Exploring the Energetics of the Lithium Ion-Organic Carbonate Interaction: A Temperature-Dependent FTIR Study

Tuesday, 30 May 2017
Grand Ballroom (Hilton New Orleans Riverside)
K. Woodard, K. D. Fulfer, and D. G. Kuroda (Louisiana State University)
Lithium ion batteries are now essential to the portable energy storage industry. However, this technology still faces many problems associated with safety and energy storage density. While the energy storage density is related to all components of the battery, its safety concerns are mostly associated with the lithium ion electrolyte. Typical lithium ion electrolytes are composed of a lithium salt in a mixture of organic carbonate solvents of both linear and cyclic structure. Specifically, the industry standard, referred to as the generation 2 lithium ion battery electrolyte, is composed of ~1M lithium hexafluorophosphate salt in a mixed ethylene carbonate/ethyl methyl carbonate solvent at a volume ratio of 3:7 and has the highest conductivity reported for a carbonate-based electrolyte so far. However, the underlying reasons for realizing higher conductivity and better electrochemical cycling in specific carbonate mixtures are unknown. By further characterizing the interactions between the lithium ion and the organic carbonates, a more complete understanding of these electrolytes and how they function within the battery can be obtained. In this study, we have characterized the energetics of the lithium ion-carbonate interaction for several carbonates, both linear and cyclic in structure using temperature-dependent infrared spectroscopy. Our studies show new insights into the interplay between the energetics of lithium solvation.