I just got out of a webinar about their battery efforts in which they claimed patents for:
graphene coated silicon with pores for ions and internal expansion space
elastic polymer coated silicon (see Tesla Battery Day)
I'm waiting for a web link to the webinar with the slide deck but I have a little skepticism. They claimed patents and even referenced a slide from Tesla Battery Day. But I'm not having a lot of luck finding any evidence of even prototype production. The term "patent sitter" comes to mind.
