Highly Reversible Aqueous Zinc Batteries enabled by Zincophilic–Zincophobic Interfacial Layers and Interrupted Hydrogen‐Bond Electrolytes. (16th July 2021)

• Record Type: Journal Article
• Authors: Cao, Longsheng; Li, Dan; Soto, Fernando A.; Ponce, Victor; Zhang, Bao; Ma, Lu; Deng, Tao; Seminario, Jorge M.; Hu, Enyuan; Yang, Xiao‐Qing; Balbuena, Perla B.; Wang, Chunsheng
• Is Part Of: Angewandte Chemie. Volume 133:Number 34(2021)
• Page Start: 18993
• Page End: 18999
• Publication Date: 2021-07-16
• Subjects: aqueous zinc batteries -- hydrogen bonds -- low temperature -- salt precipitation -- zincophilic–zincophobic interfacial bilayer; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202107378
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Aqueous Zn batteries promise high energy density but suffer from Zn dendritic growth and poor low‐temperature performance. Here, we overcome both challenges by using an eutectic 7.6 m ZnCl2 aqueous electrolyte with 0.05 m SnCl2 additive, which in situ forms a zincophilic/zincophobic Sn/Zn5 (OH)8 Cl2 ⋅H2 O bilayer interphase and enables low temperature operation. Zincophilic Sn decreases Zn plating/stripping overpotential and promotes uniform Zn plating, while zincophobic Zn5 (OH)8 Cl2 ⋅H2 O top‐layer suppresses Zn dendrite growth. The eutectic electrolyte has a high ionic conductivity of ≈0.8 mS cm −1 even at −70 °C due to the distortion of hydrogen bond network by solvated Zn 2+ and Cl − . The eutectic electrolyte enables Zn∥Ti half‐cell a high Coulombic efficiency (CE) of >99.7 % for 200 cycles and Zn∥Zn cell steady charge/discharge for 500 h with a low overpotential of 8 mV at 3 mA cm −2 . Practically, Zn∥VOPO4 batteries maintain >95 % capacity with a CE of >99.9 % for 200 cycles at −50 °C, and retain ≈30 % capacity at −70 °C of that at 20 °C. Abstract : A highly reversible Zn anode working at low temperature is achieved by introducing SnCl2 into eutectic ZnCl2 aqueous electrolyte to form a zincophilic–zincophobic interfacial layer on the Zn anode in situ. The bottom layer of Sn facilitates uniform Zn deposition, while the top layer of zincophobic Zn5 (OH)8 Cl2 H2 O facilitates Zn 2+ diffusion and avoids Zn dendrites. The eutectic composition enhances the low temperature conductivity.