This thesis aims at the identification and modeling of the underlying phenomena that trigger thermal runaway in lithium-ion batteries. While a great amount of research has been done on simulation of lithium-ion battery's normal operation and thermal runaway separately, very few have attempted to link both the conditions. This study can be regarded as a stepping stone to the development of robust battery management systems that can predict whether the lithium-ion battery will go into thermal runaway or not. In the first two chapters, a brief introduction and analyses of different modeling techniques are presented. The next chapter pushes the physics-based P2D model to thermal abuse conditions and specifies a few modifications that can improve the scope of its validity. Since the study in this area is limited, a simple first-order model using an equivalent circuit is chosen to simulate battery operation at relatively high temperatures. The fourth chapter deals with the parameterization and the validation of the circuit model. At the end, the model output is compared to experimental data. The results show that the thermal response of the battery can be captured by this simple model, however, some steps need to be taken for accurate parameterization. Some model modifications are added to increase the fidelity of the current model. A case with thermal runaway is also presented where the different regions of battery degradation are specified. The insights provided can be utilized to further tune the circuit model.