Kilogram-scale synthesis and interface engineering of oxyhalide solid electrolytes for high-performance all-solid-state batteries

All-solid-state batteries (ASSBs) employing inorganic solid-state electrolytes (SSEs) offer superior safety and high energy density. However, conventional synthesis methods based on high-energy ball milling or high-temperature sintering are energy-intensive and unsuitable for large-scale manufacturing, while the discrete solid-solid contact between electrolyte and cathode active materials limits ionic transport. Here, a mechano-thermal method was developed to trigger the synthesis of oxyhalide electrolytes within 2 min, enabling cost-effective, scalable production. Furthermore, the low-melting LiAlCl_2.5O_0.75 electrolyte was utilized to form uniform coatings and interfacial filling layers on NCM88 (LiNi_0.88Co_0.09Mn_0.03O₂) particles through hot-press melting. The resulting ASSBs exhibit excellent electrochemical performance, achieving an initial Coulombic efficiency of 95.2 % and a discharge capacity of 215 mAh g^-1, and stable operation at 20 mA cm^-2. This work provides a practical route toward scalable SSEs synthesis and improved interfacial integration, contributing to the development of high-performance ASSBs.