In-situ generation of poly(ionic liquid) flexible quasi-solid electrolyte supported by polyhedral oligomeric silsesquioxane / polyvinylidene fluoride electrospun membrane for lithium metal battery

Quasi-solid electrolytes (QSEs) with high safety and flexibility can provide relatively high ionic conductivity and electrode/electrolyte interface compatibility. However, it also suffers from challenges of mechanical strength and stable cycling at room temperature. Herein, we design and prepare a poly(ionic liquid) electrolyte by in-situ thermally initiate crosslinking polymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMEM) and 1-vinyl-3-isobutyrate ethyl imidazole bis(trifluoromethylsulfonyl) imide (VBIM-TFSI) on the electrode surface with polyhedral oligomeric silsesquioxane (POSS)/polyvinylidene fluoride (PVDF) electrospun membrane as reinforcement separator. The POSS/PVDF electrospun membrane improves the electrolyte's mechanical strength without compromising the thickness, while the stable lithium-ion transport channels in the cross-linked network by PEGMEM and VBIM-TFSI enhance the ionic conductivity, achieving stable cycling of the battery at ambient temperature. The electrolyte with molar ratio of PEGMEM and VBIM-TFSI of 1–2 (QSE-P₁I₂) exhibits high ionic conductivity (2.15 × 10⁻⁴ S cm⁻¹, 30 °C) and stable electrode/electrolyte interface properties. Meanwhile, the batteries assembled with QSE-P₁I₂ realize stable cycle at room temperature. This study provides a promising strategy to utilize in-situ polymerization to improve electrode/electrolyte interfacial compatibility, improve ionic conductivity, and realize room temperature cycling of solid-state batteries.