Effects of Tris(Pentafluorophenyl) Borane (TPFPB) as an Electrolyte Additive on the Cycling Performance of LiFePO4Batteries

Both the cycling performance of LiFePO4 cells prepared with Li or MCMB anodes, and 1 M LiPF6 in EC/DEC electrolytes with/without adding tris(pentafluorophenyl) borane (TPFPB) are used to ascertain the effects of the TPFPB additive. It is found that the cycling performance of the LiFePO4/MCMB cell is improved significantly by the TPFPB additive at 60°C, though the influence of the additive on the cycling performance of LiFePO4/MCMB cell at 25°C and LiFePO4/Li at 25 and 60°C are indistinct. The results of soak study, FTIR, and XPS analyzes for the electrodes obtained from cycled LiFePO4/Li and LiFePO4/MCMB cells reveal that the improvement on cycling performance of the LiFePO4/MCMB cell at 60°C can be mainly attributed to the reduction of LiF content in SEI layer and the layer growth rate by adding TPFPB to enhance re-dissolution of lithium salts.