As far as I am aware (and I have studied this at some length) there has *never* been an instance where a Lithium battery has caught fire "in normal operation"
Only if you define 'in normal operation' as 'not catching fire'.
The 787 batteries were in normal operation when they caught fire. The Samsung batteries were in normal operation when they caught fire. That they did so due to design flaws merely reiterates my point that they catch fire in normal operation unless you're very careful with the design.
You're right that this has mostly been a lithium issue so far. But any device that stores a lot of energy in a compact form where it's easy to extract is likely to have disastrous failure modes. We understand the disastrous failure modes of jet fuel. We don't understand the disastrous failure modes of
yet-to-be-invented-mega-battery.