Samsung battery recall: why lithium-ion batteries catch fire
Samsung's not the first tech company to face exploding batteries
But despite the danger, lithium-ion batteries are how we power our mobile devices, from laptops to smartphones and cameras. There's good reason for that, as surprising as it may sound after stories of children with burned hands and cars burning up.
But while researchers and manufacturers have worked to improve their safety and build fire prevention systems, alternative materials are also being considered. Is it time to give up lithium-ion for something less efficient, more expensive but safer? Samsung and the owners of the flame-destroyed Jeep might think so after the Galaxy Note 7 recall.
Here's what you need to know about lithium-ion batteries and why now and then they go up in flames.
Why do lithium-ion batteries explode or catch fire?
The cause of lithium-ion battery fires depends on the hardware and can vary by case, notes Professor Clare Grey, of the University of Cambridge's department of chemistry. "The source of the short circuit is likely different with these different battery incidents, but the driving force for the fires and explosions is the same," said Grey.
"The source of the fires is generally a short circuit between a highly oxidised cathode (positive electrode material) and anode (negative); this results in a very fast reaction between these two solids, which causes rapid heating," she explains. "When the battery gets hot enough the separator, which physically separates the cathode and anode melts, and even faster heating occurs (so-called 'thermal run-away')."
She adds: "The charged cathode material is not stable, and so onheating, it loses oxygen. The oxygen can then react with the organic electrolyte." And that leads to an explosion or fire.
In the case of Samsung's phablet, the batteries are catching fire when charging, so that suggests a different problem than with previous laptopfires when batteries caught fire "just sitting there," she added. And that could mean though Grey stressed it was speculation that such laptop fires are caused by small bits of metal getting caught in the battery during manufacturing.
Why do we use lithium-ion batteries in all our gadgets if they can go up in flames?
As Grey puts it: "They are simply so much better than anything else out there, in terms of energy density on both a volumetric andgravimetricbasis."In other words, you get more charge for the battery's size and weight than competing materials and both are key to keeping our smartphones slim and light.
Indeed, the energy density in lithium-ion batteries is twice that of standard nickel-cadmium versions, according to the websiteBattery University, plus they're "low maintenance." That means they don't need prolonged "priming" before they're used you can charge them to full once, and they're good to go and they don't have "memory", so you don't need to discharge them now and then to keep them fresh.
What else could we use?
The main rival to lithium-ion is nickel-cadmium, but they require multiple cells and have half the energy density of the former.
"There are cathode materials out there already such as LiFePO4, which are safer and less prone to O2 loss," said Grey. "But consumers would have to accept a battery with a lower energy density."
And more research is on the way. Universities in Japan have made progress on solid-state batteries, an idea Dyson invested in earlier this year with its acquisition of solid-state startup Sakti3. British startup Faradion is working on a sodium-ion battery, but they may not make the leap to gadgets as they have less energy density and shorter recharge life."It is possible to commercialise sodium-ion batteries but whether it will become a profitable business that outperforms lithium-ion batteries is a different matter," Shinichi Komaba, a professor at Tokyo University of Science working on the technology, told theFinancial Times.And others are looking at lithium-air and lithium-sulphur batteries, though more for use in electric cars.
And that's only a small slice of the research into batteries. "There is work in research labs in universities and companies to replace the organic electrolyte with less flammable liquids (electrolytes) or to replace the liquid completely by a ceramic," added Grey.
Can we fix lithium-ion batteries?
They're already better than they used to be. Grey pointed to more care taken in manufacturing, improved separators that have higher melting points, and coating the cathode materials to improve stability. Plus, hardware makers have developed better controls for the charging protocols. "Manufacturing has got much better and there are fewer flaws and recalls but it's still a challenge," she said.
There's also research into "self-healing separators" that would close any holes that form to avoid leaking materials or batteries that shut down if they heat up too much. "It all adds to the cost of the battery - but the battery is a smaller fraction of the cost of a smartphone than it was for an earlier mobile phone, so perhaps it's time to tolerate extra cost for safety," she added.
That said, lithium-ion battery fires remain rare, and with such improvements, are getting safer all the time.
What should you do in case of a fire?
If you're using a device with a lithium-ion battery, and it starts to hiss or bulge, unplug it from the mains, remove the battery from the gadget if that's possible, and move it away from anything flammable, advises Battery University.
"A small Li-ion fire can be handled like any other combustible fire," it adds, so have your Class-D extinguisher at the ready, but water or even soda is also fine to use. "Water-based products are most readily available and are appropriate since Li-ion contains very little lithium metal that reacts with water. Water also cools the adjacent area and prevents the fire from spreading. Research laboratories and factories also use water to extinguish Li-ion battery fires."
If a splash from your drinking glass isn't doing the trick, you may just need to let it "burn out". If the fire is from a larger battery, such as an electric vehicle, don't use water that'll just add to the problem, as the higher lithium count will react with the fire. The fumes that come from a burning lithium-ion battery is mainly carbon dioxide.
Should batteries be allowed on flights?
Good luck prying smartphones and tablets out of air travellers' hands, but Samsung's Galaxy Note 7 has been banned from some airlines, while US and Canadian air authorities have advised airlines be wary.
But it's not only the exploding Samsung device that's a concern. At the beginning of the year, the US Federal Aviation Authority (FAA) warned that lithium-ion or similar batteries had the "potential risk for a catastrophic hull loss" when held in checked bags. The warning only applies to batteries "not contained in or packed with equipment".
The FAA said that a single lithium battery burning up in the cargo hold could ignite others, and it knows, as it tested it out. "In 2015, FAA Tech Center testing showed that the ignition of the unburned flammable gases associated with a lithium battery fire could lead to a catastrophic explosion," it notes, adding that the current fire suppression systems would be "incapable of preventing an explosion".
As noted by a terrifyingNew York Times article really, don't read it on your Samsung during take-off there's been no airline crash down to passengers' gadgets, but cites the Royal Aeronautical Society as pointing out that the sheer number of batteries we bring with us on our travels means the maths are not in our favour.
The NYT report suggests air authorities are starting to track in-flight incidences of battery fires, with Australia's International Air Transport Association uncovering 24 cases and the FAA spotting just 19 in the past five years though the article says if you ask pilots or flight attendants, they'll tell you it's a monthly occurrence.
Because of that, it's advisable to keep your devices and spare batteries with you in your carry on at least that way if they spark up, you can do something about it, and the materials planes are made from are seriously fire retardant, which isn't the case with the clothing in your suitcase.
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