UC Berkeley

A key requirement for achieving high-energy density in solid-state batteries is highly efficient cycling of an alkali metal anode in a safe manner. Herein, we combine first-principles calculations and experimental characterizations to identify a protective hydrate coating for Na3SbS4 that leads to a passivating interface and greatly enhanced stability. The buried interface is characterized using post-operando synchrotron X-ray depth profiling. This finding identifies hydrates as promising for improving the metal/electrolyte interfacial stability and suggests a general strategy for interface design.