# A Review of Experimental and Numerical Studies of Lithium Ion Battery Fires
## 6 Modeling of LIBs
The commercial Li-ion (EiG ePLBF007a 7 Ah) pouch cells had a LFP cathode and a carbon-based anode. Several tests were conducted at different SOC, the experimental data associated with the LIB at 75% SOC were incorporated into the simulations. The complex structure of the pouch cells with the cathode and anode material being layered repeatedly provides difficulties in ascertaining the required thermal property variables such as thermal conductivity, density, and specific heat. In order to obtain reliable and accurate modeling results, precise thermal properties are required. The sheer complexity of the cells makes truly accurate modeling impractical and as such more generalized bulk values of the required thermal properties were used to model the propagative features of the LIBs. The results of the simulations show deficiencies in both the conjugate heat transfer and thermal models. Uncertain boundary conditions due to the lack of precise details around the test object in a fire scenario lead to less accuracy in the simulation. The boundary conditions are fundamental for computational simulations and inaccurate boundary conditions may lead to the divergence of the results or to the convergence of unrealistic results. [PERSON] et al. [145] demonstrated that the conjugate heat transfer model and the thermal model correlate well with the experimental data for the first four minutes; however, when the LIB seemingly goes into TR, the results of the modeling deviate from the experimental data significantly. They concluded that this deviation can be attributed in part to the thermal exposure being provided to only the underside of the cells in lieu of around the entire object. Uncertainty over the measured adiabatic surface temperature input values and the fact that the boundaries in a real case are not smooth and sharp, which creates a far more complex convective heat transfer between cells, are thought to contribute to the difference in the real and modelled scenarios. [PERSON] et al. [146] conducted three-dimensional (3D) TR modeling based on the energy balance equation. The model was built for a large-format prismatic LIB module to investigate TR propagation between adjacent cells. Penetration-induced TR experiments were conducted on large-format LIB modules to validate the 3D TR propagation models. The comparison between the triggering time to TR from one battery to the next for all six cells showed the model to correlate reasonably well with the experimental data. The 3D model also simulated temperature difference at the battery poles between the negative of battery \(i\) and the positive of battery \(i+1\) at the time when TR was triggered in battery \(i+1\). This essentially displays the heat transfer through the battery connector, as shown in Table 18. The values between the experimental and simulation are similar, validating the modeled scenario. As detailed in Table 18, there was only a maximum variation of 25 s in the duration of the TR propagation from cell 4 to cell 5; all others were within 15 s.  
The four mechanisms or changes proposed to prevent TR propagation within a large format battery module that were modeled clearly show the importance of fire modeling in helping researchers and engineers to better understand and design safer battery modules in regard to TR propagation. The modeling analysis determined the following points:  
* The TR triggering temperature is increased by modifying the separator;
* Total electric energy released during TR can be reduced by discharging the battery;
* By increasing the convection coefficient, the heat dissipation can be enhanced;