I hate lithium battery packs, that are built like there is gold bullion inside, which they need to prevent anyone ever extracting.
Again, just now, stripping down a laptop a friend discarded, I wanted to salvage the 18650 cells and charge management pcb.
The battery case is made of PC + ABS (polycarbonate and ABS mix, that seems nearly as tough as Kevlar.) The seams are glued, AND screwed, with security tri-edge philips style screws. Then the batteries are glued into the shell, using some silicone stuff that is tougher than any silicone glue I've ever been able to buy. It won't let go, and is extremely hard to tear. The PCB is also glued into it's slot, same stuff. And it's full-cover screened with white paint on both sides, making trace following impossible.
Why do they bother with this obstructive stupidity? No matter what they do, anyone who really wants the batteries out will get them.