Nonsolvent-Induced Phase Separation Polyimide/Polymeric Ionic Liquid Separators for High-Performance and Safe Lithium Metal-Based Batteries

Abstract

Lithium-ion battery separator safety has grown significantly in recent years, and preventing or minimizing thermal runaway in Li-ion batteries, especially during rapid charging and discharging, is a crucial problem. Therefore, there is a pressing need to develop high-safety thermotolerant separators that can guarantee high ion transport while also enabling homogeneous Li+ fluxes for the inhibition of Li dendritic growth. The nonsolvent-induced phase separation (NIPS) technique is used here to create a novel kind of polyimide (PI)/polymeric ionic liquid (PIL) separator that can be used as a thermotolerant separator alternative to commercial polyolefin-based separators. Without encountering a problem with other types of thermotolerant separators, whether they have nanopores or micropores, the fabricated PI/PIL separator with homogenous and nanosized pores exhibits high electrolyte adsorption/retention, ionic conductivity, mobility, and electrochemical properties in addition to typical high mechanical and thermal properties. Moreover, the PI/PIL separator displays excellent resistance for dendrite growth, and when integrated into the NCM811/Li cell demonstrates excellent cycling stability and rate performance. This work offers a significant method for creating a thermotolerant separator that addresses the issues of Li metal batteries, such as the absence of a high-performance and high-safety separator.

Keywords: Polyimide, Thermotolerant separator, Nonsolvent-induced phase separation, Lithium metal-battery