Polyacrylic Acid Binder Enabling High Areal Capacity V2O5·nH2O Cathode for Aqueous Zinc‐Ion Batteries

Abstract Polyvinylidene difluoride (PVDF) is traditionally used as a cathode binder in aqueous zinc‐ion batteries. However, its poor mechanical properties lead to cycling degradation of the electrodes. Herein, It is reported that polyacrylic acid (PAA) with hydrophilic carboxyl groups can serve as a high‐performance binder for aqueous zinc‐ion batteries. The structure and electrochemical properties of the V 2 O 5 ·nH 2 O electrode is significantly improved by using the PAA binder, showing desirable mechanical properties, enhanced electrolyte wettability, and greatly improved electrochemical reaction kinetics compared to the traditional PVDF binder. The V 2 O 5 ·nH 2 O‐PAA electrode demonstrates a high‐capacity retention of 84.1% after 2000 cycles at the 2 A g −1 current density. Moreover, the thick electrode with a high active material loading of 21.4 mg cm −2 retains a large areal capacity of 7.44 mAh cm −2 with stable cycling, highlighting the great potential of PAA binder in practical aqueous zinc ion batteries.