RE: BATTERIES: What We Do That Kills Our Battery Cells Gradually - Precautions To Be Taken

If the powerbank and laptop output is the specified voltage range for the battery being charged, then you have no problem. You can buy a portable USB tester meter like this one off Amazon for less than $15 or at less than N3000 in Nigeria at Konga

The image in the left (4.93V and 0.98A) is when I was charging via my PC's USB port. The image on the right (5.14V @ 1.15A) is when I'm using a wall charger. You can see the wall charger has a greater charging current and voltage and hence will charge my battery faster. But the laptop port will do the same job too albeit at a slower pace.