The company paid independent testing organization VTT to do limited tests for battery. The VTT.fi did just the test it was paid to do, nothing more.
The result: Donut battery behaves just like any other battery is expected to behave in same testing. For example, you can fast charge normal lithium ion battery at Donut speeds 4 times.
Founders behind Donut have new AI startup Asilab, marketed with similar bullshit "This changes everything" story. It seems that they are just hustlers separating dumb investors from their money.