Electrochemical-calorimetric studies on different lithium-ion cells

The lithium-ion batteries used in current electric vehicles evidently have reserves. When the capacity in each cell was optimally utilized, more energy could be put in and delivered again. Thus, the driving range of electric vehicles could be significantly increased. In this work, commercial lithium-ion pouch cells were cycled at varying C-rates under isoperibolic and adiabatic conditions in an accelerating rate calorimeter (ARC) with external battery cycler to investigate their performance and their thermal behavior. A thermal camera was also used to investigate the heat effects and the local temperature distribution during cycling in more details. Different factors that have influence on the performance of energy storage such as temperature, charging/discharging current and state of charge (SOC) have been studied. The isoperibolic investigations were performed at specific temperatures in the range from 25 to 60 °C. The results show that the applied environmental temperature did not largely influence the battery thermal behavior. Both isoperibolic and adiabatic tests were performed at different charging/discharging rates in the range from C/4 to 3C. The results show a considerable temperature rise with increasing rate. Additionally, the heat capacities and the calorimeter constant were determined to calculate the total generated heat during cycling