Abstract: The heat generation in a cell has a strong influence on performance and safe operation of Lithium-ion power battery. To study the temperature distribution and heat generation rate of a basic LiFePO4lithium ion battery at various galvanostatic discharge rates, an electro-thermal mathematical model was developed where the mass, charge,and thermal transport processes were considered, as well as the electrochemical reaction phenomena. The thermal characteristics predicted by the model agreed well with the experimental data. The results indicate that the reversible heat has a larger proportion of total heat generation under a lower discharge rate, while the ohmic heat is dominant under a higher discharge rate. A battery thermal management system is necessary under high discharge rate due to the higher temperature rise.