It’s about thermal storage, you don’t use table/sea salt for that, and you don’t need a lot of salt, because the salt is in a closed loop; it’s not being consumed.
If you read the article you sent me, you'll learn that, just as I said, you don't use sodium chloride, aka table salt, aka sea salt, for these purposes.
A better example are sodium ion batteries, which are about to take off in a big way