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.
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
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