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.
