Alumina nanocoating of polymer separators for enhanced thermal and electrochemical performance of Li–ion batteries

Abstract

Abstract A chemical‐wet impregnation method was adopted in this study to synthesize alumina‐coated separators using commercially available alumina nanoparticles and poly (vinylidene fluoride‐hexafluoro‐propylene) binder to further improve the safety and performance of lithium–ion batteries (LIBs). Three trilayered polymer separators were uniformly coated with alumina nanoparticles with different densities. It was shown that the alumina‐coated nanolayers significantly improved electrolyte affinity, mass uptake of electrolyte, thermal resistance, and dimensional stability of the separators. The discharge capacity of Li 4 Ti 5 O 12 anode with alumina‐coated separators was evaluated to be 166 mAh g −1 at 0.1 C and 160 mAh g −1 at 1 C . The alumina‐coated layers boasted ionic conductivity within the LIB's architecture and reduced internal resistance. The thermal shrinkage of alumina‐coated separators was greatly decreased, compared with the bare (as‐received) membranes because the nanocoating layer served as a robust and protective layer providing a superior thermal insulation without adversely affecting mass transport characteristics within the LIBs' internal architecture.