▶ SNU research
Jongwoo Lim, Professor at the Department of Chemistry
If an electric vehicle (EV) catches fire, the “thermal runaway” phenomenon occurs, in which the battery temperature soars to 1,000°C or higher in several seconds. The safety issue of EVs is one of the key issues that must be resolved prior to the full-scale era of EVs.
Last August, Professor Lim's team from the Department of Chemistry at Seoul National University discovered the “self-amplifying loop,” a reaction mechanism for thermal runaway in which
temperatures soar drastically. They succeeded in revealing that the self-amplifying loop exchange reaction between the cathode and anode during thermal runaway is the core structure and
that the thermal runaway reaction worsens more rapidly than previously anticipated. The results of this study were published as featured on the cover of Advanced Materials, a
renowned international academic journal.
“This research evolved naturally from discussions on a specific issue with doctors at Samsung SDI approximately five years ago. Due to the significance of the thermal runaway phenomenon in
automobile batteries, Seoul National University received research requests. We are continuously conducting follow-up research in this pipeline.”
There have been many suspicions about battery cell manufacturers as the cause of battery fires.
“My team has taken a new approach to the principle of finding the causes of thermal runaway. Oxygen comes out of the cathode and anode of a battery, where the electrolyte is a flammable,
liquid organic substance. Previously, a fire was considered to occur when the oxygen of the flammable gas came out and reacted. The Seoul National University research team assumed that the
flammable gas comes out first at low temperatures from the anode. In this phenomenon, the cathode stimulates the oxygen to emerge quickly, which in turn adds stimulation to the anode,
enabling the flammable gas to emerge rapidly. This team discovered for the first time that the exchange reaction of continuously stimulating each other appeared.”
Similar to the release of carbon dioxide from a burning candle, the release of flammable gases and oxygen from the cathode triggers an oxidation reaction. In this scenario, individuals
mistakenly believe that the gas remaining in the extinguished fire is carbon dioxide. However, the remaining carbon dioxide ignites another reaction.
“This research team discovered that the carbon dioxide remaining after the fire extinction further stimulates the lithium in the anode. The additional stimulation causes a tremendous
exothermic reaction, and the principle that thermal runaway is further stimulated has been discovered. As researchers, we cannot do anything about the emission of carbon dioxide. However,
we have coated the anode to prevent carbon dioxide from stimulating the anode and causing an exothermic reaction.”
Conventionally, people occasionally coated the battery cathode to prevent the release of oxygen. This is a well-known fact in the industry. Through this study, the research team discovered
a new concept: coating the anode can prevent the anode stimulation of carbon dioxide. The research team tested its application and confirmed that it is applicable in a realistic
environment.
Coating the battery anode with aluminum oxide can reduce the possibility of thermal runaway. Professor Lim said, “We have only confirmed that the applicability of the principle that the
research team has identified through the thermal runaway analysis method, while its commercialization requires more time.”
“The problems of the EV battery will not arise from the beginning. Just as the eating habits of humans affect health, the same pattern applies to EV batteries. There may be potential risk
factors inside the EV depending on how the car is driven and how the battery is manufactured.”
South Korea, China, and Japan are the leaders in battery manufacturing. What does he think about South Korea's potential for growth? “I have been to China four times this year. What I felt
from the industry sites is that the world wants South Korea and Japan to check China’s dominance. Five or ten years ago, South Korea and Japan were ahead of China. However, China has grown
rapidly over recent years. This change has occurred after the Chinese government decided to bet everything on the EV battery industry.”
In terms of global technology levels, domestic battery technology is outstanding. South Korea can be seen as a leader in the industry. However, the market is concerned about China's
potential to attack it with low unit prices. If China's technology advances in the future, that country could exploit an advantage in its industrial competitiveness. Given that South Korea
currently has excellent technology, there is a need for continuous investment in research on automobile batteries.
We hope that the outcome of this study will serve as a driving force to heighten the competitiveness of South Korean companies that seek high-nickel cathodes as their major product.
