Synergistic effect of sulfolane-based composite polymer electrolyte and vinylidene carbonate/lithium difluoro(oxalato)borate interface modification on LiCoO2 cathode

LiCoO 2 (LCO) is a prominent high-voltage cathode material due to its exceptional energy density and impressive theoretical specific capacity of 274 mAh g −1 . However, challenges such as irreversible structural phase transitions, loss of reactive oxygen, and cobalt dissolution can lead to unstable interfaces between the electrolyte and the LCO cathode. In this study, sulfolane (SUL)-based composite polymer electrolytes (CPEs) were synthesized through in-situ polymerization, and the LCO cathode was modified using vinylidene carbonate (VC) and lithium difluoro(oxalato)borate (LiDFOB). The synergistic effects of SUL and VC/LiDFOB facilitated the formation of a more stable cathode-electrolyte interface (CEI) layer. Consequently, the Li/EFHTL-15 %SUL/LCO-VC-LiDFOB cell demonstrated excellent reversible cycling performance, achieving 86.36 % capacity retention after 300 cycles at 0.5C within a voltage range of 2.8–4.4 V at 25 ℃. This work provides a viable approach for enhancing the interface stability of the LCO cathode in CPEs.