Just a tad bit more info, standard battery banks seem to play well when Switch is in sleep/off mode, but when you are using it, it doesn't work well. I guess it's better to wait for Switch compatible ones, which also means a higher price tag as well.
EDIT: IIRC, you have access to a chemistry lab at the uni, can't you custom make your battery with the required voltage output? Just a thought, I know the amount of work that will be required. It might be a nice fun way to waste some time. Like creating a collectable item.