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, Al0.34 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.