Electrolyte strategies for practically viable all-solid-state lithium-sulfur batteries

All-solid-state lithium-sulfur batteries are a promising platform due to their high gravimetric energy density and enhanced safety. However, they face numerous challenges that currently obstruct commercial adoption. The key to overcoming these challenges lies in the rational selection and targeted development of solid-state electrolytes, where different materials classes present distinct trade-offs between performance and practicality. We assert that sulfide electrolytes offer the best compatibility with the cathode and anode requirements for practical sulfur cells, with halides and borohydrides also showing potential for use in the cathode with further development. We provide cell-level target parameters to ensure that the field moves consistently towards commercial relevance. Looking forward, we call for the adoption of the chlorinated argyrodite with a composition range of Li6-xPS5-xCl1+x (x = 0 − 0.5) as a standardized solid-state electrolyte to enable rigorous benchmarking across the field and accelerate battery development. Solid-state electrolytes are key to the successful implementation of high-performance all-solid-state lithium-sulfur batteries. This Review discusses the different classes of materials that can be used for electrolytes, focusing on sulfides, halides, oxides, and borohydrides.