Heterostructure engineering coupled with in situ activation enables ultra‐high capacity and fast zinc‐ion storage kinetics in vanadium‐based cathodes

Abstract Vanadium‐based materials are recognized as promising cathodes for high‐energy‐density aqueous zinc‐ion batteries (AZIBs). However, their inherent low intrinsic conductivities and sluggish reaction kinetics curtail their capacity release. Here, we enhanced the electron and ion transport properties of vanadium‐based cathodes through heterojunction engineering, coupled with in situ electrochemical activation, significantly enhancing an unprecedented zinc‐ion storage capacity and rapid kinetic performance. A heterostructured V 2 O 3 /g‐C 3 N 4 (V 2 O 3 /CN) precursor was synthesized via a calcination process firstly. When employed as a cathode in AZIBs, this precursor undergoes an in situ phase transformation into Zn 3 (OH) 2 V 2 O 7 ·2H 2 O/C 3 N 4 (ZVOH/CN) during the inaugural charging process, while retaining its heterojunction structure. Both electrochemical assessments and theoretical calculations revealed that ZVOH/CN exhibits superior zinc‐ion adsorption and migration capabilities compared to conventional vanadium‐based cathodes. The formation of the heterojunction amplifies the material’s electronic conductivity and ion diffusion kinetics. As a result, the optimal ZVOH/CN composite electrode showcases a remarkable capacity of 518.5 mAh g −1 at 0.5 A g −1 , superior rate performance of 177.8 mAh g −1 at 20 A g −1 , and impressive cycling stability. This work offers a novel design strategy for vanadium‐based composite materials as high‐performance AZIB cathodes.