Batteries made from nanotubes ... and paper :
"Scientists have made batteries and supercapacitors with little more than ordinary office paper and some carbon and silver nanomaterials. The research, published online December 7 in Proceedings of the National Academy of Sciences, brings scientists closer to lightweight printable batteries that may one day be molded into computers, cell phones or solar panels."
See also the first comment. There is also a BBC report on the topic Battery made of paper charges up .