Been saying this a while. Anyone with an electronics background that also knows anything about chemistry
could tell you these Lithium Ion or polymer batteries are ticking time bombs, just waiting for an excuse to go off.
Usually there are 3 backups. 1 in the phone (or charging device) and 2 in the battery. The charging circuit, will
cut off current once it reaches the programmed level. The thermistor(s) in the battery, will tell the charging circuit
to stop the current flow, if the battery heats up to whatever the cutoff level is. And the fail safe, is the thermal fuse.
If all else fales, and the battery continues to heat up, the thermal fuse will melt in two pieces, which cuts off all
current flow (and requiring the battery to be replaced, it is a one shot device). But, if the thermal fuse is close to
the breakdown of the chemicals of the battery, it might be too late to prevent a thermal runaway.
If phone manufacturers would stop cow-towing to the "fashion designers" in Hollywood and make phones that aren't
"slim and stylish" for the lDIOT hollywood types that run around all the time with their phones in their hand, and start
"beefing up" the cases, it would provide enough ROOM inside a phone, to go back to a removable battery. The batteries
in non removable battery phones, typically do not have a protective plastic case surrounding them. That plastic case takes
up room, room that can be used to increase the capacity of the battery, which given the manufacturers silly idea of continuing
to increase the processor speed, screen density etc, need a bigger and bigger battery, in hopes it will make it through the
entire day, without needing charging.
Now, the problem is you combine a battery that can flex, that has as much capacity that they can squeeze into it, coupled with
a very thin casing, then, place said phone, in your tight jeans back pocket, front pocket, and sit down and get up a few dozen
times a day and that battery starts to flex. Once you break down the barrier shield that keeps everything separated (anode, cathode,
electrolyte) and they all get together, you end up with a thermal runaway.
People "think" they wanted thinner and thinner phones, because that's what the industry produced, and they go along like little sheep.
Now, you are stuck with non removable batteries, thin phones and the result is BOOM!
For Samsung's part, they tried to "one up" Apple, by releasing their phone, without really testing for durability. This time, it costs them