A Competitive Solvation of Ternary Eutectic Electrolytes Tailoring the Electrode/Electrolyte Interphase for Lithium Metal Batteries

• Published in: ACS nano Vol. 16; no. 9; pp. 14558 - 14568
• Main Authors: Wu, Wanbao, Liang, Yihong, Li, Deping, Bo, Yiyang, Wu, Dong, Ci, Lijie, Li, Mingyu, Zhang, Jiaheng
• Format: Journal Article
• Language: English
• Published: American Chemical Society 27-09-2022
• Subjects: lithium metal battery; electrode/electrolyte interphase; competitive solvation mechanism; dendritic-free; ternary eutectic electrolyte; nonflammability
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/acsnano.2c05016

The development of electrolytes with high safety, high ionic conductivity, and the ability to inhibit lithium dendrites growth is crucial for the fabrication of high-energy-density lithium metal batteries. In this study, a ternary eutectic electrolyte is designed with LiTFSI (TFSI = bis­(trifluoromethanesulfonyl)­imide), butyrolactam (BL), and succinonitrile (SN). This electrolyte exhibits a high ion conductivity, nonflammability, and a wide electrochemical window. The competitive solvation effect among SN, BL, and Li+ reduces the viscosity and improves the stability of the eutectic electrolyte. The preferential coordination of BL toward Li+ facilitates the formation of stable solid electrolyte interphase films, leading to homogeneous and dendrite-free Li plating. As expected, the LiFePO4/Li cell with this ternary eutectic electrolyte delivers a high capacity retention of 90% after 500 cycles at 2 C and an average Coulombic efficiency of 99.8%. Moreover, Ni-rich LiNi0.8Co0.1Al0.1O2/Li and LiNi0.8Co0.1Mn0.1O2/Li cells based on the modified ternary eutectic electrolyte achieve an outstanding cycling performance. This study provides insights for understanding and designing better electrolytes for lithium metal batteries and analogous sodium/potassium metal batteries.