Abstract:

The influence mechanism of different states of charge (SOC) on the thermal runaway hazard of batteries was revealed to improve the thermal safety of batteries and reduce the thermal disasters of new energy vehicles. The thermal runaway characteristics of 21700 lithium batteries were investigated under several SOC ranging from 100% to 0%, including the surface temperature, operating voltage, mass loss, energy, TNT equivalent, and damage radius of the batteries during thermal runaway. The results show that the temperature rise of the battery rises with the increase of SOC, and the time needed to trigger the thermal runaway of high power battery is shorter, 100% SOC battery triggers the thermal runaway in 603 s, which is 59.1% shorter than 25% SOC, and the risk factor is greater; the larger the SOC, the larger the mass loss of the battery after the thermal runaway; the energy released during the process of the thermal runaway, the TNT equivalent and the radius of destruction all increase with the increase of SOC, and there is a positive correlation between the thermal runaway hazard of the battery and SOC.

Key words: lithium battery, state of charge(SOC), thermal runaway, radius of destruction