Xiaomi to replace “explosive” Mi4i phone, issues an official statement on the matter2
Mr. Negi turned to Xiaomi to express his concerns regarding the incident, and now the company has responded with an official statement:
It is good to hear that Xiaomi is taking at least partial responsibility for what happened, offering a handset replacement to the affected party, but we'd still like to hear more about what might have caused the explosion in the first place. In any case, it seems like a malfunction has caused the battery of the phone to catch fire.
Exploding cellphone batteries have turned into the stuff of legends at this point. Stories about people who lost their hearing, sight, or a couple of fingers, while talking to a friend or browsing the Internet on their smartphone, are nothing new. The fact of the matter is, however, that exploding batteries are not that common of an occurrence.
Rechargeable lithium-ion batteries are at the heart of pretty much all modern tech. Most of them are designed with the possibility of a thermal runaway in mind – and other such issues that might arise with constant use – and employ different safety mechanisms to prevent them. At times, however, it is possible for these protection mechanisms to malfunction and, under the wrong circumstances, this could lead to the battery alleviating itself of the internal pressure buildup in a rather explosive fashion. Thermal runaway is caused when one portion of the battery gets too hot and can't cool down quickly enough, thus creating a chain reaction that generates an exponentially increasing amount of heat.
The battery in your smartphone can get too hot for various reasons. For example, using a device while charging it – which in and of itself is a process that generates heat – can up the internal temperatures quite a bit. You should be OK doing this, in theory at least, but many manufacturers advise against this practice. Using non-original batteries, shoddy off-brand chargers, exposing the device to direct sunlight and other sources of heat extensively, as well as prolonged charging are all possible reasons as to why a li-ion battery could malfunction. Most batteries of this type, as we mentioned before, are manufactured with safety mechanisms to prevent malfunctions that could cause external damage, and are capable of withstanding temperatures well above the recommended values, which has helped drastically reduce the number of serious accidents. Still, there is no such thing as a 100% fault-proof battery, and we would advise you to take caution in how you treat the one in your device.
via: XDA Developers