> The material comes in the form of a thin layer, just 1 micrometer (1μm) thick – about one hundredth the thickness of human hair – positioned between the cathode layer and the current collector (an aluminum foil that acts as the electron pathway). When the battery’s temperature rises beyond the normal range, between 90°C and 130°C, the material reacts to the heat, altering its molecular structure and effectively suppressing the flow of current, LG Chem said.

> The material is decribed as highly responsive to temperature, with its electrical resistance increasing by 5,000 ohms (Ω) for every 1°C rise in temperature. 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.

To the best of my searching, a typical lithium ion battery has roughly 20-30 cathode-and-current-conductor layers. So naively this would add less than 50 microns to the battery thickness.

Also, the open-access article is here: https://www.nature.com/articles/s41467-024-52766-9