Should there be a clearance between a lithium polymer cell and a charging circuit?
You have 2 problems. Mount a heat-sink on the charger IC using thermal double-sided tape.
Then insert a GP04 red fiberglass insulator between the charger and battery. It can be as thin as 1/16th inch. In surge devices it is also used as a &quot;blast&quot; shield to stop debris from exploding MOV's. Hopefully this will never be an issue for you.
So as in comments you have heat to dissipate instead of trapping it close to the battery. Then the GP04 insulation helps block heat transfer to the battery, and protects the battery from mild impacts. GP04 can tolerate the heat from a damaged Li-Po battery, but the fumes from a burning Li-Po battery are corrosive.