Li-ion is a widely deployed technology that isn't very good. Like coal.

This battery chemistry is inherently fragile. Drive a nail through a Li-ion battery and it will explode. Tesla had to put a titanium plate under their battery after some fires from punctures by road debris. If a Li-ion battery overheats, it will go into thermal runaway and increase its temperature until it catches fire. Overcharging alone is sufficient to do this. It takes about six safety devices to make a Li-ion battery reasonably safe. Leave some of them out, and you get the hoverboard debacle.

There are safer battery chemistries, such as LiFePO4, but you give up about 14% energy density.