[ClumsyPilot]

A container that traps flammable gasses is called a bomb

This is not usually a design goal

[hobs]

No, a container that contains flammable gasses and then destructively allows them to escape is a bomb, one that just inflates is arguably the equivalent of a self inflating pillow.

[ClumsyPilot]

Gasses create pressure A phone casing is not a pressure vessel This isn’t going to work