A two-dimensional conductive polymer/VO 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 Zn diffusion kinetics in the VO framework and poor intrinsic conductivity result in inferior rate capability and unsatisfactory cycling performance of the VO 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 VO not only remarkably enlarges the interlayer distance for facile Zn 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 Zn insertion. As a result, the PEDOT-intercalated VO (PEDOT/VO) exhibits a good high-rate performance (154 mA h g at an ultrahigh current density of 50 A g) and a long-term cycling life (maintains 170 mA h g even after 2500 cycles at 30 A g). This universal strategy provides a design principle for constructing efficient Zn and electron transport pathways within cathode materials, holding great potential for the development of high-performance and durable ZIB cathodes.