A roadmap of battery separator development: Past and future

The battery separator is one of the most essential components that highly affect the electrochemical stability and performance in lithium-ion batteries. In order to keep up with a nationwide trend and needs in the battery society, the role of battery separators starts to change from passive to active. Many efforts have been devoted to developing new types of battery separators by tailoring the separator chemistry. In this article, the overall characteristics of battery separators with different structures and compositions are reviewed. In addition, the research directions and prospects of separator engineering are suggested to provide a solid guideline for developing a safe and reliable battery system.