Enhanced electrochemical performance of pre-treated V2O5 as cathode material in aqueous Zinc-ion batteries

The evolution of cathode materials is crucial for the large-scale manufacturing of aqueous zinc-ion batteries. Vanadium-based materials possess large interlayer distances and thus allow for easy intercalation/deintercalation processes of zinc ions. However, commercially available V2O5 is seldom used directly as cathode materials for aqueous zinc ion batteries because of low activity and more side reactions. Here, we have outlined a methodology to to enhance its reactivity and prevent the side reaction effectively. The pre-treated V2O5 (V2O5-P) was carried out through a combination of water bath treatment at a temperature of 65 degrees C and freeze-drying, which showed expanded layer spacing and increased density of active sites. The structural variations of V2O5 during pretreatment were analyzed using various test methods, and the structural evolution in cathode material and energy storage mechanism during charge/discharge was also investigated by in-situ Electrochemical Impedance Spectroscopy. The V2O5-P material showed almost no capacity degradation during 200 charge/ discharge cycles (0.5 A g- 1 ) with a Coulombic efficiency consistently exceeding 99.98 %. After 5000 cycles (2 A g- 1 ), V2O5-P maintained 70 % specific capacity with a Coulombic efficiency of more than 99.5 %. As a result, this work presented an easy-to-use method for commercialized materials applied to energy storage on a larger scale.