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Rechargeable aqueous zinc-ion batteries (AZIBs) have garnered widespread attention as a new large-scale energy storage candidate owing to their low cost and high theoretical capacity. Because of the unique divalent state of Zn2+ and the existence of a strong electrostatic repulsion phenomenon, researchers are currently focusing on how to prepare high-performance cathode materials. In this study, we synthesized aluminum vanadate (AlV3O9) as a cathode material for AZIBs using a solvothermal method. Al3+ acted as a pillar in the resultant structure and stabilized it. Furthermore, this large interlayer spacing enhanced the ion diffusion coefficient and accelerated the ion transport process. Because of these advantages, the AlV3O9 (AVO) cathode exhibited excellent electrochemical performance, including a high capacity of 421.0 mA h g−1 at 0.1 A g−1 and a stable rate capability of 348.2 mA h g−1 at 1 A g−1. Moreover, it exhibited a specific capacity of 202 mA h g−1 even at a high current density of 3 A g−1 (the capacity retention rate reached 84.38% after 1600 cycles). The prepared ZIBs presented a high power density of 366.6 W kg−1 at an energy density of 286 W h kg−1. These extraordinary results indicate the great application potential of AVO as a cathode material for AZIBs. [ABSTRACT FROM AUTHOR]

VO2 generally has a higher theoretical capacity and layered structure suitable for the intercalation/extraction of zinc ions. However, Zn2+ ions with high charge density interact with the crystal lattice and limit further improvement in electrochemical performance. Defect engineering is a potential modification method with very promising application prospects, but the established procedures for preparing defects are complicated. In this study, VO2–x(B) with oxygen deficiency is prepared by a simple solution reaction with NaBH4. The presence of oxygen deficiencies is confirmed by positron annihilation lifetime spectroscopy, UV/Vis absorbance spectroscopy and others. Owing to the presence of oxygen defects, the aqueous Zn/VO2–x(B) battery exhibits improved specific capacity, excellent reversibility, and structural stability. Ex situ characterization techniques are employed to demonstrate the reversible insertion‐extraction mechanism of Zn2+ ions from and into the host material. In addition, the Zn/VO2–x(B) batteries still exhibit considerable electrochemical performance, even with high‐loading electrodes (about 4 mg cm−2). [ABSTRACT FROM AUTHOR]

• Hydrated zinc vanadate was formed from V 2 O 5 via an initial activated phase transformation process induced by H 2 O. • Hydrated zinc vanadate combines two modification strategies of special morphology and crystal structure adjustment. • Hydrated zinc vanadate exhibited considerable exhibited enhanced cycle performance and improved reaction kinetics. • Activated phase transformation was demonstrated to be an effective method to improve the electrochemical performance. Aqueous zinc-ion batteries have great potential applications in the field of energy storage; however, their development is limited by the low availability of high-performance cathode materials. In this study, the phase transformation of Yolk-shell V 2 O 5 (YS-V 2 O 5) to hydrated zinc vanadate (Zn 0.34 V 2 O 5 •0.37H 2 O; HZVO) was driven by water molecules via electrochemical activation. The resulting HZVO was used as the host material for the insertion/extraction of zinc ions. The HZVO material exhibited a specific capacity of 85.2% (113.3 mA h g−1) after 1000 cycles at a current density of 8.0 A g−1. Moreover, the diffusion coefficient of zinc ions was larger than that of conventional cathode materials, ranging from 10−9 to 10−8 cm2 s−1. We believe that our approach can contribute to the development of advanced cathode materials for application in zinc-ion batteries. [ABSTRACT FROM AUTHOR]