Enhanced Safety Performance of Automotive Lithium‐Ion Batteries with Al₂O₃‐Coated Non‐Woven Separator

Abstract

Abstract Thermal runaway (TR) is the fatal safety defects that hinder the wide application of automotive batteries. The short circuit caused by shrinkage of separators under high temperatures leads to TR. In this paper, we demonstrate the robust thermal stability of an Al 2 O 3 coated non‐woven polyethylene terephthalate (PET) separator. The shrinkage ratio of the Al 2 O 3 coated separator has been compared with the non‐coated polyethylene (PE) separator by differential scanning calorimetry (DSC), thermogravimetry (TG ) and heat nail tests. Automotive lithium‐ion batteries (LIBs) with large capacities have been used to conduct the simulations of nail penetration. TR is found to be triggered by Joule heat generation during the shrinkage of the separators. The separator with lower shrinkage retains highly stable dimension against wide range temperature changes. This feature enables the Al 2 O 3 coated separator to prevent inner short circuits. The improved safety performance indicates a promising prospect of Al 2 O 3 coated non‐woven separators in LIBs.