Strong current of energy runs through MIT: Robust community focused on fueling the world’s future +Video


MIT-Energy-Past-Future-borders-01 small_0Top row (l-r): Tata Center spinoff Khethworks develops affordable irrigation for the developing world; students discuss utility research in Washington; thin, lightweight solar cell developed by Professor Vladimir Bulović and team. Bottom row (l-r): MIT’s record-setting Alcator tokamak fusion research reactor; a researcher in the MIT Energy Laboratory’s Combustion Research Facility; Professor Kripa Varanasi, whose research on slippery surfaces has led to a spinoff co-founded with Associate Provost Karen Gleason.

Photos: Tata Center for Technology and Design, MITEI, Joel Jean and Anna Osherov, Bob Mumgaard/PSFC, Energy Laboratory Archives, Bryce Vickmark

Research, education, and student activities help create a robust community focused on fueling the world’s future.

On any given day at MIT, undergraduates design hydro-powered desalination systems, graduate students test alternative fuels, and professors work to tap the huge energy-generating potential of nuclear fusion, biomaterials, and more. While some MIT researchers are modeling the impacts of policy on energy markets, others are experimenting with electrochemical forms of energy storage.

This is the robust energy community at MIT. Developed over the past 10 years with the guidance and support of the MIT Energy Initiative (MITEI) — and with roots extending back into the early days of the Institute — it has engaged more than 300 faculty members and spans more than 900 research projects across all five schools.

In addition, MIT offers a multidisciplinary energy minor and myriad energy-related events and activities throughout the year. Together, these efforts ensure that students who arrive on campus with an interest in energy have free rein to pursue their ambitions.

Opportunities for students

“The MIT energy ecosystem is an incredible system, and it’s built from the ground up,” says Robert C. Armstrong, a professor of chemical engineering and the director of MITEI, which is overseen at the Institute level by Vice President for Research Maria Zuber. “It begins with extensive student involvement in energy.” MITnano_ 042216 InfCorrTerraceView_label (1)

Opportunities begin the moment undergraduates arrive on campus, with a freshman pre-orientation program offered through MITEI that includes such hands-on activities as building motors and visiting the Institute’s nuclear research reactor.

“I got accepted into the pre-orientation program and from there, I was just hooked. I learned about solar technology, wind technology, different types of alternative fuels, bio fuels, even wave power,” says graduate student Priyanka Chatterjee ’15, who minored in energy studies and majored in mechanical and ocean engineering.

Those who choose the minor take a core set of subjects encompassing energy science, technology, and social science. Those interested in a deep dive into research can participate in the Energy Undergraduate Research Opportunities Program (UROP), which provides full-time summer positions. UROP students are mentored by graduate students and postdocs, many of them members of the Society of Energy Fellows, who are also conducting their own energy research at MIT.

For extracurricular activities, students can join the MIT Energy Club, which is among the largest student-run organizations at MIT with more than 5,000 members. They can also compete for the MIT Clean Energy Prize, a student competition that awards more than $200,000 each year for energy innovation. And there are many other opportunities.

The Tata Center for Technology and Design, now in its sixth year, extends MIT’s reach abroad. It supports 65 graduate students every year who conduct research central to improving life in developing countries — including lowering costs of rural electrification and using solar energy in novel ways.

Students have other opportunities to conduct and share energy research internationally as well.

“Over the years, MITEI has made it possible for several of the students I’ve advised to engage more directly in global energy and climate policy negotiations,” says Valerie Karplus, an assistant professor of global economics and management. “In 2015, I joined them at the Paris climate conference, which was a tremendous educational and outreach experience for all of us.”

Holistic problem-solving

“What is important is to provide our students a holistic understanding of the energy challenges,” says MIT Associate Dean for Innovation Vladimir Bulović.

Adds Karplus: “There’s been an evolution in thinking from ‘How do we build a better mousetrap?’ to ‘How do we bring about change in society at a system level?’”

This kind of thinking is at the root of MIT’s multidisciplinary approach to addressing the global energy challenge — and it has been since MITEI was conceived and launched by then-MIT President Susan Hockfield, a professor of neuroscience. While energy research has been part of the Institute since its founding (MIT’s first president, William Barton Rogers, famously collapsed and died after uttering the words “bituminous coal” at the 1882 commencement), the concerted effort to connect researchers across the five schools for collaborative projects is a more recent development.

“The objective of MITEI was really to solve the big energy problems, which we feel needs all of the schools’ and departments’ contributions,” says Ernest J. Moniz, a professor emeritus of physics and special advisor to MIT’s president. Moniz was the founding director of MITEI before serving as U.S. Secretary of Energy during President Obama’s administration.

Hockfield says great technology by itself “can’t go anywhere without great policy.”

“It’s the economics, it’s the sociology, it’s the science and the engineering, it’s the architecture — it’s all of the pieces of MIT that had to come together if we were going to develop really impactful sustainable energy solutions,” she says.

This multidisciplinary approach is evident in much of MIT’s energy research — notably the series of comprehensive studies MITEI has conducted on such topics as the future of solar energy, natural gas, the electric grid, and more.

“To make a better world, it’s essential that we figure out how to take what we’ve learned at MIT in energy and get that out into the world,” Armstrong says.

Fostering collaborations

MITEI’s eight low-carbon energy research centers — focused on a range of topics from materials design to solar generation to carbon capture and storage — similarly address challenges on multiple technology and policy fronts. These centers are a core component of MIT’s five-year Plan for Action on Climate Change, announced by President L. Rafael Reif in October 2015. The centers employ a strategy that has been fundamental to MIT’s energy work since the founding of MITEI: broad, sustained collaboration with stakeholders from industry, government, and the philanthropic and non-governmental organization communities.

“It’s one thing to do research that’s interesting in a laboratory. It’s something very different to take that laboratory discovery into the world and deliver practical applications,” Hockfield says. “Our collaboration with industry allowed us to do that with a kind of alacrity that we could never have done on our own.”

For example, MITEI’s members have supported more than 160 energy-focused research projects, representing $21.4 million in funding over the past nine years, through the Seed Fund Program. Projects have led to follow-on federal and industry funding, startup companies, and pilot plants for solar desalinization systems in India and Gaza, among other outcomes.

What has MIT’s energy community as a whole accomplished over the past decade? Hockfield says it’s raised the visibility of the world’s energy problems, contributed solutions — both technical and sociopolitical — and provided “an army of young people” to lead the way to a sustainable energy future.

“I couldn’t be prouder of what MIT has contributed,” she says. “We are in the midst of a reinvention of how we make energy and how we use energy. And we will develop sustainable energy practices for a larger population, a wealthier population, and a healthier planet.”

 

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Grid Batteries Are Poised to Become Cheaper Than Natural-Gas Plants in Minnesota



A 60-acre solar farm in Camp Ripley, a National Guard base in Minnesota.

A new report suggests the economics of large-scale batteries are reaching an important inflection point.

When it comes to renewable energy, Minnesota isn’t typically a headline-grabber: in 2016 it got about 18 percent of its energy from wind, good enough to rank in the top 10 states. 
But it’s just 28th in terms of installed solar capacity, and its relatively small size means projects within its borders rarely garner the attention that giants like California and Texas routinely get.

A new report on the future of energy in the state should turn some heads (PDF). According to the University of Minnesota’s Energy Transition Lab, starting in 2019 and for the foreseeable future, the overall cost of building grid-scale storage there will be less than that of building natural-gas plants to meet future energy demand.


Minnesota currently gets about 21 percent of its energy from renewables. That’s not bad, but current plans also call for bringing an additional 1,800 megawatts of gas-fired “peaker” plants online by 2028 to meet growing demand. As the moniker suggests, these plants are meant to spin up quickly to meet daily peaks in energy demand—something renewables tend to be bad at because the wind doesn’t always blow and the sun doesn’t always shine.

Storing energy from renewables could solve that problem, but it’s traditionally been thought of as too expensive compared with other forms of energy.

The new report suggests otherwise. According to the analysis, bringing lithium-ion batteries online for grid storage would be a good way to stockpile energy for when it’s needed, and it would prove less costly than building and operating new natural-gas plants.

The finding comes at an interesting time. For one thing, the price of lithium-ion batteries continues to plummet, something that certainly has the auto industry’s attention. And grid-scale batteries, while still relatively rare, are popping up more and more these days. The Minnesota report, then, suggests that such projects may become increasingly common—and could be a powerful way to lower emissions without sending our power bills skyrocketing in the process.
(Read more: Minnesota Public Radio, “Texas and California Have Too Much Renewable Energy,” 

“The One and Only Texas Wind Boom,” “By 2040, More Than Half of All New Cars Could Be Electric”)

New Battery Could Power Electric Cars 620 Miles (@ 1,000km) on Single Charge



The average American drives about 30 miles (48 kilometers) per day, according to AAA, yet many people are still reluctant to buy electric cars that can travel three times that distance on a single charge. 

This so-called range anxiety is one reason gasoline-powered vehicles still rule the road, but a team of scientists is working to ease those fears.

Mareike Wolter, Project Manager of Mobile Energy Storage Systems at Fraunhofer-Gesellschaft in Dresden, Germany, is working with a team on a new battery that would give electric cars a range of about 620 miles (1,000 km) on a single charge.



Wolter said the project began about three years ago when researchers from Fraunhofer as well as ThyssenKrupp System Engineering and IAV Automotive Engineering started brainstorming about how they could improve the energy density of automotive lithium batteries. 



They turned to the popular all-electric car, the Tesla, as a starting point. Tesla’s latest vehicle, the Model S 100D has a 100-kilowatt-hour battery pack, which reportedly gives it a range of 335 miles (540 km). 

The pack is large, about 16 feet long, 6 feet wide and 4 inches thick. It contains more than 8,000 lithium-ion battery cells, each one individually packaged inside a cylinder housing that measures about 2 to 3 inches (6 to 7 centimeters) high and about 0.8 inches (2 cm) across.

“We thought if we could use the same space as the battery in the Tesla, but improve the energy density and finally drive 1,000 km, this would be nice,” Wolter told Live Science.

One way of doing this would be to refine the materials inside the battery so that it could store more energy, she said. But another way would be to improve the system’s design as a whole, Wolter said. 

Nearly 50 percent of each cell is devoted to components such as the housing, the anode (the battery’s negative terminal), the cathode (the battery’s positive terminal) and the electrolyte, the liquid that transports the charged particles. 

Additional space is needed inside the car to wire the battery packs to the vehicle’s electrical system.

“It’s a lot of wasted space,” Wolter said. “You have a lot of inactive components in the system, and that’s a problem from our point of view.”

The scientists decided to reimagine the entire design, they said.


An illustration that shows how the new electric battery is stacked like a ream of paper. Credit: Fraunhofer IKTS

To do so, they got rid of the housings that encase individual batteries and turned to a thin, sheet-like design instead of a cylinder. 

Their metallic sheet is coated with an energy-storage material made from powdered ceramic mixed with a polymer binder. One side serves as the cathode, and other side serves as the anode.

The researchers stacked several of these so-called bipolar electrodes one on top of the other, like sheets of paper in a ream, separating the electrodes by thin layers of electrolyte and a material that prevents electrical charges from shorting out the whole system.

The “ream” is sealed within a package measuring about 10 square feet (1square meter), and contacts on the top and bottom connect to the car’s electrical system.

The goal is to build a battery system that fits in the same space as the one used by Tesla’s vehicles or other electric vehicles, the researchers said.

“We can put more electrodes storing the energy in the same space,” Wolter said.

She added that the researchers aim to have such a system ready to test in cars by 2020.

Original article on Live Science.

MIT: Tesla Not the Only Battery Game in Town ~ Electric Cars Could Be Cheaper Than Internal Combustion by 2030


German chancellor Angela Merkel visits Accumotive’s plant in Kamenz, Germany.

Tesla gets the headlines, but big battery factories are being built all over the world, driving down prices.

Battery production is booming, and Tesla is far from the only game in town.

According to Bloomberg New Energy Finance, global battery production is forecast to more than double between now and 2021. The expansion is in turn driving prices down, good news both for the budding electric-car industry and for energy companies looking to build out grid-scale storage to back up renewable forms of energy.


While Tesla gets tons of attention for its “gigafactories”—one in Nevada that will produce batteries, and another in New York that will produce solar panels
—the fact is, the company has a lot of battery-building competition.

Exhibit A is a new battery plant in Kamenz, Germany, run by Accumotive. The half-billion-euro facility broke ground on Monday with a visit from German chancellor Angela Merkel and will supply batteries to its parent company, Daimler, which is betting heavily on the burgeoning electric-vehicle market.

But the lion’s share of growth is expected to be in Asia. BYD, Samsung, LG, and Panasonic (which has partnered with Tesla) are all among the world’s top battery producers, and nine of the world’s largest new battery factories are under construction in China (paywall), according to Benchmark Minerals.

That competition means the steady downward trend in battery prices is going to continue. On a per-kilowatt-hour basis, costs have fallen from $542 in 2012 to around $139 today, according to analysis by Benchmark.

That makes for a huge difference in the cost of an electric car, of which 40 percent is usually down to the battery itself.


Bloomberg’s analysts have already said that the 2020s could be the decade in which electric cars take off—and one even went so far as to say that by 2030, electric cars could be cheaper than those powered by internal combustion.

Those watching the industry might worry that a flood of cheap batteries could end up hurting profitability for producers, as happened in the solar-panel business.

That could happen, but India and China, two huge rising automotive markets, are bullish about using electric cars to help solve problems like traffic congestion and air pollution. So even as supply ramps up, there is likely to be plenty of demand to go around.

MIT Technology Review: M. Reilly Sr. Editor

New battery coating could improve performance of smart phones and electric vehicles by 10X – But could still have Fire Safety Issues



High performing lithium-ion batteries are a key component of laptops, smart phones, and electric vehicles. Currently, the anodes, or negative charged side of lithium ion batteries, are generally made with graphite or other carbon-based materials.

But, the performance of carbon based materials is limited because of the weight and energy density, which is the amount of energy that can be stored in a given space. As a result, a lot of research is focused on lithium-metal anodes.

The success of lithium metal anodes will enable many battery technologies, including lithium metal and lithium air, which can potentially increase the capacity of today’s best lithium-ion batteries five to 10 times. That would mean five to 10 times more range for electric vehicles and smartphone batteries lasting five to 10 times more time. Lithium metal anodes are also lighter and less expensive.

The problem with lithium ion batteries made with metal is that during charge cycles they uncontrollably grow dendrites, which are microscopic fibers that look like tree sprouts. The dendrites degrade the performance of the battery and also present a safety issue because they can short circuit the battery and in some cases catch fire.

A team of researchers at the University of California, Riverside has made a significant advancement in solving the more than 40-year-old dendrite problem. Their findings were just published in the journal Chemistry of Materials (“In Situ Formation of Stable Interfacial Coating for High Performance Lithium Metal Anodes”).

Methyl Viologen Process


These are illustrations of the design principles of using methyl viologen to form a stable coating to allow the stable cycling of lithium metal. (Image: UC Riverside) (click on image to enlarge)

The team discovered that by coating the battery with an organic compound called methyl viologen they are able to stabilize battery performance, eliminate dendrite growth and increase the lifetime of the battery by more than three times compared to the current standard electrolyte used with lithium metal anodes.

“This has the potential to change the future,” said Chao Wang, an adjunct assistant professor of chemistry at UC Riverside who is the lead author of the paper. “It is low cost, easily manipulated and compatible with the current lithium ion battery industry.”

The researchers designed a new strategy to form a stable coating to enhance the lifetime of lithium-metal anodes. They used methyl viologen, which has been used in other applications because of its ability to change color when reduced.

The methyl viologen molecule used by the researchers can be dissolved in the electrolytes in the charged states. Once the molecules meet the lithium metal, they are immediately reduced to form a stable coating on top of the metal electrode.

By adding only .5 percent of viologen into the electrolyte, the cycling lifetime can already be enhanced by three times. In addition, methyl viologen is very low in cost and can easily be scaled up.

The stable operation of lithium metal anodes, which the researchers have achieved with the addition of methyl viologen, could enable the development of next generation high-capacity batteries, including lithium metal batteries and lithium air batteries.

Wang cautioned that while the coating improves battery performance, it isn’t a way to prevent batteries from catching fire.

Source: University of California – Riverside

Re-Writing The Rules Of Lithium Ion Batteries


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Ultrafast spectroscopy has revealed that components of the electrolyte play a much more important role in battery performance than previously thought.

Using ultrafast spectroscopic methods, researchers from the Center for Molecular Spectroscopy and Dynamics at the Institute for Basic Science (IBS) have challenged the existing theory on ion diffusion in the widely used lithium rechargeable batteries. Published in Nature Communications, this study reveals the interactions between lithium ions and electrolytes, organic molecules that surround the lithium ions and conduct electricity.

CNT Battery MjU2NDIyMQAlthough most of our electronic devices like mobile phones, laptops and electric vehicles use lithium rechargeable batteries, what is going on inside them is not actually fully understood. In a typical commercial lithium rechargeable battery, lithium ions dissolved in electrolytes move from the positive to the negative pole of the battery when the battery is charging, migrating in the opposite direction when the battery is in use. The lithium ion mobility determines the performance of the lithium rechargeable battery, and determines how rapidly they can charge and discharge. Lithium ions, however, do not migrate alone: they are surrounded by electrolytes that facilitate the journey from one pole to the other.

Currently, the electrolytes in our lithium rechargeable batteries are typically composed of a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) in equal concentration. It is believed that lithium ions associate mainly with EC, forming the so-called ‘solvation shell’ or ‘solvation sheath,’ while DMC and DEC just enhancing the movement of these shells between the batteries’ poles, like lubricants. However, while most of the previous studies focused on the static properties of the bond between electrolytes and lithium ions, this study clarifies the dynamics of the bonding. Like in a motion picture, where a series of still images displayed rapidly one after the other create the effect of movements, IBS scientists took successive shots to analyze the formation and breaking of these bonds.

However, while movies are typically filmed and displayed at 24 still images per seconds, these measurement ‘shots’ were taken at time intervals of just femtoseconds or 1/1,000,000,000,000,000 of a second. Thanks to a tool called two-dimensional infrared spectroscopy, the team measured how lithium ions bind to the oxygen atoms of DEC and found that these bonds break and form in a matter of 2-17 picoseconds.

The timescale is similar for DMC. This means that DMC and DEC are more than just lubricants, they are also part of the solvation shell together with EC and may play an active role in transporting lithium ions to the battery’s pole. “It was believed that EC makes a rigid shell around lithium ions during the migration between electrodes.

However, this study shows that the solvent shell is not that rigid, it is constantly restructured during the ion transport,” explained Professor Cho Minhaeng. “For this reason, revising the existing lithium ion diffusion theory is inevitable.” The research team is working on a follow-up study to establish a new theory of the lithium ion diffusion process and it is building a new ultra-high-speed laser spectroscopy instrument that can observe the chemical reaction as well as film it on top of the rechargeable batteries’ electrodes.

The article can be found at: Lee et al. (2017) Ultrafast Fluxional Exchange Dynamics in Electrolyte Solvation Sheath of Lithium Ion Battery. Read more from Asian Scientist Magazine at: https://www.asianscientist.com/2017/04/tech/lithium-battery-electrolyte-solvation-shell/

Nanotube-based Li-ion Batteries Can Charge to Near Maximum in Two Minutes but …


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Nanotube-based Li-ion Batteries Can Charge to Near Maximum in Two Minutes … but could our current grid system handle an ‘en masse’ switch to EV’s?

The prospects for ubiquitous all-electric vehicles (EVs) powered by lithium-ion (Li-ion) batteries took a bit of a hit back in 2010, when then U.S. Secretary of Energy Steven Chu addressed the United Nations Climate Change Conference in Cancun and suggested that, for battery powered cars to replace those powered by fossil fuels, some pretty significant improvements would need to be made to current technology.

Chu said at the time: “It will take a battery, first that can last for 15 years of deep discharges. You need about five as a minimum, but really six- or seven-times higher storage capacity and you need to bring the price down by about a factor of three.” Chu suggested it might take another five years before such a battery would be developed, and he was almost exactly right in his prediction.

Researchers at the Nanyang Technology University (NTU) in Singapore have achieved at least some of those criteria by developing a Li-ion battery capable of 20 years of deep discharges, more than 10 times that of existing Li-ion batteries.

In addition to longer battery life, the new battery design can be charged up quickly so that it can reach 70 percent of its maximum charge in just two minutes.

These features tick at least two of the metrics that Chu and others have indicated are key to making all-EVs compete with those running on fossil fuels. This would mean that EV owners would not have to spend roughly $5000 every two years for a completely new set of batteries. It could also allow for a quick stop of just a couple of minutes to significantly increase the driving range of the vehicle.

The key to the new Li-ion battery is the replacement of graphite at the anode with nanotubes synthesized from titanium dioxide. This is a departure from a lot of recent work toward improved anodes; other research teams have been using nanostructured silicon in place of graphite.

“With our nanotechnology, electric cars would be able to increase their range dramatically with just five minutes of charging, which is on par with the time needed to pump petrol for current cars,” said Chen Xiaodong, an associate professor at NTU Singapore, in a press release.

The new nanotube material, which is described in the journal Advanced Materials, is produced relatively easily, according to the researchers, by taking titanium dioxide nanoparticles and mixing them with sodium hydroxide. The real key to getting the long titanium dioxide nanotubes the nanoparticles yield is conducting the stirring process at the right temperature.

The technology has been patented and has been licensed by a company that says it could get a new generation of fast-charging batteries to market in two years.

While battery life and recharging have been significantly improved with the new battery design, it’s not clear that new batteries have a longer charge life, or what is known as gravimetric energy density (the amount of energy stored per unit mass). Instead, they have improved Li-ion’s relatively weak gravimetric power density (the maximum amount of power that can be supplied per unit mass) by eliminating the additives that are used to bind the electrodes to the anode. This allows the battery to transfer electrons and ions in and out of the battery more quickly. This translates into batteries that will last about the same amount of time on a charge as today’s current batteries, but can be charged up to near maximum very quickly.

NTU professor Rachid Yazami, who was the co-inventor of the lithium-graphite anode 34 years ago but not involved in this most recent research, has noted the significant improvement to Li-ion batteries this work represents.

Yazami said: “There is still room for improvement and one such key area is the power density—how much power can be stored in a certain amount of space—which directly relates to the fast charge ability. Ideally, the charge time for batteries in electric vehicles should be less than 15 minutes, which Prof Chen’s nanostructured anode has proven to do.”

Researchers @Imperial College of London uncover secret of nanomaterial that makes harvesting sunlight easier


Sun Harvest Nano Material 12-researchersuGold nanoparticles chemically guided inside the hot-spot of a larger gold bow-tie nanoantenna. Credit: Imperial College London

Using sunlight to drive chemical reactions, such as artificial photosynthesis, could soon become much more efficient thanks to nanomaterials.

 

This is the conclusion of a study published today led by researchers in the Department of Physics at Imperial College London, which could ultimately help improve solar energy technologies and be used for new applications, such as using sunlight to break down harmful chemicals.

Sunlight is used to drive many processes that would not otherwise occur. For example, carbon dioxide and water do not ordinarily react, but in the process of photosynthesis, plants take these two chemicals and, using sunlight, produce oxygen and sugar.

The efficiency of this is very high, meaning much of the energy from sunlight is transferred to the chemical reaction, but so far scientists have been unable to mimic this process in manmade artificial devices.

One reason is that many molecules that can undergo with light do not efficiently absorb the light themselves. They rely on photocatalysts – materials that absorb light efficiently and then pass the energy on to the molecules to drive reactions.

In the new study, researchers have investigated an artificial photocatalyst material using nanoparticles and found out how to make it more efficient.

This could lead to better solar panels, as the energy from the Sun could be more efficiently harvested. The photocatalyst could also be used to destroy liquid or gas pollutants, such as pesticides in water, by harnessing sunlight to drive reactions that break down the chemicals into less harmful forms.

Lead author Dr Emiliano Cortés from the Department of Physics at Imperial, said: “This finding opens new opportunities for increasing the efficiency of using and storing sunlight in various technologies.

“By using these materials we can revolutionize our current capabilities for storing and using with important implications in energy conversion, as well as new uses such as destroying pollutant molecules or gases and water cleaning, among others.”

The material that the team investigated is made of metal nanoparticles – particles only billionths of a metre in diameter. Their results are published today in the Journal Nature Communications.

The team, which included researchers from the Chemistry Department at University of Duisburg-Essen in Germany led by Professor Sebastian Schlücker and theoreticians from the Rensselaer Polytechnic Institute and Harvard University at the US, showed that light-induced chemical reactions occur in certain regions over the surface of these nanomaterials.

They identified which areas of the nanomaterial would be most suitable for transferring to chemical reactions, by tracking the locations of very small gold nanoparticles (used as a markers) on the surface of the silver nanocatalytic material.

Now that they know which regions are responsible for the process of harvesting light and transferring it to chemical reactions, the team hope to be able to engineer the nanomaterial to increase these areas and make it more efficient.

Lead researcher Professor Stefan Maier said: “This is a powerful demonstration of how metallic nanostructures, which we have investigated in my group at Imperial for the last 10 years, continue to surprise us in their abilities to control light on the nanoscale.

“The new finding uncovered by Dr Cortés and his collaborators in Germany and the US opens up new possibilities for this field in the areas photocatalysis and nanochemistry.”

Explore further: Artificial leaf as mini-factory for drugs

More information: Emiliano Cortés et al. Plasmonic hot electron transport drives nano-localized chemistry, Nature Communications (2017). DOI: 10.1038/NCOMMS14880

Stanford and Oxford scientists report New Perovskite low cost solar cell design could outperform existing commercial technologies: Video


stanford-oxfoed-perovskite_news-960x640Researchers have created a new type of solar cell that replaces silicon with a crystal called perovskite. This design converts sunlight to electricity at efficiencies similar to current technology but at much lower cost.

A new design for solar cells that uses inexpensive, commonly available materials could rival and even outperform conventional cells made of silicon.

Stanford and Oxford have created novel solar cells from crystalline perovskite that could outperform existing silicon cells on the market today. This design converts sunlight to electricity at efficiencies of 20 percent, similar to current technology but at much lower cost.

 

Writing in the Oct. 21 edition of Science, researchers from Stanford and Oxford describe using tin and other abundant elements to create novel forms of perovskite – a photovoltaic crystalline material that’s thinner, more flexible and easier to manufacture than silicon crystals.

Video: Stanford and Oxford scientists have created novel solar cells from crystalline perovskite that could rival and even outperform existing silicon cells on the market today. The new design converts sunlight to electricity at efficiencies of 20 percent, similar to current technology but at much lower cost.

In the video, Professor Michael McGehee and postdoctoral scholar Tomas Leijtens of Stanford describe the discovery, which could lead to thin-film solar cells with a record-setting 30% efficiency.

“Perovskite semiconductors have shown great promise for making high-efficiency solar cells at low cost,” said study co-author Michael McGehee, a professor of materials science and engineering at Stanford. “We have designed a robust, all-perovskite device that converts sunlight into electricity with an efficiency of 20.3 percent, a rate comparable to silicon solar cells on the market today.”

The new device consists of two perovskite solar cells stacked in tandem. Each cell is printed on glass, but the same technology could be used to print the cells on plastic, McGehee added.

“The all-perovskite tandem cells we have demonstrated clearly outline a roadmap for thin-film solar cells to deliver over 30 percent efficiency,” said co-author Henry Snaith, a professor of physics at Oxford. “This is just the beginning.”

Tandem technology

Previous studies showed that adding a layer of perovskite can improve the efficiency of silicon solar cells. But a tandem device consisting of two all-perovskite cells would be cheaper and less energy-intensive to build, the authors said.

Stanford post-doctoral scholar Tomas Leijtens and Professor Mike McGehee examine perovskite tandem solar cells.

Stanford post-doctoral scholar Tomas Leijtens and Professor Mike McGehee examine perovskite tandem solar cells. (Image credit: L.A. Cicero)

“A silicon solar panel begins by converting silica rock into silicon crystals through a process that involves temperatures above 3,000 degrees Fahrenheit (1,600 degrees Celsius),” said co-lead author Tomas Leijtens, a postdoctoral scholar at Stanford. “Perovskite cells can be processed in a laboratory from common materials like lead, tin and bromine, then printed on glass at room temperature.”

But building an all-perovskite tandem device has been a difficult challenge. The main problem is creating stable perovskite materials capable of capturing enough energy from the sun to produce a decent voltage.

A typical perovskite cell harvests photons from the visible part of the solar spectrum. Higher-energy photons can cause electrons in the perovskite crystal to jump across an “energy gap” and create an electric current.

A solar cell with a small energy gap can absorb most photons but produces a very low voltage. A cell with a larger energy gap generates a higher voltage, but lower-energy photons pass right through it.

An efficient tandem device would consist of two ideally matched cells, said co-lead author Giles Eperon, an Oxford postdoctoral scholar currently at the University of Washington.

“The cell with the larger energy gap would absorb higher-energy photons and generate an additional voltage,” Eperon said. “The cell with the smaller energy gap can harvest photons that aren’t collected by the first cell and still produce a voltage.”

Cross-section of new tandem solar cell

Cross-section of a new tandem solar cell designed by Stanford and Oxford scientists. The brown upper layer of perovskite captures low-energy lightwaves, and the red perovskite layer captures high-energy waves. (Image credit: Scanning electron microscopy image by Rebecca Belisle and Giles Eperon)

The smaller gap has proven to be the bigger challenge for scientists. Working together, Eperon and Leijtens used a unique combination of tin, lead, cesium, iodine and organic materials to create an efficient cell with a small energy gap.

“We developed a novel perovskite that absorbs lower-energy infrared light and delivers a 14.8 percent conversion efficiency,” Eperon said. “We then combined it with a perovskite cell composed of similar materials but with a larger energy gap.”

The result: A tandem device consisting of two perovskite cells with a combined efficiency of 20.3 percent.

“There are thousands of possible compounds for perovskites,” Leijtens added, “but this one works very well, quite a bit better than anything before it.”

Seeking stability

One concern with perovskites is stability. Rooftop solar panels made of silicon typically last 25 years or more. But some perovskites degrade quickly when exposed to moisture or light. In previous experiments, perovskites made with tin were found to be particularly unstable.

To assess stability, the research team subjected both experimental cells to temperatures of 212 degrees Fahrenheit (100 degrees Celsius) for four days.

“Crucially, we found that our cells exhibit excellent thermal and atmospheric stability, unprecedented for tin-based perovskites,” the authors wrote.

“The efficiency of our tandem device is already far in excess of the best tandem solar cells made with other low-cost semiconductors, such as organic small molecules and microcrystalline silicon,” McGehee said. “Those who see the potential realize that these results are amazing.”

The next step is to optimize the composition of the materials to absorb more light and generate an even higher current, Snaith said.

“The versatility of perovskites, the low cost of materials and manufacturing, now coupled with the potential to achieve very high efficiencies, will be transformative to the photovoltaic industry once manufacturability and acceptable stability are also proven,” he said.

Co-author Stacey Bent, a professor of chemical engineering at Stanford, provided key insights on tandem-fabrication techniques. Other Stanford coauthors are Kevin Bush, Rohit Prasanna, Richard May, Axel Palmstrom, Daniel J. Slotcavage and Rebecca Belisle. Oxford co-authors are Thomas Green, Jacob Tse-Wei Wang, David McMeekin, George Volonakis, Rebecca Milot, Jay Patel, Elizabeth S. Parrott, Rebecca Sutton, Laura Herz, Michael Johnston and Henry Snaith. Other co-authors are Bert Conings, Aslihan Babayigit and Hans-Gerd Boyen of Hasselt University in Belgium, and Wen Ma and Farhad Moghadam of SunPreme Inc.

Funding was provided by the Graphene Flagship, The Leverhulme Trust, U.K. Engineering and Physical Sciences Research Council, European Union Seventh Framework Programme, Horizon 2020, U.S. Office of Naval Research and the Global Climate and Energy Project at Stanford.

 

MIT.nano ~ Inspiring Innovation at the ‘nano-scale’ … Making Our World Better – One Atom at a Time: Video


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MIT-nanoMIT is constructing, at the heart of the campus, a new 200,000-square-foot center for nanoscience and nanotechnology. This advanced facility will be a place for tinkering with atoms, one by one—and for constructing, from these fantastically small building blocks, the innovations of the future. Watch the MIT Video then Read More …

 

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“Science is not only the disciple of Reason, but also one of Romance and Passion ~ Stephen B. Hawking

Nanotechnology is so small it’s measured in billionths of meters, and it is revolutionizing every aspect of our lives … Dictionary Series - Science: nanotechnology

The past 70 years have seen the way we live and work transformed by two tiny inventions. The electronic transistor and the microchip are what make all modern electronics possible, and since their development in the 1940s they have been getting smaller. Today, one chip can contain as many as 5 billion transistors. If cars had followed the same development pathway, we would now be able to drive them at 300,000 mph and they would cost just $6.00 (US) each.AmorChem Nanotechnology-300x200

But to keep this progress going we need to be able to create circuits on the extremely small, nanometer scale. A nanometer (nm) is one billionth of a meter and so this kind of engineering involves manipulating individual atoms. We can do this, for example, by firing a beam of electrons at a material, or by vaporizing it and depositing the resulting gaseous atoms layer by layer onto a base.

Read More: Nanotechnology is Changing EVERYTHING … Health Care, Clean Energy, Clean Water, Quantum Computing …

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