Thin, Light, Strong, and Energy Dense

Dean Sigler Electric Powerplants, Sustainable Aviation 2 Comments

 2010’s Nobel Prize in Physics went to Andre Geim and Konstantin Novoselov, who extracted graphene from a piece of graphite when they stuck a piece of adhesive tape to it and peeled away a single atom-thick layer of the thinnest, strongest material in the world.

The Nobel Prize web site explains other remarkable properties of this new material.  “As a conductor of electricity it performs as well as copper. As a conductor of heat it outperforms all other known materials. It is almost completely transparent, yet so dense that not even helium, the smallest gas atom, can pass through it. Carbon, the basis of all known life on earth, has surprised us once again.”

With studies in quantum physics and materials science possible, practical applications loom.  “Also a vast variety of practical applications now appear possible including the creation of new materials and the manufacture of innovative electronics.  Graphene transistors are predicted to be substantially faster than today’s silicon transistors and result in more efficient computers.

“Since it is practically transparent and a good conductor, graphene is suitable for producing transparent touch screens, light panels, and maybe even solar cells.

“When mixed into plastics, graphene can turn them into conductors of electricity while making them more heat resistant and mechanically robust. This resilience can be utilized in new super strong materials, which are also thin, elastic and lightweight. In the future, satellites, airplanes, and cars could be manufactured out of the new composite materials.”

This promising material is rapidly being developed into real products, including the world’s most energy-dense supercapacitor, as reported in Gizmag on December 10, 2010.  Scientists at Angstron materials reported energy densities of 86 Watt-hours per kilogram at room temperature and 136 Wh/kg at 86° C (176° F), “comparable to that of Ni-mh (nickel metal hydride) batteries” but, as with most capacitors, much faster charge and discharge rates, and a longer cycle life.

Amps per gram for graphene-based supercapacitor

Dr. Bor Jang, co-founder of Angstron, the developer of this supercapacitor, explains, “This type of supercapacitor is especially attractive for electric vehicle applications where the pairing of supercapacitors with fuel cells or batteries could provide a hybrid system capable of delivering high power acceleration and energy recovery during braking.”

Working with Nanotek Materials and Dalian Institute of Technology in China, Ansgstron credits manufacturing techniques that curve the platelets and prevent the thin* graphene sheets from sticking together and allowing maximum surface area to be achieved for at least some of the material’s superior characteristics.

 The team’s paper “Graphene-Based Supercapacitor with an Ultrahigh Energy Density” is reported in the journal Nanoletters.  The abstract explains, “The key to success was the ability to make full utilization of the highest intrinsic surface capacitance and specific surface area of single-layer graphene by preparing curved graphene sheets that will not restack face-to-face. The curved morphology enables the formation of mesopores accessible to and wettable by environmentally benign ionic liquids capable of operating at a voltage >4 V.”

According to the company, “The world’s largest producer of nano graphene platelets (NGPs), Angstron’s single-layer graphene has exhibited the highest electrical properties including exceptional in-plane electrical conductivity (up to ~ 20,000 S/cm) when compared to other nanomaterials including carbon nanotubes (CNTs) and carbon nanofibers (CNFs).” 

Beyond supercapacitors, NGPs have potential applications in next-generation lithium-ion batteries and fuel cells.  Because they are more easily manufactured than carbon nanotubes and carbon nanofibers, NGPs promise lower costs in all applications.   Because of their strength, NGPs in a sandwich-type matrix could provide a blend of structure, light weight and energy storage that would make them exceptional candidates for use in electric aircraft.

Usually, Nobel Prizes predate practical outcomes by many decades.  This latest development seems to be a fast-track project with short and long-term implications.

*Over 28,000 square feet per gram for a single layer of the material – or about the size of a football field.  (NOTE: Corrected January 19.  Your editor skipped a decimal point or two in the original.)

Comments 2

  1. Hydrogen is smaller then helium!

    (Editor’s note: Thanks for the reminder. I relearn something every day.)

  2. Fletcher is technically correct since you used the word “atoms”, but…

    Hydrogen gas is made up of diatomic molecules which are bigger than helium atoms. Exact size is a little tricky to define here, but helium is a harder gas to contain than hydrogen, so maybe you meant to say that helium is the gas with the smallest *molecules,* which in this case just happen to be monatomic. Leak checking is usually done with helium because it is really good at escaping. The fact that a material can stop helium is much more impressive than if it could stop hydrogen. I think you had the right idea even if you said it wrong.

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