Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Using carbon nanotubes in lithium batteries can dramatically improve energy capacity

21.06.2010
New method produced up to ten fold increase in power

Batteries might gain a boost in power capacity as a result of a new finding from researchers at MIT. They found that using carbon nanotubes for one of the battery's electrodes produced a significant increase — up to tenfold — in the amount of power it could deliver from a given weight of material, compared to a conventional lithium-ion battery. Such electrodes might find applications in small portable devices, and with further research might also lead to improved batteries for larger, more power-hungry applications.

To produce the powerful new electrode material, the team used a layer-by-layer fabrication method, in which a base material is alternately dipped in solutions containing carbon nanotubes that have been treated with simple organic compounds that give them either a positive or negative net charge. When these layers are alternated on a surface, they bond tightly together because of the complementary charges, making a stable and durable film.

The findings, by a team led by Associate Professor of Mechanical Engineering and Materials Science and Engineering Yang Shao-Horn, in collaboration with Bayer Chair Professor of Chemical Engineering Paula Hammond, are reported in a paper published June 20 in the journal Nature Nanotechnology. The lead authors are chemical engineering student Seung Woo Lee PhD '10 and postdoctoral researcher Naoaki Yabuuchi.

Batteries, such as the lithium-ion batteries widely used in portable electronics, are made up of three basic components: two electrodes (called the anode, or negative electrode, and the cathode, or positive electrode) separated by an electrolyte, an electrically conductive material through which charged particles, or ions, can move easily. When these batteries are in use, positively charged lithium ions travel across the electrolyte to the cathode, producing an electric current; when they are recharged, an external current causes these ions to move the opposite way, so they become embedded in the spaces in the porous material of the anode.

In the new battery electrode, carbon nanotubes — a form of pure carbon in which sheets of carbon atoms are rolled up into tiny tubes — "self-assemble" into a tightly bound structure that is porous at the nanometer scale (billionths of a meter). In addition, the carbon nanotubes have many oxygen groups on their surfaces, which can store a large number of lithium ions; this enables carbon nanotubes for the first time to serve as the positive electrode in lithium batteries, instead of just the negative electrode.

This "electrostatic self-assembly" process is important, Hammond explains, because ordinarily carbon nanotubes on a surface tend to clump together in bundles, leaving fewer exposed surfaces to undergo reactions. By incorporating organic molecules on the nanotubes, they assemble in a way that "has a high degree of porosity while having a great number of nanotubes present," she says.

Lithium batteries with the new material demonstrate some of the advantages of both capacitors, which can produce very high power outputs in short bursts, and lithium batteries, which can provide lower power steadily for long periods, Lee says. The energy output for a given weight of this new electrode material was shown to be five times greater than for conventional capacitors, and the total power delivery rate was 10 times that of lithium-ion batteries, the team says. This performance can be attributed to good conduction of ions and electrons in the electrode, and efficient lithium storage on the surface of the nanotubes.

In addition to their high power output, the carbon nanotube electrodes showed very good stability over time. After 1,000 cycles of charging and discharging a test battery, there was no detectable change in the material's performance.

The electrodes the team produced had thicknesses up to a few microns, and the improvements in energy delivery only were seen at high-power output levels. In future work, the team aims to produce thicker electrodes and extend the improved performance to low-power outputs as well, they say. In its present form, the material might have applications for small, portable electronic devices, says Shao-Horn, but if the reported high power capability were demonstrated in a much thicker form — with thicknesses of hundreds of microns rather than just a few — it might eventually be suitable for other applications such as hybrid cars.

While the electrode material was produced by alternately dipping a substrate into two different solutions — a relatively time-consuming process — Hammond suggests that the process could be modified by instead spraying the alternate layers onto a moving ribbon of material, a technique now being developed in her lab. This could eventually open the possibility of a continuous manufacturing process that could be scaled up to high volumes for commercial production, and could also be used to produce thicker electrodes with a greater power capacity. "There isn't a real limit" on the potential thickness, Hammond says. "The only limit is the time it takes to make the layers," and the spraying technique can be up to 100 times faster than dipping, she says.

Lee says that while carbon nanotubes have been produced in limited quantities so far, a number of companies are currently gearing up for mass production of the material, which could help to make it a viable material for large-scale battery manufacturing.

Source: "High-power lithium batteries from functionalized carbon nanotube electrodes." Seung Woo Lee, Naoaki Yabuuchi, Betar M. Gallant, Shuo Chen, Byeong-Su Kim, Paula T. Hammond, & Yang Shao-Horn. Nature Nanotechnology. 19 June 2010.

Jennifer Hirsch | EurekAlert!
Further information:
http://www.mit.edu

More articles from Power and Electrical Engineering:

nachricht Did you know that the wrapping of Easter eggs benefits from specialty light sources?
13.04.2017 | Heraeus Noblelight GmbH

nachricht To e-, or not to e-, the question for the exotic 'Si-III' phase of silicon
05.04.2017 | Carnegie Institution for Science

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Molecular libraries for organic light-emitting diodes

24.04.2017 | Life Sciences

Research sheds new light on forces that threaten sensitive coastlines

24.04.2017 | Earth Sciences

Making lightweight construction suitable for series production

24.04.2017 | Machine Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>