Layered (AlO)₂OH·VO₃ composite superstructures for ultralong lifespan aqueous zinc-ion batteries

The unique superstructures electrode materials are of dominant significance for improving the performance of aqueous zinc-ion batteries (AZIBs). In this work, using nano MIL-96 (Al) as the precursor, a series of the layered (AlO)₂OH·VO₃ composite superstructures with different morphologies and V-oxide contents were prepared by combining calcination and hydrothermal synthesis. Among which, the HBC₆₅₀·V₄ superstructure is composed of the amorphous Al₂O₃/C, V-oxide, and the fluffy structure of (AlO)₂OH, thus the superstructure can enhance the stability, increase the active center, and shorten Zn²⁺ diffusion, respectively. It is commendable that, the HBC₆₅₀·V₄ superstructure exhibits a high specific capacity of 180.1 mAh·g^-1 after 300 cycles at 0.5 A·g^-1. Furthermore, the capacity retention can be as high as 99.6 % after 5000 cycles at a high current density of 5.0 A·g^-1, showing superior long cycling stability. Importantly, the in-situ XRD patterns and ex-situ analysis revealed the structural changes and reaction mechanisms of the HBC₆₅₀·V₄ superstructure during Zn²⁺ insertion/extraction. Therefore, the HBC₆₅₀·V₄ superstructure prepared using Al-MOF exhibits the advanced AZIBs performance. The preparation of nano-MOF into multifunctional superstructures through innovative strategies will be development trend in this field, which opens a new way to design AZIBs cathode materials.