New insights into the interfacial characteristics of Poly(Acrylic Acid) binder and hydrated V2O5 cathode material for zinc-ion secondary batteries

Hydrated vanadium pentoxide and poly(acrylic acid) (PAA) are employed as a cathode active material and a binder, respectively, for aqueous zinc-ion secondary batteries (AZIBs). This study investigates the physicochemical interfacial characteristics of the PAA binder, with a particular focus on the intermolecular interactions between the binder and the hydrated V2O5 cathode materials. The PAA binder enables rapid Zn2+ diffusion by providing ion diffusion pathways, thereby enhancing the kinetics of the V2O5 cathode. The PAA binder improves hardness and ion conductivity while reducing the modulus, which results in AZIBs with stable cycle performance under our experimental conditions. The significantly enhanced electrochemical performance is attributed to the strong hydrogen bond and chelation interactions between the PAA and the surface of the hydrated V2O5 cathode materials. Thus, a Zn–V2O5 battery employing a PAA binder outperformed existing AZIBs, showing an impressive capacity of 504.5 mAh g−1 at 0.1 A g−1 and a robust cycling retention of 99.9 % over 1000 cycles, demonstrating the potential of aqueous binders in vanadium-based cathode materials.