DonutLab Unveils “Solid-State Battery” at CES: Claims 400Wh/kg, 5-Minute Fast Charge—Industry Skeptical

At CES, Finnish startup DonutLab made a high-profile showcase of its so-called "solid-state battery" technology, claiming an energy density of 400 Wh/kg, a full charge in just five minutes, a cycle life of up to 100,000 cycles, a theoretical lifespan exceeding 800 years, and normal operation at temperatures as low as -30°C. Founder Marko Lehtimäki stated the technology is ready for mass production, with initial plans to build a 1 GWh production facility in Finland and potentially expand to the U.S. in the future. However, industry experts remain highly skeptical, noting that the claimed specifications far exceed current technological capabilities and that the company has not disclosed any patents or peer-reviewed papers to substantiate its claims. Some experts speculate the product might actually be a supercapacitor—typically offering only around 50 Wh/kg in energy density. Additionally, with just 22 employees, DonutLab’s ability to achieve mass production has also been called into question.