Revealing the Compositional and Interfacial Chemistry of Antiperovskite Solid Electrolytes for Li-Metal Battery Applications

Abstract Solid-state electrolytes with high ionic conductivity and excellent interfacial stability are essential for the development of next-generation all-solid-state lithium batteries. Among all known lithium-ion conductors, lithium-rich antiperovskite (LRAP) Li3ClO exhibits high ionic conductivity, mechanical processability, low cost, and promising potential for compatibility with lithium metal anodes. In this work, we systematically investigate the structural, thermodynamic, ionic transport, and interfacial electrochemical stability of LRAP Li3ClO using a combination of density functional theory calculations and ab initio molecular dynamics simulations. Our results show that crystalline Li3ClO is a metastable phase at 0 K and becomes thermodynamically accessible at temperatures above 425 K. The antiperovskite framework enables fast Li+ migration along interconnected channels in three dimensions. At the same time, the amorphous counterpart, formed via glassification, exhibits even higher ionic conductivity due to the broader and shorter lithium-ion migration pathways. Aliovalent doping (e.g., Ba2+) further promotes lithium-ion mobility with additionally introduced mobile lithium vacancies, at the cost of a reduced band gap, especially in its amorphous phase. Moreover, interfacial modeling indicates that Li3ClO decomposes spontaneously upon direct contact with metallic lithium, which explains the self-discharge observed in previous experiments. To stabilize the interface between lithium metal and the antiperovskite Li3ClO, we propose an interface-morphogenesis strategy that introduces the metal Na phase, effectively suppressing side reactions and improving chemical stability. These findings provide insights into the design of lithium-rich antiperovskite electrolytes and promising strategies for interface engineering in solid-state lithium-ion batteries.