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.
Fires can occur in lithium batteries 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 from 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 this also means that there is a lot of energy available that can turn into heat and even flame in the event of a short circuit. Lithium battery fires have become a growing problem in the United States and elsewhere and represent an industry-wide concern for battery manufacturers.
Aricell, which owns the Hwaseong plant, produces batteries often used to power electricity grids and other utilities.
Heavy flames, toxic smoke and the risk of further explosions hampered firefighters’ efforts to search for missing workers on Monday. Television footage of the blaze showed large flames and thick clouds of smoke billowing from the factory. Footage taken after the fire was extinguished showed the building burned out, with its roof collapsed.