Thread: Batteries practical and theoretical energy density

Aluminum has energy density 31 MJ/Kg and
83.8 MJ/L vs. gasoline which has energy density 46.4 MJ/Kg and 34.2 MJ/L
http://en.wikipedia.org/wiki/Energy_density
what makes aluminum attractive alternative to
gasoline and especially to hydrogen as energy
carrier.Efficiency of aluminum-air fuel cells is
about 80%.However there is great problem
which lays in difference between theoretical
energy density of aluminum which is 8000 W-h/Kg and practical energy density of Al-air fuel cells which is 1200 W-h/Kg.
http://en.wikipedia.org/wiki/Aluminium_battery
Does anybody know what is making that difference so big?
I understand that battery
needs to have container and electrolyte,
but you need gas tank for gasoline too.
And how much electrolyte is there?!

Maybe something to do with an incomplete reaction of the aluminium?

Possibly the great tendency of Al to form a very stable oxide coating.