High-safety separators for lithium-ion batteries and sodium-ion batteries: advances and perspective

Lithium-ion batteries and sodium-ion batteries have obtained great progress in recent decades, and will make excellent contribution in portable electronics, electric vehicles and other large-scale energy storage areas. The safety issues of batteries have become increasingly important and challenging because of frequent occurrence of battery accidents. The separator is an indispensable component in lithium-ion batteries and sodium-ion batteries and directly affects the electrochemical performance and, especially, safety. It is imperative to develop high-safety separators for rechargeable lithium-ion batteries and sodium-ion batteries. This review summarizes and discusses lithium-ion battery separators from a new perspective of safety (chemical compatibility, heat-resistance, mechanical strength and anti-dendrite ability), the development status of sodium-ion battery separators and the difference between lithium-ion battery separators and sodium-ion battery separators. The key challenges and perspectives in the development direction of high-safety separators are outlined.