Nitrogen-coordinated antimony atom anchored on carbon matrix as efficient active sites to enhance sodium/potassium ion storage.

Carbon-based anode materials have become a research hotspot for alkali metal ion batteries. Crucially, the electrochemical performance of carbon materials must be improved by appropriate means such as micro-nano structure design and atomic doping. Herein, antimony doped hard carbon materials are prepared by anchoring Sb atoms on nitrogen-doped carbon (SbNC). The coordination of non-metal atoms can better disperse Sb atoms on the carbon matrix, and the synergistic effect between Sb atoms, coordinated non-metal atoms, and hard carbon matrix endows SbNC anode with good electrochemical performance. When used in sodium-ion half-cells, the SbNC anode showed high rate capacity of 109 mAh g at 20 A g and good cycling performance (254 mAh g at 1 A g after 2000 cycles). In addition, when used in potassium-ion half-cells, the SbNC anode exhibited initial charge capacity of 382 mAh g at 0.1 A g and rate capacity of 152 mAh g at 5 A g. This research shows that compared with ordinary nitrogen doping, Sb-N coordination active sites on carbon matrix can provide much more adsorption capacity, improve ion filling and diffusion properties as well as enhance the kinetics of electrochemical reaction for the sodium/potassium storage.