Ion Diffusion-Directed Assembly of an Artificial Electronic–Ionic Conductor Layer with Zn-Ion Selective Channels for Highly Reversible Zinc Anodes

Although aqueous zinc-ion batteries have attracted much attention due to their high safety, low cost, and relatively high energy density, their practical applications are severely limited by the uncontrollable dendrite growth and side reactions at the zinc anode. Herein, we design an electronic-ionic conductor artificial layer with Zn-ion selective channels on the Zn surface to regulate the Zn plating/stripping behavior through a one-step ion diffusion-directed assembly strategy using the commercially available conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). Significantly, the functional PEDOT:PSS-Zn²⁺ (PPZ) layer with abundant selective Zn-ion channels works as both an electron regulator and an ion regulator that could not only simultaneously uniformize the electrical and Zn²⁺ concentration field on the Zn surface and accelerate the Zn²⁺ transport kinetics but also block the access of SO₄^2- and H₂O. With such a synergy effect, the PEDOT:PSS-Zn²⁺-modified Zn anode (2PPZ@Zn) achieves a long lifespan of 2400 h of the symmetrical cell at a current density of 3 mA cm^-2 (1 mA h cm^-2). Additionally, a long-term lifespan of 500 h is harvested even at a high current of 5 mA cm^-2 with a high capacity of 3 mA h cm^-2. Furthermore, combined with a manganese dioxide cathode, a full cell similarly provides a cycling stability of over 1500 cycles with 75% capacity retention at a high rate of 10 C (1 C = 308 mA h g^-1).