“The chemical xenon difluoride is normally a mild-mannered white powder, but when you crush it with the pressure of 1 million times our atmosphere, it turns into a super substance. Due to some weird science, all the energy used to crush that stuff is stored inside its chemical bonds, making it a terrific energy storage device. In layman’s terms, that would be a battery.”
via DVICE:
http://dvice.com/archives/2010/07/battery-breakth.php
As exciting as this sounds, lithium-ion and lithium polymer batteries already pack a tremendous amount of energy in a very dense space. I’m all for improving on this, but technology like this one sounds exceptionally scary-dangerous when you figure the force it takes to form the bonds in these materials. Imagine what would happen if you dropped the thing?
In fact, forget about that, imagine what happens when the decepticons find out you have one 
Real picture of the “formed” energy cube:
