Semi-interpenetrating-network all-solid-state polymer electrolyte with liquid crystal constructing efficient ion transport channels for flexible solid lithium-metal batteries

Abstract

The development of the solid-state polymer electrolytes (SPEs) for Li-ion batteries (LIBs) can effectively address the hidden safety issues of commercially used liquid electrolytes. Nevertheless, the unsatisfactory room temperature ion conductivity and inferior mechanical strength for linear PEO-based SPEs are still the immense obstacles impeding the further applications of SPEs for large-scale commercialization. Herein, we fabricate a series of semi-interpenetrating-network (semi-IPN) polymer electrolytes based on a novel liquid crystal (C6M LC) and poly(ethylene glycol) diglycidyl ether (PEGDE) via UV-irradiation at the first time. The LCs not only highly improve the mechanical properties of electrolyte membranes via the construction of network structure with PEGDE, but also create stable ion transport channels for ion conduction. As a result, a free-standing flexible SPE shows outstanding ionic conductivity (5.93 × 10⁻⁵ S cm⁻¹ at 30 °C), a very wide electrochemical stability window of 5.5 V, and excellent thermal stability at thermal decomposition temperatures above 360 °C as well as the capacity of suppressing lithium dendrite growth. Moreover, the LiFePO₄/Li battery assembled with the semi-IPN electrolyte membranes exhibits good cycle performance and admirable reversible specific capacity. This work highlights the obvious advantages of LCs applied to the electrolyte for the advanced solid lithium battery.