LiC₃N₄ Nanosheets Enhanced PEO-Based Solid Polymer Electrolytes: Unveiling Exceptional Electrochemical and Mechanical Properties

This study reports a high-performance composite solid polymer electrolyte by incorporating 2D LiC3N4 nanosheets into poly(ethylene oxide) (PEO), achieving an ionic conductivity of 1.95 × 10–4 S/cm at 50 °C and a wide electrochemical window of 5.2 V vs Li/Li+. The 2D nanostructure effectively suppresses PEO crystallization while creating continuous ion channels, yielding a high Li+ transference number (tLi+) of 0.65 and dendrite-resistant cycling stability (390 h in Li symmetric cells). When paired with LiFePO4 cathodes, full cells deliver 143 mAh/g of capacity with 90% retention, demonstrating superior performance compared to conventional PEO-based systems. This work establishes LiC3N4/PEO composites as promising electrolytes for flexible all-solid-state batteries.