Layered porous Mn0.18V2O5@C with manganese and carbon provided by a metal–organic framework precursor as a cathode material for aqueous zinc-ion batteries

Abstract

At present, vanadium-based cathodes for aqueous zinc-ion batteries (AZIBs) are limited by their slow reaction kinetics, poor electrical conductivity, and low capacity retention. To overcome these problems, here, we design a layered porous Mn_0.18V₂O₅@C as the cathode material for AZIBs using a manganese-containing metal–organic framework as a template through a simple solvothermal method. Such an electrode delivers an excellent specific capacity (380 mA h g⁻¹ at 0.1 A g⁻¹) accompanied by superior cycling stability (about 85% capacity retention for 2000 cycles at 6 A g⁻¹). The excellent electrochemical performance of Mn_0.18V₂O₅@C is ascribed to the improved interface activity including smooth zinc ion transport, abundant ion reaction active sites and accelerated charge transfer resulting from the coordination of the porous structure, doped conductive carbon, and the stable channel structure derived from the pillar effect of doping manganese ions, preventing a premature collapse of the electrode structure. It is also revealed by structural evolution analysis that the residual zinc ions also combine with the original Mn_0.18V₂O₅ to form a Zn_xMn_yV₂O₅ phase, which serves as an additional structural pillar and in the meantime, also participates in the following cycles. These favorable electrochemical results suggest that Mn_0.18V₂O₅@C is a suitable cathode material for AZIBs.