Manufacturers

History recalls how great the fall can be

While everybody’s sleeping, the boats put out to sea

Borne on the wings of time

It seemed the answers were so easy to find

Roger Hodgson, Supertramp, from Fool’s Overture, 1977

MWC 2017 is over. The crowds came and saw ideas and innovations. The media covered and reviewed. Awards were made. Yet a sense of public amnesia seemed to hover over the battery safety problems that the Samsung Note 7 brought to surface in 2016. Yes, Samsung shows the deep scars of these fateful days. Yes, there is a real fear among the device manufacturers. And yet, the fear and concerns are also accompanied with a sense of paralysis, a sense of a rudderless ship when it comes to safety, and a sense of wishful thinking that the Note 7 fires were an aberration in time that the industry will put behind it.

Samsung announced this week the results of their investigations regarding the Galaxy Note 7 fires. Samsung hired three independent test laboratories, Exponent, TUV Rheinland and UL to perform the analyses. The result was three full reports and presentations with technical details, mostly written by engineers for engineers. Vlad Savov at The Verge called the reports “humble and nerdy.” I can hear many in the audience screaming: “Translation, please!” I will try in this post to simplify and summarize the findings.

Of the three reports, the one written by Exponent is the one that offers the most useful pointers into what went wrong with the Note 7 batteries.  Here’s what it said, in simple terms.

It was the best of times, it was the worst of times. It was the age of innovation, it was the age of imitation. It was the epoch of the battery, it was the epoch of lithium. It was the season of Japan, it became the season of China. It was the spring of hope for batteries, it was the winter of despair from safety. Charles Dickens will forgive me for contorting his famous novel into a Tale of Two Geographies: China vs. the world, that is in lithium-ion batteries, of course.

This year has been one of heightened awareness regarding battery safety. Smartphone manufacturers now realize that battery fires are real and recalls from the field are enormously expensive. Along with this education comes a deeper realization that battery quality and the presence of hidden defects are very serious matters.

Today’s post sheds light onto the challenges of battery manufacturing and ensuing defects. These discussions are not useless academic conversations. We see manufacturing defects in batteries especially those sourced from Chinese manufacturers. We observe them more frequently in batteries with high energy density where manufacturing tolerances are challenging.

A recent article published by The Verge attempted to explain the science behind the exploding Samsung Note 7 batteries. The article touches on several important aspects of battery safety but the handwaving did not really talk about much science. So this post will address a failure mode of lithium-ion batteries and how defects can form during manufacturing with catastrophic results.