LG Chem says it has developed a material capable of suppressing the dangerous process of thermal runway in malfunctioning lithium-ion batteries.
The Korean conglomerate’s platform technology R&D team says the safety reinforced layer (SRL) material has been analyzed by researchers at Pohang University of Science and Technology (POSTECH) in South Korea, with safety verification carried out by LG Energy Solution.
Details of the material and the company’s research have been published in the September edition of the Nature scientific journal.
Lee Jong-gu, CTO of LG Chem, said: “This is a tangible research achievement that can be applied to mass production in a short period of time. We will enhance safety technology to ensure customers can use electric vehicles with confidence and contribute to strengthening our competitiveness in the battery market.”
Lithium-ion batteries are used in a wide range of technologies, including mobile phones, electric vehicles, and for backup energy storage in data centers
When damaged, the batteries can go into thermal runway. The process occurs when the cathode and nanode come into direct contact, causing a reaction that can lead to overheating and highly combustible vapor being released by the cell. This leads to a risk of fire or explosion, and thermal runway is one of the biggest causes of electric vehicle fires. Several data center fires are thought to have been caused by lithium fires.
To put a stop to this, the LG Chem team has developed the SRL, which is made of a composite material that changes its resistance as temperature increases. Because of this, it can act as a “fuse,” blocking the flow of electricity as overheating starts.
The SRL comes in the form of a thin layer, just 1 micrometer thick - about 1/100th the thickness of a human hair - which is positioned between the cathode layer and the current collector in the battery. When the battery’s temperature rises beyond the normal range, between 90°C-130°C (194-266°F), the material reacts to the heat, altering its molecular structure and effectively suppressing the flow of current.
The material’s maximum resistance is over 1,000 times higher than at normal temperatures, and it also features reversibility, meaning the resistance decreases and returns to its original state, allowing the current to flow normally again once the temperature drops.
Researchers carried out battery impact and penetration tests and found that batteries equipped with the thermal runaway suppression material either did not catch fire at all or extinguished the flames shortly after they appeared, preventing a full-blown thermal runaway event.
LG Chem said it has completed safety verification tests for the thermal runaway suppression material in mobile batteries and plans to continue safety testing for large-capacity electric vehicle batteries through next year.