Conductive Li+ Moieties-Rich Cathode Electrolyte Interphase with Electrolyte Additive for 4.6 V Well-Cycled Li||LiCoO2 Batteries

Increasing the cut-off voltage of cathodes can improve the energy density of Li||LiCoO2 batteries. However, the electrolyte and cathode suffer from oxidation and deterioration at high voltage, respectively, which lead to rapid battery degradation. Herein, a uniform, highly Li+ conductive cathode electrolyte interphase (CEI) is constructed by using bis-(benzenesulfonyl)imide (BBSI) as an additive to stabilize Li||LiCoO2 batteries at 4.6 cut-off voltage with superior cycling and high-rate performance. Such a CEI is comprised of LiF and conductive Li+ moieties (e.g., Li2S and Li3N), which can improve the Li+ migration, alleviate cathode degradation, and other secondary degradation factors caused by uneven local Li+ intercalation/deintercalation. As expected, Li||LiCoO2 batteries with a 1% BBSI-containing electrolyte sustain 81.30% of initial capacity after 300 cycles at 0.5C, and 88.27% of initial capacity even after 500 cycles at 2C/3C.

Automated summary

Increasing the cut-off voltage of cathodes improves the energy density of Li||LiCoO2 batteries, but also leads to rapid battery degradation due to oxidation and deterioration. However, by using bis-(benzenesulfonyl)imide (BBSI) as an additive, a uniform and highly Li+ conductive cathode electrolyte interphase (CEI) is constructed, which stabilizes the batteries at 4.6 cut-off voltage and exhibits superior cycling and high-rate performance. The CEI, consisting of LiF and conductive Li+ moieties, improves Li+ migration, alleviates cathode degradation, and reduces other secondary degradation factors. Li||LiCoO2 batteries with 1% BBSI-containing electrolyte sustain 81.30% of initial capacity after 300 cycles at 0.5C, and 88.27% of initial capacity even after 500 cycles at 2C/3C.