Lithium-ion batteries should remain stable and working, under normal conditions. However, if their terminals short-circuit either externally or internally, they can become extremely hot, and catch fire. Something similar may happen if an operator uses the wrong battery charger. But by then, it may be too late to remember that water does not extinguish lithium fires.
Water Cannot Extinguish Lithium-Ion Battery Fires
Lithium battery fires are occurring in garages and mobile homes in places as remote as the White Mountains in Arizona. Although these areas may escape the city scourge of lithium-ion-battery fires in scooters for a while longer.
The fires tax the resources of first responders, because the batteries behind them are very different from the lead acid batteries we manufacture:
- Our lead-acid batteries use a gel electrolyte solution containing distilled water and dilute sulfuric acid. The ions travel between lead plates, but the electrolyte cannot catch alight.
- Lithium-ion batteries are different. Their electrolyte comprises a solution of lithium and organic solvent. If this material overheats, it can catch fire that is difficult to extinguish.
Fires need oxygen to ignite and sustain. Traditional fire-fighting methods smother the flames so oxygen cannot reach them. But water does not extinguish lithium fires, because they generate their own oxygen.
How Lithium-Ion Battery Fires Generate Their Own Oxygen
Heat rises in a lithium-ion battery, following a short circuit resulting from misuse, or a technical failure, and can cause a spontaneous fire. The same heat also causes the metal oxides in the positive battery cathode to decompose, and release oxygen gas that feeds the flames.
This thermal runaway chain reaction can occur even if the battery is fully discharged, because chemicals generate the heat, as opposed to an external source. A lithium-ion battery fire can easily spread to other nearby flammable materials. Water or foam can deprive the secondary fire of oxygen, but not the initial battery fire.
We’ve had several battery fires, explains a fire chief in the White Mountain area. Rest assured we put water around the area, but not on the battery. That’s because it’s not going to extinguish the chemical reaction inside the battery, that’s actually causing the fire.
More Information
Thermal Gas Emissions in Lithium Batteries
Upward Spiral of Battery Thermal Runaway
