Claiming that battery chemistry itself hasn't improved is like claiming that the physics constants haven't changed... scratch that, it is indirectly claiming th

Claiming that battery chemistry itself hasn't improved is like claiming that the physics constants haven't changed... scratch that, it is indirectly claiming that physics haven't changed. This seems like it's a few steps from a tautology. If you look at this graph ( http://en.wikipedia.org/wiki/File:Energy_density.svg http://en.wikipedia.org/wiki/File:Energy_density.svg ), which is from a wikipedia section linked in the article, there are materials that hold more energy both per unit volume and unit mass than gasoline, we just haven't been able to exploit them yet. Isn't that the whole of materials engineering progress?