Unlocking the Role of Carbon Microstructure in MOF ‐Mediated Interfacial Engineering for Fast‐Charging Sodium‐Ion Batteries

The performance of hard carbon anodes in sodium‐ion batteries is restricted by the inherent trade‐off between rate capability and capacity due to uncoordinated ion‐electron transport. This research indicates that the microstructure of the carbon host crucially determines the interfacial reconstruction behavior and electrochemical outcome of MOF modification. For porous cellulose‐derived carbon, the integration of MOF induces a continuous composite interface, enhancing the Na + diffusion coefficient by an order of magnitude below 0.1 V (reaching 10 −9 cm 2 s −1 ), and yielding a high reversible capacity of 667.2 mAh g −1 with 79% capacity retention. In contrast, on commercial hard carbon with a higher degree of graphitization, MOF forms a discontinuous physical coating that obstructs intrinsic ion pathways, restricting rate performance of hard carbon despite the improvement in its cycling stability. In‐situ EIS and distribution of relaxation time analyses disclose lower charge‐transfer resistance and optimized SEI evolution in MOF@cellulose‐derived carbon, facilitating efficient ion‐electron dual transport. The full cell utilizing MOF@cellulose‐derived carbon attains a high energy density of 172.8 Wh kg −1 at a power density of 2065 W kg −1 . This work offers mechanistic insights into the correlations among carbon microstructure, interface, and performance, guiding the rational anodes design of high‐power and high‐energy density sodium‐ion batteries.