ABSTRACT Isothermal microcalorimetry is a simple method of determining the effect an electrolyte additive or additive combination has on the parasitic reactions occurring in a lithium-ion battery as a function of state of charge. In this study, high resolution isothermal microcalorimetry using a TAM III equipped with 12 microcalorimeters is used to measure and quantitatively compare the heat flow of lithium-ion batteries that only vary in concentration of electrolyte additive. In this case, with all other sources being identical, the measured difference in heat flow is a direct result of the difference in parasitic heat due to the additive. This is done as a function of state of charge, providing a simple and quick method of determining exactly where and to what extent the electrolyte additive is reducing parasitic reactions. As a demonstrative example, the effect of varying concentrations of vinylene carbonate (VC) on a LiCoO2/graphite cell is examined. It is shown that the presence of VC reduces parasitic reactions above 3.9 V, and continues to reduce these reactions with increasing state of charge. The method and data presented herein have been published (Reference 1) and are reproduced with permission. Copyright 2013, The Electrochemical Society
Keywords: Isothermal calorimetry, TAM, heat flow, lithium-ion batteries, electrolyte additives, parasitic heat MCAPN-2014-3a