Best kept secret and works like a charm! I use good ole WD-40 poured into a syringe with a plastic tip. DON’T USE A METAL one to avoid puncturing the battery. Run a line the liquid near the longest edge and orient the battery so that gravity can move it under the battery. From the other side apply some heat just until it feels hot to the touch. The aluminum will dissipate the heat through the glue and help wick the WD-40. Keep running WD-40 until it stops wicking with some more heat if it cooled of. Wait for about 5 minutes, give it some more heat.
You can now start the battery detachment procedure. The battery should come off very easily with little pressure. If you feel any resistance, run some more WD-40. When removed, make sure you clean up all residual WD-40 with acetone or alcohol from all areas. WD-40 is a lubricant and a tiny bit of it should hurt anything, but it will prevent any adhesion.