Click table to enlarge. Source: Samsung
The second article, from Medical Design Briefs, isn't specific to Samsung but does look at Li-ion battery packs. "Quality Assurance: Risk Mitigation for Lithium-Ion Battery Packs" looks at some of the test-process flow as well as standards that vendors of these batteries must adhere to in the test process. It also explains how test results are used as part of a quality-assurance feedback loop to understand and improve the product and process.
This is all good and important. But the underlying problem with batteries is that you can only examine them nondestructively as "black boxes" via their terminal voltage and current data, as well as temperature and physical dimensions. If you want to know more, you have to do an autopsy. Also, while aggressive steps such as punctures may enhance assessment of some failure modes, they don't provide insight into the thermal runaway mode that is of most interest (the Samsung batteries had not been physically abused).
But there is hope on the black-box front as well. A team at University College London (UCL) has developed a complex set-up that performed an internal computerized axial tomography (CAT) scan on lithium batteries in real time so they could see what's going on inside, Figure 1. How and what they did, and what they found, makes for a fascinating story, as it wasn't just a simple matter of borrowing an available CAT scanner; there's a synchrotron in the picture, as well as an interesting fixture.
Figure 1. (a) Cut-away of battery-containment design attached to the rotation stage for real-time X-ray CAT scan; (b) Arrangement of apparatus thermal runaway experiments; (c) 3D reconstruction with slices in the XY, YZ, and XZ planes of a 2.6-Ah battery (Cell 1) with isolated XY slice; (d) 3D reconstruction with slices in the XY, YZ, and XZ planes of a 2.2-Ah battery (Cell 2) with isolated XY slice. (Image and caption from University College London and Nature). Click image to enlarge.
You can get details of the story several ways: There's the detailed but hard-to-follow academic paper, with many excellent figures in Nature, "In-operando high-speed tomography of lithium-ion batteries during thermal runaway;" there's the overview by the research team, "Battery Safety;" and there is also the college's well-written press release with an attention-grabbing yet legitimate headline, "Tracking exploding Lithium-ion batteries in real-time." There's also an interview with the lead researchers in NASA Tech Briefs, "3D Imaging Reveals Battery Degradation in Real Time," which explains some of the issues they encountered and overcame with the test set-up — something that's rarely discussed in press releases or formal scientific papers but which is of interest to test engineers.
Getting new insight into subtle test and quality issues is difficult, especially when the "subject" doesn't easily give up its secrets, but with new instrumentation, configurations, ideas, and funding (of course), it may be doable.
What's on your list of things you'd like to see in a T&M setting, both literally and figuratively?