Examining Concentration‐Reliant Zn Deposition/Stripping Behavior in Organic Alcohol/Sulfones‐Modified Aqueous Electrolytes
Weiman Zhuang, Qianwen Chen, Zhen Hou, Zongzhao Sun, Tianxu Zhang, Jianyong Wan, Limin Huang
Abstract
The practical application of Zn metal anodes in electronic devices is hindered by dendrite growth and parasitic reactions. Electrolyte optimization, particularly the introduction of organic co-solvents, is widely used to circumvent these challenges. Various organic solvents in a wide range of concentrations have been reported; however, their influences and corresponding working mechanisms at different concentrations are largely unexplored in the same organic species. Herein, economical, low-flammable ethylene glycol (EG) is used as a model co-solvent in aqueous electrolytes to examine the relationship between its concentration, anode-stabilizing effect, and mechanism. Two maximal values are observed for the lifetime of Zn/Zn symmetric batteries under EG concentrations from 0.05 vol% to 48 vol%. Zn metal anodes can stably run for over 1700 h at a low EG content (0.25 vol%) and high EG content (40 vol%). Based on the complementary experimental and theoretical calculations, the enhancements in low- and high-content EG are ascribed to the specific surface adsorption for suppressed dendrite growth and the regulated solvation structure for inhibited side reactions, respectively. Intriguingly, a similar concentration-reliant bimodal phenomenon is observed in other low-flammable organic solvents (e.g., glycerol and dimethyl sulfoxide), thereby suggesting universality of this study and providing insight into electrolyte optimization.