Donut Lab's Solid-State Battery: A Breakthrough in Fast Charging?

Finnish startup Donut Lab has recently released independent test results for its solid-state battery, conducted by the VTT Technical Research Centre of Finland. The tests confirm that the battery can charge from 0 to 80 percent in approximately 4.5 minutes at an extreme charging rate of 11C, with a full charge taking just over 7 minutes. This performance significantly outpaces traditional lithium-ion batteries, which typically charge at rates of 1C to 3C with active cooling systems.

Official: Donut Labs’ solid-state EV battery fully charges in seven minutesThe VergeElectrek

The VTT tests evaluated the battery's charging speed and thermal behavior under two configurations: one with two aluminum cooling plates and another with a single plate. The results showed that the battery could maintain nearly 100 percent of its capacity even after rapid charging, suggesting a potential transformation in electric vehicle (EV) charging times.

The Verge

Donut Lab's solid-state battery reportedly delivers an energy density of 400 watt-hours per kilogram (Wh/kg), which is higher than most current lithium-ion batteries that range from 200 to 300 Wh/kg. The battery is also claimed to last up to 100,000 cycles, a figure that far exceeds the typical lifespan of 1,500 to 3,000 cycles for conventional batteries. The tested battery has a capacity of 26 amp-hours (Ah) and nominal energy of 94 watt-hours (Wh).

The Verge

However, the tests revealed that at the highest charging rates, the battery's temperature reached a critical 90°C, necessitating a shutdown to prevent damage. This incident raises questions about the battery's thermal management capabilities, as Donut Lab has marketed it as requiring no active cooling.

The Verge

Despite the promising results regarding charging speed, several key claims made by Donut Lab remain unverified. Critics have pointed out that the VTT report does not confirm the battery's chemistry or address the "dendrite issue," which can lead to electrical shorts in solid-state batteries. Additionally, the report does not validate the battery's claimed energy density or cycle life, which some experts have labeled as "physically impossible."

The Verge

Industry skepticism has been fueled by comments from figures such as Svolt Energy's chairman, who described Donut Lab's claims as contradictory. Donut Lab's CEO, Marko Lehtimäki, has defended the technology, asserting that it will be implemented in Verge Motorcycles by Q1 2026.

Electrek

Donut Lab has announced that further independent tests will be conducted as part of its "I Donut Believe" series, aiming to address the unanswered questions surrounding its solid-state battery. While the initial results are a step forward, the company faces the challenge of substantiating its more extraordinary claims regarding energy density and cycle life.

Electrek

• “Unlike other solid-state batteries requiring high compressive pressures and undergoing volume changes of up to 15-20 per cent during recharging cycles, the Donut Battery does not require special compression or more extensive cooling,” — Ville Piippo, CTO of Donut Lab

Official: Donut Labs’ solid-state EV battery fully charges in seven minutes

• “Electrek’s Take We’ve been tracking the Donut Lab story since Verge first announced its solid-state motorcycle at CES, and we’ve maintained that extraordinary claims require extraordinary proof.” — Electrek’s commentary on the testing results.

Electrek