Beyond Polyolefin Separators for Lithium-Ion Batteries

Abstract

Rechargeable lithium-ion batteries (LIBs) have garnered a great deal of attention, with the rapid growth of newly emerging applications such as wearable electronics, electric vehicles (EVs) and grid-scale electricity storage systems. Taking into account that a key factor governing battery performance is how to facilitate ion and electron transport, the roles of separator (membranes) in LIBs should not be underestimated. Currently, most widely used separators in LIBs are manufactured using polyolefin materials. These polyolefin separators have several advantageous attributes suitable for practical use in LIBs, however, their intrinsic limitations often raise significant concerns related to ion transport (cell performance) and electrical isolation (cell safety) between the electrodes. In this presentation, we demonstrate a new class of 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 the new separators to LIBs is explored, with a particular focus on high-rate capability and cycling performance that are in urgent need for forthcoming EV batteries.