Abstract: B-containing electrolyte additives are widely used to enhance the cycle performance at low temperature and the rate capability of lithium-ion batteries by constructing an efficient cathode electrolyte interphase (CEI) to facilitate the rapid Li⁺ migration. Nevertheless, its wide-temperature application has been limited by the instability of B-derived CEI layer at high temperature. Herein, dual electrolyte additives, consisting of lithium tetraborate (Li₂TB) and 2, 4-difluorobiphenyl (FBP), are proposed to boost the wide-temperature performances of LiNi_0.6Co_0.2Mn_0.2O₂ (NCM) cathode. Theoretical calculation and electrochemical performances analyses indicate that Li₂TB and FBP undergo successive decomposition to form a unique dual-layer CEI. FBP acts as a synergistic filming additive to Li₂TB, enhancing the high-temperature performance of NCM cathode while preserving the excellent low-temperature cycle stability and the superior rate capability conferred by Li₂TB additive. Therefore, the capacity retention of NCM||Li cells using optimal FBP-Li₂TB dual electrolyte additives increases to 100% after 200 cycles at -10 °C, 99% after 200 cycles at 25 °C, and 83% after 100 cycles at 55 °C, respectively, much superior to that of base electrolyte (63%/69%/45%). More surprisingly, galvanostatic charge/discharge experiments at different temperatures reveal that NCM||Li cells using FBP-Li₂TB additives can operate at temperatures ranging from -40 °C to 60 °C. This synergistic interphase modification utilizing dual electrolyte additives to construct a unique dual-layer CEI adaptive to a wide temperature range, provides valuable insights to the practical applications of NCM cathodes for all-climate batteries.

Key words: Nickel-rich cathode, Dual electrolyte additives, Lithium-ion batteries, Wide temperature application, Cathode electrolyte interphase