Lithium-ion batteries, such as this laptop battery, pack considerable energy into a compact, lightweight space. The batteries are very safe, but certain conditions can trigger an explosion or fire. |
Lithium
Batteries
Why Lithium Batteries Catch Fire
Fire and Explosion Risks of Lithium Ion Batteries
by Anne Marie Helmenstine, Ph.D.
Lithium batteries are
compact, lightweight batteries that hold considerable charge and fare well
under constant discharge-recharge conditions.
The batteries are found
everywhere -- in laptop computers, cameras, cell phones, and electric cars.
Although accidents are rare,
those that do occur may be spectacular, resulting in an explosion or fire.
In order to understand why
these batteries catch fire and how to minimize the risk of an accident, it
helps to understand how the batteries function.
How Lithium Batteries Work
A lithium battery consists of two electrodes separated by an
electrolyte.
Typically, the
batteries transfer electrical charge from a lithium metal cathode through
an electrolyte consisting of an organic solvent containing lithium salts over
to a carbon anode.
The specifics depend on the
battery, but lithium-ion batteries usually contain a metal coil and a flammable
lithium-ion fluid. Tiny metal fragments float in the liquid.
The contents of the battery
are under pressure, so if a metal fragment punctures a partition that keeps the
components separate or the battery is punctured, the lithium reacts with water
in the air vigorously, generating high heat and sometimes producing a fire.
Why Lithium Batteries Catch Fire or Explode
Lithium batteries are made deliver a high output with minimal
weight.
Battery components are
designed to be lightweight, which translates into thin partitions between cells
and a thin outer covering.
The partitions or coating are
fairly fragile, so they can be punctured. If the battery is damaged, a short
occurs. This spark can ignite the highly reactive lithium.
Another
possibility is that the battery can heat to the point of thermal runaway. Here,
the heat of the contents exerts pressure on the battery, potentially producing
an explosion.
How to Minimize the Risk of Fire or Explosion
The risk of fire or explosion increases if the battery is
exposed to hot conditions or the battery or internal component is compromised.
You can less the risk of an
accident by:
· Avoiding
storing at high temperatures. Don't keep batteries in hot vehicles. Don't allow
a blanket to cover your laptop. Don't keep your cell phone in a warm
pocket. You get the idea.
· Avoid
keeping all your items containing lithium ion batteries together.
When
you travel, especially on a plane, you'll have all your electronic items in one
bag.
This
is unavoidable because the batteries have to be in your carry-on, but usually,
you can keep some space between battery-containing items.
Although
having lithium ion batteries in close proximity does not increase the risk of a
fire, if there is an accident, the other batteries can catch fire and make the
situation worse.
· Avoid
overcharging your batteries. These batteries do not suffer "memory
effect" as badly as other types of rechargeable batteries, so they can be
discharged and recharged many times nearly back to their original charge.
However,
they do not fare well if they are completely drained before recharging or are
over-charged.
Car
chargers are notorious for overcharging batteries. Using any charger other than
the one intended for the battery can increase risk of damage.
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