Interfacial polymerization of PEDOT sheath on V2O5 nanowires for stable aqueous zinc ion storage

Abstract

V₂O₅ is one of the promising cathodes for aqueous zinc ion batteries. However, its performance is largely hindered by its low conductivity and poor cycling stability due to the electrode dissolution. In this work, an interfacial polymerization strategy is developed to prepare the V₂O₅@poly(3,4-ethylenedioxythiophene) (PEDOT) core-sheath nanowire electrode. The interfacial redox reactions between the vapor 3,4-ethylenedioxythiophene molecules and V₂O₅ nanowires initiate the polymerization reaction to yield uniform PEDOT sheaths with varying thickness controlled by the reaction duration. The PEDOT sheaths are found to improve the electrode conductivity, suppress the V₂O₅ nanowire dissolution, and improve the specific capacity. Theoretical simulation further shows that the PEDOT sheath weakens the interactions between Zn²⁺ and the V₂O₅ host, thus benefiting the extraction of Zn²⁺ from the host electrode and boosting the cycling stability. Consequently, V₂O₅@PEDOT-50m delivers a specific capacity of 293 mA h g⁻¹ at 0.1 A g⁻¹ and 225 mA h g⁻¹ at 1 A g⁻¹, which are superior to 205 mA h g⁻¹ and 142 mA h g⁻¹ of the pristine V₂O₅ nanowire electrode, respectively. Moreover, V₂O₅@PEDOT-50m maintains 97.8% and 99% capacity retention after 100 and 2000 cycles, respectively. The significantly enhanced performances with respect to the corresponding V₂O₅ nanowire counterpart demonstrate that the PEDOT sheaths developed by the interfacial polymerization could become an effective method to stabilize the vanadate-based cathodes for zinc ion storage.