MIT: New type of electrolyte could enhance supercapacitor performance


  • Large anions with long tails (blue) in ionic liquids can make them self-assemble into sandwich-like bilayer structures on electrode surfaces. Ionic liquids with such structures have much improved energy storage capabilities.

  • Image: Xianwen Mao, MIT

  • Novel class of “ionic liquids” may store more energy than conventional electrolytes — with less risk of catching fire.

    Supercapacitors, electrical devices that store and release energy, need a layer of electrolyte — an electrically conductive material that can be solid, liquid, or somewhere in between. Now, researchers at MIT and several other institutions have developed a novel class of liquids that may open up new possibilities for improving the efficiency and stability of such devices while reducing their flammability.

    “This proof-of-concept work represents a new paradigm for electrochemical energy storage,” the researchers say in their paper describing the finding, which appears today in the journal Nature Materials.

    For decades, researchers have been aware of a class of materials known as ionic liquids — essentially, liquid salts — but this team has now added to these liquids a compound that is similar to a surfactant, like those used to disperse oil spills. With the addition of this material, the ionic liquids “have very new and strange properties,” including becoming highly viscous, says MIT postdoc Xianwen Mao PhD ’14, the lead author of the paper.

    “It’s hard to imagine that this viscous liquid could be used for energy storage,” Mao says, “but what we find is that once we raise the temperature, it can store more energy, and more than many other electrolytes.”

    That’s not entirely surprising, he says, since with other ionic liquids, as temperature increases, “the viscosity decreases and the energy-storage capacity increases.”

    But in this case, although the viscosity stays higher than that of other known electrolytes, the capacity increases very quickly with increasing temperature. That ends up giving the material an overall energy density — a measure of its ability to store electricity in a given volume — that exceeds those of many conventional electrolytes, and with greater stability and safety.

    The key to its effectiveness is the way the molecules within the liquid automatically line themselves up, ending up in a layered configuration on the metal electrode surface. The molecules, which have a kind of tail on one end, line up with the heads facing outward toward the electrode or away from it, and the tails all cluster in the middle, forming a kind of sandwich. This is described as a self-assembled nanostructure.

    “The reason why it’s behaving so differently” from conventional electrolytes is because of the way the molecules intrinsically assemble themselves into an ordered, layered structure where they come in contact with another material, such as the electrode inside a supercapacitor, says T. Alan Hatton, a professor of chemical engineering at MIT and the paper’s senior author. “It forms a very interesting, sandwich-like, double-layer structure.”

    This highly ordered structure helps to prevent a phenomenon called “overscreening” that can occur with other ionic liquids, in which the first layer of ions (electrically charged atoms or molecules) that collect on an electrode surface contains more ions than there are corresponding charges on the surface.

    This can cause a more scattered distribution of ions, or a thicker ion multilayer, and thus a loss of efficiency in energy storage; “whereas with our case, because of the way everything is structured, charges are concentrated within the surface layer,” Hatton says.

    The new class of materials, which the researchers call SAILs, for surface-active ionic liquids, could have a variety of applications for high-temperature energy storage, for example for use in hot environments such as in oil drilling or in chemical plants, according to Mao. “Our electrolyte is very safe at high temperatures, and even performs better,” he says. In contrast, some electrolytes used in lithium-ion batteries are quite flammable.

    The material could help to improve performance of supercapacitors, Mao says. Such devices can be used to store electrical charge and are sometimes used to supplement battery systems in electric vehicles to provide an extra boost of power.

    Using the new material instead of a conventional electrolyte in a supercapacitor could increase its energy density by a factor of four or five, Mao says. Using the new electrolyte, future supercapacitors may even be able to store more energy than batteries, he says, potentially even replacing batteries in applications such as electric vehicles, personal electronics, or grid-level energy storage facilities.

    The material could also be useful for a variety of emerging separation processes, Mao says. “A lot of newly developed separation processes require electrical control,” in various chemical processing and refining applications and in carbon dioxide capture, for example, as well as resource recovery from waste streams. These ionic liquids, being highly conductive, could be well-suited to many such applications, he says.

    The material they initially developed is just an example of a variety of possible SAIL compounds. “The possibilities are almost unlimited,” Mao says. The team will continue to work on different variations and on optimizing its parameters for particular uses. “It might take a few months or years,” he says, “but working on a new class of materials is very exciting to do. There are many possibilities for further optimization.”

    The research team included Paul Brown, Yinying Ren, Agilio Padua, and Margarida Costa Gomes at MIT; Ctirad Cervinka at École Normale Supérieure de Lyon, in France; Gavin Hazell and Julian Eastoe at the University of Bristol, in the U.K.; Hua Li and Rob Atkin at the University of Western Australia; and Isabelle Grillo at the Institut Max-von-Laue-Paul-Langevin in Grenoble, France. The researchers dedicate their paper to the memory of Grillo, who recently passed away.

    “It is a very exciting result that surface-active ionic liquids (SAILs) with amphiphilic structures can self-assemble on electrode surfaces and enhance charge storage performance at electrified surfaces,” says Yi Cui, a professor of materials science and engineering at Stanford University, who was not associated with this research. “The authors have studied and understood the mechanism. The work here might have a great impact on the design of high energy density supercapacitors, and could also help improve battery performance,” he says.

    Nicholas Abbott, the Tisch University Professor at Cornell University, who also was not involved in this work, says “The paper describes a very clever advance in interfacial charge storage, elegantly demonstrating how knowledge of molecular self-assembly at interfaces can be leveraged to address a contemporary technological challenge.”

    The work was supported by the MIT Energy Initiative, an MIT Skoltech fellowship, and the Czech Science Foundation.

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    New discovery makes fast-charging, better performing lithium-ion batteries possible


    New Electrode 23c4a3_036cc463e8e9458d9a2070b7b7bb8c5c_mv2

    April –  2019 – Rensselaer Polytechnic Institute – Material Science

    Creating a lithium-ion battery that can charge in a matter of minutes but still operate at a high capacity is possible, according to research from Rensselaer Polytechnic Institute just published in Nature Communications. This development has the potential to improve battery performance for consumer electronics, solar grid storage, and electric vehicles.

    A lithium-ion battery charges and discharges as lithium ions move between two electrodes, called an anode and a cathode. In a traditional lithium-ion battery, the anode is made of graphite, while the cathode is composed of lithium cobalt oxide.

    These materials perform well together, which is why lithium-ion batteries have become increasingly popular, but researchers at Rensselaer believe the function can be enhanced further.

    “The way to make batteries better is to improve the materials used for the electrodes,” said Nikhil Koratkar, professor of mechanical, aerospace, and nuclear engineering at Rensselaer, and corresponding author of the paper. “What we are trying to do is make lithium-ion technology even better in performance.”

    Vanadium Sulfide download

    Vanadium disulfide – a promising new monolayer material for Li-ion batteries

    Koratkar’s extensive research into nanotechnology and energy storage has placed him among the most highly cited researchers in the world. In this most recent work, Koratkar and his team improved performance by substituting cobalt oxide with vanadium disulfide (VS2).

    “It gives you higher energy density, because it’s light. And it gives you faster charging capability, because it’s highly conductive. From those points of view, we were attracted to this material,” said Koratkar, who is also a professor in the Department of Materials Science and Engineering.

    Excitement surrounding the potential of VS2 has been growing in recent years, but until now, Koratkar said, researchers had been challenged by its instability–a characteristic that would lead to short battery life. The Rensselaer researchers not only established why that instability was happening, but also developed a way to combat it.

    The team, which also included Vincent Meunier, head of the Department of Physics, Applied Physics, and Astronomy, and others, determined that lithium insertion caused an asymmetry in the spacing between vanadium atoms, known as Peierls distortion, which was responsible for the breakup of the VS2 flakes. They discovered that covering the flakes with a nanolayered coating of titanium disulfide (TiS2)–a material that does not Peierls distort–would stabilize the VS2 flakes and improve their performance within the battery.

    “This was new. People hadn’t realized this was the underlying cause,” Koratkar said. “The TiS2 coating acts as a buffer layer. It holds the VS2 material together, providing mechanical support.”

    Once that problem was solved, the team found that the VS2-TiS2 electrodes could operate at a high specific capacity, or store a lot of charge per unit mass. Koratkar said that vanadium and sulfur’s small size and weight allow them to deliver a high capacity and energy density. Their small size would also contribute to a compact battery.

    When charging was done more quickly, Koratkar said, the capacity didn’t dip as significantly as it often does with other electrodes. The electrodes were able to maintain a reasonable capacity because, unlike cobalt oxide, the VS2-TiS2 material is electrically conductive.

    Koratkar sees multiple applications for this discovery in improving car batteries, power for portable electronics, and solar energy storage where high capacity is important, but increased charging speed would also be attractive.

    Rensselaer college-photo_3861

    Rensselaer Polytechnic Institute

     

    Vanadium disulfide flakes with nanolayered titanium disulfide coating as cathode materials in lithium-ion batteries Lu Li, Zhaodong Li, Anthony Yoshimura, Congli Sun, Tianmeng Wang, Yanwen Chen, Zhizhong Chen, Aaron Littlejohn, Yu Xiang, Prateek Hundekar, Stephen F. Bartolucci, Jian Shi, Su-Fei Shi, Vincent Meunier, Gwo-Ching Wang & Nikhil Koratkar Nature Communications volume 10, Article number: 1764 (2019)

    Rensselaer Polytechnic Institute

    #Batteries #Energy #MaterialScience

    Graphene-based ink may lead to printable energy storage devices


    Top) The salt-templated process of synthesizing graphene nanosheets into ink. (Bottom) The ink and printed demonstration. Credit: Wei et al. ©2019 American Chemical Society

    Researchers have created an ink made of graphene nanosheets, and demonstrated that the ink can be used to print 3-D structures. As the graphene-based ink can be mass-produced in an inexpensive and environmentally friendly manner, the new methods pave the way toward developing a wide variety of printable energy storage devices.

    The researchers, led by Jingyu Sun and Zhongfan Liu at Soochow University and the Beijing Graphene Institute, and Ya-yun Li at Shenzhen University, have published a paper on their work in a recent issue of ACS Nano.

    “Our work realizes the scalable and green synthesis of nitrogen-doped  nanosheets on a salt template by direct chemical vapor deposition,” Sun told Phys.org. “This allows us to further explore thus-derived inks in the field of printable energy storage.”

    As the scientists explain, a key goal in graphene research is the mass production of graphene with high quality and at low cost. Energy-storage applications typically require graphene in powder form, but so far production methods have resulted in powders with a large number of structural defects and chemical impurities, as well as nonuniform layer thickness. This has made it difficult to prepare high-quality graphene inks.

    In the new paper, the researchers have demonstrated a new method for preparing graphene inks that overcomes these challenges. The method involves growing nitrogen-doped graphene nanosheets over NaCl crystals using direct chemical vapor deposition, which causes molecular fragments of nitrogen and carbon to diffuse on the surface of the NaCl crystals. The researchers chose NaCl due to its natural abundance and low cost, as well as its water solubility.

    To remove the NaCl, the coated crystals are submerged in water, which causes the NaCl to dissolve and leave behind pure nitrogen-doped graphene cages. In the final step, treating the cages with ultrasound transforms the cages into 2-D nanosheets, each about 5-7 graphite layers thick.

    The resulting nitrogen-doped graphene nanosheets have relatively few defects and an ideal size (about 5 micrometers in side length) for printing, as larger flakes can block the nozzle.

    To demonstrate the nanosheets’ effectiveness, the researchers printed a wide variety of 3-D structures using inks based on the graphene sheets.

    Among their demonstrations, the researchers used the ink as a conductive additive for an  (vanadium nitride) and used the composite ink to print flexible electrodes for supercapacitors with high power density and good cyclic stability. 

    In a second demonstration, the researchers created a composite ink made of the graphene sheets along with binder material (polypropylene) for printing interlayers for Li−S batteries.

    Compared to batteries with separators made only of the conventional material, those made with the composite material exhibited enhanced conductivity, leading to an overall improvement in battery performance.

    “In the future, we plan to exploit the direct technique for the mass production of high-quality graphene powders toward emerging printable energy storage applications,” Sun said.

    More information: Nan Wei et al. “Scalable Salt-Templated Synthesis of Nitrogen-Doped Graphene Nanosheets toward Printable Energy Storage.” ACS Nano. DOI: 10.1021/acsnano.9b03157

    Journal information: ACS Nano

    The Tesla Effect is Reaching Critical Mass – Could it Really Put Big Oil on the Defensive … Really?


    Tesla-S3X-Semi-fleet-press-photo-e1548882286108-1024x523

    *** This article appeared in TESLARATI and was re-posted in Fully Charged. We have Followed and Written a LOT about the ‘Coming EV Revolution’, about Advances in Charging Stations and Battery Technology. Most recently we posted an article ‘What If Green Energy Isn’t the Future?’

    So maybe … just maybe, ‘Green Energy’ might NOT be able to meet the current Projected Carbon Fuel Replacement Schedule …. However, could the EV/ Hydrogen Fuel Cell Revolution replace forever the Internal Combustion Engine (ICE)?  (Hint: We Think So!)

    Let Us Know What YOU think! Leave us your thoughts and comments. (below)

    Headed by vehicles like the Tesla Model 3, the electric car revolution is showing no signs of stopping. The auto landscape today is very different from what it was years ago. Before, only Tesla and a few automakers were pushing electric cars, and the Model S was proving to the industry that EVs could be objectively better than internal combustion vehicles. Today, practically every automaker has plans to release electric cars. EV startup Bollinger Motors CEO Robert Bollinger summed it up best: “If you want to start a (car company) now, it has to be electric.”

    CATALYSTS FOR A TRANSITION

    A critical difference between then and now is that veteran automakers today are coming up with decent electric vehicles. No longer were EVs glorified golf carts and compliance cars; today’s electric vehicles are just as attractive, sleek, and powerful than their internal combustion peers. The auto industry has warmed up to electric vehicles as well. The Jaguar I-PACE has been collecting awards left and right since its release, and more recently, the Kia Niro EV was dubbed by Popular Mechanics as the recipient of its Car of the Year award.

    A survey by CarGurus earlier this year revealed that 34% of car buyers are open to purchasing an electric car within the next ten years. A survey among young people in the UK last year revealed even more encouraging results, with 50% of respondents stating that they want electric cars. Amidst the disruption being brought about by the Tesla Model 3, which has all but dominated EV sales since production ramped last year, experienced automakers have responded in kind. Volkswagen recently debuted the ID.3, Audi has the e-tron, Hyundai has the Kona EV, and Mercedes-Benz has the EQC. Even Porsche, a low-volume car manufacturer, is attracting the high-end legacy market with the Taycan.

    At this point, it appears that Tesla’s mission is going well underway. With the market now open to the idea of electric vehicles, there is an excellent chance that EV adoption will only increase from this point on.

    Tesla CEO Elon Musk unveils the Tesla Semi. (Credit: Tesla)

    BIG OIL FEELS A CHANGE IN THE WIND

    Passenger cars are the No.1 source of demand for oil, and with the potential emergence of a transportation industry whose life and death does not rely on a gas pump, Big Oil could soon find itself on the defensive. Depending on how quickly the auto industry could shift entirely to sustainable transportation and how seriously governments handle issues like climate change, “peak oil” could happen a couple of decades or a few years from now. This could adversely affect investors in the oil industry, who might be at risk of losing their investments if peak oil happens faster than expected. JJ Kinahan, chief market strategist at TD Ameritrade, described this potential scenario in a statement to CNN. “Look at what happened to the coal industry. You have to keep that in the back of your mind and be vigilant. It can turn very, very quickly,” the strategist said.

    Paul Sankey of Mizuho Securities previously mentioned that a “Tesla Effect” is starting to be felt in the oil markets. According to the analyst, the Tesla Effect is an increasingly prevalent concept today which states that while the 20th century was driven by oil, the 21st century will be driven by electricity. This, together with the growing movements against climate change today, does not bode well for the oil industry. Adam White, an equity strategist at SunTrust Advisory, stated that investors might not be looking at the oil market with optimism anymore. “A lot of damage has already been done. People are jaded towards the industry,” he said.

    Prospective oil developments have been fraudulently overvalued, as claimed by a Complaint filed against Exxon. (Photo: Pixabay)

    An analysis from Barclays points to the world’s reliance on oil peaking somewhere between 2030 and 2035, provided that countries keep to their low-carbon goals. The investment bank also noted that peak oil could happen as early as 2025 if more aggressive climate change initiatives are adopted on a wider scale. This all but makes investments in oil stocks very risky in the 2020s, and this risk gets amplified if electric vehicles become more mainstream. Sverre Alvik of research firm DNV GL described this concern. “By 2030, oil shareholders will feel the impact. Electric vehicles are likely to cause light vehicle oil demand to plunge by nearly 50% by 2040,” Alvik said.

    Some of today’s prolific oil producers appear to be making the necessary preparations for peak oil’s inevitable decline. Amidst pressures from shareholders, BP, Royal Dutch Shell, and Total have expanded their operations into solar, wind, and electric charging, seemingly as a means to future-proof themselves. On the flipside, there are also big oil players that are ramping their activities. Earlier this month, financial titan Warren Buffet, who recently expressed his skepticism towards Elon Musk’s plan of introducing an insurance service for Tesla’s electric cars, committed $10 billion to Occidental Petroleum, one of the largest oil and gas exploration companies in the United States.

    A POINT OF NO RETURN

    The auto industry is now at a point where a real transition towards electrification is happening. Tesla’s efforts over the years, from the original Roadster to the Model 3, have played a huge part in this transition. Tesla, as well as its CEO, Elon Musk, have awakened the public’s eye about the viability of electric cars, while showing the auto industry that there is a demand for good, well-designed EVs. Nevertheless, Tesla still has a long journey ahead of it, as the company ramps its activities in the energy storage sector. If Tesla Energy mobilizes and becomes as disruptive as the company’s electric car division, it would deal yet another blow to the oil industry.

    At this point, it is pertinent for veteran automakers that have released their own electric cars to ensure that they do not stop. Legacy car makers had long talked the talk when it came to electric vehicles, but today, it is time to walk the walk. German automaker Volkswagen could be a big player in this transition, as hinted at by the reception of its all-electric car, the ID.3. The ID.3 launch was successful, with Volkswagen getting 10,000 preorders for the vehicle in just 24 hours. The German carmaker should see this as writing on the wall: the demand for EVs is there.

    The Volkswagen ID.3. (Credit: Volkswagen)

    The Volkswagen ID.3 is not as quick or sleek as a Tesla Model 3, nor does it last as long on the road between charges. But considering its price point and its badge, it does not have to be. Volkswagen states that the ID.3 will be priced below 40,000 euros ($45,000) in Germany, which should make it attainable for car buyers in the country.  If done right, the ID.3 could be the second coming of the Beetle, ultimately becoming a car that redeems the company from the stigma of the Dieselgate scandal. Thus, it would be a great shame if Volkswagen drops the ball on the ID.3.

    Tesla will likely remain a divisive company for years to come; Elon Musk, even more so. Nevertheless, Tesla and what it stands for is slowly becoming an idea, one that connotes hope for something better and cleaner for the future. And if history’s victories and tragedies are any indication, once something becomes an idea, an intangible concept, it becomes impossible to kill.

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    Mobility Disruption | Tony Seba

    Tony Seba, Silicon Valley entrepreneur, Author and Thought Leader, Lecturer at Stanford University, Keynote The reinvention and connection between infrastructure and mobility will fundamentally disrupt the clean transport model.

    Nano-Enabled Batteries and Super Capacitors

    What if Green Energy Isn’t the Future?


    Green W not future ED-AY628_Mills_GR_20190515162804A gas-filtration system atop a well, managed by Anadarko in Pennsylvania, Sept. 8, 2012.Photo: Robert Nicklesberg /Getty Images

    What’s Warren Buffett doing with a $10 billion bet on the future of oil and gas, helping old-school Occidental Petroleum buy Anadarko, a U.S. shale leader? For pundits promoting the all-green future, this looks like betting on horse farms circa 1919.

    Meanwhile, broad market sentiment is decidedly bearish on hydrocarbons. The oil and gas share of the S&P 500 is at a 40-year low, and the first quarter of 2019 saw the Nasdaq Clean Edge Green Energy Index and “clean tech” exchange-traded funds outperform the S&P.

    A week doesn’t pass without a mayor, governor or policy maker joining the headlong rush to pledge or demand a green energy future.

    Some 100 U.S. cities have made such promises. Hydrocarbons may be the source of 80% of America’s and the world’s energy, but to say they are currently out of favor is a dramatic understatement.

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    Yet it’s both reasonable and, for contrarian investors, potentially lucrative to ask: What happens if renewables fail to deliver?

    The prevailing wisdom has wind and solar, paired with batteries, adding 250% more energy to the world over the next two decades than American shale has added over the past 15 years.

    Is that realistic? The shale revolution has been the single biggest addition to the world energy supply in the past century. And even bullish green scenarios still see global demand for oil and gas rising, if more slowly.

    Q: If the favored alternatives fall short of delivering what growing economies need, will markets tolerate energy starvation? Not likely. Nations everywhere will necessarily turn to hydrocarbons.

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    And just how big could the call on oil and natural gas—and coal, for that matter—become if, say, only half as much green-tech energy gets produced as is now forecast? Keep in mind that a 50% “haircut” would still mean unprecedented growth in green-tech.

    If the three hydrocarbons were each to supply one-third of such a posited green shortfall, global petroleum output would have to increase by an amount equal to doubling the production of the Permian shale field (Anadarko’s home). And the world supply of liquid natural gas would need to increase by an amount equal to twice Qatar’s current exports, plus coal would have to almost double what the top global exporter, Australia, now ships.

    Green forecasters are likely out over their skis. All the predictions assume that emerging economies—the least wealthy nations—will account for more nearly three-fourths of total new spending on renewables. That won’t happen unless the promised radical cost reductions occur.

    For a bellwether reality-check, note that none of the wealthy nations that are parties to the Paris Accord—or any of the poor ones, for that matter—have come close to meeting the green pledges called for. In fact, let’s quote the International Energy Agency on what has actually happened: “Energy demand worldwide [in 2018] grew by . . . its fastest pace this decade . . . driven by a robust global economy . . . with fossil fuels meeting nearly 70% of the growth for the second year running.”

    The reason? Using wind, solar and batteries as the primary sources of a nation’s energy supply remains far too expensive. You don’t need science or economics to know that. Simply propose taking away subsidies or mandates, and you’ll unleash the full fury of the green lobby.

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    Meanwhile, there are already signs that the green vision is losing luster. Sweden’s big shift to wind power has not only created alarm over inadequate electricity supplies; it’s depressing economic growth and may imperil that nation’s bid for the 2026 Winter Olympics. China, although adept at green virtue-signaling, has quietly restarted massive domestic coal-power construction and is building hundreds of coal plants for emerging economies around the world.

    In the U.S., utilities, furiously but without fanfare, have been adding billions of dollars of massive oil- and natural-gas-burning diesel engines to the grid. Over the past two decades, three times as much grid-class reciprocating engine capacity has been added to the U.S. grid as in the entire half-century before. It’s the only practical way to produce grid-scale electricity fast enough when the wind dies off. Sweden will doubtless be forced to do the same.

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    A common response to all of the above: Make more electric cars. But mere arithmetic reveals that even the optimists’ 100-fold growth in electric vehicles wouldn’t displace more than 5% of global oil demand in two decades. Tepid growth in gasoline demand would be more than offset by growing economies’ appetites for air travel and manufactured goods. Goodness knows what would happen if Trump-like economic growth were to take hold in the rest of the developed world. As Mr. Buffett knows, the IEA foresees the U.S. supplying nearly three-fourths of the world’s net new demand for oil and gas.

    Green advocates can hope to persuade governments—and thus taxpayers—to deploy a huge tax on hydrocarbons to ensure more green construction. But there’s no chance that wealthy nations will agree to subsidize expensive green tech for the rest of the world.

    And we know where the Oracle of Omaha has placed a bet.

    Re-Posted from the Wall Street Journal – Mr. Mills is a senior fellow at the Manhattan Institute and a partner in Cottonwood Venture Partners, an energy-tech venture fund, and author of the recent report, “The ‘New Energy Economy’: An Exercise in Magical Thinking.”

     

    Rice University – Flexible insulator offers high strength and superior thermal conduction – Applications for Flexible Electronics and Energy Storage


     

    flexible insulator offers high strength and superior thermal conduction
    Rice University research scientist M.M. Rahman holds a flexible dielectric made of a polymer nanofiber layer and boron nitride. The new material stands up to high temperatures and could be ideal for flexible electronics, energy storage and electric devices where heat is a factor. Credit: Jeff Fitlow/Rice University

    A nanocomposite invented at Rice University’s Brown School of Engineering promises to be a superior high-temperature dielectric material for flexible electronics, energy storage and electric devices.

    The nanocomposite combines one-dimensional  nanofibers and two-dimensional  nanosheets. The nanofibers reinforce the self-assembling material while the “white graphene” nanosheets provide a thermally conductive network that allows it to withstand the heat that breaks down common dielectrics, the polarized insulators in batteries and other devices that separate positive and negative electrodes.

    The discovery by the lab of Rice  scientist Pulickel Ajayan is detailed in Advanced Functional Materials.

    Research scientist M.M. Rahman and postdoctoral researcher Anand Puthirath of the Ajayan lab led the study to meet the challenge posed by next-generation electronics: Dielectrics must be thin, tough, flexible and able to withstand .

    “Ceramic is a very good dielectric, but it is mechanically brittle,” Rahman said of the common material. “On the other hand, polymer is a good dielectric with good mechanical properties, but its thermal tolerance is very low.”

    Boron  is an electrical insulator, but happily disperses heat, he said. “When we combined the polymer nanofiber with boron nitride, we got a material that’s mechanically exceptional, and thermally and chemically very stable,” Rahman said.

    A lab video shows how quickly heat disperses from a composite of a polymer nanoscale fiber layer and boron nitride nanosheets. When exposed to light, both materials heat up, but the plain polymer nanofiber layer on the left retains the heat far longer than the composite at right. Credit: Ajayan Research Group/Rice University

    The 12-to-15-micron-thick material acts as an effective heat sink up to 250 degrees Celsius (482 degrees Fahrenheit), according to the researchers. Tests showed the polymer nanofibers-boron nitride combination dispersed heat four times better than the polymer alone.

    In its simplest form, a single layer of polyaramid nanofibers binds via van der Waals forces to a sprinkling of boron nitride flakes, 10% by weight of the final product. The flakes are just dense enough to form a heat-dissipating network that still allows the composite to retain its flexibility, and even foldability, while maintaining its robustness. Layering polyaramid and boron nitride can make the material thicker while still retaining flexibility, according to the researchers.

    “The 1D polyaramid  has many interesting properties except thermal conductivity,” Rahman said. “And  nitride is a very interesting 2-D material right now. They both have different independent properties, but when they are together, they make something very unique.”

    Rahman said the material is scalable and should be easy to incorporate into manufacturing.


    Explore further

    New material to pave the way for more efficient electronic devices


    More information: Muhammad M. Rahman et al. Fiber Reinforced Layered Dielectric Nanocomposite, Advanced Functional Materials (2019). DOI: 10.1002/adfm.201900056

    Journal information: Advanced Functional Materials
    Provided by Rice University

    Report: Levelized Cost of Energy for Lithium-Ion Batteries Is Plummeting


    Bloomberg New Energy Finance finds the long-term costs of multi-hour energy storage can compete with natural gas and coal in an increasing number of markets today.

    The long-term cost of supplying grid electricity from today’s lithium-ion batteries is falling even faster than expected, making them an increasingly cost-competitive alternative to natural-gas-fired power plants across a number of key energy markets. 

    That’s the key finding from a Tuesday report from Bloomberg New Energy Finance on the levelized cost of energy (LCOE) — the cost of a technology delivering energy over its lifespan — for a number of key clean energy technologies worldwide.

    Read More: Four Charts that Show the Future of Battery Storage

    According to its analysis of public and proprietary data from more than 7,000 projects worldwide, this benchmark LCOE for lithium-ion batteries has fallen by 35 percent, to $187 per megawatt-hour, since the first half of 2018. This precipitous decline has outpaced the continuing slide in LCOE for solar PV and onshore and offshore wind power. 

    Over the past year, offshore wind saw a 24 percent decline in LCOE to fall below $100 per megawatt-hour, compared to about $220 per megawatt-hour only five years ago.

    The benchmark LCOE for onshore wind and solar PV fell by 10 percent and 18 percent, respectively, to reach $50 and $57 per megawatt-hour for projects starting construction in early 2019. 

    To be sure, these generation technologies are still far cheaper than batteries in terms of their LCOEs — and that’s not mentioning the fact that they actually make electricity, rather than simply storing it for later use. To convert a battery’s storage capacity into a LCOE figure, the report models a utility-scale battery installation running daily cycles, with charging costs assumed to be at 60 percent of the wholesale base power price for the country in question.  

    Even so, the pace of the decline in battery LCOE, particularly for multi-hour storage applications that previous generations of lithium-ion technologies have struggled to provide, is startling, BNEF notes. Since 2012, the benchmark LCOE of lithium-ion batteries configured to supply four hours of grid power — a standard requirement for many grid services — has fallen by 74 percent, as extrapolated from historical data.

    In comparison, the LCOE per megawatt-hour for onshore wind, solar PV and offshore wind has fallen by 49 percent, 84 percent and 56 percent, respectively, since 2010.

    In fact, the LCOE for multi-hour lithium-ion batteries is falling to the point that “batteries co-located with solar or wind projects are starting to compete, in many markets and without subsidy, with coal- and gas-fired generation for the provision of ‘dispatchable power’ that can be delivered whenever the grid needs it (as opposed to only when the wind is blowing, or the sun is shining),” the report notes. 

    These findings match those we’ve been covering from our own analysts at Wood Mackenzie Power & Renewables, as well as from the broader industry. In the past year and a half, several large-scale solar-battery requests for proposals have set record-low prices, including Xcel Energy in Colorado with solar-plus-storage bids as low as $36 per megawatt-hour, compared to $25 per megawatt-hour for standalone solar, and NV Energy reporting even lower bids in its solar and solar-plus-storage RFPs.

    These price points equate to about a $6 to $7 per megawatt-hour premium for solar projects that are partially “dispatchable” in the manner of a traditional power plant, compared to standalone solar, Ravi Manghani, WoodMac energy storage research director, reported at Greentech Media’s Energy Storage Summit in December. 

    Just this week, clean energy advocacy and research organization Energy Innovation and Vibrant Clean Energy released a report finding that the LCOE of new renewables in the U.S. is lower than that of nearly three-quarters of the U.S. coal fleet — a not completely surprising finding, given the coal power industry’s well-documented challenges in competing with cheap natural gas, and increasingly cheap wind and solar power. 

    At the same time, it’s worth noting that the current trends in pricing for lithium-ion batteries, what they actually cost today, has been mixed. While continuing technology improvements and increasing scale of manufacturing have continued to push down prices, these have been somewhat counterbalanced in the past year or so by a bottleneck in available supply, driven by a boom in demand from big projects in the U.S. and South Korea. 

    WoodMac discovered that battery rack prices fell by only about 6 percent from 2017 to 2018, rather than the 14 percent range previously predicted, based on these supply shortage challenges.

    Article from GreenTech Media

    Everybody Wants EV Charging Stations ~ Almost Nobody Wants to Build Them – Why?


     

    MT Highway 1 images

             A Lonely Stretch of Highway in Wyoming

    A driver planning to make the trek from Denver to Salt Lake City can look forward to an eight-hour trip across some of the most beautiful parts of the country, long stretches with nary a town in sight. The fastest route would take her along I-80 through southern Wyoming. For 300 miles between Laramie and Evanston, she would see, according to a rough estimate, no fewer than 40 gas stations where she could fuel up her car. But if she were driving an electric vehicle, she would see just four charging stations where she could recharge her battery.

    The same holds true across the country. Gas stations outnumber public charging stations by around seven to one. It’s no wonder people get so nervous about driving an electric car.

    EV charge 1 images

    Numerous studies have shown that consumers steer clear of EVs because they worry about the lack of charging stations. Studies also show that consumers are more likely to buy an electric car when they see stations around town. While fears about range anxiety are largely unfounded — even the cheapest EVs sport enough range to serve nearly all of a driver’s needs — the paucity of charging stations is a real concern on longer trips, and it is deterring consumers from going all-electric.

    To be clear, it’s not just consumers who want to see more chargers. Charging stations are a boon to automakers, who want to sell electric cars, as well as to power utilities, who want to sell more electricity. Some utilities and automakers are investing huge sums into setting up charging stations — including Volkswagen’s commitment to spend $2 billion on EV charging infrastructure as part of their settlement over the diesel emissions scandal. But by and large, automakers and power companies are not putting a lot of money towards charging infrastructure.

    “I think the biggest problem with charging stations is there is no one responsible for installing charging stations,” said Nick Sifuentes, executive director at Tri-State Transportation Campaign. “So you see some automakers, like Tesla, installing charging stations. You see charging stations occasionally getting put out as part of a municipal planning process,” he said, “but for the most part, there is no one entity or group that feels responsible for that duty.”

    Power utilities have a big interest in EVs. Despite continued economic growth, demand for electricity has stayed flat over the last decade, as businesses slash energy use and consumers switch to more power-thrifty appliances — LED light bulbs, flat-screen TVs, high-efficiency washers and dryers. EVs could drive up the demand for electricity, throwing a lifeline to power utilities. And yet, these companies largely aren’t building charging stations.

    “For power utilities, the question is whether they see it as something that’s actually in their bailiwick or not,” Sifuentes said. Policymakers have not directed utilities to build out EV infrastructure, and with so few electric cars on the road, utilities are unlikely to take it upon themselves to start building charging stations.

             The Tesla Model 3

    “The problem is that the charging infrastructure doesn’t have a viable business model yet,” said David Greene, a professor of civil and environmental engineering at the University of Tennessee. “Although, there are some companies who are working on it really hard.”

    Private firms like EvBox and ChargePoint are looking to radically expand the number of available charging stations, but these plans depend on exponential growth in the sale of EVs. ChargePoint is looking to add 2.5 million charging stations to its global network of just 50,000, a goal it said is based on a “conservative view” of future EV sales. EvBox, meanwhile, is aiming for 1 million new charging stations. A spokesperson noted this target is “at least partly dependent on the number of electric vehicles on the road,” though he was similarly bullish on the growth of EVs. Analysts expect EV sales to increasedramatically in the coming years, though major roadblocks stand in the way of future adoption.

    Even if EV sales take off and charging stations proliferate, barriers will remain. Making EVs more viable means installing not just more chargers, but more fast chargers that allow drivers to take long journeys. The difference between a fast charger and a slow charger is the difference between a family stopping for coffee while they refuel their car and a family stopping overnight.

    A Chargepoint electric vehicle charging station.

     

    “It’s 180 miles from Knoxville to Nashville. Supposedly there’s a [direct current] fast charger at a Cracker Barrel in Cookville, which is almost exactly halfway, but it almost never works,” Greene said. “The fact that the range is limited and the recharging time can be quite long if one does not have access to fast charging, that’s another problem.”

    There is also the fact that the technology isn’t standardized. Different cars use different plugs. Ford and GM use one kind. Tesla uses another. Fast charging requires a different kind altogether. So, while charging stations dot the country, not every station meets every driver’s needs. Until manufacturers arrive at an industry standard — or policymakers mandate that standard —
    “charging stations are going to need to have two or three different types of plugs, and people will need to be able to charge at different speeds because their car might not have a supercharger,” Sifuentes said.

    Sifuentes believes that policymakers have a key role to play in building out charging stations. “They have to actually put in place laws and incentives that encourage the development of the necessary infrastructure, and I think that takes place in two ways,” he said. “One, encouraging utilities to do that. But also, I think we can’t ignore the role that public transit plays here.”

    Different types of EV plugs.

     

    New York City, he said, has pledged to switch to all-electric buses by 2040. “That means they’re going to have to put some serious charging infrastructure in place,” Sifuentes said. “If there’s a charging location that has to be put in because buses need to charge there but that’s available for private use as well, great.”

    In addition to building public charging infrastructure, governments can also encourage the development of private charging infrastructure. Policymakers in Iowa and Austin, Texas, for example, are working to lower barriers to setting up charging stations, allowing private firms, as opposed to power utilities, to resell electricity. “I think the other role that policymakers have to play here is they have to actually put in place laws and incentives that encourage the development of the necessary infrastructure,” Sifuentes said.

    In Norway, where EVs account for around a third of all new car sales, the government has gone a step further. The government is installing a fast charging station every 30 miles on main roads. EV drivers can get free charging at public stations in addition to free parking and free access to toll roads. Sifuentes said these kinds of policies are needed to spur the growth of EVs and support the installation of EV charging stations.

    “We’re absolutely on the tipping point,” Sifeuntes said. “The more that we see EVs rolling out, the more and more it’s going to look like the right move to be putting this infrastructure in place.”

    EV Charge 2 Fastned-solar-powered-EV-charger-NL

    ** Article from EcoWatch

    Visualizing the World’s EV Markets – Who is the World’s Undisputed Leader in EV Adoption?


    It took five years to sell the first million electric cars. In 2018, it took only six months.

    The Tesla Model 3 also passed a significant milestone in 2018, becoming the first electric vehicle (EV) to crack the 100,000 sales mark in a single year. The Nissan LEAF and BAIC EC-Series are both likely to surpass the 100,000 this year as well.

    Although the electric vehicle market didn’t grow as fast as some experts initially projected, it appears that EV sales are finally hitting their stride around the world. Below are the countries where electric vehicles are a biggest part of the sales mix.

    The EV Capital of the World

    Norway, after amassing a fortune through oil and gas extraction, made the conscious decision to create incentives for its citizens to purchase electric vehicles. As a result, the country is the undisputed leader in EV adoption.

    In 2018, a one-third of all passenger vehicles were fully electric, and that percentage is only expected to increase in the near future. The Norwegian government has even set the ambitious target of requiring all new cars to be zero-emission by 2025.

    That enthusiasm for EVs is spilling over to other countries in the region, which are also seeing a high percentage of EV sales. However, the five countries in which EVs are the most popular – Norway, Iceland, Sweden, Netherlands, and Finland – only account for 0.5% of the world’s population. For EV adoption to make any real impact on global emissions, drivers in high-growth/high–population countries will need to opt for electric powered vehicles. (Of course power grids will need to get greener as well, but that’s another topic.)

    China’s Supercharged Impact

    One large economy that is embracing plug-in vehicles is China. 

    The country leads the world in electric vehicle sales, with over a million new vehicles hitting the roads in 2018. Last year, more EVs were sold in Shenzhen and Shanghai than any country in the world, with the exception of the United States.

    China also leads the world in another important metric – charging stations. Not only does China have the highest volume of chargers, many of them allow drivers to charge up faster.

    Electric vehicle charging stations

    Accelerating from the Slow Lane

    In the United States, electric vehicle sales are rising, but they still tend to be highly concentrated in specific areas. In around half of states, EVs account for fewer than 1% of vehicle sales. On the other hand, California is approaching the 10% mark, a significant milestone for the most populous state.

    Nationally, EV sales increasedthroughout 2018, with December registering nearly double the sales volume of the same month in 2017. Part of this surge in sales is driven by the Tesla’s Model 3, which led the market in the last quarter of 2018.

    U.S. Electric vehicle sales

    North of the border, in Canada, the situation is similar. EV sales are increasing, but not fast enough to meet targets set by the government. Canada aimed to have half a million EVs on the road by 2018, but missed that target by around 400,000 vehicles.

    The big question now is whether the recent surge in sales is a temporary trend driven by government subsidies and showmanship of Elon Musk, or whether EVs are now becoming a mainstream option for drivers around the world.

    High Capacity Silicon Anodes Enabled by MXene Viscous Aqueous Ink ~ 2D MXene Nanosheets found to be of Fundamental Importance to Electrochemical Energy Storage Field ~ Trinity College, Dublin


    Mxene for Silcon anodes 41467_2019_8383_Fig2_HTML

    ** Contributed from Nature Communications Open Source Article

     

    The ever-increasing demands for advanced lithium-ion batteries have greatly stimulated the quest for robust electrodes with a high areal capacity. Producing thick electrodes from a high-performance active material would maximize this parameter. However, above a critical thickness, solution-processed films typically encounter electrical/mechanical problems, limiting the achievable areal capacity and rate performance as a result.

    Herein, we show that two-dimensional titanium carbide or carbonitride nano sheets, known as MXenes, can be used as a conductive binder for silicon electrodes produced by a simple and scalable slurry-casting technique without the need of any other additives.

    “The nano sheets form a continuous metallic network, enable fast charge transport and provide good mechanical reinforcement for the thick electrode (up to 450μm). Consequently, very high areal capacity anodes (up to 23.3 mAh cm-2) have been demonstrated.” Utilization of Li-ion chemistry to store the energy electro-chemically can address the ever-increasing demands from both portable electronics and hybrid electrical vehicles.

     

    Such stringent challenges on the battery safety and lifetime issues require high-performance battery components, with most of the focus being on electrodes or electrolytes with novel nano-structures and chemistries.

    However, equally important is the development of electrode additives, which are required to main-tain the electrode’s conductive network and mechanical integrity. Traditionally, electrode additives are made of dual components based on a conductive agent (i.e. carbon black, CB) and a poly-meric binder.

     

    While the former ensures the charge transport throughout the electrode, the latter mechanically holds the active materials and CB together during cycling. Although these traditional electrode additives have been widely applied in Li-ion battery technologies, they fail to perform well in high-capacity electrodes, especially those displaying large volume changes.

    This is because the polymeric binder is not mechanically robust enough to withstand the stress induced during lithiation/deli-thiation, leading to severe disruption of the conducting networks. This results in rapid capacity fade and poor lifetime.

     

    Nature Communications content_content_comms275

     

    Continue Reading the Full Article from Nature Communications

     

     

     

     

    Conclusion

    In summary, the efficient utilization of 2D MXene nanosheets as a new class of conductive binder for high volume-change Si electrodes is of fundamental importance to the electrochemical energy storage field.

    The continuous network of MXene nanosheets not only provides sufficient electrical conductivity and free space for accommodating the volume change issue but also well resolves the mechanical instability of Si. Therefore, the combination of viscous MXene ink and high-capacity Si demonstrated here offers a powerful technique to construct advanced nanostructures with exceptional performance.

    Of equal importance is that the formation of these high-mass-loading Si/MXene electrodes can be achieved by means of a commercially compatible, slurry-casting technique, which is highly scalable and low cost, allowing for large-area production of high-performance, Si-based electrodes for advanced batteries.

    Considering that more than 30 MXenes are already reported, with more predicted to exist, there is certainly much room for further improving the electrochemical performance of such electrodes by tuning the electrical, mechanical and physicochemical properties of this exciting 2D MXene family.

    Professor Valeria Nicolosi Trinity UniversityProfessor Valeria Nicolosi 

    Professor of Nanomaterials and Advanced Microscopy at Trinity College Dublin

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