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Printable batteries

Research News July 2009 

For a long time, batteries were bulky and heavy. Now, a new cutting-edge battery is revolutionizing the field. It is thinner than a millimeter, lighter than a gram, and can be produced cost-effectively through a printing process.

In the past, it was necessary to race to the bank for every money transfer and every bank statement. Today, bank transactions can be easily carried out at home. Now where is that piece of paper again with the TAN numbers? In the future you can spare yourself the search for the number. Simply touch your EC card and a small integrated display shows the TAN number to be used. Just type in the number and off you go. This is made possible by a printable battery that can be produced cost-effectively on a large scale. It was developed by a research team led by Prof. Dr. Reinhard Baumann of the Fraunhofer Research Institution for Electronic Nano Systems ENAS in Chemnitz together with colleagues from TU Chemnitz and Menippos GmbH. “Our goal is to be able to mass produce the batteries at a price of single digit cent range each,” states Dr. Andreas Willert, group manager at ENAS.

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Prototype Nokia phone recharges without wires

Pardon the cliche, but it's one of the holiest of Holy Grails of technology: Wireless power. And while early lab experiments have been able to "beam" electricity a few feet to power a light bulb, the day when our laptops and cell phones can charge without having to plug them in to a wall socket still seems decades in the future.

Nokia, however, has taken another baby step in that direction with the invention of a cell phone that recharges itself using a unique system: It harvest ambient radio waves from the air, and turns that energy into usable power. Enough, at least, to keep a cell phone from running out of juice.

While "traditional" (if there is such a thing) wireless power systems are specifically designed with a transmitter and receiver in mind, Nokia's system isn't finicky about where it gets its wireless waves. TV, radio, other mobile phone systems -- all of this stuff just bounces around the air and most of it is wasted, absorbed into the environment or scattered into the ether. Nokia picks up all the bits and pieces of these waves and uses the collected electromagnetic energy to create electrical current, then uses that to recharge the phone's battery. A huge range of frequencies can be utilized by the system (there's no other way, really, as the energy in any given wave is infinitesimal). It's the same idea that Tesla was exploring 100 years ago, just on a tiny scale.

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Flexible, transparent supercapacitors are latest devices from USC nanotube lab

It is a completely transparent and flexible energy conversion and storage device that you can bend and twist like a poker card.

It continues a line of prototype devices created at the USC Viterbi School of Engineering that can perform the electronic operations now usually handled by silicon chips using carbon nanotubes and metal nanowires set in indium oxide films, and can potentially do so at prices competitive with those of existing technologies.

The device is a supercapacitor, a circuit component that can temporarily store large amounts of electrical energy for release when needed. A team headed by Chongwu Zhou describes it a newly-published paper on "Flexible and Transparent Supercapacitor based on Indium Nanowire / Carbon Nanotube Heterogeneous Films" in the journal Applied Physics Letters (Vol.94, Issue 4, Page 043113, 2009).

Its creators believe the device points the way to further applications, such as flexible power supply components in "e-paper" displays and conformable products.

The device stores an energy density of 1.29 Watt-hour/kilogram with a specific capacitance of 64 Farad/gram. By contrast, conventional capacitors usually have an energy density of less than 0.1 Wh/kg and a storage capacitance of several tenth millifarads.

Zhou, who holds the Jack Munushiun Early Career Chair at the USC Ming Hsieh Department of Electrical Engineering, worked with USC graduate students Po-Chiang Chen and Sawalok Sukcharoenchoke, and post-doc Guozhen Shen.

The group incorporated metal oxide nanowires with carbon nanotubes (CNTs) to form heterogeneous films and further optimized the film thickness attaching on transparent plastic substrates to maintain the mechanical flexibility and optical transparency of the supercapacitors.

Turning sunlight into liquid fuels

Berkeley Lab researchers create a nano-sized photocatalyst for artificial photosynthesis.

Berkeley, CA - For millions of years, green plants have employed photosynthesis to capture energy from sunlight and convert it into electrochemical energy. A goal of scientists has been to develop an artificial version of photosynthesis that can be used to produce liquid fuels from carbon dioxide and water. Researchers with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have now taken a critical step towards this goal with the discovery that nano-sized crystals of cobalt oxide can effectively carry out the critical photosynthetic reaction of splitting water molecules.

"Photooxidation of water molecules into oxygen, electrons and protons (hydrogen ions) is one of the two essential half reactions of an artifical photosynthesis system - it provides the electrons needed to reduce carbon dioxide to a fuel," said Heinz Frei, a chemist with Berkeley Lab's Physical Biosciences Division, who conducted this research with his postdoctoral fellow Feng Jiao. "Effective photooxidation requires a catalyst that is both efficient in its use of solar photons and fast enough to keep up with solar flux in order to avoid wasting those photons. Clusters of cobalt oxide nanocrystals are sufficiently efficient and fast, and are also robust (last a long time) and abundant. They perfectly fit the bill."

Frei and Jiao have reported the results of their study in the journal Angewandte Chemie, in a paper entitled: "Nanostructured Cobalt Oxide Clusters in Mesoporous Silica as Efficient Oxygen-Evolving Catalysts." This research was performed through the Helios Solar Energy Research Center (Helios SERC), a scientific program at Berkeley Lab under the direction of Paul Alivisatos, which is aimed at developing fuels from sunlight. Frei serves as deputy director of Helios SERC.

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Scientists find new way to produce hydrogen

Scientists at Penn State University and the Virginia Commonwealth University have discovered a way to produce hydrogen by exposing selected clusters of aluminum atoms to water. The findings are important because they demonstrate that it is the geometries of these aluminum clusters, rather than solely their electronic properties, that govern the proximity of the clusters' exposed active sites. The proximity of the clusters' exposed sites plays an important role in affecting the clusters' reactions with water. The team's findings will be published in the 23 January 2009 issue of the journal Science.

"Our previous research suggested that electronic properties govern everything about these aluminum clusters, but this new study shows that it is the arrangement of atoms within the clusters that allows them to split water," said A. Welford Castleman Jr., Eberly Family Distinguished Chair in Science and Evan Pugh Professor in the Penn State Departments of Chemistry and Physics. "Generally, this knowledge might allow us to design new nanoscale catalysts by changing the arrangements of atoms in a cluster. The results could open up a new area of research, not only related to splitting water, but also to breaking the bonds of other molecules, as well."

The team, which also includes Penn State graduate students Patrick Roach and Hunter Woodward and Virginia Commonwealth University Professor of Physics Shiv Khanna and postdoctoral associate Arthur Reber, investigated the reactions of water with individual aluminum clusters by combining them under controlled conditions in a custom-designed flow-reactor. They found that a water molecule will bind between two aluminum sites in a cluster as long as one of the sites behaves like a Lewis acid, a positively charged center that wants to accept an electron, and the other behaves like a Lewis base, a negatively charged center that wants to give away an electron. The Lewis-acid aluminum binds to the oxygen in the water and the Lewis-base aluminum dissociates a hydrogen atom. If this process happens a second time with another set of two aluminum sites and a water molecule, then two hydrogen atoms are available, which then can join to become hydrogen gas (H2).

The team found that the aluminum clusters react differently when exposed to water, depending on the sizes of the clusters and their unique geometric structures. Three of the aluminum clusters produced hydrogen from water at room temperature. "The ability to produce hydrogen at room temperature is significant because it means that we did not use any heat or energy to trigger the reaction," said Khanna. "Traditional techniques for splitting water to produce hydrogen generally require a lot of energy at the time the hydrogen is generated. But our method allows us to produce hydrogen without supplying heat, connecting to a battery, or adding electricity. Once the aluminum clusters are synthesized, they can generate hydrogen on demand without the need to store it."

Khanna hopes that the team's findings will pave the way toward investigating how the aluminum clusters can be recycled for continual usage and how the conditions for the release of hydrogen can be controlled. "It looks as though we might be able to come up with ways to remove the hydroxyl group (OH-) that remains attached to the aluminum clusters after they generate hydrogen so that we can reuse the aluminum clusters again and again," he said.

The team plans to continue their research with a goal of refining their new method. This research was supported by the Air Force Office of Scientific Research.

Argonne scientists prove unconventional superconductivity in new iron arsenide compounds

Inelastic neutron scattering is sensitive to sign of superconducting gap

ARGONNE, Ill. (Jan. 9, 2009) — Scientists at U.S. Department of Energy's Argonne National Laboratory used inelastic neutron scattering to show that superconductivity in a new family of iron arsenide superconductors cannot be explained by conventional theories.

"The normal techniques for revealing unconventional superconductivity don't work with these compounds," physicist Ray Osborn said. "Inelastic neutron scattering is so far the only technique that does."

Conventional superconductivity can be explained by a theory developed by Bardeen, Cooper and Schrieffer (BCS) in 1957. In BCS theory, electrons in a superconductor combine to form pairs, called Cooper pairs, which are able to move through the crystal lattice without resistance when an electric voltage is applied. Even when the voltage is removed, the current continues to flow indefinitely, the most remarkable property of superconductivity, and one that explains the keen interest in their technological potential.

Normally, electrons repel each other because of their similar charge, but, in superconductors, they coordinate with vibrations of the crystal lattice to overcome this repulsion. But scientists don't believe the vibrational mechanism in the iron arsenides is strong enough to make them superconducting. This has led theorists to propose that this superconductivity has an unconventional mechanism, perhaps like high-temperature copper-oxide superconductors. Some iron arsenides are antiferromagnetic, rather than superconducting, so magnetism rather than atomic vibrations might provide the electron glue.

In BCS superconductors, the energy gap between the superconducting and normal electronic states is constant, but in unconventional superconductors the gap varies with the direction the electrons are moving. In some directions, the gap may be zero. The puzzle is that the gap does not seem to vary with direction in the iron arsenides. Theorists have argued that, while the size of the gap shows no directional dependence in these new compounds, the sign of the gap is opposite for different electronic states. The standard techniques to measure the gap, such as photoemission, are not sensitive to this change in sign.

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LED street lights expand Ruud Lighting’s market

By THOMAS CONTENT

tcontent@journalsentinel.com
Posted: Aug. 5, 2008

Sturtevant - Energy-saving lighting that could help cities in Alaska to Australia save on the cost of electricity in street lights is creating global growth opportunities for Ruud Lighting Inc.

Ruud Lighting on Tuesday celebrated a new energy-saving street light fixture coming off the assembly line. The street light fixtures will soon be installed on several streets in Racine, Mayor Gary Becker said.

Ruud Lighting’s Beta Lighting division is seeing increased interest in LED technology because of demands to reduce costs through energy efficiency and to avoid the use of hazardous materials, such as mercury, in energy-efficient light fixtures, said Alan Ruud, company president.

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New method extracts oxygen from water with minimal energy, potentially boosting efforts to develop solar as a 24-hour energy source

July 31, 2008

Using a surprisingly simple, inexpensive technique, chemists have found a way to pull pure oxygen from water using relatively small amounts of electricity, common chemicals and a room-temperature glass of water.

Because oxygen and hydrogen are energy-rich fuels, many researchers have proposed using solar electricity to split water into those elements--a stored energy source for when the sun goes down. One of the chief obstacles to that green-energy scenario has been the difficulty of producing oxygen without large amounts of energy or a high-maintenance environment.

Now, Massachusetts Institute of Technology chemist Daniel Nocera and his postdoctoral student Matthew Kanan have discovered an efficient way to solve the oxygen problem. They announced their findings July 31, 2008, online in the journal Science.

"The discovery has enormous implications for the large scale deployment of solar since it puts us on the doorstep of a cheap and easily manufactured storage mechanism," said Nocera. "The ease of implementation means that this discovery will have legs. I have great faith in my chemistry, materials science and engineering colleagues in the community to drive this discovery hard and hopefully their work, along with our continued studies will yield viable technologies within 10 years."

While a home-based energy source using this technique could be a decade away, the breakthrough is a major step forward.

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MIT opens new 'window' on solar energy

Cost effective devices expected on market soon

Elizabeth A. Thomson, News Office
July 10, 2008

 

Imagine windows that not only provide a clear view and illuminate rooms, but also use sunlight to efficiently help power the building they are part of. MIT engineers report a new approach to harnessing the sun's energy that could allow just that.

The work, to be reported in the July 11 issue of Science, involves the creation of a novel "solar concentrator." "Light is collected over a large area [like a window] and gathered, or concentrated, at the edges," explains Marc A. Baldo, leader of the work and the Esther and Harold E. Edgerton Career Development Associate Professor of Electrical Engineering.

As a result, rather than covering a roof with expensive solar cells (the semiconductor devices that transform sunlight into electricity), the cells only need to be around the edges of a flat glass panel. In addition, the focused light increases the electrical power obtained from each solar cell "by a factor of over 40," Baldo says.

Because the system is simple to manufacture, the team believes that it could be implemented within three years--even added onto existing solar-panel systems to increase their efficiency by 50 percent for minimal additional cost. That, in turn, would substantially reduce the cost of solar electricity.

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Tiny buckyballs squeeze hydrogen like giant Jupiter

Carbon cages can hold super-dense volumes of nearly metallic hydrogen

Hydrogen could be a clean, abundant energy source, but it's difficult to store in bulk. In new research, materials scientists at Rice University have made the surprising discovery that tiny carbon capsules called buckyballs are so strong they can hold volumes of hydrogen nearly as dense as those at the center of Jupiter.

The research appears on the March 2008 cover of the American Chemical Society's journal Nano Letters.

"Based on our calculations, it appears that some buckyballs are capable of holding volumes of hydrogen so dense as to be almost metallic," said lead researcher Boris Yakobson, professor of mechanical engineering and materials science at Rice. "It appears they can hold about 8 percent of their weight in hydrogen at room temperature, which is considerably better than the federal target of 6 percent."

The Department of Energy has devoted more than $1 billion to developing technologies for hydrogen-powered automobiles, including technologies to cost-effectively store hydrogen for use in cars. Hydrogen is the lightest element in the universe, and it is very difficult to store in bulk. For hydrogen cars to be competitive with gasoline-powered cars, they need a comparable range and a reasonably compact fuel system. It's estimated that a hydrogen-powered car with a suitable range will require a storage system with densities greater than those found in pure, liquid hydrogen.

Yakobson said scientists have long argued the merits of storing hydrogen in tiny, molecular containers like buckyballs, and experiments have shown that it's possible to store small volumes of hydrogen inside buckyballs. The new research by Yakobson and former postdoctoral researchers Olga Pupysheva and Amir Farajian offers the first method of precisely calculating how much hydrogen a buckyball can hold before breaking.

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