The announcement electrified the industry and attracted significant investment, but it also drew immediate skepticism. The chairman of Chinese battery giant Svolt publicly labeled it a “scam,” noting the claimed parameters were contradictory and defied basic technical knowledge .
The most conclusive evidence came from a comprehensive investigation led by PhD researcher and YouTuber Ziroth, published on June 8, 2026. Ziroth assembled a team of over 20 independent battery experts, including researchers from the Fraunhofer Institute and several universities, to perform a forensic analysis .
Their electrochemical testing was definitive. The cell's voltage curve, which stabilized at 3.7 to 3.8 volts at a 50% state of charge, matched the signature of a high-nickel, nickel-cobalt-manganese (NCM) lithium-ion battery. This was fundamentally incompatible with the characteristics of a sodium-ion or a genuine solid-state cell . The investigation traced the actual technology back to a German company, CT Coatings, revealing that Donut Lab had effectively rebranded existing lithium-ion cells as its own breakthrough . A complex web of non-disclosure agreements (NDAs) between Donut Lab, CT Coatings, and the Finnish manufacturer Nordic Nano had obscured the true supply chain . Donut Lab’s CEO, Marko Lehtimäki, simultaneously held a board seat at Nordic Nano, deepening the corporate entanglement .
Even before Ziroth’s investigation was published, the narrative had begun to crumble from the inside. In April 2026, Lauri Peltola, the Chief Commercial Officer and a founding shareholder of Nordic Nano, filed a criminal whistleblower complaint with Finnish police against Donut Lab .
Peltola’s complaint made three core allegations :
Peltola didn’t just go to the police; he also filed complaints with Finland’s financial supervisory authority and the Chancellor of Justice, and leaked confidential company documents to the press, including the prominent Finnish newspaper Helsingin Sanomat . Donut Lab and Nordic Nano denied wrongdoing, claiming Peltola lacked a complete understanding of the technology, but the internal communications he provided gave his testimony substantial weight .
Amid the mounting doubt, Donut Lab sought to regain credibility by commissioning five independent tests from Finland’s state-backed VTT Technical Research Centre. The results, released between February and March 2026, confirmed some peripheral capabilities but strategically evaded the most extraordinary claims .
The five tests validated select secondary claims:
Crucially, no VTT report tested or verified the headline specifications of 400 Wh/kg energy density or 100,000-cycle life. The energy density test would have simply required weighing the cell, a conspicuously absent data point . VTT’s findings, while real, were a masterclass in selective transparency—proving the battery could charge fast and withstand heat, while dodging the two core metrics that had defined its “miracle” status .
Based on the now-debunked narrative, Donut Lab raised approximately $25 million from over 1,300 investors, predominantly small retail backers who bought into the vision of a clean-energy revolution . The fallout has left a trail of unanswered questions that carry significant legal and financial implications: