The hazards posed by thermal runaway in lithium-ion batteries have been tackled by researchers in South Korea: a new temperature-responsive material is reportedly capable of suppressing battery overheating and flammability.

The composite material, derived from polythiophene and carbon additives, interrupts current flow during voltage changes its electrical resistance based on temperature and functions as a fuse to block the flow of electricity in the early stages of overheating. A layer just 1 μm thick is placed between the cathode layer and the current collector. A temperature rise in the 90° C to 130° C range causes the material to react, altering its molecular structure and effectively suppressing the flow of current.

As reported in Nature Communications, the electrical resistance of this layer increases by 5,000 ohms for every 1° C increase, signaling its responsiveness to temperature. As the temperature returns to a preferred realm, the resistance declines to permit resumption of current flow.

Battery impact and penetration tests demonstrated that those 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.

Only 16% of lithium cobalt oxide batteries lacking the new material did not catch fire during nail penetration tests, while none of the units equipped with the thermal runaway suppression material experienced any fire incidents.

Researchers from Pohang University of Science and Technology, LG Chem and LG Energy Solution also successfully demonstrated the roll-to-roll production of the material on current collectors at a rate of 5 km per day.