Ultrathin Electron-Delocalized Conductive Coating for Enhanced Cathodic Kinetics of Durable Zinc-Ion Batteries

Abstract

Vanadium oxides have been widely used as cathode materials for aqueous zinc ion batteries (ZIBs) owing to their distinctive layered structure and high theoretical capacity. However, their structural instability, poor conductivity, and sluggish ion migration kinetics severely limit their practical applications. Herein, an ultrathin electron-delocalized conductive polypyrrole coating was constructed on V₂O₅ (denoted as V-VO@CP) under a unique vapor-thermal environment. The in situ polymerization of pyrrole vapor improves the π-electron delocalization of the formed polypyrrole coating, which enhances the electron/ion transfer kinetics of the V-VO@CP cathode. Furthermore, the ultrathin even conducting coating (thickness of 11.57 nm) enhances the interfacial electronic conductivity of the V₂O₅ host and mitigates vanadium dissolution, thus achieving the stable cycling performance. The ZIB with the V-VO@CP cathode delivers a maximum discharge capacity of 383 mAh g^–1 at 0.5 A g^–1 and 262 mAh g^–1 at 10 A g^–1 with 80% capacity retention after 3000 cycles. These results verify the feasibility of a vapor-thermal environment for developing an efficient and scalable polymer coating of advanced cathode materials.