This battery was already mentioned in this thread, but there was no talk about energy density. Looks like they've since provided a little chart. So if you have typical 44g 18650 cell, according to this chart, that's about 4400mAh.
https://www.youtube.com/watch?v=OJwZ9uEpJOo
http://powerjapanplus.com/battery/equation/
They're making some bold claims. Let's hope it sees the light of day.
https://www.youtube.com/watch?v=OJwZ9uEpJOo
http://powerjapanplus.com/battery/equation/

They're making some bold claims. Let's hope it sees the light of day.