Ever saw the electric version of the goped? it moves well. it uses lead batteries.
here is a dutch company that makes electric bikes;
http://www.sparta.nl/nl/sparta-ION-p...0001&menu=1com
They use ion batteries, look at the funky lower tube, that's where they hide the batteries.
Their rear hub is a large BL motor. It supports up to 25 km/h (so i guess it produces roughly 180 watts of power)
It's not really considred an electric bike, it's a bike withe electric support. I don't know what your goal is?