Promoting long-term stability and high-temperature tolerance of lithium-ion batteries by introducing anion receptor additives into electrolyte

Layered ternary oxides LiNi_xMn_yCo_1-x-yO₂ is a promising cathode candidates for high-energy lithium-ion batteries (LIBs). However, severe side reaction between electrolyte and electrode limits its development at high temperature. Herein, an anion receptor additive tris(pentafluorophenyl)borane (TPFPB) is introduced in lithium difluoro(oxalato)borate (LiODFB)-based electrolyte to improve the long-term stability and high-temperature tolerance of LiNi_0.6Mn_0.2Co_0.2O₂ (NCM622)-based LIBs. Raman spectra and surface analysis show that the proportion of ODFB⁻ in Li⁺ solvated structure is strengthened due to the strong interaction between TPFPB and ODFB⁻, which leads to more ODFB⁻ enriching on the surface of NCM622. Moreover, TPFPB and ODFB⁻ with higher occupied molecular orbital energy level can be preferentially decomposed to form a robust inorganic-rich and well thermal stability CEI layer, which can alleviate solvents decomposition and thus reduce the loss of irreversible lithium. As a result, NCM622||Li battery with the TPFPB-containing electrolyte delivers good long-term stability with a capacity retention of 83.89 % after 100 cycles at the rate of 0.5C under 55 °C, much higher than 52.61 % of the one without TPFPB additives. This work provides a strategy to promote the long-term stability and high-temperature tolerance of LIBs by introducing anion receptor additives into the electrolyte, which has important implications for the development of high-performance LIBs.