Lithium-compatible and air-stable vacancy-rich Li9N2Cl3 for high–areal capacity, long-cycling all–solid-state lithium metal batteries

Attaining substantial areal capacity (>3 mAh/cm²) and extended cycle longevity in all–solid-state lithium metal batteries necessitates the implementation of solid-state electrolytes (SSEs) capable of withstanding elevated critical current densities and capacities. In this study, we report a high-performing vacancy-rich Li₉N₂Cl₃ SSE demonstrating excellent lithium compatibility and atmospheric stability and enabling high–areal capacity, long-lasting all–solid-state lithium metal batteries. The Li₉N₂Cl₃ facilitates efficient lithium-ion transport due to its disordered lattice structure and presence of vacancies. Notably, it resists dendrite formation at 10 mA/cm² and 10 mAh/cm² due to its intrinsic lithium metal stability. Furthermore, it exhibits robust dry-air stability. Incorporating this SSE in Ni-rich LiNi_0.83Co_0.11Mn_0.06O₂ cathode-based all–solid-state batteries, we achieve substantial cycling stability (90.35% capacity retention over 1500 cycles at 0.5 C) and high areal capacity (4.8 mAh/cm² in pouch cells). These findings pave the way for lithium metal batteries to meet electric vehicle performance demands.