In this paper, three different empirical modeling approaches for the heat release during a battery cell thermal runaway (TR) are analyzed and compared with regard to their suitability for TR and TR propagation simulation. Therefore, the so called autoclave calorimetry experiment conducted with a prismatic lithium-ion battery (>60 Ah) is modeled within the 3D-CFD framework of Simcenter Star-CCM+® and the simulation results are compared to the experiments. In addition, the influence of critical parameters such as mass loss during TR, the jelly roll’s specific heat capacity and thermal conductivity is analyzed. All of the three modeling approaches are able to reproduce the experimental results with high accuracy, but there are significant differences regarding computational effort. Furthermore, it is crucial to consider that the mass loss during TR and both specific heat capacity as well as thermal conductivity of the jelly roll have a significant influence on the simulation results. The advantages and disadvantages of each modeling approach pointed out in this study and the identification of crucial modeling parameters contribute to the improvement of both TR as well as TR propagation simulation and help researchers or engineers to choose a suitable model to design a safer battery pack.

A total number of 25 different types of prismatic lithium-ion cells with a capacity between 8 and 145 Ah are examined in an autoclave calorimetry experiment in order to analyze their behavior during thermal runaway (TR). The safety relevant parameters such as mass loss, venting gas production and heat generation during TR are determined in two experiments per cell type and the results are compared to literature. An approximately linear dependency of the three parameters on the cell capacity is observed and hence correlations are derived. Due to the wide range in cell properties the correlations can be used as input for simulations as well as to predict the behavior of future battery cells within the property range of those tested and therefore contribute to the design of a safer battery pack.

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