Conductive Li~+ Moieties-Rich Cathode Electrolyte Interphase with Electrolyte Additive for 4.6 V Well-Cycled Li‖LiCoO_2 Batteries

摘要

Increasing the cut-off voltage of cathodes can improve the energy density ofLi‖LiCoO_2 batteries. However, the electrolyte and cathode suffer from oxidationand deterioration at high voltage, respectively, which lead to rapid batterydegradation. Herein, a uniform, highly Li~+ conductive cathode electrolyteinterphase (CEI) is constructed by using bis-(benzenesulfonyl)imide (BBSI)as an additive to stabilize Li‖LiCoO_2 batteries at 4.6 cut-off voltage withsuperior cycling and high-rate performance. Such a CEI is comprised of LiFand conductive Li+ moieties (e.g., Li_2S and Li_3N), which can improve the Li~+migration, alleviate cathode degradation, and other secondary degradationfactors caused by uneven local Li~+ intercalation/deintercalation. As expected,Li‖LiCoO_2 batteries with a 1% BBSI-containing electrolyte sustain 81.30% ofinitial capacity after 300 cycles at 0.5C, and 88.27% of initial capacity evenafter 500 cycles at 2C/3C.