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

Abstract 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.