Separator Design for High-Performance Supercapacitors: Requirements, Challenges, Strategies, and Prospects

Supercapacitors have attracted considerable attention as promising power sources for applications that need energy pulses during the short periods of time. The separator is one of the most important parts of a supercapacitor and plays a critical role in avoiding internal electronic short circuits and constructing safe and high-performance supercapacitors. Currently, commercial cellulose-based separators are limited by the low mechanical strength or high self-discharge rate, while commercial polyolefin-based separators suffer from the poor thermal stability. Recently, tremendous efforts have been devoted to developing advanced separators with high performance. To better understand the contributions of the separators on improving the electrochemical performance and safety of supercapacitors, we discussed the fundamental requirements for ideal separators and the effects of raw materials, preparation strategies, and properties of separators on the electrochemical performance of supercapacitors. Outlooks and future directions for the rational design of advanced separators are also provided.