Closed-Loop Recyclable Solid Polymer Electrolytes via Dynamic Lipoate Cross-Linking

Growing demand for electrochemical energy storage has intensified concerns over battery end-of-life disposal, driving an urgent need for recyclable electrolyte materials. Here, we report a photo-curable, chemically recyclable solid polymer electrolyte platform built on a bio-derived difunctional cross-linker, poly(ethylene glycol) bis(lipoate) (PEG-LP₂), prepared from naturally occurring α-lipoic acid. Visible-light-driven copolymerization of PEG-LP₂ with poly(ethylene glycol) methyl ether acrylate in the presence of an ionic liquid (BMITFSI, 45 wt%) yields flexible, ionically conductive membranes (1.30 mS cm^-1 at room temperature). The dynamic disulfide cross-linked network imparts both solid-like mechanical integrity and chemical recyclability. When assembled into symmetric supercapacitors, the optimized SPE-65 formulation retains ∼70% of its initial specific capacitance after 6000 galvanostatic cycles at 100 mA g^-1. Complete catalyst-assisted depolymerization is achieved using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) under mild, ambient conditions, and subsequent repolymerization regenerates ionically conductive membranes retaining ∼70% of the original conductivity (0.86 mS cm^-1). Together, the bio-derived lipoate cross-linker, catalytically assisted depolymerization, and regenerated electrochemical performance constitute a sustainable and recyclable SPE manufacture platform for next-generation supercapacitor applications.