Thermal Behavior Analysis of Lithium Ion Cells Used in EVs and HEVs 2019-28-0163
The batteries for electric vehicles (EV) generate heat during discharging cycles. During these rapid discharge cycles the temperature of cell may increase above allowable limits. The high temperature of lithium ion cell is the primary factor affecting the cell performance and life. To develop efficient cooling mechanism for batteries, thermal behaviour of secondary cell is must know.
In this research, experimentally the thermal behaviour analysis of primary lithium ion cells for constant current discharge cycles with different current rates for each cycle is evaluated. The experiments were carried out at three discharge cycles of 1C, 2C and 3C rates and two battery chemistries of secondary cells have been considered for analysis. The temperature of cell was measured using thermal imager and increase in overall cell surface temperature at different discharge rates has been studied. An empirical relation for average surface temperature of cell as a function of time for different current rates have also been calculated which may have application in defining the discharge algorithms. The rates of internal heat generation in both type of cell chemistry have also been calculated experimentally. The analysis also helps in locating the high temperature zones in the cell which appear during discharge cycles.