Spatially Coupling Electronic-Ionic Transport in Organic Mixed Conductors as Cathodes for Efficient Zn-V Batteries

In conventional electrodes, concentration polarization by unbalanced charge transport and solid-state diffusion resistance result in sluggish reaction kinetics, hindering the practical application of zinc-ion batteries. Here, we propose an integrated mixed electronic-ionic conductor by spatially coupling charge transport pathways, which could achieve redistribution and fast transport of charge (Zn²⁺/e^-). Operando electrochemical quartz crystal microbalance and electrochemical impedance spectroscopy revealed the charge transport mechanisms and intrinsic conducting characteristics at timescale. Through confinement by vanadium oxide, dual-conductive pathways were self-assembled at the nanoscale and provided effective charge storage. This provided high charge density and accelerated ionic diffusion in the bulk phase, resulting in more active sites and faster reaction kinetics. Moreover, reversible ionic channels from the self-doping/de-doping process reduced the dissolution of active materials by protons and enabled conversion chemistry, improving cycling stability at low current density. Consequently, the modulated cathode (PEDOT-SO₃-ZnVO) delivered a high-rate performance of 310/148 mAh g^-1 (0.2/10 A g^-1) at 10 mg cm^-2. Importantly, the conventional electrode at 21 mg cm^-2 achieved an ultra-high areal capacity of 6.0 mAh cm^-2 and superior cycling stability (79.1% retention over 100 cycles at 0.2 A g^-1). This work opens the way for the precise modulation of the electrochemical performance of functional nanomaterials.