Decoupling Bulk Kinetics and Surface Stability: A Dual‐Regulation Strategy for High‐Performance Ammonium Vanadate Cathodes in Aqueous Zinc‐Ion Batteries

ABSTRACT Aqueous zinc‐ion batteries (AZIBs) hold promise for sustainable energy storage, but high‐capacity ammonium vanadate (NH 4 V 4 O 10 , NVO) cathodes suffer from sluggish Zn 2+ kinetics and structural degradation via vanadium dissolution. To overcome these persistent bottlenecks, we propose a decoupled dual‐modification strategy integrating the controlled partial substitution of interlayer NH 4 + with hydronium ions (H 3 O + ) and the in‐situ formation of a conformal poly(3,4‐ethylenedioxythiophene) (PEDOT) conductive network. Mechanistic and density functional theory (DFT) studies reveal that acid‐induced proton exchange expands the interlayer spacing, significantly lowering the Zn 2+ diffusion barrier. Conversely, the PEDOT coating acts as a “structural‐electronic” bridge, compensating for the conductivity loss associated with deammoniation while serving as a robust physical barrier that suppresses the formation of the electrochemically inactive Zn 3 (OH) 2 V 2 O 7 ·2H 2 O passivation layer. The resulting NVO@PEDOT cathode delivers an exceptional specific capacity of 360.2 mAh g −1 , superior rate capability (110 mAh g −1 at an ultra‐high current density of 30 A g −1 ), and remarkably robust cycling stability. It retains 94.0% of the capacity after 200 cycles at 0.5 A g −1 and 69.2% after 10 000 cycles at a high rate of 15 A g −1 . This work establishes a versatile design strategy for decoupling kinetic and stability challenges in the cathode, paving the way for practical, high‐rate AZIBs.