Layer-by-Layer Assembled, Mixed Conducting Artificial Layers for Stable Zinc Metal Anodes in Aqueous Batteries

Aqueous zinc-ion batteries are promising energy storage systems owing to the abundance of zinc resources and the safety of aqueous electrolytes. However, direct Zn-electrolyte contact induces dendritic growth and side reactions, compromising cycle life. Herein, a mixed ionic-electronic conducting interphase is fabricated via a layer-by-layer (LBL) assembly of poly(diallyldimethylammonium chloride) (PDDA) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). This interphase i) directs Zn²⁺ flux, ii) maintains electronic conductivity for uniform field distribution, and iii) mitigates water-induced side reactions. Electrochemical and spectroscopic analyses confirm reduced Zn²⁺ desolvation energy and suppressed hydrogen evolution and corrosion. Consequently, Zn/Zn symmetric cells exhibit stable cycling over 1800 h at 1 mA cm^-2, while five bilayers of (PDDA/PEDOT:PSS)-coated Zn/MnO² full cells retain 3.92 mAh cm^-2 after 350 cycles at 0.25 A g^-1. This ecofriendly and cost-effective LBL strategy significantly enhances the energy density and cycle life of aqueous zinc-metal batteries, facilitating their industrial application.