Are you referring to Professor Sadoway? I greatly enjoyed his Solid State Chemistry course! Always wondered what will come of his flow battery company (Ambri). Looks like they are still steadily making progress, no?
I will say though, Sadoway is a bona fide friggin genius. I'm still not anywhere close to sold on flow batteries or molten salt/metal batteries, but Sadoway's work is brilliant. He had me genuinely convinced we were about to make all of our steel electrolytically. I still really hope we end up that way.