I actually think the reason we don't have electric airplanes has to do with traction vs propulsion.
Eg: spinning a jet engine to propel air backwards is very different than spinning a motor that is (through a series of solid objects) directly connect to the ground.
and while a battery is only 1/5th density, the motors on a tesla deliver 3x the range per energy compared to a prius. (not true break even, but impressive that one of the most efficient hybrid ICE cannot compare KWh for KWh to a battery + electric)
No it's just energy density. Hydrocarbon fuels have more. There's also the benefit that getting lighter as you expend fuel increases range (batteries don't meaningfully change mass when they discharge).
Nothing about electric powertrains causes any problems here: it's just hydrocarbon fuel is more energy dense. It's not inconceivable you could build a hybrid electric aircraft if a suitably high power hydrocarbon fuel cell was developed, since removing the combustion stages from a jet engine would simplify the design considerably.
Eg: spinning a jet engine to propel air backwards is very different than spinning a motor that is (through a series of solid objects) directly connect to the ground.
and while a battery is only 1/5th density, the motors on a tesla deliver 3x the range per energy compared to a prius. (not true break even, but impressive that one of the most efficient hybrid ICE cannot compare KWh for KWh to a battery + electric)