Donut Lab claims solid-state batteries will enter production this year, but experts are sceptical

Startup says batteries will enter production this year, but experts doubt some claimed specifications

Finnish start-up Donut Lab has announced what it calls a breakthrough in solid-state batteries - often described as the “holy grail” of battery technology because of their high energy density, long service life and potential for rapid charging. Donut Lab, a spin-off from Verge Motorcycles, says its batteries will move into production later this year.

Claimed performance of Donut Lab solid-state batteries

Some specialists remain unconvinced, largely because the company lacks a well-known research track record and has not published scientific data in the open literature. Even so, Donut Lab has released results from independent testing carried out by Finland’s leading state research and technology organisation, VTT Technical Research Centre of Finland.

According to those tests, the batteries meet the company’s headline figures: an energy density of 400 Wh/kg, charging in 5 minutes, a lifespan of up to 100,000 cycles, and operation across temperatures from -30 to 100 °C. Donut Lab also says the batteries contain no rare-earth elements and avoid flammable liquid electrolytes.

What remains unproven and reliability concerns

Despite the published test summary, key details - including the chemistry, density claims and longevity under real-world conditions - are still viewed as unproven by critics. During thermal testing of Donut Lab’s batteries, issues were reported with vacuum sealing integrity, raising questions about the robustness of the approach.

Researchers and other experts also point out a known obstacle for solid-state batteries: dendrite formation - metallic structures that can grow, crack through materials and ultimately cause a short circuit.

Rapid progress in China on solid-state batteries

While Donut Lab works to address the shortcomings, development elsewhere is accelerating, particularly in China. CATL has recently filed a patent for batteries with an energy density of 500 Wh/kg and says it plans to begin small-scale production in 2027. Other Chinese manufacturers, including FAW, have likewise stated that their batteries are ready for integration into electric vehicles.

Donut Lab’s message to the market and next iteration

Donut Lab argues that “their technology is a threat to major market players”. The company’s chief executive, Marko Lehtimäki, has said resistance from the industry will only strengthen, despite the evidence.

The firm has also announced a second version of the battery that it describes as more production-ready, with deliveries to customers scheduled for the end of the year.