After weeks of industry skepticism and accusations that its technology was technically impossible, Finland-based Donut Lab has released independent test results from the VTT Technical Research Centre of Finland validating its revolutionary solid-state battery claims. The results demonstrate ultra-fast charging capabilities without requiring active cooling systems or extreme pressure.
VTT conducted tests under what engineers described as worst-case scenarios, without active temperature controls and allowing the cell’s heat to rise freely at high charging rates. Using C-rates as a measurement standard, where 1C equals a one-hour charge, researchers tested the battery at 5C (roughly 12-minute full charge equivalent) and 11C (approximately 5-6 minute equivalent).
At the 5C rate, the battery reached 80% state of charge in approximately 9.5 minutes and full capacity in just over 12 minutes. Most significantly, at the extreme 11C rate, the battery achieved 80% charge in just 4.5 minutes and full capacity in just over 7 minutes, validating the company’s earlier claims of five-minute charging.
After rapid charging, the cell retained between 98.4% and 99.6% of stored energy, demonstrating the battery’s ability to handle intense power input with minimal losses, a remarkable achievement that addresses one of the most significant challenges in battery technology.
Unlike many solid-state battery concepts in development, Donut Lab’s design accomplished these results without requiring active cooling systems, unusual pressure, or compressive force on the cell. This simplicity represents a significant departure from traditional lithium-ion batteries that require elaborate cooling and structural support, adding weight and cost to electric vehicle battery packs.
Donut Lab CTO Ville Piippo highlighted the structural advantages, noting that the design’s simplicity could reduce complexity in EV battery packs significantly. The passive cooling approach may help manufacturers fundamentally rethink how to build future electric vehicle batteries, as traditional systems often require extensive thermal management infrastructure.
The independent validation arrives after significant industry criticism, with major battery experts publicly calling Donut Lab’s claims a “scam” and asserting the technology was technically impossible. The VTT testing, conducted without active thermal management or special conditions, effectively rebuts these accusations.
While the tests examined only individual cells rather than complete battery packs, the results provide strong evidence the technology could scale beyond laboratory conditions. Donut Lab’s approach without requiring novel cooling or pressure systems suggests faster integration into commercial products. The validation could shift industry conversations, particularly among EV manufacturers seeking faster charging and higher energy density solutions.
However, mainstream adoption of solid-state batteries remains years away for most automakers, with Donut Lab’s independent test results potentially accelerating timelines for companies exploring rapid-charging technology for future electric vehicles.
