I'v heard from my safety volunteer colleague that damaged (or neglected) lithium-ion powered devices should be regarded as malicious fire hazard.

So unless you actively intend to set your own car on fire I urge you to end this habit and send the broken phone to an adapted recycling procedure.

(This is also why unrelatedly to the many pollution issues, throwing lithium-ion into landfill is like setting up a time bomb for our kids)