Effect of State of Charge on Thermal Runaway Characteristics of 18650 Lithium Ion Batteries

In order to further investigate the thermal runaway characteristics of 18650 lithium ion batteries and the related hazard, experiments of 18650 lithium ion batteries with different SOC (State of Charge), such as 50%SOC and 20%SOC under two initial pressures of 96kPa and 61kPa are conducted. The results show that the chemical reaction of 20%SOC batteries is weaker than that of 50%SOC batteries, leading to a lower peak temperature, less CO and CO2release, and less mass loss. Under 61kPa, the initial combustion time is longer, the reaction intensity is weaker, more CO and CO2release and less mass loss than that under 96kPa. The fire hazard of 50%SOC batteries is larger than that of 20%SOC batteries.