Embedding Antiperovskite Nanophases into Polymer Hosts Boosts Ionic Conductivity and Interfacial Compliance for All-Solid-State Lithium Metal Batteries

Abstract

All-solid-state batteries (ASSBs) have emerged as a safer and more energy-dense alternative to conventional liquid-electrolyte batteries. In this study, a composite solid electrolyte (CSE) was developed by incorporating Li3OCl (lithium-rich antiperovskite, LiRAP) into a poly(ethylene oxide)-LiTFSI matrix to address the limitation of single-phase solid electrolytes. The Li3OCl was selected for its good ionic conductivity, simple ball-milling synthesis, and ability to enhance Li-ion transport in the polymer matrix. The resulting CSE exhibits reduced interfacial resistance and enhanced ionic conductivity at room temperatures, enabling stable cycling performance. Li stripping/plating tests confirm its compatibility with lithium metal, showing stable cycling without short circuits over 100 cycles. In addition, the Li//LFP cell using this CSE maintains 86.2 % of its initial capacity after 100 cycles at 25 °C. The work highlights the synergistic benefits of combining LiRAP with PEO, providing a practical route toward improved all-solid-state lithium batteries.