Nanotube ink turns paper into batteries

Stanford researchers coat paper with carbon nanotubes and silver nanowires to serve as electricity storage devices. Go ahead, crumple it.

A group of researchers from Stanford University have figured out a way to transform ordinary copy paper into storage units for electricity.

This week a group led by Yi Cui, professor of materials science and engineering at Stanford, demonstrated (see video) the use of an ink consisting of carbon nanotubes and silver nanowires. Once dipped in the ink and then baked, ordinary paper turns into a black paper that can act as a battery or supercapacitor. The paper retains its ability to hold a charge regardless of whether it's bent, crumpled, or rolled.

The ink looks identical to common India ink, which makes sense given the fact that Cui's ink is also made of carbon, albeit carbon nanotubes.

Cui and his team tried the ink on plastic, but found paper to be preferable because of its absorbent properties and its ability to endure crumpling. The ink could also be used as paint to create conductive walls.

The nanotechnology paper would have applications in electricity storage devices connecting to electrical grids, and could last through 40,000 charge/recharge cycles, according to Cui.

Cui said the nanomaterial transfers electricity more efficiently than normal conductors. He sees the paper providing a lightweight storage solution for energy sources, like wind and solar, which contend with the problem of not always being available on-demand. It could also be used in hybrid or all-electric cars.

Ink or printing has become a common method for scientists using nanotechnology to convey unusual properties onto ordinary objects. Innovalight has developed a proprietary silicon ink for ink-jet-manufacturing solar cells . In 2007, IBM and ETH Zurich researchers developed a method for "printing" molecules.

Cui's Stanford team for the ink project includes Liangbing Hu and JangWook Choi, both post doctoral scholars, and Yuan Yang, a graduate student.

Credit: Jack Hubbard/Standford News Service

About the author

In a software-driven world, it's easy to forget about the nuts and bolts. Whether it's cars, robots, personal gadgetry or industrial machines, Candace Lombardi examines the moving parts that keep our world rotating. A journalist who divides her time between the United States and the United Kingdom, Lombardi has written about technology for the sites of The New York Times, CNET, USA Today, MSN, ZDNet,, and GameSpot. She is a member of the CNET Blog Network and is not a current employee of CNET.


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