What are the possible reasons behind this? Let's have a look on them.
Blasting of phone's battery isn't any new news. We have been hearing about such incidents since a decade. Earlier it was Nokia Phones. If you could recall, in those time BL-5C Batteries of Nokia phones were catching fire. Then, news of Galaxy Core blasting were coming. And now same thing is going on with Galaxy Note 7.
The simplest reason for this is short circuit in the battery. Almost all phones use Lithium-Ion Batteries. This batteries work on electrolytic principle. We used to study about this in school. There is an electrolytic solution in which two electrodes: Anode and Cathode are dipped. Chemical reactions occur and electrons start accumulating on Anode. Due to this an electric difference is created between Anode and Cathode. So electrons try to rearrange themselves and move to cathode.
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| Souce -CIE.Washington.EDU |
But electrons don't go to cathode straightaway because this motion is restricted by the electrolytic solution. When a wire is connected between the Cathode and Anode, the circuit gets completed and electrons move to cathode through that wire. Hence, we get a potential difference.
The electrolytic solution used in Lithium-Ion batteries is very flammable and can catch fire easily. There is a very thin layer between positive and negative side in the battery which keeps them separate. If somehow this thin layer gets punctured, short-circuit happens and the resistance at this point will be very less for electricity to flow. Due to this, the flammable liquid in electrolyte starts heating at that point and if the heat increase is too rapid, the battery explodes.
So why use Lithium-Ion Batteries if the electrolyte used in them is so flammable? The answer is - Because Lithium-Ion batteries are more compact and can be made lightweight compared to others. So, a possible reason for the exploding of batteries could be that during manufacturing, the batteries might have been squeezed too much to keep it compact. As Samsung has said "It's a manufacturing defect."
According to one report of Bloomberg, during manufacturing of Samsung batteries, the pressure given on them was to high due to which negative and positive poles came in contact. And in simple words, the thin layer between them got punctured which led to short-circuit and eventually a blast.
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| Source -How Stuff Works |
This could be a possible reason for explosion. We still have to wait for official statement of Samsung for actual reason. Samsung had made somewhat about 2.5 million handsets out which 1 million were already sold. Although Samsung, has recalled all its sold Note 7s and has stopped its shipment and sales.
But according to a report by Yonhap News, this manufacturing defect was only present in 0.01% of total manufactured handsets which tells that the defected handsets were less than 1000. So, lets wait for Samsung's Official Statement to know more about this.
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