That’s not necessarily true, though it is also what I thought as of just a few days ago.

www.youtube.com/watch?v=UpqaQR4ikig

At least based on the information in this video from MKBHD, excessive heat is actually what causes rapid degradation of smartphone batteries. Super fast charging phones actually work by reducing the overall heat to the battery through engineering designs, such as by splitting the battery into two parts instead of having one entire battery that gets hot. In this way, a phone that supports 50W chargers can charge “each battery” at only 25W, instead of one single battery at 50W. The space between the batteries also insulates the heat between then. It’s simple but ingenious really.