A two-dimensional conductive polymer/V₂O₅ composite with rapid zinc-ion storage kinetics for high-power aqueous zinc-ion batteries

Abstract

Vanadium oxides represent a promising cathode material for aqueous zinc ion batteries (ZIBs) owing to their abundant valences and versatile cation-storage capacities. However, the sluggish Zn²⁺ diffusion kinetics in the V₂O₅ framework and poor intrinsic conductivity result in inferior rate capability and unsatisfactory cycling performance of the V₂O₅ cathode, and thus limits its commercial-scale deployment. Herein, a unique conducting polymer intercalation strategy is developed to optimize the ion/electron transport simultaneously based on the rational design of the composite structure and morphology. The poly(3,4-ethylenedioxythiophene) (PEDOT) intercalated V₂O₅ not only remarkably enlarges the interlayer distance for facile Zn²⁺ diffusion, but also diminishes the electron transport resistance by the π-conjugated structure of PEDOT. Additionally, the two-dimensional (2D) morphology enables shorter ion diffusion paths as well as a larger number of exposed sites for Zn²⁺ insertion. As a result, the PEDOT-intercalated V₂O₅ (PEDOT/V₂O₅) exhibits a good high-rate performance (154 mA h g^-1 at an ultrahigh current density of 50 A g^-1) and a long-term cycling life (maintains 170 mA h g^-1 even after 2500 cycles at 30 A g^-1). This universal strategy provides a design principle for constructing efficient Zn²⁺ and electron transport pathways within cathode materials, holding great potential for the development of high-performance and durable ZIB cathodes.