Last year, Oak Ridge National Laboratory (ORNL) announced that researchers had “successfully demonstrated that lithium-sulfur battery technology can indeed outdo lithium-ion on several fronts.” Theoretically, lithium-sulfur batteries could be four times as energy dense as today’s lithium-ion batteries, but that promise had yet to be demonstrated. ORNL took initial steps toward that goal, and within the last few months researchers at Vanderbilt University have shown a strong lead in forming lithium-sulfur batteries with commercial potential. Echoing work done at Sakti3, ORNL researchers demonstrated an all-solid-state lithium-sulfur cell, addressing flammability issues shared by batteries with solid electrolytes. Using lithium polysulfidophosphates (LPSPs) in the cathode, and which have ionic conductivities eight times higher than that of lithium sulfide (Li2S) the team coupled that with a lithium anode to create “an energy-dense, all solid battery.” Energy density was a noteworthy 1,200 mili-Amp-hours per gram, about 7 to 8.5 times that of conventional lithium batteries. A number of blogs repeated the slightly overheated lines …
Load-Bearing Supercapacitors
What if your battery served also as a wing or a fuselage? Several current efforts converge on creating batteries or supercapacitors that could function as structural elements in electric vehicles. We’ve reported on this before, with efforts by Dr. Emil Greenhalgh at Imperial College London and associated work by Volvo to make car components from the type of energy storing sandwich structure he developed. Your editor’s article on the “Grand Unified Airplane” in the July 2013 issue of Kitplanes magazine advanced the idea that such structures, coupled with graphene’s projected capabilities to collect solar energy, could lead to a self-powering aircraft. (In researching the current entry, he found that his idea had been done at model scale by BAE.) Reports from two universities show that others are working toward making that dream less than an idle fantasy. Researchers at Vanderbilt University are making headway toward creating a “Multifunctional Load-Bearing Solid-State Supercapacitor,” as titled in the American Chemical Society’s journal, Nano …
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 …
Giving Power Walking a Whole New Meaning
Georgia Institute of Technology researchers have developed a self-charging power cell that uses a piezoelectric membrane to convert mechanical energy to chemical energy, then stores that energy until it can be released as en electrical current. Combining the power generator with the energy storage device, this hybrid is claimed to be more efficient than systems with separate generators and batteries. When the piezoelectric membrane is flexed, it moves lithium ions in the power cell from one side of the cell to the other. Membranes in shoe heels and soles could produce power when a person walked, powering small electronic devices such as calculators or cell phones. Zhong Lin Wang, a Regents professor in the School of Materials Science and Engineering Georgia Tech, explains the distinguishing feature of his team’s innovation. “People are accustomed to considering electrical generation and storage as two separate operations done in two separate units. We have put them together in a single hybrid unit to create a …
That’s No Yolk!
Dr. Cui is at it again! In a seemingly endless stream of announcements, his work with silicon anodes keeps promising improvements in battery capacity and longevity. The Stanford professor and his team, Stanford’s National Accelerator Laboratory (Formerly the Stanford Linear Accelerator Center), and the Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory all published papers on their latest joint accomplishment. Conceptual drawing of silicon filling carbon shell, TEM photo of actual expansion, and life cycle analysis for yolk-shell batteries Expansion and contraction of anodes and cathodes during charging and discharging of batteries causes flexing and eventual breakdown of a battery’s internal components. Cui and other researchers have tried various strategies to mitigate or eliminate this flexing, but the latest tactic seems to promise longer battery life and greater power and energy. Calling it a “yolk-shell structure,” researchers seal commercially available single silicon nanoparticles in “conformal, thin, self-supporting carbon shells, with rationally-designed void space between the particles and the …