What's the difference, besides playing lawyer with words? If you have masses of
two substances that react energetically and exothermically, densely packaged in
the same volume, with a deliberately thin separator, expect trouble.
The ideal battery would keep the reactive components separated. A fuel cell, or
its liquid equivalent, would keep the reactants in separate tanks and only pipe
in what's needed into the reaction space. Something like zinc-air admits one
reactant from outside.
Primary batteries tend to be safer than rechargables. I wonder if airplanes
could use primary batteries.
Seems like bad economics to ground a fleet of roughly $200 million planes to
save about 1000 pounds per.
About 25 years ago or so, the US Navy came up with Hydrogen fuel cells.
Not like what we have now, IIRC. They were essentially a gas cylinder
with Hydrogen gas in it under pressure, and when fully charged it was
like 90 psi, and it dropped in pressure as it discharged. Do not know
what the energy density or construction was, and they would likely be
pretty heavy unless they used Aluminum cylinders/chambers.
They were certainly a rechargeable design. Don't know if such a thing
would be a suitable replacement. Hydrogen is flammable. It would have
to be purged in an emergency circumstance.