................................................................................................................................................
Exploding Lithium-Ion Batteries
Why Do Lithium-Ion Batteries Explode?
HARRY GUINNESS
@harryguinness
While lithium-ion
batteries are, on the whole, incredibly safe they do very very occasionally
catch fire or explode.
When it happens,
like with Samsung’s Galaxy Note 7 fiasco or HP’s more recent laptop recall, it’s always big
news.
So, what’s going on
and why do batteries sometimes go out with a bang? Let’s find out.
Rechargeable
lithium-ion batteries — the kind of battery that’s inside your laptop, phone,
tablet, and pretty much every other modern gadget you own, as well as electric
cars and airplanes — are responsible for the portable device revolution.
Without lithium-ion
batteries, I wouldn’t be able to write this article sitting in a coffee shop;
instead, I’d need to be plugged into a power source the whole time.
What’s Inside a Lithium-Ion Battery?
To understand why
lithium-ion batteries sometimes fail, you need to know what’s going on under
the hood.
Inside every
lithium-ion battery, there are two electrodes — the positively charged cathode
and the negatively charged anode — separated by a thin sheet of
“microperferated” plastic that keeps the two electrodes from touching.
When you charge a
lithium-ion battery, lithium ions are pushed by electricity from the cathode,
through the microperferations in the separator and an electrically conductive
fluid, and to the anode.
When the battery
discharges, the reverse happens with the lithium ions flowing from the anode
toward the cathode. This is the reaction that powers your laptop.
Small batteries,
like those found in smartphones, usually have only a single lithium-ion cell.
Larger batteries,
like those in laptops, normally have between 6 and 12 lithium-ion cells.
The batteries in
electric cars and airplanes can have hundreds of cells.
What Makes a Lithium-Ion Battery Explode?
The very thing that
makes lithium-ion batteries so useful is what also gives them the capacity to
catch fire or explode.
Lithium is really
great at storing energy. When it’s released as a trickle, it powers your phone
all day.
When it’s released
all in one go, the battery can explode.
This lithium-ion battery from a Japan Airlines Boeing
787 caught fire in 2013.
Most lithium-ion battery
fires and explosions come down to a problem of short circuiting.
This happens when
the plastic separator fails and lets the anode and cathode touch. And once
those two get together, the battery starts to overheat.
There are a number
of reasons that the separator can fail:
· Bad Design or Manufacturing Defects: The battery
is poorly designed, as with the Galaxy Note 7. In that case, there
wasn’t enough space for the electrodes and separator in the battery.
In some models,
when the battery expanded a little as it charged, the electrodes bent and
caused a short circuit.
Even a well
designed battery can fail if quality control isn’t kept tight enough or there’s
some defect in manufacturing.
· External Factors: Extreme heat is nearly
guaranteed to cause a failure. Batteries left too close to a heat source — or
caught in a fire — have been known to explode.
Other external
factor can cause a lithium-ion battery to fail, too.
If you drop your
phone too hard (or too many times), there’s a chance you’ll damage the
separator and cause the electrodes to touch.
If you pierce the
battery (either by accident or deliberately), then you’ll almost certainly
cause a short circuit.
· Charger Problems: A badly made or poorly
insulated charger can also damage a lithium-ion battery.
If the charger
shorts or generates heat near the battery, it can do enough damage to cause
failure.
That’s why we
recommend using only official chargers (or at the
very least, high quality third party ones from reputable brands).
Lithium-ion
batteries do have built in protections to stop them overcharging.
While very rare, if
these safety precautions fail, overcharging is a good way to overheat a
battery.
· Thermal Runaway and Multiple Cells: While not
relevant to single cell batteries like those found in most smartphones (the
iPhone X actually has two cells), only one battery cell needs to fail for the
whole battery to go.
Once one cell
overheats, you get a domino effect called “thermal runaway.”
For batteries with
hundreds of cells — like those in the Tesla Model S — thermal runaway has the
potential to be a really big problem.
Even though
examining why battery sometimes fail paints a frightening picture, lithium-ion
batteries are a safe and mature technology.
The fact that it’s
always news when a battery explodes unexpectedly shows how rare an event those
big failures are.
Battery
manufacturers put a lot of safeguards in place to prevent batteries failing, or
at least mitigate the damage a failure can cause.
HARRY
GUINNESS
Harry is
How-To Geek's resident normal and photography expert. When he's not using
photography as an excuse to travel, ski, sail, stay up late, and otherwise
dodge the real world, he's teaching people how to use their cameras to take
great photos.
Harry's main
area of interest is himself, which is why self-portraits grace many of his
articles. He also likes books, movies, the outdoors, and Justin Pot.
Other
than How-To Geek, Harry's work has appeared in newspapers like The
New York Times and on Popular Science, Medium's OneZero, Lifehacker, Envato Tuts+, MakeUseOf, and a
host of other technology sites. His photos have been published on hundreds of
websites, normally without his consent. You'll find him sharing tips from his
life experiences over at LifeSavvy, How-To
Geek's sister site.
Unlike
Chris Hoffman, he's verified on Twitter.
About
How-To Geek
How-To
Geek is an online technology magazine and one of the top 500 websites in the
US. Since it was created more than a decade ago, the site’s 10,000+ in-depth
articles have been read over 1 billion times. More than 15 million people read
our articles every month.
We're
the people you turn to when you want someone to explain technology, whether
that means detailed troubleshooting guides or in-depth explainers on the latest
tech. Our team of expert writers and editors have decades of experience in
journalism and technology. Beyond the web, they've written books for publishers
like Microsoft Press and have been published in print magazines like PCWorld
and Consumers Digest.
How-To
Geek has been recommended as an expert resource by industry groups like the
Wi-Fi Alliance and newspapers like The New York Times. Organizations like the
BBC and Wirecutter have directed their readers to us for our helpful tutorials.
Our writers have been interviewed as experts on TV and radio programs. We're an
independent company that remains fully owned by our founders, too.
No comments:
Post a Comment