Oxis Batteries to Fly in Two Airplanes

Dean Sigler Announcements, Batteries, Electric Powerplants, Sustainable Aviation Leave a Comment

While we wait yet another five years for commercial development of each newly announced but promising battery chemistry, one company has its cells ready to fly in Bye Aerospace’s eFlyer 2 and in Texas Aircraft’s Colt S-LSA.  Oxis Energy has managed to leapfrog lithium-ion makers with its lithium-sulfur battery packs packing 400 Watt-hours per kilogram.  Considering the best announced pack-level li-ion performance has been 260 W-hr/kg, the leap is significant. Batteries, for now, are at the heart of electric aircraft.  Until Doc Brown’s Flux Capacitor or a hydrogen fuel cell with Dollar Tree refills comes along, batteries are battling it out for our airborne dollars.  Lithium-ion remains in the forefront, with Tesla staging its shareholders’ meeting and its long-anticipated “Battery Day” on September 22.  Elon Musk has been dangling the promise of a million-mile battery for the last year, which may tie in with Chinese manufacturer Contemporary Amperex Technology (CATL).   According to Bloomberg, CATL’s, “Chairman and founder Zeng Yuqun said …

Rumpled Cathodes Benefit Lithium Sulfur Batteries

Dean Sigler Batteries, Sustainable Aviation Leave a Comment

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.  This demonstrated capacity and longevity is something other experimenters with lithium sulfur batteries have tried unsuccessfully to achieve. Green Car Reports quotes Jiangxuan Song, one of the researchers on the techniques used. “Lithium–sulfur battery cells using these wrinkled graphene sheets …

Cambridge’s “Ultimate” Battery? Wait 10 Years and See

Dean Sigler Batteries, Electric Aircraft Materials, Electric Powerplants Leave a Comment

Cambridge University researchers claim to have successfully demonstrated how several of the problems impeding the practical development of the so-called “ultimate” battery, in this case a lithium-oxygen unit, could be overcome.  They make some pretty impressive claims, saying they’ve developed a working laboratory demonstrator with “very high” energy density – comparable to that of gasoline and with greater than 90-percent efficiency, and the ability to be recharged more than 2,000 times, or 5-1/2 years with a complete cycle and recharge every day. A lithium-oxygen or lithium-air battery of this type would allow an uninterrupted drive between London and Edinburgh on a single charge, about 415 miles, over 100 miles greater than the top mileages promised by Tesla and GM at this point. Researchers add the promise of one-fifth the cost and one-fifth the weight of currently available batteries – a touchstone for electric aircraft designers, and close to the goals U. S. Energy Secretary Steven Chu asked for three years …

EAS IX: Short Circuiting Batteries on Purpose

Dean Sigler Electric Aircraft Components, Electric Powerplants, Sustainable Aviation Leave a Comment

Recent news from the world of insurance claims adjustors brings us back to ways inspired battery designers might reduce or eliminate certain types of claims, and make electric flight safer. Even when international agreements don’t make progress along those lines. Insurance Claims and international Agreements With recent news of Federal Aviation Administration interest in lithium-ion batteries arising from fires caused by thermal runaways, shipments of large numbers of batteries may be banned.  Claims Journal, an insurance industry news line, quotes Angela Stubblefied, an FAA hazardous materials safety official, as saying, “’We believe the risk is immediate and urgent.’ She cited research showing the batteries can cause explosions and fires capable of destroying a plane. “FAA tests show that even a small number of overheating batteries emit gases that can cause explosions and fires that can’t be prevented by current fire suppression systems. Airlines flying to and from the U.S. that accept lithium battery shipments carry 26 million passengers a year, …

Salting the Battery

Dean Sigler Electric Powerplants, Sustainable Aviation Leave a Comment

Ideally, battery materials should be abundant, cheap, and safe.  NaCl (salt) seems to manage three out of three of these, but can it manage the energy and power density of less abundant and more expensive materials such as lithium? Faradion, an English enterprise specializing in “advanced energy storage solutions,” thinks that the salt of the earth may indeed be part of the secret sauce in their new battery.  Initial applications will probably be in large energy-storage systems associated with renewable energy, but forward-looking statements (we used to call them predictions) show the potential for lighter, smaller batteries that could compete with lithium-ion cells. Since the introduction of new technology does not usually come from a single source, Faradion is partnered with co-funders Innovate UK, the UK’s innovation agency; Williams Advanced Engineering and the University of Oxford. The group is building 3 Amp-hour prismatic cells “containing Faradion’s novel cell chemistry, and are being incorporated into battery packs by Williams.”  This will …

Fast-Charging Batteries with a “Holey” Electrode

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Replacing the graphite used in conventional battery electrodes with “a network of tin-oxide nanoparticles” could reduce battery charging time from hours to minutes.  An energy storage device combining the advantages of batteries and capacitors is a long-term goal for researchers, and a multi-national discovery may help expedite that goal. Graphite anodes and cathodes, as used in most lithium batteries today, limit storage capacities to 372 milliampere hours per gram (mA·h/g), the theoretical maximum of graphite. By comparison, an Energizer Ultimate Lithium AA battery holds about 3,000 mAh and weighs 14.5 grams (or about 207 mA h/g). A typical rechargeable AA battery holds only 750 to 900 mAh (around 54 to 64 mA h/g).  This limit “hinders significant advances in battery technology,” according to Vilas Pol, Associate Professor of Chemical Engineering at Purdue University. There, Pol, postdoctoral research associate Vinodkumar Etacheri, and other researchers internationally have experimented with a “porous interconnected” tin-oxide-based anode, giving twice the theoretical charging capacity of graphite.  Not …

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 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 …

The New Mythbusters: Slow Charging May Not Make Batteries Last Longer

Dean Sigler Electric Powerplants, Sustainable Aviation Leave a Comment

For the last 60 years, your editor remembers the oft-repeated advice from garage mechanics and now lithium-ion advocates that slow charging is the way to make your batteries last for many cycles.  Where does this put Tesla, for instance, with its 20-minute Superchargers?  Are you damaging your expensive cells by being in a hurry? In yet another example of counter-intuitive thinking at work, researchers at SLAC, the National Accelerator Laboratory at located on the Stanford University campus have challenged several tenets of conventional battery wisdom.  According to PC World, their work, “published on Sunday in the Journal, Nature Materials, challenges the commonly held notion that slowly charging a battery helps prolong its life and that it’s damaging to a battery if a large amount of energy is withdrawn in a short time.” William Chueh, a senior author of the paper and researcher at the Stanford Institute for Materials and Energy Sciences (SIMES), told the magazine, “’We’ve always thought of a …

An Electrolyte Gel Sandwich

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Sekisui Chemical Co., Ltd. makes a wide variety of plastics, films, and active chemical components.  Whipping up something light and powerful in their kitchen must often be a matter of tossing available ingredients into a new recipe.  In this case, they’ve come up with something unique and potentially highly useful. Their research and development center director Satoshi Uenoyama announced “a high-capacity film-type lithium-ion battery “using a coating process that has simultaneously tripled its capacity (compared to other Sekisui Chemical products), increase its safety (as a result of standard safety testing, e.g. no problems with nail penetration tests or crush tests) and speeded up production by ten times (compared to other Sekisui Chemical products).” The company continues comparisons with its products, suggesting lithium-ion conductivity for the new battery is 10 times that of other Sekisui Chemical products.  They claim “enhanced safety” through the use of a high-performance gel-type electrolyte, which because of its high viscosity, can be spread onto the battery’s film materials as part of …

Getting Batteries in Line

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In another bid to create the much-hoped-for 10X batteries, researchers at North Carolina State University are rolling their own. As noted in many articles, lithium batteries infused with silicon have a bad habit of swelling and contracting as they charge and discharge, pulverizing the silicon eventually.  Depending on the surrounding materials, the destruction can take place fairly quickly, leading to reduced cycle life for the battery. North Carolina scientists are fighting to extend battery life, though, with what they call “A Novel Nano-architecture for Flexible Lithium Ion Battery Electrodes,” part of the title of their paper in the journal Advanced Materials. Many battery electrodes are some form of graphite composite, and the impetus to wrap these anodes or cathodes in silicon has strong motivation.  “Putting silicon into batteries can produce a huge increase in capacity—10 times greater,” Dr. Philip Bradford, assistant professor of textile engineering, chemistry and science at NC State says. “But adding silicon can also create 10 times …