Enhancing proton kinetics in Bi₂O₂Se nanosheets via polymer coating for high-performance aqueous zinc metal batteries

Rechargeable aqueous zinc-ion batteries (AZIBs) offer high ionic conductivity and environmental benefits, making them a promising alternative to lithium-ion batteries (LIBs) for large-scale energy storage. However, the large solvation radius and strong electrostatic interactions of Zn²⁺ can cause structural degradation in most cathode materials during insertion/extraction, limiting the practical application of AZIBs. In this study, a poly(3,4-ethylenedioxythiophene) (PEDOT)-coated bismuth oxyselenide composite (PEDOT@Bi₂O₂Se) was designed to enhance proton kinetics at the electrode surface, thereby increasing the proportion of surface pseudocapacitance. Density functional theory (DFT) calculations indicate that the PEDOT layer provides additional proton adsorption sites, introducing extra electrochemical active sites. Consequently, the PEDOT@Bi₂O₂Se cathode exhibits superior electrochemical performance, delivering a high specific capacity of 503.8 mAh·g⁻¹ at 0.1 A·g⁻¹ and retaining 51.9% capacity after 5000 cycles at 2.0 A·g⁻¹. This work presents a promising and innovative modification strategy for designing high-performance electrodes in next-generation AZIBs.