Porous polyetherimide separators controlled in‐situ by tetrabutyl titanate as polymer electrolyte with ionic liquid for lithium‐oxygen batteries

Due to its advantages in specific capacity, lithium-oxygen batteries are expected to increase the recharge mileage of electric vehicles. However, the safety and cycle stability problems of lithium-oxygen batteries have not been completely resolved. Herein, through the non-solvent-induced phase separation method combined with the in-situ hydrolysis modification strategy of tetrabutyl titanate, a type of polyetherimide (PEI) separator with typical finger-shaped pores and honeycomb-shaped supporting layer pore structure was prepared. After being infiltrated by EMIM-BF4 ionic liquid electrolyte, the ionic conductivity of the separator can reach 0.75 mS cm−1. Due to the low crystallinity, high thermal stability, and stable ion transport pore structure of the separators, the assembled lithium-oxygen batteries can stably cycle for more than 75 cycles under the condition of a limit of 1000 mAh g−1. In addition, under the strategy of high-performance cathode catalysts and electrolyte additives, the application of the porous PEI separators in lithium-oxygen batteries will be further expanded.