Fire Characteristics of Lithium-ion Battery According to the State of Charge in an Accelerating Rate Calorimeter

Abstract

Recently, the interest in ecofriendly energy as an alternative to fossil fuels, which cause climate change and sea level rise, has increased. To achieve the efficient utilization of ecofriendly energy, such as a renewable energy, considerable effort has been made to use energy storage systems (ESSs) and smart grid systems. However, many safety problems, such as battery fires caused by the increase in the use of secondary batteries, significantly limit their application scope. In this study, to investigate the fire characteristics of lithium ion batteries (LIBs), the characteristics of the spontaneous exothermic reaction and thermal runaway phenomenon that occur at each temperature of an LIB battery were investigated using an accelerating rate calorimeter. The batteries used in the experiments were standard 18650 cylindrical batteries with a capacity of 2600 mAh, and they were tested at three different state-of-charge (SOC) levels: 0%, 50%, and 100%. The type of heat generated by each experimental condition was classified into four stages, and the existence and temperature rise characteristics of each stage were investigated according to the SOC. Although thermal runaway occurred at both 50% and 100% SOC, the reaction at 50% SOC did not escalate into violent explosions like the reaction observed at 100% charging. Furthermore, the activation energies for the thermal runaway observed in the experiments conducted at 50% and 100% SOC are presented.