A power bank has some sort of circuitry, but I am not sure if there is any software on a power bank or if they are only pure batteries, but people are connecting their mobile phones and laptops to them by USB and historically USB sticks represent a medium to transfer malware.
A pure power bank likely cannot - most of them have the data lines not connected to any chips, but rather to resistor networks. However, someone could easily make something that appears to be a power bank but has nasty firmware on it.
You can get data disconnected (power only) USB cables that you could use to plug into a suspect power bank. However, since phones use the data lines to decide how much power they can draw, in disconnected lines they draw the minimum and will charge slower.
You could make up a cable to match your phone, but it gets complicated.
Answering directly to your question. Yes, i believe a power bank can be used to plant malware. If you bought an unknown brand of powerbank or from a questionable source.
One could have a battery that powers a raspberry pi or pi zero in a 'powerbank' case.
Your phone would still charge as if you are plugged into the laptop. Malware can be pushed via adb or other crafted scripts.
In this day and age, you get hacking devices disguised as Power Adapters, Power Strips etc. What's new if a hacking device is guised as a powerbank.
Check out this news article from Gizmodo :)