alt Hacker NewsI don't know what chemistry exactly these cells are using, but in sodium-ion batteries, prussian blue analogs as they are called are common anode materials. Overcharging these cells can lead to a release of hydrogen cyanide gas, notoriously known as Zyklon B.
It has damped my enthusiasm for perusing it as a potential future home energy storage solution.
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Just adding to what others have already said — overcharging the cells is not something you're supposed to be doing. Overcharging even today's common Li-ion cells, i.e. those in your phone, vacuum, EV or home storage, will lead to comparably spectacular results.
Just wait until you find out about hydrogen sulfide from overcharged car batteries.
Also, I think HCN can be scrubbed by adding a special absorptive cap onto the battery.
Its metallic sodium. Its about 30 times more volatile than Lithium. We don't use metallic sodium for almost anything industrial because of this volatility. I assumed there would be some mixed Li-Na-ion batteries. A pure Na-ion battery is an explosive waiting to go off. Putting these in a car...seems rather like a poor choice unless you are a personal injury lawyer.
Do you have any link for the claim that overcharging can produce cyanide?
I have never heard such a thing and all the articles that I have seen about overcharging concluded that such batteries are much safer during overcharging than other kinds of batteries, the worst case effect being battery swelling.
In normal conditions, even during overcharging there are no obvious chemical reactions that could produce hydrogen cyanide.
For instance, at
https://pubs.acs.org/doi/10.1021/acsenergylett.4c02915
it is said that cyanide release can happen only at temperatures above 300 Celsius degrees. Such temperatures cannot be reached in normal conditions.