A new exploration of the fire behaviors of large format lithium ion battery

In this paper, the fire behaviors of 60 Ah LiFePO4/graphite batteries with no safety valve are evaluated using an in situ calorimeter. The batteries experience a stable combustion stage with a small-scale flame rather than immediate jet fire after ignition and the special combustion process is analyzed and discussed in detail. It takes 201 s from ignition to thermal runaway for fully charged battery under an incident heat flux of 11.1 kW m(-2). Such a time interval is beneficial for a possible early warning of the battery thermal runaway. Several characteristic parameters, including the ignition time, surface temperature, mass loss, heat release rate (HRR), and flame size are systematically determined. The peak HRR can be as high as 82.3 kW and the maximum average flame height for batteries under an incident heat flux of 11.1 kW m(-2) reaches 634.6 mm. The influence of different state of charge (SOC) and incident heat flux are also investigated. The results show that the fully charged batteries exposed to high external heat flux are more vulnerable to have thermal runaway.