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White Graphene Helps Batteries Keep Their Cool in High Temperatures

While this blog has devoted a fair amount of attention to the use of nanomaterials to improve the charge capacity of electrodes in Li-ion batteries, mentions of research into the use of nanomaterials for electrolytes and separators has been more scarce on these pages. Nonetheless, a lot of research is going on with the aim of improving the thermal stability of Li-ion batteries’ electrolytes and separators.

Now, researchers at Rice University are combining their work on improving the thermal stability of electrolytes with research into separators made from a new material: hexagonal boron nitride. In research described in the journal Advanced Energy Materials, the researchers were able to produce a Li-ion battery that operated for more than a month at temperatures as high as 150 degrees Celsius (302 °F) with very little loss of efficiency.

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Graphene Filter Could Make Wireless Data Transmission 10 Times Faster

Researchers at Ecole Polytechnique Fédérale de Lausanne (EPFL) and the University of Geneva in Switzerland have developed a graphene filter for microchips that could potentially lead to wireless transmission rates 10 times as fast what chips deliver today.

In research described in the journal Nature Communications, the Swiss researchers actually fabricated what is known as a non-reciprocal isolator. The isolator filters backward radiation, preventing waves from being reflected back towards their source.

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Wafer-scale Nanotube Film Is Finally Here

Single-walled carbon nanotubes (SWCNTs) used to be the darling of those who were looking for an alternative to silicon in digital electronics. The first SWCNT-based transistors were fashioned almost twenty years ago, but scaling up the use of SWCNTs since then to very large scale integration (VLSI) processes has remained elusive.

There were two persistent problems with SWCNTs that led to much of the research community pursuing graphene instead of SWCNTs as the next great post-silicon hope: an inconsistency between semiconducting and metallic nanotubes and the frustration of trying to get all of the nanotubes to align on a wafer.

Now researchers at Rice University claim that they have struck upon a method that produces a uniform and wafer-scale film of highly aligned and densely packed SWCNTs that may finally deliver on the long-promised potential of SWCNTs.

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2-D Boron Is an Intrinsic Superconductor

Just as we were getting confirmation that graphene could be coaxed into behaving as a superconductor, we now get research out of Rice University indicating that the two-dimensional version of boron may be the only flatlands material that is an intrinsic superconductor.

Researchers at Rice, led by Boris Yakobson, have used computer calculations to determine that boron is a natural low-temperature superconductor, and may, in fact, be the only 2-D material with this intrinsic property.

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World's Smallest Diode Is Made of DNA

Scientists have now created what they say is the world's smallest diode, one the size of a single (rather short) molecule of a DNA. This work could help spur development of DNA components for molecular electronics, its creators claim.

Diodes—also known as rectifiers—allow electric current to flow in just one direction. More than 40 years ago, scientists proposed miniaturizing diodes and other electronic components down to the size of single molecules, an idea that eventually helped give birth to the field of molecular electronics, which could help push computing beyond the limits of conventional silicon devices. [See “Whatever Happened to the Molecular Computer?IEEE Spectrum, October 2015]

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Light Could Become the Dominant Form of Heat Transfer

We know that when you touch a hot cup of tea it can warm your hands. That’s heat conduction: Two surfaces of different temperatures make physical contact and heat is transferred from one to the other. We are also pretty aware of convective heat transfer, though it may not be quite as simple. In convection, the heat transfer occurs when a fluid—this can be air, some other gas, or even a liquid—is caused to move away from a source of heat and in the process carries energy with it. For instance, above the hot surface of a stove, the air being warmed expands, becomes less dense than the surrounding cold air, and rises.

The reason for this elementary explanation of heat transfer is to set them apart from another means of thermal energy transfer. Objects can also transfer heat to their surroundings using light, but that method of heat exchange has always been thought to be very weak compared with conduction and convection. Now, in collaborative research among researchers at Columbia, Cornell, and Stanford, they discovered that we just weren’t doing it right. Their conclusion: light could become the most dominant form of heat exchange between objects.

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Silicon and Graphene Combo Finally Achieve Lithium-Ion Battery Greatness

Silicon, graphene, and sometimes the two of them combined together have all been suggested as potential replacements for graphite in the electrodes of lithium-ion batteries.

While all three of these options bring attractive properties to the table—most importantly, a very high theoretical capacity—those properties are lost in the real world. Silicon electrodes crack and break after just a short number of charge/discharge cycles. Meanwhile, the use of graphene on electrodes is limited because graphene’s attractive surface area is only possible in single stand-alone sheets, which don’t provide enough volumetric capacitance. Layer the graphene sheets on top of each other to gain that volumetric capacity, and you begin to lose that attractive surface area.

Now researchers at Kansas State University (KSU) claim to have developed a technique that uses silicon oxycarbide that makes the combination of silicon and graphene achieve its expected greatness as an electrode material.

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UK's National Graphene Institute Kerfuffle Gets the PR Treatment

Earlier this month, the UK newspaper The Sunday Times broke a story  claiming that researchers at the University of Manchester and the National Graphene Institute (NGI) were reluctant to occupy the NGI’s new $71 million research building. Their reason: fear that the work they produce there would be taken by a foreign company.

Since that news story broke, damage control from the NGI, the University of Manchester, and BGT Materials, the company identified in the Times article, has been coming fast and furious. Even this blog’s coverage of the story has gotten comments from representatives of BGT Materials and the University of Manchester.

There was perhaps no greater effort in this coordinated defense than getting Andre Geim, a University of Manchester researcher who was a co-discoverer of graphene, to weigh in. Geim, typically reluctant to speak with the press, offered a full-throated defense of his employer and its partners, saying that the UK has not lost out on graphene-related tech jobs, nor is the new research institute close to empty.

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Nanocones Funnel Light So Solar Cells Soak Up More Sun

Researchers at the Royal Melbourne Institute of Technology (RMIT University) in Australia have created an entirely new nanostructure they have dubbed a “nanocone”. It combines the upside-down physics of topological insulators with the easier-to-explain process of plasmonics. The result is a nanomaterial that can be used with silicon-based photovoltaics to increase their light absorption properties.

Topological insulators have the peculiar property of behaving as insulators on the inside but conductors on the outside and plasmonics exploits the oscillations in the density of electrons that are generated when photons hit a metal surface. What the RMIT researchers have done by bringing these worlds together is create a plasmonic nanostructure that has a core-shell structure that lends itself to being topological insulator.

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Crumpling Graphene Repeatedly Adds a New Wrinkle

Over the last year, research is increasingly showing that if you crumple graphene so that it has wrinkles, the material takes on attractive new properties. For instance, researchers at RIKEN in Japan discovered last year that by forming wrinkles in graphene you can restrict the movements of electrons to create a junction-like structure that changes from a zero-gap conductor to a semiconductor and back to zero-gap conductor.

This Japanese research and others like it that have looked at creating wrinkles in graphene have only examined the potential of wrinkling the material once.

Now research out of Brown University has looked to see what happens when you wrinkle graphene repeatedly.

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Nanoclast

IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

 
Editor
Dexter Johnson
Madrid, Spain
 
Contributor
Rachel Courtland
Associate Editor, IEEE Spectrum
New York, NY
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