Thermo-electric behavior analysis and coupled model characterization of 21,700 cylindrical ternary lithium batteries affected by cyclic aging

In order to achieve a balance between the precision of thermal behavior simulation of lithium batteries affected by cyclic aging and the practicality of engineering popularization and application, a simple degraded battery thermal model needs to be constructed. In this article, a characterization approach for the coupled battery thermo-electric model affected by cyclic aging is designed. This method is suitable for simulating the thermal behavior of lithium degraded batteries with different materials and shapes under different environmental temperatures. This paper introduces the idea by taking the 21,700 cylindrical ternary lithium batteries as an example. Firstly, based on the interaction mechanism between the growth of the solid electrolyte interface film on the battery negative electrode surface at the microscopic level and the battery thermoelectric coupling characteristics at the macro level, the paper constructs a theoretical model of the degraded battery. Further, it conducts experiments to analyze the battery charging and discharging behaviors in the process of cyclic aging. Based on experimental data, this paper conducts multiple fitting calculations to extract essential modeling parameters. Subsequently, this paper builds the battery physical model in the simulation software based on the above modeling parameters. It applies the battery physical model to simulate the thermal characteristics and temperature field. Then, it conducts experiments to demonstrate the precision of the model. This paper uses the infrared imaging technique to visualize and analyze temperature field variations on the battery surface. And it uses thermocouple temperature sensors to capture the battery surface temperature changes. The simulation results are compared with the experimental data, the errors are less than 5 %. Compared with other existing battery thermal models, the model of this paper is more suitable for engineering popularization and application of thermal behavior simulation of lithium batteries affected by cyclic aging.