Boosting Zinc Electrode Reversibility in Aqueous Electrolytes by Using Low‐Cost Antisolvents

• Published in: Angewandte Chemie International Edition Vol. 60; no. 13; pp. 7366 - 7375
• Main Authors: Hao, Junnan, Yuan, Libei, Ye, Chao, Chao, Dongliang, Davey, Kenneth, Guo, Zaiping, Qiao, Shi‐Zhang
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 22.03.2021
• Edition: International ed. in English
• Subjects: antisolvent; Aqueous electrolytes; Crystallization; dendrite-free; Dendrites; Dendritic structure; Deposition; Electrochemistry; Electrolytes; Electrolytic cells; Energy storage; Harsh environments; Light microscopy; Methanol; Optical microscopy; Pharmaceutical industry; Polyanilines; Sheaths; Side reactions; Solvation; Water activity; Zinc; Zinc sulfate; Zn ion battery; Zn2+ solvation; antisolvent; methanol; Zn2+ solvation; Zn ion battery; dendrite-free
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202016531

Antisolvent addition has been widely studied in crystallization in the pharmaceutical industries by breaking the solvation balance of the original solution. Here we report a similar antisolvent strategy to boost Zn reversibility via regulation of the electrolyte on a molecular level. By adding for example methanol into ZnSO4 electrolyte, the free water and coordinated water in Zn2+ solvation sheath gradually interact with the antisolvent, which minimizes water activity and weakens Zn2+ solvation. Concomitantly, dendrite‐free Zn deposition occurs via change in the deposition orientation, as evidenced by in situ optical microscopy. Zn reversibility is significantly boosted in antisolvent electrolyte of 50 % methanol by volume (Anti‐M‐50 %) even under harsh environments of −20 °C and 60 °C. Additionally, the suppressed side reactions and dendrite‐free Zn plating/stripping in Anti‐M‐50 % electrolyte significantly enhance performance of Zn/polyaniline coin and pouch cells. We demonstrate this low‐cost strategy can be readily generalized to other solvents, indicating its practical universality. Results will be of immediate interest and benefit to a range of researchers in electrochemistry and energy storage. Water activity and Zn2+ solvation in an ZnSO4 electrolyte are regulated by adding methanol as antisolvent. Methanol gradually interacts with the free and coordinated water in the Zn2+ solvation sheath in the electrolyte, to suppress side reactions and enhance the Zn2+ transference number. Concomitantly, Zn2+ deposition orientation is changed, resulting in dendrite‐free Zn deposition and boosted Zn reversibility.