(Digital Presentation) Experimental Investigation of Thermal Runaway of Single 21700 Li-Ion Cell and Runaway Propagation in a Battery Module

Abstract

Li-ion battery is an integral part for the electric or hybrid electric vehicles, as they provide high energy density and power density with extended cycle-life compared to their closest rivals, Ni-MH batteries [1]. As the Li-ion batteries gained significant success in the automotive sector, safety issues, pertaining to the fire and explosion accidents caused by thermal runaway (TR) have become a critical issue obstructing their applications. Therefore, the Li-ion battery thermal runaway has attracted an increasing attention of the research community worldwide. Thermal runaway is a self-accelerated degradation process of Li-ion batteries, [2] it can be brought by abuse [3] or internal cell failure due to defects [4]. During the TR, a significant amount of burnable and harmful gas and a large amount of heat are generated, which substantially increase the temperature of batteries [5]. Currently, most of the research work on the TR characteristics are conducted under different triggering modes at the cell level. However, the research on the large lithium battery pack is quite scarce. Therefore, several important issues need to be identified to reveal the critical conditions of the fire propagation, and precisely predict the fire risk of Li-ion battery pack fire.In this work, thermal failure experiments were performed using commercial cylindrical 21700 Li-ion single cell and a module by external heating, to analyze the casing rupture and the TR propagation behaviors in the pack based on the fire test apparatus. The critical parameters including the temperature, and heat release rate will be carefully analyzed to reveal the fire propagation hazards of battery packs.