Evolution from passive to active components in lithium metal and lithium-ion batteries separators

Lithium batteries are emerging as key contenders for next-generation energy storage due to their high energy density, and promising advances in consumer electronics and electric vehicles. A critical component in lithium batteries is the separator, which not only facilitates ion transport between electrodes but also prevents dendrite formation that can lead to short-circuits which is a major barrier to widespread adoption. This review examines the evolution and current state of separators for lithium-ion and lithium-metal batteries, emphasizing their role in enhancing performance and safety. It addresses the failure mechanisms that can undermine separator effectiveness and highlights the importance of developing advanced materials to overcome these challenges. Future advancements in lithium battery technology are closely tied to innovations in separator design. By exploring recent advancements and emerging trends, this review aims to outline potential development paths for improving separator materials. It seeks to address key issues and propose novel approaches, ultimately contributing to the development of safer, more efficient, and commercially viable lithium metal batteries.