Facile synthesis of ultra-large V2O5 xerogel flakes and its application as a cathode material for aqueous Zn-ion batteries

Ultra-large V2O5 xerogel flakes were synthesized by a facile hydrothermal method with commercial V2O5 and H2O2 as raw materials. When evaluated as a cathode material for aqueous Zn-ion batteries in ZnSO4 electrolyte, the ultra-large V2O5 xerogel flakes exhibited superior electrochemical performance with a high specific capacity of 362 mA h g(-1) at 100 mA g(-1), a rate capacity of 160 mA h g(-1) at 1000 mA g(-1), and a capacity of 135 mA h g(-1) after 200 cycles (corresponding to a capacity-decay rate of 0.18 % per cycle). The apparent Zn2+ diffusion coefficient in the V2O5 xerogel flakes are determined in the order of 10(-10) cm(2) s(-1). Ex-situ XRD and SEM characterizations demonstrate that the V2O5 xerogel flakes well preserve the layered structure upon cycling; besides, Zn3V2O7(OH)(2)center dot 2H(2)O phase is detected on the surface of the electrode after cycling due to the dissolution V2O5 in the electrolyte. The superior performance of the sample can be due to the unique ultra-large 2D nanoflake structure which could offer continuous transport paths for both electrons and Zn2+ in the whole flakes and shorten the Zn2+ diffusion length in the direction perpendicular to the flakes.

Automated summary

Ultra-large V2O5 xerogel flakes were synthesized and used as cathode materials for aqueous Zn-ion batteries, exhibiting superior performance possibly due to its unique 2D nanoflake structure that offers continuous transport paths and shortens Zn2+ diffusion length.