Thermal Stabilities of Some Lithium Salts and Their Electrolyte Solutions With and Without Contact to a LiFePO4 Electrode

Thermal stabilities of different lithium salts and the roles of the salts on the thermal behaviors of their based electrolytes and electrolyte-LiFePO(4) coexisting systems were analyzed by a C80 microcalorimeter in this paper. For the salts lithium hexafluorophosphate (LiPF(6)), lithium tetrafluoroborate (LiBF(4)), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and lithium bis(oxalate)borate (LiBOB), there is no exothermic behavior was detected. The mixture systems without lithium salts present relatively stable thermal behavior. The thermal stability of solvents is greatly reduced after the addition of lithium salt, especially for the LiPF(6)-based electrolyte. The special structure and composition of LiBOB enable the LiBOB-based electrolyte to show excellent thermal stability. The thermal stability of the electrolyte-LiFePO(4) coexisting system is mainly determined by the electrolyte not by LiFePO(4) and the LiBOB-based coexisting system shows better thermal characteristics. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3473789] All rights reserved.