The source RGcloudS recently revealed in a tweet, Apple is using a new charging protocol and power supply chip, which allows the iPhone to realize 40W wired fast charging and 20W MagSafe wireless charging.

RGcloudS said it is not possible to confirm whether Apple will apply this improvement to the iPhone 15 series, and does not rule out the possibility of delaying it to the iPhone 16 series.
Note: Apple’s iPhone 14 series supports a maximum wired charging power of 30W, and MagSafe supports up to 15W charging.

RGcloudS previously revealed that the iPhone 15 series will use stacked battery technology from the automotive sector, which not only has the ability to have higher energy density, but also safer, but in the latest tweets, it said that the technology is delayed to the iPhone 16 series.
Stacked battery cells utilize a manufacturing technique called lamination, in which battery elements and spacers are folded into jagged layers rather than rolled up. With less wasted space within the packaged cells, more active material can be included, which increases the total capacity.
This allows stacked cells to have a higher energy density compared to rolled cells. Heat can also be more evenly distributed within the cell rather than concentrated in one area, which extends the life of the battery.