Are Sprinklers Useless? ... How Do Battery Factories Prevent Fires?

Lithium Primary Batteries More Vulnerable Than Secondary Batteries
Lithium Metal Reacts with Water to Produce Hydrogen Gas
Fire-Experienced Bitsrocell Distributes Factories
Secondary Battery Companies Also Prepare Fire Countermeasures

The lithium battery factory fire site in Seosin-myeon, Hwaseong-si, Gyeonggi-do, ahead of the on-site inspection on the morning of the 25th. [Image source=Yonhap News]

It has been revealed that the Hwaseong Aricell factory in Gyeonggi, where more than 20 people died in a large fire, did not have sprinklers installed. Lithium battery factories are known to often find sprinklers ineffective due to lithium’s property of reacting violently with water, but there are opinions that they are necessary to prevent thermal runaway. There is also an urgent need to distribute Class D fire extinguishers specialized for metal fires such as lithium.

According to statements from Aricell officials on the 25th, it is understood that the battery factory where the fire occurred either did not have sprinklers installed or they were not operational. Aricell is a subsidiary of Esconic and produces lithium primary batteries. Lithium primary batteries are non-rechargeable batteries and differ completely in composition and use from lithium-ion secondary batteries used in electric vehicles.

Aricell produced lithium thionyl chloride primary batteries (Li/SOCL2). These batteries use lithium metal for the anode, carbon for the cathode, and thionyl chloride as the electrolyte. Lithium thionyl chloride primary batteries have high operating voltage and energy density, and a long lifespan of about 10 years, making them useful for powering communication equipment, safety facility monitoring, oil exploration, and military equipment.

Alkali metals such as lithium, sodium, and potassium react rapidly when in contact with water, generating hydrogen gas and making explosions likely. For this reason, it appears that sprinklers were not installed in this factory.

Lithium primary batteries are more vulnerable to fire than lithium secondary batteries. Lithium-ion secondary batteries contain lithium in an oxidized form, whereas lithium primary batteries contain pure lithium metal. Unlike secondary batteries, which are shipped in a partially discharged state, primary batteries are stored and shipped fully charged. Because they contain high energy, even slight external impact can lead to fire.

In the event of an electric vehicle fire, methods such as fully submerging in water or using a cover to block oxygen for smothering extinguishment are applied. Battery packs are also designed to prevent thermal runaway and heat transfer.

Domestic battery factories are preparing for fires in a similar manner.

An LG Energy Solution official explained, "Individual battery cells are stored in separate trays with spacing to prevent contact," adding, "In addition to ceiling sprinklers, individual sprinklers are installed inside each tray for rapid response." LG Energy Solution operates its own fire prevention centers at production and research facilities such as the Ochang Energy Plant to enable primary response in emergencies.

A Samsung SDI official also said, "We have small water tanks and carbon dioxide fire extinguishers available for emergency use inside the factory," and added, "Sprinklers are necessary to prevent heat from spreading and to stop thermal runaway from transferring."

Previously, in April 2017, when the Yesan factory was completely destroyed by fire, Bitsrocell, a leading domestic primary battery company, paid special attention to fire prevention when building a new factory in Dangjin. A Bitsrocell official stated, "In addition to sprinklers, we have Class D fire extinguishers specialized for metal fires such as lithium." However, Class D fire extinguisher installation is not yet mandatory in Korea.

Additionally, Bitsrocell separated the production process, increasing the factory buildings from the original three to 21, each designed with reinforced concrete structures. The trays used to transport batteries are made of flame-retardant materials. Kang Kyung-sung, First Vice Minister of the Ministry of Trade, Industry and Energy, plans to visit Bitsrocell on the day to inspect fire prevention measures.