Still in the developing stages, and more than one type, the right kind of Aluminum-Air battery could change everything for Drones/Multirotors.
Some say that such a battery would have a "low discharge rate" for use in Drones/Multirotors - but reinterpreted, a "SLOW discharge rate" is a lemon waiting to be made into lemonade.
Because it would have a low/slow discharge rate, you would have to increase the overall battery assembly, either in the size or number of batteries or cells. - That's not a bad thing, that's a GOOD thing !
If you could use the right kind of Aluminum-Air battery(ies), when you made up in overall battery power to make it useful for Drones/Multirotors, due to the potentially very light weight, you might end up with as much total battery weight as you would have with whatever batteries you are using now.
- Still think this is a bad thing, or going nowhere???
Bottom Line: You might end up with somewhere around the same weight in batteries, but because you actually have more battery reserve (Due to including more batteries or battery cells, in turn due to the low/slow discharge rate) You could in the end have a much longer flight duration !
- and that is a very GOOD thing !
Sample videos from Youtube...