Abstract: Vanadium nitride (VN), a promising cathode material for aqueous zinc ion batteries (AZIBs), undergoes irreversible phase transitions accompanied by structural variation and sustained vanadium dissolution, which impair cycling stability and reaction kinetics. To address these challenges, we designed a core-shell heterostructure (VONC-T, T represents temperature) composed of a VN core and a porous carbon shell. This structure was synthesized via in-situ construction, involving optimized ratio of coating a zinc-based zeolitic imidazolate framework (ZIF-8) onto a vanadium-based metal-organic framework (MIL-47(V)), followed by a thermal treatment. This process ensures a high degree of interfacial stability between the core and shell, effectively mitigating the structural variation of VN during irreversible phase transitions and enhancing the overall structural stability. During thermal driving, the volatilization of zinc within the shell layer created a porous channel effect, which facilitating Zn²⁺ diffusion. The enhancement of Zn²⁺ diffusion strengthens the efficient conversion of VN to amorphous VO_x, labeled as VONC-T- a, which provides more active sites and consequently results in a high specific capacity. The optimized heterostructure of VONC-900-a presented high reversible capacity of 387.2 mAh g^-1 at 0.2 A g^-1 and demonstrated excellent rate performance, achieving 274.5 mAh g^-1 at 20 A g^-1, while maintaining a capacity retention rate of 93.3 % after 5000 cycles at 10 A g^-1. Density functional theory calculations confirmed improved reaction kinetics in the core-shell structure. This study not only highlights the potential of amorphous vanadium oxide core-shell heterostructure for AZIBs but also provides new insights into the conversion mechanisms of VN.

Key words: Aqueous zinc ion battery, Core-shell structure, Vanadium nitride, Metal-organic framework, Density functional theory