Procedures for Experimental Characterization of Thermal Properties in Li-Ion Battery Modules and Parameters Identification for Thermal Models

Concerns about climate change have significantly accelerated the process of vehicle electrification to improve the sustainability of the transportation sector. Increasing the adoption of electrified vehicles is closely tied to the advancement of reliable energy storage systems, with lithium-ion batteries currently standing as the most widely employed technology. One of the key technical challenges for reliability and durability of battery packs is the ability to accurately predict and control the temperature of the cells and temperature gradient between cells inside the pack. For this reason, accurate models are required to predict and control the cell temperature during driving and charging operations. This work presents a set of procedures tailored to characterize and measure the thermal properties in li-ion cells and modules. Thermal parameters such as the specific heat capacity, the heat conduction coefficient through the cell thickness and the cell-to-cell heat transfer coefficient are obtained via dedicated experimental setups and test protocols. The tests allow one to estimate the overall thermal resistance in the case of cell-to-cell contact, accounting to conduction and contact resistance. The experimental procedures are utilized to inform the calibration process of thermal models predicting the heat generation, dissipation and temperature distribution in large format li-ion cells and modules. The identified parameters are validated using a different set of data with an electro-thermal model. Validation of the procedure against experimental data confirms the ability of the model to predict well the temperature of the cells.