. To be able to use a stainless steel interconnector one of the challenges is to find a way to produce an electrolyte, which does not need sintering at high temperature. This work presents the results of the process applied to gadolinia-doped ceria thin films deposited in cycles by spray pyrolysis. The aim of this work was to obtain thin, dense, and continuous CGO coatings, which has electrochemical performance suitable to be used as electrolyte for SOFC. The results obtained show that the air flow rate influenced the droplets size and hence the film quality. X-ray diffraction analysis showed that the films were crystalline after the deposition. Electrochemical tests showed maximum power density of 510 mW cm-2 at 650 °C with a thickness average of 3.30 μm when the film was deposited in 12 cycles showing that the film has a potential to be used as an electrolyte for ITSOFC on metal support.

  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. 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.

  7. Growth and EPR and optical properties of Li 2B 4O 7 single crystals doped with Co 2+ ions

    NASA Astrophysics Data System (ADS)

    Piwowarska, D.; Kaczmarek, S. M.; Berkowski, M.; Stefaniuk, I.

    2006-05-01

    Li 2B 4O 7 single crystals doped with Co ions were grown by the Czochralski method. The electron paramagnetic resonance (EPR) and optical absorption spectra of Li 2B 4O 7 (LBO) single crystals doped with Co 2+ ions were measured. The EPR spectra could be described by the spin-Hamiltonian with an effective spin of S={1}/{2} in octahedral symmetry. The values of g and A tensors and direction cosines characterizing Co 2+ centers in the LBO crystal were determined for the first time also. The EPR data reveals at least two types of Co 2+ centers. Optical absorption was measured in the range of 200 to 3200 nm for "as-grown" and γ-irradiated samples of Co:Li 2B 4O 7 crystals confirming octahedral coordination of Co 2+ ions and cation vacancies arising in the "as-grown" crystal.

  8. Effect of hot pressing temperature on the electrochemical stability of Li2S-P2S5 (75 -- 25 % mole) as a solid electrolyte

    NASA Astrophysics Data System (ADS)

    Garcia Mendez, Maria Regina

    Solid state batteries can contribute to a more sustainable energy future providing the energy required when needed. It can facilitate the integration of renewable energy into the electrical grid and can provide the energy density required to make electric vehicles a massive technology without greenhouse emissions in operating conditions. To concretize the latter, high-performance electrolytes are necessary. Li2S-P2S5 (75-25% mole) is a promising solid-electrolyte that could potentially be used for this purpose. Its most appealing features include: high ionic conductivity at room temperature (~10-3 S/cm), low-temperature processing conditions, and low cost. Most likely, Li2S-P 2S5 (75-25% mole) would be integrated in a battery system using Li metal as an anode. Therefore, its stability against metallic lithium must be understood. The purpose of this work is to characterize the effect of Li2S-P2S5 (75-25% mole) processing conditions, most specifically hot pressing, and their effect on Li stability. It was found that improvements on electrochemical performance can be attained by promoting particle chemistry during hot pressing.

  9. 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.

  10. Raman imaging for LiCoO2 composite positive electrodes in all-solid-state lithium batteries using Li2S-P2S5 solid electrolytes

    NASA Astrophysics Data System (ADS)

    Otoyama, Misae; Ito, Yusuke; Hayashi, Akitoshi; Tatsumisago, Masahiro

    2016-01-01

    A composite positive electrode in an all-solid-state battery is prepared by mixing LiCoO2 particles and Li2S-P2S5 solid electrolytes. Raman spectroscopy is conducted for the composite positive electrodes before and after the initial charging process. Raman spectral changes are observed, which corresponds to structural changes of LiCoO2 particles during the charge test. However, some spectra indicate that several LiCoO2 particles show no structural changes although the cell is fully charged. A local state-of-charge (SOC) distribution map of the composite electrode is obtained by Raman mapping. The mapping image after the charge test shows that distributions of reactions exist in the composite positive electrode.

  11. Simplified gain calculation in erbium-doped LiNbO 3 waveguides

    NASA Astrophysics Data System (ADS)

    Kapoor, Amita; Jain, Geetika; Sharma, Enakshi K.

    2007-02-01

    The combination of excellent electro-optical, acousto-optical and non-linear optical properties makes lithium niobate (LiNbO 3) an attractive host material for integrated optical components such as electro-optical modulators, acousto-optically tunable wavelength filters and Bragg gratings. In the last few years Erbium doped LiNbO 3 waveguide optical amplifiers (EDWA's) have attracted increasing interest. The combination of the amplifying properties of erbium with the excellent acousto-optical and electro-optical properties of the waveguide substrate LiNbO 3 allows the development of a whole class of new waveguide devices of higher functionality. The optical gain achievable in Ti:Er:LiNbO 3 waveguides by optical pumping could compensate or even over compensate these scattering, absorption and insertion losses leading to "zero loss" devices with net optical gain. The different types of lasers and amplifiers can be combined with other active and passive devices on the same substrate to form integrated optical circuits (IOC's) for a variety of applications in optical communications, sensing, signal processing and measurement techniques. The analysis of Er-doped diffused channel waveguides is, hence, required for design of amplifying integrated optical circuits in order to optimize the performance of these gain devices. The coupled differential equations, which govern the evolution of, pump power (1484nm), signal power (1485 to 1600nm) and amplified spontaneous emission, involve integrals which depend explicitly on the modal fields at the pump and signal wavelength in the diffused channel waveguide. In general, it is not possible to obtain analytical forms for the modal fields and propagation constant, hence, to obtain them various approximate or numerical methods (BPM, finite difference or finite element) are used. In this paper the modal field profiles obtained by the variational analysis are further approximated to an appropriately chosen Gaussian function, which

  12. High pressure study of Li-doped fullerides, Li(x)C60 (x = 4,12), by x-ray diffraction and Raman spectroscopy.

    PubMed

    Pischedda, V; Yao, M; Debord, R; Gabarino, G; San-Miguel, A

    2014-09-10

    In this article we study the alkali metal-intercalated 2D polymeric Li4C60 and the monomeric Li12C60 under pressure up to 40 GPa at room temperature, using x-ray diffraction and Raman spectroscopy. Li4C60 undergoes several transitions in the studied pressure range. At pressures lower than 8 GPa, we observed changes in both diffraction patterns and Raman scattering spectra, probably due to the displacement of Li atoms. At 8 GPa another structural and electronic transition occurs. We observe an enhancement of background and a broadening of diffraction peaks. Raman modes weaken and broaden considerably. An important structural transition occurs at around 16 GPa, in which new Raman bands exhibit features similar to those of a reported 3D C60 polymeric structure. The XRD data shows a collapse in volume with the simultaneous formation of amorphous material. The cell parameters deviate from their early pressure evolution and become less compressible. The high pressure study of highly doped monomeric Li12C60 shows that its structural integrity is retained up to 13 GPa, with increasing pressure-induced structural distortion and disorder. Above 13 GPa, Li12C60 transforms to a highly disordered state. PMID:25134418

  13. 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

  14. Enhanced rate performance of LiFePO4/C by co-doping titanium and vanadium

    NASA Astrophysics Data System (ADS)

    Long, Yun-Fei; Su, Jing; Cui, Xiao-Ru; Lv, Xiao-Yan; Wen, Yan-Xuan

    2015-10-01

    V and Ti co-doped LiFePO4/C composites were synthesized by a wet milling assisted carbothermal reduction technology. The structure, morphology and electrochemical performance of the samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), magnetic susceptibility, positron annihilation lifetime spectra (PAS), scanning electron microscope (SEM), charge/discharge tests, electrochemical impedance spectroscopy (EIS) and cyclic voltammograms (CV). The results showed that the V and Ti co-doped samples kept the olivine structure of LiFePO4, but the synergistic effects between V3+ and Ti4+ in the lattice can increase the disorder degree of the lattice and create Li+ vacancies in LiFePO4/C, thus improve electronic conductivity and Li+ diffusion coefficient. LiV0.069Ti0.025Fe0.905PO4/C delivers an initial discharge capacity of 144.1 mAh g-1 with a capacity retention ratio of 99.4%, 96.3% and 93.6% after 100, 200 and 300 cycles at 10C, respectively. Remarkably, it still gives a high discharge capacity of 124.8 mAh g-1 even at a high rate of 20C.

  15. Interface Properties between Lithium Metal and a Composite Polymer Electrolyte of PEO18Li(CF3SO2)2N-Tetraethylene Glycol Dimethyl Ether

    PubMed Central

    Wang, Hui; Matsui, Masaki; Takeda, Yasuo; Yamamoto, Osamu; Im, Dongmin; Lee, Dongjoon; Imanishi, Nobuyuki

    2013-01-01

    The electrochemical properties of a composite solid polymer electrolyte, consisting of poly(ethylene oxide) (PEO)-lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and tetraethylene glycol dimethyl ether (TEGDME) was examined as a protective layer between lithium metal and a water-stable lithium ion-conducting glass ceramic of Li1+x+y(Ti,Ge)2−xAlxP3−ySiyO12 (LTAP). The lithium ion conductivity and salt diffusion coefficient of PEO18LiTFSI were dramatically enhanced by the addition of TEGDME. The water-stable lithium electrode with PEO18LiTFSI-2TEGDME, as the protective layer, exhibited a low and stable electrode resistance of 85 Ω·cm2 at 60 °C, after 28 days, and low overpotentials of 0.3 V for lithium plating and 0.4 V for lithium stripping at 4.0 mA·cm−2 and 60 °C. A Li/PEO18LiTFSI-2TEGDME/LTAP/saturated LiCl aqueous solution/Pt, air cell showed excellent cyclability up to 100 cycles at 2.0 mAh·cm−2. PMID:24957059

  16. Properties of Li-Doped NiO Thin Films Prepared by RF-Magnetron Sputtering.

    PubMed

    Kwon, Ho-Beom; Han, Joo-Hwan; Lee, Hee Young; Lee, Jai-Yeoul

    2016-02-01

    Li-doped NiO thin films were deposited on glass and c-axis (0001) sapphire single crystal substrates by radio frequency (RF)-niagnetron sputtering. The effects of the type of substrate, substrate temperature and atmosphere on the structural, electrical and optical properties of the NiO thin films were examined. The electrical conductivity of the NiO thin films depends on the type of substrate, substrate temperature and oxygen atmosphere. The electrical conductivity of the thin films on the glass and sapphire substrates was improved by the introduction of oxygen and decreased with increasing substrate temperature. The optical transmittance decreased with the introduction of oxygen and increased with increasing substrate temperature. PMID:27433612

  17. Nonvolatile photorefractive properties in triply doped stoichiometric Mg:Fe:Mn:LiTaO3 crystals

    NASA Astrophysics Data System (ADS)

    Sun, Ting; Zhang, Xiao-Dong; Sun, Liang; Wang, Rui

    2014-01-01

    We have grown triply doped Mg:Fe:Mn:LiTaO3 crystals with near stoichiometry using the top seeded solution growth technique. The defect structure was investigated by infrared absorption spectra and Curie temperature. Using a blue laser as the source, excellent photorefractive properties were obtained. Nonvolatile holographic storage properties were investigated using the dual wavelength technique. We got a very high fixed diffraction efficiency and nonvolatile holographic storage sensitivity. The blue light has more than enough energy to excite holes of deep (Mn) and shallow (Fe) trap centers with the same phase, which enhance dramatically the blue photorefractive properties and the nonvolatile holographic storage. Mg2+ ion is no longer damage resistant at blue laser, but enhances photorefractive characteristics.

  18. 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.

  19. Resolving the grain boundary and lattice impedance of hot-pressed Li7La3Zr2O12 garnet electrolytes

    DOE PAGESBeta

    Tenhaeff, Wyatt E.; Wang, Yangyang; Sokolov, Alexei P.; Wolfenstine, Jeff; Sakamoto, Jeffrey; Dudney, Nancy J.; Rangasamy, Ezhiyl

    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.

  20. Laser active F-aggregate colour centres in LiF monocrystals doped by divalent impurity cations

    NASA Astrophysics Data System (ADS)

    Khulugurov, V. M.; Salomatov, V. N.; Vassilikou-Dova, A.; Baryshnikov, V. I.; Kalogeras, I. M.; Grigorakakis, S.; Makarov, S. K.; Mikhalenko, A. A.

    1999-09-01

    F-aggregate colour centres in LiF crystals with divalent impurities (M = Ni, Co, Be, Mg) are investigated by optical and thermally stimulated depolarization current (TSDC) spectroscopy methods. The F+2 centres accumulation in the LiF:M2+ crystals is similar to the F+2 centres accumulation in undoped LiF. Accumulation of F+2-like colour centres was observed only in the LiF:Mg2+ crystals at the first stage of low temperature irradiation with radiation doses exceeding 107 R. F+2-like centres are not formed in LiF with Ni, Be and Co impurity ions. The difference between the properties of the magnesium on one hand and the nickel, beryllium or cobalt doped crystals on the other is discussed in terms of the Hayes-Nickols mechanism with extra anion vacancy generation in the case of the LiF:Mg2+ crystal. The absence of the mechanism in LiF:Ni2+ and LiF:Be2+ is connected to the reduction of the impurity Ni2+ and Be2+ ion valence state and in LiF:Co2+ to the small concentration of single Co2+V-c dipoles as a result of extensive dipole aggregation. The destruction of the F+2 and F+2-like centres takes place in LiF:Mg2+ crystals at the second stage of aggregation, at which other F-aggregated centres are formed, with the impurity-vacancy (IV) dipoles included in their composition. The two-band structure of the TSDC curve of irradiated LiF:Mg2+, with relaxation parameters close to those of single IV dipole reorientation bands, is in accordance with the above mechanism of aggregation. The creation mechanisms and models of laser active colour centres (F+2-like and F3Mg2+V-c `red' colour centres) are discussed.

  1. Electrolytically exfoliated graphene-loaded flame-made Ni-doped SnO2 composite film for acetone sensing.

    PubMed

    Singkammo, Suparat; Wisitsoraat, Anurat; Sriprachuabwong, Chakrit; Tuantranont, Adisorn; Phanichphant, Sukon; Liewhiran, Chaikarn

    2015-02-11

    In this work, flame-spray-made SnO2 nanoparticles are systematically studied by doping with 0.1-2 wt % nickel (Ni) and loading with 0.1-5 wt % electrolytically exfoliated graphene for acetone-sensing applications. The sensing films (∼12-18 μm in thickness) were prepared by a spin-coating technique on Au/Al2O3 substrates and evaluated for acetone-sensing performances at operating temperatures ranging from 150 to 350 °C in dry air. Characterizations by X-ray diffraction, transmission/scanning electron microscopy, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy and Raman spectroscopy demonstrated that Ni-doped SnO2 nanostructures had a spheriodal morphology with a polycrystalline tetragonal SnO2 phase, and Ni was confirmed to form a solid solution with SnO2 lattice while graphene in the sensing film after annealing and testing still retained its high-quality nonoxidized form. Gas-sensing results showed that SnO2 sensing film with 0.1 wt % Ni-doping concentration exhibited an optimal response of 54.2 and a short response time of ∼13 s toward 200 ppm acetone at an optimal operating temperature of 350 °C. The additional loading of graphene at 5 wt % into 0.1 wt % Ni-doped SnO2 led to a drastic response enhancement to 169.7 with a very short response time of ∼5.4 s at 200 ppm acetone and 350 °C. The superior gas sensing performances of Ni-doped SnO2 nanoparticles loaded with graphene may be attributed to the large specific surface area of the composite structure, specifically the high interaction rate between acetone vapor and graphene-Ni-doped SnO2 nanoparticles interfaces and high electronic conductivity of graphene. Therefore, the 5 wt % graphene loaded 0.1 wt % Ni-doped SnO2 sensor is a promising candidate for fast, sensitive and selective detection of acetone. PMID:25602118

  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. 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.

  4. CO oxidation over gold supported on Cs, Li and Ti-doped cryptomelane materials.

    PubMed

    Carabineiro, Sónia A C; Santos, Vera P; Pereira, M Fernando R; Órfão, José J M; Figueiredo, José L

    2016-10-15

    Cryptomelane-type manganese oxides were synthesized by redox reaction under acid and reflux conditions. Different metals (cesium, lithium and titanium) were incorporated into the tunnel structure by the ion-exchange technique. Gold was loaded onto these materials (1wt%) by a double impregnation method. The obtained catalysts were characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectrometry, scanning electron microscopy, X-ray diffraction and temperature-programmed reduction. The catalytic activity of these materials was evaluated in the oxidation of carbon monoxide. The incorporation of Cs, Li or Ti into cryptomelane was detrimental in terms of catalytic activity. Further addition of gold to cryptomelane doped materials significantly improved the catalytic performance, especially for Cs-K-OMS-2 and Li-K-OMS-2 (to a smaller extent). Addition of gold to the Ti containing material did not show a significant improvement. The observed trends are related to the effect of gold on samples reducibility and to the gold particle size. The lattice oxygen can also be considered accountable for the activity of the materials, since the most active cryptomelane catalysts are those with higher lattice oxygen donating ability for the oxidation of the CO molecule. PMID:27399615

  5. Lithium Ion Polymer Electrolyte Based on Pva-Pan

    NASA Astrophysics Data System (ADS)

    Genova, F. Kingslin Mary; Selvasekarapandian, S.; Rajeswari, N.; Devi, S. Siva; Karthikeyan, S.; Raja, C. Sanjeevi

    2013-07-01

    The polymer blend electrolytes based on polyvinylalcohol(PVA) and polyacrylonitrile (PAN) doped with lithium per chlorate (LiClO4) have been prepared by solution casting technique using DMF as solvent. The complex formation between blend polymer and the salt has been confirmed by Fourier transform infrared spectroscopy. The amorphous nature of the blend polymer electrolyte has been confirmed by X-ray diffraction analysis. The ionic conductivity of the prepared blend polymer electrolyte has been found by ac impedence spectroscopic analysis. The highest ionic conductivity has been found to be 5.0 X10-4 S cm -1 at room temperature for 92.5 PVA: 7.5PAN: 20 molecular wt. % of LiClO4. The effect of salt concentration on the conductivity of the blend polymer electrolyte has been discussed.

  6. Effect of Pr Additions to Li-doped Bi2212 Bulk Superconductors Sintered at Low Temperature

    NASA Astrophysics Data System (ADS)

    Miura, Akihiro; Oikawa, Dai; Andoh, Hiroya; Sugiura, Toko; Tsukamoto, Takehiko

    The physical properties study of the Bi2Sr2CaCu2Oy (Bi2212) ceramics samples sintered at low temperature has been carried out by measurement of electrical resistance and powder X-ray diffraction (XRD). The effects of Pr doping on the formation process of the Bi2212 phase, and its structural and superconducting features were studied. The samples were prepared by a solid-state reaction method from oxides and carbonate powders. The samples with nominal composition Bi2.12Sr1.90Ca1.02Cu1.96Li0.15Cl0.15Oy added with praseodymium oxide (Pr2O3) were sintered in air at 710 °C. The Pr2O3 addition ranging between 0.1mass% and 1.2mass% promotes the formation of the Bi2212 phase in low temperature synthesis. The full-width at half maximum (FWHM) value of the (200) and (0010) XRD peaks is slightly decreasing in the samples for low level doping and reaches a minimum around 0.6mass%. The maximum zero resistance temperature (Tc) is observed at 82.5K for the sample with 0.6mass% Pr2O3 addition by sintering even at 710 °C, which is about 150 °C lower than that of the non-added Bi2212 phase.

  7. Mitigation of the irreversible capacity and electrolyte decomposition in a LiNi 0.5Mn 1.5O 4/nano-TiO 2 Li-ion battery

    NASA Astrophysics Data System (ADS)

    Brutti, Sergio; Gentili, Valentina; Reale, Priscilla; Carbone, Lorenzo; Panero, Stefania

    Nanosized titanium oxides can achieve large reversible specific capacity (above 200 mAh g -1) and good rate capabilities, but suffer irreversible capacity losses in the first cycle. Moreover, due to the intrinsic safe operating potential (1.5 V), the use of titanium oxide requires to couple it with high-potential cathodes, such as lithium nickel manganese spinel (LNMO) in order to increase the energy density of the final cell. However the use of the 4.7 V vs. Li +/Li 0 LNMO cathode material requires to tackle the continuous electrolyte decomposition upon cycling. Coupling these two electrodes to make a lithium ion battery is thus highly appealing but also highly difficult because the cell balancing must account not only for the charge reversibly exchanged by each electrode but also for the irreversible charge losses. In this paper a LNMO-nano TiO 2 Li-ion cell with liquid electrolyte is presented: two innovative approaches on both the cathode and the anode sides were developed in order to mitigate the electrolyte decomposition upon cycling. In particular the LNMO surface was coated with ZnO in order to minimize the surface reactivity, and the TiO 2 nanoparticles where activated by incorporating nano-lithium in the electrode formulation to compensate for the irreversible capacity loss in the first cycle. With these strategies we were able to assemble balanced Li-ion coin cells thus avoiding the use of electrolyte additives and more hazardous and expensive ex-situ SEI preforming chemical or electrochemical procedures.

  8. White light emission from Dy3+-doped LiLuF4 single crystal grown by Bridgman method

    NASA Astrophysics Data System (ADS)

    Dong, Yan-ming; Xia, Hai-ping; Fu, Li; Li, Shan-shan; Gu, Xue-mei; Zhang, Jian-li; Wang, Dong-jie; Zhang, Yue-pin; Jiang, Hao-chuan; Chen, Bao-jiu

    2014-07-01

    Lithium lutetium fluoride (LiLuF4) single crystals doped with different Dy3+ ion concentrations were grown by Bridgman method. The Judd-Ofelt (J-O) strength parameters ( Ω 2, Ω 4, Ω 6) of Dy3+ in LiLuF4 crystal are calculated according to the measured absorption spectra and the J-O theory, by which the asymmetry of the Dy3+:LiLuF4 single crystal and the possibility of attaining stimulated emission from 4F9/2 level are analyzed. The capability of the Dy3+:LiLuF4 crystal in generating white light by simultaneous blue and yellow emissions under excitation with ultraviolet light is produced. The effects of excitation wavelength and doping concentration on chromaticity coordinates and photoluminescence intensity are also investigated. Favorable CIE coordinates, x=0.319 3 and y=0.349 3, can be obtained for Dy3+ ion in 2.701% molar doping concentration under excitation of 350 nm.

  9. 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.

  10. Green up-converted luminescence in (Er3+-Yb3+) co-doped LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Stoffel, M.; Rinnert, H.; Kokanyan, E.; Demirkhanyan, G.; Demirkhanyan, H.; Aillerie, M.

    2016-07-01

    Er3+ doped and (Er3+-Yb3+) co-doped LiNbO3 (LN) crystals grown by the Czochralski method are investigated by photoluminescence spectroscopy. Green up-converted luminescence is observed in Er3+ doped LN crystals under 980 nm excitation. This is explained by an energy transfer between two neighboring Er3+ ions. In (Er3+, Yb3+) co-doped LN crystals, the intensity of the green up-converted luminescence can be further enhanced suggesting that Yb3+ ions also contribute to the up-conversion process. Time resolved photoluminescence measurements clearly demonstrate that an efficient energy transfer occurs between Yb3+ and Er3+ ions. A theoretical model taking into account the contribution of both Er3+-Er3+ pairs and Yb3+-Er3+ pairs is able to describe correctly the decay of the up-converted luminescence.

  11. 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.

  12. 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.

  13. 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

  14. Fano resonance of Li-doped KTa1-xNbxO3 single crystals studied by Raman scattering.

    PubMed

    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

  15. Fano resonance of Li-doped KTa1‑xNbxO3 single crystals studied by Raman scattering

    NASA Astrophysics Data System (ADS)

    Rahaman, M. M.; Imai, T.; Sakamoto, T.; Tsukada, S.; Kojima, S.

    2016-04-01

    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.

  16. Transition metal redox and Mn disproportional reaction in LiMn0.5Fe0.5PO4 electrodes cycled with aqueous electrolyte

    NASA Astrophysics Data System (ADS)

    Zhuo, Zengqing; Hu, Jiangtao; Duan, Yandong; Yang, Wanli; Pan, Feng

    2016-07-01

    We performed soft x-ray absorption spectroscopy (sXAS) and a quantitative analysis of the transition metal redox in the LiMn0.5Fe0.5PO4 electrodes upon electrochemical cycling. In order to circumvent the complication of the surface reactions with organic electrolyte at high potential, the LiMn0.5Fe0.5PO4 electrodes are cycled with aqueous electrolyte. The analysis of the transitional metal L-edge spectra allows a quantitative determination of the redox evolution of Mn and Fe during the electrochemical cycling. The sXAS analysis reveals the evolving Mn oxidation states in LiMn0.5Fe0.5PO4. We found that electrochemically inactive Mn2+ is formed on the electrode surface during cycling. Additionally, the signal indicates about 20% concentration of Mn4+ at the charged state, providing a strong experimental evidence of the disproportional reaction of Mn3+ to Mn2+ and Mn4+ on the surface of the charged LiMn0.5Fe0.5PO4 electrodes.

  17. Raman and photoluminescence spectroscopic detection of surface-bound Li(+)O2(-) defect sites in Li-doped ZnO nanocrystals derived from molecular precursors.

    PubMed

    Kirste, Ronny; Aksu, Yilmaz; Wagner, Markus R; Khachadorian, Sevak; Jana, Surajit; Driess, Matthias; Thomsen, Christian; Hoffmann, Axel

    2011-04-18

    We present a detailed study of Raman spectroscopy and photoluminescence measurements on Li-doped ZnO nanocrystals with varying lithium concentrations. The samples were prepared starting from molecular precursors at low temperature. The Raman spectra revealed several sharp lines in the range of 100-200 cm(-1), which are attributed to acoustical phonons. In the high-energy range two peaks were observed at 735 cm(-1) and 1090 cm(-1). Excitation-dependent Raman spectroscopy of the 1090 cm(-1) mode revealed resonance enhancement at excitation energies around 2.2 eV. This energy coincides with an emission band in the photoluminescence spectra. The emission is attributed to the deep lithium acceptor and intrinsic point defects such as oxygen vacancies. Based on the combined Raman and PL results, we introduce a model of surface-bound LiO(2) defect sites, that is, the presence of Li(+)O(2)(-) superoxide. Accordingly, the observed Raman peaks at 735 cm(-1) and 1090 cm(-1) are assigned to Li-O and O-O vibrations of LiO(2). PMID:21433242

  18. Doping Cu{sub 2}O in Electrolyte Solution: Dopant Incorporation, Atomic Structures and Electrical Properties

    SciTech Connect

    Tao, Meng; Zhang, Qiming

    2013-11-24

    We have pursued a number of research activities between April 2010 and April 2011: A detailed study on n-type doping in Cu2O by Br; An analysis of natural resource limitations to terawatt-scale solar cells; Attempt to achieve a 1.4-eV direct band gap in Ni sulfides (NiSx); First-principles studies of doping in Cu2O and electronic structures of NiSx.

  19. Study on the electronic structures and the optical properties of the Mg-doped LiBaF 3 crystal

    NASA Astrophysics Data System (ADS)

    Qiao, Hailing; Liu, Tingyu; Zhang, Qiren; Cheng, Fang; Zhou, Xiuwen

    2010-04-01

    The most possible substituting positions of impurity magnesium ions in LiBaF 3 crystal are studied using the general utility lattice program (GULP). The electronic structures of Mg-doped LiBaF 3 crystal are studied within the framework of the fully relativistic self-consistent Dirac-Slater theory using DV-X α software. It is predicted that the most possible defect model is the [MgLi·+] in the Mg: LiBaF 3 crystal, which exhibits donor level in the forbidden band. The optical transition energy from the Mg 3s state to the Ba 5d state is 2.975 eV, which is very close to the experimental result. It is indicated that the 420 nm absorption band originates from [MgLi·+] and the presence of the 510 nm luminescence band is related to the defect cluster [MgLi·+] in the Mg:LiBaF 3 crystal too.

  20. Novel Proton Conducting Solid Bio-polymer Electrolytes Based on Carboxymethyl Cellulose Doped with Oleic Acid and Plasticized with Glycerol

    NASA Astrophysics Data System (ADS)

    Chai, M. N.; Isa, M. I. N.

    2016-06-01

    The plasticized solid bio-polymer electrolytes (SBEs) system has been formed by introducing glycerol (Gly) as the plasticizer into the carboxymethyl cellulose (CMC) doped with oleic acid (OA) via solution casting techniques. The ionic conductivity of the plasticized SBEs has been studied using Electrical Impedance Spectroscopy. The highest conductivity achieved is 1.64 × 10‑4 S cm‑1 for system containing 40 wt. % of glycerol. FTIR deconvolution technique had shown that the conductivity of CMC-OA-Gly SBEs is primarily influenced by the number density of mobile ions. Transference number measurement has shown that the cation diffusion coefficient and ionic mobility is higher than anion which proved the plasticized polymer system is a proton conductor.