Li-Ion Battery Fire Extinguishers

What's the difference between Lithium and Lithium-Ion batteries?

Primary cell lithium batteries are non-rechargeable and mostly use lithium metal as their anode. For fires involving primary cell lithium batteries, a Class D L2 Powder Fire Extinguisher should be used, this is a specialist powder extinguisher designed specifically for use on combustible metal fires which includes lithium metal. It is important to note that water extinguishers should not be used on primary cell lithium batteries, as the water reacts with lithium metal which will make the fire significantly worse.

Secondary cell lithium-ion batteries are rechargeable and use a combination of different materials as their anode. For fires involving lithium-ion batteries, the most effective fire extinguishers contain an AVD (Aqueous Vermiculite Dispersion) solution such as the Lith-Ex range. However, unlike primary cell lithium batteries, lithium-ion batteries use lithium salts which contain only a very small volume of lithium metal, therefore you can effectively douse these fires with water.

Thermal runaway (lithium-ion batteries)

Thermal runaway is the name given to a process which is accelerated by increased temperature. It is mainly caused by a battery cell failure in lithium-ion batteries.

A simple failure in a battery cell can generate an increase in temperature, this creates a chain reaction in which more energy is released, further components of the battery break down which then fuels the fire with oxygen. This triggers an uncontrolled positive feedback loop where the temperature continually rises and further energy is released.

This process will often start with a single battery cell and the temperature of the fire will then cause other adjacent cells to break down, increasing the size and intensity of the blaze until all of the energy has been released. This process can be very quick or can last several hours.

Once the process of thermal runaway has begun, temperatures rise rapidly (within milliseconds) to an average of 400°C.