Two different lines of research in Korea and Australia seem to be heading toward practical supercapacitors with energy densities approaching the lower end of battery technology while offering better charging efficiency and extended lifetimes. Santhakumar Kannappan, a researcher at the Gwangju Institute of Science and Technology in Korea has led a team who reduced graphene oxide particles with hydrazine in water, then agitated the slurry with ultrasound. This produces a “highly porous form of graphene that has a huge internal surface area,” equivalent to a basketball court for every gram. They pack the resulting powder into a coin-shaped cell, dry it at 140° C and a pressure of 300 kilograms per centimeter (4,267 pounds per square inch) for five hours. Electrodes made this way and saturated in EBIMF 1 M electrolyte have a specific capacitance of 150 Farads per gram, an energy density of 64 Watt-hours per kilogram and a current density of 5 Amps per gram. MIT’s Technology Review …
Going Over to the Dark Side
The University of Texas at Austin’s press release spells out the quantum-like behavior of photons striking solar cells, and provides some insight into why obtaining higher efficiencies so far has perplexed researchers. “AUSTIN, Texas — The efficiency of conventional solar cells could be significantly increased, according to new research on the mechanisms of solar energy conversion led by chemist Xiaoyang Zhu at The University of Texas at Austin. “Zhu and his team have discovered that it’s possible to double the number of electrons harvested from one photon of sunlight using an organic plastic semiconductor material. “’Plastic semiconductor solar cell production has great advantages, one of which is low cost,’ said Zhu, a professor of chemistry. ‘Combined with the vast capabilities for molecular design and synthesis, our discovery opens the door to an exciting new approach for solar energy conversion, leading to much higher efficiencies.’” Zhu and his team published their discovery December 16 in the journal Science, under the title …
99.99 Percent Air, Thinner Than a Human Hair
ScienceDaily reports that, “A team of researchers from UC Irvine, HRL Laboratories and the California Institute of Technology have developed the world’s lightest material — with a density of 0.9 mg/cc — about one hundred times lighter than Styrofoam™.” Their findings appear in the Nov. 18 issue of Science. Looking a bit like a jacks matrix, this “micro-lattice” cellular architecture consists of 99.99 percent air and a lattice of interconnected hollow tubes with a wall thickness 1,000 times thinner than a human hair, according to Dr. Tobias Schaedler of HRL. Despite its extreme lightness, the advanced material is not flimsy. Squeezing it to 50 percent of its original dimensions does not destroy the lattice. Instead, it handles the high strain and resumes its original size and shape, the ultimate memory metal. Energy absorption capabilities are also high, as are its possibilities for use in “battery electrodes and acoustic, vibration or shock energy absorption,” according to Science Daily. The new material …