Enhancing Ion Conductivity and Robustness in Gel Polymer Electrolytes with a Semi-Interpenetrating Polymer Network Structure

In this study, we describe the synthesis of gel polymer electrolytes (GPEs) by casting a solution consisting of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and trimethylolpropane ethoxylate triacrylate (ETPTA) combined with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). The solution is subjected to thermal radical polymerization using different molar ratios. The resulting GPEs exhibit a semi-interpenetrating polymer network structure, as confirmed by morphological, structural, and electrochemical characterization. Among the various compositions investigated, the GPE with a molar ratio of PEGMA:ETPTA at 98:2, in the presence of 40 wt.% PVDF-HFP (relative to the total amount of PEGMA and ETPTA), demonstrates exceptional properties. It shows high ionic conductivity (1.46 × 10^-3 S cm^-1) and excellent tensile strength (6.28 MPa at an elongation at break of 156%). Moreover, the GPE exhibits electrochemical stability up to 4.7 V (vs. Li/Li+). Based on these electrochemical performance results, the synthesized GPEs show great potential as polymer electrolyte membranes in the field of energy storage.