They tend to be large utility scale things that look like a chemical plant, correction, are a chemical plant with electrical storage as the product.
Liquid electrolyte batteries have been a thing from when batteries have been invented. But not much work has been done to really scale it up.
A huge redox-flow battery is currently under construction in Switzerland https://www.swissinfo.ch/eng/climate-solutions/switzerland-b...
The 'Just Have a Think' channel did a video on the Swiss battery here - https://www.youtube.com/watch?v=CPAFeTvjVzY
https://ec.europa.eu/food/food-feed-portal/screen/food-addit...
Potassium ferrocyanide: 1.6g/kg LD50 Potassium cyanide: 5mg/kg
So cyanide is approx 320 times more toxic.
Good luck selling batteries full of some variant of cyanide to general public, i can almost imagine it working till people hear that keyword.
You can have safe battery chemistry or useful battery chemistry. (Not an expert, open to correction.)
Or perhaps they will, but only when public is taken in the context as in public utility or public city. But individuals are not going to buy a flow battery, it is a chemical plant.
I don't think many people are concerned about their batteries being safe for ingestion.