Thermophysical parameter identification for prismatic lithium-ion batteries through thermal excitation and response analysis

The values of battery thermophysical parameters exert a direct influence on the precision of the finite element model (FEM), which affects the efficacy of the designed battery thermal management system therefore. The reliance on costly instruments and the necessity for complex experimental procedures present significant obstacles to the acquisition of battery thermophysical parameters. This work identifies the heat capacity and two anisotropic thermal conductivity coefficients for a prismatic lithium-ion battery. Firstly, the battery is wrapped in cotton to create a near-adiabatic experimental environment. The specific heat capacity of the battery is then measured under these conditions. Subsequently, heating films of varying shapes are employed to heat the battery in the aforementioned near-adiabatic environment, thereby decoupling the heat transfer in different dimensions. The influence of the battery shell on the resulting measurements is taken into account when the thermal conductivity is solved by the heat excitation response analysis method. Finally, the measured specific heat capacity and anisotropic thermal conductivity are incorporated into the FEM to facilitate further simulation of the thermal behavior of the battery during 1C constant current discharge. The physical experiment used two distinct platforms, namely a single battery cell and a 5-series-connected battery pack, which were constructed separately. In both cases, the maximum discrepancy between the simulations and the measurements is less than 0.8°C, and the mean error not exceeding 0.3°C. The temperature profiles of the simulated and measured data demonstrate a high degree of similarity in both scenarios, indicating that the thermophysical parameters are considered accurate. The main contribution of this paper is the convenient acquisition of accurate thermophysical parameters of prismatic batteries through a novel experimental setup and the thermal excitation response analysis method. The research narrows the gap between accurate thermophysical parameter acquisition and expensive experimental equipment.