When hooked with a wire to a receiver, they get their power from the receiver. So they will have to plugged into the wall.
I've not looked into the wireless stuff for several years. Maybe it is better, but it wasn't ready for prime time several years ago.
Here is a pretty current article:
https://www.lifewire.com/wireless-speakers-and-home-theater-1846770
But for more detailed information, I'd research is on
http://www.avsforum.com . Those guys are pretty good on the latest trends.