this post was submitted on 27 Dec 2023
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It's pretty clear from the comments that people don't really know anything about lithium batteries. OP actually knows what their talking about for the most part.
First, lithium batteries contain little to no elemental lithium. Just because the molecule has lithium in it doesn't mean it'll react violently with water. Think about table salt. Just because elemental sodium reacts violently with water doesn't mean table salt will.
Secondly, it's not an electrical fire. A lithium battery fire is an exothermic, self sustaining chemical reaction.
Thirdly, that chemical reaction is self oxidizing, so you can't just smother the fire to put it out.
The only way to stop a lithium battery fire is to either let it burn itself out (which is bad because the smoke is highly toxic), or cool it down enough so it can't self sustain. Water is very good at this.
This is the best comment in this thread. Imo a better option is not to change the cooling fluid, but to have a water connection that allows firefighters to flood the battery instead of just spraying on the vehicle
A giant bucket or water balloon?
Personally I'd go for an aqueduct type system
Perhaps liquid nitrogen or even liquid co2 would be something to try to stop the reaction.
Co2 isn't liquid on earth. Maybe you're thinking of supercritical co2, but that turns to gas as soon as it's released into ambient pressures/temperatures
Which is what causes it to cool stuff.
It's not self oxidizing. Old lithium cobalt oxide batteries were, lithium iron phosphate batteries aren't.
Phosphate will decompose into phosphate ions and oxygen given enough energy. The energy of the P--O bond is greater than Co--O but ultimately means that LFP batteries are also self-oxidizing but less so than lithium cobalt oxide
Reference
Find me any proof of any lifepo4 cells having a self-oxidizing event. Spoiler alert: you can't, because there's no reaction that can happen with lifepo4 that will strip oxygen out of phosphate. UL listed companies sell lifepo4 batteries as non-combustible. I highly recommend looking into modern battery chemistry, becase they're way safer than people think.
There's plenty of proof in academic literature. FePO4 is quite stable because of the quirks in iron's valance up to about 500C. But the combination of of lithium skews the valance effects at high temperatures to start losing oxygen at 250C.
Please review the following literature for more information:
How much oxygen are we talking here? I'm guessing not much, as they wouldn't be allowed to sell lifepo4 batteries as non combustible if they had any real chance of causing a self sustaining fire. So level with me so I don't have to trudge through a bunch of academic papers: How much oxygen do they mention?
The stoichometry comes out with 2:1 moles of lfp to diatomic oxygen which is significant
The combustibility you're referring to is a legal definition not a scientific one