In-Situ Construction of V₂O₅ Nanosheet/Nitrogen-Doped Carbon Nanosheet Heterostructures with Interfacial C─O Bridging Bonds as the Cathode Material for Zn Ion Batteries

Layered oxides are widely used as the electrode materials for metal ion batteries. However, for large radius size ions, such as Zn²⁺ and Al³⁺, the tightly stacked layers and poor electrical conductivity of layered oxides result in restricted number of active sites and sluggish reaction kinetics. In this work, a facile in-situ construction strategy is provided to synthesize layered oxide nanosheets/nitrogen-doped carbon nanosheet (NC) heterostructure, which shows larger interlayer spacing and better electrical conductivity than the layered oxides. As a result, the Zn²⁺ ion diffusion inside the interlayer gallery is greatly enhanced and the storage sites inside the gallery can be better used. Meanwhile, the NC layers and oxide nanosheets are bridged by the C─O bonds to form a stable structure, which contributes to a better cycling stability than the pure layered oxides. The optimal V₂O₅@NC-400 cathode shows a capacity of 467 mA h g⁻¹ at 0.1 A g⁻¹ for 300 cycles, and long-term cyclic stability of 4000 cycles at 5 A g⁻¹ with a capacity retention of 92%. All these performance parameters are among the best for vanadium oxide-based cathode materials.