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

Abstract 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 H 2 O environment via hydrogen‐bond anchoring to reduce thermodynamically active H 2 O, facilitate desolvation kinetics, and uniform Zn 2+ 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–I 2 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.