Development of Materials for All Solid‐State Sodium‐Sulfur Batteries: Review and Prospects

Abstract The increasing global energy demand has accelerated the development of cost‐effective energy storage technologies. Among various alternatives to conventional lithium‐ion batteries, sodium‐sulfur (Na–S) all‐solid‐state batteries (ASSBs) have emerged as a promising solution due to the abundance and low cost of sodium and sulfur. While traditional high‐temperature Na–S batteries offer high energy densities, their elevated operational temperatures (> 300 °C) pose significant safety and cost challenges. To mitigate these issues, low‐temperature (LT) Na–S ASSBs (operating below 80 °C) have gained attention for their improved safety, reduced maintenance costs, and high theoretical capacity. However, they still face critical obstacles such as poor electrode–electrolyte contact and sluggish interfacial kinetics. This review focuses on recent advancements in LT Na–S battery technology, particularly those employing solid‐state electrolytes. A comprehensive discussion is provided on the critical design principles for cathodes, anodes, and electrolytes, highlighting the progress, challenges, and opportunities associated with each component. Finally, the perspective on future research directions necessary to realize practical, high‐performance LT Na–S ASSBs for large‐scale energy storage applications is presented.