According to Kim, workers who fled the fire said the fire started when a single battery cell caught fire, triggering a series of explosions among some of the 35,000 lithium battery cells stored on the second floor of the factory.
Lithium batteries can cause fires when the internal layers are compressed, causing a short circuit. The layers can be compressed by a sudden impact, such as during a vehicle collision, or by the gradual swelling of the batteries due to regular use.
Lithium is a metal that can store large amounts of energy in a small space, which is why it is attractive as a battery material. But that also means there is a lot of energy available that can be converted into heat and even fire in the event of a short circuit. Lithium battery fires have become a growing problem in the United States and elsewhere, and are an industry-wide concern for battery manufacturers.
Aricell, which owns the Hwaseong plant, makes batteries that are often used to power electricity and other utility networks.
On Monday, intense flames, toxic smoke and the risk of further explosions hampered firefighters’ efforts to search for the missing workers. Television footage of the fire showed large flames and thick clouds of smoke billowing from the factory. Footage taken after the fire was put out showed the building burned, with the roof collapsed.
