April 28, 2016 | Leave a Comment
University of California, Irvine (UCI) researchers have invented a nanowire-based battery material that can be recharged hundreds of thousands of times. Scaled up and marketable the tech would get us closer to a battery that would never require replacement. The breakthrough work could lead to commercial batteries with greatly lengthened lifespans for computers, smartphones, appliances, cars and spacecraft.
The study leader, UCI doctoral candidate Mya Le Thai, cycled the testing electrode up to 200,000 times over three months without detecting any loss of capacity or power and without fracturing any nanowires. The findings have been published in the American Chemical Society’s Energy Letters.
The UCI researchers solved the recharge cycling problem by coating a gold nanowire in a manganese dioxide shell and encasing the assembly in an electrolyte made of a Plexiglas-like gel. The combination is reliable and resistant to failure.
Reginald Penner, chair of UCI’s chemistry department said, “Mya was playing around, and she coated this whole thing with a very thin gel layer and started to cycle it. She discovered that just by using this gel, she could cycle it hundreds of thousands of times without losing any capacity.”
“That was crazy,” he added, “because these things typically die in dramatic fashion after 5,000 or 6,000 or 7,000 cycles at most.”
The researchers think the goo plasticizes the metal oxide in the battery and gives it flexibility, preventing cracking.
“The coated electrode holds its shape much better, making it a more reliable option,” Thai said. “This research proves that a nanowire-based battery electrode can have a long lifetime and that we can make these kinds of batteries a reality.”
Scientists have long sought to use nanowires in batteries. Thousands of times thinner than a human hair, they’re highly conductive and feature a large surface area for the storage and transfer of electrons. However, these filaments are extremely fragile and don’t hold up well to repeated discharging and recharging, or cycling. In a typical lithium-ion battery, they expand and grow brittle, which leads to cracking.
The study was conducted in coordination with the Nanostructures for Electrical Energy Storage Energy Frontier Research Center at the University of Maryland, with funding from the Basic Energy Sciences division of the U.S. Department of Energy.
This is just the kind of thing that is “disruptive” to an existing industry, not that there is any battery tech that isn’t getting disruption right along. But this news is likely to attract the attention of battery researchers worldwide and set off an hunt for better and cheaper versions
Out in the real world a lithium battery is doing pretty well in holding up to buyer expectations at 1-2000 charging cycles. Most electric vehicles are projected in a few years to need a new battery pack. Now suppose that instead of a few years a car needs a new battery pack – the battery pack outlasts several cars.
The economic impact would be enormous. Congratulations to Mya Le Thai, your humble writer’s nomination for the Nobel prize in “serendipity”.
April 27, 2016 | Leave a Comment
Researchers at Tohoku University have announced a new thermoelectric device using cutting edge thermoelectric conversion technology. Thermoelectric conversion technology converts energy abandoned as waste heat back to electric power that could potentially save lost energy.
The new technology, known as the spin Seebeck effect, has conversion efficiency 10 times higher than the conventional method. Although conventional spin Seebeck thermoelectric devices have the advantage of low manufacturing costs and high versatility and durability, their energy conversion efficiency remains an uneconomic disappointment.
Soichi Tsumura, General Manager, IoT Device Research Laboratories, NEC Corporation said, “We have improved the conversion efficiency of this spin Seebeck thermoelectric device by more than 10 times because of its newly developed material and device structure. Furthermore, devices made of flexible material, such as resin, have been achieved using a manufacturing process that does not require high-temperature heat treatment.”
“The conversion efficiency of this new spin thermoelectric device has been improved by almost one million times when compared to the earliest device, and has taken an important step towards practical use as a generator element. The achievement of practical use as a heat flux sensor is also in sight,” said Tsumura.
These results were achieved as part of the “Saitoh Spin Quantum Rectification Project” led by Tohoku University Professor Eiji Saitoh. It is funded by the Exploratory Research for Advanced Technology program of the Japan Science and Technology Agency.
The three parties aim to further the research and development of technologies to generate electricity from the large amount of waste heat emitted by things such as plants, data centers and vehicles.
Lets hope the team hit the “home run” as the waste heat loss is a paradoxical problem of escaping energy and wasted hard cash. It a problem very much in need of a good solution.
Utah State University researchers have announced a light-driven process that uses photochemical energy to replace adenosine triphosphate to convert dinitrogen, the form of nitrogen found in the air, to ammonia fertilizer.
All living things require nitrogen for survival, but the world depends on only two known processes to break nitrogen’s ultra-strong bonds to allow conversion to a form humans, animals and plants can consume. One is a natural, bacterial process on which farmers have relied since the dawn of agriculture. The other is the century-old Haber-Bösch process, which revolutionized fertilizer production and spurred unprecedented growth of the global food supply.
Utah State University biochemist Lance Seefeldt points out, “We live in a sea of nitrogen, yet our bodies can’t access it from the air. Instead, we get this life-sustaining compound from protein in our food.”
Now Seefeldt and his colleagues have announced a light-driven process that could, once again, revolutionize agriculture, while reducing the world food supply’s dependence on fossil fuels and taking out some of the Haber-Bösch’s vast use of natural gas.
The research team, which includes USU’s Seefeldt, Derek Harris, Andrew Rasmussen and Nimesh Khadka; Katherine A. Brown and Paul W. King of Colorado’s National Renewable Energy Laboratory; Molly Wilker, Hayden Hamby and Gordana Dukovic of the University of Colorado and Stephen Keable and John Peters of Montana State University.
Seefeldt, a professor in USU’s Department of Chemistry and Biochemistry and an American Association for the Advancement of Science Fellow said, “Our research demonstrates photochemical energy can replace adenosine triphosphate, which is typically used to convert dinitrogen, the form of nitrogen found in the air, to ammonia, a main ingredient of commercially produced fertilizers.”
Any way you slice it, he said, nitrogen fixation is an energy-intensive process.
“The Haber-Bösch process currently consumes about two percent of the world’s fossil fuel supply,” Seefeldt said. “So, the new process, which uses nanomaterials to capture light energy, could be a game-changer.”
NREL research scientist Katherine A. Brown explained, “Using light directly to create a catalyst is much more energy efficient. This new ammonia-producing process is the first example of how light energy can be directly coupled to dinitrogen reduction, meaning sunlight or artificial light can power the reaction.”
The research adds to the knowledge base of energy-efficient production of ammonia holding promise not only for food production, but also for development of technologies that enable use of environmentally cleaner alternative fuels, including improved fuel cells to store solar energy.
In addition to its practical applications, the research sheds light on fundamental aspects of how bacterial enzymes known as nitrogenases function; an area of chemistry Seefeldt has studied for nearly two decades.
Plant biology and food and fuel producing agriculture are directly coupled to ammonia based nitrogen for food and fuels. Worldwide the cracking of natural gas to acquire the hydrogen for ammonia and for process heat is a substantial load on the natural gas supply. Little is projected on the human starvation effects if the environmentalist crowd were to succeed in limiting natural gas supplies.
This team’s work is a breakthrough. A new field has opened up. Congratulations. But, there is still much to do.
April 21, 2016 | Leave a Comment
Australian National University (ANU) physicists have discovered radical new properties in a nanomaterial which could one day harvest heat in the dark and turn it into electricity. The research team has demonstrated a new artificial material, or metamaterial, that glows in an unusual way when heated. The metamaterial opens new possibilities for highly efficient thermophotovoltaic cells.
The findings could drive a revolution in the development of cells which convert radiated heat into electricity, known as thermophotovoltaic cells.
Dr Sergey Kruk from the ANU Research School of Physics and Engineering said, “Thermophotovoltaic cells have the potential to be much more efficient than solar cells. Our metamaterial overcomes several obstacles and could help to unlock the potential of thermophotovoltaic cells.”
Thermophotovoltaic cells have been predicted to be more than two times more efficient than conventional solar cells. They do not need direct sunlight to generate electricity, and instead can harvest heat from their surroundings in the form of infrared radiation. They can also be combined with a burner to produce on-demand power or can recycle heat radiated by hot engines.
The team’s metamaterial, made of tiny nanoscopic structures of gold and magnesium fluoride, radiates heat in specific directions. The geometry of the metamaterial can also be tweaked to give off radiation in specific spectral range, in contrast to standard materials that emit their heat in all directions as a broad range of infrared wavelengths. This makes it ideal for use as an emitter paired with a thermophotovoltaic cell.
The project started when Dr Kruk predicted the new metamaterial would have these surprising properties. The ANU team then worked with scientists at the University of California Berkeley, who have unique expertise in manufacturing such materials.
“To fabricate this material the Berkeley team were operating at the cutting edge of technological possibilities,” Dr Kruk said. “The size of individual building block of the metamaterial is so small that we could fit more than twelve thousand of them on the cross-section of a human hair.”
The key to the metamaterial’s remarkable behavior is its novel physical property, magnetic hyperbolic dispersion. Dispersion describes the interactions of light with materials and can be visualized as a three-dimensional surface representing how electromagnetic radiation propagates in different directions. For natural materials, such as glass or crystals the dispersion surfaces have simple forms, spherical or ellipsoidal.
The dispersion of the new metamaterial is drastically different and takes hyperbolic form. This arises from the material’s remarkably strong interactions with the magnetic component of light.
The efficiency of thermovoltaic cells based on the metamaterial can be further improved if the emitter and the receiver have just a nanoscopic gap between them. In this configuration, radiative heat transfer between them can be more than ten times more efficient than between conventional materials.
This team’s work may offer a huge improvement and extend the applicability of heat recovery as well as solar efficiency. This field is opening up now and will over time change our perception of heat and solar energy resources.
April 20, 2016 | 2 Comments
Pacific Northwest National Laboratory (PNNL) researchers have made an unexpected discovery leading to a rechargeable battery that’s as inexpensive as conventional car batteries, but has a much higher energy density. The new battery could become a cost-effective, environmentally friendly alternative for storing renewable energy and supporting the power grid.
The team identified this energy storage gem after realizing the new battery works in a different way than they had assumed. The journal Nature Energy has published their paper that describes the battery.
PNNL Fellow Jun Liu, the paper’s corresponding author starts the explanation, “The idea of a rechargeable zinc-manganese battery isn’t new; researchers have been studying them as an inexpensive, safe alternative to lithium-ion batteries since the late 1990s. But these batteries usually stop working after just a few charges. Our research suggests these failures could have occurred because we failed to control chemical equilibrium in rechargeable zinc-manganese energy storage systems.”
After years of focusing on rechargeable lithium-ion batteries, researchers are used to thinking about the back-and-forth shuttle of lithium ions. Lithium-ion batteries store and release energy through a process called intercalation, which involves lithium ions entering and exiting microscopic spaces in between the atoms of a battery’s two electrodes.
This concept is so ingrained in energy storage research that when PNNL scientists, collaborating with the University of Washington, started considering a low-cost, safe alternative to lithium-ion batteries – a rechargeable zinc-manganese oxide battery – they assumed zinc would similarly move in and out of that battery’s electrodes.
After a battery of tests, the team was surprised to realize their device was undergoing an entirely different process. Instead of simply moving the zinc ions around, their zinc-manganese oxide battery was undergoing a reversible chemical reaction that converted its active materials into entirely new ones.
Liu and his colleagues started investigating rechargeable zinc-manganese batteries because they are attractive on paper. They can be as inexpensive as the lead-acid batteries because they use abundant, inexpensive materials (zinc and manganese). And the battery’s energy density can exceed lead-acid batteries. The PNNL scientists hoped they could produce a better-performing battery by digging deeper into the inner workings of the zinc-manganese oxide battery.
So they built their own battery with a negative zinc electrode, a positive manganese dioxide electrode and a water-based electrolyte in between the two. They put small, button-sized test batteries through the wringer, repeatedly charging and discharging them. As others had found before them, their test battery quickly lost its ability to store energy after just a few charging cycles. But why?
To find out, they first performed a detailed chemical and structural analysis of the electrolyte and electrode materials. They were surprised to not find evidence of zinc interacting with manganese oxide during the battery’s charge and discharge processes, as they had initially expected would happen. The unexpected finding led them to wonder if the battery didn’t undergo a simple intercalation process as they had previously thought. Perhaps the zinc-manganese battery is less like a lithium-ion battery and more like the traditional lead-acid battery, which also relies on chemical conversion reactions.
Digging deeper, they examined the electrodes with several advanced instruments with a variety of scientific techniques, including Transmission Electron Microscopy, Nuclear Magnetic Resonance and X-Ray Diffraction. The instruments used were located at both PNNL and the Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science user facility located at PNNL. Combining these techniques revealed manganese oxide was reversibly reacting with protons from the water-based electrolyte, which created a new material, zinc hydroxyl sulfate.
Typically, zinc-manganese oxide batteries significantly lose storage capacity after just a few cycles. This happens because manganese from the battery’s positive electrode begins to sluff off, making the battery’s active material inaccessible for energy storage. But after some manganese dissolves into the electrolyte, the battery gradually stabilizes and the storage capacity levels out, though at a much lower level.
The team used the new knowledge to prevent this manganese sluff-off. Knowing the battery underwent chemical conversions, they determined the rate of manganese dissolution could be slowed down by increasing the electrolyte’s initial manganese concentration.
So they added manganese ions to the electrolyte in a new test battery and put the revised battery through another round of tests. This time around, the test battery was able to reach a storage capacity of 285 milliAmp-hours per gram of manganese oxide over 5,000 cycles, while retaining 92 percent of its initial storage capacity.
Liu sums up, “This research shows equilibrium needs to be controlled during a chemical conversion reaction to improve zinc-manganese oxide battery performance. As a result, zinc-manganese oxide batteries could be a more viable solution for large-scale energy storage than the lithium-ion and lead-acid batteries used to support the grid today.”
The team will continue their studies of the zinc-manganese oxide battery’s fundamental operations. Now that they’ve learned the products of the battery’s chemical conversion reactions, they will move on to identify the various in-between steps to create those products. They will also tinker with the battery’s electrolyte to see how additional changes affect its operation.
That’s classic research. Congratulations to the team for getting the basic answers and making a potentially useful product from something not so very useful.