A fire at a battery manufacturing plant in South Korea that killed 23 people on Monday, June 24, highlights the growing need for more education and regulation when it comes to battery production, storage, use, and disposal. It also offers an opportunity to discuss the differences between lithium metal batteries and lithium-ion batteries and the unique fire safety hazards they present.

Lithium metal vs lithium-ion batteries 

Although some news sources have used the terms “lithium batteries” and “lithium-ion batteries” interchangeably in reporting on the recent South Korea blaze, it’s important to note that there are different kinds of lithium-based batteries, and a lithium metal battery is not the same thing as a lithium-ion battery. According to its website, Aricell, the South Korean company that operated the plant where Monday’s deadly fire occurred, specializes in “lithium thionyl chloride battery production.” Lithium thionyl chloride batteries are a type of lithium metal battery, suggesting the fire involved lithium metal batteries, not lithium-ion batteries.

All batteries are made up of two electrodes (an anode and a cathode) and an electrolyte. The anode is the negative electrode, which releases electrons, and the cathode is the positive electrode, which receives electrons. The electrolyte is the material between the two electrodes through which electrons flow. The flow of electrons is what creates electricity.

In lithium metal batteries, metallic lithium serves as the anode. In lithium-ion batteries, however, no metallic lithium is present. It can be confusing because the chemical reactions that occur inside both lithium metal and lithium-ion batteries involve positively charged ions of lithium.

In a practical sense, the key difference between a primary lithium metal battery and a secondary lithium-ion battery is its ability to be recharged. Lithium-ion batteries can be recharged and are currently the most common battery used in the everyday devices you can recharge, like your cellphone or your laptop.

Most lithium metal batteries, on the other hand, cannot be recharged. Similar to the alkaline batteries you would find in a TV remote but much longer-lasting, lithium metal batteries have an expected lifespan. They might be used in devices such as pacemakers or wristwatches.

Fire hazards of lithium-based batteries

Both lithium metal batteries and lithium-ion batteries present unique fire safety challenges.

In lithium-ion batteries, a chemical reaction known as thermal runaway can occur. During thermal runaway, battery cells begin uncontrollably heating up, and this reaction can spread from battery cell to battery cell and lead to a fire or explosion. Since lithium-ion batteries can be recharged, improper charging practices and the use of low-quality charging equipment introduces the risk for thermal runaway to occur.

Many examples of thermal runaway leading to fires involving lithium-ion batteries have been observed in recent years. Fires involving the lithium-ion batteries used to power electric vehicles have challenged fire services around the world, generally requiring more time and more water to extinguish than fires involving internal combustion engines. In New York City alone, hundreds of fires involving lithium-ion battery–powered electric bikes and electric scooters, commonly called e-bikes and e-scooters, have occurred, prompting officials to urgently seek solutions.

RELATED: Learn more about lithium-ion battery safety from NFPA

The hazards that are present in a lithium metal battery fire include the generation of toxic gases, the presence of combustible metals, and the potential for an explosion. While the presence of toxic and flammable gas is common to both lithium metal and lithium-ion battery fires, the involvement of combustible metals can make fires involving lithium metal batteries difficult to extinguish. Depending on the quantity of flammable metal, the fire could require substantial amounts of Class D fire suppressants.

The hazards of lithium thionyl chloride batteries, specifically, have been well documented over the years. Both metallic lithium and thionyl chloride are highly reactive with water. “Safety hazards have ranged from mild venting of toxic materials to violent explosions and fires,” a NASA report published on lithium thionyl chloride batteries in 1986 reads.

It remains unclear what exactly started the fire at the Aricell factory in South Korea, although video released in the days following the incident shows containers filled with what appear to be batteries begin suddenly spewing white smoke before bursting into intense flames. Fires in industrial or manufacturing properties are a common occurrence regardless of the goods being made. Between 2017 and 2021, fire departments in the United States responded to an annual average of 36,784 fires at industrial or manufacturing properties, according to data from NFPA. That’s more than 100 such fires every day.

 Video posted to YouTube by the New York Post shows the moment batteries caught fire at a lithium metal battery manufacturing plant in South Korea June 24.

The victims in Monday’s factory blaze included 18 migrants from China and one from Laos, as well as two South Koreans, according to The New York Times. “They were found dead on the 12,500-square-foot second floor of the factory,” the Times reported. “The floor had two unlocked exit staircases leading outside, but the workers appeared to have been overcome by the flames and toxic smoke before reaching them.”

A new code on the horizon

Currently, codes and standards from various standards development organizations address certain aspects of battery safety.

Released in 2019, NFPA 855, Standard for the Installation of Stationary Energy Storage Systems, applies to batteries when they are used in energy storage systems (ESS). Since 2016, UL has published UL 2272, a standard for the certification of electrical systems found in personal electric micromobility devices, and in 2020, UL published a standard specific to e-bikes, UL 2849. But there is no single, comprehensive standard that provides a full spectrum of battery safety requirements.

That could change in the near future. Last month, NFPA announced that it was considering the development of NFPA 800, Battery Safety Code, to provide uniform minimum requirements to address the fire, electrical, and life safety hazards created by batteries in all forms and through the entire lifecycle of a battery, from production to disposal.

“It is the intent to reference existing related standards by NFPA and other standards developing organizations, where applicable, and focus on developing requirements where there are gaps,” a press release about NFPA 800 reads. “Requirements are anticipated to include fire, explosion, and other dangerous conditions related to battery technologies as experienced through the lifecycle of a battery: raw materials and battery production through storage, use, and end of life.”

Learn more about NFPA 800 and how to get involved.