Dense homogeneous hetero‐interfacial coupling between amorphous Mo–N and crystalline Mo ₂ N for enhanced sodium‐ion storage

Abstract Optimizing the interfacial environments of electrodes has emerged as an effective strategy to improve their electrochemical properties. Amorphous/crystalline interfacial coupling can effectively utilize the advantages of amorphous materials to optimize the interfacial structure for efficient Na + storage. Herein, the dense homologous amorphous/crystalline heterointerfaces are in situ achieved in N‐doped carbon nanobundles via self‐polymerization and precise nitriding (Mo–N/Mo 2 N@C). The amorphous Mo–N rich in unsaturated vacancy defects provides abundant active sites with isotropic ion‐transport channels, and can effectively alleviate structural stress from crystalline Mo 2 N. Meanwhile, the conductive Mo 2 N can facilitate effective electron transfer, augmented further by the carbon encapsulation. Theoretical calculations reveal that the dense heterointerfaces can optimize the electronic structure and shift the d‐p orbital centers of Mo and N upward, thereby enhancing the adsorption and mobility of Na + , and ultimately improving the charge transport and storage efficiency of the electrode. The Mo–N/Mo 2 N@C as an anode delivers a 46.9% increase in reversible capacity over Mo 2 N@C, reaching 461.1 mAh·g –1 at 0.1 A·g –1 , along with improved rate capability and cycling stability, underlining its practical utility. These results suggest that the homologous interfacial coupling can boost the storage properties of nitrides, providing a valuable reference for improving the properties of electrodes with low theoretical capacities.