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.