Lithium Battery Fires On Airliners Average More Than One Per Week - AVweb

If you want to certify lithium ion batteries for aviation use, you need to prove that a thermal runaway of a single cell will not damage the aircraft or the surrounding cells in a battery pack. This has to be proven by intentionally damaging a full battery pack and then see what happens. The casing has to withstand the heat and a proper gas exhaust system has to be present and proven to work.
Also in modern battery packs the single cell will be isolated and the pack still functions and delivers energy.

For power banks, phones, laptops and whatever, it looks very different. It scares me when I see the treatment that most of these devices get and how many broken ones I see around, broken and heating wires and connectors, broken cases on many phones, power banks that are thrown around and have cracks and defect wiring, laptops that have a visible bulge at the bottom because the battery has started to degrade and swells up. We had a load of laptops where each one was affected after 4 years of use and my colleagues still ignored this and went on business trips with them.