Organic-inorganic composite electrolyte with in-situ polymerization poly(1,3-dioxolane) toward high-performance quasi-solid-state lithium metal batteries

Abstract

The sodium superionic conductor structure (NASICON) Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) is a promising active filler for its high ionic conductivity and air stability. Nonetheless, its large-scale application remains limited by chemical instability with lithium anodes. Herein, a novel poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based composite polymer electrolyte (CPE), designated as PPALx-D, is synthesized via a blade-casting method. This CPE comprises a conductive poly(poly(ethylene glycol) methyl ether methacrylate-co-(lithium 2-acrylamido-2-methylpropanesulfonic acid)) (P(PEGMEMA-co-AMPSLi)) matrix, inorganic LATP filler, and an in-situ polymerized 1,3-dioxolane (DOL) artificial interlayer. The physicochemical and electrochemical properties of the as-prepared CPEs are systematically characterized. Results show that the PPAL5-D CPE, despite being thinner and containing less liquid electrolyte, provides faster organic-inorganic Li⁺ transport channels and exhibits superior electrochemical compatibility with Li metal anodes. The PPAL5-D CPE achieves a high room-temperature (RT) ionic conductivity of 3.47× 10⁻⁴ S cm⁻¹ and a high Li⁺ transference number of 0.61. The assembled LFP|PPAL5-D|Li battery demonstrates significantly improved cycling stability, delivering a discharge capacity of 131.5 mAh g⁻¹ at 1C for 400 cycles at RT. This study proposes a feasible methodology for preparing organic-inorganic composite electrolytes, advancing the development of quasi-solid-state Li metal batteries (LMBs).