[Animats]

It's nice that they have what they claim is a solid state battery. But having a small prototype isn't that big a deal at this point. All the major players have prototype solid state batteries that work. Nobody has volume production yet, and volume production seems to be hard and expensive, according to CATL and Samsung.

Mercedes has a test car with a solid state battery.[1] The battery is from Factorial Energy. There's only one such car, and they don't say how much it cost to make the prototype battery.

Ducati has a test motorcycle with a solid state battery.[2] The battery is from QuantumScape. There's only one such motorcycle.

Here's Fraunhofer IKTS making a solid state battery at lab scale.[3] The whole process is shown. Huge amount of effort to make one coin cell.

Samsung prototype.[4] Samsung has been talking about shipping tiny solid state batteries for wearables in 2026. Still too expensive for cell phones, which gives a sense of cost.

All the serious players can make a prototype by now. But the chemistry that's used for the prototypes may not be suitable for production. They have to balance capacity, weight, charge time, cycle life, manufacturing cost, and materials cost. (Samsung made a battery with a substantial silver content. It works, but that's not going to be a volume product)

These problems will be overcome, because throwing money at them works. The history of the tungsten-filament light bulb is worth reviewing. Making fine tungsten wire is very difficult. From 1913 to 2010, a huge plant in Euclid, Ohio, made most of the tungsten wire for light bulbs. There were a lot of process steps.[5]

[1] https://electrek.co/2025/02/24/mercedes-tests-first-solid-st...

[2] https://www.ducati.com/ww/en/news/ducati-s-electric-research...

[3] https://www.youtube.com/watch?v=j5SVrp8N-1M

[4] https://news.samsungsdi.com/global/articleView?seq=203

[5] https://www.youtube.com/watch?v=ZuhapGSexyg

[Tuna-Fish]

Precisely. People are questioning the wrong things, I find it really easy to believe that Donut has a 400Wh/kg battery that can do 11C charging. Because that's something that can be easily externally verified, and they are sending that battery out to testers, and also because the existence of such a battery isn't new or shocking, many labs have prototypes in roughly the same performance envelope.

But that doesn't mean they have a winner, if the battery was ridiculously expensive to make. Their claims about cost are much more suspicious, and they have shown no proof about them.