[Insight & Opinion] The Unthinkable Electric Vehicle Fire in an Underground Parking Lot

Limitations in Fire Suppression Due to Battery Structure
Damage to Lithium-Ion Separators as the Cause
Need for Enhanced Separator Technology and Fire Safety Measures

A Mercedes-Benz electric vehicle that had been parked for three days in an underground parking lot of an apartment complex in Incheon suddenly emitted smoke and exploded. The fire, which lasted for 8 hours and 20 minutes from early morning, resulted in 23 residents being transported to hospitals, and about 70 vehicles were damaged. The electrical and piping facilities in the underground parking lot were severely damaged, and approximately 480 households across five apartment buildings were devastated. Structural damage to the apartment complex is also a concern. Fortunately, there were no serious casualties.

It is common knowledge that electric vehicle fires in underground parking lots are extremely dangerous. This is due to the nature of electric vehicle fires, which emit a massive amount of deadly toxic gases and spread rapidly. Because of the completely sealed structure of the battery, there is no effective fire suppression method other than artificial water tanks. Ultimately, electric vehicle fires occurring in underground parking lots with low entrances and high vehicle density in apartments are disasters that no one can easily handle.

Electric vehicle fires in underground parking lots have occurred before. There were 10 cases last year alone. The risk posed by electric vehicles in underground parking lots cannot be ignored. Moreover, the ‘eco-friendliness’ of electric vehicles cannot be used as an excuse to overlook such risks. The goal of overcoming the climate crisis does not protect against the dangers of electric vehicles. Fortunately, from this year, new regulations have been introduced to restrict the installation of chargers below the fourth basement level. However, safety measures for parking lots above the third basement level have not yet been established.

Lithium-ion batteries, widely used in mobile phones, laptops, kickboards, electric vehicles, and energy storage systems (ESS), are revolutionary new technology that emerged in the 21st century. They utilize lithium, the lightest metal in the world, in a chemically stabilized ‘ion’ form. As the use of lithium-ion batteries has increased, lithium, the 25th most abundant element on Earth, has come to be regarded as ‘white petroleum’ or ‘white gold.’

However, problems do exist. Issues arise when the ‘separator,’ which selectively allows only lithium ions to pass through, is damaged due to physical impact, structural defects in the battery, or overcharging. When an internal short circuit causes excessive current flow, a large amount of heat is generated. The electrolyte inside the sealed battery, in liquid or gel form, evaporates, causing the battery to explode and release toxic gases. Fires originating from ‘battery packs’ composed of many batteries can lead to ‘thermal runaway.’ The sturdy sealed structure designed to withstand electrolyte leakage and impact makes fire suppression even more difficult.

Lithium-ion battery fires mainly occur in electric vehicles, kickboards, and ESS. While the quality of mid- to low-priced batteries is an issue, neglect in battery management may be a more serious cause. This is especially true for ESS units left unattended in small-scale solar and wind power installations. It is also important to remember that 72 electric vehicle fires occurred last year. There were also 115 electric kickboard fires in 2022.

Abandoning lithium-ion batteries is not the solution. More active development of technologies to strengthen the separators of lithium-ion batteries is necessary, as well as regulations to ensure more thorough management of lithium-ion batteries. Efforts are also needed to accept the inconvenience of restricting electric vehicle access to underground parking lots and to relocate chargers without thorough fire safety measures to above ground.

Lee Deok-hwan, Professor Emeritus at Sogang University, Chemistry and Science Communication