Roughed-up carbon nanotubes could help build better batteries and fuel cells


May 31, 2012

This drawing shows a double-walled carbon nanotube. Each tube is made of a rolled-up sheet of carbon that’s one-atom thick (Image: Guosong Hong/Stanford University)

This drawing shows a double-walled carbon nanotube. Each tube is made of a rolled-up sheet of carbon that’s one-atom thick (Image: Guosong Hong/Stanford University)

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Stanford researchers have found that concentric carbon nanotubes, with the outer layer riddled by defects and impurities, could be a cheap alternative for some of the platinum catalysts that convert hydrogen and oxygen into water in fuel cells and metal-air batteries.

Nanotubes are made of graphene, a one-atom-thick rolled-up sheet of carbon. Abundant structural defects on the outside of the nanotube increase the kind of catalytic reactions that are vital to batteries and fuel cells. But if the inside of the nanotube is damaged, its conductivity drops uncontrollably, degrading performance. Damaging the outside of a frail one-atom-thick structure while leaving the inside intact, however, appeared to be a nearly impossible feat.

The Stanford team solved this dilemma by building structures made of two to three concentric nanotubes. Treating the multi-walled nanotubes in a chemical solution only damaged the outer tube, increasing the number of defects and impurities on the outside but leaving the inside intact.

Originally, the team planned to test the effect of nitrogen impurities alone. But by a pure stroke of luck, traces of iron, the growth seeds used to manufacture the carbon nanotubes, were added into the mix. When the impurities (0.24 percent iron and 5.3 percent nitrogen) were chemically cleared out, the overall performance dropped, suggesting that the impurities do indeed play a vital role in the structure.

In fact, the researchers found that the performance of their nanotubes is very close to platinum, and say that the high stability of the design makes them the perfect candidate for fuel cells and metal-air batteries- lithium-air in particular.

"Lithium-air batteries are exciting because of their ultra-high theoretical energy density, which is more than 10 times higher than today's best lithium ion technology," said Prof. Hongjie Dai, co-author of the study. "One of the stumbling blocks to development has been the lack of a high-performance, low-cost catalyst. Carbon nanotubes could be an excellent alternative to the platinum, palladium and other precious-metal catalysts now in use."

The findings have been published in the May 27 online edition of the journal Nature Nanotechnology.

Source: Stanford University

About the Author
Dario Borghino Dario studied software engineering at the Polytechnic University of Turin. When he isn't writing for Gizmag he is usually traveling the world on a whim, working on an AI-guided automated trading system, or chasing his dream to become the next European thumbwrestling champion. All articles by Dario Borghino

Wow what a news lol. This was known like 5-6 years ago at the least. I've read about battery nano technology few years back. That it would make the charge for up to 20 times longer then usual batteries. Imagine rechargeable accumulators based on same tech. This will be basically unlimited use (500-600 recharges) for those babes. Can't wait for this to come out more or less officially. I need this type of batteries for my work.

Kirill Belousov

The problem is that the is currently no Graphene/Carbon Nanotube fabrication plants mass producing chips, fibre and components. Despite how brilliant they are, if there is no massive investment like we have had for Silicon, they will not be adopted.

Graphene is the future, but we have been anchored to the past. However if Apple decides to source and manufacture its future products in its own factories because costs in China have risen, well that is one company flush with cash and not afraid to spend it.

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