The synergy of ferric surface anchoring and interior doping engineering enables anode with boosted potassium ion storage performances

Interfacial engineering , especially atomic substitution at the interface or inside the nanomaterials , is a promising strategy for fabricating high-performance electrode materials. Herein, an interfacial modification strategy was reported to develop cobaltous sulfide (CoS 2 ) nanomaterials with Fe clusters modified on their interface and Fe single atoms partially substituted Co atoms in CoS 2 (Fe-CFS), which were further wrapped by graphene networks, forming highly active Fe-CFS@graphene nanomaterials (Fe-CFS@C) with triple reaction interfaces . As the 1st interface, graphene can decrease their electrical resistance. At the 2nd interface, partial substitution of Co atoms in CoS 2 by Fe single atoms can reduce its band gap and boost the potassium ion (K + ) diffusion rate. At the 3rd interface, anchoring Fe clusters on the surface of CoS 2 results in the formation of Schottky junction and promotes the formation of built-in electric fields, which accelerates the K + insertion/extraction kinetics and depresses the dynamic polarization. Acting as anode for K + battery , Fe-CFS@C exhibits a high reversible capacity of 755.8 mA h g −1 at 0.05 A g −1 . Even at 10 A g −1 , it can maintain 178.3 mA h g −1 over 4000 cycles due to the greatly enhanced electrochemical reaction kinetics and effectively improved structural stability.