Mophie Powerstation XXL
The Mophie Powerstation XXL is a powerful battery that you can use to charge your Nintendo Switch several times over. Even though it packs a lot of power, it's not so big that you won't want to carry it with you.
This battery is wrapped in fabric, so it is easy to hold onto, won't scratch other stuff in your bag and it looks really nice as well. This battery is as thick as two phones on top of each other and you can slide it into a back pocket in a pinch.
The battery will charge as fast as connecting to the wall, and you can use it to charge your phone and even some computers that rely on USB C connections.