A high-temperature stable ceramic-coated separator prepared with polyimide binder/Al2O3 particles for lithium-ion batteries

•The CCS-PI shows no thermal shrinkage at 160 °C for 0.5 h.•The cells with the CCS-PI show a stable voltage over 160 °C.•Batteries with the CCS-PI show stable cyclic and good rate performance.

An effective and practical way to develop the lithium-ion power batteries with better safety performance is to increase the thermal shrinkage resistance of the separator at high temperature. In this work, a ceramic coating separator (CCS-PI) is manufactured by coating Al2O3 ultrafine powder and thermal stable polyimide binder onto the surface of the porous polyethylene (PE) membrane. CCS-PI exhibits no thermal shrinkage up to 160 °C in dry state and maintains stable when packed inner the cells up to 165 °C. Meanwhile CCS-PI hasn't been punctured during the hot metal rod piercing testing. The above results all prove that the CCS-PI has high thermo-stability. In addition, the CCS-PI presents higher electrolyte uptake, better wettability with the electrolyte and enabled high ionic conductance when it is saturated with liquid electrolyte. The cells with this CCS-PI show good cyclic performance. Therefore, as-prepared CCS-PI is a promising separator to improve thermal safety and capacity retention for lithium-ion power batteries.