Evaluation and comparison of the physical and electrochemical properties of lithium-ion battery separators

The separator is one of the core inner components of the lithium-ion battery, and its performance directly affects the electrochemical properties, life, and safety performance of the battery. In this research, the physical and electrochemical properties of polyethylene (PE), polypropylene (PP) / PE/PP multilayer, (PP), and aluminum oxide ceramic-coated PE (PE–Al2O3) separators were analyzed and compared in detail. Among the separators, the PE–Al2O3 separator exhibited better performance pertaining to puncture strength, thermal stability, wettability, and ionic conductivity. However, its tensile strength is slightly lower than that of the PP/PE/PP separator. The surface of the PE, PP, and PP/PE/PP separators exhibited a large number of submicron pores. Alumina particles were uniformly distributed on the surface of the PE–Al2O3 separator, and a large number of clear pores were presented between the alumina particles. The PP/PE/PP separator exhibited the best tensile properties among the separators in the mechan