Improved LiMn_2O_4/Graphite Li-Ion Cells at 55 deg C

摘要

Sodium phosphate additives and mixed electrolytes of Li(C_2F_5SO_2)_2N (LiBETI) and LiPF_6 were examined to improve cycle performances of Li_(1.04)Mn_(1.96)O_4/graphite cells at high temperatures. The cycle performance of those cells exceeded 80 percent at 100 cycles at 55 deg C in an optimum combination of a 0.975 M LiBETI and 0.025 M LiPF_6/ethylene carbonate (EC):dimethylcarbonate (DMC) (1:2) electrolyte solution containing 5 percent of Na_4P_2O_7 or 5 percent of Na_5P_3O_(10) additive. Such a cycle performance is considered to fulfill the requirement for practical use.