A Mott–Schottky Heterojunction with Strong Chemisorption and Fast Conversion Effects for Room‐Temperature Na–S Batteries

Abstract The practical application of the room‐temperature sodium–sulfur (RT Na–S) batteries is currently limited by low reversible capacity and serious capacity decay due to the sluggish reaction kinetics and shuttle effect. It is necessary to design a suitable sulfur host integrated with electrocatalysts to realize effective chemisorption and catalysis of sodium polysulfides (NaPSs). Herein, under the guidance of theoretical calculation, the Mott–Schottky heterojunction with a built‐in electric field composed of iron (Fe) and iron disulfide (FeS 2 ) components anchored on a porous carbon matrix (Fe/FeS 2 ‐PC) is designed and prepared. The enhanced chemisorption effect of Fe, the fast electrocatalytic effect of FeS 2 , and the fast transfer effect of the built‐in electric field within the Fe/FeS 2 heterojunction in the cathode of RT Na–S batteries work together to effectively improve the electrochemical performance. As a result, the Fe/FeS 2 ‐PC@S cathode exhibits high reversible capacity (815 mAh g −1 after 150 cycles at 0.2 A g −1 ) and excellent stability (516 mAh g −1 after 600 cycles at 5 A g −1 , with only 0.07% decay per cycle). The design of the Fe/FeS 2 heterojunction electrocatalyst provides a new strategy for the development of highly stable RT Na‐S batteries.