Thermal characteristics of lithium ion secondary cells in high temperature environments using an accelerating rate calorimeter

Abstract

The analysis of the thermal behavior of Li-ion secondary cells in high temperature environments is one of the most important issues for the application of these batteries in electric vehicles. In this study, by using an accelerating rate calorimeter (ARC), we monitored the exothermic and thermal runaway behaviors of two lithium ion secondary cells using different cathode materials, lithium cobalt oxide (LCO) and lithium manganese oxide (LMO). Also, the internal resistance and open circuit voltage of the cells were recorded. As a result of the thermal runaway tests, it was found that the amount of heat released from the cell using LMO as the cathode material was lower when compared to the cell using LCO. In general, LMO exhibits a high thermal stability. This is mainly due to differences between the cathode materials. In addition, a sudden increase in the internal resistance and decrease in the open circuit voltage of the cells were detected, which seemed to be due to the shutting down of the cell separators. As already described, by combining the ARC tests and electrochemical measurements, we were able to identify the thermal and electrochemical characteristics, including the thermal runaway, based on the materials used in the Li-ion secondary cells.