what the heck happened to potassium ion batteries?

Back in 07 a company called starsway said they had PMP powered by them but its the only reference i've seen since and the company never mentioned it again. Seems like there would be a bit more interest as potassium is cheaper and they supposedly last millions of cycles.

You guess is a good as mine. Chances are there was some problem in manufacturing the device at a competitive price.

I'd say a competitor bought them out and shelved the process....