A detailed investigation confirms Donut Lab's 'solid-state' battery is actually a lithium-ion cell, with over 20 experts and electrochemical data proving the claims were false.
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Donut Lab’s ‘solid-state’ battery exposed as regular li-ion in damning investigation
Fred Lambert| Jun 8 2026 - 12:18 pm PT
A comprehensive investigation by battery researcher Ziroth, involving over 20 independent battery experts, has produced what amounts to definitive proof that Donut Lab’s “miracle” solid-state battery is actually a lithium-ion cell. The company raised approximately $25 million from over 1,300 mostly small investors based on claims that now appear to be false.
The investigation traces the battery technology back to a German company called CT Coatings, reveals a web of companies hiding behind aggressive NDAs, and presents electrochemical evidence — including voltage curves and cell expansion data — that conclusively identifies the tested cell as lithium-ion, not the revolutionary sodium-ion solid-state chemistry Donut Lab promised.
From skepticism to confirmation
We have been covering Donut Lab’s claims with skepticism since the company
shocked the battery world at CES 2026 with claims of a 400 Wh/kg, 100,000-cycle, 5-minute-charging solid-state battery. In January, I
interviewed CEO Marko Lehtimäki and told him directly that he was either going to lose all his credibility or revolutionize the world. It looks like it was the former.
At the time, the incentives to lie weren’t clear to me, and the short timeline to delivery gave the claims some credibility. But as we tracked the
independent testing results, the red flags kept piling up. Five tests from VTT and not a single one addressed the two claims that actually mattered: the 400 Wh/kg energy density and the 100,000-cycle life. Then came the
whistleblower complaint from Nordic Nano’s former CCO, alleging the battery specs were never achieved.
Now, Ziroth’s investigation fills in the gaps with hard electrochemical evidence.
The evidence: voltage curves and cell expansion prove lithium-ion
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 Seinäjoki 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 web of companies behind the fraud
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.
The relationship works like this: CT Coatings was the technology provider, Nordic Nano was supposed to be the manufacturer, and Donut Lab was the commercializer. Nordic Nano has reportedly never manufactured a single battery cell.
Julian Zanau from Fraunhofer described meeting with CT Coatings representatives and being unimpressed: “The first impression I got was that these people have no idea how a battery actually works. They were talking about no rare earth metals in their batteries and therefore no lithium, and to any chemist lithium has nothing to do with rare earth minerals.”
Meanwhile, Donut Lab performed its own technical due diligence instead of getting independent validation — an approach that former Nordic Nano CCO Lauri Peltola described as deeply inadequate given that neither company had battery chemistry expertise.
Verge ‘production vehicle’ claim was verifiably false
Beyond the chemistry, the investigation documents clear-cut lies. Donut Lab claimed to have a production vehicle shipped to consumers in Q1 2026. On the last day of the quarter, they announced the “first production motorcycle” off the line.
But an internal video to reservation holders told a different story: the first bikes would be for Verge’s internal fleet, with the purpose of refining the manufacturing process before shipping to customers. That is, by definition, a pre-production vehicle.
In an interview with Finnish media, Lehtimäki then admitted that the 400 Wh/kg cells were not in the bikes and that the cell tested by VTT “is not even the cell that’s going to be shipped to customers.” Leaked emails showed Donut Lab asking CT Coatings when they would actually receive proof of the claimed specs. Apparently, no proof was ever provided.
$25 million raised from 1,300+ small investors
The most troubling aspect of the investigation centers on how the money was raised. Donut Lab has over 1,300 shareholders, with over 900 holding 50 or fewer shares — likely representing investments between $3,000 and $23,000 per person. Many came from a crowdfunding exercise on Finland’s Springvest platform in 2023 for Verge Motorcycles.
When Verge was restructured and Donut Lab was spun out, the company’s valuation jumped from a struggling motorcycle company to a parent company of a “half a billion euro portfolio” — all because of the miracle battery. An investor letter from Lehtimäki promised “a potential return on investment of up to 10x in just 12 to 18 months” and urged investors that “it is not yet too late to invest more.”
The investigation argues that this approach — using self-validated due diligence to raise money from investors who lacked the means to scrutinize the technology — was chosen deliberately to avoid the kind of technical scrutiny that venture capital firms would demand.
The valuation was later inflated to $1.25 billion after the CES presentation. Finnish financial authorities and criminal authorities are reportedly investigating.
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