Low Cost Batteries for Renewable Energy Sources

As the world builds out ever larger installations of wind and solar power systems, the need is growing fast for economical, large-scale backup systems to provide power when the sun is down and the air is calm. Today’s lithium-ion batteries are still too expensive for most such applications, and other options such as pumped hydro require specific topography that’s not always available. Now, researchers at MIT and elsewhere have developed a new kind of battery, made entirely from abundant and inexpensive materials, that could help to fill that gap. The new battery architecture, which uses aluminum and sulfur as its two electrode materials, with a molten salt electrolyte in between, is described today in the journal Nature, in a paper by MIT Professor Donald Sadoway, along with 15 others at MIT and in China, Canada, Kentucky, and Tennessee.

I wanted to invent something that was better, much better, than lithium-ion batteries for small-scale stationary storage, and ultimately for automotive [uses],” explains Sadoway, who is the John F. Elliott Professor Emeritus of Materials Chemistry. In addition to being expensive, lithium-ion batteries contain a flammable electrolyte, making them less than ideal for transportation. So, Sadoway started studying the periodic table, looking for cheap, Earth-abundant metals that might be able to substitute for lithium. The commercially dominant metal, iron, doesn’t have the right electrochemical properties for an efficient battery, he says. But the second-most-abundant metal in the marketplace — and actually the most abundant metal on Earth — is aluminum. “So, I said, well, let’s just make that a bookend. It’s gonna be aluminum,” he says.

Source: https://news.mit.edu/

Nanoparticles Help to Produce Rapid, Efficient Hydrogen from Water

UCSC chemists developed a simple method to make aluminum nanoparticles that split water and generate hydrogen gas rapidly under ambient conditions. Aluminum is a highly reactive metal that can strip oxygen from water molecules to generate hydrogen gas. Its widespread use in products that get wet poses no danger because aluminum instantly reacts with air to acquire a coating of aluminum oxide, which blocks further reactions.

For years, researchers have tried to find efficient and cost-effective ways to use aluminum’s reactivity to generate clean hydrogen fuel. A new study by researchers at UC Santa Cruz shows that an easily produced composite of gallium and aluminum creates aluminum nanoparticles that react rapidly with water at room temperature to yield large amounts of hydrogen. The gallium was easily recovered for reuse after the reaction, which yields 90% of the hydrogen that could theoretically be produced from reaction of all the aluminum in the composite.

We don’t need any energy input, and it bubbles hydrogen like crazy. I’ve never seen anything like it,” said UCSC Chemistry Professor Scott Oliver.

Oliver and Bakthan Singaram, professor of chemistry and biochemistry, are corresponding authors of a paper on the new findings, published February 14 in Applied Nano Materials.

The reaction of aluminum and gallium with water has been known since the 1970s, and videos of it are easy to find online. It works because gallium, a liquid at just above room temperature, removes the passive aluminum oxide coating, allowing direct contact of aluminum with water. The new study, however, includes several innovations and novel findings that could lead to practical applications.

https://news.ucsc.edu/

Bionic Eye With Better Vision Than Humans

The world’s first 3D artificial eyeball — capable of outperforming the human eye in some ways — may help droves of people who are partially or fully blind in as little as five years, according to experts.

Researchers from Hong Kong University of Science and Technology have devised an electrochemical eye whose structure and performance mimic those of the ones humans are born with.

The device design has a high degree of structural similarity to a human eye with the potential to achieve high imaging resolution when individual nanowires are electrically addressed,” researchers of Hong Kong University of Science and Technology wrote in a paper published in the journal Nature.

The device converts images through tiny sensors that mirror the lightdetecting photoreceptor cells in a human eyeThe Sun reported. Those sensors reside within a membrane made of aluminum and tungsten which is shaped into a half sphere for the purpose of mimicking a human retina.

Source:  https://www.nature.com/
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How To Etch A ‘Perfect’ Solar Energy Absorber

The University of Rochester research lab that recently used lasers to create unsinkable metallic structures has now demonstrated how the same technology could be used to create highly efficient solar power generators.

In a paper in Light: Science & Applications, the lab of Chunlei Guo, professor of optics also affiliated with the Department of Physics and Astronomy and the Material Sciences Program, describes using powerful femto-second laser pulses to etch metal surfaces with nanoscale structures that selectively absorb light only at the solar wavelengths, but not elsewhere.

A regular metal surface is shiny and highly reflective. Years ago, the Guo lab developed a black metal technology that turned shiny metals pitch black.

 

But to make a perfect solar absorber,” Guo says, “We need more than a black metal and the result is this selective absorber.”

This surface not only enhances the energy absorption from sunlight, but also reduces heat dissipation at other wavelengths, in effect, “making a perfect metallic solar absorber for the first time,” Guo says. “We also demonstrate solar energy harnessing with a thermal electric generator device.

This will be useful for any thermal solar energy absorber or harvesting device,” particularly in  places with abundant sunlight, he adds.

The researchers experimented with aluminum, copper, steel, and tungsten, and found that tungsten, commonly used as a thermal solar absorber, had the highest solar absorption efficiency when treated with the new nanoscale structures. This improved the efficiency of thermal electrical generation by 130 percent compared to untreated tungsten.

Co-authors include Sohail Jalil, Bo Lai, Mohamed Elkabbash, Jihua Zhang, Erik M. Garcell, and Subhash Singh of the Guo lab.

Source: https://www.rochester.edu/