A hydrated deep eutectic electrolyte with finely-tuned solvation chemistry for high-performance zinc-ion batteries

• Published in: Energy & environmental science 2023-06, Vol.16 (6), p.254-2549
• Main Authors: Chen, Ruwei, Zhang, Chengyi, Li, Jianwei, Du, Zijuan, Guo, Fei, Zhang, Wei, Dai, Yuhang, Zong, Wei, Gao, Xuan, Zhu, Jiexin, Zhao, Yan, Wang, Xiaohui, He, Guanjie
• Format: Article
• Language: English
• Subjects: Aqueous electrolytes; Electrochemical analysis; Electrochemistry; Electrolytic cells; Mass transfer; Moisture content; Rechargeable batteries; Side reactions; Solvation; Water content; Zinc
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d3ee00462g

Despite their cost-effectiveness and intrinsic safety, aqueous zinc-ion batteries have faced challenges with poor reversibility originating from various active water-induced side reactions. After systematically scrutinizing the effects of water on the evolution of solvation structures, electrolyte properties, and electrochemical performances through experimental and theoretical approaches, a hydrated deep eutectic electrolyte with a water-deficient solvation structure ([Zn(H 2 O) 2 (eg) 2 (otf) 2 ]) and reduced free water content in the bulk solution is proposed in this work. This electrolyte can dramatically suppress water-induced side reactions and provide high Zn 2+ mass transfer kinetics, resulting in highly reversible Zn anodes (∼99.6% Coulombic efficiency over 1000 cycles and stable cycling over 4500 h) and high capacity Zn//NVO full cells (436 mA h g −1 ). This work will aid the understanding of electrolyte solvation structure-electrolyte property-electrochemical performance relationships of aqueous electrolytes in aqueous zinc-ion batteries. A hydrated deep eutectic electrolyte with a water-deficient solvation structure and reduced free water in bulk solution is proposed, resulting in highly reversible and stable Zn anodes.