Credit: Journal of the Electrochemical Society
Abuse or manufacturing errors can cause a lithium ion cell to evolve gas, causing it to expand, or “pillow”. Abuse can take the form of overheating, overcharging, overdischarging, electrical short or physical abuse such as a forceful blow or bending. This process may continue with some combination of heat, smoke, flames & explosion. Perhaps most famously, in the recent events which lead to cessation of production & recall of Samsung Galaxy Note 7 phones.1,2,3,4
This much has been known for some time. Recently, a team at Canadian Light Source Inc., has used computed tomography (CT) scan technology to investigate what actually happens inside a cell failing in this way.5
Cross sections through a lithium ion cell produced by CT scans: (a) as manufactured (b) after overdischarge
(c) image difference map of the two scans with areas of expansion (gas formation) in red
Credit: Journal of the Electrochemical Society
Notice that areas of gas formation are frequently concentrated in irregularities in the manufactured cell. This suggests that improvements in manufacturing techniques can make cells less susceptible to this failure mode.
New Scientist
https://www.newscientist.com/article/2115413-x-rays-show-how-gas-pillows-make-lithium-ion-batteries-explode/?utm_medium=Social&utm_campaign=Echobox&utm_source=Twitter&utm_term=Autofeed&cmpid=SOC%7cNSNS%7c2016-Echobox#link_time=1481109691
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1 Hitchhiker’s Guide 2 Tech: “Samsung Galaxy Note 7 fires – cause – simple solution”, http://hhg2tech.blogspot.com/2016/09/samsung-galaxy-note-7-fires-cause-what.html
2 Hitchhiker’s Guide 2 Tech: “Samsung Galaxy Note 7 – fires continue – simple solution”, http://hhg2tech.blogspot.com/2016/09/samsung-galaxy-note-7-fires-continue.html
3 Hitchhiker’s Guide 2 Tech: “iPhone has fire too”, http://hhg2tech.blogspot.com/2016/09/iphone-has-fire-too.html
4 Hitchhiker’s Guide 2 Tech: “More lithium ion battery fires – not just phones”, http://hhg2tech.blogspot.com/2016/11/more-lithium-ion-battery-fires.html
5 Toby Bond et. al.: “Electrode Stack Geometry Changes during Gas Evolution in Pouch-Cell-Type Lithium Ion Batteries”, http://jes.ecsdl.org/content/164/1/A6158.full / Recipe for Swiss roll flambé Toby Bond Canadian Light Source battery has swollen up like an inflatable pillow LiIon lithium-ion lithium ion batteries battery cell cells ubiquitous phones laptops device devices tablets pad iPad hoverboards lightweight hold a lot of charge high charge density recent spate of explosions safety concerns batteries damage-prone damage prone structure Toby Bond Canadian Light Source synchrotron facility Saskatoon Canada Canadian Light Source Inc. Saskatoon, Saskatchewan S7N 2V3 Canada contain electrode sheets wrapped in a spiralling Swiss roll jelly roll configuration energy-producing layers causes problems gas forms inside gas build up battery becomes overheated overcharged left drained of charge for too long liquid components battery vaporise and produce gas causes external casing swell up resulting in the characteristic pillow appearance battery can either pillow small amount keep operating pillow a lot cease operation keep generating gas rupture cell explosion fire pillowing battery’s outer appearance looking inside high-powered X-ray technique called computed tomography CT scan process as gas built up electrode layers appeared buckle push apart subtle defects already present battery found to be points of weakness defects probably introduced assembly process suggesting improvements manufacturing make lithium batteries more resistant unclear whether pillowing involved recent battery failures Samsung Galaxy Note 7 phones reduce risk develop lithium-ion batteries no liquid components Neeraj Sharma University of New South Wales Sydney Australia working on solid-state batteries can be very safe scientific technical challenges need to be overcome compete with conventional lithium-ion batteries protect your lithium battery from pillowing stop it from overheating Avoid many uninterrupted hours playing 3D games your phone binge-watching movies nine-hour flight /
