‘Magnesium Mystery’ for Rechargeable Batteries Solved: DOE



Rechargeable batteries based on magnesium, rather than lithium, have the potential to extend electric vehicle range by packing more energy into smaller batteries. But unforeseen chemical roadblocks have slowed scientific progress.
And the places where solid meets liquid – where the oppositely charged battery electrodes interact with the surrounding chemical mixture known as the electrolyte – are the known problem spots.

Now, a research team at the U.S. Department of Energy’s Joint Center for Energy Storage Research, led by scientists at Lawrence Berkeley National Laboratory (Berkeley Lab), has discovered a surprising set of chemical reactions involving magnesium that degrade battery performance even before the battery can be charged up.

The findings could be relevant to other battery materials, and could steer the design of next-generation batteries toward workarounds that avoid these newly identified pitfalls.

The team used X-ray experiments, theoretical modeling, and supercomputer simulations to develop a full understanding of the chemical breakdown of a liquid electrolyte occurring within tens of nanometers of an electrode surface that degrades battery performance. Their findings are published online in the journal Chemistry of Materials (“Instability at the Electrode/Electrolyte Interface Induced by Hard Cation Chelation and Nucleophilic Attack”).

The battery they were testing featured magnesium metal as its negative electrode (the anode) in contact with an electrolyte composed of a liquid (a type of solvent known as diglyme) and a dissolved salt, Mg(TFSI)2.

While the combination of materials they used were believed to be compatible and nonreactive in the battery’s resting state, experiments at Berkeley Lab’s Advanced Light Source (ALS), an X-ray source called a synchrotron, uncovered that this is not the case and led the study in new directions.


Posted: Oct 19, 2017

Scientists solve a magnesium mystery in rechargeable battery performance

(Nanowerk News) Rechargeable batteries based on magnesium, rather than lithium, have the potential to extend electric vehicle range by packing more energy into smaller batteries. But unforeseen chemical roadblocks have slowed scientific progress.

And the places where solid meets liquid – where the oppositely charged battery electrodes interact with the surrounding chemical mixture known as the electrolyte – are the known problem spots.

Now, a research team at the U.S. Department of Energy’s Joint Center for Energy Storage Research, led by scientists at Lawrence Berkeley National Laboratory (Berkeley Lab), has discovered a surprising set of chemical reactions involving magnesium that degrade battery performance even before the battery can be charged up.

The findings could be relevant to other battery materials, and could steer the design of next-generation batteries toward workarounds that avoid these newly identified pitfalls.

The team used X-ray experiments, theoretical modeling, and supercomputer simulations to develop a full understanding of the chemical breakdown of a liquid electrolyte occurring within tens of nanometers of an electrode surface that degrades battery performance. Their findings are published online in the journal Chemistry of Materials (“Instability at the Electrode/Electrolyte Interface Induced by Hard Cation Chelation and Nucleophilic Attack”).

The battery they were testing featured magnesium metal as its negative electrode (the anode) in contact with an electrolyte composed of a liquid (a type of solvent known as diglyme) and a dissolved salt, Mg(TFSI)2.

While the combination of materials they used were believed to be compatible and nonreactive in the battery’s resting state, experiments at Berkeley Lab’s Advanced Light Source (ALS), an X-ray source called a synchrotron, uncovered that this is not the case and led the study in new directions.

molecular models shows the initial state of battery chemistry that leads to instability in a test cell featuring a magnesium anode

These molecular models show the initial state of battery chemistry that leads to instability in a test cell featuring a magnesium (Mg) anode. (Credit: Berkeley Lab)

“People had thought the problems with these materials occurred during the battery’s charging, but instead the experiments indicated that there was already some activity,” said David Prendergast, who directs the Theory of Nanostructured Materials Facility at the Molecular Foundry and served as one of the study’s leaders.

“At that point it got very interesting,” he said. “What could possibly cause these reactions between substances that are supposed to be stable under these conditions?”

Molecular Foundry researchers developed detailed simulations of the point where the electrode and electrolyte meet, known as the interface, indicating that no spontaneous chemical reactions should occur under ideal conditions, either. The simulations, though, did not account for all of the chemical details.

“Prior to our investigations,” said Ethan Crumlin, an ALS scientist who coordinated the X-ray experiments and co-led the study with Prendergast, “there were suspicions about the behavior of these materials and possible connections to poor battery performance, but they hadn’t been confirmed in a working battery.”

Commercially popular lithium-ion batteries, which power many portable electronic devices (such as mobile phones, laptops, and power tools) and a growing fleet of electric vehicles, shuttle lithium ions – lithium atoms that become charged by shedding an electron – back and forth between the two battery electrodes. These electrode materials are porous at the atomic scale and are alternatively loaded up or emptied of lithium ions as the battery is charged or discharged.

In this type of battery, the negative electrode is typically composed of carbon, which has a more limited capacity for storing these lithium ions than other materials would.

So increasing the density of stored lithium by using another material would make for lighter, smaller, more powerful batteries. Using lithium metal in the electrode, for example, can pack in more lithium ions in the same space, though it is a highly reactive substance that burns when exposed to air, and requires further research on how to best package and protect it for long-term stability.

Magnesium metal has a higher energy density than lithium metal, meaning you can potentially store more energy in a battery of the same size if you use magnesium rather than lithium.

Magnesium is also more stable than lithium. Its surface forms a self-protecting “oxidized” layer as it reacts with moisture and oxygen in the air. But within a battery, this oxidized layer is believed to reduce efficiency and shorten battery life, so researchers are looking for ways to avoid its formation.

To explore the formation of this layer in more detail, the team employed a unique X-ray technique developed recently at the ALS, called APXPS (ambient pressure X-ray photoelectron spectroscopy). This new technique is sensitive to the chemistry occurring at the interface of a solid and liquid, which makes it an ideal tool to explore battery chemistry at the surface of the electrode, where it meets the liquid electrolyte.

Simulations show the weakening of a bond in a liquid solvent due to the presence of free-floating hydroxide ions

Simulations show the weakening of a bond in a liquid solvent due to the presence of free-floating hydroxide ions, which contain a single oxygen atom bound to a hydrogen atom. In this illustration, atoms are color-coded: hydrogen (white), oxygen (red), carbon (light blue), magnesium (green), nitrogen (dark blue), sulfur (yellow), fluorine (brown). This process degrades battery performance. (Credit: Berkeley Lab)

Even before a current was fed into the test battery, the X-ray results showed signs of chemical decomposition of the electrolyte, specifically at the interface of the magnesium electrode. The findings forced researchers to rethink their molecular-scale picture of these materials and how they interact.

What they determined is that the self-stabilizing, thin oxide surface layer that forms on the magnesium has defects and impurities that drive unwanted reactions.

“It’s not the metal itself, or its oxides, that are a problem,” Prendergast said. “It’s the fact you can have imperfections in the oxidized surface. These little disparities become sites for reactions. It feeds itself in this way.”

A further round of simulations, which proposed possible defects in the oxidized magnesium surface, showed that defects in the oxidized surface layer of the anode can expose magnesium ions that then act as traps for the electrolyte’s molecules.

If free-floating hydroxide ions – molecules containing a single oxygen atom bound to a hydrogen atom that can be formed as trace amounts of water react with the magnesium metal – meet these surface-bound molecules, they will react.

This wastes electrolyte, drying out the battery over time. And the products of these reactions foul the anode’s surface, impairing the battery’s function.

It took several iterations back and forth, between the experimental and theoretical members of the team, to develop a model consistent with the X-ray measurements. The efforts were supported by millions of hours’ worth of computing power at the Lab’s National Energy Research Scientific Computing Center.

Researchers noted the importance of having access to X-ray techniques, nanoscale expertise, and computing resources at the same Lab.

The results could be relevant to other types of battery materials, too, including prototypes based on lithium or aluminum metal. Prendergast said, “This could be a more general phenomenon defining electrolyte stability.”

Crumlin added, “We’ve already started running new simulations that could show us how to modify the electrolyte to reduce the instability of these reactions.” Likewise, he said, it may be possible to tailor the surface of the magnesium to reduce or eliminate some of the unwanted chemical reactivity.

“Rather than allowing it to create its own interface, you could construct it yourself to control and stabilize the interface chemistry,” he added. “Right now it leads to uncontrollable events.”

Source: By Glenn Roberts Jr., Lawrence Berkeley National Laboratory

These molecular models show the initial state of battery chemistry that leads to instability in a test cell featuring a magnesium (Mg) anode. (Credit: Berkeley Lab)

“People had thought the problems with these materials occurred during the battery’s charging, but instead the experiments indicated that there was already some activity,” said David Prendergast, who directs the Theory of Nanostructured Materials Facility at the Molecular Foundry and served as one of the study’s leaders.

“At that point it got very interesting,” he said. “What could possibly cause these reactions between substances that are supposed to be stable under these conditions?”

Molecular Foundry researchers developed detailed simulations of the point where the electrode and electrolyte meet, known as the interface, indicating that no spontaneous chemical reactions should occur under ideal conditions, either. The simulations, though, did not account for all of the chemical details.

“Prior to our investigations,” said Ethan Crumlin, an ALS scientist who coordinated the X-ray experiments and co-led the study with Prendergast, “there were suspicions about the behavior of these materials and possible connections to poor battery performance, but they hadn’t been confirmed in a working battery.”

Commercially popular lithium-ion batteries, which power many portable electronic devices (such as mobile phones, laptops, and power tools) and a growing fleet of electric vehicles, shuttle lithium ions – lithium atoms that become charged by shedding an electron – back and forth between the two battery electrodes. These electrode materials are porous at the atomic scale and are alternatively loaded up or emptied of lithium ions as the battery is charged or discharged.

In this type of battery, the negative electrode is typically composed of carbon, which has a more limited capacity for storing these lithium ions than other materials would.

So increasing the density of stored lithium by using another material would make for lighter, smaller, more powerful batteries. Using lithium metal in the electrode, for example, can pack in more lithium ions in the same space, though it is a highly reactive substance that burns when exposed to air, and requires further research on how to best package and protect it for long-term stability.

Magnesium metal has a higher energy density than lithium metal, meaning you can potentially store more energy in a battery of the same size if you use magnesium rather than lithium.

Magnesium is also more stable than lithium. Its surface forms a self-protecting “oxidized” layer as it reacts with moisture and oxygen in the air. But within a battery, this oxidized layer is believed to reduce efficiency and shorten battery life, so researchers are looking for ways to avoid its formation.

To explore the formation of this layer in more detail, the team employed a unique X-ray technique developed recently at the ALS, called APXPS (ambient pressure X-ray photoelectron spectroscopy). This new technique is sensitive to the chemistry occurring at the interface of a solid and liquid, which makes it an ideal tool to explore battery chemistry at the surface of the electrode, where it meets the liquid electrolyte.

Simulations show the weakening of a bond in a liquid solvent due to the presence of free-floating hydroxide ions

Simulations show the weakening of a bond in a liquid solvent due to the presence of free-floating hydroxide ions, which contain a single oxygen atom bound to a hydrogen atom. In this illustration, atoms are color-coded: hydrogen (white), oxygen (red), carbon (light blue), magnesium (green), nitrogen (dark blue), sulfur (yellow), fluorine (brown). This process degrades battery performance. (Credit: Berkeley Lab)

Even before a current was fed into the test battery, the X-ray results showed signs of chemical decomposition of the electrolyte, specifically at the interface of the magnesium electrode. The findings forced researchers to rethink their molecular-scale picture of these materials and how they interact.

What they determined is that the self-stabilizing, thin oxide surface layer that forms on the magnesium has defects and impurities that drive unwanted reactions.

“It’s not the metal itself, or its oxides, that are a problem,” Prendergast said. “It’s the fact you can have imperfections in the oxidized surface. These little disparities become sites for reactions. It feeds itself in this way.”

A further round of simulations, which proposed possible defects in the oxidized magnesium surface, showed that defects in the oxidized surface layer of the anode can expose magnesium ions that then act as traps for the electrolyte’s molecules.

If free-floating hydroxide ions – molecules containing a single oxygen atom bound to a hydrogen atom that can be formed as trace amounts of water react with the magnesium metal – meet these surface-bound molecules, they will react.

This wastes electrolyte, drying out the battery over time. And the products of these reactions foul the anode’s surface, impairing the battery’s function.

It took several iterations back and forth, between the experimental and theoretical members of the team, to develop a model consistent with the X-ray measurements. The efforts were supported by millions of hours’ worth of computing power at the Lab’s National Energy Research Scientific Computing Center.

Researchers noted the importance of having access to X-ray techniques, nanoscale expertise, and computing resources at the same Lab.

The results could be relevant to other types of battery materials, too, including prototypes based on lithium or aluminum metal. Prendergast said, “This could be a more general phenomenon defining electrolyte stability.”

Crumlin added, “We’ve already started running new simulations that could show us how to modify the electrolyte to reduce the instability of these reactions.” Likewise, he said, it may be possible to tailor the surface of the magnesium to reduce or eliminate some of the unwanted chemical reactivity.

“Rather than allowing it to create its own interface, you could construct it yourself to control and stabilize the interface chemistry,” he added. “Right now it leads to uncontrollable events.”

Source: By Glenn Roberts Jr., Lawrence Berkeley National Laboratory

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NREL Reports: Plug-In EV’s and the ‘Charging Infrastructure’ Needed to Support Them


How much vehicle charging infrastructure is needed in the United States to support broader adoption scenarios for various types of plug-in electric vehicles?

 

 
A new report by NREL for the U.S. Department of Energy takes a look, providing guidance to public and private stakeholders seeking a nationwide network of non-residential (public and workplace) vehicle charging infrastructure.

See the full report at: http://bit.ly/2xWVfjh

 

 

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Clemson University team’s graphene-enhanced aluminum-ion batteries outperform lithium-ion ones


Oct 19, 2017

Clemson’s graphene-enhanced aluminum ion batteries outperform Li-ion ones image



Researchers at Clemson University in the U.S have shown that replacing lithium with aluminum and graphene may be key for next-gen batteries.

Aluminum is regarded as non-toxic and much more plentiful than the lithium currently in widespread use (and cheaper). Aluminum also transfers energy more efficiently. Inside a battery, the element — lithium or aluminum — gives up some of its electrons, which flow through external wires to power a device.

Because of their atomic structure, lithium ions can only provide one electron at a time; aluminum can give three at a time. That, the team says, is the real point of the switch.
Still, aluminum ion batteries designed by other researchers have not performed as well as lithium ion batteries.

The Clemson team describes how they were able to get aluminum ion to perform better than previously tested aluminum ion batteries. “The problem isn’t that aluminum ions are deficient,” said a graduate student at the Clemson Nanomaterials Institute and the first author of the Nano Energy paper. 

It’s that unlike lithium ions that have been around for a while, we do not know much about how aluminum ions behave inside the battery.”


Material Matters

The electrode in a battery is like a bucket and the electrical charge is like sand inside the bucket. If the sand starts to flow out, the speed at which it flows is the current. The greater the speed (the larger the current) the quicker the bucket is empty and the sooner the battery goes flat. The more sand you store in the bucket, the longer the current lasts.

The Clemson team seems to have found a way to pack more sand in the bucket and used tools to confirm the bucket was full. Their new battery technology uses aluminum foil and few-layer graphene as the electrode to store electrical charge from aluminum ions present in the electrolyte.

“We knew that aluminum ions could be stored inside few-layer graphene,” the team said. “But the ions need to be packed efficiently to increase the battery capacity. The arrangement of aluminum ions inside graphene is critical for better battery performance.”

“These aluminum batteries can last more than 10,000 cycles without any performance loss,” the researchers said. “Our hope is to make aluminum batteries with higher energy to ultimately displace lithium-ion technology.”
The next step toward a commercially viable aluminum ion battery is lowering the cost. Although aluminum is relatively inexpensive, the electrolytes are pricey.

Source:  Clemson

NREL: Demonstrating and Advancing Benefits of Hydrogen Technology



by Bryan S. Pivovar, Ph.D, H2@Scale Lead/Group Manager, Chemistry and Nanosciences Center, National Renewable Energy Laboratory

Over the past several decades, technological advancements and cost reductions have dramatically changed the economic potential of hydrogen in our energy system. 
Fuel cell electric vehicles are now available for commercial sale and hydrogen stations are open to the public (more than 2,000 fuel cell vehicles are on the road and more than 30 fueling stations are open to the public in California). 

Low-cost wind and solar power are quickly changing the power generation landscape and creating a need for technologies that enhance the flexibility of the grid in the mid- to long-term.

The vision of a clean, sustainable energy system with hydrogen serving as the critical centerpiece is the focus of H2@Scale, a major initiative involving multiple U.S. Department of Energy (DOE) program offices, led by DOE’s Fuel Cell Technologies Office in the Office of Energy Efficiency and Renewable Energy, and 14 DOE national laboratories. 

H2@Scale expands the focus of hydrogen technologies beyond power generation and transportation, to grid services and industrial processes that use hydrogen.

The Energy Systems Integration Facility (ESIF) at the National Renewable Energy Laboratory (NREL) serves as a world-class, sophisticated testbed to evaluate and advance the H2@Scale concept. 

The ESIF is a DOE user facility interacting with multiple industrial stakeholders to accelerate the adoption of clean energy, including hydrogen-based technologies. Many of the barriers for making the H2@Scale vision a reality are being addressed today within ESIF by NREL researchers along with other industrial and national laboratory collaborators. 

The unique testbed capabilities at NREL and collaborating national labs are now available for use by industry and several partnerships are currently in development.
Within the ESIF, NREL researchers use electrons and water to produce hydrogen at rates of up to 100 kg/day (enough to fuel ~6,000 miles of travel in today’s fuel cell electric vehicles or more than 20 cars) with plans to expand capacity to four times this level. 

The hydrogen produced is compressed and stored in the 350 kg of on-site storage available at pressures as high as 12,500 psi. The hydrogen is used in multiple applications at the ESIF, including fueling fuel cell electric vehicles, testing and validating hydrogen infrastructure components and systems, producing renewable natural gas (through biological reaction with carbon dioxide), and as a feedstock for fuel cell power generation and research and development efforts.

To accelerate the H2@Scale concept, the cost, performance, and durability of hydrogen production, infrastructure (distribution and storage), and end use technologies need to be improved. NREL researchers, along with other labs, are actively demonstrating and advancing hydrogen technology in a number of areas including low-temperature electrolysis, biological production of renewable natural gas, and infrastructure.

Renewable hydrogen via low-temperature electrolysis




Today’s small-scale electrolysis systems are capable of producing several kilograms (kg) of hydrogen per day, but can cost as much as $10 per watt. At larger scale, megawatt (MW) systems producing more than 400 kg per day can cost under $2 per watt. However, for low-temperature electrolyzer systems to compete with the established steam methane reforming process for hydrogen production, the capital cost needs to be reduced to far below $1 per watt.

NREL has ongoing collaborations with Idaho National Laboratory (INL) to demonstrate control of a 250-kW electrolyzer system in a real-time grid simulation using a hardware-in-the-loop (HIL)-based approach to verify the performance of electrolyzer systems in providing grid support. HIL couples modeling and hardware in real-time simulations to better understand the performance of complex systems. 

The electrolyzer system, a building block for megawatt-scale deployment, was remotely controlled based on simulations of signals from a power grid. NREL and INL engineers demonstrated the ability of an electrolyzer to respond to grid signals in sub-seconds, making electrolyzers a viable candidate for “demand response” technologies that help control frequency and voltage on the grid by adjusting their power intake based on grid signals. 

A key enabler of low-cost electrolysis will be for electrolyzer technologies to respond dynamically to grid signals, such that they access low-cost power when available. The potential performance and durability implications of such dynamic operation are being elucidated in ongoing tests. Such experiments are essential to assess the potential for electrolyzers to support grid resiliency and to identify remaining R&D needs toward this value proposition.
NREL’s scientists are developing and exploring new materials for electrolysis systems, including advanced catalysts based on nanowire architecture and alkaline membranes, and approaches for integrating these materials into low-cost, durable membrane electrode assemblies.  

Antibiotics dosed with quantum dots appear to be better at killing superbugs



A researcher holds up a device used to test “super” bacteria’s ability to growth in the presence of antibiotics.CDC

Scientists have used quantum dots activated by light to help antibiotics fight bacteria more effectively. This could be a powerful new tool in the fight against antibiotic-resistant infections.

Quantum dots

Quantum dots, currently used in place of organic dyes in various experiments using photo-electronics to trace the ways that drugs and other molecules move through the body, may have a new supportive role in healthcare.

Scientists have engineered quantum dot nanoparticles that produce chemicals that can make bacteria more vulnerable to antibiotics. This will hopefully be a step forward in the fight against drug-resistant pathogens, like superbugs, and the infections they cause.

In this study, antibiotics empowered by the experimental quantum dots were 1,000 times more effective at fighting off bacteria than antibiotics alone. The quantum dots used were about the width of a strand of DNA, 3 nanometers in diameter. The dots were made of cadmium telluride, a stable crystalline compound often used in photovoltaics.

The electrons of the quantum dots react to green light at a particular frequency, causing them to bond with oxygen molecules in the body and form superoxide. Bacteria that absorbs the substance are unable to fend off antibiotics, as their internal chemistry falls out of balance.

The team mixed different quantities of quantum dots into varying concentrations of each of five antibiotics to create the range of samples for testing. They then added these test samples to five strains of drug-resistant bacteria, including methicillin-resistant Staphylococcus aureus, also known as MRSA, and Salmonella.

In the 480 tests with different quantum dots/antibiotics/bacteria combinations, more than 75 percent of the samples with quantum dots were able to curb bacterial growth or kill the bacteria entirely with lower doses of antibiotics.

Antibiotic resistance is becoming a growing problem considering how fast bacteria is adapting to medication.Getty Images/Joe Raedle

Antibiotic resistance



According to the World Health Organization (WHO), antibiotic resistance is among the most serious threats to food security, health, and development in the world. It can affect anyone in any country, and infections like gonorrhea, pneumonia, and tuberculosis thar were once simple to treat are now becoming increasingly difficult to manage due to antibiotic resistance.

Aside from obvious health and even mortality risks, antibiotic resistance also causes higher medical costs and longer hospital stays. And, although some level of antibiotic resistance occurs naturally as bacteria adapt to survive, misuse of antibiotics in both animals and humans is drastically accelerating this process.


In the US alone, at least 2 million people are affected by antibiotic resistance every year. And, if nothing is done to combat this problem, by 2050 antibiotic resistance will kill more than 10 million people. 

Researchers are working on a variety of techniques to overcome this challenge. Some are using CRISPR to attack the bacteria directly, while others are looking for answers by studying the ways that ants battle detrimental fungi. Meanwhile, scientists are searching for the genetic origins of antibiotic resistance and some are even battling resistance by studying the ways bacteria behave in space.

One limitation of this study’s use of quantum dots is the light that activates the process; it has to come from somewhere, and it can only radiate through a few millimeters of flesh.

For now, these quantum dots would really only be useful for surface issues. However, the team is also working to develop nanoparticles that absorb infrared light instead, as infrared light can pass through the body and could be used to treat bone and deep tissue infections.

 

Paper-based Supercapacitor uses metal Nanoparticles to Boost Energy Density


GIT Paper SuperCap 171005121053_1_540x360Images show the difference between paper prior to metallization (left) and the paper coated with conductive nanoparticles. Credit: Ko et al., published in Nature Communications

Using a simple layer-by-layer coating technique, researchers from the U.S. and Korea have developed a paper-based flexible supercapacitor that could be used to help power wearable devices. The device uses metallic nanoparticles to coat cellulose fibers in the paper, creating supercapacitor electrodes with high energy and power densities — and the best performance so far in a textile-based supercapacitor.

By implanting conductive and charge storage materials in the paper, the technique creates large surface areas that function as current collectors and nanoparticle reservoirs for the electrodes. Testing shows that devices fabricated with the technique can be folded thousands of times without affecting conductivity.

“This type of flexible energy storage device could provide unique opportunities for connectivity among wearable and internet of things devices,” said Seung Woo Lee, an assistant professor in the Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. “We could support an evolution of the most advanced portable electronics. We also have an opportunity to combine this supercapacitor with energy-harvesting devices that could power biomedical sensors, consumer and military electronics, and similar applications.”

The research, done with collaborators at Korea University, was supported by the National Research Foundation of Korea and reported September 14 in the journal Nature Communications.

Energy storage devices are generally judged on three properties: their energy density, power density and cycling stability. Supercapacitors often have high power density, but low energy density — the amount of energy that can be stored — compared to batteries, which often have the opposite attributes. In developing their new technique, Lee and collaborator Jinhan Cho from the Department of Chemical and Biological Engineering at Korea University set out to boost energy density of the supercapacitors while maintaining their high power output.

The researchers began by dipping paper samples into a beaker of solution containing an amine surfactant material designed to bind the gold nanoparticles to the paper. Next they dipped the paper into a solution containing gold nanoparticles. Because the fibers are porous, the surfactants and nanoparticles enter the fibers and become strongly attached, creating a conformal coating on each fiber.

By repeating the dipping steps, the researchers created a conductive paper on which they added alternating layers of metal oxide energy storage materials such as manganese oxide. The ligand-mediated layer-by-layer approach helped minimize the contact resistance between neighboring metal and/or metal oxide nanonparticles. Using the simple process done at room temperatures, the layers can be built up to provide the desired electrical properties.

“It’s basically a very simple process,” Lee said. “The layer-by-layer process, which we did in alternating beakers, provides a good conformal coating on the cellulose fibers. We can fold the resulting metallized paper and otherwise flex it without damage to the conductivity.”

Though the research involved small samples of paper, the solution-based technique could likely be scaled up using larger tanks or even a spray-on technique. “There should be no limitation on the size of the samples that we could produce,” Lee said. “We just need to establish the optimal layer thickness that provides good conductivity while minimizing the use of the nanoparticles to optimize the tradeoff between cost and performance.”

The researchers demonstrated that their self-assembly technique improves several aspects of the paper supercapacitor, including its areal performance, an important factor for measuring flexible energy-storage electrodes. The maximum power and energy density of the metallic paper-based supercapacitors are estimated to be 15.1mWcm?2 and 267.3 ?Wh cm?2, respectively, substantially outperforming conventional paper or textile supercapacitors.

The next steps will include testing the technique on flexible fabrics, and developing flexible batteries that could work with the supercapacitors. The researchers used gold nanoparticles because they are easy to work with, but plan to test less expensive metals such as silver and copper to reduce the cost.

During his Ph.D. work, Lee developed the layer-by-layer self-assembly process for energy storage using different materials. With his Korean collaborators, he saw a new opportunity to apply that to flexible and wearable devices with nanoparticles.

“We have nanoscale control over the coating applied to the paper,” he added. “If we increase the number of layers, the performance continues to increase. And it’s all based on ordinary paper.”

Story Source:

Materials provided by Georgia Institute of TechnologyNote: Content may be edited for style and length.


Journal Reference:

  1. Yongmin Ko, Minseong Kwon, Wan Ki Bae, Byeongyong Lee, Seung Woo Lee, Jinhan Cho. Flexible supercapacitor electrodes based on real metal-like cellulose papersNature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-00550-3

Light-activated Nanoparticles (Quantum Dots) can supercharge current antibiotics


QDs and Antibiotics CU 171004142650_1_540x360CU Boulder researcher Colleen Courtney (left) speaks with Assistant Professor Anushree Chatterjee (right) inside a lab in the BioFrontiers Institute.
Credit: University of Colorado Boulder

Light-activated nanoparticles, also known as quantum dots, can provide a crucial boost in effectiveness for antibiotic treatments used to combat drug-resistant superbugs such as E. coliand Salmonella, new University of Colorado Boulder research shows.

Multi-drug resistant pathogens, which evolve their defenses faster than new antibiotic treatments can be developed to treat them, cost the United States an estimated $20 billion in direct healthcare costs and an additional $35 billion in lost productivity in 2013.

CU Boulder researchers, however, were able to re-potentiate existing antibiotics for certain clinical isolate infections by introducing nano-engineered quantum dots, which can be deployed selectively and activated or de-activated using specific wavelengths of light.

Rather than attacking the infecting bacteria conventionally, the dots release superoxide, a chemical species that interferes with the bacteria’s metabolic and cellular processes, triggering a fight response that makes it more susceptible to the original antibiotic.

“We’ve developed a one-two knockout punch,” said Prashant Nagpal, an assistant professor in CU Boulder’s Department of Chemical and Biological Engineering (CHBE) and the co-lead author of the study. “The bacteria’s natural fight reaction [to the dots] actually leaves it more vulnerable.”

The findings, which were published today in the journal Science Advances, show that the dots reduced the effective antibiotic resistance of the clinical isolate infections by a factor of 1,000 without producing adverse side effects.

“We are thinking more like the bug,” said Anushree Chatterjee, an assistant professor in CHBE and the co-lead author of the study. “This is a novel strategy that plays against the infection’s normal strength and catalyzes the antibiotic instead.”

While other previous antibiotic treatments have proven too indiscriminate in their attack, the quantum dots have the advantage of being able to work selectively on an intracellular level. Salmonella, for example, can grow and reproduce inside host cells. The dots, however, are small enough to slip inside and help clear the infection from within.

“These super-resistant bugs already exist right now, especially in hospitals,” said Nagpal. “It’s just a matter of not contracting them. But they are one mutation away from becoming much more widespread infections.”

Overall, Chatterjee said, the most important advantage of the quantum dot technology is that it offers clinicians an adaptable multifaceted approach to fighting infections that are already straining the limits of current treatments.

“Disease works much faster than we do,” she said. “Medicine needs to evolve as well.”

Going forward, the researchers envision quantum dots as a kind of platform technology that can be scaled and modified to combat a wide range of infections and potentially expand to other therapeutic applications.

Story Source:

Materials provided by University of Colorado at Boulder. Original written by Trent Knoss. Note: Content may be edited for style and length.


Journal Reference:

  1. Colleen M. Courtney, Samuel M. Goodman, Toni A. Nagy, Max Levy, Pallavi Bhusal, Nancy E. Madinger, Corrella S. Detweiler, Prashant Nagpal, and Anushree Chatterjee. Potentiating antibiotics in drug-resistant clinical isolates via stimuli-activated superoxide generationScience Advances, 04 Oct 2017 DOI: 10.1126/sciadv.1701776

Tesla wants to build special charging stations that sell food and coffee — and it could be a huge opportunity … Or NOT!


 

Tesla wants to build special charging stations that sell food and coffee — and it could be a huge opportunity

Tesla Coffee – I’ll have a cup of Musk’s Blend – Business Insider

• Tesla is planning to build more retail-and-lifestyle focused “Mega Supercharger locations.”
• This might tempt the company to partner with the Amazons and Starbucks of the world.
• IOHO – That would be a big mistake!

As Tesla expands its Supercharger network, the automaker intends to up its game, building higher-end, retail-rich locations that CEO Elon Musk has called “Mega Superchargers” but that we’ll call just Megachargers.

CEO Elon Musk has speculatively described them as “like really big supercharging locations with a bunch of amenities,” complete with “great restrooms, great food, amenities” and an awesome place to “hang out for half an hour and then be on your way.”


The move makes sense. 



Superchargers are currently located through the US and other countries, providing the fastest rate of recharging available to Tesla owners. The station can have varying numbers of charging stalls, however, and they aren’t always located in the best areas for passing the time while a Tesla inhales new electrons, although Tesla typically tries to construct them near retail and dining options.

With more Tesla hitting the road in coming years as more and more Model 3 sedans are delivered (Tesla has about 500,000 pre-orders for the car, priced from $35,000-$44,000), additional Superchargers will be needed. Creating stand-alone Megachargers that function sort of like Tesla stores would enhance the ownership experience — and open new opportunities to the company.

At Business Insider, when we heard about the Megachargers, a discussion broke out. Should Tesla partner with Amazon or Starbucks to develop these locations, offering great shopping, food, and above all else … coffee?

Bring on the Tesla Brew


A Starbucks store is seen inside the Tom Bradley terminal at LAX airport in Los Angeles, California, United States, October 27, 2015. REUTERS/Lucy Nicholson      

Don’t do it, Tesla!Thomson Reuters I insisted, “NO NO NO!”
There’s no way that Tesla can blow the chance to create its own coffee. They could call it “Elon’s Blend” — bold, complex flavors, with a hint of, um, musk.

In all seriousness, for Tesla to share its Megacharger commerce might sound great, but it wouldn’t fit with the company’s plan to move toward greater vertical integration, owning not just the entire manufacturing process for its cars but also controlling its brand experience from top to bottom.

A recent example of Tesla’s reluctance to partner for the sake of partnering was the announcement that the carmaker could be working on its own streaming service. There are other instances that aren’t as obvious. Tesla’s audio system is an in-house design, a departure from what most luxury automaker do, which is joined with a well-known premium audio brands such as Bose or Bowers & Wilkins.

The company is already focused on building its own vehicle components, ranging from the guts of its cars — the battery packs and drivetrains — to seats and, of course, software. 

For a huge automaker, this type of integration can be impractical, but at Tesla’s current size, its business model operates more like Ford’s or GM’s did back before World War II, when near-total vertical integration was an advantage.


Supercharging is fun — and could be more fun!

In this respect, I’m using Tesla Brew as a symbolic bit of humor: it’s not entirely logical for Tesla to give away any branding opportunity that bolsters its existing and future owners’ perception that the Tesla experience is unique, self-contained, and dramatically different from what other carmakers are selling.

The Megachargers, if they’re built, are going to have a significant effect on how the overall Tesla experience is enjoyed. At the moment, the Supercharger network is pretty far-flung.

But Tesla wants to locate more fast-charging stations along the routes owners are likely to travel, so you could end up in a nice retail location just as easily as you could an out-of-the-way venue where there isn’t much to do besides consider some fast-food options.

There’s nothing inherently wrong with that, but Tesla is a premium brand and for the most part, presents itself accordingly. You don’t find Tesla stores in odd places; you find them in upscale urban areas.

Tesla has endured its problems, but marketing isn’t one of them. Musk and his team might not yet have delivered 100,000 vehicles in a full year, but they’ve delivered almost that — with no advertising whatsoever. In the car world, 
Tesla ranks with Ferrari in terms of its aspirational aspects, and outside the car world, one thinks immediately of Apple. In the retail realm, Starbucks pops to mind, and that in itself is reason enough for Tesla to avoid putting the Green Siren next to its logo at Megacharger locations. 

If you’re a little bit cynical about Tesla, you might argue that the company is much better at marketing than it is at the whole car thing, and you’d be right. However, few people get excited about Ford- or Toyota-branded products that aren’t cars, and even Ferrari-branded merchandise isn’t always coveted, something that Ferrari, now a public company, is trying to change.

Tesla is already a luxury, and with an added high-tech, save-the-planet edge to everything. It’s begun the remaking of transportation. It could now be time to remake coffee, too. 

Tiny Nanoparticles Could Help Repair Damaged Brain And Nerve Cells


brain-quantum-1-download (1)

When our brains develop problems, such as degenerative diseases or epilepsy, some of the trouble can be electrical. As nerve signals involve electrically charged particles moving around, medics often try to treat associated problems using implanted electrodes. But this is a clumsy and difficult approach. A much better idea could be to implant tiny structures deep in the brain to act almost as miniature electricians. It may sound like science fiction, but it is moving fast towards reality.

Attilio Marino and colleagues at the Smart Bio-Interfaces group at the Italian Institute of Technology in Pontedera are striving to bring the idea to the clinic. They summarise progress in the field in a news and opinions article in Nano Today.brain_header

Nanomaterials are showing great potential in biomedicine since they can interact precisely with living systems down to the level of cells, subcellular structures and even individual molecules,” says Marino.

Marino is most interested in ‘piezoelectric‘ materials, which can convert mechanical stimulation into electrical energy, or vice-versa. He is exploring using ultrasound to mechanically stimulate nanoparticles into creating electrical signals that may fix problems with brain cells.

He points out that ultrasound offers a way to get a signal deep into brain tissue without using invasive electrodes, which can cause other problems including inflammation. Some researchers try to get round these difficulties using stimulation with light, but light cannot penetrate very deeply so ultrasound is a better option.

The field is still in its early days. Researchers are mainly studying the effects of piezoelectric nanoparticles on cultured cells rather than in animals or people, but the results are promising. Marino’s team, for example, shows that using ultrasound to stimulate nanoparticles embedded in nerve cells can increase the sprouting of new cell-signalling appendages called axons. This is exactly the kind of effect that may one day repair degenerative brain disease.

“We used barium titanate nanoparticles and confirmed the effect was specifically due to the piezoelectricity of our materials,” says Marino.

Other researchers are working with the ‘stem cells‘ that can develop into a wide range of mature types of cell needed by the body. Some are finding that piezoelectric nanomaterials can stimulate stem cells to begin their transformation into a variety of functional cell types.

A long road of safety studies, animal tests and eventual clinical trials lies ahead. But Marino is optimistic, he concludes: “The preliminary successes strongly encourage us that our research is a realistic approach for use in clinical practice in the near future.”


You can read the article for free for a limited time:

Marino, A., et al.: “Piezoelectric nanotransducers: The future of neural stimulation,” Nano Today (2017)

Better photovoltaic efficiency grows from enormous solar crystals: MH Perovskites 


In-depth analysis of the mechanisms that generate floating crystals from hot liquids could lead to large-scale, printable solar cells


New evidence of surface-initiated crystallization may improve the efficiency of printable photovoltaic materials.

In the race to replace silicon in low-cost solar cells, semiconductors known as metal halide perovskites are favored because they can be solution-processed into thin films with excellent photovoltaic efficiency. 

A collaboration between King Abdullah University of Science and Technology (KAUST) and Oxford University researchers has now uncovered a strategy that grows perovskites into centimeter-scale, highly pure crystals thanks to the effect of surface tension (ACS Energy Letters, “The role of surface tension in the crystallization of metal halide perovskites”).

In their natural state, perovskites have difficultly moving solar-generated electricity because they crystallize with randomly oriented grains. 

Osman Bakr from KAUST’s Solar Center and coworkers are working on ways to dramatically speed up the flow of these charge carriers using inverse temperature crystallization (ITC). This technique uses special organic liquids and thermal energy to force perovskites to solidify into structures resembling single crystals—the optimal arrangements for device purposes.

While ITC produces high-quality perovskites far faster than conventional chemical methods, the curious mechanisms that initiate crystallization in hot organic liquids are poorly understood. Ayan Zhumekenov, a PhD student in Bakr’s group, recalls spotting a key piece of evidence during efforts to adapt ITC toward large-scale manufacturing. “At some point, we realized that when crystals appeared, it was usually at the solution’s surface,” he says. “And this was particularly true when we used concentrated solutions.”

The KAUST team partnered with Oxford theoreticians to identify how interfaces influence perovskite growth in ITC. They propose that metal halides and solvent molecules initially cling together in tight complexes that begin to stretch and weaken at higher temperatures. With sufficient thermal energy, the complex breaks and perovskites begin to crystallize.

But interestingly, the researchers found that complexes located at the solution surface can experience additional forces due to surface tension—the strong cohesive forces that enable certain insects to stride over lakes and ponds. The extra pull provided by the surface makes it much easier to separate the solvent-perovskite complexes and nucleate crystals that float on top of the liquid.

Exploiting this knowledge helped the team produce centimeter-sized, ultrathin single crystals and prototype a photodetector with characteristics comparable to state-of-the-art devices. Although the single crystals are currently fragile and difficult to handle due to their microscale thicknesses, Zhumekenov explains that this method could help direct the perovskite growth onto specific substrates.

“Taking into account the roles of interfaces and surface tension could have a fundamental impact,” he says, “we can get large-area growth, and it’s not limited to specific metal cations—you could have a library of materials with perovskite structures.”

Source: King Abdullah University of Science and Technology