Co-Solvent Electrolyte Engineering for Stable Anode-Free Zinc Metal Batteries

Abstract
Anode-free metal batteries can in principle offer higher energy density, but this requires them to have extraordinary Coulombic efficiency (>99.7%). Although Zn-based metal batteries are promising for stationary storage, the parasitic side reactions make anode-free batteries difficult to achieve in practice. In this work, a salting-in-effect-induced hybrid electrolyte is proposed as an effective strategy that enables both a highly reversible Zn anode and good stability and compatibility toward various cathodes. The as-prepared electrolyte can also work well under a wide temperature range (i.e., from −20 to 50 °C). It is demonstrated that in the presence of propylene carbonate, triflate anions are involved in the Zn2+ solvation sheath structure, even at a low salt concentration (2.14 M). The unique solvation structure results in the reduction of anions, thus forming a hydrophobic solid electrolyte interphase. The waterproof interphase along with the decreased water activity in the hybrid electrolyte effectively prevents side reactions, thus ensuring a stable Zn anode with an unprecedented Coulombic efficiency (99.93% over 500 cycles at 1 mA cm–2). More importantly, we design an anode-free Zn metal battery that exhibits excellent cycling stability (80% capacity retention after 275 cycles at 0.5 mA cm–2). This work provides a universal strategy to design co-solvent electrolytes for anode-free Zn metal batteries

Citation
Ming, F., Zhu, Y., Huang, G., Emwas, A.-H., Liang, H., Cui, Y., & Alshareef, H. N. (2022). Co-Solvent Electrolyte Engineering for Stable Anode-Free Zinc Metal Batteries. Journal of the American Chemical Society. https://doi.org/10.1021/jacs.1c12764

Acknowledgements
Supported by the King Abdullah University of Science and Technology (KAUST). Authors appreciate Dr. Jian Yin, Dr. Zhiming Zhao, and Yongjiu Lei for their kind help and insightful discussion. Authors also thank the Advanced Nanofabrication, Imaging, and Characterization Laboratory at KAUST for their excellent support

Publisher
American Chemical Society (ACS)

Journal
Journal of the American Chemical Society

DOI
10.1021/jacs.1c12764

Additional Links
https://pubs.acs.org/doi/10.1021/jacs.1c12764https://www.osti.gov/biblio/1876886

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