Measurement of Temperature Gradient (dT/dy) and Temperature Response (dT/dt) of a Prismatic Lithium-Ion Pouch Cell with LiFePO ₄ Cathode Material 2017-01-1207

Lithium-ion batteries, which are nowadays common in laptops, cell phones, toys, and other portable electronic devices, are also viewed as a most promising advanced technology for electric and hybrid electric vehicles (EVs and HEVs), but battery manufacturers and automakers must understand the performance of these batteries when they are scaled up to the large sizes needed for the propulsion of the vehicle. In addition, accurate thermo-physical property input is crucial to thermal modeling. Therefore, a designer must study the thermal characteristics of batteries for improvement in the design of a thermal management system and also for thermal modeling. This work presents a purely experimental thermal characterization in terms of measurement of the temperature gradient and temperature response of a lithium-ion battery utilizing a promising electrode material, LiFePO4, in a prismatic pouch configuration. The experiment was designed to obtain thermal images of the LiFePO4 cell to qualitatively evaluate the thermal behaviour and temperature distribution with IR (Infrared Radiation) imaging technique at different discharge rates of 2C, 3C, and 4C. A “FLIR System” Therma CAM model S60 IR camera is used in this work to obtain the thermal images. The measurements of the temperature rate of change (dT/dt) and temperature gradient (dT/dy) were performed along the lines traced (one near the anode, the second near the cathode, and the third at the center of the cell along the height of the cell) across the battery surface. The results, which were compared in magnitude to literature values, provided confirmation that non-uniform heat generation leads to non-uniform temperature distribution.