Power-to-weight ratio of electric motors

I wasn't sure whether to put this in the mechanical engineering board or not but since electrical engineers typically design electric motors, I'll put it here.

From what I hear, all types of electric motors have terrible power-to-weight ratios. So if we were to hypothetically one day have a light-weight battery with the energy density of jet fuel, we wouldn't be able to have an electric 747 because an electric motor with enough power to lift a 747 would be too heavy.

So I was wondering, how would you go about trying to increase the power-to-weight ratio of an electric motor? Are there any institutions doing research on this?

Note: I suppose we wouldn't need batteries to have an energy density as high as that of jet fuel since an electric 747 engine would be a lot more efficient than the combustion version but you get my point.

 PhysOrg.com engineering news on PhysOrg.com >> Researchers use light projector and single-pixel detectors to create 3-D images>> GPS solution provides 3-minute tsunami alerts>> Single-pixel power: Scientists make 3-D images without a camera
 High-temperature superconductors can do a great deal to increase the specific power/power density of electric motors: http://www.powermag.com/issues/depar...Test_1759.html
 Recognitions: Gold Member Science Advisor The other half of an electric motor is its magnetic medium, iron. It takes a lot of iron to carry a weber of magnetic flux. We need an "Unobtanium" alloy of iron that doesn't saturate. Or a lighter magnetic material. You'll get a 1::1 reduction in iron weight for an increase in its ability to carry flux. Iron cobalt and nickel are the three ferromagnetic elements and they're adjacent one another in periodic table. Maybe you'll be the one to find some quirk of nature that'd let engineers operate them around 100 Teslas - now THAT'd be something.... old jim