The tiny chip TP4056/YP4056 is a good example. The TP4056 IC is a complete constant current/constant-voltage linear charger for single cell lithium-ion/Lithium Polymer (LiIon/LiPo) batteries. Its ...

This half-inch square ultra-low power energy harvesting LiPo cell charger by [Kris ... configured to charge and maintain a single lithium-polymer cell. The BQ25504 is an integrated part that ...

[Philipp] was looking to add some lithium power for the Launchpad. He used an off the shelf single cell LiPo battery and connected it to the 5V rail of the Launchpad board. It didn’t work.

Lithium-polymer (LiPo) batteries have a higher power density than most other battery technologies. They also deliver a higher nominal voltage per cell: 3.7 V compared to 1.2 to 2 V for other cells.