Unlocking the Future of Room Temperature Sodium–Sulfur Batteries: Cathode Innovations, Challenges, and Future Prospects

The rising cost, safety issues, and limited resources of lithium-ion batteries have accelerated the search for alternative energy storage technologies. Room-temperature sodium-sulfur (RT Na-S) batteries are gaining attention due to their low cost, abundant raw materials, environmental friendliness, and inherent safety, making them a promising option for grid-scale storage and electric mobility. Despite these advantages, the commercialization of these technologies still faces significant challenges. The insulating nature of sulfur and its byproducts promotes the formation and dissolution of sodium polysulfides, triggering the shuttle effect and causing rapid capacity fading. Additionally, the substantial volume change of the cathode during cycling compromises its structural stability and reduces cycle life. In this review, recent developments and persisting challenges in cathode materials are highlighted, which remain the central bottleneck to achieving long-term stability and high performance. Current strategies are categorized into three approaches: physical inhibition, chemical inhibition, and electrocatalytic inhibition, each distinctly addressing polysulfide management. Advances in in situ and operando characterizations uncover reaction mechanisms, providing critical guidance for rational electrode engineering. Finally, the state-of-the-art cathode innovations, key limitations, and proposed future research directions are included to unlock the full potential of RT Na-S batteries in large-scale energy storage systems.