Rational construction of Ag@MIL-88B(V)-derived hierarchical porous Ag-V2O5 heterostructures with enhanced diffusion kinetics and cycling stability for aqueous zinc-ion batteries

With the advantages of the multiple oxidation states and highly open crystal structures, vanadium-based composites have been considered as the promising cathode materials for aqueous zinc-ion batteries (ZIBs). However, the inherent inferior electrical conductivity, low specific surface area, and sluggish Zn2+ diffusion kinetics of the traditional vanadium-based oxides have greatly impeded their development. Herein, a novel hierarchical porous spindle-shaped Ag-V2O5 with unique heterostructures was rationally designed via a simple MOF-assisted synthetic method and applied as stable cathode for aqueous ZIBs. The high specific surface area and hierarchically porous superstructures endowed Ag-V2O5 with sufficient electrochemical active sites and shortened the diffusion pathways of Zn2+, which was beneficial to accelerate the reversible transport of Zn2+ and deliver a high specific capacity (426 mA h g−1 at 0.1 A g−1 and 96.5% capacity retention after 100 cycles). Meanwhile, the self-built-in electric fields at the heterointerface of Ag-V2O5 electrode could strengthen the synergistic coupling interaction between Ag and V2O5, which can effectively enhance the electric conductivity and maintain the structural integrity, resulting in superb rate capability (326.1 mA h g−1 at 5.0 A g−1) and remarkable cycling stability (89.7% capacity retention after 2000 cycles at 5.0 A g−1). Moreover, the reversible Zn2+ storage mechanism was further investigated and elucidated by kinetics analysis and DFT calculations.