Sodium-sulfur batteries are already in use for grid storage [0] [1]. They're large and they have to be kept hot, so they won't work for mobile applications. This article seems to be describing one that works at room temperature.

[0] https://www.energy-storage.news/uae-integrates-648mwh-of-sod...

[1] https://www.bestmag.co.uk/worlds-largest-sodium-sulphur-ess-...