Samsung Electronics announced
on Friday that it would recall 2.5 million Galaxy Note 7 smartphones after
finding a flaw in the battery cell that resulted in fires. It is the latest
problem for the lithium-ion battery, the power source at the heart of most
modern devices.
Q. What is a lithium-ion battery?
A. It is a powerful, lightweight
battery that includes lithium-ion
particles. Lithium-ion particles in the batteries move back and forth between a
negative and positive electrode as they are charged and discharged. The
advantage for companies in Silicon Valley and Detroit is that the batteries
don’t take up much room and can quickly recharge repeatedly without wearing
out.
Q. What are they used in?
A. Chances are you
encounter these on a daily basis. They are in smartphones, laptops, electric cars, airplanes and even e-cigarettes. Of
course, the ones in airplanes and cars are much larger than those used in
phones.
Q. What is the problem with
lithium-ion batteries?
A. To ensure that the
lithium-ion particles can move easily between electrodes, volatile and
flammable chemical compounds are pressurized inside battery cells. The problem
is that when a battery is charged and recharged, it generates heat. If that
heat is not controlled properly, it can cause the compounds inside the battery
to burst into flames or even explode. Those compounds can become similarly
unstable if something punctures the battery cell.
Q. What happened with the Samsung
phone?
A. Samsung said it
thought the problem came from a “minute flaw” in the production of the
batteries. One theory was that a part inside the battery was coiled
incorrectly, causing more stress.
Q. What does the recall cover?
A. Samsung says it
will replace phones in 10 countries where the device is sold and that it will
take about two weeks to manufacture the replacements.
Q. What other products have had
issues with the batteries?
A. The batteries have
caught fire inside smartphones, laptop computers,
electric cars, hoverboards and airplanes.
Boeing’s 787
Dreamliners were grounded in 2013 after a lithium-ion battery caught fire in
Boston. That same year, the batteries in Tesla’s electric cars came under scrutiny after at least two fires.
In May, the
Transportation Department banned the use of battery-powered e-cigarettes on flights
and their inclusion in checked baggage. In July, more than a half-million
battery-powered hoverboards were recalled after at least 60 fires.
Q. If the batteries are problematic,
why do companies continue to use them?
A. Battery
technology has been slow to advance, largely because the products must pass
rigorous safety testing. Lithium ion has proved to be low-cost and easily
reproducible. And over all, they are pretty safe. While the fires and
explosions are vivid, the incidents are rare, considering how many lithium-ion
batteries are made and sold every year.
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