Finnish startup Donut Lab has released test data to verify its solid-state battery technology and rapid charging capabilities [1].

The results are intended to silence critics who questioned if the technology is a functional battery or merely a supercapacitor. If verified, the ability to charge an electric vehicle in minutes would remove a primary barrier to mass EV adoption.

Donut Lab said its battery achieves an energy density of 400 Wh/kg [1] and can be charged in five minutes [1]. To support these figures, the company provided data from 60 charge cycles and verification from an independent lab [2].

In a separate test aimed at proving the technology is a real battery, Donut Lab said its battery retained 97.7% [3] of its charge after 10 days [3]. The company worked with spin-off partner Verge to develop and test these prototypes.

Despite the new data, the company faces significant opposition. Dr. Ben Miles said Donut Labs has made bold claims about its technology [1]. More severe allegations surfaced via Electrek, where a former employee of a supplier said the miracle battery is a fraud [4].

Donut Lab has denied these allegations. The company continues to release data to demonstrate the viability of its solid-state cells, which are designed to replace the liquid electrolytes found in traditional lithium-ion batteries, a change that typically increases safety and energy capacity.

“Donut Lab reported that its battery achieves an energy density of 400 Wh/kg”

The conflict between Donut Lab's technical data and the allegations from a former supplier employee highlights the high-stakes nature of the solid-state battery race. While the 60-cycle test and independent verification provide a baseline of evidence, the industry remains skeptical of 'miracle' claims until large-scale, third-party transparent auditing is completed. The outcome will determine if Donut Lab is a genuine innovator or another failed promise in the energy sector.