As Samsung prepares for yet another recall of the Galaxy Note 7, as well as to bury the Galaxy Note 7 entirely, the world is no doubt wondering just what has happened to the Galaxy Note 7 that a massive corporation like Samsung would have made the same mistake twice. At first, it was reported that batteries from their own subsidiary of Samsung SDI were to blame, and that they would be using batteries from China's ATL firm to get the "safe" units on shelves and into the hands of loyal customers. While that appears to have happened, this new batch of Galaxy Note 7 devices were not only overheating, but they were doing so without warning, even when they were simply left to their own devices. Now, according to reports from Korean media, it looks as though the design of the phone itself could be to blame.
SBS has taken a look at both the Samsung SDI and ATL batteries under a microscope, and the one from Samsung SDI can be seen with isolation plates too close to the edge of the battery pack and as these are compressed under pressure, the anode-to-cathode defect that Samsung reported back in September is set into motion. The images below show the comparison to the Samsung SDI battery and the Chinese ATL battery, but given that the second batch of Galaxy Note 7s were to use the ATL battery, this isolation plate issue should have been negated. The answer to why these new units are catching fire as well could lie within the design of the Galaxy Note 7 itself. Samsung was very proud of the fully-symmetrical design that the glass curve plates on the front and back of the device achieved, and while it no doubt looked great in person, it could have put the internal battery under a lot of pressure. The Galaxy Note 7 is even narrower than the original 5.3-inch model launched back in 2011, and with 7000-series aluminum alloy, that's 1.3x times stronger than that found within the Galaxy S7 Edge, it's not hard to see that the internal components were under a tight squeeze. Add on top of this a tight seal to give the Galaxy Note 7 its IP68 rating to protect it from water, and the battery pack is put under even more pressure.
This theory has yet to be confirmed by Samsung, and it probably never will. The Galaxy S7 Edge is a phone with a sizable 3,600 battery inside of a device that's just 7.7mm thick. The Galaxy Note 7 features a 3,500 mAh battery inside a frame that's 7.9mm thick, but is much more narrow than previous versions, all the while making room for the S-Pen as well as the other internal components that make up the device. With all of this going on, there's little room for the battery when all's said and done, and once a battery gets hot, things start to become a little dangerous and with little room for this heat to dissipate, this tight squeeze could have been the reason behind these explosions and fires.