Characterization of Fire and Smoke for Li-Ion Cells of Different Chemistries, Capacities and SOC

Lithium-ion batteries are used in various sectors from consumer devices to electic vehicles (EV) and large grid energy storage systems (ESS). The world has witnessed quite a few large fires recently in the EV as well as ESS installations causing a significant concern for the first responders and fire fighters. Parking garages as well as locations within buildings have facilities to park and charge the EV batteries and failures have led to thermal runaway, venting, fire and smoke. In parallel, ESS installations have had really large fires accompanied by deflagration when the ESS installation containers have been opened to external environments when first responders and fire fighters are called to respond to the fire. There is very little information in the literature on the composition of the gases released during thermal runaway of these li-ion batteries. The nature of the components in the fire and smoke and their toxicity and combustibility levels are also not fully understood. In an attempt to characterize the composition of the fire and smoke released as a result of thermal runaway, the Electrochemical Safety Research Institute (ESRI) at Underwriters Laboratories has conducted several studies in collaboration with the UL Fire Research team. Lithium-ion cells and modules (banks and batteries) of two different chemistries and capacities were studied under thermal runaway conditions to characterize the composition of the fire and smoke that accompanies the event. In addition to this, single cells of cylindrical and pouch format from a different set of manufacturers were also studied to understand the variation in fire and smoke composition with state of charge (SOC) and well as with two different rates of heating to trigger the cells into thermal runaway. Analysis of the composition of the fire and smoke provides an understanding of the combustibility and toxicity of the gases released. The background, results and challenges faced in this research work will be discussed in this presentation. Although there are many different manufacturers of li-ion cells and they vary in electrode combinations, separator, electrolyte combinations as well as in the other components that go into manufacturing the cells and batteries, the results provide insight into the major components that may be typically released and help in better preparing the response of first responders and fire fighters for the toxicity and combustibility hazards associated with these EV and ESS batteries.