Samsung’s woes with the Note 7 and its messy recall are well documented, but lost amid that is that the only difference between a Note 7 and your average product with a lithium battery is that the Note 7 explodes more often. Apple itself had a problem with laptop batteries in the past. So this one image series of an iPhone 7 that exploded in the package shouldn’t terrify you. Well, yet, anyway.
An image series posted by Redditor Kroopthensnoop shows a coworker’s iPhone 7 arrive in pretty bad shape. It looks, for all the world, like the phone exploded inside the box during shipping. See the photos for yourself.
The results are dramatic, but this is a relatively low risk with lithium ion batteries. Remember that we’ve got billions of smartphones, laptops, and a litany of other products powered by these that have no issues. The issue is that the line between battery and bomb is about 10 microns thick. No, really, there’s an actual line between the cathode and the anode, the two crucial parts of your battery. Normally, the cathode and anode are separate and share electrons through the lithium salts in the electrolyte that bathes both of them. The charge is regulated by that lithium, so they don’t dump their ions all over each other all at once.
If that line, called a separator, is breached, then the cathode and anode can touch and share as many ions as they like, namely all of them. That causes them to heat up quickly, which engineers call “thermal runaway,” and, well, heat up a sealed vessel like a battery fast enough, and that pressure has to go somewhere, usually out the back of the phone. So, yes, this will occasionally happen, but at least, in this case, it happened in the box.