Experimental and Simulation Studies on the Thermal Characteristics of Large‐Capacity Square Lithium‐Ion Batteries with Low‐Temperature Discharge

As the capacity of lithium‐ion batteries decays severely at low temperatures, it is important to study the electrochemical and thermal properties of lithium‐ion batteries at low temperatures. Herein, a large‐capacity prismatic lithium‐ion battery is selected to carry out experiments to study the electrothermal characteristics of the battery in different temperatures (25, 0, −10, and −20 °C). Second, a pseudo‐3D electrochemical–thermal coupling model is established and the validity of the model is verified. Finally, this article analyzes the influence of ambient temperature on the thermal characteristics of the battery during discharge. The results show that the battery discharge capacity gradually decreases with the decrease in the ambient temperature. At −20 °C, the discharged electricity is 66.51% of that at room temperature. At the same time, as the ambient temperature drops, the temperature rise on the surface of the battery increases during the discharge process, and at −20 °C, the temperature rise can reach 3.86 times than that at normal temperature. In addition, the change in reversible heat percentage is negatively correlated with the discharge rate and positively correlated with the battery temperature, while the effect of the discharge rate on irreversible heat is greater than that of ambient temperature.