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 Zn 2+ diffusion kinetics of the traditional vanadium-based oxides have greatly impeded their development. Herein, a novel hierarchical porous spindle-shaped Ag-V 2 O 5 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-V 2 O 5 with sufficient electrochemical active sites and shortened the diffusion pathways of Zn 2+ , which was beneficial to accelerate the reversible transport of Zn 2+ 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-V 2 O 5 electrode could strengthen the synergistic coupling interaction between Ag and V 2 O 5 , 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 Zn 2+ storage mechanism was further investigated and elucidated by kinetics analysis and DFT calculations.