CMOS Battery or similar for iPhone Location

I have an iPhone 7. I want to know where the CMOS Battery or similar to CMOS Battery for iPhone.

Please let me know where it is by showing a diagram if there is one.

If you cannot show me, let me know the parts close to it. Thank you in advanced!

All power on the iPhone comes from the main battery which is a big lithium ion battery taking up most of the case.

Settings etc are stored in internal nand flash normally and not the CMOS chips that PCs used to use with the real time clock being updated via internet connection (Apples own time servers) or via the mobile phone network.

A full breakdown can be found on the ifixit site here and step six shows you the battery.