Abstract:

Transition metal vanadates, as an advantageous anode material for lithium-ion batteries, currently have bottlenecks such as unsatisfied conductivity and cycle stability caused by drastic volume changes during charging and discharging. In this study, NiCo₂V₂O₈@TiO₂@NC material with a multi-level composite core-shell structure was prepared using a step-by-step coating strategy to improve this defect. Initially, yolk-shell structured NiCo₂V₂O₈ nanospheres were synthesized as the precursor through hydrothermal synthesis and ion exchange methods. Subsequently, a robust TiO₂ layer and a nitrogen-doped carbon (NC) network structure were coated on the surface, resulting in formation of a hierarchical mesoporous nanostructure. The specific yolk-shell nanosphere structure provides abundant channels for Li⁺ transport in NiCo₂V₂O₈, a promising electrochemical active material. Further coating with a TiO₂ layer not only enhances the stability and durability of the material, but also offers additional electrochemical active sites. Moreover, introduction of the nitrogen-doped carbon network structure not only improves conductivity of the ordered multi-level core-shell NiCo₂V₂O₈@TiO₂@NC material but also facilitates rapid electron transport, further optimizing its electrochemical performance. When lithium-ion battery anode materials were prepared under optimal conditions, the obtained cell exhibited an initial specific capacity of 1422.0 mAh∙g^-1, which remained 1011.9 mAh∙g^-1 after 500 cycles, corresponding to a specific capacity retention rate of 71.2%. This material demonstrates high specific capacity, good rate performance, and excellent cycle stability, displaying promising prospective for a wide range of applications in energy storage devices.

Key words: core-shell structure, transition metal oxide, lithium-ion battery, electrochemical performance