Finnish startup Donut Lab has faced plenty of skepticism since announcing its “miracle” solid-state battery earlier this year. Today, the company answered doubts with hard data — and the results are impressive.
The first independent test, conducted by VTT Technical Research Centre of Finland, confirms that Donut Labs solid-state battery can charge significantly faster than traditional lithium-ion packs. In testing, the battery achieved 0-80% charge in just 4.5 minutes while retaining 99% of its capacity. In more conservative tests with better cooling, it hit 80% in about 9.5 minutes while keeping 100% of its capacity.
Why This Matters
Currently, most EV batteries charge at 1C to 3C rates, meaning a 30-40 minute charging session is standard. Donut Labs battery reached 11C charging rates — a massive leap that could transform EV charging from a half-hour wait to a 5-minute pit stop.
“This could make EV charging feel like refueling at a gas station,” noted The Verge.
No Cooling Required
Perhaps most surprising: VTT tested the battery with minimal cooling — just passive aluminum plates, no active liquid cooling systems. Traditional batteries need complex thermal management to charge safely at high speeds. Donut Labs design apparently sidesteps this entirely.
Claims Still Unverified
While charging speed is now confirmed, some key questions remain:
Energy density: Donut claims 400 Wh/kg (vs. 200-300 Wh/kg for lithium-ion), but VTT didnt verify this
Cycle life: The company claims 100,000 cycles; traditional batteries last 1,500-3,000
Dendrite issue: Future tests need to address microscopic short-circuit risks
Donut Lab plans more independent test results as part of its “I Donut Believe” series.