How to Make a 9V Rechargeable Lithium ion Battery DIY

Hi, everybody
These days, this is rare, but still some devices are equipped with 9-volt batteries.
The problem is that they are constantly discharged, and if they are changed every time, it is expensive.
So I decided to make a 9-volt battery myself and charge it if necessary.
Here are the links to the components from the video:
1. DC-DC converter - alli.pub/6ew9nt
2. Charging board with double protection function -alli.pub/6ew9sa
3.I found the battery in my stocks, if you don't have one, then this battery will be perfect for you (you can put 2 pieces in parallel) alli.pub/6ew9um