Carbon laid out in a one-atom thick layer making a structure called “graphene” is being lab tested as an ultracapacitor by mechanical engineering professor Rod Ruoff at the University of Texas at Austin. Ruoff says, “Through such a device, electrical charge can be rapidly stored on the graphene sheets, and released from them as well for the delivery of electrical current and, thus, electrical power. There are reasons to think that the ability to store electrical charge can be about double that of current commercially used materials. We are working to see if that prediction will be borne out in the laboratory.” (Press Release Link)

Graphene Latticework Artist's Rendering

Graphene Latticework Artist

Graphene is a one-atom-thick planar sheet of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice. What is interesting is that using carbon rather than a metal such as lead, nickel, lithium, or titanium for battery and ultracapacitor materials would change the raw materials requirements dramatically. Carbon is readily available in a multitude of forms so relieving much of the need for mining and processing of metals.

Team 0.5 Graphene Photo

Team 0.5 Graphene Photo

Graphene is the strongest substance known to man, according to a study released in August 2008 by Columbia University. However, the process of separating it from graphite where it occurs naturally, will require some technological development before it is economical enough to be used in industrial processes. The Wikipedia page describes the development of graphene production as in the research stage with several universities looking into techniques. Today graphene is one of the most expensive materials possible; with production processes worked out and demand for volume built up – that can change substantially.

What has been proposed with some success is using graphene structured as an electron transport material with proposals to use it in microelectronic applications. That may have been the clue for Professor Ruoff.

Graphene UC Setup

Graphene UC Setup

Ruoff and his team prepared chemically modified graphene material, then using several types of common electrolytes, constructed and electrically tested graphene-based ultracapacitor cells. The amount of electrical charge stored per weight (called “specific capacitance”) of the graphene material has already rivaled the values available in existing ultracapacitors. Ruoff says, “Graphene’s surface area of 2630 m2/gram (almost the area of a football field in about 1/500th of a pound of material) means that a greater number of positive or negative ions in the electrolyte can form a layer on the graphene sheets resulting in exceptional levels of stored charge. Our interest derives from the exceptional properties of these atom-thick and electrically conductive graphene sheets, because in principle all of the surface of this new carbon material can be in contact with the electrolyte.” Modeling suggests the possibility of doubling the capacity.

Ruoff’s team includes graduate student Meryl Stoller and postdoctoral fellows Sungjin Park, Yanwu Zhu and Jinho An, all from the Mechanical Engineering Department and the Texas Materials Institute at the university. Their findings will be published in the Oct. 8 edition of Nano Letters. The fee based article was posted on the journal’s Web site this week. (The free UT Pdf File Link)

Stoller points out this technology has the promise of significantly improving the efficiency and performance of electric and hybrid cars, buses, trains and trams. Even everyday devices such as office copiers and cell phones benefit from the improved power delivery and long lifetimes of ultracapacitors. Ruoff says significant implementation of wind farms for generation of electricity is occurring throughout the world and the United States, “While it is unlikely that such explosive installation and use of wind can continue at this growth rate for 20 years, one can see the possibilities, and also ponder the issues of scale,” he says. “Electrical energy storage becomes a critical component when very large quantities of renewable electrical energy are being generated.”

Here is a quote to think through – According to the American Wind Energy Association; in 2007 wind power installation grew 45 percent in the US. Ruoff notes if the energy production from wind turbine technology grew at 45 percent annually for the next 20 years, the total energy production (from wind alone) would almost equal the entire energy production of the world from all sources in 2007. The demand for storage is definitely coming.

I expect this will work out to some extent, all-depending on the economics of production costs. Carbon as an electron storage medium is just about the oldest known method and the development of nanoscale electron storage forming very high storage densities comes as a both astonishment and relief. Go guys GO!


Comments

5 Comments so far

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