Experimental Validation of Density Functional Theory Predictions on Structural Water Impact in Vanadium Oxide Cathodes for Zinc-Ion Batteries

Abstract

This study combines experimental methods with density flooding theory (DFT) calculations to investigate the enhancement of the electrochemical performance of vanadium oxide cathodes for aqueous zinc ion batteries (AZIBs) through strategic water content management. DFT predictions indicated that a moderate presence of structural water optimizes electrical conductivity and facilitates zinc ion diffusion. These theoretical insights are empirically validated by synthesizing AlVO-1.6 H2O using a hydrothermal method, which exhibited superior electrochemical properties. This material demonstrated an impressive initial capacity of 316 mAh g⁻¹ at 0.2 A g⁻¹, with robust capacity retention after extended cycling. Remarkably, even at an elevated current density of 10 A g⁻¹, it sustains a capacity of 161.6 mAh g⁻¹, while maintaining a capacity retention of 97.6% over 2000 cycles. The results confirm that adjusting the structural water content in vanadium oxides significantly boosts their electrochemical capabilities, aligning experimental outcomes with computational forecasts and showcasing a novel approach for developing high-performance cathodes in energy storage technologies.