Fire behavior of lithium-ion battery with different states of charge induced by high incident heat fluxes

Numerous accidents including fires and explosions occurring in transportation and storage of batteries enhance the need of studying the fire performances on batteries. In the current work, series bench-scale tests are conducted using a cone calorimeter to explore the fire behavior of lithium-ion battery. The influence of two key factors, namely state of charge (SOC) and incident external heat flux, on the battery fire characteristics is especially investigated. Combustion behavior, time to ignition (TTI), heat release rate (HRR) and fire risk assessment are obtained. The battery with higher SOC under high incident heat flux presents a fierce combustion process and higher surface temperature than the others. It is noteworthy that the time to ignition and time to peak HRR (TTP) decrease with the SOC, whereas the peak HRR (pHRR) and total heat release (THR) increase overall. On the whole, the increment of incident heat flux causes the decrease in TTI and TTP, while the pHRR and THR increase at higher incident heat flux. And the values of TTI agree well with the classical ignition model. Finally, the fire risk of battery with different SOCs under various incident heat fluxes is also highlighted.