Dr. Yi Cui seems to get inspiration from food. A few years ago, his research team came up with a “yolk-shell structure” that helped contain the high amount of lithium that silicon anodes were able to absorb. That battery design promised much, and an embellishment of that design seems to hold even greater promise. His newest effort, working at Stanford University with the Department of Energy’s SLAC National Accelerator Laboratory, features an electrode “designed like a pomegranate – with silicon nanoparticles clustered like seed in a tough carbon rind.” This approach, according to its inventors, overcomes several remaining obstacles to the use of silicon in a new generation of lithium-ion batteries. Yi said the battery’s efficiency and longevity are promising. “Experiments showed our pomegranate-inspired anode operates at 97 percent capacity even after 1,000 cycles of charging and discharging, which puts it well within the desired range for commercial operation.” Cui’s team has been working on preventing anode breakup for the …
Nanopaper Solar Cells – Finest Wood Pulp in the World
Nanopapers are, like the paper we use daily, made from wood pulp, but in this case reduced to nano-sized lengths and formed into “a network of nanofibrillated (tangled) cellulose (NFC).” This tangled network, a seemingly impenetrable mass, is surprisingly transparent, and the paper’s increased light scattering makes it 90 to 95-percent transparent (a counter-intuitive thought). Earlier discoveries showed that coating the paper with carbon nanotubes “made the paper very strong and highly conductive, which could allow it to be used for printed electronics (such as circuit boards) and in products that require a lightweight construction.” Extracting NFC from ordinary paper fibers is a time and energy intensive process, so the next batch of nanopaper won’t use these fibers, instead “detangling” or “unraveling” the cellulose through a process called tempo-oxidation to make “nanoribbons.” Nanopaper made from these ribbons is 91 percent transparent, has its surface oxidized to increase strength, and has a layer of silver nanowires for conductivity. A TEMPO (Tetramethylpiperidinyloxy) NaBr-NaClO oxidation …
Cheap and Dirty Fuel Cells – Good News for Hydrogen
Hydrogen fuel cells would be just about the most wonderful power producers in the world if they weren’t so expensive and so finicky about their diet of hydrogen. Their catalysts, usually made of costly platinum, can be destroyed by impurities in the gas. Making high-purity hydrogen is an exacting task and adds to the expense of operation. Two studies by scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory; one in conjunction with researchers at South Korea’s Ulsan National Institute of Science and Technology (UNIST), Korea Institute of Energy Research (KIER), show that it may be commercially possible to make less expensive catalysts with available materials, and in one case, use “dirty” hydrogen that would otherwise destroy fuel cells. The reduced price of making such hydrogen would further add to operational economies. Green Car Congress reports that Brookhaven and UNIST have discovered, “a new family of non-precious metal catalysts based on ordered mesoporous porphyrinic carbons (M-OMPC) with high …
Crushed, Rolled, or Slivered, Silicon Boosts Batteries
Two different Rice University research teams are applying different but related approaches to using silicon in lithium batteries to make them more energy dense and longer-lived. One team recently came up with a paint-on lithium battery, announced a way to use otherwise waste silicon by crushing it and spreading it on anodes in their test batteries. This has implications for manufacturing because of the simplicity of the process. Dvice.com gives one hint as to why this might be good. “In lithium-ion batteries, for example, the anode is usually graphite, because it works well and is cheap. “You know what else is cheap? Silicon. The Earth is 28% silicon, making it the second most abundant crustal element by mass after oxygen. And it makes a fantastic battery anode, too: it can hold 10x more lithium ions than graphite. However, if you cram it full of all those ions, it swells in size [up to three times] and will damage itself, which …