K+-regulated vanadium oxide heterostructure enables high-performance aqueous zinc-ion batteries†

The low reaction kinetics and unstable structure of vanadium-based cathodes often lead to the poor capacity and stability of aqueous zinc-ion batteries (AZIBs). In this study, K⁺ was introduced to regulate vanadium oxide, and novel triple-phase heterostructures were obtained via a solid reaction process. Owing to the large interlayer spacing of potassium vanadate and the sufficient phase boundary in heterointerfaces, Zn²⁺-transport ability in the composites could be effectively increased, and more Zn²⁺-storage sites could be provided in the heterointerface. The cathode materials illustrated an excellent specific capacity of 460.6 mA h g⁻¹ at 0.2 A g⁻¹, comparative rate performance and a capacity retention of 90.7% after 2500 cycles at 3 A g⁻¹. Finally, Zn²⁺- and proton H⁺-storage mechanisms were investigated using ex situ XRD, SEM and XPS analyses. This study proposes a new strategy for the development of high-performance AZIBs.