Chinese scientists have transformed rusty stainless steel mesh into electrodes with outstanding electrochemical properties for potassium-ion batteries. The scientists have made good use of a waste while finding an innovative solution to a technical problem.

Image Credit: Changchun Institute of Applied Chemistry, Chinese Academy of Sciences. Click image for the largest view.

The research team reported their findings in the journal Angewandte Chemie. They describe that the rust is converted directly into a compact layer with a grid structure that can store potassium ions. A coating of reduced graphite oxide increases the conductivity and stability during charge/discharge cycles.

Xin-Bo Zhang explains that increasing use of renewable energy requires effective energy storage within the grid. Lithium ion batteries, widely used in portable electronics, are promising candidates. Lithium ion batteries are based on the displacement of lithium ions. While charging, the ions move toward the graphite electrode, where they are stored between the layers of carbon. When discharging, they are released. However, lithium is expensive and reserves are limited. Sodium ion batteries have been explored as an alternative.

“Potassium ions are just as inexpensive and readily available as sodium, and potassium ion batteries would be superior from the electric aspect. However, the significantly larger radius of the potassium ions has posed a problem. Repeated storage and release of these ions destabilizes the materials currently used in electrodes,” said Xin-Bo Zhang.

Zhang and a team from the Chinese Academy of sciences and Jilin University (Changchun, China) have now found an elegant solution in their use of a waste material to make novel electrodes: rejected stainless steel mesh from filters and sieves. Despite the excellent durability of these grids, harsh conditions does lead to some corrosion. The metal can be reclaimed in a furnace, but this process requires a great deal of money, time, and energy, as well as producing emissions.

Zhang pointed out, “Conversion into electrodes could develop into a more ecologically and economically sensible form of recycling.”

The corroded mesh is dipped into a solution of potassium ferrocyanide (yellow prussiate of potash, known as a fining agent for wine). This dissolves iron, chromium, and nickel ions out of the rust layer. These combine with ferricyanide ions into the complex salt known as Prussian blue, a dark blue pigment that is deposited onto the surface of the mesh as scaffold-like nanocubes. Potassium ions can easily and rapidly be stored in and released from these structures.

The researchers then use a dip-coating process to deposit a layer of graphene oxide (oxidized graphite layers). This layer nestles tightly onto the nanocubes. Subsequent reduction converts the graphene oxide to reduced graphene oxide (RGO), which consists of layers of graphite with isolated oxygen atoms.

Zhang explained, “The RGO coating inhibits clumping and detachment of the active material. At the same time, it significantly increases the conductivity and opens ultrafast electron-transport pathways.”

In tests, coin cells made with these new electrodes demonstrate excellent capacity, discharge voltages, rate capability, and outstanding cycle stability. Because the inexpensive, binder-free electrodes are very flexible, they are highly suitable for use in flexible electronic devices.

The potassium battery will likely find a place in the market. This breakout for electrodes bodes well. While the press release isn’t specific, one can assume the cycle life and capacity estimates are pretty good.

The hunt is on in earnest now for alternatives to alkaline, lead acid and lithium chemistries. One wonders sometimes what ever happened to progress for nickel and cadmium batteries? Lots of battery chemistries and competition is going to be great for consumers.

Argonne National Laboratory researchers have identified a nickel oxide compound as an unconventional but promising candidate material for high-temperature superconductivity. The project combined crystal growth, X-ray spectroscopy and computational theory.

The team successfully synthesized single crystals of a metallic trilayer nickelate compound, a feat the researchers believe to be a first.

Materials scientists at Argonne National Laboratory synthesized these single crystals of a metallic trilayer nickelate compound via a high-pressure crystal growth process. Image Credit: Argonne National Laboratory. Click image for the largest view.

John Mitchell, an Argonne Distinguished Fellow and associate director of the laboratory’s Materials Science Division, who led the project, which combined crystal growth, X-ray spectroscopy, and computational theory said, “It’s poised for superconductivity in a way not found in other nickel oxides. We’re very hopeful that all we have to do now is find the right electron concentration.”

This nickel oxide compound does not superconduct, but, he added, “It’s poised for superconductivity in a way not found in other nickel oxides. We’re very hopeful that all we have to do now is find the right electron concentration.”

Mitchell and seven co-authors announced their results in Nature Physics.

Superconducting materials are technologically important because electricity flows through them without resistance. High-temperature superconductors could lead to faster, more efficient electronic devices, grids that can transmit power without energy loss and ultra-fast levitating trains that ride frictionless magnets instead of rails among the leading ideas.

Only low-temperature superconductivity seemed possible before 1986, but materials that superconduct at low temperatures are impractical because they must first be cooled to hundreds of degrees below zero. In 1986, however, discovery of high-temperature superconductivity in copper oxide compounds called cuprates engendered new technological potential for the phenomenon.

But after three decades of ensuing research, exactly how cuprate superconductivity works remains a defining problem in the field. One approach to solving this problem has been to study compounds that have similar crystal, magnetic and electronic structures to the cuprates.

Nickel-based oxides – nickelates – have long been considered as potential cuprate analogs because the element sits immediately adjacent to copper in the periodic table. Thus far, Mitchell noted, “That’s been an unsuccessful quest.” As he and his co-authors noted in their Nature Physics paper, “None of these analogs have been superconducting, and few are even metallic.”

The nickelate that the Argonne team has created is a quasi-two-dimensional trilayer compound, meaning that it consists of three layers of nickel oxide that are separated by spacer layers of praseodymium oxide.

“Thus it looks more two-dimensional than three-dimensional, structurally and electronically,” Mitchell said.

This nickelate and a compound containing lanthanum rather than praseodymium both share the quasi-two-dimensional trilayer structure. But the lanthanum analog is non-metallic and adopts a so-called “charge-stripe” phase, an electronic property that makes the material an insulator, the opposite of a superconductor.

“For some yet-unknown reason, the praseodymium system does not form these stripes,” Mitchell said. “It remains metallic and so is certainly the more likely candidate for superconductivity.”

Argonne is one of a few laboratories in the world where the compound could be created. The Materials Science Division’s high-pressure optical-image floating zone furnace has special capabilities. It can attain pressures of 150 atmospheres (equivalent to the crushing pressures found at oceanic depths of nearly 5,000 feet) and temperatures of approximately 2,000 degrees Celsius (more than 3,600 degrees Fahrenheit), conditions needed to grow the crystals.

“We didn’t know for sure we could make these materials,” said Argonne postdoctoral researcher Junjie Zhang, the first author on the study. But indeed, they managed to grow the crystals measuring a few millimeters in diameter.

The research team verified that the electronic structure of the nickelate resembles that of cuprate materials by taking X-ray absorption spectroscopy measurements at the Advanced Photon Source, a DOE Office of Science User Facility, and by performing density functional theory calculations. Materials scientists use density functional theory to investigate the electronic properties of condensed matter systems.

“I’ve spent my entire career not making high-temperature superconductors,” Mitchell joked. But that could change in the next phase of his team’s research: attempting to induce superconductivity in their nickelate material using a chemical process called electron doping, in which impurities are deliberately added to a material to influence its properties.

The researchers are zeroing in. Hopefully they find a bonanza of opportunities for superconductivity material choices. Its going to take more time, but the payoff will be huge and last forever.

University of Houston (UH) researchers have discovered a new material that has proven an effective anode for acid and alkaline batteries, including emerging aqueous metal-ion batteries. Importantly, the material offers the promise of safe, long-lasting batteries that work across a range of temperatures and is quite low cost.

Quinones is a new material that has proven an effective anode for acid and alkaline batteries, including emerging aqueous metal-ion batteries, offering the promise of safe, long-lasting batteries that work across a range of temperatures. Image Credit: University of Houston. Click image for the largest view.

Modern batteries power everything from cars to cell phones, but they are far from perfect, among the issues – they catch fire, they perform poorly in cold weather and they have relatively short lifecycles. The UH researchers have described a new class of material that addresses many of those concerns in a new article published in Nature Materials.

The researchers, led by Yan Yao, associate professor of electrical and computer engineering, report their use of quinones – an inexpensive, earth-abundant and easily recyclable material – to create stable anode composites for any aqueous rechargeable battery.

Yao, who is also a principal investigator with the Texas Center for Superconductivity at UH, with an appointment to the chemical and biomolecular engineering faculty said, “This new material is cheap and chemically stable in such a corrosive environment.” The material also can be used to create a “drop-in replacement” for current battery anodes, allowing the new material to be used without changing existing battery manufacturing lines.

“This can get to market much faster,” he said.

Yao and his lab, including research associate Yanliang Liang, who served as first author on the paper, began the work in 2013, after he was awarded $1 million from the Department of Energy’s Advanced Research Project Agency – Energy (ARPA-E) RANGE program to develop new battery technology. Other researchers involved in the project include Yan Jing, Saman Gheytani and Kuan-Yi Lee, all of UH, Ping Liu of the University of California-San Diego, and Antonio Faccheti of Northwestern University.

Energy storage is the key to wider adoption of electric cars, wind and solar power, along with other clean energy technologies. But the development of battery storage systems, which would be able to store energy until it is needed and then be recharged with additional generation, has been hampered by the lack of batteries that meet a variety of requirements: environmentally friendly, safe, inexpensive and long-lasting.

The researchers note in the study paper, “Aqueous rechargeable batteries featuring low-cost and nonflammable water-based electrolytes are intrinsically safe and (provide) robustness and cost advantages over competing lithium-ion batteries that use volatile organic electrolytes and are responsible for recent catastrophic explosions.”

But state-of-the-art aqueous rechargeable batteries have a short lifespan, making them unsuitable for applications where it isn’t practical to replace them frequently.

The stumbling block, Yao said, has been the anode, the portion of the battery through which energy flows. Existing anode materials are intrinsically structurally and chemically unstable, meaning the battery is only efficient for a relatively short time.

They worked with quinones, an earth-abundant organic material which Yan said costs just $2 per kilogram, demonstrating the material’s benefits in three formulations.

Liang explained the differing formulations offer evidence that the material is an effective anode for both acid batteries and alkaline batteries, such as those used in a car, as well as emerging aqueous metal-ion batteries. That means the quinones-based anode will work regardless of which technology dominates in the future, he said.

The new material also allows the batteries to work across temperature ranges, Liang said, unlike some conventional aqueous batteries, which are notoriously balky in cold weather.

Yao said consumers would quickly notice one key difference in this change to existing battery technology. “One of these batteries, as a car battery, could last 10 years,” he said. In addition to slowing the deterioration of batteries for vehicles and stationary electricity storage batteries, it also would make battery disposal easier because the material does not contain heavy metals.

The researchers have filed for three patents for the technology and hope to find partners to commercialize the technology.

This is quite an improvement across a wide spectrum of the battery market. Surely some enterprising and competitive manufacturer will pick this up and impress us with the longevity and performance.

Theorists at Caltech used quantum mechanics to predict what happens at atomic scales, while experimentalists at the Berkeley Lab used X-ray studies to analyze the steps in a chemical reaction returning CO2 to a fuel.

The research was started when a carbon dioxide experiment didn’t match with what theorists predicted, so the researchers went back to the drawing board and discovered something new.

The scientists’ ultimate goal is to convert carbon dioxide away from the atmosphere into beneficial liquid fuel. Currently, it is possible to make fuels out of CO2 – plants do it all the time in nature – but researchers are still trying to crack the problem of artificially producing the fuels at large enough scales to be useful.

This false-color image, produced with scanning electron microscopy, shows microscopic details on the surface of a copper foil that was used as a catalyst in a chemical reaction studied at Berkeley Lab’s Advanced Light Source. The scale bar represents 50 microns, or millionths of a meter.  Image Credit: Berkeley Lab, Click image for the largest view.

In a classic tale of science taking twists and turns before coming to a conclusion, two teams of researchers – one a group of theorists and the other, experimentalists – have worked together to solve a chemical puzzle that may one day lead to cleaner air and renewable fuel.

In a new study published in the journal Proceedings of the National Academy of Sciences, the researchers report the mechanics behind an early key step in artificially activating CO2 so that it can rearrange itself to become the liquid fuel ethanol.

William Goddard (PhD ’65), the Charles and Mary Ferkel Professor of Chemistry, Materials Science, and Applied Physics, who led the Caltech team said, “One of our tasks is to determine the exact sequence of steps for breaking apart water and CO2 into atoms and piecing them back together to form ethanol and oxygen. With these new studies, we have better ideas about how to do that.”

The metal copper is at the heart of the reaction for converting CO2 to fuel. Copper is a catalyst – a material used to activate and speed up chemical reactions and while it aids in the production of ethanol when exposed to CO2 and water, it is not efficient enough to make large quantities of ethanol. At Berkeley Lab, researchers exposed a thin foil sheet of copper to CO2 gas and water at room temperature. They found that the copper bound CO2 weakly and that adding water activated the CO2 by bending it into the shape needed to ultimately form the ethanol. However, when the theorists at Caltech used quantum mechanics and computer models to predict the atomic-level details of this reaction, they found that pure copper would not bind the CO2 and that water would not activate it.

This left both teams scratching their heads until they noticed that the copper in the experiments contained tiny amounts of oxygen beneath its surface. The theorists went back to their quantum mechanics equations, adding in a tiny amount of sub-surface oxygen, and were happy to find their calculations all agreed with the experiments.

Joint Center for Artificial Photosynthesis (JCAP) research scientist Hai Xiao said, “We do our experiments virtually in computers. And this allows us to trace how the electrons and atoms rearrange themselves in the reaction, and thus unravel the correlation between the fundamental structure and the activity.”

The theorists also predicted that when too much oxygen was present, the CO2 would not be activated. Indeed, when the experimentalists deliberately added extra oxygen into the mix, this prediction was confirmed.

Goddard noted, “This back and forth between theory and experiment is an exciting aspect of modern research and an important part of the JCAP strategy for making fuels from CO2,”

Ethan Crumlin, a scientist at Berkeley Lab explained subsequent X-ray studies helped further narrow down the role of the oxygen in the reaction. “Having oxygen atoms just beneath the surface – a suboxide layer – is a critical aspect to this. The X-ray work brought new clarity to determining the right amount of this subsurface oxygen – and its role in interactions with CO2 gas and water – to improve the reaction.”

The scientists say that the presence of the oxygen in the copper causes some of the copper to become positively charged and this, in turn, stabilizes the CO2 so that it can bind to water and take on the bent configuration essential to eventually making ethanol.

Based on the new findings, the Caltech researchers then used quantum mechanics to predict ways to make the reaction even more efficient. In a second paper published in PNAS, they report that a copper surface that is striped with both neutral and positively charged copper will better speed the reaction along. The team is now using this strategy, called a Metal-Embedded-in-Oxygen-Matrix (MEOM), to predict the best oxide material – either copper or something new – to place next to the neutral copper strips to achieve the fastest reaction.

“Quantum mechanics lets us find the best ways to arrange the atoms and takes us closer to the goal of converting carbon dioxide to fuels and other useful materials,” said Goddard.

The research group is part of the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, whose goal is to convert CO2 into high-value chemical products like liquid fuels. JCAP is led by Caltech in partnership with Berkeley Lab, the Stanford Linear Accelerator Center (SLAC), and UC campuses at San Diego and Irvine.

Hope for recycling CO2 looks better and better. The mere idea that CO2, seen by many as a problem. could be recycled, would be an absolute boon for the economy worldwide. Imagine CO2 was used and reused two, three or more times until it is wholly lost to the plant kingdom. Fuel stores of energy could be huge and much less expensive.

Go JCAP! There is a long way yet to research.

Stanford University scientists have developed a way to wirelessly deliver electricity to moving objects. The technology could one day charge electric vehicles and personal devices like medical implants and cell phones.

The press release makes the point if electric cars could recharge while driving down a highway, it would virtually eliminate concerns about their range and lower their cost, perhaps making electricity the standard fuel for vehicles. The scientists have overcome a major hurdle to such a future by wirelessly transmitting electricity to a nearby moving object.

Their results have been published in Nature.

Shanhui Fan, a professor of electrical engineering and senior author of the study said, “In addition to advancing the wireless charging of vehicles and personal devices like cellphones, our new technology may untether robotics in manufacturing, which also are on the move. We still need to significantly increase the amount of electricity being transferred to charge electric cars, but we may not need to push the distance too much more.”

The Stanford group built on existing technology developed in 2007 at MIT for transmitting electricity wirelessly over a distance of a few feet to a stationary object. In the new work, the team transmitted electricity wirelessly to a moving LED lightbulb. That demonstration only involved a 1-milliwatt charge, whereas electric cars often require tens of kilowatts to operate. The team is now working on greatly increasing the amount of electricity that can be transferred, and tweaking the system to extend the transfer distance and improve efficiency.

Wireless charging would address a major drawback of plug-in electric cars – their limited driving range. Tesla Motors expects its upcoming Model 3 to go more than 200 miles on a single charge and the Chevy Bolt, which is already on the market, has an advertised range of 238 miles. But electric vehicle batteries generally take several hours to fully recharge. A charge-as-you-drive system would overcome these limitations.

Fan explained, “In theory, one could drive for an unlimited amount of time without having to stop to recharge. The hope is that you’ll be able to charge your electric car while you’re driving down the highway. A coil in the bottom of the vehicle could receive electricity from a series of coils connected to an electric current embedded in the road.”

Some transportation experts envision an automated highway system where driverless electric vehicles are wirelessly charged by solar power or other renewable energy sources. The goal would be to reduce accidents and dramatically improve the flow of traffic while lowering “greenhouse gas” emissions.

Wireless technology could also assist GPS navigation of driverless cars. GPS is accurate up to about 35 feet. For safety, autonomous cars need to be in the center of the lane where the transmitter coils would be embedded, providing very precise positioning for GPS satellites.

Mid-range wireless power transfer, as developed at Stanford and other research universities, is based on magnetic resonance coupling. Just as major power plants generate alternating currents by rotating coils of wire between magnets, electricity moving through wires creates an oscillating magnetic field. This field also causes electrons in a nearby coil of wires to oscillate, thereby transferring power wirelessly. The transfer efficiency is further enhanced if both coils are tuned to the same magnetic resonance frequency and are positioned at the correct angle.

However, the continuous flow of electricity can only be maintained if some aspects of the circuits, such as the frequency, are manually tuned as the object moves. So, either the energy transmitting coil and receiver coil must remain nearly stationary, or the device must be tuned automatically and continuously – a significantly complex process.

To address the challenge, the Stanford team eliminated the radio-frequency source in the transmitter and replaced it with a commercially available voltage amplifier and feedback resistor. This system automatically figures out the right frequency for different distances without the need for human interference.

Graduate student Sid Assawaworrarit, the study’s lead author, explained, “Adding the amplifier allows power to be very efficiently transferred across most of the three-foot range and despite the changing orientation of the receiving coil. This eliminates the need for automatic and continuous tuning of any aspect of the circuits.”

Assawaworrarit tested the approach by placing an LED bulb on the receiving coil. In a conventional setup without active tuning, LED brightness would diminish with distance. In the new setup, the brightness remained constant as the receiver moved away from the source by a distance of about three feet. Fan’s team recently filed a patent application for the latest advance.

Fan said, “We can rethink how to deliver electricity not only to our cars, but to smaller devices on or in our bodies. For anything that could benefit from dynamic, wireless charging, this is potentially very important.”

Its interesting technology. Yet there are a couple very interesting questions. How to capitalize the costs of installing miles of charging coils and how to pay the bill for the power transferred. But in homes, businesses and factories this idea have good legs.

This is a long way off, one would think, for charging cars while traveling. Until batteries get much better for quick charging, or capacitors can hold long a charge enough and efficiently enough to quick charge and then charge the battery pack this technology has little practical use. Just don’t say “never”.


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