pH‐Triggered Molecular Switch Toward Texture‐Regulated Zn Anode

• Published in: Angewandte Chemie International Edition Vol. 62; no. 17; pp. e202301570 - n/a
• Main Authors: Zhang, Shao‐Jian, Hao, Junnan, Zhu, Yilong, Li, Huan, Lin, Zhan, Qiao, Shi‐Zhang
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 17.04.2023
• Edition: International ed. in English
• Subjects: Alkalinity; Aqueous solutions; Bonding strength; Dynamic Interface; Electrodes; High Zn DOD; Hydrogen evolution; Iodine; Low Temperature; Modulation; Molecular machines; Molecular Switch; Texture; Zinc; Zinc chloride; Zn-Ion Battery; γ-Hydroxybutyric acid; Molecular Switch; Low Temperature; Zn-Ion Battery; High Zn DOD; Dynamic Interface
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202301570

Zn electrodes in aqueous media exhibit an unstable Zn/electrolyte interface due to severe parasitic reactions and dendrite formation. Here, a dynamic Zn interface modulation based on the molecular switch strategy is reported by hiring γ‐butyrolactone (GBL) in ZnCl2/H2O electrolyte. During Zn plating, the increased interfacial alkalinity triggers molecular switch from GBL to γ‐hydroxybutyrate (GHB). GHB strongly anchors on Zn surface via triple Zn−O bonding, leading to suppressive hydrogen evolution and texture‐regulated Zn morphology. Upon Zn stripping, the fluctuant pH turns the molecular switch reaction off through the cyclization of GHB to GBL. This dynamic molecular switch strategy enables high Zn reversibility with Coulombic efficiency of 99.8 % and Zn||iodine batteries with high‐cyclability under high Zn depth of discharge (50 %). This study demonstrates the importance of dynamic modulation for Zn electrode and realizes the reversible molecular switch strategy to enhance its reversibility. Depending on the periodic pH evolution during Zn plating/stripping, a pH‐triggered molecular switch with reversible transformation between γ‐butyrolactone and γ‐hydroxybutyrate is applied to dynamically modulate the Zn/electrolyte interface. This molecular switch strategy results in texture‐regulated Zn plating, suppressed hydrogen evolution, and excellent Zn reversibility even under high depth of discharge.