Thermal Imaging of a Li-Ion Battery for the Estimation of the Thermal Parameters and Instantaneous Heat Dissipated

The electrochemical performance of a lithium-ionbattery is strongly affected by the temperature.During charge and discharge cycles, batteries aresubjected to an increment of temperature that can accelerateaging and loss of efficiency if critical values are reached.Knowing the thermal parameters that affect the heatexchange between the battery surface and the surroundingenvironment (air, cooling fins, plates, etc.) is fundamentalto their thermal management. In this work, thermal imagingis applied to a laminated lithium-polymers battery as a noninvasivetemperature-indication method. Measurements aretaken during the discharge phase and the following coolingdown until the battery reaches the ambient temperature.The 2d images are used to analyze the homogeneity of thetemperature distribution on the battery surface. Then, experimentalresults are coupled with mathematical correlations.The derivation of the instantaneous heat generated in thebattery and Newton's cooling law in transient conditions areused to estimate two main thermal parameters, as theconvective heat transfer coefficient and the specific heatcapacity, and then to calculate the heat generated by thebattery. The experimentally-based derivation of the abovementionedthermal parameters will be useful in advancedthermal models for the design of batteries and batterycooling systems.