Earlier quoted context omitted.
It's probably not a fire hazard any more than other regular smartphones. Battery usually only gets somewhat warm when charged at "fast charging" current. My kernel has some patches that enable battery thermal regulation in the power management chip. Battery gets too warm/cold, charging stops.
Would you be willing to share these patches? I'm interested in this.
- regulator: axp20x: Enable over-temperature protection and 16s reset function
- power: supply: axp20x_battery: Setup thermal regulation (experimental)
EDIT: I'm the author of the quoted articles on xnux.eu, just to be clear.