Sanyo NCR18650GA 3.6V 3500mAh

I can imagine a plastic is chosen with a higher glass temperature than the maximum operating temperature of the cell.

All GAs have raised tops that should protude.

It seems obvious to me that it can withstand even higher temperatures, for obvious reasons.

Wut?

It seems obvious to me that the isolation between top and shell / tube of the battery can withstand higher temperatures than the maximum operating temperature of the cell.
Probably a lot higher, and for obvious safety reasons.

But that’s actually kind of what you said too, but i didn’t read it too well, sorry…