Enabling highly-efficient and stable potassium-ion storage by exposing atomic-dispersed super-coordinated antimony O₂Sb₁N₄ sites on N-doped carbon nanosheets

Carbonaceous anodes hold great promise for potassium-ion batteries (PIBs), however, their electrochemical performance is still unsatisfactory to meet practical requirements due to low capacities and sluggish insertion of large K⁺ ions. Herein, we showcase a previously unexplored design of high-load atomic antimony coordinated with four nitrogen and two oxygen atoms (i.e., O₂Sb₁N₄) in nitrogen-doped micropore carbon nanosheets (O-Sb-N SA@NC) for the PIB anode with markedly enhanced performance. Substantial in situ and ex situ experimental results along with theoretical computation explicitly reveal that the unique coordination environment of O₂Sb₁N₄ sites brings fascinating features for K⁺ storage including abundant K⁺ ion storage sites, reduced K⁺ diffusion barrier, enhanced capability for K⁺ ion adsorption/desorption, while O-Sb-N SA@NC effectively alleviates volume variation and agglomeration. Accordingly, the resultant anode has demonstrated large reversible capacities (593.3 mA h g⁻¹, 100 cycles at 0.1 A g⁻¹), high-rate capability, and extraordinary durability, outperforming most of the reported carbonaceous anodes. Notably, the assembled full cell exhibits exceptional rate capability and ultra-long lifespan (1200 cycles, 81% capacity retention at 5 A g⁻¹). Our work paves the way for constructing novel single atom materials on carbon with unique coordination structures for high-performance energy storage devices. © 2023 The Royal Society of Chemistry.