Citric Acid Induced Dual‐Function Electric Double Layer for High Capacity and Stable Zinc Metal Batteries

The widespread adoption of aqueous zinc metal batteries (AZBs) faces substantial challenges due to the inadequate reversibility, which is primarily manifested in uncontrolled dendrite formation and significant interfacial corrosion. In this study, a unique zincophilic and hydrophobic electric double layer (EDL) has been self‐constructed on the Zn surface via the adsorption and self‐coupling of citric acid (CA) additive. Experimental and calculated results reveal that the trace CA is capable of altering the electrolyte solvation structure and preferentially adsorbing onto the anode surface to form such a unique interface, which can not only facilitate the zinc ions uniform deposition, but also inhibit the interfacial corrosion. Consequently, the assembled AZBs achieve exceptional Coulombic efficiencies (CEs) of 99.9% and 99.8% in the Zn//Cu and Zn//Ti asymmetric batteries, respectively. More excitingly, the Zn//Zn symmetrical batteries demonstrate an excellent lifespan of ∼3000 h at 10 mA cm −2 and 20 mAh cm −2 . Notably, the battery maintains well stability beyond 700 h under harsh conditions of 40 mA cm −2 and 40 mAh cm −2 . Moreover, the assembled Zn//NOVH full battery retains a capacity of 62.68% after 1000 stable cycling at 5 A g −1 . These results offer solid theoretical and technical support for developing a simple and cost‐effective protection strategy of AZB anodes.