V2C MXene delivers excellent metallic properties and robust mechanical stability. However, its low capacity, easy volume expansion during charge/discharge and relatively short cycle life limits its further development. It is an effective strategy to build Van der Waals heterostructures that can shield the monolithic materials from defects and integrate the advantages of the monolithic materials. Herein, via a one-step hydrothermal method, a VO2@V2C heterostructure is successfully constructed by the controllable oxidation of V2C, which allows for shorter ion diffusion distances, faster ion transport and enhancement of hydrophilic properties of the material. The VO2@V2C heterostructures have incredible reversibility (440.9 mAh/g at 0.2 A/g), remarkable cycling stability (142.7 mAh/g at 1.0 A/g after 900 cycles) and superior-rate capacity (255.3 mAh/g at 6.0 A/g). Density functional theory (DFT) calculations revealed that VO2@V2C possesses excellent adsorption capacity for zinc ions and outstanding electrical conductivity. The heterogeneous interface between the two materials is conducive to the increase of the embedding sites of zinc ions, which promotes the homogeneous distribution and rapid diffusion of zinc ions in the materials, and consequently enhances the capacity and cycling reliability of the electrodes. It provides a new idea for the selection of cathode electrodes for aqueous zinc ion batteries (ZIBs) in present study.
Read full abstract