Optimization strategies of cathode materials for room-temperature sodium–sulfur batteries

Room-temperature sodium–sulfur (RT Na–S) batteries are highly competitive energy storage devices due to their abundant natural reserves, low cost, and excellent theoretical energy density. S cathode, as an important component of RT Na–S, has challenges during charging/discharging processes, including large fluctuations in the volume of the S species during sodiation/desodiation, severe shuttle effect, and sluggish reaction kinetics, which greatly limit the development and practical application of RT Na–S. To solve these problems, the researchers designed a variety of reactors with different morphologies to inhibit the shuttling of sodium polysulfides (NaPSs) through van der Waals forces and mitigate the volume change during charging/discharging processes. It was found that the addition of suitable catalyst materials could increase the ion/electron transport rate of S cathode and improve the electrochemical performance through adsorption-catalysis synergy. Herein, a comprehensive review is conducted for the improvement work of RT Na–S battery cathode in the last decade, including reactor design, catalyst design, and S cathode design. Finally, the major challenges facing the development of cathode materials for RT Na–S batteries are summarized, and their future directions are outlined.