Solvent-Free Extrusion of Poly(Ethylene Oxide)-Polycarbonate All-Solid-State Electrolytes for Li-Metal Batteries: Uv-Crosslinking Impact on the Electrochemical Performance

Abstract

All-solid-state lithium-ion batteries are one of the most promising candidates for next-generation energy storage systems. A challenge remains in identifying solid polymer electrolytes (SPE) with high ionic conductivity. We introduce an advanced, solid polymer electrolyte (SPE) composed of poly(ethylene oxide) (PEO) and poly(ethylene carbonate) (PEC), fabricated by solvent-free extrusion and 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. Li||Li cells demonstrate outstanding stripping/plating performance across a current density range of 0.025 to 0.2 mA cm⁻2 at 40 and 70 °C, with stable cycling for over 600 hours at 0.05 mA cm⁻2 and without Li dendrite growth at 70 °C. Degradation is analysed via nuclear magnetic resonance (NMR) spectroscopy to evaluate the impact of UV crosslinking, while impedance spectroscopy investigates the electronic and ionic transport properties during oxidation and reduction processes. The lithium metal polymer cells assembled with a LiFePO4-based composite catholyte demonstrate near-full specific capacity at low rates (up to 157 mAh g−1 at C/5), and excellent rate capability at 70 °C. This strategy offers a promising approach for the design of solid-state electrolytes that can enhance the performance of the batteries.

Keywords: solid-state battery, Lithium Battery, Polymer electrolyte, poly(ethylene oxide), solvent-free extrusion