LITHIUM-ION BATTERY EXPLOSIONS, EXPLAINED
The company reported at least 35 cases of combustions from a manufacturing error
Lithium-ion batteries show up in all sorts of tech, from phones and laptops to airplanes and electric vehicles. But a voluntary recall of some 2.5 million Samsung Galaxy Note 7 smartphones after reports of battery explosions is raising concerns about their safety.
Last week, the Federal Aviation Authority (FAA) warned passengers not to turn on or charge the devices during flights — or even put them in checked baggage. Some international airlines have placed similar restrictions on the smartphone. The U.S. Consumer Product Safety Commission advised consumers “to stop charging or using the device.”
Here’s why the lithium batteries that probably power a lot of your tech sometimes catch fire.
Why are lithium-ion batteries so popular?
Lithium-ion batteries are different from basic AA’s. They’re rechargeable, often built directly into devices and rely on the chemical lithium as primary fuel.
Lithium-ion batteries are popular in devices because they store energy efficiently and are slow to lose their charge.
“You get a lot of oomph relative to older technologies that were the same size — often two to four times the voltage,” explained Stephen Hackney, a professor of materials science and engineering at Michigan Tech University.
How do they work?
Lithium-ion batteries work by storing energy and releasing it through controlled chemical reactions. A lithium-ion battery has two electrodes — places electricity can enter or leave the battery — on opposite sides.
One electrode, called the anode, is filled with negatively charged ions. The other electrode, a cathode, contains positively charged ions and lithium. Think of the anode and cathodes like the plus and minus signs you often see on batteries.
When you use a battery, the lithium moves from the cathode to the anode — and when charging, the lithium moves back to the cathode. A separator inside keeps the anode and the cathode from touching because that can trigger mishaps such as fires and explosions.
So, what can cause the explosions?
The reason lithium-ion batteries can store so much power is that lithium “wants to react to almost anything” — which can lead to explosive results, Hackney said.
But one of the most common reasons the batteries explode is because of mistakes in the charging process, he said. Inside the devices is software that tells them exactly how much the batteries should be charged and how fast. If those protocols are set incorrectly, it can destabilize some chemicals inside the battery and cause a chain reaction that researchers call a “thermal runaway” that may lead to fire or explosions. Overheating can also cause explosions.
Another reason could be shoddy manufacturing or rough user treatment. If unwanted materials, like scraps of metal, accidentally end up inside the battery, they can set off a thermal runaway. So could dropping a device if the impact causes a break in the separator between the anode and cathode.
What happened with the Galaxy Note 7?
It seems like a manufacturing problem. The company reports at least 35 cases where the batteries combusted due to “a very rare manufacturing process error” in which the anode and cathode touched, the company said in a statement on its U.K. website.
The company decided to temporarily pull the phone off the market just two weeks after its release and is offering replacements to those who already purchased the device.
How often do these problems occur?
The good news, according to Hackney, is that these types of problems are pretty uncommon, especially among high-end devices, when manufacturers keep a close eye on production quality.
But there have been high-profile cases. In 2006, Dell recalled more than 4 million laptop battery packs over combustion issues. In 2013, the FAA grounded the Boeing 787 Dreamliner after reports of fires related to the lithium-ion batteries used in the planes.
And half a million hoverboards, one of the hottest gifts of the last holiday season, were recalled this summer because of lithium-ion battery explosions.
Are regulators looking into these batteries?
The government and international organizations regulate lithium-ion batteries in many ways, which is probably one reason we don’t see more explosions. For example, the Department of Transportation has rules for shipping the batteries safely.
Other U.S. regulations call for batteries in consumer goods to undergo safety tests, and the Consumer Product Safety Commission has overseen recalls involving products with lithium-ion batteries that were deemed hazardous. The agency is working with Samsung on a formal Galaxy Note 7 recall in the United States.