Its going to be never
......Its specific power is 0.37 KW-h/Kg which by my quick calcs requires 300 Kg of battery to produce 112 KW (150 HP) for one hour. 300 KG is about 650 lbs. Lithium-Ion is about 1/3 to 1/2 the specific power of the Zinc-Air so would be 2 to 3 times heavier for the same power.
Unfortunately it is going to be awhile before electric power is available for aircraft.
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Bob Parry
Recreational flying in a local area, yes, replacing the ICE for cross country flights, never.
You just described a 650 pound battery that replaces 72 pounds of 100LL. That ain't going to fly.
As Supercaps go up in energy storage per volume, they go down in discharge rate. Its inherent to the technology. Pouring another billion in won't change that.
Being an EE, I'm also a huge proponent of electric power. Besides the fact that I like all things that run on electrons, it allows getting energy from any source: solar, wind, tide, fossil, or nuclear.
This struggle is not new just because oil prices went up. Battery energy density has been strongly driven for decades because of mobile computing & communication, with some improvements via new materials.
Unfortunately, enthusiasm combined with strong desire won't change the physics. The only material that could solve this problem is unobtainium.
Hydrogen fuel cells have a chance, but their own problems which must be overcome. That's still a liquid fuel that you won't get from the wall socket in your hanger. Also, I'm not sure that it wouldn't just be better to burn the hydrogen in an ICE than make electric power from it.
Cars are a different story as one already pointed out. In that case the limited range or weight of battery solutions is not such a problem. Even if electric cars only replaced ICE for local driving that would take a huge burden off of gas demand.
Similarly, battery powered ultralights or motor gliders might make sense.
Jet aircraft, and hence Jet A, is not going away even in the wildly speculative future. The best future hope of GA is to use JetA. Diesel is the way to go.