Batteries from paper

Ink loaded with carbon nanotubes can be brushed onto paper–in this case, forming the Chinese characters for "conductive". Such nanotube-impregnated paper could lead to advanced, lightweight batteries. Plain white office paper could be the basis for efficient batteries. Scientists have converted sheets of them into efficient electrical storage devices using ink loaded with carbon nanotubes.

To devise the novel paper batteries, researchers in  Stanford University, have  colleagues coated plain copy paper with black ink made with single-walled carbon nanotubes, which are electrically conductive pipes only billionths of a meter wide. Positive and negative electrodes—cathodes and anodes—were then applied as slurries dried on the nanotube-impregnated paper. The cathodes were made from lithium manganese oxide nanorods, and the anodes made either from nanopowders of lithium titanium oxide or nanowires with cores of carbon covered with shells of silicon.

The batteries were then dipped in an electrolyte of lithium hexafluorophosphate solution to connect the electrodes and sealed in a pouch. In this setup the nanotubes collected current from each electrode. The researchers say that incorporating carbon nanotube paper into conventional rechargeable batteries could reduce their weight by up to 20 percent.

This reduction could help make electric and hybrid vehicles more feasible and could lead to longer-lasting mobile phones, laptops and other portable electronics. The carbon nanotubes bonded very strongly to the paper, obviating the need for adhesives that decrease performance and significantly increase production costs. The battery could also bend and curl without losing its ability to conduct a charge and can be easily laminated into flexible computers to power the devices. The team noted in their paper that its technique is easily scalable for mass production, and that the ink could even be painted on with brushes, if desired.