[Fire-Prone Battery]② Busy Developing Technologies to Stop 'Thermal Runaway'

High-Capacity Batteries Essential to Extend Driving Range
Dedicated to Developing Technology to Reduce Fire Risk

[Asia Economy Reporter Oh Hyung-gil] The Ioniq 6 has been certified as the electric vehicle with the longest driving range on a single full charge in the United States (581 km). Surpassing Tesla's Model 3 (576 km), it is expected to be a hit ahead of its release in the first half of the year. The battery capacity of the Ioniq 6 is 77.4 kWh. Based on the average monthly electricity consumption of a family of four, which is 307 kWh, the Ioniq 6 battery can supply electricity for household use for about a week.

To increase the driving range of electric vehicles, a high-capacity battery is essential. A larger battery capacity means more stored energy inside. In the event of a fire, it inevitably leads to a major accident.

Battery manufacturers explain that with the current level of technology, batteries with large-scale energy inherently carry the risk of fire. This is why they are dedicated to developing technologies to prevent battery fires.

Causes of electric vehicle battery fires include external impact, overcharging, and manufacturing defects. When a strong external impact occurs due to an accident, the separator that separates the positive and negative electrodes of the battery cell can be damaged, causing a short circuit between the electrodes, which can generate heat and sparks, leading to a fire.

The "thermal runaway phenomenon" is critical in electric vehicle fires.

This refers to the situation where the internal temperature of the battery pack rapidly rises above 800 degrees Celsius as it is damaged, causing the fire to spread. Because the internal temperature is so high, it is very difficult to extinguish a battery fire. Sometimes, even after putting out the fire, it reignites. When the battery is charged beyond its specified capacity, the temperature of the electrolyte inside the battery rises, melting the separator and causing a fire.

Accordingly, battery manufacturers are researching battery cell and pack technologies that enhance safety. The key is to prevent fires at the cell level and to design packs that can suppress fire spread.

SK On uses a Z-folding method that wraps the material in a zigzag pattern between the positive and negative electrodes without cutting the cell separator into individual sheets. Even if slight distortions occur during the stacking of hundreds of positive and negative electrodes, the separator easily blocks contact between the positive and negative electrodes. They are also researching pack technologies that prevent fire from spreading to surrounding cells even if a fire occurs in a single battery cell.

Samsung SDI has filed a patent for a battery pack with improved heat dissipation performance. This method installs heat pipes of different heights between battery cells, enabling heat dissipation through both cooling air and heat pipes, thereby enhancing thermal insulation performance.

LG Chem has developed a flame-retardant engineering plastic material that prevents deformation caused by heat. With excellent heat resistance, when applied to electric vehicle battery pack covers, it can block heat for a longer time compared to general flame-retardant plastics. Internal tests showed it prevented flame propagation caused by thermal runaway for over 400 seconds even at 1000 degrees Celsius.

Last month, the government formed a public-private joint task force (TF) with battery manufacturers to respond to electric vehicle fires. They plan to discuss emergency escape devices such as vehicle door opening in case of collisions or other emergencies, and measures to reduce the possibility of fires.