[geon]

Yes. Eventually, Li-Ion batteries will "puff up" due to chemical degradation and may even spontaneously catch fire.

https://www.reddit.com/r/askscience/comments/55q7py/why_do_l...

[Pete_D]

This always makes me nervous. If I have some old laptops lying around, how worried should I be about them exploding? Does it only apply if they're in use?