A glycerol triglycidyl ether cross-linker assisting an in situ thermally polymerized gel polymer electrolyte for advanced lithium metal batteries

Abstract

In situ polymerization of 1,3-dioxolane (DOL) based liquid precursor as gel polymer electrolyte (GPE) is a promising strategy to prepare solid-state lithium metal batteries. However, the poor structural stability and low lithium ion transference number (t_Li⁺) of the linear poly(1,3-dioxolane) (PDOL) GPE limit its commercial application. Herein, a cross-linked GPE is prepared by lithium salt initiated in situ thermal polymerization of DOL and glycerol triglycidyl ether (GTE) monomers. A fluoroethylene carbonate (FEC) liquid plasticizer is further introduced to promote the dissociation of lithium salts, and the obtained PDOL–FEC–GTE composite electrolyte exhibits ionic conductivity of 2.1 × 10⁻⁴ S cm⁻¹, t_Li⁺ of 0.58 and wide electrochemical stability window of 5.1 V. Li‖Li symmetric cell is stably operated for 790 h at 1.0 mA cm⁻² and 1.0 mA h cm⁻². LiFePO₄|PDOL–FEC–GTE|Li full cell delivers a discharge specific capacity of 120.8 mA h g⁻¹ after 200 cycles at a current rate of 1C with a capacity retention of 84.1%. This work provides new ideas for accelerating the practical application of solid-state lithium metal batteries.