Enhanced Electrochemical Performance of Aqueous Zn-Ion Batteries Based on Na2V6O16∙2H2O Cathodes: Insights from DFT and Synchrotron X-ray Analysis

Abstract

Aqueous zinc-ion batteries (AZIBs) have attracted significant attention because of their advantages such as high volumetric energy density, cost-effectiveness, and outstanding safety using an aqueous electrolyte. However, the main challenge in AZIBs originates from structural degradation at the cathode during repetitive charge/discharge cycles, which results in poor electrochemical performance. In this study, we present a novel material strategy for enhancing the electrochemical performance of AZIBs using a reliable cathode material, Na2V6O16∙2H2O (NaVO), produced via the pre-intercalation of Na ions into V2O5 through one-step sonochemical synthesis. NaVO enhances the structural stability and electrochemical performance of AZIBs. Therefore, a NaVO cathode paired with a Zn anode (NaVO//Zn) exhibits a capacity of 126.3 mAh g–1 at a high current density of 10 A g–1 and maintains a capacity retention rate of 91.8% after 10,000 cycles, thereby demonstrating exceptional long-term cycling stability. Density functional theory calculations (DFT) combined with in situ synchrotron-based X-ray techniques provide scientific insights into the underlying mechanism of the enhanced electrochemical performance related to the structural stability of NaVO.