When choosing a battery the main consideration was maximizing energy density by weight. Current output was not really a concern as the number of cells needed in parallel to have the desired capacity would allow current output far beyond what was needed. This lends itself to Lion batteries, and more specifically the 21700 formfactor. The best option I was able to find was the Samsung 50E 21700 5000mAh 9.8A Battery. I chose these over a version rated for higher current output because they were slightly lighter.

These cells were spot welded into a larger pack using the appropriate thickness and layers of nickel strip and wrapped with Kapton tape. Fish paper insulation was used between series cells to prevent potential shorts.