Nintendo DSi Information Needed?

I was thinking of buying a Nintendo DSi tomorrow so I could play around with it while I’m on my 24 hour flight tomorrow, I was wondering how exactly are they powered, I can’t seem to find this information anywhere. Do they require like aa batterys? or do they have a built in rechargeable battery pack or something. Also can I plug it into a power point, that would be useful since I will have a power points on the plane (does it come with one or would i need to purchase it separate?).