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

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.