Dienoic‐Acid Coupling Effect Induced Hierarchical Interface for High‐Performance Zinc Metal Batteries

Rational pre-design of self-decomposed electrolyte additives to construct solid electrolyte interphase (SEI) for suppressing hydrogen evolution reaction (HER) and dendrite growth of zinc (Zn) anode confronts enormous challenges, especially for the in-depth understanding of structure-function relationship and the lack of reasonable design criteria. In this work, the dienoic-acid coupling effect is innovatively proposed to in-situ construct a hierarchical SEI layer (HSL) through the structural screening of a series of organic-acid molecules. Strong electron-withdrawing ability of dual carboxyl and metastable double bond can strengthen the self-decomposition tendency of trace electrolyte additive to form HSL via chemical and electrochemical reaction. HSL can effectively regulate interfacial H₂O environment via hydrogen-bond anchoring to reduce thermodynamically active H₂O, facilitate desolvation kinetics, and uniform Zn²⁺ diffusion, thus significantly suppressing HER and dendrite growth. As a result, Zn anode with HSL can achieve high average coulombic efficiency of 99.8% over 2400 cycles, long-term cycling stability of 3800 h, and good reversibility under 50 mA cm^-2. Zn-I₂ full battery with HSL displays a long cycling life of 15 000 cycles and successfully powers the portable and wearable instruments. This work opens a novel route to design an advanced interface with fast kinetics by trace electrolyte additive for high-performance Zn metal batteries.