Edge Coordination of Ni Single Atoms on Hard Carbon Promotes the Potassium Storage and Reversibility

Abstract Hard carbon is the most promising anode for potassium‐ion batteries (PIBs) due to its low cost and abundance, but its limited storage capacity remains a major challenge. Herein, edge coordination of metal single atoms is proved to be an effective strategy for promoting potassium storage in hard carbon for the first time, taking B, N co‐doped hard carbon nanotubes anchored by edge Ni‐N 4 ‐B atomic sites (Ni@BNHC) as an example. It is revealed that edge Ni‐N 4 ‐B can provide active sites for interlayer adsorption of K + and that Ni atoms can facilitate the reversibility of K + storage on N and B atoms. Furthermore, an unprecedentedly reversible K + storage capacity of 694 mAh g −1 at 0.05 A g −1 is realized by introducing commercial carbon nanotubes. This work provides a new perspective for the application of single‐atom engineering and the design of high‐performance carbon anodes for PIBs.