Yi Cui/Stanford U

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Ultrathin rechargeable lithium-ion batteries have been fabricated on a single sheet of paper, resulting in highly flexible and lightweight portable power sources, according to a study published in ACS Nano by Stanford University researchers (DOI: 10.1021/nn1018158). The advance may provide an integrated power solution for the developing field of paper-based electronics and lead to applications in “smart” packaging and radio-frequency sensing.

To make the batteries, Stanford materials scientists Liangbing Hu, Hui Wu, Yi Cui, and coworkers coated a solid support with a thin film of carbon nanotubes and deposited a film of a metal-containing lithium compound on top of the nanotubes. Then the team deposited the double-layer films on both sides of ordinary paper. In that design, the lithium layers function as battery electrodes and the nanotube films serve as current collectors. The paper is the electrode separator and also serves as a mechanical support.

The new batteries, which are just 300 μm thick, are thinner and more flexible, and they exhibit higher energy density and other electrical advantages, compared with other types of thin batteries, the scientists say. They add that battery performance did not degrade over the course of a 300-cycle recharging test.

Juxtaposing carbon nanotubes and lithium compounds with paper has enabled the team to optimize the device in an ultrathin architecture, says Rice University’s Pulickel M. Ajayan. “Such simple fabrication techniques could prove useful for integrating other nanomaterials for building the next generation of energy-storage devices,” he says.