Electrolyte induced synergistic construction of cathode electrolyte interphase and capture of reactive free radicals for safer high energy density lithium-ion battery

As the energy density of battery increases rapidly, lithium-ion batteries (LIBs) are facing serious safety issue with thermal runaway, which largely limits the large-scale applications of high-energy-density LIBs. It is generally agreed that the chemical crosstalk between the cathode and anode leads to thermal runaway of LIBs. Herein, a multifunctional high safety electrolyte is designed with synergistic construction of cathode electrolyte interphase and capture of reactive free radicals to limit the intrinsic pathway of thermal runaway. The cathode electrolyte interphase not only resists the gas attack from the anode but suppresses the parasitic side reactions induced by electrolyte. And the function of free radical capture has the ability of reducing heat release from thermal runaway of battery. The dual strategy improves the intrinsic safety of battery prominently that the triggering temperature of thermal runaway is increased by 24.4 °C and the maximum temperature is reduced by 177.7 °C. Simultaneously, the thermal runaway propagation in module can be self-quenched. Moreover, the electrolyte design balances the trade-off of electrochemical and safety performance of high-energy batteries. The capacity retention of LiNi0.8Co0.1Mn0.1O2|graphite pouch cell has been significantly increased from 53.85% to 97.05% with higher coulombic efficiency of 99.94% at operating voltage extended up to 4.5 V for 200 cycles. Therefore, this work suggests a feasible strategy to mitigate the safety risk of high-energy-density LIBs without sacrificing electrochemical performances.