Simplified Thermal Runaway Model for Assisting the Design of a Novel Safe Li-Ion Battery Pack

Abstract

This paper presents a simplified thermal runaway model (FEM) used to guide the design of a novel battery pack designed to resist thermal runaway propagation passively. The model is based on the heat equation for a 2D geometry with a heat generation term based on the maximum amount of energy measured using a custom-made calorimeter. The model was validated against experimental data using a 48-cell subscale of a full-scale battery pack for three different runs with three trigger cells with Internal Short Circuit Devices (ISCD) implanted in the separators. One trigger cell was placed at the edge, one placed in the middle, surrounded by six cells, and one placed in one corner of the subscale pack. It was shown that by simplifying the geometry and looking at the complex thermal runaway propagation mechanism only from a thermal perspective (no electrochemical reactions or fluid flow), the model predicted the experimental data with good precision. Furthermore, such a model was used to validate some experimental observations, which indicated the practicality of such a simplified design tool.