Advances and challenges in tuning the reversibility & cyclability of room temperature sodium-sulfur and potassium-sulfur batteries with catalytic materials

Abstract

The high theoretical energy density of room temperature sodium-sulfur and potassium-sulfur batteries (Na-S; 1,274 Wh kg-1, K-S; 914 Wh kg-1; based on the mass of sulfur) due to the multi-electron transfer associated with the unique conversion chemistry of S and the natural abundance of Na, K, and S raw materials make them ideal candidates for large-scale energy storage applications beyond Li batteries. However, achieving good reversibility, cyclability, and active material utilization in Na-S and K-S batteries demands alleviation of the complex polysulfide dissolution and the shuttle phenomena during cycling. Rational employment of catalytic materials is beneficial to address these issues by facilitating effective polysulfide transformation and thereby accelerating the sluggish reaction kinetics. This review focuses on the roles and evolution of catalytic materials in polysulfide adsorption, catalytic conversion, and redox mediation in facilitating high-performing Na-S and K-S batteries. Specifically, the advances in tuning the reversibility and cyclability of NaS and K-S batteries strategically with catalytic material-incorporated S-host cathodes, separators, and interlayers and the interaction of various catalytic materials with the polysulfide species are discussed in the light of advanced characterization techniques. Lastly, the challenges and the plausible strategies for future research are elucidated.