An in-depth insight of a highly reversible and dendrite-free Zn metal anode in an hybrid electrolyte

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2021-01, Vol.9 (7), p.4253-4261
• Main Authors: Zhang, Yuanjun, Zhu, Ming, Wu, Kuan, Yu, Fangfang, Wang, Guanyao, Xu, Gang, Wu, Minghong, Liu, Hua-Kun, Dou, Shi-Xue, Wu, Chao
• Format: Article
• Language: English
• Subjects: Anodes; Aqueous electrolytes; Batteries; Dendritic structure; Electrochemical analysis; Electrochemistry; Electrolytes; Glycerol; Glycerol-Water; Metals; Plating; Redox potential; Sheaths; Side reactions; Solvation; Stripping; Toxicity; Zinc
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d0ta11668h

Zn metal is considered as one of the most promising anodes for aqueous high-energy batteries owing to its high theoretical capacity, low redox potential, abundant resource, and low toxicity. However, Zn metal anodes (ZMAs) still suffer from a few challenging problems such as low irreversibility and dendrite growth during plating/stripping. In this study, we identify and quantify the composition of inactive Zn responsible for capacity loss, which shows that it contains 57 mol% of unreacted Zn 0 and 43 mol% Zn-containing byproducts. Based on this quantitative result, we developed an environmentally friendly water/glycerol hybrid electrolyte, which enable the dendrite-free plating/stripping of Zn with a high coulombic efficiency of 97.6% over 500 cycles. A symmetric Zn|Zn cell can be repeatedly plated/stripped for more than 1500 h at 1 mA cm −2 . Glycerol can suppress the side reactions caused by water in the hybrid electrolyte because of the strong binding interactions between glycerol and the Zn metal. The molecular-scale modeling simulations and electrochemical analysis reveal that the dense and uniform Zn electro-deposition is related to the Zn 2+ -solvation-sheath structure. The fundamental understanding of ZMAs in aqueous and hybrid electrolytes opens a viable route for the highly efficient utilization of Zn with high efficiency and safety. The composition of inactive Zn responsible for the capacity loss is identified and quantified. Based on this result, an environmentally friendly glycerol/water hybrid electrolyte is developed to promote the uniform deposition of the Zn metal.