"Can't Turn It Off"... Lithium-Ion Battery Fire Risk Back on the Table

Fire at SK C&C Data Center Blamed for Kakao Outage
"Chronic Issue"... Use of Volatile Electrolyte Substances Poses Ignition Risk with Rapid Temperature Rise
Active Research on Next-Gen Technologies Like All-Solid-State Batteries... Early Commercialization Uncertain

[Image source=Yonhap News]

[Asia Economy Reporter Kim Bong-su] The cause of the fire at the SK C&C Internet Data Center (IDC) in Pangyo, Gyeonggi Province, has been identified as the spontaneous ignition of lithium-ion batteries used in the uninterruptible power supply (UPS) attached to the servers, raising concerns about the 'battery risk.' This issue has drawn attention before, especially during electric vehicle fires where water is sprayed for hours and fire-retardant blankets are applied, yet the fire intensifies uncontrollably once the blanket is removed. In the case of the SK C&C fire, although the initial fire suppression system was activated, it failed to extinguish the fire, bringing the safety of lithium-ion batteries back into the spotlight.

Vulnerable to Fire and Explosion from the Start

Lithium-ion batteries generate electricity through chemical reactions involving lithium. They consist of a cathode made of lithium oxide, an anode made of graphite, an electrolyte that serves as the ion transport medium, and a separator made of synthetic resins such as polyethylene (PE) or polypropylene (PP). Since their development in 1976, they have been widely used in almost all secondary battery markets, including mobile phones, laptops, and electric vehicles, due to their light weight, compact size, high efficiency, and ability to be reused hundreds of times.

The problem lies in their vulnerability to fire and explosion. This is because the electrolyte, which serves as the ion transport path, contains volatile solvents that are highly flammable. If a short circuit occurs inside the battery, causing a sudden temperature rise, it can lead to ignition, fire, or even explosion. This risk is especially high in large-capacity UPS or energy storage systems (ESS). External shocks that cause electrolyte leakage also increase the risk of ignition. These issues have been raised repeatedly whenever fires occur in electric vehicles or ESS devices.

Structure of a lithium-ion battery. Image source=Samsung SDI

Even Blocking Oxygen, 1000℃ Heat Emission Causes Reignition

Lithium-ion batteries used in UPS or ESS consist of thousands of battery cells about the size of a fingertip. If even one cell’s separator is damaged and the temperature rises sharply, adjacent cells also heat up. Eventually, thousands of battery cells each emit heat exceeding 1000℃, spreading the fire. This phenomenon is known as 'thermal runaway.' Once thermal runaway begins, extinguishing the fire becomes difficult, unlike ordinary fires.

It is impossible to extinguish such fires with a standard powder extinguisher. The only method is to continuously spray water for hours and block oxygen, but even this is challenging. Even when covered with a fire-retardant blanket to block oxygen, lithium-ion batteries continue to emit intense heat. Removing the blanket causes the fire to reignite. Because extinguishing the fire once it starts is so difficult, preventing fires from occurring in the first place is more important. Therefore, places that install UPS or ESS, including IDCs, should keep a separate floor empty to store lithium-ion batteries and avoid overcharging. Additionally, effectively dissipating the heat generated during charging and use is crucial.

Um Seung-wook, Director of the Next-Generation Battery Research Center at the Korea Electrotechnology Research Institute, explained, "Heat generation in lithium-ion batteries can occur due to electron collisions or physical short circuits, or when excessive capacity is charged," adding, "The higher the capacity, the more difficult it is to dissipate the generated heat."

This is Why Next-Generation Battery Research is Underway

Due to the risks associated with lithium-ion batteries, next-generation battery research is being conducted worldwide. Solid-state batteries, which replace liquid electrolytes with solid ones, are a representative example. Using solid electrolytes instead of liquid ones greatly enhances safety. Samsung SDI developed a solid-state battery technology in March 2020 that enables an 800 km driving range on a single charge and can be used over 1000 times, publishing their findings in the international journal 'Nature Energy.' Moreover, global competition is fierce, with companies like Toyota in Japan and LG Energy Solution also developing similar technologies.

Battery manufacturers are confident about commercializing solid-state batteries within a few years. However, the scientific community points out that there is still a long way to go. The manufacturing cost is about twice that of lithium-ion batteries due to the solid materials used as electrolytes, and high internal resistance (interfacial resistance) between solid particles results in lower efficiency and instantaneous output. Director Um stated, "Currently, many materials are being developed at the laboratory level, and research is ongoing to improve performance and economic feasibility," adding, "It is difficult to predict when competitively priced solid-state batteries will be developed and commercialized."

This content was produced with the assistance of AI translation services.