Lithium Fires

Lithium batteries are a very economical source of power because of the very light nature of lithium itself.  However, lithium is a highly reactive substance. Lithium batteries are either rechargeable (Li-ion) or non-rechargeable (lithium metal). Like all batteries, lithium ones consist of two electrodes separated by an electrolyte. Typically for a lithium cell the electrolyte is a solution of lithium salts and organic solvents.

For Lithium-ion batteries, lithium ions are driven from the electrolyte into a carbon anode during charge. When the battery is discharged they flow back, creating a balancing flow of electrons in a circuit that powers the device.

The trouble comes about if there is a small fault or damage is caused to the extremely thin separators that keep the elements of the battery apart. This can lead to an internal short-circuit and a subsequent build-up of heat. This can trigger what is known as a “thermal runaway” in which the battery overheats and can burst into flame. That can cause adjacent battery cells to overheat. Lithium batteries can also be damaged by using them in hot environments and by excessive discharging and charging—which is why most lithium batteries contain special circuits to prevent this. Catching fire if something goes wrong, then, is in their nature. The two things that will keep lithium batteries relatively safe are continuous improvements in manufacturing techniques and the use of smart control systems to monitor their temperature and regulate their use. Besides a high energy density, another advantage of lithium-ion batteries is that they do not suffer from any “memory effect”, which means they can be partially charged and discharged many times without loss of capacity. Running down a lithium battery completely, however, can destroy it. So this too has to be guarded against by the power electronics.

What to do if there's a fire

For lithium-ion fires (lithium rechargeable batteries) the technique is to use water especially ensures the surrounding area is cooled too.

For lithium metal fires (primary batteries including the coin cell series) specialised techniques must be used.  In particular water, carbon-dioxide and sand extinguishers must NOT be used.  If in doubt, evacuate the building and leave the problem to the specialist emergency teams.  Do remember that extinguished lithium cells can re-ignite and they provide their own oxygen and fuel.

©Strand Europe Ltd 2013