Energy-dense batteries, such as the lithium-ion versions that are widely used in electronics and electric vehicles, contain an electrolyte formulation dominated by organic molecules that are highly flammable. This worsens the risk of thermal runaway – an uncontrollable process in which excess heat inside a battery speeds up unwanted chemical reactions that release more heat, triggering further reactions. Temperatures inside the battery can rise by hundreds of degrees in a second, causing a fi...