Exfoliation of graphite during electrochemical lithium insertion in ethylene carbonate-containing electrolytes

• Published in: Journal of the Electrochemical Society Vol. 151; no. 9; pp. A1383 - A1395
• Main Authors: SPAHR, Michael E, PALLADINO, Tiziana, WILHELM, Henri, WÜRSIG, Andreas, GOERS, Dietrich, BUQA, Hilmi, HOLZAPFEL, Michael, NOVAK, Petr
• Format: Journal Article
• Language: English
• Published: Pennington, NJ Electrochemical Society 2004
• Subjects: 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; Lithium battery; Graphite intercalation compounds; Organic electrolyte storage battery; Secondary cell; Electrode material; Metal nonmetal batteries; Specific capacity; Discharge charge cycle; Exfoliation; Electrical characteristic; Surface structure
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1775224

Post mortem scanning electron microscopy, X-ray diffraction analysis, and Raman spectroscopy were applied to study the exfoliation tendency of a high temperature-treated graphite negative electrode material during the first electrochemical lithium insertion in various carbonate electrolyte systems. Exfoliation of the heat-treated graphite electrode material was observed in propylene carbonate (PC)- and ethylene carbonate (EC)-containing electrolytes. Using acyclic carbonates and 1-fluoro ethylene carbonate, exfoliation of the graphite structure could be avoided. LiPF6 used as a conducting salt in the EC-based electrolyte increased the exfoliation tendency of the graphite material. Differential electrochemical mass spectrometry was performed to study the passivation of the untreated and heat-treated graphite surface during the first electrochemical Li+ insertion. The heat-treated graphite surface showed a reduced reactivity towards EC, which hindered the graphite surface passivation in EC-based electrolyte systems and led to the exfoliation of the graphite structure so far known only for PC-containing electrolytes.