Spatial confinement and interfacial electron regulation in N-doped carbon-encapsulated CoTe₂/Co_1.11Te₂...

The strategic design of robust and high-performance cobalt telluride anodes is indispensable for advanced sodium-ion storage. However, the significant volume variation, limited intrinsic conductivity, and inferior structural stability impede their further advancement. To overcome these obstacles, the heterostructured CoTe₂/Co_1.11Te₂ nanoparticles were in situ confined within the thin N-doped carbon layer (CoTe₂-Co_1.11Te₂@NC) through plasma engineering and tellurization process. This carbon-confined architecture provides abundant electron/ion transport channels and stable structural buffering, ensuring high nanoparticle dispersibility, improving conductivity, and alleviating volumetric changes. Additionally, the heterogeneous CoTe₂/Co_1.11Te₂ interface enables electronic structure regulation, accelerating charge transfer and enhancing electrical conductivity and Na⁺ adsorption abilities as demonstrated by theoretical calculations and electrochemical experiments. The synergistic effect of spatial confinement engineering and interface modulation endows CoTe₂-Co_1.11Te₂@NC with impressive capacity performance of 322.4 mAh g^-1 after 200 cycles at 0.2 A g^-1, exceptional rate capability of 155.3 mAh g^-1 at 10.0 A g^-1, and ultralong cycling life of 181.1 mAh g^-1 after 3000 cycles even at 5.0 A g^-1. Furthermore, the CoTe₂-Co_1.11Te₂@NC//Na₃V₂(PO₄)₃ full cell demonstrates the outstanding properties and promising practical feasibility. Moreover, a highly reversible Na⁺ intercalation-conversion mechanism is confirmed by multiple ex-situ characterizations. This work offers valuable perspectives for designing durable and efficient electrochemical storage systems through confinement strategy and homologous heterostructure construction.