Capacity-enhanced and kinetic-expedited zinc-ion storage ability in a ZnVO/VO cathode enabled by heterostructural design.

Heterostructured double-phase composites are promising electrode candidates for high-performance secondary metal batteries due to their superior capacity and ion transfer kinetics compared with the pristine phase. Herein, a ZnVO/VO (ZVO/VO) heterostructure with abundant phase boundaries was designed as the cathode for aqueous zinc-ion batteries (ZIBs). The preparation method is based on a solid pre-intercalation approach, and the Zn content in the ZVO/VO heterostructure can be precisely controlled. The electrochemical performance of ZVO/VO containing different amounts of Zn, pristine ZVO, and VO phases was compared. ZVO/VO showed superior capacity and cycling stability compared to pristine ZVO and VO. The ZVO/VO heterostructure showed a capacity of 328.4 mA h g at 0.3 A g after 200 cycles. The long-term cycling performance of ZVO/VO was evaluated at 3 A g, and it delivered a capacity retention of 90.5% after 1000 cycles. The ion storage mechanism of the ZVO/VO electrode was analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). This work provides a simple strategy for designing vanadium-based heterostructure composites as advanced cathodes for ZIBs.