Xiang H.F.,CAS Hefei Key Laboratory of Materials for Energy Conversion |
Xiang H.F.,Anhui University of Science and Technology |
Yin B.,CAS Hefei Key Laboratory of Materials for Energy Conversion |
Wang H.,CAS Hefei Key Laboratory of Materials for Energy Conversion |
And 4 more authors.
Electrochimica Acta | Year: 2010
Room temperature ionic liquids (RTILs) with high safety characteristic usually have high viscosity and melting point, which is adverse for the application of RTIL-based electrolytes in Li-ion batteries. In this investigation, a promising RTIL, i.e. PP13TFSI consisting of N-methyl-N-propylpiperidinium (PP13) cation and bis(trifluoromethanesulfonyl)imide (TFSI) anion is synthesized. The effect of the content of Li salt in the electrolytes containing PP13TFSI and LiTFSI on the ionic conductivity and cell performance is investigated. The electrolyte of 0.3 mol kg-1 LiTFSI/PP13TFSI is recommended for its higher lithium transference number and discharge capacity in the LiCoO2/Li cell than other electrolytes. In addition, it is found that, by introducing 20% diethyl carbonate (DEC) as a co-solvent into pure RTIL electrolyte, the rate capability and low-temperature performance of the LiCoO2/Li cells are improved obviously, without sacrificing its safety characteristics. It suggests that a component with low viscosity and melting point, i.e. DEC, is necessary to effectively overcome the shortcomings of RTIL for the application in Li-ion batteries. © 2010 Elsevier Ltd. All rights reserved.
Zhou L.,University of Rhode Island |
Li W.,Novolyte Technologies |
Xu M.,University of Rhode Island |
Lucht B.,University of Rhode Island
Electrochemical and Solid-State Letters | Year: 2011
Lithium difluoro(oxalato) borate (LiDFOB) is a promising alternative lithium salt for lithium ion battery electrolytes. The ligand exchange reaction of LiDFOB to generate Lithium tetrafluoroborate (LiBF4) and lithium bis(oxalato)borate (LiBOB) was investigated by Nuclear Magnetic Resonance (NMR) spectroscopy. A thermally induced equilibrium exists between LiDFOB, LiBF 4 and LiBOB. The activation barrier for conversion of LiDFOB to LiBF4 and LiBOB is 137 KJ mol-1 and the equilibrium favors LiDOFB by 14 KJ mol-1. © 2011 The Electrochemical Society.
Chalasani D.,University of Rhode Island |
Li J.,Novolyte Technologies |
Jackson N.M.,Novolyte Technologies |
Payne M.,Novolyte Technologies |
Lucht B.L.,University of Rhode Island
Journal of Power Sources | Year: 2012
The preparation of methylene ethylene carbonate (MEC) and the incorporation of MEC into lithium ion batteries as an electrolyte additive were investigated. MEC is prepared in good yield by mercury catalyzed cyclization. Addition of low concentrations of MEC (1-2%) to 1 M LiPF 6 in 3:7 ethylene carbonate/ethyl methyl carbonate improves the capacity retention of lithium ion batteries cycled at elevated temperature (60 °C). Ex situ surface analysis (XPS and FTIR) of the electrodes supports the presence of poly(methylene ethylene carbonate) on the anode surface. Modification of the anode solid electrolyte interphase (SEI) correlates with significant improvements in the cycling performance at 60 °C. © 2011 Elsevier Ltd. All rights reserved. All rights reserved.