LiPo at altitude
may I respectfully suggest that you load-test LiPo in REHAB?
LiPo usually is kept together using the coffee-pack principle, meaning that the active ingredients are inside an air-tight bag at (close to) vacuum. The outside air pressure then presses the cathode, the conductive polymer and the anode together, do that beautiful chemistry may occur. Remove said air pressure, and chances are that the spark will be missing, with the sad result that LOHAN will fail to see an ejection while suspended under her massive orbs. Should LiPo fail in REHAB, then you may want to consider using potted Li-Ion. The hard enclosure means that energy/weight is somewhat reduced (chemistry can be the same), but these batteries can work successfully in space (check specs for individual cell types).
Also note that you will get more energy out of the pack if some energy is used to keep the pack itself at temperature.
..mine is the one with a 12.5 kWh / 289V space grade Li-Ion pack in the pocket...