"Based on our investigation, we learned that there was an issue with the battery cell," a Samsung spokesperson explained in a note to Fast Company late Friday afternoon. "An overheating of the battery cell occurred when the anode-to-cathode came into contact, which is a very rare manufacturing process error."
In simple terms the anode pole (negative electrode) on a lithium-ion battery is where the power enters the battery from the charging apparatus. The cathode pole (positive electrode) is the point where the energy is slowly released after a chemical process takes place inside the battery. When the battery charges and discharges, ions shuttle between cathode and anode. Physical contact between those two poles can lead to a very rapid energy release—an explosion.
The Note 7 uses a 3,500 mAh fast-charging Lithium-Ion battery. As of September 1, 35 battery blowups have been reported through Samsung's customer service centers—17 in Korea, 17 in the U.S., and one in Taiwan. Samsung reportedly uses a different battery manufacturer for each major market is serves. We are waiting for more details from Samsung. MS