The widespread and increasing adoption of lithium-ion batteries for multiple applications has accelerated the demand for batteries. Updated transportation safety guidelines must be followed in order to avoid hazards during the shipment of batteries from manufacturing sites to end-consumers. Despite existing guidelines in place, there have been instances of battery-related safety hazards during transportation. Different off-nominal conditions arising due to mechanical, electrical, or environmental conditions can lead lithium-ion cells into failure and cause thermal runaway in worst-case scenarios. Outcomes including smoke, high temperatures, fire, and explosion are possible following a thermal runaway event. Hazards are magnified when thermal runaway in a single cell is propagated to other cells within a package or battery causing a chain of highly exothermic reactions.

In this study, effectiveness of several barrier materials was tested to mitigate the propagation of thermal runaway occurring in a single cell within the package. 25-cells configurations of lithium-ion cells were placed within shipping boxes and a single cell at the center of the configuration was triggered using an external heating method to go into thermal runaway. Among different test variations, regular cardboard and UN-rated shipping boxes were tested. Test articles were arranged in 25 single cell configurations (not connected) representing shipment of loose cells and 25P electrically connected configurations representing shipment of batteries. Barrier materials with 2 mm to 4mm intercell separation and different physical properties were tested. The materials tested were either in sheet form or a mold-pattern. State-of-charge (SOC) of all the cells in the container were either at 33% SOC or 100% SOC to represent current shipping SOC regulations and to study the worst-case hazard conditions.

Thermally insulating, conducting, and phase changing materials along with their effectiveness in mitigating the propagation of thermal runaway will be discussed. Additional thermal management requirements in batteries due to the conduction through tabs will also be highlighted through the results. Requirements for flame and fire retardation for preventing rapid propagation of thermal runaway will be presented. Efficacy of materials from different manufacturers at preventing the propagation of thermal runaway will be summarized.