| Work Detail |
LG Chem has announced that its platform technology R&D team has developed a temperature-sensitive safety reinforced layer (SRL), a material described as capable of suppressing thermal runaway. The material was analyzed in collaboration with researchers at Pohang University of Science and Technology (POSTECH) in South Korea, while safety verification was conducted in partnership with LG Energy Solution.
Thermal runaway has plagued the lithium-ion battery industry since its inception. While measures to mitigate safety risks have advanced along the way, reaching a very high point today, “thermal events” – which generate gas and can lead to full combustion – have not been definitively eradicated.
Now, South Koreas LG Chem claims to have found a solution to this age-old problem. The conglomerate announced Tuesday that its Platform Technology R&D team has developed a temperature-sensitive security reinforced layer (SRL), a material it describes as capable of suppressing thermal runaway.
SRL is a composite material that changes its electrical resistance depending on temperature and acts as a “fuse” that blocks the flow of electricity in the early stages of overheating.
The material comes in the form of a thin layer just 1 micrometer (1µm) thick – about one-hundredth the thickness of a human hair – sandwiched between the cathode layer and the current collector (an aluminum foil that acts as an electron path). According to LG Chem, when the battery temperature exceeds the normal range of 90°C to 130°C, the material reacts to the heat, altering its molecular structure and effectively suppressing current flow.
The material is described as highly temperature-sensitive, with its electrical resistance increasing by 5,000 ohms (O) for every 1°C increase in temperature. The materials maximum resistance is more than 1,000 times that at normal temperatures, and it also exhibits reversibility, meaning the resistance decreases and returns to its original state, allowing current to flow normally again once the temperature is lowered.
Test results
LG Chem’s Platform Technology R&D team worked in collaboration with Professor Lee Minah’s team from POSTECH’s Battery Engineering Department to analyze the material. Safety verification was conducted in collaboration with LG Energy Solution, the conglomerate’s battery storage division. The research results were published online in the September issue of Nature Communications .
In its statement, LG Chem said that in both impact and penetration tests, 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 from occurring.
In a nail penetration test with mobile lithium cobalt oxide (LCO) batteries, only 16% of the normal batteries did not catch fire. However, none of the batteries with the thermal runaway suppressor material experienced any fire incidents.
In an impact test using nickel cobalt manganese (NCM) batteries for electric vehicles, in which a 10-kilogram weight was dropped on the batteries, all of the normal batteries caught fire. In contrast, 70% of the batteries equipped with the thermal runaway suppressor material did not catch fire at all, while the remaining 30% did catch fire but were extinguished within seconds.
"Impact tests performed with 3.4 Ah batteries show that the SRL reduces battery explosions from 63% to 10%," the researchers write in their paper.
According to LG Chem, previous methods of placing temperature-sensitive materials inside the battery cell often posed problems of slow reaction times or reduced energy density. Instead, the newly developed material overcomes these shortcomings and enables rapid application in mass production processes.
“This is a tangible achievement of research that can be applied to mass production in a short time. We will improve safety technology to ensure that customers can use electric vehicles with confidence and help strengthen our competitiveness in the battery market,” said Lee Jong-Ku, Chief Technology Officer of LG Chem.
In their research paper, the authors write that they have demonstrated roll-to-roll production of SLR on current collectors at a rate of 5 km per day.
LG Chem has completed safety verification testing of thermal runaway suppression material in mobile phone batteries and plans to continue safety testing of large-capacity batteries for electric vehicles through next year. |
