Altering Local Chemistry of Single‐Atom Coordination Boosts Bidirectional Polysulfide Conversion of Li–S Batteries

Abstract

Abstract Single‐atom catalysts affording multifarious typed metal centers and varied coordination numbers are extensively employed in Li−S realm to promote redox kinetics. Nevertheless, the modulation of coordination environment pertaining to local atomic composition to dictate the catalytic efficiency toward sulfur electrochemistry, has remains meaningful yet unexplored thus far. In this contribution, a new type of single‐atomic iron mediator with a designed FeN 3 P 1 coordination structure is reported to boost bidirectional polysulfide conversion in comparison with FeN 4 counterpart. Theoretical calculations imply that the substitution by one P atom at the first‐coordination shell of Fe center will be beneficial to strengthen adsorption toward sulfur species and reduce energy barrier for Li 2 S decomposition. The bidirectional electrocatalytic behavior for polysulfide conversion via FeN 3 P 1 mediator is confirmed by electrokinetic analysis. Consequently, the constructed Li−S battery achieves elongated lifespan with a capacity decay of 0.04% per cycle at 1.0 C and exhibits considerable capacity release of 6.2 mAh cm −2 even under a sulfur loading of 6.4 mg cm −2 . This strategy of local composition engineering offers a vivid example in probing the correlation between the definitive structure of single atoms and their catalytic performance in Li−S chemistry.