Comment by margalabargala
19 hours ago
It's definitely not that cut and dry. Here's a paper with a good breakdown of safety comparisons: https://www.sciencedirect.com/science/article/pii/S2352152X2...
Tldr: while sodium thermal runaways are less dangerous than lithium, they are more likely to happen, and in particular charging a sodium battery to 100% SOC makes thermal runaway significantly more likely than in LFP batteries.
It's true that things like puncture or short circuit are much much less dangerous than with lithium. That is a big part of why the increased thermal runaway risk gets overlooked.
Agreed.
The main thing about LFP is people (stupidly) shove them in a basement or enclosed space because they are "safe".
But the "safe" part is that they outgas hydrogen when in thermal runaway, which, combined with enclosed spaces like basements (where people often have gas heaters or ....), is .... a super super bad idea.
Ironically, in this situation, sodium-ion is worse than LFP in almost every conceivable way - the gas is more flammable, toxic, etc.
People who think sodium-ion is "safer" are being sold a bill of goods.
> the gas is more flammable, toxic, etc
There are many alternative materials for the cathodes of sodium-ion batteries and for now the industry has not settled on one of them as being the best.
The safety properties depend on the cathodic material. The vented gas can be toxic only for one class of materials (Prussian blue analogs) and IIRC none of the currently existing commercial sodium-ion batteries uses this kind of cathodes.
For the other cathode types, the vented gas is hydrogen exactly like in almost any kind of battery, and it is equally flammable for all kinds of batteries.
In the article linked above, the conclusion was that for one kind of cathodic materials, which perhaps is the one used in most currently existing sodium-ion batteries, the risk of damaging the battery by overcharging and the risk of thermal runaway (assuming that the battery management system fails to prevent these), are slightly higher than for LFP but lower than for other lithium-ion batteries.
On the other hand, mechanical damage by puncturing the batteries is less dangerous than for any lithium-ion batteries.
These conclusions are not definitive about sodium-ion batteries, because other cathodic materials will behave differently, and there is still a lot of experience to gain with sodium-ion batteries, so it is certain that the cathodic materials used in 2030 will not be the same as today.
There is also the possibility of releasing hydrogen cyanide during a runaway event for some variants too
That can happen only for the sodium-ion batteries that use 1 of at least 5 possible classes of cathodic materials, i.e. Prussian blue analogs, and it seems that none of the currently existing commercial sodium-ion batteries uses this kind of cathode.
Isn't a better/safer solution than Li or Na is for the industry to switch to solid state?