Accelerating rate calorimetry studies of the reactions between ionic liquids and charged lithium ion battery electrode materials

• Published in: Electrochimica acta Vol. 52; no. 22; pp. 6346 - 6352
• Main Authors: Wang, Yadong, Zaghib, K., Guerfi, A., Bazito, Fernanda F.C., Torresi, Roberto M., Dahn, J.R.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 30.06.2007; Elsevier
• Subjects: Accelerating rate calorimetry; Applied sciences; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Ionic liquids; Lithium-ion batteries; Safety; Lithium-ion batteries; Ionic liquids; Accelerating rate calorimetry; Safety; Viscosity; Electrical conductivity; Secondary cell; Electrode material; Ionic liquid; Electrodes; Self heating; Lithion ion batteries; Thermal analysis; Lithium Hexafluophosphates; Rheological properties
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2007.04.067

Using accelerating rate calorimetry (ARC), the reactivity between six ionic liquids (with and without added LiPF 6) and charged electrode materials is compared to the reactivity of standard carbonate-based solvents and electrolytes with the same electrode materials. The charged electrode materials used were Li 1Si, Li 7Ti 4O 12 and Li 0.45CoO 2. The experiments showed that not all ionic liquids are safer than conventional electrolytes/solvents. Of the six ionic liquids tested, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI) shows the worst safety properties, and is much worse than conventional electrolyte. 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI) and 1-propyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide (Py13-FSI) show similar reactivity to carbonate-based electrolyte. The three ionic liquids 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide (BMMI-TFSI), 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide (Pp14-TFSI) and N-trimethyl- N-butylammonium bis(trifluoromethanesulfonyl)imide (TMBA-TFSI) show similar reactivity and are much safer than the conventional carbonate-based electrolyte. A comparison of the reactivity of ionic liquids with common anions and cations shows that ionic liquids with TFSI − are safer than those with FSI −, and liquids with EMI + are worse than those with BMMI +, Py13 +, Pp14 + and TMBA +.