Engineering d-p orbital hybridization through regulation of interband energy separation for durable aqueous Zn//VO2(B) batteries

VO2(B) is considered as the leading candidate cathode materials for AZIBs, however, the primary challenge of slow kinetics and limited actual capacity remains unresolved to date well in modification strategy. Significantly, the insights into the mechanism of ion doping, one of the most effective measures, have not been explored well. Herein, we proposed and unveil that reactivity of vanadium atoms and the Zn2+ ion adsorption energy in VO2(B) can be related to the theoretical model Δd-p based on the band-center of heteroatom and surrounding coordination oxygen via the density functional theory (DFT). Accordingly, the heteroatom (Cr, Mo and W)-doped VO2(B) cathode was proposed for AZIBs and it can well verify the above theoretical calculation results. Typically, the Mo-doped VO2(B) delivers the best comprehensive electrochemical performance, and it owns excellent initial specific capacity (264.6 mA h g−1) and retention rate (81.4 %) can be obtained at the 3.0 A g−1 after 3000 cycles. And, it also shows a much faster Zn2+ ion diffusion coefficient (2.1×10−8 vs 2.6×10−9 cm2 S−1) than that of pure VO2(B). Meanwhile, the promising energy density of 207.3 Wh kg−1 at 0.1 A g−1 and power density of 3094.5 W kg−1 at 5.0 A g−1 also was achieved. This finding can help understand the modification mechanism of heteroatom-doping materials and fundamentally guide the electrode design to improve performance.