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November 6th, 2012

Other materials science stories that may be of interest

Published on November 6th, 2012 | By: pwray@ceramics.org


While manganese (blue) fills out this lithium ion battery nanoparticle evenly, nickel (green) clumps in certain regions, interfering with the material’s smooth operation. Credit: Chongmin Wang; PNNL.

Lots of good work going on out there. Here are some samples:

Nickelblock: An element’s love-hate relationship with battery electrodes

Anyone who owns an electronic device knows that lithium-ion batteries could work better and last longer. Now, scientists examining battery materials on the nanoscale reveal how nickel forms a physical barrier that impedes the shuttling of lithium ions in the electrode, reducing how fast the materials charge and discharge. Published in Nano Letters, the research also suggests a way to improve the materials. The researchers, led by Pacific Northwest National Laboratory’s Chongmin Wang, created high-resolution 3D images of electrode materials made from lithium-nickel-manganese oxide layered nanoparticles, mapping the individual elements. These maps showed that nickel formed clumps at certain spots in the nanoparticles. A higher magnification view showed the nickel blocking the channels through which lithium ions normally travel when batteries are charged and discharged. “We were surprised to see the nickel selectively segregate like it did. When the moving lithium ions hit the segregated nickel rich layer, they essentially encounter a barrier that appears to slow them down,” says Wang. “The block forms in the manufacturing process, and we’d like to find a way to prevent it.” Researchers have known for a long time that adding nickel improves how much energy the electrode can hold, battery qualities known as capacity and voltage. But scientists haven’t understood why the capacity falls after repeated usage—a situation consumers experience when a dying battery holds its charge for less and less time.

Virginia Tech, India center to launch solar, windmill research project

A new Virginia Tech research center, set to open later this fall in the state of Tamil Nadu in southeast India, will mobilize an engineering team to refine and adapt windmills and solar panels for use in households in rural India. Two years ago, Virginia Tech announced an agreement with private-sector partner MARG Swarnabhoomi to establish the Virginia Tech, India campus. MARG Swarnabhoomi has committed $1.8 million for laboratory build-out, which will equal or exceed facilities at the Blacksburg-based Center for Energy Harvesting Materials and Systems, directed by Shashank Priya of the College of Engineering. “We will start recruiting graduate students in India to work on the project immediately, while our 6,000-square-foot lab space is being fully outfitted,” says Roop Mahajan, director of the Institute for Critical Technology and Applied Science at Virginia Tech. The new research center will be called the VT, India Institute for Critical Technology and Applied Science Innovation Center. The center will be inside MARG Swarnabhoomi’s Amrita Research Park, where ocean breezes are conducive to windmill research, Mahajan says. Windmills are being designed to work in areas of low and variable wind speed; similarly, the solar panels are being designed to work in low-light conditions, he says.

Stanford scientists build the first all-carbon solar cell

Stanford University scientists have built the first solar cell made entirely of carbon, a promising alternative to the expensive materials used in photovoltaic devices today. The results are published in the online edition of the journal ACS Nano. Unlike rigid silicon solar panels that adorn many rooftops, Stanford’s thin film prototype is made of carbon materials that can be coated from solution. The coating technique also has the potential to reduce manufacturing costs, said Stanford graduate student Michael Vosgueritchian, co-lead author of the study with postdoctoral researcher Marc Ramuz and professor Zhenan Bao. The Bao group’s experimental solar cell consists of a photoactive layer, which absorbs sunlight, sandwiched between two electrodes. In a typical thin film solar cell, the electrodes are made of conductive metals and indium tin oxide.

Mobile bulk bag filling system has metal detection, tilt-down feeder

A new mobile bulk bag filling system from Flexicon Corp. features an integral metal detector/separator and a tilt-down conveyor/feeder for dust-free filling at multiple locations. Integral to the system is a patented twin-centerpost bulk bag filler said to maximize strength and improve accessibility to bag hooks while simplifying construction and reducing cost. The system detects metal in the free-fall stream of material entering the filler and then ejects it through a chute that discharges into a removable drum at the rear of the unit. The filler is also equipped with: fill head height adjustment to accommodate all popular bag sizes; inflatable cuff to seal the bag inlet spout; blower to remove bag creases prior to filling; load cells for filling by weight; vent port for dust-free air displacement during filling; pneumatically retractable bag hooks; and automated vibratory densification/deareation system to maximize capacity and stabilize the bag for storage or shipment. The first bulk bag filler to receive USDA acceptance, it is constructed of 316 stainless steel, finished to sanitary standards and configured with full-length forklifting tubes allowing it to be moved throughout the plant.

The most important education technology in 200 years

What has been the single biggest innovation in education? If you come up blank, you’re supposed to. The question is a gambit used by Anant Agarwal, the computer scientist named this year to head edX, a $60 million MIT-Harvard effort to stream a college education over the Web, free, to anyone who wants one. His point: it’s rare to see major technological advances in how people learn. Agarwal believes that education is about to change dramatically. The reason is the power of the Web and its associated data-crunching technologies. Thanks to these changes, it’s now possible to stream video classes with sophisticated interactive elements, and researchers can scoop up student data that could help them make teaching more effective. The technology is powerful, fairly cheap, and global in its reach. EdX has said it hopes to teach a billion students.



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