Nb atom-mediated activation and strong homogeneous coupling of amorphous Mo-N clusters boosting sodium-ion storage

Abstract

Specific active sites and relatively restricted ion transport paths in crystalline electrodes greatly limit the Na⁺ storage properties. To effectively utilize the storage potential of these electrodes, integrating atomic mediation with strong homogeneous coupling in amorphous clusters, this study synthesizes N-doped carbon nanosheet-spheres with Nb atom-activated amorphous Mo-N clusters (Nb/Mo-N@NC). The clusters exhibit high storage capacity and transport efficiency for Na⁺ with abundant N-vacancies, isotropic ion transport channels, and efficient atomic utilization. Theoretical calculations confirm that the mediation of unoccupied orbital-rich Nb atoms can induce the electronic reconfiguration and d-p orbital hybridization of the clusters, and the strong homogeneous coupling can enhance the Na⁺ adsorption energy and enrich the electrochemically active sites, thereby further boosting Na⁺ storage of the clusters. Additionally, the in-situ carbon composite strongly guarantees the structural stability and conductivity of the clusters. Benefiting from these advantages, Nb/Mo-N@NC exhibits outstanding Na⁺ storage performance as an anode: achieving 540.9 mAh/g reversible capacity at 0.1 A/g and retaining 264.1 mAh/g after 5000 cycles at 10.0 A/g, while showcasing outstanding practical application potential. These results indicate that the atom-mediating and homogeneous coupling of amorphous clusters contributes to Na⁺ storage, shedding important light on the design of high-performance anodes.