On the effect of gas generation on heat transfer during thermal runaway of pouch cells

Abstract

Lithium-ion batteries produce a vast amount of gases during decomposition reactions and thermal runaway. While the amount and composition of these gases has been investigated in the past, little is known about their impact on thermal transport inside the battery cell. Especially for pouch cells, which do not have a rigid housing, this becomes even more important in multi-cell scenarios since thermal propagation is governed by heat transfer. In this work, a simulation framework is presented that enhances the chemical single cell model by accounting for these thermal transport changes in gas producing pouch cells. It is validated by performing two battery cell propagation experiments in an autoclave. Besides the temperature measurement, the propagation time between the cells and the gas composition are analyzed and compared between simulation and experiment. Further, it is investigated how the application of an external pressing force impacts the heat transfer and thus the propagation behavior. In the given setup, the propagation time decreased from 37.2 s to 16.8 s with increasing pressing force.