Tris (pentafluorophenyl) phosphine: A dual functionality additive for flame-retarding and sacrificial Oxidation on LiMn2O4 for lithium ion battery

Tris (pentafluorophenyl) phosphine (TPFPP) additive possesses a dual functionality. The first of which is aimed at decreasing the flammability of the electrolyte, while the second is directed at the inhibition of the oxidative decomposition of electrolyte on cathode materials in lithium-ion batteries. The properties of the electrolyte containing TPFPP and the enhancements of cycling performance of Li/LiMn2O4 cells are investigated via a combination of electrochemical methods, self-extinguishing time (SET), differential scanning calorimeter (DSC), as well as density functional theory (DFT) computations. It is found that the incorporation of TPFPP to 1.0 M LiPF6 in 1:1:1 (v/v/v) ethylene carbonate/dimethyl carbonate/diethyl carbonate improves the thermal stability and decrease the flammability of the electrolyte. In addition, the initial discharge capacity and cycling stability of Li/LiMn2O4 is improved as well. The improved cycling performance with TPFPP added can be ascribed to the participation in surface layer formation process with incorporation of TPFPP. DFT theoretical computations are in good agreement with the modified cyclic voltammetry behavior of electrolyte with and without TPFPP additive on LiMn2O4 and graphite electrodes. (C) 2013 Elsevier B.V. All rights reserved.