|Fig. 1: Samsung Galaxy Note 7, the device that exploded numerous times causing a massive recall and ultimately the end of its production. (Source: Wikimedia Commons)|
On August 19th, 2016, Samsung Galaxy Note 7 (see Fig. 1) was released as a successor to Galaxy Note 5. With its IP68 water resistance, dual-sided curved display, iris recognition system, HDR color, and many other impressive features, the Note 7 broke pre-order records in South Korea, causing international releases to be delayed due to supply deficiencies.  Critics gave fairly positive reviews, praising for its HDR support and its streamlined user interface, while they criticized it for its very high price.  Dealing with these happy problems was short-lived, however, as Note 7s were recalled informally just two weeks after its release.
On September 2nd, 2016, Samsung suspended sales of the Note 7 and recalled some devices as manufacturing defect in the batteries caused excessive heating and caused fires.  Then, in just two weeks, Samsung issued a formal US recall and exchanged the phones with those with batteries sourced from different suppliers.  However, when these replacement phones caused issues as well, Note 7s were recalled worldwide and their productions were permanently stopped.  The Note 7s life had only spanned just less than two months before the permanent shutdown on October 11th, 2016.
The protagonist, or the antagonist, in this devastating story that caused injuries on Note 7 users and cost Samsung 6 billion dollars, was the Note 7 battery.  We will now examine the cause of the overheating and explosions by delving into this source of energy.
Before the first batch of recalls were made, Samsung had sealed a sizable 3500 mAh lithium battery into a rather thin 7.9 mm smartphone.  Although lithium battery explosion is specific to Samsung phones, 35 customers had reported severe overheating or explosions just after two weeks of the device's release.  In addition, around half of the batteries were made from a subsidiary called Samsung SDI, and some malfunctions in its manufacturing process created a misfit in the device.  As Samsung explains, the negative electrodes was deflected at the upper corner of the phone because of the pressure the big battery size on a small encapsulating phone.  Thus, these defections allowed these negative electrodes to come in contact with the nearby positive electrodes and create a short circuit. 
According to Samsung again, it made the grave mistake of revamping its Note 7 production after the first recall, thinking that the phones made with Amperex Technology were fine.  However, this sudden ramp up caused a number of manufacturing issues. Again, the phones were recalled, and Samsung had to ultimately take them out of production.  The high-wielding burrs on the positive electrode had penetrated the insulation taped the separator, which helps the positive and negative electrode to meet within the Jelly Roll.  This allowed the positive tab of the battery to directly interact with the negative electrode - short circuiting the board.  Additionally, this manufacturer for the second batch had made simple mistakes such as not applying insulation tape between the positive tab and the separator. 
In response to this horrible crisis, Samsung created a battery advisory group and a new quality assurance process called the 8-Point Battery Safety Check. Along with this, Samsung said it would contribute to the learning and processes for testing lithium ion batteries to global standardization bodies. 
© James Bai. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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