Preparation and Electrochemical Performance of N-Doped H_xV₂O₅/CeVO₄ Composite Films as Stable Cathodes for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (AZIBs) have attracted considerable attention due to their low cost, high safety, and environmental friendliness, however, the structural problems triggered by the repeated insertion and extraction of Zn²⁺ in vanadium-based cathode materials remain a key challenge restricting their development. In this work, N-doped H_xV₂O₅/CeVO₄ composite films were successfully prepared on indium-tin-oxide (ITO) conductive glass by low-temperature liquid-phase deposition combined with an annealing process. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy were employed to systematically characterize the differences in crystal structure, morphological evolution, and microscopic properties of the thin-film electrodes at various annealing temperatures. In order to inhibit the dissolution of the electrode during the reaction process, paperboard was introduced as a physical barrier layer in the electrochemical tests, and the galvanostatic charge/discharge (GCD) test results showed that the paperboard system could effectively improve the cycling stability. Among them, the composite film annealed at 450 °C showed the best performance: 83.9% (223.94 mA h m^-2) capacity retention after 100 cycles at 100 mA m^-2 current density, significantly better than that of the 500 °C sample. XRD and XPS analyses show that the tunnel structure of H_xV₂O₅ provides high-capacity storage sites. At the same time, the tetragonal zirconium skeleton of CeVO₄ synergistically enhances the stability of the material by suppressing the structural collapse caused by Zn²⁺ insertion/extraction. Nitrogen doping further enlarges the H_xV₂O₅ lattice spacing ((200) crystallite spacing increased from the standard 0.576 to 0.607 nm), optimizing the ion diffusion kinetics. This study provides a path for developing highly stable vanadium-based composite electrodes through a synergistic strategy of atomic doping and composite structure design.