JAC Motors, a Volkswagen-backed Chinese automaker, unveiled the first mass-produced EV with a sodium-ion battery through its new Yiwei brand. Although sodium-ion battery tech has a lower density than lithium-ion, its lower costs, simpler and more abundant supplies and superior cold-weather performance could help accelerate mass EV adoption.
You can buy them right now, there’s more links in the 18650masterrace subreddit, but here’s just one:
https://srikobatteries.com/product/sodium-ion-18650-1250mah-50a-rechargeable-battery/
However good luck finding a BMS that works for it’s particular voltage range, don’t think AliExpress has any yet.
I haven’t seen any posts from those diy type folks experimenting with them yet. Sodium ion cells just became available within the last few months or so.