Electrode Interface Engineering of Hydrophilic and Zincophilic Bifunctionality for High‐Efficiency and Low‐Polarization Zn Anodes

Aqueous rechargeable Zn batteries offer a promising technological route as a safe and low‐cost energy storage system for grid energy storage. However, major challenges of Zn dendrites and parasitic side reactions upon cycling in aqueous environments remain unsolved. Here, a design of a bifunctional electrode interface consisting of heterostructured zinc hydroxide chloride (ZHC) and Cu, as well as their synergy in promoting high‐efficiency and low‐polarization Zn deposition is reported. Hydrophilic/zincophobic ZHC promotes the desolvation of hydrated Zn2+ prior to Zn nucleation, meanwhile adjacent Cu acts as a zincophilic site for subsequent nucleation and deposition. Consequently, the reduction polarization of Zn2+ at the bifunctional layer (ZHC‐Cu) features ten times lower nucleation overpotential of 3 mV than bare Zn. Meanwhile, the water‐induced hydrogen evolution side reactions on Zn are significantly hindered by the bifunctionality of the electrode interface. Accordingly, the ZHC‐Cu@Zn symmetric cells exhibit a superior cycling stability for over 3500 cycles at 10 mA cm−2/3 mAh cm−2. The ZHC‐Cu@Zn full‐cell with MnO2 cathode can stably operate for low C‐rate cycling with a high average Coulombic efficiency of 99.5% over 600 cycles. This work provides an effective approach to rational design of heterostructured bifunctional electrode interfaces to obtain high‐efficiency and low‐polarization Zn anodes. A bifunctional interfacial modification layer integrating zincophilicity and hydrophilicity is prepared to reduce minimally the reduction polarization of Zn2+ on zinc anodes. The hydrated Zn2+ accomplishes rapid desolvation on the hydrophilic/zincophobic zinc hydroxide chloride and diffuses rapidly to the zincophilic Cu for deposition. The modification layer also inhibits water‐induced side reactions.