Earlier this week, Samsung announced the results of their investigation into the Galaxy Note 7 failure. The Galaxy Note 7 phones spontaneously caught fire, leading to a recall of approximately 2.5 million devices and losses of over $2 billion dollars. Though the initial defective phones were recalled, their replacements also began to catch fire, spawning an investigation by Samsung.
Anatomy of a Lithium-Ion Battery. Source: Samsung
According to an internal investigation aided by outside experts, the root cause of the failure was battery short circuits. Of the two companies that supplied batteries for the Galaxy Note 7, both had separate issues ultimately leading to fires.
Battery “A”, the original battery, suffered from a deformation in the negative electrode that caused it to touch the positive electrode. The deformation was caused by a design flaw in the pouch (a “case” surrounding the battery components) that did not allow sufficient space for the battery components to expand and contract during charging and discharging cycles. This caused the negative electrode to become bent; weakening a component designed to keep the positive and negative electrodes from touching, eventually allowing the positive and negative electrodes to come into contact.
Battery “B”, the replacement batteries, failed due to a welding issue on the positive tab. A small piece of welding material was left sticking out and was enough to perforate the separator that keeps the positive and negative electrodes from touching, causing a short circuit. The short circuit caused temperatures high enough to melt copper elements inside of the phone.
Samsung said it is implementing an 8-point battery safety check intended to ensure the quality and safety of its products going forward.
Samsung’s battery issues highlight several areas broader than the battery technology field. Having a robust quality system in place that encompasses vendors, incoming components, internal procedures and final product quality is essential to avoiding the situation in which Samsung found itself – high-profile and dangerous field failures of its products. One specific aspect of such a quality system would include sufficient reliability testing of both components and final assemblies to catch potential failure modes before a product is released. Whether failures are discovered during internal testing or during service, detailed failure analysis to determine the root cause of the failures is essential to reaching a solution.
Cambridge Polymer Group identifies opportunities for quality system improvements, designs and implements effective reliability testing, and conducts failure analysis employing a variety of analytical techniques and multi-disciplinary professional expertise. Ensure your products perform to your customers’ satisfaction, minimizing the risk of embarrassing field failures.