Single Atomic Cu-C₃ Sites Catalyzed Interfacial Chemistry in Bi@C for Ultra-Stable and Ultrafast Sodium-Ion Batteries

Regulating interfacial chemistry at electrode-electrolyte interface by designing catalytic electrode material is crucial and challenging for optimizing battery performance. Herein, a novel single atom Cu regulated Bi@C with Cu-C₃ site (Bi@SA Cu-C) have been designed via the simple pyrolysis of metal-organic framework. Experimental investigations and theoretical calculations indicate the Cu-C₃ sites accelerate the dissociation of P-F and C-O bonds in NaPF₆-ether-based electrolyte and catalyze the formation of inorganic-rich and powerful solid electrolyte interphase. In addition, the Cu-C₃ sites with delocalized electron around Cu trigger an uneven charge distribution and induce an in-plane local electric field, which facilitates the adsorption of Na⁺ and reduces the Na⁺ migration energy barrier. Consequently, the obtained Bi@SA Cu-C achieves a state-of-the-art reversible capacity, ultrahigh rate capability, and long-term cycling durability. The as-constructed full cell delivers a high capacity of 351 mAh g^-1 corresponding to an energy density of 265 Wh kg^-1. This work provides a new strategy to realize high-efficient sodium ion storage for alloy-based anode through constructing single-atom modulator integrated catalysis and promotion effect into one entity.