Designing Dendrite‐Free Zinc Anodes for Advanced Aqueous Zinc Batteries

• Published in: Advanced functional materials 2020-07, Vol.30 (30), p.n/a
• Main Authors: Hao, Junnan, Li, Xiaolong, Zhang, Shilin, Yang, Fuhua, Zeng, Xiaohui, Zhang, Shuai, Bo, Guyue, Wang, Chunsheng, Guo, Zaiping
• Format: Article
• Language: English
• Subjects: Anodes; aqueous Zn battery; artificial SEI layer; by‐products; Dendritic structure; Electrolytes; Ion currents; Manganese dioxide; Materials science; Plating; Polyvinyl acetal resins; Polyvinyl butyral; side reactions; Stripping; Zinc; Zn dendrites
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202001263

Zn metal has been regarded as the most promising anode for aqueous batteries due to its high capacity, low cost, and environmental benignity. Zn anode still suffers, however, from low Coulombic efficiency due to the side reactions and dendrite growth in slightly acidic electrolytes. Here, the Zn plating/stripping mechanism is thoroughly investigated in 1 m ZnSO4 electrolyte, demonstrating that the poor performance of Zn metal in mild electrolyte should be ascribed to the formation of a porous by‐product (Zn4SO4(OH)6·xH2O) layer and serious dendrite growth. To suppress the side reactions and dendrite growth, a highly viscoelastic polyvinyl butyral film, functioning as an artificial solid/electrolyte interphase (SEI), is homogeneously deposited on the Zn surface via a simple spin‐coating strategy. This dense artificial SEI film not only effectively blocks water from the Zn surface but also guides the uniform stripping/plating of Zn ions underneath the film due to its good adhesion, hydrophilicity, ionic conductivity, and mechanical strength. Consequently, this side‐reaction‐free and dendrite‐free Zn electrode exhibits high cycling stability and enhanced Coulombic efficiency, which also contributes to enhancement of the full‐cell performance when it is coupled with MnO2 and LiFePO4 cathodes. Zn metal electrode suffers from poor Coulombic efficiency and limited reversibility in mild electrolytes due to the Zn dendrite growth, Zn electrode corrosion, and hydrogen evolution. An artificial polyvinyl butyral interphase is built on the Zn metal surface to suppress the side reactions and Zn dendrite growth, which effectively enhances the Zn electrode performance.