Tag Archives: batteries

Graphene paper batteries

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Michael Mullaney’s Aug. 20, 2012 news release for Rensselaer Polytechnic Institute (RPI) highlights work on a battery made from the worlds thinnest material. From the news release,

Engineering researchers at Rensselaer Polytechnic Institute made a sheet of paper from the world’s thinnest material, graphene, and then zapped the paper with a laser or camera flash to blemish it with countless cracks, pores, and other imperfections. The result is a graphene anode material that can be charged or discharged 10 times faster than conventional graphite anodes used in today’s lithium (Li)-ion batteries.

…

“Li-ion battery technology is magnificent, but truly hampered by its limited power density and its inability to quickly accept or discharge large amounts of energy. By using our defect-engineered graphene paper in the battery architecture, I think we can help overcome this limitation,” said Koratkar, the John A. Clark and Edward T. Crossan Professor of Engineering at Rensselaer. “We believe this discovery is ripe for commercialization, and can make a significant impact on the development of new batteries and electrical systems for electric automobiles and portable electronics applications.”

Here are some more details about the graphene paper the researchers hope will replace the less efficient elements of today’s lithium-ion batteries  (from the news release),

Koratkar’s solution [to the problem of slow charging and discharge] was to use a known technique to create a large sheet of graphene oxide paper. This paper is about the thickness of a piece of everyday printer paper, and can be made nearly any size or shape. The research team then exposed some of the graphene oxide paper to a laser, and other samples of the paper were exposed to a simple flash from a digital camera. In both instances, the heat from the laser or photoflash literally caused mini-explosions throughout the paper, as the oxygen atoms in graphene oxide were violently expelled from the structure. The aftermath of this oxygen exodus was sheets of graphene pockmarked with countless cracks, pores, voids, and other blemishes. The pressure created by the escaping oxygen also prompted the graphene paper to expand five-fold in thickness, creating large voids between the individual graphene sheets.

The researchers quickly learned this damaged graphene paper performed remarkably well as an anode for a Li-ion battery. Whereas before the lithium ions slowly traversed the full length of graphene sheets to charge or discharge, the ions now used the cracks and pores as shortcuts to move quickly into or out of the graphene—greatly increasing the battery’s overall power density. Koratkar’s team demonstrated how their experimental anode material could charge or discharge 10 times faster than conventional anodes in Li-ion batteries without incurring a significant loss in its energy density. Despite the countless microscale pores, cracks, and voids that are ubiquitous throughout the structure, the graphene paper anode is remarkably robust, and continued to perform successfully even after more than 1,000 charge/discharge cycles. The high electrical conductivity of the graphene sheets also enabled efficient electron transport in the anode, which is another necessary property for high-power applications.

Here’s a citation and link for the paper (which is behind a paywall),

Photothermally Reduced Graphene as High-Power Anodes for Lithium-Ion Batteries by Rahul Mukherjee, Abhay Varghese Thomas, Ajay Krishnamurthy, and Nikhil Koratkar in ACS Nano, Article ASAP DOI: 10.1021/nn303145j Publication Date (Web): August 11, 2012

If the researchers are successful, electric cars could become 100% battery-run.

Paint your own battery

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Reserchers at Pulickel Ajayan’s laboratory at Rice University have developed a paintable battery (here’s the video),

The June 28, 2012 Rice University news release offers more details about how the paintable battery was achieved,

Lead author [research paper appeared in Nature’s online, open-access journal Scientific Reports] Neelam Singh, a Rice graduate student, and her team spent painstaking hours formulating, mixing and testing paints for each of the five layered components – two current collectors, a cathode, an anode and a polymer separator in the middle.

The materials were airbrushed onto ceramic bathroom tiles, flexible polymers, glass, stainless steel and even a beer stein to see how well they would bond with each substrate.

In the first experiment, nine bathroom tile-based batteries were connected in parallel. One was topped with a solar cell that converted power from a white laboratory light. When fully charged by both the solar panel and house current, the batteries alone powered a set of light-emitting diodes that spelled out “RICE” for six hours; the batteries provided a steady 2.4 volts.

The researchers reported that the hand-painted batteries were remarkably consistent in their capacities, within plus or minus 10 percent of the target. They were also put through 60 charge-discharge cycles with only a very small drop in capacity, Singh said.

You can also find the details and more images at the June 28, 2012 news item on physorg.com,

Each layer is an optimized stew. The first, the positive current collector, is a mixture of purified single-wall carbon nanotubes with carbon black particles dispersed in N-methylpyrrolidone. The second is the cathode, which contains lithium cobalt oxide, carbon and ultrafine graphite (UFG) powder in a binder solution. The third is the polymer separator paint of Kynar Flex resin, PMMA and silicon dioxide dispersed in a solvent mixture. The fourth, the anode, is a mixture of lithium titanium oxide and UFG in a binder, and the final layer is the negative current collector, a commercially available conductive copper paint, diluted with ethanol.

“The hardest part was achieving mechanical stability, and the separator played a critical role,” Singh said. “We found that the nanotube and the cathode layers were sticking very well, but if the separator was not mechanically stable, they would peel off the substrate. Adding PMMA gave the right adhesion to the separator.” Once painted, the tiles and other items were infused with the electrolyte and then heat-sealed and charged.

Singh said the batteries were easily charged with a small solar cell. She foresees the possibility of integrating paintable batteries with recently reported paintable solar cells to create an energy-harvesting combination that would be hard to beat. As good as the hand-painted batteries are, she said, scaling up with modern methods will improve them by leaps and bounds. “Spray painting is already an industrial process, so it would be very easy to incorporate this into industry,” Singh said.

Ajayan’s lab must be a very exciting place to work given the research that has been published in 2012 so far (my Serendipity and coaxial cables post; my Nanosponges clean up spilled oil and release the oil for future use post; my Good heat, bad heat, and cooling oils post).

And to give credit to everyone: co-authors of the paper are graduate students Charudatta Galande and Akshay Mathkar, alumna Wei Gao, now a postdoctoral researcher at Los Alamos National Laboratory, and research scientist Arava Leela Mohana Reddy, all of Rice; Rice Quantum Institute intern Andrea Miranda; and Alexandru Vlad, a former research associate at Rice, now a postdoctoral researcher at the Université Catholique de Louvain, Belgium.

US soldiers get batteries woven into their clothes

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Last time I wrote about soldiers, equipment, and energy-efficiency (April 5, 2012 posting) the soldiers in question were British. Today’s posting focuses on US soldiers. From the May 7, 2012 news item on Nanowerk,

U.S. soldiers are increasingly weighed down by batteries to power weapons, detection devices and communications equipment. So the Army Research Laboratory has awarded a University of Utah-led consortium almost $15 million to use computer simulations to help design materials for lighter-weight, energy efficient devices and batteries.

“We want to help the Army make advances in fundamental research that will lead to better materials to help our soldiers in the field,” says computing Professor Martin Berzins, principal investigator among five University of Utah faculty members who will work on the project. “One of Utah’s main contributions will be the batteries.”

Of the five-year Army grant of $14,898,000, the University of Utah will retain $4.2 million for research plus additional administrative costs. The remainder will go to members of the consortium led by the University of Utah, including Boston University, Rensselaer Polytechnic Institute, Pennsylvania State University, Harvard University, Brown University, the University of California, Davis, and the Polytechnic University of Turin, Italy.

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The new research effort is based on the idea that by using powerful computers to simulate the behavior of materials on multiple scales – from the atomic and molecular nanoscale to the large or “bulk” scale – new, lighter, more energy efficient power supplies and materials can be designed and developed. Improving existing materials also is a goal.

“We want to model everything from the nanoscale to the soldier scale,” Berzins says. “It’s virtual design, in some sense.”

“Today’s soldier enters the battle space with an amazing array of advanced electronic materials devices and systems,” the University of Utah said in its grant proposal. “The soldier of the future will rely even more heavily on electronic weaponry, detection devices, advanced communications systems and protection systems. Currently, a typical infantry soldier might carry up to 35 pounds of batteries in order to power these systems, and it is clear that the energy and power requirements for future soldiers will be much greater.” [emphasis mine]

“These requirements have a dramatic adverse effect on the survivability and lethality of the soldier by reducing mobility as well as the amount of weaponry, sensors, communication equipment and armor that the soldier can carry. Hence, the Army’s desire for greater lethality and survivability of its men and women in the field is fundamentally tied to the development of devices and systems with increased energy efficiency as well as dramatic improvement in the energy and power density of [battery] storage and delivery systems.”

Up to 35 lbs. of batteries? I’m trying to imagine what the rest of the equipment would weigh. In any event, they seem to be more interested in adding to the weaponry than reducing weight. At least, that’s how I understand “greater *lethality.” Nice of them to mention greater survivability too.

The British project is more modest, they are weaving e-textiles that harvest energy allowing British soldiers to carry fewer batteries. I believe field trials were scheduled for May 2012.

* Correction: leathility changed to lethality on July 31, 2013.

Bacteria and biobatteries

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It’s more a possibility at the moment than anything else but researchers at Concordia University in Montréal, Canada have found a way to make an enzyme behave more like a battery. From the April 19, 2012 news item on Nanowerk,

Concordia Associate Professor László Kálmán — along with his colleagues in the Department of Physics, graduate students Sasmit Deshmukh and Kai Tang — has been working with an enzyme found in bacteria that is crucial for capturing solar energy. Light induces a charge separation in the enzyme, causing one end to become negatively charged and the other positively charged, much like in a battery.

In nature, the energy created is used immediately, but Kálmán says that to store that electrical potential, he and his colleagues had to find a way to keep the enzyme in a charge-separated state for a longer period of time.

“We had to create a situation where the charges don’t want to or are not allowed to go back, and that’s what we did in this study,” he says.

Kálmán and his colleagues showed that by adding different molecules, they were able to alter the shape of the enzyme and, thus, extend the lifespan of its electrical potential.

In the April 17, 2012 news item written by Luciana Gravotta for Concordia University, Kálmán provides an explanation of why the researchers were changing the enzyme’s shape,

In its natural configuration, the enzyme is perfectly embedded in the cell’s outer layer, known as the lipid membrane. The enzyme’s structure allows it to quickly recombine the charges and recover from a charge-separated state.

However, when different lipid molecules make up the membrane, as in Kálmán’s experiments, there is a mismatch between the shape of the membrane and the enzyme embedded within it. Both the enzyme and the membrane end up changing their shapes to find a good fit. The changes make it more difficult for the enzyme to recombine the charges, thereby allowing the electrical potential to last much longer.

“What we’re doing is similar to placing a race car on snow-covered streets,” says Kálmán. The surrounding conditions prevent the race car from performing as it would on a racetrack, just like the different lipids prevent the enzyme from recombining the charges as efficiently as it does under normal circumstances.

Apparently the researchers are hoping to eventually create biocompatible batteries with enzymes and other biological molecules replacing traditional batteries that contain toxic metals.

Textiles used as batteries at UC Berkeley; University of Calgary, quantum entanglement and building blocks; Raymor Industries has a nano problem with its shareholders?

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There seems to be a race to get our clothes electrified so we can become portable recharging devices. From the news item on Azonano,

In research that gives literal meaning to the term “power suit,” University of California, Berkeley, engineers have created energy-scavenging nanofibers that could one day be woven into clothing and textiles.

These nano-sized generators have “piezoelectric” properties that allow them to convert into electricity the energy created through mechanical stress, stretches and twists.

“This technology could eventually lead to wearable ‘smart clothes’ that can power hand-held electronics through ordinary body movements,” said Liwei Lin, UC Berkeley professor of mechanical engineering and head of the international research team that developed the fiber nanogenerators.

This announcement is on the heels of a similar announcement (noted in my posting of Jan.22.10 here)  from researchers at the University of Stanford in California.

Meanwhile, scientists at the University of Calgary are playing with construction toys (they use the lego metaphor, which seems quite popular right now). From the news release on the University of Calgary website (thanks to Azonano where I first found notice of the item),

While many of us enjoyed constructing little houses out of toy bricks, this task is much more difficult if the bricks are elementary particles. It is even harder if these are particles of light—photons—which can only exist while flying at an incredible speed and vanish if they touch anything.

Yet a team at the University of Calgary has accomplished exactly that. By manipulating a mysterious quantum property of light known as entanglement, they are able to mount up to two photons on top of one another to construct a variety of quantum states of light—that is, build two-story quantum toy houses of any style and architecture.

The research has just (yesterday, Feb.14.10) been published in Nature Photonics. You can read the abstract (here after you scroll down) but the rest of the article is behind a paywall.

I found something rather odd this morning about Raymor Industries. It’s a Canadian nanotechnology company (their products are based on single-walled carbon nanotubes) traded on the TSX that is currently experiencing difficulty with, at least some, shareholders. From the item on PRNewsWire,

RAYMOR INDUSTRIES INC. (TSX Venture RAR, RAYRF) is a leading Canadian developer of high technology and a producer of advanced materials and nanomaterials for high value-added applications. Raymor holds the exclusive rights to more than 20 patents throughout the world, with other patents pending. Shareholders have formed a group to fight to protect our shareholder rights and prevent the current board of directors from delisting and the eliminating the common shares of the corporation.  The group is called The Raymor Investors Special Action Group.  The group is sending out this communication to get the attention of the 8000 shareholders and advise them that an appeal to the recent January 27, 2010 court ruling has been launched and is underway.  A strong and reasonable chance exists that the appeal can be won.

If you’re curious about the company and its products, you can read more here at their website, although they offer no additional information about the contretemps.