High-Rate Na-Ion Storage Enabled by Metal-Nitrogen-Carbon (M-N-C) Charge Transfer Bridges

Due to the large ionic radius of sodium ions, which leads to inferior electrochemical kinetics and rate performance, the applications of sodium-ion batteries are limited. In this study, nickel sulfide nanoparticles are uniformly dispersed within nitrogen- and sulfur-co-doped carbon nanosheets (Ni/NSC) via a unique synthetic method, facilitated by strong nickel-nitrogen bonds (Ni─N bonds). The resultant Ni─N bonds provide a synergistic effect, which not only enhances charge transfer but also suppresses volume changes, thereby ensuring structural stability and high-efficiency energy storage. Meanwhile, the composite material integrates the advantages of both components: the thin carbon nanosheets containing dopants enhance the diffusion pathways for sodium ions, while the integrated NiS nanocrystals form an electronic transport network, ensuring stability during charge-discharge cycling. As a result, the composite material exhibits high reversible capacity and significant rate performance at high current densities, offering a promising strategy for the development of high-rate electrode materials.