Facile Fabrication of Oxygen‐Defective (NH 4 ) 2 V 10 O 25 ·8H 2 O/MXene Cathode with Synergistic Enhancement for High‐Performance Zn 2+ Storage

Vanadium‐based materials have gained considerable attention as attractive cathodes for aqueous zinc‐ion batteries (AZIBs) owing to their high theoretical capacity and economic advantages. Nevertheless, their practical use remains challenging due to the intrinsic limitations, including structural instability, poor conductivity, and sluggish Zn 2+ diffusion kinetics. Herein, we present an oxygen‐defective (NH 4 ) 2 V 10 O 25 ·8H 2 O/MXene (O d ‐NVO/MXene) composite with flower‐like architecture by sonicating MXene with 1 h hydrothermally synthesized NVO for 5 min. Oxygen defects weaken the electrostatic interaction between V–O and Zn 2+ , lower the diffusion barrier, and thus accelerate the reaction kinetics. Meanwhile, MXene acts as a highly conductive scaffold and builds a continuous network that substantially improves the electronic conductivity. As expected, the optimized cathode exhibits extraordinary electrochemical performance with high specific capacity (418 mAh g −1 at 1 A g −1 ), remarkable cycling stability (96.4% capacity retention after 2000 cycles at 5 A g −1 ), and high energy density (330 Wh kg −1 ). Furthermore, the quasi‐solid‐state battery incorporating O d ‐NVO/MXene demonstrates exceptional mechanical flexibility and desired electrochemical behavior. This work proposes a facile and effective strategy to enhance the electrochemical performance of (NH 4 ) 2 V 10 O 25 ·8H 2 O, laying the foundation for advanced vanadium‐based electrodes in AZIBs.