Effect of methyl acetate on low-temperature performance of LiCo_(1/3)Ni_(1/3)Mn_(1/3)O_2 cathode and graphite anode

摘要

Li/LiCo_(1/3)Ni_(1/3)Mn_(1/3)O_2 and Li/graphite half cells filled with methyl acetate (MA) with 1M LiPF_6 function very well. Cells filled with 1 M LiPF_6 in EC:DMC:EMC:MA(1:1:1:3) show good capacity retention 147.5 mAh g~(-1) after 50 cycles at 25°C. Electrochemical performance of Li-ion batteries is analyzed via the constant current charge-discharge test and cyclic voltammetry. It is found that adding a certain amount of MA improves the compatibility of electrolyte with electrodes. This study further shows that cells with 1M LiPF_6 in EC:DMC:EMC:MA (1:1:1:3 v/v%) greatly improves the low-temperature performance in LiCo_(1/3)Ni_(1/3)Mn_(1/3)O_2 cells. The capacity retention of the cell used this electrolyte is 92.2%, comparing to 86.8% of that without MA at -20°C.