The thermal management of battery systems is crucial to ensure their safety and performance. Electrochemical reactions within a lithium-ion (li-ion) battery pack during charging and discharging generate significant heat, which, if not properly managed, can lead to thermal runaway, fire, or explosion. This study uses a multi-scale, multi-dimensional electrochemical thermal model to investigate the heat generation and thermal behavior in a 23Ah battery pack composed of two prismatic cells. The simulation, carried out in ANSYS Fluent, considers various discharge rates (1C, 3C, 5C, 10C) and examines the effects of electrode thickness and particle size on the thermal and electrical performance. Key findings include how variations in discharge rate influence heat generation and temperature distribution across the battery, as well as how the electrode properties impact the overall thermal management. This model offers insights into improving battery safety and performance through optimized thermal management strategies.