Ni‐Single Atoms Modification Enabled Kinetics Enhanced and Ultra‐Stable Hard Carbon Anode for Sodium‐Ion Batteries

Abstract

Hard carbon with randomly oriented interlayers is the most promising candidate for the anode of commercial sodium‐ion batteries (SIBs). Nevertheless, its sluggish sodium storage kinetics and unsatisfactory cycling stability are bottlenecks to its implementation. Herein, a metal‐single atom modification strategy is proposed to construct a Ni‐single atoms modified N, P co‐doped hard carbon (Ni‐NPC) with a Ni content of ≈5.65 wt%. As an anode for SIBs, Ni‐NPC exhibits far superior initial Coulombic efficiency, reversible specific capacity, rate capability, and cycling stability to N, P co‐doped hard carbon. Combining in situ EIS and ex‐situ XPS,this study reveals that Ni‐single atoms modulate the composition of the solid electrolyte interface layer, thereby improving the cycling stability of Ni‐NPC. Theoretical calculation and kinetics analysis suggest that Ni‐single atoms are the promoters of the diffusion of Na+. Furthermore, with the aid of systematic in situ characterizations, the structural evolution of Ni‐NPC at different sodium storage stages is identified. This work proposes a potential strategy for simultaneously improving the sodium storage kinetics and cycling stability of hard carbon anodes, and elucidates the improvement mechanism of this strategy.