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

摘要

Aqueous rechargeable Zn metal batteries (AZMBs) have attracted widespreadattention due to their intrinsic high volumetric capacity and lowcost. However, the unstable Zn/electrolyte interface causes Zn dendritegrowth and side reactions, resulting in poor Coulombic efficiency andunsatisfactory lifespan. Herein, a SiO_2 reinforced-sodium alginate (SA)hybrid film is designed to regulate solid–liquid interaction energy and spatialdistribution of all species in the electric double layer (EDL) near the Znelectrode. The unique interfacial layer gives rise to a uniform distribution ofZn~(2+) in the Helmholtz layer through solvation sheath modulation. Moreover,theoretical calculations show that the SO_4~(2?) anions and free-waterare substantially reduced in the Helmholtz layer, effectively suppressinghydrogen evolution reaction and formation of by-products through strongcharge repulsion and hydrogen bond fixing of free-water. The reconfiguredEDL not only ensures homogenous and fast Zn~(2+) transport kinetics fordendrite-free Zn deposition, but also eliminates interface parasitic sidereactions. The Zn@SiO_2-SA electrode enables excellent cycling stability ofsymmetrical cells and high-loading full AZMBs with a lifespan over 3000 hand an areal capacity of 2.05 mAh cm~(?2), thus laying a solid basis for realizingpractical AZMBs.