Suppressing the dissolution of vanadium by organic-inorganic hybrid for aqueous zinc-ion batteries

Vanadium-based materials have been considered as the high promising cathodes for aqueous zinc ion batteries (ZIBs). Nevertheless, the dissolution of vanadium, the structural instability and the poor cycling stability largely hindered their applications. Metal organic frameworks (MOFs) and their derivatives attracted wide attention for their large specific surface area and structural tunability. Herein, MOFs derived·VO2·Zn2V2O7 (MVHA) as organic-inorganic hybrids were constructed by the in-situ substitution method. The mixed valences of V4+ and V5+ between VO2(B) and Zn2V2O7 were helpful to improve the electronic conductivity of MVHA cathode, and MOF-5-V acted as a physical barrier to inhibit the cathodic dissolution attributing to the particular organic frame structure. The obtained hybrid electrodes could deliver a high specific capacity (312.7 mA h g−1 at 1 A g−1), and excellent long-term cycle stability (141.2 mA h g−1 after 1000 cycles at 10 A g−1). Assistant density functional theory (DFT) calculations indicated that it has an ultra-low diffusion barrier of 0.32 eV for optimal Zn2+ diffusion path in MOF-5-V. The intriguing idea of in-situ compositing vanadium oxide and MOFs derived material opens up a new research direction for high-energy secondary batteries.