Lithium ion might not be the battery tech for high energy density uses once we work out some other, non battery technologies. Aluminum-air batteries [1] are we

Lithium ion might not be the battery tech for high energy density uses once we work out some other, non battery technologies. Aluminum-air batteries [1] are well studied in the past decade and there is lots more research going on there. Currently the state of the art for such a battery is about 4.7 MJ/kg and the theoretical maximum is as high as 28.8 MJ/kg, at which point the mass of the turbopumps and other fuel handling parts might make up the difference. Of course there are issues, primarily the fact that they're not rechargeable and have to be chemically recycled. It's currently too expensive to do that now, but once we can do it economically, each airport will just have to have a stock of batteries and a robot to swap them on the jet and we'll have electric flight. [1] https://en.m.wikipedia.org/wiki/Aluminium–air_battery https://en.m.wikipedia.org/wiki/Aluminium–air_battery