Dry extrusion of poly(ethylene oxide)-polycarbonate all-solid-state electrolytes for Li-metal batteries: effect of UV-crosslinking on the electrochemical performance

All-solid-state lithium-based batteries are amongst the most promising candidates for next-generation energy storage systems. A challenge remains in identifying solid polymer electrolytes (SPE) with high ionic conductivity. Here, we introduce an advanced SPE composed of poly(ethylene oxide) (PEO) and poly(ethylene carbonate) (PEC), fabricated by simple, up-scalable solvent-free extrusion followed by UV crosslinking. This method yields flexible, self-standing electrolytes with remarkable thermal and mechanical stability, ensuring non-flammability and structural integrity, while also being scalable for industrial production. Symmetric Li||Li cells demonstrate outstanding stripping/plating performance across a current density range of 0.025–0.2 mA cm−2 at both 40 and 70 °C, exhibiting stable cycling for over 600 h at 0.05 mA cm−2 and neglibile Li dendrite growth at 70 °C. Degradation is analysed using nuclear magnetic resonance (NMR) spectroscopy to evaluate the impact of UV crosslinking, while impedance spectroscopy investigates the electronic and ionic transport properties during initial oxidation and reduction processes. The lithium metal polymer cells assembled with a high-loading LiFePO4-based composite catholyte demonstrate near-full specific capacity at low rates (up to 157 mAh g−1 at C/5), and show excellent rate capability at 70 °C, paving the way for the design of the next-generation solid-state batteries with enhanced performance.