Thermal characterization of pouch cell using infrared thermography and electrochemical modelling for the Design of Effective Battery Thermal Management System

Abstract

Lithium-ion (Li-ion) cells are the optimal choice of energy storage for battery electric vehicles. As the Li-ion cells must operate in a temperature range of 15–45 °C for optimal performance and life, thermal control of the cells is paramount. The study uses infrared imaging to investigate the temperature dynamics of two lithium-ion pouch cells with two energy capacities, 60 Ah and 20 Ah under different operational scenarios with natural convection. Experimental analysis conducted at ambient temperatures of 27 °C, 35 °C, and 40 °C reveals the necessity of cooling for the 20 Ah cell at temperatures exceeding 40 °C and C-rates beyond 1C. Similarly, thermal management is recommended for the 60 Ah cell at ambient temperatures of 35 °C and above, as temperatures surpass the 45 °C desirable threshold during charging and discharging rates of 1C and higher. Further studies are concentrated on the 60 Ah cell due to its increased cooling demands in comparison to the 20 Ah cell. The 60 Ah cell is modelled using NTGK and ECM electrochemical models and validated against experimental data, showing a good agreement within ±10% between both models and the experimental study. Finally, numerical simulations explain the efficacy of localized cooling with forced convection of liquid and performance metrics are introduced to evaluate the cooling efficiency of design configurations. Based on performance metrics, the T-shaped cold plate design, with an inlet coolant temperature of 30 °C, achieved the highest performance index of 1.13. This design notably decreased the maximum temperature and maximum temperature difference by 41.8% and 31.8%, respectively, compared to natural convection. This improvement is observed during the discharge of 60 Ah cell at 2C in a 40 °C environment, where the cell demands substantial cooling measures. Therefore, implementing localized cooling for the cell demonstrates its effectiveness in regulating temperature increase, leading to a significant decrease in the infrastructure requirements and weight of the thermal management system.