A Study of Perfluorocarboxylate Ester Solvents for Lithium Ion Battery Electrolytes

Abstract

Several high-purity methyl perfluorocarboxylates were prepared (>99.5% purity by mole) and investigated as potential fluorine-rich electrolyte solvents in Li-ion batteries. the most conductive electrolyte, 0.1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in dimethyl perfluoroglutarate (PF5M2) (ionic conductivity = 1.87 × 10-2 mS cm-1), is investigated in Si thin-film half-cells. the solid-electrolyte-interphase (SEI) formed by the PF5M2 electrolyte is composed of similar organic and inorganic moieties and at comparable concentrations as those formed by ethylene carbonate/dimethyl carbonate electrolytes containing LiPF6 and LiTFSI salts. However, the SEI formed by the PF5M2 electrolyte undergoes reversible electrochemical defluorination, contributing to the reversible capacity of the cell and compensating in part for capacity fade in the Si electrode. While far from ideal these electrolytes provide an opportunity to further develop predictions of suitable fluorinated molecules for use in battery solvents.

Department(s)

Chemistry

Keywords and Phrases

Electric batteries; Electrolytes; Ethylene; Lithium; Lithium alloys; Lithium compounds; Seebeck effect; Solid electrolytes; Solvents; Thin films; Bis(trifluoromethane sulfonyl)imide; Carbonate electrolytes; Fluorinated molecules; LiTFSI; Perfluorocarboxylates; SEI; Silicon thin film; Solid electrolyte interphase; Lithium-ion batteries; Fluorinated electrolyte; LiTFSI; SEI; Silicon thin-film

International Standard Serial Number (ISSN)

0378-7753

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2015 Elsevier, All rights reserved.

Publication Date

01 Dec 2015

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