Nickel-mediated V4O7 as high-performance cathode material for aqueous Zn-ion batteries

Vanadium-based materials are currently favored by researchers due to their multi-structure, which can enhance the steric resistance and electrostatic repulsion during the (de)intercalation process of zinc ions. However, their low conductivity remains an inherent hindrance to their practical application. Therefore, finding a way to adjust the electronic structure of vanadium-based compounds is considered an effective strategy. Presently, we have designed a porous Ni-mediated V₄O₇, wherein the presence of oxygen defects and heterostructures in V₄O₇/NiO (O_d-NVO-4) substantially improves the diffusion kinetics of ions/electrons and boosts the electrochemical performance. As anticipated, the Zn//V₄O₇/NiO battery exhibits a high specific capacity (348.6 mAh g⁻¹ at 0.1 A g⁻¹), favorable rate capability (323.8 mAh g⁻¹ at 4 A g⁻¹), and remarkable cycle stability (206.3 mAh g⁻¹ at 2 A g⁻¹ after 2000 cycles). Additionally, the underlying mechanism of electrochemical zinc storage is comprehensively described through electrochemical kinetic analysis and theoretical calculations. These results unambiguously reveal the intrinsic link between the surface/interface structure and electrochemical performance of the cathode, offering a valuable reference for designing high-performance electrode materials.