Donut Lab's 'Solid-State' Battery Exposed As Regular Li-Ion (electrek.co)
(Wednesday June 10, 2026 @11:00AM (BeauHD)
from the would-you-look-at-that dept.)
A [1]battery researcher's investigation , backed by more than 20 independent experts, claims Donut Lab's much-hyped "solid-state" battery is [2]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.
[1] https://www.youtube.com/watch?v=j5oyVNjrUPI
[2] https://electrek.co/2026/06/08/donut-lab-solid-state-battery-exposed-lithium-ion-fraud/
> 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.
[1] https://www.youtube.com/watch?v=j5oyVNjrUPI
[2] https://electrek.co/2026/06/08/donut-lab-solid-state-battery-exposed-lithium-ion-fraud/