Al³⁺ Introduction Hydrated Vanadium Oxide Induced High Performance for Aqueous Zinc-Ion Batteries

Aqueous zinc ion batteries are a promising alternative secondary battery technology due to their excellent safety and environmental friendliness. Vanadium-based compounds as a highly promising class of cathode materials still suffer from structural collapse and slow kinetics. Studies have shown that metal ion pre-introduction is an effective method to solve these problems and enhance battery performance. Here, the introduction of Al³⁺ , Cr³⁺ , Cu²⁺ and Fe³⁺ is found to effectively reduce the migration energy barrier of Zn²⁺ with the density functional theory calculations, while Al³⁺ exhibits the best induction effects. Subsequently, Al_0.34 V₅ O₁₂ ·2.4H₂ O (AlVOH) nanoribbons are synthesized by hydrothermal introduction of Al³⁺ , demonstratin excellent electrochemical properties (407.8 mAh g^-1 at 0.2 A g^-1 and 176.3 mAh g^-1 after 2000 cycles at 20 A g^-1 ). By further compounding with redox graphene (rGO), AlVOH/rGO exhibits high capacitance and specific capacity (460.4 mAh g^-1 at 0.2 A g^-1 and 180.6 mAh g^-1 after 2000 cycles at 20 A g^-1 ). In addition, it is found that the introduction of metal ions adjusts the structural water content of the material. Especially, the introduction of Al³⁺ can increase the interlayer structural water content and make the electrochemical properties of the material more stable.