Reconstruction of Electric Double Layer for Long‐Life Aqueous Zinc Metal Batteries

Abstract Aqueous rechargeable Zn metal batteries (AZMBs) have attracted widespread attention due to their intrinsic high volumetric capacity and low cost. However, the unstable Zn/electrolyte interface causes Zn dendrite growth and side reactions, resulting in poor Coulombic efficiency and unsatisfactory lifespan. Herein, a SiO2 reinforced‐sodium alginate (SA) hybrid film is designed to regulate solid–liquid interaction energy and spatial distribution of all species in the electric double layer (EDL) near the Zn electrode. The unique interfacial layer gives rise to a uniform distribution of Zn2+ in the Helmholtz layer through solvation sheath modulation. Moreover, theoretical calculations show that the SO42− anions and free‐water are substantially reduced in the Helmholtz layer, effectively suppressing hydrogen evolution reaction and formation of by‐products through strong charge repulsion and hydrogen bond fixing of free‐water. The reconfigured EDL not only ensures homogenous and fast Zn2+ transport kinetics for dendrite‐free Zn deposition, but also eliminates interface parasitic side reactions. The Zn@SiO2‐SA electrode enables excellent cycling stability of symmetrical cells and high‐loading full AZMBs with a lifespan over 3000 h and an areal capacity of 2.05 mAh cm−2, thus laying a solid basis for realizing practical AZMBs.