High-Valence Metal-Ion-Preintercalated Vanadium Oxide as High-Capacity Aqueous Zinc-Ion Battery Cathode Material

The advantages of aqueous zinc-ion batteries (AZIBs) as high-safety and low-cost energy devices show increasingly large potential in grid-scale storage/supply applications. Nevertheless, finding suitable cathode materials is quite challenging for the further development of aqueous ZIBs. In this work, we design a layered porous structure of the chemically pre-intercalated high-valence metal ions into the interlayers of V₂O₅(HM-VOH) with a large interlayer spacing of 11.4 Å by using a scalable hydrothermal method in order to improve the electrode performance of AZIBs. As a result, HM-VOH delivers a higher capacity of c.a. 400 mA h g⁻¹at a current density of 0.1 A g⁻¹and exhibits an excellent capacity retention of &gt; 80% after 300 cycles at a higher current density of 5 A g⁻¹. In addition, we investigated the Zn²⁺ storage mechanism in this HM-VOH cathode material as well as its associated electrochemical kinetics by using <i>Operando</i> synchrotron X-ray diffraction, and operando synchrotron X-ray absorption near-edge spectroscopy. Furthermore, the as-synthesized cathode material can maintain an energy density of &gt; 280 W h kg⁻¹at a high power density of &gt; 70 W kg^−1,which is much higher than the pristine vanadium oxide material. Hence, we found that pre-intercalation of high-valence transition metal ion in the host material allowed rapid diffusion of Zn²⁺, improved electrical conductivity, and excellent structural reversibility, which can be applied to other advanced battery systems.