MIT engineers developed a fuel cell that offers more than three times as much energy per pound compared to lithium-ion batteries. Powered by a reaction between sodium metal and air, the device could be lightweight enough to enable the electrification of airplanes, trucks, or ships.
This actually looks pretty promising. I hope it works out! I honestly could see this being incredibly useful for stuff outside of aviation too. If you can keep the metals hot, you could potentially run cargo ships and other large vehicles off this stuff too. Cruise ships and certain types of power storage also come to mind.