Unveiling the Effects of Cr Single Atoms with Controllable Configurations on Solid Electrolyte Interphase and Storage Mechanism of Sodium Ions

Abstract Single atomic metal (SAM) doping is reported as an effective strategy to promote the electrochemical property of carbon‐based anode materials for high‐power sodium‐ion batteries (SIBs). However, the effects of SAM with different configurations on solid electrolyte interphase (SEI) and energy storage mechanism of Na⁺ are not revealed. Herein, Cr single atoms (CrSAs) are reported with controllable configurations (Cr–N₄ or Cr–N₂) implanted on the N, P co‐doped carbon (NPC) anode materials (denoted as CrN₄SAs/NPC or CrN₂SAs/NPC). The CrN₄SAs/NPC anode displays a high specific capacity (318.2 mAh g⁻¹ at 0.05 A g⁻¹) and outstanding rate performance (145.1 mAh g⁻¹ at 5 A g⁻¹), better than those of CrN₂SAs/NPC and NPC. The superiority is originated from the difference of SEI and the energy storage mechanism of sodium ions during electrochemical process, which are unveiled through ex situ characterization and theoretical calculation. The full cell assembled with CrN₄SAs/NPC anode and Na₃V₂(PO₄)₂F₃@C cathode displays a high energy density at a high power density.