Lithium ion battery is considered as one of the most possible energy storage equipment for new energy vehicles (EV, HEV, etc.) because of the advantages of long cycle life, high power density and low self-discharge rate. However, under freezing condition high power battery suffers of significant performances losses. For example, they would suffer from significant power capability losses and poor rate performance, which would restrict the availability to delivery or to gain of high current in transient conditions. To evaluate those performance drawbacks and to make an efficient design, good mathematical models are required for system simulation especially for battery thermal management. In this paper, a three-dimensional homogenization thermal model of a 20 Ah prismatic lithium ion battery with LiFePO4 (LFP) cathode is described. This model particularly stresses on the high-ratio discharge property at low-temperature which could capture the shapes and dimensions of cell components and the spatial distributions of the temperatures. First, various discharge tests on one cell are carried out, and then, cell’s parameters and thermal characteristics are obtained. Ultimately, the three-dimensional thermal model for single-cell proposed is shown to be accurate by analyzing the simulation data and test results.