Comment by sylario

This summer a French company started to sell sodium ion battery power tool in a major hardware store.

National French research agency announcement: https://www.cnrs.fr/fr/cnrsinfo/batteries-sodium-ion-une-pre...

The power tool : https://www.leroymerlin.fr/produits/outillage/outillage-elec...

Unfortunately, all I could found about the Wh/kg efficiency was an article about the same company saying they were currently able to build cells at 90Wh/Kg in 2017.

Nevertheless, it's not a promise, it's a product currently on sale.