Beyond Polyolefin Battery Separator Membranes

Abstract

The ever-increasing demand for electric vehicles (EVs), stationary energy storage systems (ESSs), and portable smart electronics inspires the relentless pursuit of advanced rechargeable power sources with reliable/sustainable electrochemical performance and safety tolerance. Taking into account that a key factor governing battery performance is how to facilitate ion and electron transport, the roles of separator membranes in batteries should not be underestimated. Battery separator membranes offer ion-conducting routes between electrodes and also electronically isolates the electrodes to prevent internal short-circuit failure (resulting in cell fire or explosion). Currently, most widely used separators in rechargeable batteries are manufactured using polyolefin materials. The polyolefin separators have several advantageous attributes suitable for practical use in lithium-ion batteries (LIBs), however, their intrinsic limitations often raise significant concerns related to ion transport (cell performance) and electrical isolation (cell safety) between the electrodes. Numerous approaches have been adopted to resolve the aforementioned problems, including ceramic-coated polyolefin separators, nonwoven-based separators, and nanofiber separators. In this presentation, we present a new class of non-polyolefin separators featuring the well-tailored porous structure, thermal stability and chemical functionality that lie far beyond those accessible with conventional polyolefin separators. Based on comprehensive understanding of membrane structure, and properties, applicability of these new separators to LIBs is explored, with a particular focus on high-rate capability and cycling performance that are in urgent need for forthcoming smart electronics and EV bateries.