Prediction of Temperature in a Penetrated Lithium-Ion Pouch Cell Using a Multi-Physics Model

Abstract

Recently safety studies have been actively conducted for large capacity lithium-ion batteries (LIB) used in various industry fields, not only electric vehicle (EV) but energy storage system (ESS) and etc. However, these large LIB cells more can bring critically dangerous explosive accidents in larger scales than small LIB cells. Thermal runaway, the common event before the LIB explosion, is caused by many reasons such as overcharge, internal and external short circuits and self-reaction heating at high temperature. Many numerical studies have been conducted to thermal behaviors of LIBs for safety. However, experimental tests of the safety incidents are usually hard to be reproduced and controllable so that experimental data has been lacked. In this situation, multi-physical models can produce electrochemical responses and electrical- thermal behaviors of LIBs which experience the safety problems. Using numerical models, thermal risks in various short-circuit circumstances can be predicted. In this study, we will represent an electric- electrochemical-thermal (EECT) model to estimate thermal behaviors of LIB cells in internal short circuit situations. This multi- physics model considers charge conservation, thermal energy conservation in cell volumes and also calculates electrochemical reactions at active electrodes using the pseudo-2-dimension method (P2D). The model calculates electrical current paths through the nail penetrating the cell and Ohmic heat generated by the electric currents. Using the EECT model, a large capacity LIB cell was simulated for a nail penetration case. The design of the cell was chosen to be similar to that of the cells in the industrial fields like energy storage system (ESS) or EV. The cell has about 20Ah capacity and graphite (LiC6) and layered nickel metal oxide (LiNi0.5Co0.2Mn0.3O2, NCM523). The size of the nail was 5mm by 5mm and made of still. Also, parametric studies about nail size, location, and state of charge (SOC) of the cell were conducted and the parametric data was used for providing the safety guidelines at the short-circuit situations. Figure 1