Graphene

Of course I love this stuff. Unfortunately it is all still very much in a lab somewhere and must take a lot of gestation. The vanadium battery, which requires no special manufacturing design input has so far been gestating for twenty years.

This is still worth knowing about even though it very much a lab curiosity similar to nanotubes. However, if it could ever be made cheaply enough, it promises to be an excellent material for manufacturing a high density ultra capacitor. Right now we are just beginning to speculate.

Solution chemistry does not need magic at the manufacturing level to work, which is why it has dominated battery design. And Vanadium chemistry works because it does not consume the furniture.

So though graphene is obviously a wonderful material, it is also just as likely unavailable for decades.

What is intriguing is that it is working at the property levels of diamonds. Imagining a manufacturing process that can produce something like this, beggars the imagination. So I remain rather skeptical. We have had buckyballs for forty years and nanotubes almost as long. Both showed up naturally as combustion products if I recall correctly.

It would be wonderful to see a one atom thick sheet rolling out of a machine and carbon is the one element that could do it.



Jay Draiman has left a new comment on your post "Vanadium Battery Discover Acticle": Ultracapacitors may be the answer to energy storage

Regenerative braking strategies are moving beyond automobiles and into the more broad category of regenerative. What goes up must come down! Is now as applicable as What speeds up must slow down!
Many industries can significantly reduce their carbon footprint by designing ultracapacitors into their machinery. The goals is regeneration of lost energy. Similar to regeneration of lost energy during braking, other machinery loses energy.

As an example, construction and cargo cranes can recapture lost energy to be utilized as an assist to bring the crane back up. Another example is an elevator. Elevators come in many sizes. From freight and passenger elevators to mining and aircraft elevators. The amount of energy that is lost during the decent is immense and designing a bank of ultracapacitor to instantly catch this energy is not difficult. Braking is aided by a motor that acts as a generator, converting kinetic energy to electrical energy. If the electrical energy is passed through brake resistors, the energy gets dissipated as Joule heat; if it is captured by energy storage device such as ultracapacitors, there will be less heat dissipation + regeneration.

Or, you may want to use the energy in as a backup emergency system in the event of a power failure. For example, how many times have we experienced a ‘stuck’ elevator. We have heard of people spending hours and even days in these situations. With ultracapacitors, you can have enough energy storage to get the elevator to the designated floor with the doors open.

Many industries can significantly reduce their carbon footprint by designing ultracapacitors into their machinery. If you have an application that could benefit from regeneration of lost energy or emergency power backup and would like to know a deeper understanding of how a it could be designed into your application, all you have to do is ask an expert in this field.

So far, ultracapacitors sweet spot has been applications that require quick burst of high power and can quickly be recharged

Many applications capture the braking energy to replenish the ultracapacitorss (examples: buses, trucks, trains, and elevators). This sweet spot may be changing due to a recent nanotechnology discovery.
University of Texas at Austin, mechanical engineering professor Rod Ruoff has achieved a breakthrough in ultracapacitors by using "graphene". 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.”

After about nine months of research with the new material, they have shown storage abilities similar to those of ultracapacitors already on the market, and they believe graphene's ultra thin structure will allow for sheets of the material to be stacked to increase energy storage and possibly double the current capacity of ultracapacitors. This would allow ultracapacitors to expand into many other renewable and clean energy application for both solar power and wind farms.
Graphene is a one atom thick structure of bonded carbon atoms that are densely packed in a honeycomb crystal lattice. It is best described as an atomic scale chicken wire of carbon atoms and their bonds.
Graphene is strong enough to withstand diamond cutters and is one of the most expensive materials available today. Since it is currently so expensive, it will require some development before it is economical viable for mass production in ultracapacitors. \

This research is exciting and maybe we will see the "new super battery" sooner than we think.

Graphene racks up the charge

25 September 2008

Researchers in the US have used graphene, sheets of carbon that are just one atom thick, to improve the performance of energy-storage devices which could supersede batteries in electric cars.

Rod Ruoff and colleagues at the University of Texas at Austin say the vast surface area of graphene can be exploited to store greater amounts of charge in an ultracapacitor - a device that combines the advantages of a capacitor and a battery.1

Batteries store and release chemical energy slowly and are apt to degrade over time - but they can pack in huge amounts of charge. Traditional capacitors, meanwhile, soak up and release electrical charge in rapid bursts - useful when starting power-hungry engines - but can't store much of it. Ultracapacitors have a storage capacity many thousands of times greater than conventional capacitors, though they need to improve still further to rival battery storage.

'If we could get the energy density of an ultracapacitor to the level of a lead acid battery this would be a massive step forward - and maybe graphene could do this,' says Ruoff.

Ultracapacitors work by suspending electrodes with high surface area - such as highly porous carbon - in an electrolyte. When the electrode is charged with ions or electrons, the electrolyte polarises so that oppositely-charged ions nestle against the electrode surface, producing a highly dense electrical charge within the electrode.

'Because graphene has such a high surface area, if all of it were available to polarise the electrolyte the amount of charge we could dump on it would be very high,' says Ruoff. The researchers used a previously developed technique to make chemically modified sheets of graphene - starting with graphite oxide, shaving it into thin strips, and then chemically reducing the oxide to create carbon sheets one atom thick possessing a small amount of oxygen, hydrogen and nitrogen. The flexible sheets are then mixed with an electrolyte such as potassium hydroxide. They wrap themselves around the electrolyte, forming a close association.

In this way the US team made an ultracapacitor that could store 135 farads per gram of material, comparable to good current ultracapacitors. Ruoff says theoretical predictions suggest graphene's ability to store electrical charge could be about double that of current commercially used materials.

There has been a flurry of interest recently in the use of carbon nanotubes as electrode materials for ultracapacitors, but Ruoff believes that graphene could have the edge over these materials. 'With nanotubes much of the inner surface area can remain inaccessible to the electrolyte,' he says.

One recent exotic example of an ultracapacitor based on carbon nanotubes has been described by researchers in China, who attached highly porous clumps of manganese oxide ions onto stalks of carbon nanotubes protruding from a metal foil. The high porosity of the manganese oxide allows it to harbour a high density of ions, enabling the structure to hold around twice as much charge as conventional ultracapacitors.

Mike Barnes, who works with ultracapacitors at the University of Manchester in the UK, is impressed by Ruoff's modified graphene device. 'The system they are using seems to give very competitive results even at this early stage of the research process,' he comments.

Simon Hadlington