Coupled CoN 4 Single‐Atom and Co 4 Clusters Catalysts in Bi Anodes for Ultrafast and Ultralong Sodium Storage

ABSTRACT Metal single‐atom catalysts can catalyze electrolyte decomposition to regulate solid electrolyte interphase (SEI) formation, yet the intrinsic reaction pathways at isolated active sites hinder targeted SEI composition design. Herein, we innovatively construct a Bi@NC anode decorated with CoN 4 single sites and Co 4 clusters via a thermodynamically driven phase separation mechanism. This dual‐site design overcomes the limitations of isolated CoN 4 , enabling the formation of an inorganic‐rich and multifunctional gradient SEI that ensures high structural flexibility, rapid Na + diffusion, and effective dendrite suppression. Specifically, Co 4 clusters preferentially catalyze organic electrolyte decomposition to favor the formation of inorganic Na 2 CO 3 , while simultaneously upshifting the Co d ‐band centre of CoN 4 to enhance PF 6 − adsorption and P–F bond (NaPF 6 ) cleavage. The electronic synergy between CoN 4 and Co 4 clusters further induces local electron delocalization, optimizing the reaction microenvironment. As a result, the anode delivers an exceptional rate capability of 325 mAh g −1 at 90 A g −1 , enabling full charging within 13 s. Remarkably, it achieves ultralong cycling stability with a capacity of 373 mAh g −1 after 20 000 cycles, maintaining 96.4% of its initial capacity with a decay rate of only 0.00018% per cycle. This work provides a new paradigm for designing durable, fast‐charging anodes through interfacial catalytic chemistry.