Characterization of commercial thermal barrier materials to prevent thermal runaway propagation in large format lithium-ion cells

Abstract

In recent years, electric vehicles (EVs) have been rapidly introduced as an environmental measure. It is said, however, one of the challenges to accelerate their spread rests in how to increase their driving range. Recent safety regulations for EVs have been stringent in the wake of the potential risk of thermal runaway of battery packs. The battery pack is expected to withstand intense ignition during the event of thermal runaway while measures to suppress cell-to-cell thermal runaway propagation are also being considered as a mandatory safety standard. Thermal barrier materials are viable system-level solutions to mitigate cell-to-cell thermal runaway propagation via electrical, thermal, and fire insulation to meet regulatory safety needs. Among the various researched thermal barriers, only a few materials are commercially viable. Hence, this paper explores different commercially available thermal insulating materials that can be accommodated in battery packs. The materials selected combine key characteristics such as flame resistance, heat insulation, and thickness. Subsequently, we experimentally investigate the thermal and fire-risk properties of the selected thermal barrier materials via flame torch tests and compare their performances. Among the tested materials, a potential material has been used to further validate its performance in mitigating thermal runaway propagation in battery module/pack level overheating tests. Additionally, the comprehensive results of single-configuration thermal barrier characterization tests aided in combining different thermal barrier materials, which displayed better performance than single-configuration materials.