K-doped V2O5 derived from V-MOF precursor as high-performance cathode for aqueous zinc-ion batteries

Abstract

The safety and low toxicity of aqueous zinc-ion batteries (ZIBs) are piqueing intense scientific interest. Slow reaction kinetics and substantial structural degradation of the cathode materials, however, prevent the creation of ZIBs. As a better cathode for ZIBs, tunnel-structured V2O5 hierarchical with a high preintercalated K cation content (K-V2O5) are proposed here. The K-V2O5 are specifically made using a self-sacrificial template approach that also involves hydrothermal intercalation in a neutral solvent and phase change during annealing. A subsequent H+ and Zn2+ intercalation procedure at various voltage platforms is clarified when tested as cathodes for ZIBs. Prior to the subsequent insertion of Zn2+ into V2O5, the water-solvated H+ first enters tunnel cavities, which partially transforms the V2O5 phase from a tunnel-type structure to a layered-type structure. The pre-intercalated K cations with a high content that act as pillars in the layered-type matrix stabilize the layered structures and widen the migration channels for Zn2+, which can aid in the diffusion of Zn2+ in the V2O5 cathodes.