What nobody talks about is that much of the lithium electrolyte in lithium ion batteries is in the chemical form of lithium hexafluorophosphate (LiPF6). Burnin

What nobody talks about is that much of the lithium electrolyte in lithium ion batteries is in the chemical form of lithium hexafluorophosphate (LiPF6). Burning produces nontrivial amounts of hydrogen fluoride and clouds of hydrofluoric acid. In the short term, these are horrifically toxic (reactive). They'll bond with just about anything, including etching glass. The impact on living tissue is nightmarish and unlike some other strong acids, protracted because it absorbs rapidly through skin and starts substituting things in your biochemistry. There are also a variety of other excitingly unstable fluorinated compounds floating around. I have a suspicion that at some point we're going to stop talking about "Hey it's a fire that won't go out, we have to use too much water, our tanker trucks aren't equipped for this" and start talking about "Hey it's a fire that boils off what is very nearly a chemical weapon. Evacuate a mile downwind and let it burn". And then we're going to ban the more fire-prone chemistries in stationary and vehicular applications. What event is going to trigger that? I think the most likely thing is a mass casualty event in a deep tunnel traffic jam where the pileup ends up igniting. Obligatory reading: https://www.science.org/content/blog-post/things-i-won-t-touch-1 https://www.science.org/content/blog-post/things-i-won-t-tou... And on this specific threat: https://www.nature.com/articles/s41598-017-09784-z https://www.nature.com/articles/s41598-017-09784-z