IT·Science Talk

ELI5: why do lithium batteries catch fire, and should I worry about my e-bike?

I just bought an e-bike for commuting and now every week I see a news clip about some apartment fire caused by one. I charge mine in the hallway overnight.

What is actually happening inside a battery when it catches fire? Is it a cheap-battery problem, a charging problem, or just bad luck? And practically, what should I be doing differently?