Novel poly(epichlorohydrin)-based matrix for monolithic ionogel electrolyte membrane with high lithium storage performances

Abstract

Based on gelling matrices and ionic liquids (ILs), monolithic ionogel electrolyte membranes (MIEMs) have become a research focus. However, further application is limited by lack of functional matrices. Herein, we proposed the introduction of an ionized polymer, i.e., polyether polymer with side-chain ionic groups obtained via the reaction of quaternary ammonium with uncrystallizable poly (epichlorohydrin) (PECH), as the matrix into the gels to balance the mechanical properties and the ionic conductivity. In combination with lithium bis-(fluorosulfonyl) imide (LiFSI) and 1-ethyl-3-methylimidazolium bis-(fluorosulfonyl)-imide (EMImFSI) via a solvent casting technique, a flexible MIEM was successfully prepared. The as-obtained MIEM exhibited good thermal stability (up to about 250 °C) and a high ionic conductivity of 1.21 mS cm⁻¹ at 20 °C. Moreover, Li|LiFePO₄ coin cells using this MIEM delivered high capacity (150.0 mA h g⁻¹ at 0.2C) with good cycling stability, and an excellent C-rate response. This work discloses a novel and paramount route to exploit PECH-based MIEMs for Li storage, as well as energy storage systems beyond Li.