Functional separator materials of sodium-ion batteries: Grand challenges and industry perspectives

Sodium batteries represent a new generation of energy storage technology to replace lithium-ion batteries. The separator is one of the key components that directly affects battery performance. The mechanical properties and chemical stability of commercial separators are excellent, but the performance of wettability and compatibility is insufficient for use in sodium ion battery systems. This article summarizes the optimal performance of separators in terms of their working principle and structure of sodium ion batteries. In addition, polyolefin separators, cellulose separators and glass fiber separators are reviewed and discussed. Finally, the industrialization process and future trends of sodium batteries are outlined.