Silicon, Sulfur and 3D graphene Makes High-Performance Battery

Dean Sigler Batteries, Electric Aircraft Materials, Sustainable Aviation 0 Comments

Lithium-sulfur batteries display winning qualities, such as low production cost, environmental friendliness, and high energy density.  Researchers usually give up, or look elsewhere, when the materials’ poor cycle life and loss of active materials on both anode and cathode show up. Researchers at Beihang University in Beijing report developing “a new Li-sulfur battery using honeycomb-like sulfur copolymer uniformly distributed onto 3D graphene (3D cpS-G) networks for a cathode material and a 3D lithiated Si-G network as anode.”  They report “a high reversible capacity of 620 milli-Amp hours per gram, [and an] ultrahigh energy density of 1,147 Watt-hours per kilogram (based on the total mass of cathode and anode), good high-rate capability and excellent cycle performance over 500 cycles (0.028% capacity …

Rumpled Cathodes Benefit Lithium Sulfur Batteries

Dean Sigler Batteries, Sustainable Aviation 0 Comments

We like to think of things inside batteries as neatly organized, but Pennsylvania State University researchers may have come up with a less tidy way of making cathodes. Researchers synthesized “highly crumpled” nitrogen-doped graphene (NG) sheets with “ultrahigh pore volume” and large surface area (1,158 square meters– 12,465 square feet or about one-third the area of a football field) per gram.  This large area and high porosity “enable strong polysulfide adsorption and high sulfur content for use as a cathode material in Li-sulfur batteries.”  Interwoven rather than stacked, the wrinkled material provides ample room for “nitrogen-containing active sites.” The batteries, according to the researchers, “achieved” a high capacity of 1,226 milliamp-hours per gram and 75-percent capacity retention after 300 cycles.  …

Lithium-Sulfur Cells Wrapped in Graphene

Dean Sigler Electric Powerplants, Sustainable Aviation 0 Comments

Graphene is science fiction made real – a one-atom thick layer of hexagonal arrays of carbon which weigh next to nothing and are stronger than any other material on earth.  Wrap a layer of this stuff around “a novel multifunctional sulfur electrode that combines an energy storage unit and electron/ion transfer networks,” and you get “an extremely promising electrode structure design for rechargeable lithium-sulfur batteries.” Lithium-sulfur batteries have the promise of reaching a theoretical specific energy density “approaching 2,600 Watt-hours per kilogram (Wh kg-1),” compared to currently available specific energy densities for lithium-ion cells of 130-220 Wh kg-1. Researchers led by Dr. Vasant Kumar at the University of Cambridge and Professor Renjie Chen at the Beijing Institute of Technology worked …

400 Watt-Hours per Kilogram by 2014

Dean Sigler Electric Powerplants, Sustainable Aviation 0 Comments

On its web site, the company boasts, “OXIS Energy is leading the World with its latest cell Energy Density and Capacity,” and proceeds to announce that it’s “developed its largest Lithium Sulfur cell achieving in excess of 300 [Watt-hours per kilogram]. This outperforms Lithium ion technology that has dominated the performance battery market for many years. In addition OXIS has achieved an increase in cell capacity to a 25 Amp-hour (Ah) cell – a world first.”  They’re working toward a 33Ah cell. Claiming a twelve-fold improvement in the last 18 months, OXIS, a British battery manufacturer, says it has the confidence to “achieve a cell capacity of 33Ah by mid 2015.”  The firm has hopes of energy densities “in excess …

Lithium Sulfur Batteries – Energy Storage at New Heights

Dean Sigler Electric Powerplants, Sustainable Aviation 2 Comments

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 …

Hybrid Batteries in Hybrid Vehicles?

Dean Sigler Electric Powerplants, Sustainable Aviation 0 Comments

Frances White of the Pacific Northwest National Laboratory (PNNL) reports that a new anode quadruples the life of a test lithium-sulfur battery and could lead to much lower costs for electric vehicles and large-scale energy storage. This blog has noted that many researchers focus on development of better cathodes, or anodes, or electrolytes exclusively, neglecting a more holistic, or whole battery approach to their delving.  PNNL scientists have a reason for focusing on anodes, having found that a “battery with a dissolved cathode can still work.” What dissolves the electrodes in a battery?  “Unwanted side reactions,” according to PNNL, cause the battery’s sulfur-containing cathode to disintegrate slowly and form polysulfide molecules that dissolve into the battery’s electrolyte liquid.  This becomes …

Longer Life and More Energy

Dean Sigler Electric Powerplants, Sustainable Aviation 0 Comments

Who wouldn’t want both?  Researchers in Germany and America are making great inroads on lithium battery energy density, while  adding some hope that batteries may someday outlast the vehicle in which they are installed. Ulm, Germany, where the Berblinger Competition encourages economical flight, may be a resource for making such flight possible.  The Zentrum für Sonnenenergie- und WasserstoffForschung Baden-Württemberg (Centre for Solar Energy and Hydrogen Research Baden-Württemberg, ZSW), has announced what they claim to be world-beating cells in terms of cycle life. Dr. Margret Wohlfahrt-Mehrens, Head of the Accumulator Material Research Department in Ulm reports, “After 10,000 complete charging and discharging cycles with a complete charge and discharge cycle per hour (2 C), our lithium batteries still have more than …

Oxis Energy and Lithium Sulfur Batteries

Dean Sigler Electric Powerplants, Sustainable Aviation 0 Comments

Taking one last look at 2011’s fifth annual Electric Aircraft Symposium, your editor regrets the fits and starts in its coverage. Next week, we’ll begin looking at the extraordinary presentations from this year’s gathering. Huw W. Hampton-Jones from Oxis Energy, a British company developing a Lithium Sulfur battery, claimed his firm’s “technology is based around the use of Lithium Sulphur to produce batteries which are superior in terms of energy, weight, cycle life, costs, ageing and safety.” Lithium sulfur is well known in military circles for providing primary (non-rechargeable) power to field operations.  Perlan I flew with SAFT 5590 primary batteries, partly because of their superior energy density compared to lithium-ion cells, and partly because of their greater resistance to …

QinetiQ Zephyr Breaks Official Record for Solar-Powered Endurance

Dean Sigler Electric Powerplants, Sustainable Aviation 0 Comments

According to BBC News and GlobalFlight.com, QinetiQ’s Zephyr, a 22.5 meter (72 feet) unmanned, solar-powered aircraft has been in the air for more than a week over the Yuma, Arizona Proving Grounds, and program managers intend to keep it there for a total time of at least fourteen days.  Having flown since 6:40 a.m. July 9, its endurance is now four times that of any other unmanned aerial vehicle.   A US Global Hawk holds the current official world endurance record for an unmanned aerial vehicle (UAV) of 30 hours, 24 minutes.  Zephyr’s record is being certified by the Federation Aeronautique Internationale, the world air sports federation. Jon Saltmarsh, Zephyr’s project manager, says the craft, “Is basically the first ‘eternal aircraft,’”  a name once given to …