Abstract: For efficient and reliable operation of lithium batteries, this paper investigates the thermal characteristics of lithium battery cells and modules under different multiplier discharges. Based on a one-dimensional heat generation model and a three-dimensional heat transfer model, an electrochemical-thermal coupling model for lithium batteries is established. The simulation is compared with the experimentally measured voltage and average temperature to verify the validity of the model. Meanwhile, the change rule of the battery temperature is analyzed from the perspective of heat generation. In addition, the influence of the connecting aluminum bars and both the positive and negative poles on the temperature field distribution of the battery module is explored from whether the bars and the poles generate heat. The results show that the larger the discharge multiplier, the faster the temperature rise of the battery surface. At a small discharge rate, reversible heat is the main factor affecting the change of the battery surface temperature. The heat generation of the bars and the poles has a large effect on the peak temperature and the location of the battery module, but almost no effect on its minimum temperature as well as the location. When the discharge multiplier is 2 C, the peak temperature difference reaches 6.5 ℃.