MIT announces creation of nano-battery

Imagine a series of infinitesimally fine tubes just billionths of a metre in width coated in a chemical fuel and producing 100 times more electrical power than a conventional battery.

If you think this is a piece of far-fetched sci-fi daydreaming, you haven’t seen the work of a team of nanotechnology pioneers at the Massachusetts Institute of Technology.

The MIT team led by Dr Michael Strano, managed to coat carbon nanotubes with cyclotrimethylene trinitramine, a potent chemical fuel, and used an electric spark or laser to set off a reaction in a bundle of the coated tubes. Carbon nanotubes are known to conduct heat very uniformly – and very rapidly – along their length, at speeds up to 100 times faster than that of metals. Dr Strano’s team were interested in finding out what would happen if a chemical reaction were to occur on these nanotubes; they discovered that the latter served to guide the reaction and accelerate it by an astonishing factor of 10,000. The team’s findings were published in the journal Nature Technology.

The scientists also uncovered another mechanism, even thoug    h at this stage it’s not very well understood: the reaction produces a useful voltage, which the MIT team have dubbed “thermopower waves.” A gram of nanotubes bundles will generate 100 times more energy than the equivalent weight in a lithium ion battery, and the reaction can be initiated with a tiny energy input no greater than the push of a finger. Unlike conventional batteries, the nanotube alternative never loses any stored energy when left to languish in the kitchen drawer, and they do not require toxic, non-renewable metals to manufacture, either.

The new nanotube electrode was made using a cumulative layering technique: base material was dipped into a solution containing either positively or negatively charged carbon nanotubes. Placing layers of the two different types together generates a magnetic field which pulls them together, effectively self-assembling the electrode.

Tests showed that there was zero deterioration after subjecting the nanotube battery to over a thousand charge-discharge cycles.
The MIT team’s work builds on earlier work conducted at Sanford University, which explored the use of silicon nanotube electrodes.
Nanotube batteries could well revolutionise the ways in which we use a vast range of electrical devices, from the smartphone right up to the electrically powered car.

However, there is a great deal of development to be done first. Electrodes capable of powering bigger devices like road vehicles will need to be much thicker than the few microns used in the experimental work. Researchers are hoping that a new technique of spraying the base material with a nanotube solution rather than dipping them will speed up the process, but this is still at a developmental stage. In addition, carbon nanotubes are still scarce in number, even though several nanotechnology firms are trying to develop efficient ways of increasing production.

Finally, the “thermopower wave” phenomena also clearly requires further investigation; the voltage yielded by that chemical reaction has to be safe and controllable in order to be extended to domestic use, and the jury is still out on that right now.