US Patent 7402829 - Nanostructured silicon lithium battery

http://www.freepatentsonline.com/7402829.html

A variety of microelectromechanical applications would benefit from the integration of "on-chip" batteries to further miniaturization and facilitate implantable medical devices. This patent from a UK based company called Nexeon teaches a lithium battery formed from nanostructured silicon. Claim 1 reads:

1. An energy storage device comprising:

an anode comprising an array of sub-micron silicon structures supported on a silicon substrate; and

a cathode comprising lithium, arranged to form a battery.