An Active Organic Polymer-Intercalated Vanadium Oxide Enabled Dual-Active High-Performance Cathode Materials for Aqueous Zinc-Ion Batteries

Vanadium oxides have garnered considerable interest as cathode materials in aqueous zinc-ion batteries owing to their high theoretical specific capacity. Nevertheless, the inherent instability of the layered structure and sluggish kinetics of vanadium oxide limit its broader application. Small-molecule intercalation has emerged as an effective strategy to enhance both structural stability and electrochemical performance. However, most intercalated molecules are electrochemically inactive, leading to a reduction in the overall capacity of the host vanadium oxide, thus compromising its performance. In this study, poly(catechol) (PCL), a polymer with active functional groups, is successfully intercalated into the layers of V2O5 (VO) via a one-step hydrothermal synthesis method. During this hydrothermal process, the phenolic hydroxyl groups of PCL are oxidized by hydrogen peroxide to carbonyl groups (C–OH → C═O), introducing active sites that can interact with Zn2+ ions, thus enhancing the overall electrochemical capacity of the composite material. Moreover, the intercalation of PCL not only increases the interlayer spacing of VO but also serves as a ″pillar″ that stabilizes the crystal structure, significantly improving Zn2+ ion diffusion kinetics and the overall zinc storage performance of the electrode material. As a result, the intercalated composite material VO-PCL exhibits good electrochemical performance, delivering a specific capacity of 466.4 mAh g–1 at 0.1 A g–1 and 221.9 mAh g–1 even at a high current density of 5 A g–1, with a capacity retention of 70.6% after 1,100 cycles. This study offers a valuable approach for utilizing organic polymers to intercalate inorganic materials, effectively contributing additional capacity and enhancing overall performance.