One of the splashiest claims in the announcement was that cells would have an energy density of 400 watt-hours per kilogram (the top commercial lithium-ion batteries today sit at about 250 to 300 Wh/kg). It was also claimed that the cells could charge in as little as five minutes, last 100,000 cycles, and retain 99% of capacity at high and low temperatures—while costing less than lithium-ion cells and being made from “100% green and abundant materials with global availability.”

They've begun to publish third part testing.

I posted about Donut Lab before. Their parent company makes EV super bikes and Donut Lab does their R&D and resells it. Afaik they don't have a history of making sensational claims, but a chemical engineering breakthrough of this magnitude does seem unlikely.

A friend of mine is a battery physicist at a flying car company, and is also world class at being skeptical, so perhaps once they release more evidence I'll reach out and ask what he thinks.