MacBook Pro 15" Retina Display Mid 2012 Teardown
The warning label for the batteries says 100 °C. I bet the glue is hot melt and it turns to butter at some temperature well below that. Apple offers battery replacement service so there has to be some reliable way to un-bond the glue.
I bet at about medium well (160 °F or 71 °C) the batteries fall right out.