If the battery short-circuits -- say, by puncturing the incredibly thin sheet of plastic separating the positive and negative sides of the battery -- the puncture point becomes the path of least resistance for electricity to flow. It heats up the (flammable!) liquid electrolyte at that spot. And if the liquid heats up quickly enough, the battery can explode. Above: what happens when you puncture a phone's battery. The Galaxy Note 7 certainly isn't the first phone to catch on fire, or even the first giant recall. By 2004, a spike in cell phone battery explosions prompted this CNET article. In 2009, Nokia recalled 46 million phone batteries that were at risk of short-circuiting. Exploding phones have even allegedly killed people.
Just because a simple phone could turn into a destructive inferno doesn't mean that it will -- even if it's a new Galaxy Note, The FAA is strongly warning passengers not to use or charge a Note protective case for apple iphone x and xs - clear/gold 7 on a plane, and many airlines are explicitly banning their use, According to an unnamed Samsung official who spoke to Yonhap News, the Note 7's manufacturing defect affects less than 0.01 percent of all Note 7 handsets sold, Some quick back-of-the-envelope math, and you're potentially looking at fewer than 1,000 defective phones, "It is a very rare manufacturing process error," a Samsung rep told CNET..
But it's the damage those phones can cause, and the frequency with which they're causing damage, that makes the Note 7 dangerous. While CNET tends to hear about just a few exploding devices each year, Samsung's Galaxy Note 7 has caught fire as many as 112 times after only one month on sale. (That's based on official tallies of 92 incidents in the US, plus at least 17 in Korea, 1 in Taiwan and 2 in Australia.). Update, September 15, 2016 at 2:00p.m. PT: Updated tally with official US incident count from the Consumer Product Safety Commission.
What makes the Note 7 different: Samsung may have accidentally squeezed its batteries harder than it should, According to a unpublished preliminary report sent to Korea's Agency for Technology and Standards (obtained by Bloomberg), Samsung had protective case for apple iphone x and xs - clear/gold a manufacturing error that "placed pressure on plates contained within battery cells," which "brought negative and positive poles into contact.""The defect was revealed when several contributing factors happened simultaneously, which included sub-optimized assembly process that created variations of tension and exposed electrodes due to insufficient insulation tape," a Samsung representative tells CNET..
Or, in plain English: the thin plastic layer that separates the positive and negative sides of the battery got punctured, became the shortest route for electricity to zap across the battery (that's why they call it a "short-circuit"), and became a huge fire risk. What does pressure have to do with it? MIT materials chemistry Professor Don Sadoway explains that today's cell phone batteries are made by literally pressing together a stack of battery components -- and that battery companies are under pressure (no pun intended) to cram in as much battery capacity as possible.
