Effects of Room Ionic Liquid as Solute on the Electrolyte Solution Structure and Electrochemical Performances in Ethylene Carbonate-Based Electrolyte. Issue 16 (1st January 2018)

• Record Type: Journal Article
• Authors: Gao, Ximei; Zhu, Guobin; Qu, Qunting; Liu, Gao; Battaglia, Vincent S.; Zheng, Honghe
• Is Part Of: Journal of the Electrochemical Society. Volume 165:Issue 16(2018)
• Page Start: A3844
• Page End: A3853
• Publication Date: 2018-01-01
• Subjects: Batteries - Lithium -- electrolyte -- ionic liquid -- Lithium ion batteries; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0491916jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Room ionic liquid N-allyl-N-methylpiperidinium bis(trifuoromethansulfonyl)imide (PP13 * TFSI) was adopted as a solute to partly substitute LiPF6 in concentrated ethylene carbonate (EC) based electrolyte (1.8 mol L −1 LiPF6 /EC). Raman and FTIR spectroscopic studies revealed that the electrolyte solution structure was adjusted in the presence of PP13 * TFSI ionic liquid. Solvation number of Li + cation could be effectively regulated by the competitive coordination of PP13 * + and Li + with EC molecules. More importantly, the appearance of TFSI − anion brings about a different coordinating environment of PF6 − anion in virtue of the stronger association capability of the TFSI − than that of PF6 −, which resulted in a content regulation of the SEI components between Li2 CO3 and LiF, finally contributing to a remarkable cycle life of graphite/Li cell comprising electrolyte with PP13 * TFSI. The optimized molar ratio between LiPF6 salt and PP13 * TFSI ionic liquid was obtained to be 3:1. Differential scanning calorimetry (DSC) confirmed significantly widened liquid range in the EC-based electrolytes with PP13 * TFSI substitution. This work will provide a new insight and thinking on the application of room ionic liquid.