Ohio State University researchers have built a more efficient, more reliable potassium-oxygen battery, a step toward a potential solution for energy storage on the nation’s power grid and longer-lasting batteries in cell phones and laptops.

In a study published in the journal Batteries and Supercaps, researchers from Ohio State University detailed their findings centering around the construction of the battery’s cathode, which stores the energy produced by a chemical reaction in a metal-oxygen or metal-air battery. The finding, the researchers say, could make renewable energy sources like solar and wind more viable options for the power grid through cheaper, more efficient energy storage.

Vishnu-Baba Sundaresan, co-author of the study and professor of mechanical and aerospace engineering at Ohio State said, “If you want to go to an all-renewable option for the power grid, you need economical energy storage devices that can store excess power and give that power back out when you don’t have the source ready or working. Technology like this is key, because it is cheap, it doesn’t use any exotic materials, and it can be made anywhere and promote the local economy.”

Cost breakdown of K−O2 battery materials at the cell level for different electrolyte formulations: K−O2 battery with KPF6 electrolyte (left), K−O2 battery with KTFSI electrolyte (middle), and K−O2 battery with artificial anode SEI pre‐formed with KFSI electrolyte (right). Image Credit: Ohio State University. Click image for the largest view.

Renewable energy sources don’t emit carbon dioxide, so they don’t contribute to global warming – but they provide energy only when the sun is shining or the wind is blowing. In order for them to be reliable sources of power for a region’s energy grid, there needs to be a way to store excess energy gathered from sunshine and wind.

Companies, scientists and governments around the world are working on storage solutions, ranging from lithium-ion batteries – bigger versions of those in many electric vehicles – to giant batteries the size of a big-box store made using the metal vanadium.

Potassium-oxygen batteries have been a potential alternative for energy storage since they were invented in 2013. A team of researchers from Ohio State, led by chemistry professor Yiying Wu, showed that the batteries could be more efficient than lithium-oxygen batteries while simultaneously storing about twice the energy as existing lithium-ion batteries. But potassium-oxygen batteries have not been widely used for energy storage because, so far, they haven’t been able to recharge enough times to be cost-effective.

As teams tried to create a potassium-oxygen battery that could be a viable storage solution, they kept running into a roadblock: The battery degraded with each charge, never lasting longer than five or 10 charging cycles – far from enough to make the battery a cost-effective solution for storing power. That degradation happened because oxygen crept into the battery’s anode – the place that allows electrons to charge a device, be it a cell phone or a power grid. The oxygen caused the anode to break down, making it so the battery itself could no longer supply a charge.

Paul Gilmore, a doctoral candidate in Sundaresan’s lab, began incorporating polymers into the cathode to see if he might be able to protect the anode from oxygen. If he could find a way to do that, he thought, it would give potassium-oxygen batteries a shot at longer lives. It turned out he was right: The team realized that swelling in the polymer played a vital role in its performance. The key, Gilmore said, was finding a way to bring oxygen into the battery – necessary for it to work – without allowing oxygen to seep into the anode.

This design works a bit like human lungs: Air comes in to the battery through a fibrous carbon layer, then meets a second layer that is slightly less porous and finally ends at a third layer, which is barely porous at all. That third layer, made of the conducting polymer, allows potassium ions to travel throughout the cathode, but restricts molecular oxygen from getting to the anode. The design means that the battery can be charged at least 125 times – giving potassium-oxygen batteries more than 12 times the longevity they previously had with low-cost electrolytes.

The finding shows that this is possible, but the team’s tests haven’t proven that the batteries can be made on the scale necessary for power-grid storage, Sundaresan said. However, it does show potential.

Gilmore said potential may also exist for potassium-oxygen batteries to be useful in other applications.

“Oxygen batteries have higher energy density, which means they can improve the range of electric vehicles and battery life of portable electronics, for example, though other challenges must be overcome before potassium-oxygen batteries are viable for these applications,” he said.

And the finding offers an alternative to lithium-ion batteries and others that rely on cobalt, a material that has been called “the blood diamond of batteries.” The mining of the material is so troubling that major companies, including TESLA, have announced their plans to eliminate it from batteries entirely.

“It is very important that batteries intended for large-scale applications do not use cobalt,” Sundaresan said.

And it is also important that the battery can be made cheaply. Lithium-oxygen batteries – a possible energy storage solution that is widely considered one of the most viable options – can be expensive, and many rely on scarce resources, including cobalt. The lithium-ion batteries that power many electric cars cost around $100 per kilowatt hour starting at the materials level.

The researchers estimated that this potassium-oxygen battery will cost about $44 per kilowatt hour.

“When it comes to batteries, one size does not fit all,” Sundaresan said. “For potassium-oxygen and lithium-oxygen batteries, the cost has been prohibitive to use them as grid power backup. But now that we’ve shown that we can make a battery this cheap and this stable, then it makes it compete with other technologies for grid power backup.”

“If you have a smallish battery that is cheap, then you can talk about scaling it up. If you have a smallish battery that is $1,000 a pop, then scaling it up is just not possible. This opens the door for scaling it up.”

This post is derived from a well written press release that is quite good at explaining the situation. Batteries are subject to so many conditions it can get quite complex. Its been some years since we’ve seen a post on potassium-oxygen chemistry making this progress notable and welcome. One more 10 to 12 fold increase in useful cycles and this technology will take off. Driven by costs and other material issues will assure the market and the power availability will swamp many other chemistries we’re watching. It may take years and more intelligence, intuition and innovation, but it will come someday.

Congratulations are in order to the team, particularly to Paul Gilmore. Good work is an understatement, its a much more important milestone that’s been made.

Ruhr-University Bochum researchers are reporting on a new class of catalysts that is theoretically suitable for universal use.

Numerous chemical reactions relevant for the energy revolution are highly complex and result in considerable energy losses. This is the reason why energy conversion and storage systems or fuel cells are not yet widely used in commercial applications.

Michael Meischein in front of the sputter system in which nanoparticles are fabricated by co-deposition into an ionic liquid. Image Credit: Ruhr-University Bochum. Click image for the largest view.

Researchers at Ruhr-Universität Bochum (RUB) and colleagues at Max-Planck-Institut für Eisenforschung in Düsseldorf have now reported on a new class of catalysts that is theoretically suitable for universal use. These newly called high entropy alloys are formed by mixing close to equal proportions of five or more elements. They might finally push the boundaries of traditional catalysts that have been unsurpassable for decades.

The research team described their uncommon electrocatalytic working principles as well as their potential for systematic application in the journal ACS Energy Letters.

The material class of high entropy alloys features physical properties that have considerable potential for numerous applications. In oxygen reduction, they have already reached the activity of a platinum catalyst.

Professor Alfred Ludwig from the Chair of Materials for Microtechnology at RUB explained, “At our department, we have unique methods at our disposal to manufacture these complex materials from five source elements in different compositions in form of thin film or nanoparticle libraries.”

The atoms of the source elements blend in plasma and form nanoparticles in a substrate of ionic liquid. If the nanoparticles are located in the vicinity of the respective atom source, the percentage of atoms from that source is higher in the respective particle. “Very limited research has as yet been conducted into the usage of such materials in electrocatalysis,” said Ludwig.

This is expected to change in the near future. The researchers have postulated that the unique interactions of different neighboring elements might pave the way for replacing noble metals with equivalent materials.

Tobias Löffler, PhD researcher at the Center for Electrochemical Sciences at the RUB Chair of Analytical Chemistry said, “Our latest research has unearthed other unique characteristics, for example the fact that this class may also affect the inter-dependencies among individual reaction steps. Thus, it would contribute to solving one of the major problems of many energy conversion reactions, namely otherwise unavoidable great energy losses. The theoretical possibilities seem almost too good to be true.”

In order to promote rapid progress, the team from Bochum and Düsseldorf has described its initial findings with the aim of interpreting first characteristic observations, outlining the challenges, and putting forward first guidelines – all of which are conducive to advancing research.

Professor Wolfgang Schuhmann, Chair of Analytical Chemistry at RUB offered, “The complexity of the alloy is reflected in the research results, and many analyses will be necessary before one can assess its actual potential. Still, none of the findings to date precludes a breakthrough.”

The characterization of catalyst nanoparticles, too, is conducive to research. “In order to gain an indication of how, exactly, the activity is affected by the structure, high-resolution visualization of the catalyst surface on the atomic level is a helpful tool, preferably in 3D,” says Professor Christina Scheu from Max-Planck-Institut für Eisenforschung in Düsseldorf. Researchers have already demonstrated that this is an attainable goal – if not yet applied to this class of catalysts.

The question if such catalysts will facilitate the transition to sustainable energy management remains to be answered. “With our studies, we intend to lay the foundation for ongoing research in this field,” concluded the authors.

If all the assertions made by these authors are true or better, there may well be quite a fast paced evolution coming in energy and fuels in both costs and productivity. Both very good things, indeed.

Collaborators of three labs in Mexico have demonstrated an innovative nanodevice for harvesting solar energy.

I-V curves: (a) CDN – Ni-Pt, current in function of voltage (black line) and the electrical potential in 225 function of voltage (blue line). (b) EDN – Ni-Pt, current in function of voltage (black line) and the electrical 226 potential in function of voltage (blue line). Image Credit: Universidad Autonoma de San Luis Potos. Click image for the largest view.

The study paper has been published in the SPIE Journal of Nanophotonics. The paper, “Thermoelectric efficiency optimization of nanoantennas for solar energy harvesting,” reports that evolutive dipole nanoantennas (EDN) generate a thermoelectric voltage three times larger than the classic dipole nanoantenna.

Capturing visible and infrared radiation using nanodevices is an essential aspect of collecting solar energy: solar cells and solar panels are common devices that utilize nanoantennas, which link electromagnetic radiation to specific optical fields. The EDN antenna can be useful in many areas where high thermoelectric efficiency is needed from energy harvesting to applications across the aerospace industry.

Professor Ibrahim Abdulhalim, JNP Associate Editor, SPIE Fellow and a professor in the Electrooptics and Photonics Engineering Department at Ben-Gurion University of the Negev said, “The paper reports on a novel design and demonstration of a nanoantenna for efficient thermoelectric energy harvesting. They demonstrated thermoelectric voltage three times larger than a classical antenna. This type of antenna can be useful in many fields from harvesting of energy from waste heat, in sensing and solar thermal energy harvesting.”

The nanoantennas are bimetallic, using nickel and platinum, and were fabricated using e-beam lithography. The nanoantenna design was optimized using simulations to determine the distance between the elements. In comparing their thermoelectric voltage to the classic dipole nanoantenna, the EDNs were 1.3 times more efficient. The characterization was done using a solar simulator analyzing the I-V curves. The results indicate that EDN nanoantenna arrays would be good candidates for the harvesting of waste heat energy.

The article authors are Javier Mendez-Lozoya of Terahertz Science and Technology National Lab, Universidad Autonoma de San Luis Potosi, Mexico; Ramon Diaz de Leon-Zapata, of Tecnologico Nacional de Mexico, San Luis Potosi, Mexico; Edgar Guevara of Terahertz Science and Technology National Lab and Catedras CONACYT, Universidad Autonoma de San Luis Potosi, Mexico; Gabriel Gonzalez of Terahertz National Lab and Catedras CONACYT, Universidad Autonoma de San Luis Potosi, Mexico; and Francisco J. Gonzalez, of Terahertz Science and Technology National Lab, Universidad Autonoma de San Luis Potosi, Mexico.

One finds this as quite exciting right up to the word platinum. That element is the most expensive raw material on earth. But the methodology has a firm toehold now, with some hope that alternative materials can be made to meet or exceed these results. Congratulations are in order and hopes of God’s speed to this team. May the innovation continue!

A Helmholtz-Zentrum Berlin für Materialien und Energie team has succeeded in producing inorganic perovskite thin films at moderate temperatures using co-evaporation – making post-tempering at high temperatures unnecessary. The process makes it much easier to produce thin-film solar cells from this material. In comparison to metal-organic hybrid perovskites, inorganic perovskites are more thermally stable.

By co-evaporation of cesium iodide and lead iodide thin layers of CsPbI3 can be produced even at moderate temperatures. An excess of cesium leads to stable perovskite phases.  Image Credit: J. Marquez-Prieto. Helmholtz-Zentrum Berlin. Click image for the largest view.

The team’s research paper has been published in Advanced Energy Materials.

Teams all over the world are working intensively on the development of perovskite solar cells. The focus is on what are known as metal-organic hybrid perovskites whose crystal structure is composed of inorganic elements such as lead and iodine as well as an organic molecule.

Completely inorganic perovskite semiconductors such as CsPbI3 have the same crystalline structure as hybrid perovskites, but contain an alkali metal such as caesium instead of an organic molecule. This makes them much more stable than hybrid perovskites, but usually requires an extra production step at very high temperature – several hundred degrees Celsius.

For this reason, inorganic perovskite semiconductors have thus far been difficult to integrate into thin-film solar cells that cannot withstand high temperatures. A team headed by Dr. Thomas Unold has now succeeded in producing inorganic perovskite semiconductors at moderate temperatures so that they might also be used in thin-film cells in the future.

The physicists designed an innovative experiment in which they synthesized and analyzed many combinations of material within a single sample. Using co-evaporation of caesium-iodide and lead-iodide, they produced thin layers of CsPbI3, systematically varying the amounts of these elements, while the substrate-temperature was less than 60° Celsius.

Unold explained, “A combinatorial research approach like this allows us to find optimal production parameters for new material systems much faster than with the conventional approach that typically requires 100 samples to be produced for 100 different compositions.” Through careful analysis during synthesis and the subsequent measurements of the optoelectronic properties, they were able to determine how the composition of the thin film affects the material properties.

Their measurements show that the structural as well as important optoelectronic properties of the material are sensitive to the ratio of caesium to lead. Thus, excess caesium promotes a stable perovskite phase with good mobility and lifetimes of the charge carriers.

In cooperation with the HZB Young Investigator Group of Prof. Steve Albrecht, these optimized CsPbI3 layers were used to demonstrate perovskite solar cells with an initial efficiency of more than 12 % and stable performance close to 11% for over 1200 hours.

Unold said, “We have shown that inorganic perovskite absorbers might also be suitable for use in thin-film solar cells if they can be manufactured adequately. We believe that there is great room for further improvements.”

One day the perovskite solar panels are going to go on sale in a big way. Good efficiency and a low price will vastly increase the applicability.

University of Texas at Austin’s Texas Advanced Computing Center has shown that a voltage can be generated by harnessing differences in spin populations on a metal contact attached to a ferromagnetic material through a mechanism known as the Spin Hall effect. The researchers used supercomputers to identify various forms of cobalt oxide combined with nickel and zinc that show promise for thermoelectric generation by taking advantage of the Spin Hall effect.

“Do you feel the warmth coming off your computer or cell phone? That’s wasted energy radiating from the device. With automobiles, it is estimated that 60% of fuel efficiency is lost due to waste heat. Is it possible to capture this energy and convert it into electricity?” asked the press release.

Researchers working in the area of thermoelectric power generation say absolutely. But whether it can be done cost-effectively remains a question.

For now, thermoelectric generators are a rarity, used primarily in niche applications like space probes, where refueling is not a possibility. Thermoelectricity is an active area of research, particularly among automobile companies like BMW and Audi. However, to date, the cost of converting heat to electricity has proved to be more expensive than the electricity itself.

Diagram illustrating the substitutional effects of bivalent Zn and Ni cations on spin thermoelectric properties of Co3O4.  Image Credit: Nolan Hines, Gustavo Damis Resende, Fernando Siqueira Girondi, Shadrack Ofori-Boadi, Terrence Musho, Anveeksh Koneru. Click image for the largest view.

Anveeksh Koneru, a senior lecturer in mechanical engineering at The University of Texas Permian Basin (UTPB), is exploring a new method for capturing waste heat by harnessing the quantum mechanical motions of electrons in spin polarized materials.

In particle physics, spin is an intrinsic form of angular momentum carried by elementary particles, composite particles (hadrons), and atomic nuclei. Through a mechanism known as the Spin Hall effect, it has been shown that a voltage can be generated by harnessing differences in spin populations on a metal contact attached on a ferromagnetic material. First experimentally demonstrated by Japanese researchers in 2008, the idea has percolated through materials science for a while, but has yet to find its optimal form.

Koneru believes that, in cobalt oxide, he may have found the right material to harness the effect for energy production. An inorganic compound used in the ceramics industry to create blue colored glazes, and in water separation technologies, cobalt oxides possess the unique ability to accept substitute transition metal cations, which allows them to be mixed with nickel, copper, manganese, or zinc. These metals have magnetic properties that can increase the separation between electrons spinning up and down and improve the conversion of heat to electricity.

Koneru said, “The material should be a good electrical conductor, but a bad thermal conductor. It should conduct electrons, but not phonons, which are heat. To study this experimentally, we’d have to fabricate thousands of different combinations of materials. Instead, we’re trying to theoretically calculate what the optimal configuration of the material using substitutions is.”

Since 2018, Koneru has been using supercomputers at the Texas Advanced Computing Center (TACC) to virtually test the energy profiles of a variety of cobalt oxides with a range of substitutions.

“Each calibration takes 30 to 40 hours of computing time, and we have to study at least a 1,000 to 1,500 different configurations,” he explained. “It requires a huge computational facility and that’s what TACC provides.”

Koneru, along with UTPB graduate students Gustavo Damis Resende, Nolan Hines, and a collaborator from West Virginia University, Terence Musho, presented their initial findings on the thermoelectric capacity of cobalt oxides at the Materials Research Society Spring Meeting in Phoenix, Arizona, on April 22.

The researchers studied 56-atom unit cells of three configurations of cobalt oxide, tuned by substitutions of nickel and zinc, to attain optimal thermoelectric performance. They used a software package known as Quantum ESPRESSO to calculate physical characteristics for each configuration. These include:

– the band gap: the minimum energy required to excite an electron to a state where it conducts energy; the lattice parameter: the physical dimensions of cells in a crystal lattice;
– the effective mass of conduction electrons: the mass that a particle seems to have when responding to force;
– and the spin polarization: the degree to which the spin is aligned with a given direction.

These fundamental properties were then used to perform conventional charge and spin transport calculations, which tells the researchers how well a configuration of the cobalt oxide can turn heat into electricity.

According to the researchers, the method developed in this research can be applied to other interesting thermoelectric materials with semiconducting and magnetic properties, making it broadly useful for the materials science community.

As a PhD student at West Virginia University, Koneru had access to large supercomputers to conduct his research. Although UTPB does not have such resources locally, he was able to tap into the advanced computing systems and services of TACC through the UT Research Cyberinfrastructure (UTRC) initiative, which, since 2007, has provided researchers at any of the University of Texas System’s 14 institutions access to TACC’s resources, expertise, and training.

As part of the UTRC initiative, TACC staff serve as liaisons, visiting UT System’s 14 campuses, offering training and consultation, and introducing researchers the resources available to them. When TACC researcher Ari Kahn visited UTPB, he met Koneru and encouraged him to compute at TACC.

Since then, Koneru has been using Lonestar5, a system exclusively for UT System researchers, for his work. Though still in their early stage, the results so far have been promising.

“I’m excited because we could clearly see spin polarization when cobalt oxide spinels were substituted with nickel. That’s a good sign,” he said. “We’re seeing that one particular configuration has a higher split in band-gap, something that’s surprising and we have to explore further. And all the calibrations are converging, which shows they’re reliable.”

Once he identifies the optimal material for waste heat conversion, Koneru hopes to engineer a paste that could be applied to the tailpipe of a vehicle, converting waste heat into electricity to power a car’s electrical systems. He estimates that such a device could cost less than $500 per vehicle and could reduce greenhouse gas emissions by hundreds of millions of tons annually.

“With the recent advances in nanofabrication, and computational calibrations for nanomaterials, spin-thermal materials can play a vital role in energy conversion in the future,” he said.

TACC enables Koneru to speed through a large number of possible material configurations so that when it is time to test them experimentally, the number of candidates will be manageable.

“TACC is such a highly useful system with personnel that can guide you if any problems arise,” Koneru said. “If faculty or students are interested in research that requires computational facilities, TACC is the right option to choose. It provides resources and expertise for free. It’s a great enabler for whatever you’re passionate about. ”

“It’s our mission to encourage researchers all across the State to use TACC resources to make amazing discoveries that cannot be made in the lab or using local clusters,” said TACC’s Ari Khan. “Dr. Koneru’s research is a great example of such a project that could have a major impact on air pollution and global warming.”

This is so early that the first material testing has yet to take place. Yet in the face of the incredibly enormous heat losses from energy production and use today, the effort is akin to finding the mother load of all energy sources. High efficiency and low cost could double the energy available or perhaps even more. Gods’s speed to these folks.


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