[chrisb]

These are apparently not large EV-type rechargeable lithium batteries, as I immediately assumed.

From the article: "Aricell makes lithium primary batteries for sensors and radio communication devices". A "primary battery" is non-rechargeable; and given the use-cases mentioned I expect each individual battery is fairly small.

Of course, when there are 10s of 1000s of them together that's still a lot of energy to burn.

[kees99]

Primary, non-rechargeable lithium batteries typically contain metal lithium [0], and are actually more likely to catch fire when mishandled, compared to Li-ion stuff.

Specifically, most common Li-ion fires start when overcharged (especially with high current and in cold), and from short-circuits (e.g. when pierced). But only have a very small chance of spontaneously igniting from just disassembly alone [1]. Still non-zero chance, don't open them!

Primary/metal lithium batteries, on the other hand, are much more likely to burst into flames when opened. Notably, lithium-iron disulfide (AA/AAA "alkaline replacement") cells are notorious to do that just from air exposure, even if one is very careful to not short/pierce anything.

[0] https://en.wikipedia.org/wiki/Lithium_metal_batteries

[1] https://www.youtube.com/watch?v=uI1eRy0uBI8

[bitexploder]

And the large type batteries are just made up of a bunch of smaller cells, typically. Stuff that can fit in a flashlight.