At CES 2026, a relatively unknown startup called Donut Lab made a claim that sent shockwaves and skepticism through the EV industry. The company unveiled what it claimed to be the world’s first production-ready solid-state battery, boasting specifications that read like a sci-fi wish list: 400Wh/kg of energy density, a lifespan of 100,000 cycles, and the ability to charge from 0-80% in under five minutes.
When industry experts cried foul, Donut Lab responded by launching their “I Donut Believe” campaign, alongside the publication of independent test results from the highly respected VTT Technical Research Centre of Finland to prove their breakthrough was the real deal.
But a deeper dive into the actual VTT report reveals that while Donut Lab has undoubtedly built something capable of absorbing massive electrical current, the holy grail of solid-state batteries may still be a long way off.
The VTT Report: What Was Actually Tested?
It is important to understand how third-party testing labs operate. VTT is a state-owned, world-class research institution. If they publish a number, that number is accurate. However, they are a testing facility - not an auditing firm. They only run specific, isolated tests that the client (Donut Lab) pays them to execute.
Here is how Donut Lab’s marketing claims stack up after reviewing the actual VTT test data provided in the report.
The first claim, for fast charging, is verified by the VTT report, which confirms that a 26 Ah Donut cell successfully charged from 0% to 80% in just 4.5 minutes at an extreme 11C charge rate.
The second claim, for weight density, is unverified. Perhaps the single biggest selling point of this battery is the 400 Wh/kg claim, which is roughly double the energy density of standard lithium-ion. Yet, the VTT report completely omits the cell’s weight and physical dimensions. Without knowing the physical information, verifying its energy density is impossible.
Finally, the last of Donut’s claims is the 100,000-cycle lifespan, which was also not tested by VTT. The report covers only a handful of fast-charge cycles, well before any degradation would set in.
Thermal Red Flag
While the fast-charging data is real and genuinely impressive, the testing methodology raises some questions about real-world automotive viability.
During the 11C fast-charging test, the battery cell was placed between massive aluminum heat sinks to passively manage temperatures. Even with this sizeable thermal mass, the cell’s surface temperature spiked to 63°C. In a separate test using only a single heat sink, the cell hit 90°C, and the test had to be temporarily aborted to let the battery cool down.
Industry observers have calculated that scaling the specific ratio of passive thermal mass to a full-size EV pack would require thousands of pounds of heat sinks - or equivalent heat dumping from an active management system. Donut Lab markets the battery as needing no active cooling, but the test data clearly show that pushing the battery to its marketed charging speeds generates immense, potentially unmanageable heat.
Manufacturability At Scale
Building a single, high-performing pouch cell in a controlled lab is entirely different from manufacturing millions of them consistently and cheaply.
Currently, Donut Lab’s primary real-world application is through a partnership with Verge Motorcycles, a premium EV bike manufacturer. Integrating a few cells into a high-end, low-volume motorcycle is a fantastic proof of concept, but it is leaps and bounds away from revolutionizing the EV world.
Despite promises of Q1 2026 deliveries for new bikes, Verge’s CEO and website have confirmed that volume customer deliveries will likely stretch late into the year or even into 2027 as they navigate supply chains and regulatory approvals.
If this cell is actually what it appears to be, we’re on the verge of a massive revolution in the EV and handheld device markets. Ultimately, until independent auditors are allowed to weigh and test a production-intent cell from Donut Lab, we’ll continue taking their “I Donut Believe” campaign quite literally.
