Some earlier background from 2014 about a breakthrough in the development of better and cheaper Batteries.
Novel Sodium-Conducting Material Could Improve Rechargeable Batteries
They do not address the issue of battery weight, but how heavy can powdered compounds be?
Here are the latest research developments shared on April 1st. Only a very serious entity can release information on that date, and be taken seriously. I think the National Institute of Standards and Technology (NIST) is one of those entities.
For Rechargeable Batteries That Crush the Competition, Crush This Material
I don’t see this technology on a summit before this decade is out, but some day.