One-Step Synthesis of PVDF-HFP/PMMA-ZrO₂ Gel Polymer Electrolyte to Boost the Performance of a Lithium Metal Battery

Abstract

The safety issue of lithium batteries based on liquid electrolytes has become the focus of attention, especially when the batteries are exposed to mechanical, thermal, or electrical abuse conditions. To address this issue, gel polymer electrolytes (GPEs) have attracted widespread interest due to the property of solid–liquid coexistence with higher ionic conductivity, flexibility, and safety. In this work, a poly(vinylidene-fluoride-co-hexafluoropropylene) (PVDF-HFP)/poly(methyl methacrylate) (PMMA) matrix GPE, containing bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) and spherical zirconium dioxide (ZrO2) nanoparticles, is successfully designed and synthesized by a simple one-step solution-casting route. It has been found that the obtained PVDF-HFP/PMMA-ZrO2-6% (PPZ-6%) electrolyte film possesses an excellent tensile strength of 37.7 MPa. Moreover, the PPZ-6% GPE not only has a high ionic conductivity of 1.46 × 10–3 S cm–1 at 25 °C but also presents excellent interface compatibility in an Li||Li symmetrical battery. The LiFePO4||Li cell assembled with the PPZ-6% GPE exhibits good cyclic stability at room temperature, e.g., a high discharge specific capacity of 153.0 mAh g–1, and a high Coulombic efficiency of 99% after 200 cycles at 0.5 C. Therefore, this organic–inorganic hybrid GPE modified with spherical ZrO2 nanoparticles reveals a good application prospect for high-performance lithium metal batteries (LMBs).