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Donut Lab's 'Solid-State' Battery Exposed As Regular Li-Ion

Slashdot
1 month 3 weeks ago
A battery researcher's investigation, backed by more than 20 independent experts, claims Donut Lab's much-hyped "solid-state" battery is actually a conventional lithium-ion cell, with voltage curves and expansion data matching high-nickel NCM chemistry rather than the promised sodium-ion solid-state design. Electrek reports the company raised about $25 million from more than 1,300 mostly small investors on claims of 400 Wh/kg energy density, 100,000-cycle life, and 5-minute charging that now appear unsupported. From the report: The investigation consulted over 20 independent battery experts, including Julian Zanau from the Fraunhofer Research Institute, Dr. Yahim San from Justus-Liebig University, Tom Bicha from Leona, and Dr. Yuo Hesca from Seinajoki University of Applied Sciences. Every single one confirmed the tested cell is lithium-ion. There are two key pieces of evidence. First, the voltage curves from VTT testing match high-nickel lithium-ion cells (NCM chemistry). The cell sits at 3.7-3.8 volts at 50% state of charge -- right where lithium-ion cells operate. Sodium-ion cells don't go significantly past 3.5 volts at 50% SOC. The second piece of evidence is even more damning: VTT's cell expansion data. When a battery charges, ions squeeze into the anode material, causing it to expand in a predictable pattern. A graphite anode produces a distinctive "kink" in the expansion curve around 50-70% state of charge, caused by how ions reorder themselves in graphite's layered structure. The Donut Lab cell shows exactly that kink. This is critical because sodium ions are physically too large to fit into graphite layers. The graphite anode signature proves the cell uses lithium ions. The investigation puts it well: "it's like we have a slightly noisy fingerprint and a picture of the suspect's face. And yet again, it's a match." The calculated energy density? About 298 Wh/kg -- what you'd expect from a good lithium-ion cell, not the 400 Wh/kg claimed. The investigation reveals that the battery technology traces back to CT Coatings, a German company with an "eclectic" array of patents -- including inventions for screen-printed paving slabs, menu folders, and warning triangles. CT Coatings promised Nordic Nano and Donut Lab a screen-printed sodium-ion solid-state battery. What it delivered was a lithium-ion pouch cell.

Read more of this story at Slashdot.

BeauHD

CodeSOD: Driven Development

The Daily WTF
1 month 3 weeks ago

We should always be wary of "(.+)-driven development". Things like test-driven development, or domain-driven development are fine, but they're also frequently approached from a perspective of dogma, which creates its own terrible outcomes.

But let's talk about domain-driven development. Without getting too bogged down into the details of the approach, the idea is pretty straightforward: describe you domain model without reference to any lower-level concerns, so you can effectively write your domain logic in an abstract language tuned to your specific needs. In other words, it's just a pretty good practice. DDD offers tools and techniques for doing it, and as stated, can be adopted as a point of dogma instead of technique.

Julien joined a team which bragged about their use of DDD. Everything they did followed DDD best practices, they said. The fact that they piled up all sorts of related buzzwords when talking about it should have been a red flag.

Here's one of their "domain" classes:

namespace Acme\Documents\Domain; interface CakeSessionRepositoryInterface { public function isLoggedIn(string $cookieId); }

In "domain" patterns, a "repository" interacts with domain objects in your data store. Things it shouldn't do:

  • perform an authentication check
  • interact with cookies
  • care about session information
  • be tightly coupled with your underlying web framework (CakePHP, in this case)

Excluding the curly-brackets, every line in this short snippet is wrong, which is impressive.

It looks like their domain shouldn't drink and drive.

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Remy Porter