This rechargeable lithium battery is specially designed to be used in combination with your Raspberry Pi 5. It will power the Real-time clock when the board is disconnected from the mains. It comes with double-sided tape to secure the battery to a housing.
The battery comes with a compatible connector. This can be attached to the special backup battery head, which is located next to the USB-C connector (labeled BAT). When the Raspberry Pi is disconnected from the mains, the RTC will use this battery for power. The moment the board is connected to power, the battery will charge.