Eliminating Dendrites and Side Reactions via a Multifunctional ZnSe Protective Layer toward Advanced Aqueous Zn Metal Batteries

The development of aqueous Zn metal batteries (AZMBs) is impeded by severe corrosion, H2 evolution, and dendrite formation issues. In addition, the inability of AZMBs to achieve a large capacity also hinders their commercialization. Here, a multifunctional ZnSe protective layer is reported to synchronously solve the above issues. The ZnSe layer can efficiently provide anticorrosion while also suppressing hydrogen evolution. Systematic analyses of the mechanism suggest that the low Zn affinity of ZnSe and the unbalanced charge distribution at the interface can promote a uniform distribution of Zn2+ and accelerate Zn2+ migration, thus realizing dendrite‐free behavior. Therefore, the Zn@ZnSe symmetric cell exhibits notable rate performance and cycling stability (1500 h). Moreover, this symmetric cell can still stabilize with a low polarization (50 mV), even at 10 mA cm−2 with 5 mAh cm−2. The full cell paired with MnO2 achieves a long lifespan (1800 cycles) with a Coulombic efficiency near 100%. Therefore, this strategy for eliminating dendrites and side reactions at a high rate with a large capacity provides a promising solution for the development of AZMBs. A multifunctional ZnSe protective layer is fabricated to eliminate Zn dendrites and side reactions synchronously. The Zn@ZnSe symmetric cell exhibits prominent stability even at 10 mA cm‐2 with 5 mAh cm‐2. The full cell achieves a long lifespan with a Coulombic efficiency nearing 100%. The mechanism is deeply investigated via in situ experiments and systematic density functional theory calculations.