Ion-directed polymer/inorganic interphase with enriched charge for stable and high-rate Zn anodes

Abstract

The rate performance of Zn anodes is a crucial factor for practical zinc-ion batteries; however, concentration gradients and the aggregation of zinc ions at the interface hinder their reversibility. Herein, we use in situ chemical corrosion to construct an artificial solid electrolyte interphase on Zn foil that is composed of an external conducting polymer (PEDOT-SO₃H) and an internal layered zinc sulfate hydroxide hydrate (LZHS). The polymer layer provides a capacitive effect and ionic selectivity for Zn²⁺ enrichment while repelling SO₄²⁻ due to its negative charge. Spontaneously, the –SO₃⁻ group accelerates the desolvation of Zn(H₂O)₆²⁺, thereby achieving fast plating kinetics. Moreover, by chemical corrosion and polymer restriction, the preferred orientation of the LZHS along (001) was tailored, guiding the uniform deposition of zinc ions along (002) by lattice–lattice matching. Consequently, the modulated anode (PZn) delivered an excellent rate performance at 20 mA cm⁻² over 1500 h (a cumulative plating capacity of 15 Ah cm⁻²). The full cell with a K_xMnO₂ cathode delivered an impressive capacity retention of 80.1% at 1 A g⁻¹ over 1000 cycles. The Ah-level pouch cell further demonstrated the practical applicability of the aqueous zinc-ion batteries. This work offers a feasible strategy for tailoring the functional interface towards practical Zn anodes using a conducting polymer.