Ionic liquid as electrostatic shielding additive for dendrite-free lithium metal battery

• Published in: Applied surface science Vol. 622; p. 156968
• Main Authors: Zhong, Jing, Wang, Zhixing, Wang, Siwu, Li, Xinhai, Guo, Huajun, Wang, Jiexi, Yan, Guochun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.06.2023
• Subjects: Electrolyte additive; Electrostatic shield; Ionic liquid; Lithium metal anode; Surface-enhanced Raman spectroscopy; Electrostatic shield; Electrolyte additive; Lithium metal anode; Surface-enhanced Raman spectroscopy; Ionic liquid
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2023.156968

[Display omitted] •0.5 M Pyr1(10)TFSI is introduced as a non-consuming electrolyte additive and uniform lithium deposition by electrostatic shielding mechanism.•The adsorption of Pyr1(10)+ cation is explored by Surface-enhanced Raman spectroscopy and EIS.•Outstanding cyclability is demonstrated in LiFePO4||Li full cells with low N/P radio. Lithium (Li) metal anodes have attracted much attention as their high specific capacity and low electrochemical potential significantly boost the energy density of secondary batteries. Nonetheless, the uncontrolled growth of Li dendrites causing a poor cycle capability restricts the commercialization of Li metal batteries. Herein, an ionic liquid with a long aliphatic chain (N-methyl-N-decyl pyrrolidinium (Pyr1(10)+) bis(trifluoromethanesulphonyl)imide (TFSI−)) is introduced as a non-consuming electrostatic shielding additive into the ether-based electrolyte. The admirable compatibility of Pyr1(10)+ cation with Li metal is verified via electrochemical analysis, and the adsorption of Pyr1(10)+ on the Li-metal/electrolyte interface is confirmed by Surface-enhanced Raman spectroscopy technique. Through redistributing the Li ions on the surface of Li metal, the growth of Li dendrites is suppressed, so as to improve the cycling performance of Li metal anodes in symmetric cells, asymmetric cells and Li||LiFePO4 full cells with low N/P ratio (3:1). This study provides new insights into revealing the electrostatic shielding mechanism of regulating Li metal deposition and prolonging the long-term cycling.