Argyrodite Superionic Conductors Fabricated from Metathesis-Derived Li₂S

Lithium sulfide (Li2S) is both a high-capacity cathode and the critical component in sulfide-based lithium-ion solid-state electrolytes. Conventionally produced by carbothermal or H2S reduction, its high cost constrains development of the next-generation batteries that employ it. Here, we introduce production of Li2S though room-temperature (RT) metathesis using LiCl and technical grade Na2S·xH2O that was either dehydrated or further purified through hydrogen reduction. Li6PS5Cl argyrodites derived from metathesis Li2S display high ionic conductivity (>4 mS cm–1 at RT), exceeding that of the commercial Li2S control. Metathesis offers an economical and energy efficient route for the scalable production of this critical material.