Hydrophobic Hyamine‐Mediated Water‐Lean Electric Double Layer Boosting Reversible Dendrite‐Free Zinc Metal Anodes

Abstract Aqueous zinc‐ion batteries (ZIBs) are promising candidates for grid‐energy storage due to their safety and cost‐effectiveness. However, the detrimental hydrogen evolution reaction (HER) and dendrite growth on Zn‐metal anodes severely limit their applications. Herein, trace hydrophobic hyamine (HQA, 0.78 mmol L⁻¹) is introduced as an electrolyte additive to improve the electrochemical performance of the Zn anode. Experiments and theoretical calculations revealed that cationic HQA can preferentially adsorb onto the anode surface to inhibit the HER and promote the uniform distribution of Zn ions by forming a water‐lean electric double layer (EDL). Moreover, the oriented adsorption of HQA induced exposure of the Zn (002) plane and prevented dendrite growth. Therefore, the symmetric cells using the HQA‐containing electrolyte exhibited stable cycle performance for more than 1600 h. Even at a high‐density current of 5 mA cm⁻², it has a high cumulative capacity of 3250 mAh cm⁻². It exhibited an excellent deep‐discharge performance (80%) with a stable cycle for 175 h. The Zn||NH₄V₄O₁₀ full cell exhibited a high specific capacity and cycle stability at 4.0 A g⁻¹ due to the excellent reversibility of Zn anode. These results provide a new and low‐cost approach for electrolyte design and EDL optimization of high‐performance zinc‐ion batteries.