Nanotechnology Brings First “Water – in – Salt” Batteries

Lab on chip (LOC)

The latest in nanotechnology has brought the world the first ‘water-in-salt” battery, which fuses water, salt and Lithium to make batteries as potent as regular Lithium-ion batteries. The team, from the U.S. Army Research Laboratory and the University of Maryland, have devised an energy source that does not come with the fire or chemical hazard that comes in regular Lithium-ion batteries.

Nanotechnology Makes Us Greener

The full report is published in the journal Science, and it constitutes a major breakthrough in aqueous Lithium-ion battery technology and nanotechnology. This ‘salt-in-water’ battery is twice as potent as any other aqueous battery developed, and has the longevity of the traditional Lithium-ion battery

According to the team, their nanotechnology research can be applied to large scale proportions, like electric vehicle technology or energy harvest systems and medical devices such as pacemakers or other electrical powered valves. Their research shows that aqueous batteries have the ability to power up to 2.3 Volts, meaning that they could replace regular Lithium-ion. We already use this technology in the digital world, but it could be blown up to much larger proportions.


This Breakthrough is the Product of Solid Electrolyte Interphase

The researchers achieved this kind of voltage by taking a type of water based electrolyte with high concentrations of a specific Lithium salt. This changed the chemistry of the battery and created a film around the anode electrode, something that had never happened in a water-based battery before. This kind of protective film is known as a Solid Electrolyte Interphase, which had only happened in non-aqueous electrolytes before.

These batteries were proven to be more stable than other aqueous batteries, achieving both cycling stability and high voltage without depending on each other or at the expanse of energy density.

We Don’t Know How Practical this Nanotechnology Is

Though the applications for this breakthrough are incredibly important, the scientific community isn’t yet aware of how realistically practical the discovery is. This breakthrough mostly opens up a door in nanotechnology that hadn’t ever been seen before, and further research and development can bring it to its full potential.

MIT: Forget Graphene and Carbon Nanotubes, Get Ready for Diamond Nanothread

MIT 111915 Diamond%20nanothread

The discovery of a stable form of one-dimensional diamond has scientists racing to understand its properties. The first signs are that diamond nanothread will be more versatile than anyone expected. What will this mean?

Hardly a week goes by without somebody proclaiming a new application for graphene, the form of carbon that occurs in single sheets with chicken wire-like structure (see “Research Hints at Graphene’s Photovoltaic Potential”). Roll a graphene sheet into a tube and it forms a carbon nanotube, another wonder material with numerous applications. And wrap it further into a ball and, with a small rearrangement of bonds, it forms buckyballs.

Now there is a new kid on the carbon block. Last month, a team at Pennsylvania State University and elsewhere announced they had created another type of carbon that takes the form of a one-dimensional diamond crystal capped with hydrogen. They call this new material diamond nanothread.

That caused a flurry of excitement and raised some interesting questions. Materials scientists are fascinated by the potential properties of a diamond nanothread and its applications. But one fear is that such a thread would be so brittle that it would shatter like glass under any kind of load, a property that would severely limit its use.

Today, we get some new insight into diamond nanothreads thanks to the work of Haifei Zhan at Queensland University of Technology in Australia and a few pals. These guys have modeled the threads using large-scale molecular dynamics simulations. And they conclude that the material could be more versatile than anyone thought. There are tentative signs that diamond nanothread could be a new a wonder material in its own right.

The Penn State team manufactured the nanothread from benzene molecules, simple rings of carbon atoms. It’s not hard to see how a stack of these could bond in a way that forms a thread.

And that’s exactly what the Penn State team did. They stacked the molecules into a line, placed it under pressure so that the molecules polymerized and, voila, created a diamond nanothread.

That sounds simple in theory but the complexity arises from the way the carbon atoms can bond. Various configurations are possible, and the question that Zhan and co investigate is how the properties of the thread depend on these arrangements.

In particular, Zhan and co look at the two most common configurations. The first is straightforward polymerized benzene—a stack of these rings bonded together. This is a rigid molecule that becomes increasingly brittle as it gets longer. Constructing anything complex with long sections of poly-benzene would be like trying to sew with like uncooked spaghetti.

But there is another configuration of carbon atoms known as Stone-Wales defects, and these are much more malleable. Indeed, the Stone-Wales defects act like hinges connecting sections of poly-benzene.

Zhan and co simulate how the properties of the nanothread vary as the density of these defects increases. And they conclude that when the density crosses a particular threshold, the thread suddenly changes from brittle to entirely flexible—rather like the difference between uncooked and cooked spaghetti.

That’s an interesting result. It implies that the property of the nanothread can be tuned simply by controlling the density of Stone-Wales defects along its length. So some parts of the thread can be made rigid, while others are entirely flexible.

What of potential applications? “Its highly tunable ductility together with its ultra-light density and high Young’s modulus makes diamond nanothread ideal for the creation of extremely strong three-dimensional nano-architectures,” say Zhan and co.

Of course, this work is just a simulation. There are almost certainly going to be differences between its predictions and the behavior of diamond nanothreads in the real world. So the next step will be for materials scientists to create some nanothread construction kits and start measuring this material’s properties for real.

Given the huge interest in carbon architecture and the vast sums of money being poured into this area—the European Union alone has a €1 billion research project focused purely on graphene—it surely won’t be long before we see diamond nanothreads in the flesh and some of the extraordinary applications that it should make possible.

Ref: From Brittle to Ductile: A Structure Dependent Ductility of Diamond Nanothread


Graphene’s stabilizling influence on Supercapacitors

Graphene Supercapacitors 111815 id41889Supercapacitors can be charged and discharged tens of thousands of times, but their relatively low energy density compared to conventional batteries limits their application for energy storage. Now, A*STAR researchers have developed an ‘asymmetric’ supercapacitor based on metal nitrides and graphene that could be a viable energy storage solution (“All Metal Nitrides Solid-State Asymmetric Supercapacitors”).
asymmetric supercapacitor
llustration of the asymmetric supercapacitor, consisting of vertically aligned graphene nanosheets coated with iron nitride and titanium nitride as the anode and cathode, respectively. (©WILEY-VCH Verlag)

A supercapacitor’s viability is largely determined by the materials of which its anodes and cathodes are comprised. These electrodes must have a high surface area per unit weight, high electrical conductivity and capacitance and be physically robust so they do not degrade during operation in liquid or hostile environments.

Unlike traditional supercapacitors, which use the same material for both electrodes, the anode and cathode in an asymmetric supercapacitor are made up of different materials. Scientists initially used metal oxides as asymmetric supercapacitor electrodes, but, as metal oxides do not have particularly high electrical conductivities and become unstable over long operating cycles, it was clear that a better alternative was needed.
Metal nitrides such as titanium nitride, which offer both high conductivity and capacitance, are a promising alternative, but they tend to oxidize in watery environments that limits their lifetime as an electrode. A solution to this is to combine them with more stable materials.
Hui Huang from A*STAR’s Singapore Institute of Manufacturing Technology and his colleagues from Nanyang Technological University and Jinan University, China, have fabricated asymmetric supercapacitors which incorporate metal nitride electrodes with stacked sheets of graphene.
To get the maximum benefit from the graphene surface, the team used a precise method for creating thin-films, a process known as atomic layer deposition, to grow two different materials on vertically aligned graphene nanosheets: titanium nitride for their supercapacitor’s cathode and iron nitride for the anode. The cathode and anode were then heated to 800 and 600 degrees Celsius respectively, and allowed to slowly cool. The two electrodes were then separated in the asymmetric supercapacitor by a solid-state electrolyte, which prevented the oxidization of the metal nitrides.
The researchers tested their supercapacitor devices and showed they could cycle 20,000 times and exhibited both high capacitance and high power density. “These improvements are due to the ultra-high surface area of the vertically aligned graphene substrate and the atomic layer deposition method that enables full use of it,” says Huang. “In future research, we want to enlarge the working-voltage of the device to increase energy density further still,” says Huang.
Source: A*STAR

Read more: Graphene’s stabilizling influence on supercapacitors

Ultrasensitive sensors: Boron-doped Graphene

Graphene Sensors 111715 1-ultrasensiti

Ultrasensitive gas sensors based on the infusion of boron atoms into graphene—a tightly bound matrix of carbon atoms—may soon be possible, according to an international team of researchers from six countries.

Graphene is known for its remarkable strength and ability to transport electrons at high speed, but it is also a highly sensitive gas sensor. With the addition of atoms, the boron graphene sensors were able to detect noxious gas molecules at extremely low concentrations, parts per billion in the case of and parts per million for ammonia, the two gases tested to date. This translates to a 27 times greater sensitivity to nitrogen oxides and 10,000 times greater sensitivity to ammonia compared to pristine graphene. The researchers believe these results, reported today (Nov. 2) in the Proceedings of the National Academy of Sciences, will open a path to high-performance sensors that can detect trace amounts of many other molecules.

“This is a project that we have been pursuing for the past four years, ” said Mauricio Terrones, professor of physics, chemistry and materials science at Penn State. “We were previously able to dope graphene with atoms of nitrogen, but boron proved to be much more difficult. Once we were able to synthesize what we believed to be boron graphene, we collaborated with experts in the United States and around the world to confirm our research and test the properties of our material.”

Both boron and nitrogen lie next to carbon on the periodic table, making their substitution feasible. But boron compounds are very air sensitive and decompose rapidly when exposed to the atmosphere. One-centimeter-square sheets were synthesized at Penn State in a one-of-a-kind bubbler-assisted chemical vapor deposition system. The result was large-area, high-quality boron-doped graphene sheets.

Once fabricated, the researchers sent boron graphene samples to researchers at the Honda Research Institute USA Inc., Columbus, Ohio, who tested the samples against their own highly sensitive . Konstantin Novoselov’s lab at the University of Manchester, UK, studied the transport mechanism of the sensors. Novoselov was the 2010 Nobel laureate in physics. Theory collaborators in the U.S. and Belgium matched the scanning tunneling microscopy images to experimental images, confirmed the presence of the in the graphene lattice and their effect when interacting with ammonia or nitrogen oxide molecules. Collaborators in Japan and China also contributed to the research.

“This multidisciplinary research paves a new avenue for further exploration of ultrasensitive gas sensors,” said Avetik Harutyunyan, chief scientist and project leader at Honda Research Institute USA Inc. “Our approach combines novel nanomaterials with continuous ultraviolet light radiation in the sensor design that have been developed in our laboratory by lead researcher Dr. Gugang Chen in the last five years. We believe that further development of this technology may break the parts per quadrillion level of detection limit, which is up to six orders of magnitude better sensitivity than current state-of-the-art sensors.”

These sensors can be used for labs and industries that use ammonia, a highly corrosive health hazard, or to detect nitrogen oxides, a dangerous atmospheric pollutant emitted from automobile tailpipes. In addition to detecting toxic or flammable gases, theoretical work indicates that boron-doped graphene could lead to improved lithium-ion batteries and field-effect transistors, the authors report.

Explore further: Study opens graphene band-gap

More information: Ultrasensitive gas detection of large-area boron-doped graphene, PNAS,



Research at the Univeristy of Exeter boosts graphene revolution

White GRaphene 07-20-15_BORON-1-rnx250Pioneering new research by the Univ. of Exeter could pave the way for miniaturized optical circuits and increased internet speeds, by helping accelerate the ‘graphene revolution’.

Physicists from the Univ. of Exeter in collaboration with the ICFO Institute in Barcelona have used a ground-breaking new technique to trap light at the surface of the wonder material graphene using only pulses of laser light.

Crucially, the team of scientists have also been able to steer this trapped light across the surface of the graphene, without the need for any nanoscale devices. This dual breakthrough opens up a host of opportunities for advances in pivotal electronic products, such as sensors and miniaturized integrated circuits.

The new research features in the latest online edition of the respected scientific journal, Nature Physics.

Dr. Tom Constant, lead author on the paper and part of Exeter’s Physics and Astronomy Department said: ” This new research has the potential to give us invaluable insight into the wonder material and how it interacts with light. A more immediate commercial application could be a simple device that could easily scan a piece of graphene and tell you some key properties like conductivity, resistance and purity .”

Dr. Constant and his colleagues used pulses of light to be able to trap the light on the surface of commercially-available graphene. When trapped, the light converts into a quasi-particle called a ‘surface plasmon’, a mixture of both light and the graphene’s electrons.

Additionally, the team have demonstrated the first example of being able to steer the plasmons around the surface of the graphene, without the need to manufacture complicated nanoscale systems. The ability both to trap light at a surface, and direct it easily, opens up new opportunities for a number of electronic-based devices, as well as help to bridge the gap between the electronics and light.

Dr. Constant said: “Computers than can use light as part of their infrastructure have the potential to show significant improvement. Any advance that reveals more about light’s interaction with graphene-based electronics will surely benefit the computers or smartphones of the future.”

Source: Univ. of Exeter

MIT: A “Shocking” New Way to “Desalinate” – No Membranes and Less Energy

MIT Desal Shock 111315 bt1511_MIT-fracking-pondAs the availability of clean, potable water becomes an increasingly urgent issue in many parts of the world, researchers are searching for new ways to treat salty, brackish or contaminated water to make it usable. Now a team at MIT has come up with an innovative approach that, unlike most traditional desalination systems, does not separate ions or water molecules with filters, which can become clogged, or boiling, which consumes great amounts of energy.

Instead, the system uses an electrically driven shockwave within a stream of flowing water, which pushes salty water to one side of the flow and fresh water to the other, allowing easy separation of the two streams. The new approach is described in the journal Environmental Science and Technology Letters, in a paper by professor of chemical engineering and mathematics Martin Bazant, graduate student Sven Schlumpberger, undergraduate Nancy Lu, and former postdoc Matthew Suss.

This approach is “a fundamentally new and different separation system,” Bazant says. And unlike most other approaches to desalination or water purification, he adds, this one performs a “membrane-less separation” of ions and particles.

Membranes in traditional desalination systems, such as those that use reverse osmosis or electrodialysis, are “selective barriers,” Bazant explains: They allow molecules of water to pass through, but block the larger sodium and chlorine atoms of salt. Compared to conventional electrodialysis, “This process looks similar, but it’s fundamentally different,” he says.

In the new process, called shock electrodialysis, water flows through a porous material —in this case, made of tiny glass particles, called a frit — with membranes or electrodes sandwiching the porous material on each side. When an electric current flows through the system, the salty water divides into regions where the salt concentration is either depleted or enriched. When that current is increased to a certain point, it generates a shockwave between these two zones, sharply dividing the streams and allowing the fresh and salty regions to be separated by a simple physical barrier at the center of the flow.

“It generates a very strong gradient,” Bazant says.

Even though the system can use membranes on each side of the porous material, Bazant explains, the water flows across those membranes, not through them. That means they are not as vulnerable to fouling — a buildup of filtered material — or to degradation due to water pressure, as happens with conventional membrane-based desalination, including conventional electrodialysis. “The salt doesn’t have to push through something,” Bazant says. The charged salt particles, or ions, “just move to one side,” he says.

The underlying phenomenon of generating a shockwave of salt concentration was discovered a few years ago by the group of Juan Santiago at Stanford University. But that finding, which involved experiments with a tiny microfluidic device and no flowing water, was not used to remove salt from the water, says Bazant, who is currently on sabbatical at Stanford.

The new system, by contrast, is a continuous process, using water flowing through cheap porous media, that should be relatively easy to scale up for desalination or water purification. “The breakthrough here is the engineering [of a practical system],” Bazant says.

One possible application would be in cleaning the vast amounts of wastewater generated by hydraulic fracturing, or fracking. This contaminated water tends to be salty, sometimes with trace amounts of toxic ions, so finding a practical and inexpensive way of cleaning it would be highly desirable. This system not only removes salt, but also a wide variety of other contaminants — and because of the electrical current passing through, it may also sterilize the stream. “The electric fields are pretty high, so we may be able to kill the bacteria,” Schlumpberger says.

The research produced both a laboratory demonstration of the process in action and a theoretical analysis that explains why the process works, Bazant says. The next step is to design a scaled-up system that could go through practical testing.

Initially at least, this process would not be competitive with methods such as reverse osmosis for large-scale seawater desalination. But it could find other uses in the cleanup of contaminated water, Schlumpberger says.

Unlike some other approaches to desalination, he adds, this one requires little infrastructure, so it might be useful for portable systems for use in remote locations, or for emergencies where water supplies are disrupted by storms or earthquakes.

Maarten Biesheuvel, a principal scientist at the Netherlands Water Technology Institute who was not involved in this research, says the work “is of very high significance to the field of water desalination. It opens up a whole range of new possibilities for water desalination, both for seawater and brackish water resources, such as groundwater.”

Biesheuvel adds that this team “shows a radically new design where within one and the same channel ions are separated between different regions. … I expect that this discovery will become a big ‘hit’ in the academic field. … It will be interesting to see whether the upscaling of this technology, from a single cell to a stack of thousands of cells, can be achieved without undue problems.”

The research was supported by the MIT Energy Initiative, Weatherford International, the USA-Israel Binational Science Foundation, and the SUTD-MIT Graduate Fellows Program.

Source: Massachusetts Institute of Technology


Nanopores could be the Solution for Taking the “Salt” out of Seawater

Nanoposres Seawater id41830University of Illinois engineers have found an energy-efficient material for removing salt from seawater that could provide a rebuttal to poet Samuel Taylor Coleridge’s lament, “Water, water, every where, nor any drop to drink.”

The material, a nanometer-thick sheet of molybdenum disulfide (MoS2) riddled with tiny holes called nanopores, is specially designed to let high volumes of water through but keep salt and other contaminates out, a process called desalination. In a study published in the journal Nature Communications (“Water desalination with a single-layer MoS2 nanopore”), the Illinois team modeled various thin-film membranes and found that MoS2 showed the greatest efficiency, filtering through up to 70 percent more water than graphene membranes.
nanopore water filter
A computer model of a nanopore in a single-layer sheet of MoS2 shows that high volumes of water can pass through the pore using less pressure than standard plastic membranes. Salt water is shown on the left, fresh water on the right. (Image: Mohammad Heiranian)
“Even though we have a lot of water on this planet, there is very little that is drinkable,” said study leader Narayana Aluru, a U. of I. professor of mechanical science and engineering. “If we could find a low-cost, efficient way to purify sea water, we would be making good strides in solving the water crisis.
“Finding materials for efficient desalination has been a big issue, and I think this work lays the foundation for next-generation materials. These materials are efficient in terms of energy usage and fouling, which are issues that have plagued desalination technology for a long time,” said Aluru, who also is affiliated with the Beckman Institute for Advanced Science and Technology at the U. of I.
Most available desalination technologies rely on a process called reverse osmosis to push seawater through a thin plastic membrane to make fresh water. The membrane has holes in it small enough to not let salt or dirt through, but large enough to let water through. They are very good at filtering out salt, but yield only a trickle of fresh water. Although thin to the eye, these membranes are still relatively thick for filtering on the molecular level, so a lot of pressure has to be applied to push the water through.
“Reverse osmosis is a very expensive process,” Aluru said. “It’s very energy intensive. A lot of power is required to do this process, and it’s not very efficient. In addition, the membranes fail because of clogging. So we’d like to make it cheaper and make the membranes more efficient so they don’t fail as often. We also don’t want to have to use a lot of pressure to get a high flow rate of water.”
One way to dramatically increase the water flow is to make the membrane thinner, since the required force is proportional to the membrane thickness. Researchers have been looking at nanometer-thin membranes such as graphene. However, graphene presents its own challenges in the way it interacts with water.
Aluru’s group has previously studied MoS2 nanopores as a platform for DNA sequencing and decided to explore its properties for water desalination. Using the Blue Waters supercomputer at the National Center for Supercomputing Applications at the U. of I., they found that a single-layer sheet of MoS2 outperformed its competitors thanks to a combination of thinness, pore geometry and chemical properties.
A MoS2 molecule has one molybdenum atom sandwiched between two sulfur atoms. A sheet of MoS2, then, has sulfur coating either side with the molybdenum in the center. The researchers found that creating a pore in the sheet that left an exposed ring of molybdenum around the center of the pore created a nozzle-like shape that drew water through the pore.
“MoS2 has inherent advantages in that the molybdenum in the center attracts water, then the sulfur on the other side pushes it away, so we have much higher rate of water going through the pore,” said graduate student Mohammad Heiranian, the first author of the study. “It’s inherent in the chemistry of MoS2 and the geometry of the pore, so we don’t have to functionalize the pore, which is a very complex process with graphene.”
In addition to the chemical properties, the single-layer sheets of MoS2 have the advantages of thinness, requiring much less energy, which in turn dramatically reduces operating costs. MoS2 also is a robust material, so even such a thin sheet is able to withstand the necessary pressures and water volumes.
The Illinois researchers are establishing collaborations to experimentally test MoS2 for water desalination and to test its rate of fouling, or clogging of the pores, a major problem for plastic membranes. MoS2 is a relatively new material, but the researchers believe that manufacturing techniques will improve as its high performance becomes more sought-after for various applications.
“Nanotechnology could play a great role in reducing the cost of desalination plants and making them energy efficient,” said Amir Barati Farimani, who worked on the study as a graduate student at Illinois and is now a postdoctoral fellow at Stanford University. “I’m in California now, and there’s a lot of talk about the drought and how to tackle it. I’m very hopeful that this work can help the designers of desalination plants. This type of thin membrane can increase return on investment because they are much more energy efficient.”
Source: University of Illinois at Urbana-Champaign