(17b) Explosion Hazards Due to Failures of Lithium-Ion Batteries

Explosion hazards due to failures of Lithium-Ion Batteries

The failure modes of lithium-ion cells have been extensively studied for applications where the total energy of the battery system is typically below 100 Wh.  As lithium-ion cells and systems become larger and more ubiquitous in their use in automotive and vehicular applications, some failure modes that were rare or non-existent in smaller systems are becoming more common.  One potentially hazardous failure mode seen in large lithium-ion systems occurs when flammable gases are emitted from a lithium-ion cell, reach the lower explosion limit in a confined space like within the chassis of the vehicle or inside a garage or basement and are ignited by electrical activity or the cells themselves. If this scenario occurs, the confined space can become overpressurized, potentially resulting in an explosion and severe damage to life and property.

With the spread of Lithium ion battery technology into areas like backup power storage, electric and hybrid vehicles and grid stabilization, the safety aspects of using these large energy storage battery packs, especially those related to fires and explosions protection are a significant challenge to address. This paper describes and characterizes the combustion and explosion hazards that can occur when a lithium ion battery pack fails and goes into thermal runaway in an enclosed space. Metrics such as gas composition, maximum overpressure, rate of pressure rise, flammability limits and limiting oxygen concentration are described.

This information can be very helpful to first responders, emergency personnel, risk managers and regulatory agencies in developing tactics and strategies to control and prevent explosion hazards from the storage and use of battery packs. Measurements of this type can also be used to provide design guidance for containment enclosures and explosion venting or blow off panel design that can mitigate the hazard of combustible gases vented during failures in lithium ion cells and large battery packs.