Long-lasting flow battery could run for more than a decade with minimum upkeep – Harvard Paulson School of Engineering 


Battery stores energy in nontoxic, noncorrosive aqueous solutions

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new flow battery that stores energy in organic molecules dissolved in neutral pH water.

This new chemistry allows for a non-toxic, non-corrosive battery with an exceptionally long lifetime and offers the potential to significantly decrease the costs of production.

The research, published in ACS Energy Letters, was led by Michael Aziz, the Gene and Tracy Sykes Professor of Materials and Energy Technologies and Roy Gordon, the Thomas Dudley Cabot Professor of Chemistry and Professor of Materials Science.

Flow batteries store energy in liquid solutions in external tanks — the bigger the tanks, the more energy they store.


Flow batteries are a promising storage solution for renewable, intermittent energy like wind and solar but today’s flow batteries often suffer degraded energy storage capacity after many charge-discharge cycles, requiring periodic maintenance of the electrolyte to restore the capacity.




By modifying the structures of molecules used in the positive and negative electrolyte solutions, and making them water soluble, the Harvard team was able to engineer a battery that loses only one percent of its capacity per 1000 cycles.


“Lithium ion batteries don’t even survive 1000 complete charge/discharge cycles,” said Aziz.

“Because we were able to dissolve the electrolytes in neutral water, this is a long-lasting battery that you could put in your basement,” said Gordon.

 

 

“If it spilled on the floor, it wouldn’t eat the concrete and since the medium is noncorrosive, you can use cheaper materials to build the components of the batteries, like the tanks and pumps.”

This reduction of cost is important. The Department of Energy (DOE) has set a goal of building a battery that can store energy for less than $100 per kilowatt-hour, which would make stored wind and solar energy competitive with energy produced from traditional power plants.


“If you can get anywhere near this cost target then you change the world,” said Aziz. “It becomes cost effective to put batteries in so many places. This research puts us one step closer to reaching that target.”

“If you can get anywhere near this cost target then you change the world,” said Aziz. “It becomes cost effective to put batteries in so many places. This research puts us one step closer to reaching that target.”

“This work on aqueous soluble organic electrolytes is of high significance in pointing the way towards future batteries with vastly improved cycle life and considerably lower cost,” said Imre Gyuk, Director of Energy Storage Research at the Office of Electricity of the DOE.

“I expect that efficient, long duration flow batteries will become standard as part of the infrastructure of the electric grid.”

The key to designing the battery was to first figure out why previous molecules were degrading so quickly in neutral solutions, said Eugene Beh, a postdoctoral fellow and first author of the paper.

By first identifying how the molecule viologen in the negative electrolyte was decomposing, Beh was able to modify its molecular structure to make it more resilient.

Next, the team turned to ferrocene, a molecule well known for its electrochemical properties, for the positive electrolyte.

“Ferrocene is great for storing charge but is completely insoluble in water,” said Beh. “It has been used in other batteries with organic solvents, which are flammable and expensive.”

But by functionalizing ferrocene molecules the same way as the viologen, the team was able to turn an insoluble molecule into a highly soluble one that could be cycled stably.

“Aqueous soluble ferrocenes represent a whole new class of molecules for flow batteries,” said Aziz.

The neutral pH should be especially helpful in lowering the cost of the ion-selective membrane that separates the two sides of the battery.

Most flow batteries today use expensive polymers that can withstand the aggressive chemistry inside the battery. They can account for up to one-third of the total cost of the device. 


With essentially salt water on both sides of the membrane, expensive polymers can be replaced by cheap hydrocarbons. 

This research was coauthored by Diana De Porcellinis, Rebecca Gracia, and Kay Xia. It was supported by the Office of Electricity Delivery and Energy Reliability of the DOE and by the DOE’s Advanced Research Projects Agency-Energy.

With assistance from Harvard’s Office of Technology Development (OTD), the researchers are working with several companies to scale up the technology for industrial applications and to optimize the interactions between the membrane and the electrolyte.

Harvard OTD has filed a portfolio of pending patents on innovations in flow battery technology.

New battery technology that could run for more than a decade could revolutionize renewable energy – Harvard University


Harvard Battery Research aziz_650

The race is on to build the next-generation battery that could help the world switch over to clean energy. But as Bill Gates explained in his blog last year: “storing energy turns out to be surprisingly hard and expensive”.

 

Now Harvard researchers have developed a cheap, non-toxic battery that lasts more than 10 years, which they say could be a game changer for renewable energy storage.

Solar installers from Baker Electric place solar panels on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016.  Picture taken October 14, 2016.      REUTERS/Mike Blake - RTX2QGWW

Image: REUTERS/Mike Blake

The researchers from the John A. Paulson School of Engineering and Applied Sciences published a paper in the journal ACS Energy Letters saying that they have developed a breakthrough technology.

 

Their new type of battery stores energy in organic molecules dissolved in neutral pH water. This makes the battery non-toxic and cheaper. It’s suitable for home storage and lasts for more than a decade. “This is a long-lasting battery you could put in your basement,” Roy Gordon, a lead researcher and the Thomas Dudley Cabot Professor of Chemistry and Professor of Materials Science, said in a Harvard news article.

“If it spilled on the floor, it wouldn’t eat the concrete and since the medium is non-corrosive, you can use cheaper materials to build the components of the batteries, like the tanks and pumps.”

 

The energy storage problem

There’s a big problem with renewable energy sources: Intermittency. In other words, how to keep the lights on when the sun isn’t shining or the wind isn’t blowing.

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 Image: International Energy Agency

In recent years, universities and the tech sector have been working on better batteries that they hope could help solve the energy storage problem. Despite significant improvements though, batteries are riddled with issues such as high cost, toxicity and short lifespan.

 

Solar power customers usually have two options to store power: lithium-ion batteries such as the ones found in electronics, which are still very expensive; or lead-acid batteries. These cost half as much, but need a lot of maintenance and contain toxic materials.

 Image 3

Image: Bloomberg New Energy Finance

In one emerging and promising technology is the “v-flow” battery, which uses vanadium in large external tanks of corrosive acids. 

The bigger the tanks, the more energy they store. But there’s a catch: vanadium is an expensive metal and like all other battery technologies, v-flow batteries lose capacity after a few years.

The quest for the next-generation battery

The US Department of Energy has set a goal of building a battery that can store energy for less than $100 per kilowatt-hour, which would make stored wind and solar energy competitive with energy produced from traditional power plants.

 

The Harvard researchers say their breakthrough puts them within sight of this goal.

“If you can get anywhere near this cost target then you change the world,” said Michael Aziz, lead researcher and professor of Materials and Energy Technologies at Harvard. “It becomes cost effective to put batteries in so many places. This research puts us one step closer to reaching that target.”

 

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Video: Next Generation Silicon-Nanowire Batteries

 

A new company has been formed to exploit and commercialize the Next Generation Super-Capacitors and Batteries. The opportunity is based on Technology & Exclusive IP Licensing Rights from Rice University, discovered/ curated by Dr. James M. Tour, named “One of the Fifty (50) most influential scientists in the World today”

The Porous Silicon Nanowires & Lithium Cobalt Oxide technology has been advanced to provide a New Generation Battery that is:

 Energy Dense
 High Specific Power
 Affordable Cost
 Low Manufacturing Cost
 Rapid Charge/ Re-Charge
 Flexible Form Factor
 Long Warranty Life
 Non-Toxic
 Highly Scalable

Key Markets & Commercial Applications

 Motor Cycle/ EV Batteries
 Marine and Drone Batteries
 Medical Devices and
 Power Banks
 Estimated $112 Billion Market for Rechargeable Batteries by 2025

 

 

Battery-free implantable medical device powered by human body – A biological supercapacitor


battery-free-medical-implants-1

 

Researchers from UCLA and the University of Connecticut have designed a new biofriendly energy storage system called a biological supercapacitor, which operates using charged particles, or ions, from fluids in the human body. The device is harmless to the body’s biological systems, and it could lead to longer-lasting cardiac pacemakers and other implantable medical devices.   The UCLA team was led by Richard Kaner, a distinguished professor of chemistry and biochemistry, and of materials science and engineering, and the Connecticut researchers were led by James Rusling, a professor of chemistry and cell biology.

A paper about their design was published this week in the journal Advanced Energy Materials.   Pacemakers — which help regulate abnormal heart rhythms — and other implantable devices have saved countless lives. But they’re powered by traditional batteries that eventually run out of power and must be replaced, meaning another painful surgery and the accompanying risk of infection. In addition, batteries contain toxic materials that could endanger the patient if they leak.

The researchers propose storing energy in those devices without a battery. The supercapacitor they invented charges using electrolytes from biological fluids like blood serum and urine, and it would work with another device called an energy harvester, which converts heat and motion from the human body into electricity — in much the same way that self-winding watches are powered by the wearer’s body movements. That electricity is then captured by the supercapacitor.   “Combining energy harvesters with supercapacitors can provide endless power for lifelong implantable devices that may never need to be replaced,” said Maher El-Kady, a UCLA postdoctoral researcher and a co-author of the study.

Modern pacemakers are typically about 6 to 8 millimeters thick, and about the same diameter as a 50-cent coin; about half of that space is usually occupied by the battery. The new supercapacitor is only 1 micrometer thick — much smaller than the thickness of a human hair — meaning that it could improve implantable devices’ energy efficiency. It also can maintain its performance for a long time, bend and twist inside the body without any mechanical damage, and store more charge than the energy lithium film batteries of comparable size that are currently used in pacemakers.   “Unlike batteries that use chemical reactions that involve toxic chemicals and electrolytes to store energy, this new class of biosupercapacitors stores energy by utilizing readily available ions, or charged molecules, from the blood serum,” said Islam Mosa, a Connecticut graduate student and first author of the study.

The new biosupercapacitor comprises a carbon nanomaterial called graphene layered with modified human proteins as an electrode, a conductor through which electricity from the energy harvester can enter or leave. The new platform could eventually also be used to develop next-generation implantable devices to speed up bone growth, promote healing or stimulate the brain, Kaner said.

Although supercapacitors have not yet been widely used in medical devices, the study shows that they may be viable for that purpose.   “In order to be effective, battery-free pacemakers must have supercapacitors that can capture, store and transport energy, and commercial supercapacitors are too slow to make it work,” El-Kady said. “Our research focused on custom-designing our supercapacitor to capture energy effectively, and finding a way to make it compatible with the human body.”   Among the paper’s other authors are the University of Connecticut’s Challa Kumar, Ashis Basu and Karteek Kadimisetty. The research was supported by the National Institute of Health’s National Institute of Biomedical Imaging and Bioengineering, the NIH’s National Institute of Environmental Health Sciences, and a National Science Foundation EAGER grant.   Source and top image: UCLA Engineering

 

An EV Battery That Charges Fully In 5 Minutes? Commercialization Step-Up Could Come Soon


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Electric vehicles now comprise a substantial part of the automotive market. But the fact remains that despite the increasing number of charging stations, it is still inconvenient to charge a car in comparison to getting a tank full of gas.

StoreDot, an Israeli startup, might have the solution to the woes of electric vehicle (EV) owners, with a new battery it claims can fully charge in five minutes and drive the EV 300 miles on a single charge.

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Read About the Company: Enabling the Future of Charging

The battery is made of nano-materials in a layered structure, made of special organic compounds manufactured by the company. This, the company said, is a massive improvement over traditional lithium-ion battery.

The company first demonstrated the technology at Microsoft Think Next in 2015. The company says the batteries are in the “advanced stages of development” and might be integrated into electric vehicles in the next three years. It also says that its chemical compound is not flammable and has a higher level of combustion, reducing the level of resistance in the batteries making it safe for use in cars.

The batteries won’t be too difficult to manufacture either — the company estimates that 80 percent of the manufacturing process is the same as regular lithium-ion batteries.

StoreDot specializes in battery technology. Last year, it showcased a smartphone battery capable of fully charging within 30 seconds. The EV battery is a scaled up version of this battery which has multi-function electrodes, a combination of polymer and metal oxide.

Watch the Video

 

Read More

 

An electric car battery that could charge in just five minutes ~ Where is the Israeli Start-Up “+StoreDot” One Year Later? +Video

storedot-ev-battery-21-889x592 (1)

Energy from the sun, stored in a liquid – and released on demand OR … Solar to Hydrogen Fuel … And the Winner Is?


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“The solar energy business has been trying to overcome … challenge for years. The cost of installing solar panels has fallen dramatically but storing the energy produced for later use has been problematic.”

Solar Crash I solar-and-wind-energy“In a single hour, the amount of power from the sun that strikes the Earth is more than the entire world consumes in an year.” To put that in numbers, from the US Department of Energy 

 

 

Each hour 430 quintillion Joules of energy from the sun hits the Earth. That’s 430 with 18 zeroes after it! In comparison, the total amount of energy that all humans use in a year is 410 quintillion JoulesFor context, the average American home used 39 billion Joules of electricity in 2013.

HOME SOLAR-master675Read About: What are the Most Efficient Solar Panels on the Market?

 

Clearly, we have in our sun “a source of unlimited renewable energy”. But how can we best harness this resource? How can we convert and  “store” this energy resource on for sun-less days or at night time … when we also have energy needs?

Now therein lies the challenge!

Would you buy a smartphone that only worked when the sun was shining? Probably not. What it if was only half the cost of your current model: surely an upgrade would be tempting? No, thought not.

The solar energy business has been trying to overcome a similar challenge for years. The cost of installing solar panels has fallen dramatically but storing the energy produced for later use has been problematic.

 

Now scientists in Sweden have found a new way to store solar energy in chemical liquids. Although still in an early phase, with niche applications, the discovery has the potential to make solar power more practical and widespread.

Until now, solar energy storage has relied on batteries, which have improved in recent years. However, they are still bulky and expensive, and they degrade over time.

Image: Energy and Environmental Science

Trap and release solar power on demand

A research team from Chalmers University of Technology in Gothenburg made a prototype hybrid device with two parts. It’s made from silica and quartz with tiny fluid channels cut into both sections.

 

The top part is filled with a liquid that stores solar energy in the chemical bonds of a molecule. This method of storing solar energy remains stable for several months. The energy can be released as heat whenever it is required.

The lower section of the device uses sunlight to heat water which can be used immediately. This combination of storage and water heating means that over 80% of incoming sunlight is converted into usable energy.

Suddenly, solar power looks a lot more practical. Compared to traditional battery storage, the new system is more compact and should prove relatively inexpensive, according to the researchers. The technology is in the early stages of development and may not be ready for domestic and business use for some time.

 

From the lab to off-grid power stations or satellites?

The researchers wrote in the journal Energy & Environmental Science: “This energy can be transported, and delivered in very precise amounts with high reliability(…) As is the case with any new technology, initial applications will be in niches where [molecular storage] offers unique technical properties and where cost-per-joule is of lesser importance.”

A view of solar panels, set up on what will be the biggest integrated solar panel roof of the world, in a farm in Weinbourg, Eastern France February 12, 2009. Bright winter sun dissolves a blanket of snow on barn roofs to reveal a bold new sideline for farmer Jean-Luc Westphal: besides producing eggs and grains, he is to generate solar power for thousands of homes. Picture taken February 12.         To match feature FRANCE-FARMER/SOLAR              REUTERS/Vincent Kessler  (FRANCE) - RTXC0A6     Image: REUTERS: Kessler

The team now plans to test the real-world performance of the technology and estimate how much it will cost. Initially, the device could be used in off-grid power stations, extreme environments, and satellite thermal control systems.

 

Editor’s Note: As Solomon wrote in  Ecclesiastes 1:9:What has been will be again, what has been done will be done again; there is nothing new under the sun.”

Storing Solar Energy chemically and converting ‘waste heat’ has and is the subject of many research and implementation Projects around the globe. Will this method prove to be “the one?” This writer (IMHO) sees limited application, but not a broadly accepted and integrated solution.

Solar Energy to Hydrogen Fuel

So where does that leave us? We have been following the efforts of a number of Researchers/ Universities who are exploring and developing “Sunlight to Hydrogen Fuel” technologies to harness the enormous and almost inexhaustible energy source power-house … our sun! What do you think? Please leave us your Comments and we will share the results with our readers!

Read More

We have written and posted extensively about ‘Solar to Hydrogen Renewable Energy’ – here are some of our previous Posts:

Sunlight to hydrogen fuel 10-scientistsusScientists using sunlight, water to produce renewable hydrogen power

 

 

Rice logo_rice3Solar-Powered Hydrogen Fuel Cells

Researchers at Rice University are on to a relatively simple, low-cost way to pry hydrogen loose from water, using the sun as an energy source. The new system involves channeling high-energy “hot” electrons into a useful purpose before they get a chance to cool down. If the research progresses, that’s great news for the hydrogen […]

HyperSolar 16002743_1389245094451149_1664722947660779785_nHyperSolar reaches new milestone in commercial hydrogen fuel production

HyperSolar has achieved a major milestone with its hybrid technology HyperSolar, a company that specializes in combining hydrogen fuel cells with solar energy, has reached a significant milestone in terms of hydrogen production. The company harnesses the power of the sun in order to generate the electrical power needed to produce hydrogen fuel. This is […]

riceresearch-solar-water-split-090415 (1)Rice University Research Team Demonstrates Solar Water-Splitting Technology: Renewable Solar Energy + Clean – Low Cost Hydrogen Fuel

Rice University researchers have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules. The technology, which is described online in the American Chemical Society journal Nano Letters, relies on a configuration of light-activated gold nanoparticles that harvest sunlight and transfer solar energy […]

NREL I downloadNREL Establishes World Record for Solar Hydrogen Production

NREL researchers Myles Steiner (left), John Turner, Todd Deutsch and James Young stand in front of an atmospheric pressure MDCVD reactor used to grow crystalline semiconductor structures. They are co-authors of the paper “Direct Solar-to-Hydrogen Conversion via Inverted Metamorphic Multijunction Semiconductor Architectures” published in Nature Energy. Photo by Dennis Schroeder.   Scientists at the U.S. […]

NREL CSM Solar Hydro img_0095NREL & Colorado School of Mines Researchers Capture Excess Photon Energy to Produce Solar Fuels

Photo shows a lead sulfide quantum dot solar cell. A lead sulfide quantum dot solar cell developed by researchers at NREL. Photo by Dennis Schroeder.

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have developed a proof-of-principle photo-electro-chemical cell capable of capturing excess photon energy normally lost to generating heat. Using quantum […]

Chemically tailored graphene advances Potential for use in Semiconductors


Graphene chemicallytaSection of a graphene network with chemically bound hydrogen atom: the spectral vibrational signature of the single carbon-carbon bonds adjacent to the bound hydrogen atom is highlighted in different colors. Credit: Frank Hauke, FAU

Graphene is considered as one of the most promising new materials. However, the systematic insertion of chemically bound atoms and molecules to control its properties is still a major challenge. Now, for the first time, scientists of the Friedrich-Alexander-Universität Erlangen-Nürnberg, the University of Vienna, the Freie Universität Berlin and the University Yachay Tech in Ecuador succeeded in precisely verifying the spectral fingerprint of such compounds in both theory and experiment. Their results are published in the scientific journal Nature Communications.

Two-dimensional consists of single layers of carbon atoms and exhibits intriguing properties. The transparent material conducts electricity and heat extremely well. It is at the same time flexible and solid. Additionally, the electrical conductivity can be continuously varied between a metal and a semiconductor by, e.g., inserting chemically bound atoms and molecules into the graphene structure – the so-called functional groups. These unique properties offer a wide range of future applications as e.g. for new developments in optoelectronics or ultrafast components in the semiconductor industry. However, a successful use of graphene in the semiconductor industry can only be achieved if properties such as the conductivity, the size and the defects of the graphene structure induced by the functional groups can already be modulated during the synthesis of graphene.

In an international collaboration scientists led by Andreas Hirsch from the Friedrich-Alexander-Universität Erlangen-Nürnberg in close cooperation with Thomas Pichler from the University of Vienna accomplished a crucial breakthrough: using the latter’s newly developed experimental set-up they were able to identify, for the first time, vibrational spectra as the specific fingerprints of step-by-step chemically modified graphene by means of light scattering. This spectral signature, which was also theoretically attested, allows to determine the type and the number of in a fast and precise way. Among the reactions they examined, was the chemical binding of hydrogen to graphene. This was implemented by a controlled chemical reaction between water and particular compounds in which ions are inserted in graphite, a crystalline form of carbon.

Additional benefits

“This method of the in-situ Raman spectroscopy is a highly effective technique which allows controlling the function of graphene in a fast, contact-free and extensive way already during the production of the material,” says J. Chacon from Yachay Tech, one of the two lead authors of the study. This enables the production of tailored graphene-based materials with controlled electronic transport properties and their utilisation in .

Explore further: Low-cost and defect-free graphene

More information: Philipp Vecera et al. Precise determination of graphene functionalization by in situ Raman spectroscopy, Nature Communications (2017). DOI: 10.1038/ncomms15192

 

50 nm thick ‘Nanosheet Semiconductors’ – Ideal as biosensors, flexible electronics, displays and solar cells


Decal semiconductoA 50nm pentacene film spanned across a 2 mm hole. Credit: Simon Noever, LMU

No more error-prone evaporation deposition, drop casting or printing: Scientists at LMU Munich and FSU Jena have developed organic semiconductor nanosheets, which can easily be removed from a growth substrate and placed on other substrates.

Today’s computer processors are composed of billions of transistors. These electronic components normally consist of material, insulator, , and electrode. A dream of many scientists is to have each of these elements available as transferable sheets, which would allow them to design new electronic devices simply by stacking.

This has now become a reality for the organic semiconductor material pentacene: Dr. Bert Nickel, a physicist at LMU Munich, and Professor Andrey Turchanin (Friedrich Schiller University Jena), together with their teams, have, for the first time, managed to create mechanically stable pentacene nanosheets.

The researchers describe their method in the journal Advanced Materials. They first cover a small silicon wafer with a thin layer of a water-soluble organic film and deposit pentacene molecules upon it until a layer roughly 50 nanometers thick has formed. The next step is crucial: by irradiation with low-energy electrons, the topmost three to four levels of pentacene molecular layers are crosslinked, forming a “skin” that is only about five nanometers thick. This crosslinked layer stabilizes the entire pentacene film so well that it can be removed as a sheet from a silicon wafer in water and transferred to another surface using ordinary tweezers.

Apart from the ability to transfer them, the new semiconductor nanosheets have other advantages. The new method does not require any potentially interfering solvents, for example. In addition, after deposition, the nanosheet sticks firmly to the electrical contacts by van der Waals forces, resulting in a low contact resistance of the final electronic devices. Last but not least, organic semiconductor nanosheets can now be deposited onto significantly more technologically relevant substrates than hitherto.

Of particular interest is the extremely high mechanical stability of the newly developed pentacene nanosheets, which enables them to be applied as free-standing nanomembranes to perforated substrates with dimensions of tens of micrometers. That is equivalent to spanning a 25-meter pool with plastic wrap. “These virtually freely suspended semiconductors have great potential,” explains Nickel. “They can be accessed from two sides and could be connected through an electrolyte, which would make them ideal as biosensors, for example”. “Another promising application is their implementation in flexible electronics for manufacturing of devices for vital data acquisition or production of displays and solar cells,” Turchanin says.

Explore further: Nano-imaging probes molecular disorder

More information: Simon J. Noever et al. Transferable Organic Semiconductor Nanosheets for Application in Electronic Devices, Advanced Materials (2017). DOI: 10.1002/adma.201606283

 

Dendrite-free lithium metal anodes using Nitrogen-doped graphene matrix – Solves Safety & Power Challenges


Dendrite Free LI Anodes 590c50b37b0b0

 

 

Recently, Researchers in Tsinghua University have proposed a nitrogen-doped graphene matrix with densely and uniformly distributed lithiophilic functional groups for dendrite-free lithium metal anodes, appearing in the journal Angewandte Chemie International Edition.

Since lithium metal possesses an ultrahigh theoretical specific capacity (3860 mAh g-1) and the lowest negative electrochemical potential (-3.040 V vs. the standard hydrogen electrode), lithium metal has been regarded as the most promising electrode material for next-generation high-energy-density batteries. However, the application of lithium metal batteries is still not in sight. “Lithium dendrite growth has hindered the development of lithium metal anodes,” said Dr. Qiang Zhang, the corresponding author, a faculty at Department of Chemical Engineering, Tsinghua University. “Lithium dendrites that form during repeated lithium plating and stripping cycles can not only induce many ‘dead Li’ with irreversible capacity loss, but also cause internal short circuits in batteries and other hazardous issues.”

LI Dendrite separator“We found that a lithiophilic material with good metallic lithium affinity can guide the lithium metal nucleation. Therefore, designing a lithium-plating with a high surface area and lithiophilic surface makes sense for a safe and efficient ,” said Xiao-Ru Chen, an undergraduate student in Tsinghua University. “So we employed a nitrogen-doped graphene matrix with densely and uniformly distributed nitrogen containing to guide lithium metal nucleation and growth.”

“The nitrogen containing functional groups are lithiophilic sites, confirmed by our experimental and DFT calculation results. Lithium metal can plate with uniform nucleation during the charging process, followed by growth into dendrite-free morphology. While on the normal Cu foil-based anode, the nucleation sites are scattered, which may cause lithium dendrite growth more easily,” said Xiang Chen, a Ph.D. student at Tsinghua University.

With the lithiophilic nitrogen-containing functional groups, the N-doped graphene matrix can regulate the nucleation process of lithium electrodeposition. As a result, dendrite-free lithium metal deposits were obtained. Additionally, this matrix shows impressive electrochemical performance. The Coulombic efficiency of the N-doped graphene-based electrode at a current density of 1.0 mA cm-2 and a cycle capacity of 1.0 mAh cm-2 can reach 98 percent for nearly 200 cycles.

“We have proposed a new strategy based on lithiophilic site-guided nucleation to settle the tough dendrite challenge in this publication,” said Qiang. “Further research is required to investigate and control the lithium nucleation in lithium metal batteries. We believe that the practical application of lithium anodes can be finally realized.” The control of the process of plating with a lithiophilic matrix has shed a new light on all -based batteries, such as Li-S, Li-O2 and future Li-ion batteries.

Explore further: New battery coating could improve smart phones and electric vehicles

More information: Rui Zhang et al. Lithiophilic Sites in Doped Graphene Guide Uniform Lithium Nucleation for Dendrite-Free Lithium Metal Anodes, Angewandte Chemie International Edition (2017). DOI: 10.1002/anie.201702099

 

U of Minnesota: Discovery of new transparent thin film material – Less Costly than Indium – Could lead to smaller, faster, more powerful electronics, improve solar cells


U of Minn ThinFilm Solar 5-discoveryofnA team of researchers, led by the University of Minnesota, have discovered a new nano-scale thin film material with the highest-ever conductivity in its class.  Credit: University of Minnesota

A team of researchers, led by the University of Minnesota, have discovered a new nano-scale thin film material with the highest-ever conductivity in its class. The new material could lead to smaller, faster, and more powerful electronics, as well as more efficient solar cells.

The discovery is being published today in Nature Communications, an open access journal that publishes high-quality research from all areas of the natural sciences.

Researchers say that what makes this new material so unique is that it has a high conductivity, which helps electronics conduct more electricity and become more powerful. But the material also has a wide bandgap, which means light can easily pass through the material making it optically transparent. In most cases, materials with wide bandgap, usually have either low conductivity or poor transparency.

“The high conductivity and wide bandgap make this an ideal material for making optically transparent conducting films which could be used in a wide variety of electronic devices, including , electronic displays, touchscreens and even in which light needs to pass through the device,” said Bharat Jalan, a University of Minnesota chemical engineering and materials science professor and the lead researcher on the study.

Currently, most of the in our electronics use a chemical element called indium. The price of indium has gone up tremendously in the past few years significantly adding to the cost of current display technology. As a result, there has been tremendous effort to find alternative materials that work as well, or even better, than indium-based transparent conductors.

In this study, researchers found a solution. They developed a new transparent conducting thin film using a novel synthesis method, in which they grew a BaSnO3 thin film (a combination of barium, tin and oxygen, called barium stannate), but replaced elemental tin source with a chemical precursor of tin. The chemical precursor of tin has unique, radical properties that enhanced the chemical reactivity and greatly improved the metal oxide formation process. Both barium and tin are significantly cheaper than indium and are abundantly available.

“We were quite surprised at how well this unconventional approach worked the very first time we used the tin chemical precursor,” said University of Minnesota engineering and materials science graduate student Abhinav Prakash, the first author of the paper. “It was a big risk, but it was quite a big breakthrough for us.”

Jalan and Prakash said this new process allowed them to create this material with unprecedented control over thickness, composition, and defect concentration and that this process should be highly suitable for a number of other material systems where the element is hard to oxidize. The new process is also reproducible and scalable.

They further added that it was the structurally superior quality with improved defect concentration that allowed them to discover high conductivity in the material. They said the next step is to continue to reduce the defects at the atomic scale.

“Even though this material has the highest within the same class, there is much room for improvement in addition, to the outstanding potential for discovering new physics if we decrease the defects. That’s our next goal,” Jalan said.

Explore further: See-through circuitry: New and cheap alternative for transparent electronics

More information: Abhinav Prakash et al, Wide bandgap BaSnO3 films with room temperature conductivity exceeding 104 S cm−1, Nature Communications (2017). DOI: 10.1038/ncomms15167

 

Los Alamos National Laboratory Studies Perovskites for Efficient Optoelectronics: Video


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In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are gaining an extra degree of freedom in designing and fabricating efficient optoelectronic devices based on 2D layered hybrid perovskites. Industrial applications could include low cost solar cells, LEDs, laser diodes, detectors, and other nano-optoelectronic devices.

Los Alamos Lab lanl-logo-footerThe 2D, near-single-crystalline “Ruddlesden-Popper” thin films have an out-of-plane orientation so that uninhibited charge transport occurs through the perovskite layers in planar devices. The new research finds the existence of “layer-edge-states” at the edges of the perovskite layers which are key to both high efficiency of solar cells (greater than 12 percent) and high fluorescence efficiency (a few tens of percent) for LEDs. The spontaneous conversion of excitons (bound electron-hole pairs) to free carriers via these layer-edge states appears to be the key to the improvement of the photovoltaic and light-emitting thin film layered materials.

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See the news release here:
http://www.lanl.gov/discover/news-rel…

And the research paper in Science:
http://science.sciencemag.org/content…