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

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.