Donut Lab’s solid-state battery could barely hold a charge after getting damaged | The VergeSkip to main contentThe homepageThe VergeThe Verge logo.The VergeThe Verge logo.TechReviewsScienceEntertainmentAIPolicyHamburger Navigation ButtonThe homepageThe VergeThe Verge logo.Hamburger Navigation ButtonNavigation DrawerThe VergeThe Verge logo.Login / Sign UpcloseCloseSearchTechExpandAmazonAppleFacebookGoogleMicrosoftSamsungBusinessSee all techReviewsExpandSmart Home ReviewsPhone ReviewsTablet ReviewsHeadphone ReviewsSee all reviewsScienceExpandSpaceEnergyEnvironmentHealthSee all scienceEntertainmentExpandTV ShowsMoviesAudioSee all entertainmentAIExpandOpenAIAnthropicSee all AIPolicyExpandAntitrustPoliticsLawSecuritySee all policyGadgetsExpandLaptopsPhonesTVsHeadphonesSpeakersWearablesSee all gadgetsVerge ShoppingExpandBuying GuidesDealsGift GuidesSee all shoppingGamingExpandXboxPlayStationNintendoSee all gamingStreamingExpandDisneyHBONetflixYouTubeCreatorsSee all streamingTransportationExpandElectric CarsAutonomous CarsRide-sharingScootersSee all transportationFeaturesVerge VideoExpandTikTokYouTubeInstagramPodcastsExpandDecoderThe VergecastVersion HistoryNewslettersArchivesStoreVerge Product UpdatesSubscribeFacebookThreadsInstagramYoutubeRSSThe VergeThe Verge logo.Donut Lab’s solid-state battery could barely hold a charge after getting damagedComments DrawerCommentsLoading commentsGetting the conversation ready...TransportationCloseTransportationPosts from this topic will be added to your daily email digest and your homepage feed.FollowFollowSee All TransportationNewsCloseNewsPosts from this topic will be added to your daily email digest and your homepage feed.FollowFollowSee All NewsScienceCloseSciencePosts from this topic will be added to your daily email digest and your homepage feed.FollowFollowSee All ScienceDonut Lab’s solid-state battery could barely hold a charge after getting damagedBut on the other hand, it didn’t burst into flames.But on the other hand, it didn’t burst into flames.by Andrew J. HawkinsCloseAndrew J. HawkinsTransportation editorPosts from this author will be added to your daily email digest and your homepage feed.FollowFollowSee All by Andrew J. HawkinsMar 23, 2026, 5:35 PM UTCLinkShareGiftImage: Tim StevensAndrew J. HawkinsCloseAndrew J. HawkinsPosts from this author will be added to your daily email digest and your homepage feed.FollowFollowSee All by Andrew J. Hawkins is transportation editor with 10+ years of experience who covers EVs, public transportation, and aviation. His work has appeared in The New York Daily News and City & State.Donut Lab is on a mission to prove to the world its solid-state battery is real, one independent test at a time. We’ve seen speed charging tests, extreme heat tests, and not-a-supercapacitor tests. Today’s test is to see how the battery holds up under damage. The results: While it could barely sustain a charge, it didn’t burst into flames, which Donut Lab sees as a victory.If you’ll recall, during the extreme heat tests, the pouch surrounding Donut’s battery lost its vacuum seal. This led to researchers at Finland’s state-owned VTT Technical Research Centre, which conducted all of the lab’s previous tests, to explore whether the cell could still function under these high-stress, high-temperature conditions. As Donut notes, damage such as what was sustained by its pack during the heat test has been known to cause fire or thermal runaway in conventional lithium-ion batteries. The startup wanted to see whether its solid-state battery could avoid a similar calamity.Researchers conducted three tests: a baseline test of five cycles at 1C (26 amps); a high-stress test of 50 cycles at 5C (130 amps); and another final baseline test of five cycles at 1C to measure degradation. After the tests, the team observed a sharp drop in energy capacity, from 24.7 amp-hours to 11.2 Ah, or a loss of approximately 55 percent. They also recorded a drop in efficiency from 89.6 percent to 83 percent, and noted a 17 percent increase in the pack’s thickness.Given the damage sustained by the pack, the results shouldn’t be that surprising. The loss of the vacuum seal certainly accelerated the battery’s degradation and contributed to its thick, swollen state after the test. Still, Donut Lab said this was further proof that its battery can avoid some of the worst outcomes of a damaged lithium-ion battery.“No temperature spikes, no fire risk,” the company said on its IDonutBelieve.com site. “In this scenario the Donut Battery fails gracefully when damaged, continuing to operate safely at reduced capacity rather than posing danger to the user.”But the tests also represent the closest that Donut Lab’s battery has come to a cycle test — and it was under these damaged conditions. The startup has yet to demonstrate how its pack holds up under an accelerated aging procedure that repeatedly charges and discharges the cells to evaluate their long-term performance and safety. Donut has previously claimed its solid-state battery can last 100,000 cycles, which would represent approximately 270 years of charging and discharging. This would be orders of magnitude greater than the 1,000-2,000 full charging and discharging cycles that the average EV battery can withstand before its capacity starts to degrade.And more importantly, Donut has yet to ask for an independent verification for its claimed 400 watt-hours per kilogram of energy density. That seems like a simple enough test — all you have to do is weigh the cell and measure its output — and it’s unclear why Donut Lab hasn’t asked for it yet.We’ll have more to say about Donut Lab’s tests and what independent experts are saying about the startup in the weeks to come.Follow topics and authors from this story to see more like this in your personalized homepage feed and to receive email updates.Andrew J. HawkinsCloseAndrew J. HawkinsTransportation editorPosts from this author will be added to your daily email digest and your homepage feed.FollowFollowSee All by Andrew J. 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Donut Lab, a startup focused on developing solid-state battery technology, conducted a series of tests examining the performance of its battery under conditions mimicking typical damage scenarios. As reported by Andrew J. Hawkins, the experiments were initially intended to assess the battery’s response to thermal stress following previous, more extreme heat tests where the battery’s containment pouch experienced a vacuum seal failure. The tests involved three distinct phases: a baseline cycle at 1C (26 amps), an elevated stress test at 5C (130 amps), and a final baseline cycle at 1C to evaluate degradation. Following these tests, a significant capacity decline was observed, decreasing from an initial 24.7 amp-hours to 11.2 amp-hours – representing a 55 percent loss. Furthermore, efficiency dropped from 89.6 percent to 83 percent, accompanied by a noticeable 17 percent increase in pack thickness.

The results, while not entirely unexpected given the damage sustained to the battery’s packaging, highlighted the core objective of the research: to determine whether Donut Lab’s solid-state battery could mitigate the risks associated with traditional lithium-ion battery failures, specifically thermal runaway. Crucially, the battery did not ignite or experience any temperature spikes during the damage simulation, a factor that Donut Lab considers a significant achievement. According to the company’s website, IDonutBelieve.com, this “graceful failure” demonstrated the battery’s ability to operate safely at reduced capacity rather than posing a danger.

However, the tests also revealed areas for potential improvement and highlighted some outstanding questions. The degradation observed – roughly 55% – suggests a substantial rate of performance decline under stress. Moreover, the startup’s claims regarding a projected 100,000-cycle lifespan, equating to roughly 270 years of charge/discharge cycles, remain unverified. Donut Lab has yet to pursue independent verification of its 400 watt-hours per kilogram energy density claim. This testing approach, which involved simply weighing and measuring output, appears somewhat cursory, and the lack of independent confirmation raises concerns regarding the accuracy of the claimed performance metrics, particularly given the significant degradation observed.

The experiments represent the closest Donut Lab’s battery has come to a formal accelerated aging procedure – a critical step in demonstrating long-term viability. The limited nature of the damage simulation, coupled with the lack of independent verification, underscores the need for more robust testing protocols. Hawkins noted that the success in avoiding a catastrophic event is a notable aspect, but the battery's performance under sustained, demanding conditions still requires comprehensive scrutiny. The work remains preliminary, and further investigation, particularly in the realm of independent validation, is imperative to substantiate Donut Lab’s ambitious claims regarding its solid-state battery’s potential to revolutionize energy storage.