fantastic plastic

New Scientist is reporting on printable batteries with carbon nanotube (CNT) electrodes.

The batteries were created by George Gruner and colleagues at the University of California in Los Angeles, US, and use the same zinc-carbon chemistry as ordinary non-rechargeable batteries.

To make the battery, a layer of nanotubes is first deposited in the form of “nanotube ink” onto a surface. This layer acts as the charge collector, which removes current from the battery.
Next, a layer of nanotube ink mixed with manganese oxide powder and electrolytes, which carries charge within the cell, is applied on top. This layer acts as the cathode. Finally, a piece of zinc foil – the anode – is applied.
“The batteries are similar to conventional batteries,” says Gruner, “with the electrically conducting nanoscale networks replacing conventional metals and electrodes.”

The researchers also made supercapacitors using the inking technique and plan to combine these with batteries for applications requiring more power.
Furthermore, since both printed batteries and supercapacitors can be made entirely at room temperature, it should be possible to mass-produce them using established printing methods, Gruner says.

IDTechEx points out that

Professor Gruner is also Chief Technical Officer of Unidym Inc a company he funded in 2005 which focuses on nano-structured materials applications for flexible/transparent electronics.

This subsidiary of Arrowhead Research is developing printed carbon nanotube (CNT) technology for applications such as transparent electrodes, thin film transistors, and fuel cells.
The work has been published in Applied Physics Letters.

As reported in Science magazine (”An Integrated Logic Circuit Assembled on a Single Carbon Nanotube”; 24 March 2006; Vol. 311, no. 5768, p. 1735), researchers at IBM in New York and co-workers have created a ring oscillator on a single carbon nanotube.

According to the BBC, running at 50 megahertz,

the circuit is 100,000 times faster than any previously recorded for a device made with a carbon nanotube […].

This article at the New Scientist explains how this research might help to increase the speed of future microprocessors with ever smaller feature sizes:

The problem is that as electrical paths shrink, electrical resistance increases proportionally. Also, the process of doping – adding impurities to the silicon to alter its electrical properties – means that the impurities left behind scatter electron flow, which becomes more of a problem at smaller scales.
The major reason behind the resistance, however, is an odd phenomenon known as plasmonic resonance, in which an electron’s path is hindered when it becomes coupled with vibrations in the surrounding lattice structure. But because the carbon nanotube is a single molecule with electrons passing along the tube, this problem is averted and resistance minimised, even at tiny scales.
Additionally, smaller silicon pathways make it easier for electrons to “jump tract” and leech into other nearby components. But in a nanotube circuit, this would be highly improbable as electrons would be carried down the molecular tract of the nanotube, Appenzeller explains.

Supercapacitors or ultracapacitors use electrodes with very high surface area (e.g. porous activated carbon) and are currently used in niche application such as hybrid vehicles.
Among the advantages over electrochemical batteries are the high charge/discharge rate and stability. However, energy densities are relatively low compared to traditional batteries.

New electrode materials with increased surface area have the potential to make hypercapacitors attractive for a wider range of mobile applications.
The approach developed at MIT’s Laboratory of Electromagnetic and Electronic Systems (LEES), uses vertically-aligned single-walled carbon nanotubes.
From the MIT Technology Review:

Ultracapacitors could allow laptops and cell phones to be charged in a minute. And unlike laptop batteries, which start losing their ability to hold a charge after a year or two, they could still be going strong long after the device is obsolete. “Theoretically, there’s no process that would cause the [ultracapacitor] to need to be replaced,” says professor John Kassakian, another of the researchers.

The main hurdle the new technology is likely to face is not technical but economic. “The nanomaterials are probably a hundred or a thousand times more expensive, today, than the materials that we use,”

Other large surface area materials for ultracapacitors include carbon aerogels and barium titanate.

As reported here, Nantero is using carbon nanotubes (CNTs) for a mechanical-switch type non-volatile memory (NRAM). Ribbons of nanotubes are suspended between raised points on a substrate. Applying a voltage to an electrode beneath a CNT bridge, causes the nanotubes to bend downwards until in contact with the substrate. Due to van der Waals forces, the nanotubes remain in the bent position without any applied voltage. The resulting non-volatility is a big advantage, but apparently speed and memory density are also higher than for standard DRAM.
The Economist (May 2003) likes the technology, too.

[Update:] coverage by Nature (Oct. 2004), for those with access.