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 SiO 2 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 Zn 2+ in the Helmholtz layer through solvation sheath modulation. Moreover, theoretical calculations show that the SO 4 2− 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 Zn 2+ transport kinetics for dendrite-free Zn deposition, but also eliminates interface parasitic side reactions. The Zn@SiO 2 -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.

Metallic Particles‐Induced Surface Reconstruction Enabling Highly Durable Zinc Metal Anode

“…The activation energy is further calculated by Arrhenius equation to evaluate the de‐solvation energy barrier of Zn ions on the surface of Zn anode. [ 38,39 ] As shown in Figure 5d, the InSnRZn electrode represents a lower activation energy of 34.06 kJ mol −1 than bare Zn (47.37 kJ mol −1 ). The lower activation energy implies a much faster rate of Zn ions de‐solvation and less energy consumption of Zn deposition endowed by the indium–tin alloy layer.…”

Refining the Grain Size of Zinc Electrodeposit by Pb2+ Ion Grinding for Compact and Stable Zinc Anode

“…As a result, the Pb 2+ ions are enriched in IHP and tightly adsorb on the electrode surface, which will be more prominent as the current increased. (Figure 3f, and Figure S12, Supporting Information) [17] . Notably, the strong adsorption of Pb 2+ ions on both Zn crystals and electrode surfaces may block the way for the subsequent absorption and electroreduction of Zn 2+ ions, resulting in the grain‐refined Zn units with compactly stacked build‐up (Figure 3d).…”

“…(Figure 3f, and Figure S12, Supporting Information). [17] Notably, the strong adsorption of Pb 2 + ions on both Zn crystals and electrode surfaces may block the way for the subsequent absorption and electroreduction of Zn 2 + ions, resulting in the grain-refined Zn units with compactly stacked build-up (Figure 3d). Importantly, such strong adsorption could also suppress the electrochemical corrosion of Zn anode in aqueous electrolyte, since the corrosion current in ZS + Pb electrolytes was much smaller than that of in ZS electrolytes (Figure S13, Supporting Information).…”

Cation and Anion Modulation Strategies toward Ideal Zinc Artificial Interface

“…To further investigate the existence and influence of anions in EDL, Yang et al [9] proposed and demonstrated that the IHP consists of water dipoles and SO 4 2À anions, and the hydrated Zn 2 + cations can only approach OHP, as displayed in Figure 7a. In addition, some SO 4 2À anions are accompanied with hydrated Zn 2 + cations to maintain charge neutrality.…”