The battery that can extinguish itself

Scientists have developed a lithium-ion (li-ion) battery that contains a fire-extinguishing element which is released if the battery overheats

Fire hazard: Lithium-ion batteries will catch fire or explode if overcharged or if internal malfunction causes short circuit – condition known as thermal runaway

Oct 11, 2016: Samsung ceases production of its new Galaxy Note7 smartphone following spate of exploding handsets – believed to be caused by faulty li-ion batteries

LI-ION BATTERY (schematic illustration)
Anode (Carbon) Negatively charged electrode

Cathode (Cobalt) Positively charged electrode

Discharge: Current flows from anode to cathode through device it is powering BMW i3 electric supermini

Electrolytes: Flammable solution

Separator: Positively charged lithium ions travel from anode to cathode through electrically insulating microfibre separator

New smart separator

SEPARATOR MICROFIBRE
Triphenyl phosphate (TPP) flame retardant contained within protective polymer shell

Shell melts if battery gets too hot, releasing TPP into electrolyte fluid, extinguishing fire in 0.4 seconds

Shell   TPP core

Market pressures: Li-ion batteries considered promising power source for electric vehicles. But as demand for battery density increases, so dangers of thermal runaways rise

Number of li-ion batteries made every year 5 billion


Sources: Stanford University, AAAS, wire agencies