With recent news of a solid-state battery coming for the labs of Yi Cui, a second solid-state solution seems to follow from another Stanford Laboratory.  The All-Electron Battery, funded at least partly by an ARPA-E grant that underwrote the program from 2010 to 2012, has fostered a startup, QuantumScape.

Starting from the stated need for a battery “with twice the energy storage of today’s state-of-the-art Li-Ion battery at 30% of the cost,” ARPA-E worked with the premise that Stanford was “developing an all-electron battery that would create a completely new class of energy storage devices for EVs. Stanford’s all-electron battery stores energy by moving electrons rather than ions. Electrons are lighter and faster than the ion charge carriers in conventional Li-Ion batteries. Stanford’s all-electron battery also uses an advanced structural design that separates critical battery functions, which increases both the life of the battery and the amount of energy it can store. The battery could be charged 1000s of times without showing a significant drop in performance.”

The proposal’s Impact Summary noted that, “If successful, Stanford would create an entirely new class of EV batteries capable of storing much more energy than traditional Li-Ion batteries, facilitating widespread EV use.”

Stanford's patent drawing shows encapsulated layers with solid electrolyte and catholyte, an electrolyte surrounding the cathode, and which should be a solid, rather than liquid material

Stanford’s patent drawing shows encapsulated layers with solid electrolyte and catholyte, an electrolyte surrounding the cathode, and which should be a solid, rather than liquid material

As reported here last year, QuantumScape, despite the lack of substantive material on its all-too-reticent web site, attracted the attention of Volkswagen, which according to Bloomberg, will decide to go forward with more than a five-percent interest in the startup company.

“Volkswagen AG plans to decide in the first half of this year whether new battery technology under development at U.S. startup QuantumScape Corp. is ready for use in its electric cars.

“’The technology’s potential to boost the range of battery-powered vehicles is compelling and tests are progressing,’ VW Chief Executive Officer Martin Winterkorn said outside a press conference in Stuttgart, Germany, on Tuesday.

“’I was there last year,’ Winterkorn said. ‘Progress has been made,’ and the company will be able to determine how to proceed by July.”

As with all other automakers in the EV marketplace, VW needs to achieve Corporate Average Fuel Economy (CAFE) standards in America, and rigorous CO2 and other emissions requirements in the European Union.   Despite lagging electric car sales, the carmakers need to press on to avoid penalties and meet ever tougher goals.

Bloomberg reports that Winterkorn said in November that he sees “great potential” in the new power-storage technology, with up to 700 kilometers (430 miles) range for unspecified VW models, more than three times that of the electric version of the VW Golf.   This would be half again as high as Tesla’s advertised Model S range of 270 miles.

Since QuantumScape’s web presence includes only pretty pictures and some contact information, speculation abounds on what’s in the potential VW battery package.  Professor Doctor Winterkorn’s address at the Science Award for Electrochemistry ceremonies on November 6, 2014, gives some clues as to why VW is interested.

As noted before in this blog, Winterkorn highlighted VW’s massive research and development investments.

“At our Group we have some 44,000 R&D experts in 20 countries.   We are spending roughly 13 billion Dollars on R&D – each year.  And we are making sure that all the relevant drive-train technologies are as efficient and economical as possible. Including, of course, our combustion engines which have great potential.”

Some of that potential seems to be near term, and other elements might be further in the future.  The structure of his talk makes it difficult to define the actual timeline, other than a few tantalizing hints.

“Take energy density, for example: Increasing the specific energy of lithium-ion cells to as much as 380 Wh/l will reduce driving range drawbacks. With a higher nickel content (editor’s italics), much more will be feasible. But we also need to intensify basic research into batteries with an even greater specific energy, such as solid-state batteries. I see great potential in this new technology, possibly boosting the range to as much as 700 kilometers (1,000 Wh/l).  Another matter is cost: Lowering the price of battery cells to 100 euros per kilowatt hour would significantly increase the market potential of electric vehicles.  And if we also improve reliability and battery lifespan, customer acceptance will grow fast.”

Several questions arise from his remarks.  Why is the reference to higher nickel content important?  Will this be part of a 700-kilometer battery?

Cleantechnica.com speculates about QuantumScape’s offerings.  Founded by Stanford researchers in 2010, the company’s lithium batteries focus on fundamental disruption in the energy storage sector (italics theirs).  Offerings might be commercial versions of all-electron batteries developed by Dr. Frederich Prinz and his team, with leadership by CEO Jagdeep Singh, described by Cleantechnica as “a Silicon Valley rock star,” with a “solid track record in cutting edge tech.”

Prinz’s work with an “all electron battery effect,” related “to the use of inclusions embedded in a dielectric structure between two electrodes of a capacitor. Electrons can tunnel through the dielectric between the electrodes and the inclusions, thereby increasing the charge storage density relative to a conventional capacitor.

Another patent describes the use of antiperovskite materials, those sharing a crystal structure similar to naturally occurring perovskite, a calcium titanium oxide.  According to the patent, “The formation and use thereof of antiperovskite material enables a metallic lithium anode, which increases the capacity and therefore the energy density of any lithium-based electrochemical storage device.”

This adds up to a battery with a solid-state electrolyte rather than a conventional liquid electrolyte.  Such batteries could be more energy dense and much safer, not being loaded with flammable liquids.  They could also survive thousands of charge-discharge cycles.  VW looks to hit a 100 euro per kilowatt-hour goal for such energy storage.  If Prinze, QuantumScape and VW can all come together (remembering Dr. Winterkorn’s  promised decision by July) this might lead to exciting battery developments in Silicon Valley on an aggressive schedule.

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Siemens Makes a Big, Light Motor

Its 14 kilogram (30.8 pound), 85 kilowatt (114 horsepower) motor already graces the nose of the PIpistrel WattsUp, and Siemens seems to have expanded its aeronautical offerings with its new 50 kilogram (110 pound), 260 kilowatt (348.5 hp.) unit.  According to Dr. Frank Anton, Head of eAircraft at Siemens Corporate Technology, the new motor “make[s] it possible to build series hybrid-electric aircraft with four or more seats.”

Dr. Frank Anton with 50 kilogram, 250 kW motor, a record power-to-weight ratio according to Siemens

Dr. Frank Anton with 50 kilogram, 250 kW motor, a record power-to-weight ratio according to Siemens.  Dr Anton will speak at EAS IX

Siemens claims a world record of five kilowatts per kilogram, although Roman Susnik, with his Emrax motors pulling close to 10 kilowatts per kilogram, might contest that, and LaunchPoint is working toward eclipsing that mark.  To be fair, it’s certainly a giant boost over the power-to-weight ratio of most industrial-type electric motors, which Siemens also produces in large numbers. The company, according to its press release, intends to start flight testing the new motor before the end of this year, and hopes to increase output even more.

In 2013, Siemens partnered with Airbus and Diamond Aircraft to work on new electric propulsion system, conducting flight tests of a 60 kW series hybrid-electric drive on a DA36 E-Star 2 motor glider.  In series-hybrid form, the new motor could power electric aircraft up to two tons for the first time.   In hybrid or battery-only form, Siemens motors enable lighter airframes or greater payloads, especially important as electric aircraft attempt to gain parity with their fossil-fuel cousins.

Siemens 260 kW motor on test rig

Siemens 260 kW motor on test rig

The motor’s high torque and power output at 2,500 or few revolution per minute enable direct drive to a big propeller, further saving weight.  Dr. Anton thinks this points toward a future in which, “the use of hybrid-electric drives in regional airliners with 50 to 100 passengers is a real medium-term possibility.”

Dr. Frank Anton will headline the Motors/Controller/Propulsion/Quietude theme dinner, Friday, May 1 at the ninth annual Electric Aircraft Symposium.

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Green Car Congress reports that, “Stanford researchers led by Professor Yi Cui have used ceramic nanowire fillers to enhance the ionic conductivity of polymer-based solid electrolyte by three orders of magnitude. The ceramic-nanowire filled composite polymer electrolyte also shows an enlarged electrochemical stability window.”

With solid-state batteries coming to the fore through efforts by Ann Marie Sastry at Sakti 3 and Qichao Hu at Solid Energy Systems, an improved solid electrolyte would seem to offer greater battery safety and stability “when compared with conventional liquid electrolytes.
Solid-state electrolyte provides safety and stability with much higher conductivity

Solid-state electrolyte provides safety and stability with much higher conductivity.   Note much higher energy conductivity for PAN-lithium Chlorate with titanium oxide nanowires, apparently varying little with temperature changes.  Diagrams on right show difference between unconnected nanoparticles and those connected with nanowires

The abstract for the Stanford researchers’ paper in the journal ACS Nano Letters explains that “Currently, the low mobility of lithium ions in solid electrolytes limits their practical application. The ongoing research over the past few decades on dispersing of ceramic nanoparticles into polymer matrix has been proved effective to enhance ionic conductivity although it is challenging to form the efficiency networks of ionic conduction with nanoparticles. In this work, we first report that ceramic nanowire fillers can facilitate formation of such ionic conduction networks in polymer-based solid electrolyte to enhance its ionic conductivity by three orders of magnitude. Polyacrylonitrile (PAN)-LiClO4 (lithium perchlorate) incorporated with 15 wt % Li0.33La0.557TiO3 (lithium oxide, lanthanium – a rare earth – oxide, titanium oxide) nanowire composite electrolyte exhibits an unprecedented ionic conductivity of 2.4 × 10–4 S cm–1 at room temperature, which is attributed to the fast ion transport on the surfaces of ceramic nanowires acting as conductive network in the polymer matrix. In addition, the ceramic-nanowire filled composite polymer electrolyte shows an enlarged electrochemical stability window in comparison to the one without fillers. The discovery in the present work paves the way for the design of solid ion electrolytes with superior performance.”

Green Car Congress reports, “They investigated the ionic conductivities of their solid electrolytes via AC impedance spectroscopy measurements with two stainless steel blocking electrodes.

“The composite electrolyte with 15 wt % LLTO nanowires displayed the highest conductivity of 2.4 × 10−4 S cm−1 at room temperature—about three orders of magnitude higher than that of PAN-LiClO4 without fillers (2.1 × 10−7 S cm−1).”

This jump in conductivity, coupled with materials already used in existing solid-state batteries, might lead to lighter, more energy dense cells that could be applicable in electric vehicles – in particular, light aircraft.

The Nano Letters paper concludes, “Our work opens the door for novel developments of one-dimensional Li+-conducting ceramic materials in solid electrolytes for lithium-ion batteries.”

Dr. Cui is a constant presence in the blog, having created batteries literally on paper, formed the experimental basis for technology that became Amprius, a Sunnyvale, California-based manufacturer of “high energy and high capacity lithium batteries,” and now working on solid-state batteries.  He will speak at the ninth annual Electric Airplane Symposium in Santa Rosa, California on May 2, 2015.

His talk, “Materials Design for Battery Breakthroughs: from Fundamental Science to Commercialization,” promises a great overview of his teams’ work.  He gives a preview in this synopsis.  “In the past two decades rechargeable batteries have been a great success in powering consumer electronics. There is a recent strong interest in applying rechargeable batteries to electrification of transportation, which present new challenges and opportunities for batteries including energy density, cost, safety and cycle life. There I present our breakthrough battery technology enabled by novel materials design. High-energy batteries examples include silicon and lithium metal anodes and sulfur cathodes, which have 10x charge storage capacity of current technology. We also designed smart separators which could enhance the battery safety significantly. The commercialization pathway of some of these breakthroughs will also be presented.”

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 Since last August at AirVenture 2014, Elytron Aircraft, LLC has made great progress.  The aircraft on display at Oshkosh last year was promising, but about half finished.  The completed two-seat, proof-of-concept (POC) airframe shown March 3rd through 5th this year at the HAI Heli Expo in Orlando, Florida seems ready to go and remarkably light at its 1,100 pound design goal. Elytron lists the following component advances for the last seven months, including completion of:

  •  All carbon fiber work for the fuselage as well as the joined wings.
  • The patented center wing, now fitted with its tilting mechanism and vertical flight control surfaces.
  • All systems required for ground movement (taxiing).
  • Installation and run-up of the turbocharged 450 sHP engine.
  • Installation of avionics including ADS-B in/out.
Elytron's 2S proof-of-concept demonstrator at the March HAI Heli Expo

Elytron’s 2S proof-of-concept demonstrator at the March HAI Heli Expo

Its maiden flight is scheduled for mid-2015, with a full transition in and out of VTOL mode by the end of the year.

Not content to show just a two-seat technology demonstrator, Elytron revealed its new design for a 4-seat executive transport and air taxi aircraft at the Heli Expo. This design is based on a 1,075 sHP turboprop engine and, according to Elytron, will be capable of cruise speeds up to 316 mph.

The 4S will provide fast transport for four in cabin comfort

The 4S will provide VTOL capabilities, fast transport for four in cabin comfort

Elytron’s 10-seat design is configured to carry personnel to offshore oil and gas deep water platforms at cruise speeds of 414 mph, more than twice as efficient as existing helicopter-based solutions. With a dual turboshaft configuration for a total of 4,000 sHP and a range of 1,295 nautical miles, this would provide rapid transit and vertical takeoff and landings. Oliver Garrow, co-founder and Chief Technology Officer for Elytron, reports that Elytron is evaluating the feasibility of using existing airframes to build initial prototypes for the 10-seat aircraft as a means of accelerating development, and extending its design concept to include unmanned platforms (drones).

10S, the largest model so far in conceptual design, would cruise at 414 mph

10S, the largest model so far in conceptual design, would carry 10 at 414 mph

Elytron was founded in 2013 with Gregory Bruell, programmer and executive, as CEO and Co-Founder along with Oliver to provide a faster, safer, and a longer-range alternative to helicopters for the oil and gas, emergency medical services, and air taxi markets. Oliver worked on the design concept over a 10-year R&D period during which he conducted experiments were conducted with 1/4th scale convertiplanes models on Moffett Field.  Testing included full-size airframe modeling, extended flight, and computational fluid dynamics (CFD) simulations. The popular Verticopter flying-wing design with in-wing propulsion was the most successful of these prototypes but still had aerodynamic limitations. In 2012, Oliver created the new and optimized wing configuration to address all of the earlier design limitations.

As explained by Oliver, “The Elytron aircraft architecture combines three sets of wings: one pair of rotary wings called ‘proprotors,’ mounted along a single tilt-wing in a central position, and two joined pairs of fixed wings. The plane has superior glide ratios and low stall speeds because of its low wing-loading design, and also displays excellent Short Take-off and Landing (STOL) capabilities.”

Elytron aircraft are claimed to be capable of achieving airspeeds two to three times those of equivalently powered helicopters. The airframe has also been optimized for low drag at the higher airspeeds due to its unique distribution across 3 sets of wings. Stall performance is claimed to be very safe as it borrows from airframes using a front wing with canard-type stall response. Fixed wing planes are also far more fuel efficient than rotary wing aircraft, reducing operational costs and increasing range. The combination of the speed of a fixed wing plane and the vertical take-off of a helicopter will allow for applications such as air taxi from city-center to city-center.

The Elytron mechanism for controlling the plane during vertical flight has far fewer parts than helicopter swash plates. Elytron’s design has no complex hub but instead distributes the parts across the tilt-wing, making them lighter and easier to inspect and maintain, according to Oliver. All of the tilt-wing actuators have redundant control. In the case of engine failure, the airframe’s superior glide ratio will eliminate the need for autorotation, which is a requirement in any helicopter.

The anticipated benefits of the unique configuration and its promised performance are essential to the success of the new company.  Best wishes to Oliver and Greg in this endeavor.

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After a 13-hour flight from Varanasi, India, to Mandalay (VYMD) in the Republic of the Union of Myanmar, Bertrand Piccard and Andre’ Borschberg have now had more press conferences than landings, giving a clue as to the real mission of Solar Impulse 2.

Andre' Borschber gnad Bertrand Piccard are surrounded by reporters and photographers after Piccard landed HB-SIB in Mandalay, Myanmar.  Photo Solar Impulse | Revillard

Andre’ Borschber gnad Bertrand Piccard are surrounded by reporters and photographers after Piccard landed HB-SIB in Mandalay, Myanmar. Photo Solar Impulse | Revillard

Flights thus far have been fairly uneventful, which is a plus in any pilot’s logbook.  The two pilots seem to be busier when they touch down, first finding themselves surrounded by media, then attending a series of events in which they talk about their visions for a better, cleaner future.  In Myanmar, that includes sharing the benefits of the high technology of Solar Impulse’s solar collectors with a country that lacks electricity in 70 percent of its population.   Myanmar shows up as a dark spot in night-time satellite views of southern Asia.

The Solar Impulse team works with Pact, a non-profit organization dedicated to improving the lot of the “poor and marginalized” by helping them “discover and build their own solutions and take ownership over their future.”

At one meeting, in which the pair endorsed Pact’s mission in Myanmar, the pilots and Pact’s Myanmar country director, Richard Harrison, presented solar power packages to women from Tada Oo Township, Mandalay Region.  This is part of a larger project with Solar Impulse’s partner ABB that will establish solar charging stations in remote villages in the Tada Oo township in central Myanmar.  ABB, a developer of control and power systems, also provides systems for regulating energy use on HB-SIB.

ABB notes, “Power from these stations will be sold to communities, bringing not merely electricity but economic self-sufficiency, entrepreneurship and equality – and safety.

“’I am excited,’ said U Thein Hla, a 70-year-old resident from Wun Pa Tae Village. ‘Now, we don’t need to worry about fire hazard associated with the use of candle light.’”  Many such locals earn less than $1.00 a day harvesting foods such as betel nuts.  Electrification could lead to expanded job opportunities, greater productivity from the ability to work and study at night, and since women are running the projects, both literal and figurative empowerment for their gender.

Bertrand Piccard and Andre' Borschberg receive gift from Myanmar president U Sein Thein

Bertrand Piccard and Andre’ Borschberg receive gift from Myanmar president U Sein Thein

ABB reports that Bertrand Piccard was enthusiastic to be part of this.  “I am very touched and excited about this project.  It demonstrates that ABB and Pact make our vision a reality.”

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Getting a GloW On

Great Britain has recently allowed very light aircraft to fly under SSDR (Single-Seat DeRegulated) rules, which permit single-seat aircraft with an MTOM (maximum take-off mass) of not more than 300 kilograms (660 pounds) and a landing speed of not more than 35 knots (40.27 mph or 64.82 kilometers per hour).  With weights and speeds a bit higher than those allowed for American ultralights, these would be desirable as a way to expand the number of aircraft flying under ultralight rules.  How a machine such as the ProAirsport’s GloW will be regulated in America remains to be seen.

ProAirsport GloW includes jet turbine for climbing, dual electrically-driven wheels for acceleration

ProAirsport GloW includes jet turbine for climbing, dual electrically-driven wheels for acceleration

Formed in 2014, ProAirsport will built light aircraft around the new British rules while adopting ASTM F2564, Standard Specification for Design and Performance of a Light Sport Glider, as a way to meet light sport standards worldwide – including in America.  You can see the abstract here, but the full set of standards costs $49.00 plus shipping.

The actual machine, shown here in computer renderings, will meet SSDR limits, and be powered by a Dutch AMT Titan microturbine that generates 40 kilograms (88 pounds) of thrust.  The eight-pound jet sits in a fixed position, needing only to be flipped on and started to produce power.

13.5-meter wings allow light weight, single-person rigging of aircraft

13.5-meter wings allow light weight, single-person rigging of aircraft

Because jets have sometimes very slow acceleration when the throttle is advanced, GloW’s designers have added a pair of motorized main wheels to help overcome that lack.  Electric motors have great torque for their size, even at zero speed.  This combination of retractable“helper wheels” with a small jet to loft the sailplane to altitude seems to provide one solution to self-launching.

The little engine is thirsty, sucking down 36 ounces of fuel per minute.  That means takeoff and climb to 2,500 feet will consume about 6.5 liters, or about 1.717 U. S. gallons of kerosene, diesel (including agricultural, recycled and bio-diesel types), jet fuel, or other approved form of go juice.  A planned 34 liters on board (subject to change) would enable five take-offs and climbs to soarable heights.  In flight, a cruising throttle would enable flight on 20-percent power, sipping one-half liter per minute, good for close to an hour of autonomous flight.  (Editor’s Note: Original number for U. S. gallons of fuel was too low and was corrected by Howard Handelman.  This little engine is definitely thirsty.)

The 300 kilogram MTOM has allowed GloW’s designers to use less expensive, heavier fiberglass construction, rather than the carbon fiber preferred to help keep U. S. ultralights within the 254-pound, FAR Part 103 limits.

Even though the jet can spool from minimum to full RPMs in four seconds and down from full throttle to idle in three seconds, acceleration of the 660-pound total weight is slow enough to require the use of a seven-horspower (peak output) wheel motor to kick start the takeoff.

According to ProAirsport, “Our high-torque brushless motor is a standard unit customized for our use profile and with a purpose built controller from the motor manufacturer for true technical compatibility… Electrically driven wheels also provide for taxi capability before take-off and after landing – without running the turbine.”  The CAFE Foundation has promoted use of wheel motors to enhance acceleration in its proposed Sky Taxis.

Once airborne with the turbine shut down, time and distance become dependent on the pilot.  The 13.5-meter (44.28-foot) wings are designed for a rate of sink of only 120 feet per minute and a glide ratio of 36.

Roger Hurley, the company’s head, uses the slogan, “Prepare to fly more, fly for less,” and promises a surprisingly low price for the new machine.  With two prototypes under construction, one to meet British SSDR regulations and one that will suit U. S. Light Sport rules, we can hope that GloW will come with positive sticker shock and confirmation of its promised performance.

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Buy Silkworm Futures Now

We tend to think of batteries as being inanimate objects, even though they expand, contract and flex their electric muscles within their cylindrical or pouch forms as they charge and discharge.  This type of internal wiggling helps reduce and finally destroy the battery’s ability to make our remotes change channels or keep our airplanes flying.

Researchers at the Beijing Institute of Technology have found a way to use the product of much internal and external wiggling, natural silk that is “biomass-derived” and processed to form carbon-based nanosheets that might be used in lithium-ion batteries and other energy storage devices.

The American Chemical Society reports that Chuanbao Cao and his researchers worked with the idea that carbon is a key component in commercial Li-ion energy storage devices including batteries and supercapacitors.  They wanted to find a natural and sustainable alternative to graphite, which has limited specific energy and eventually granulates into a fine powder, causing the battery to fail.

Simultaneous activation and graphitization of silk precursor

Simultaneous activation and graphitization of silk precursor

Cao and colleagues performed “simultaneous activation and graphitization of the silk,” making the processed silk into “hierarchical porous nitrogen-doped carbon (HPNC) nanosheets (NS).”

They dissolved the silk in iron chloride (FeCL3) and zinc chloride (ZnCl2), which acted “as effective activation-graphitization agents that can introduce a porous structure with plentiful micro- and mesopores for a high surface area.”

These sheets have a high specific surface area, covering an SBET of 2,494 square meters (26,845 square feet) per gram, or about 90-percent of a football field.  “SBET,” stands for surface area as measured by a technique developed in 1938 by Stephen Brunauer, P.H. Emmet and Edward Teller to measure the specific surface of finely divided and porous solids.

The sheets self-assemble in hydrophilic (water loving) and hydrophobic (water hating) blocks in an aqueous system.  This forms a series of different sheets which, because of their uneven surfaces, don’t quite come together and provide spaces between the sheets and through the many pores in their surfaces, for electrolyte and ions to flow.

As explained in Green Car Congress, “The resulting HPNC-NSs have a thickness in the range of 15 to 30 nm; the folds of the nanosheets limit them from stacking together. The layer-to-layer distance is 0.40 nm. The nanosheet architecture not only offers minimum diffusive resistance to mass transport on a large electrode/electrolytes interface for charge-transfer reaction but also provides easy ion transport by shortening the diffusion pathways.”

test

Electrochemical performance of HPNC-NS as a Li-ion battery anode.  (a) charge-discharge curves at 0.1 Amp per gram: (b) CVs of initial four cycles at a scan rate of 0.1 millivolt per second; (c) capacity over cyclclingat different rates; and (d) cyclability at 3,270 mA/g.  Credit: ACS, Hou et al.

The layers and pores have demonstrated excellent energy storage capacity and longevity, with the team reporting, “A reversible lithium storage capacity of 1865 mAh/g—the highest for N-doped carbon anode materials to the best of the researchers’ knowledge. Used as a supercapacitor electrode in ionic liquid electrolytes, the HPNC-NS exhibit a capacitance of 242 F/g and energy density of 102 Wh/kg (48 Wh/L), with high cycling life stability (9% loss after 10,000 cycles).”

Since the new materials seem to function well in supercapacitors and as battery anodes, and can be scaled for industrial production, there would seem to be a bright future for silkworms and their products.  Will competition for silk cause clothing prices to rise, much like ethanol caused spikes in corn prices?

A paper, “Hierarchical Porous Nitrogen-Doped Carbon Nanosheets Derived from Silk for Ultrahigh-Capacity Battery Anodes and Supercapacitors,”  describing the research was published in the journal ACS Nano.

The abstract gives an overview of the research and its results.

“Hierarchical porous nitrogen-doped carbon (HPNC) nanosheets (NS) have been prepared viasimultaneous activation and graphitization of biomass-derived natural silk. The as-obtained HPNC-NS show favorable features for electrochemical energy storage such as high specific surface area (SBET: 2494 m2/g), high volume of hierarchical pores (2.28 cm3/g), nanosheet structures, rich N-doping (4.7%), and defects. With respect to the multiple synergistic effects of these features, a lithium-ion battery anode and a two-electrode-based supercapacitor have been prepared. A reversible lithium storage capacity of 1865 mA h/g has been reported, which is the highest for N-doped carbon anode materials to the best of our knowledge. The HPNC-NS supercapacitor’s electrode in ionic liquid electrolytes exhibit a capacitance of 242 F/g and energy density of 102 W h/kg (48 W h/L), with high cycling life stability (9% loss after 10 000 cycles). Thus, a high-performance Li-ion battery and supercapacitors were successfully assembled for the same electrode material, which was obtained through a one-step and facile large-scale synthesis route. It is promising for next-generation hybrid energy storage and renewable delivery devices.”

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Solar Impulse 2, HB-SIB, is parked on the tarmac at Ahmedabad (Sardar Vallabhbhai Patel International Airport, AMD/VAAH), fresh from its record-making flight from Oman.  Crew members pore over its mechanical and electrical components in preparation for its next flight to Varanasi, also in the Republic of India.  In the meantime pilots Andre’ Borschberg and Bertrand Piccard share the message of their Future Is Clean organization and prepare themselves physically and spiritually for the voyage ahead.

Apropos of their stopovers in India, Borschberg and Piccard have practiced Yoga as part of the physical discipline necessary for the grueling long-distance flights to come, and Borschberg is seen in one photo using a modern version of a traditional healing practice called Shirodhara, which involves pouring a steady stream of water or other liquids appropriate for the therapy.  The term comes from the Sanskrit words shiro (head) and dhara (flow), according to Wikipedia.

While SI2 receives a thorough health check in background, Andre Borschberg receives benefits of modern version of shirodhara, a traditional cleansing therapy

While SI2 receives a thorough health check in background, Andre Borschberg receives benefits of modern version of shirodhara, a traditional cleansing therapy

This cleansing of the body and spirit coincides with the greater mission of the flight, to cleanse the world of effects of global pollution.

According to Solar Impulse, “The platform http://www.FutureIsClean.org, was designed with the support of our web partner, Google, and aims to mobilize individuals, organizations, celebrities and politicians to confront the Conference on Climate Change of the United Nations (COP21), which will define the new Kyoto protocol in December 2015 in Paris. The goal is to establish the largest petition ever created to convince governments to implement technological solutions that are necessary. Every site visitor is asked to add their voice to the message “I want concrete solutions for a clean future” and share amongst their networks.”

Typical crowd of school children in Ahmedabad show drawing power of giant solar aircraft

Typical crowd of school children in Ahmedabad show drawing power of giant solar aircraft

To gain support for this message and educate those who come to see the giant solar-powered craft, the team holds press conferences and meets with dignitaries, students and technological leaders in the countries they visit.  They also stage on-line Google Hangouts throughout the trip.

As they told reporters before beginning the first leg of the flight, “Only a significant support will push governments to replace old polluting technologies with clean and efficient technologies. This is what we want to create throughout our solar powered Round-The-World Flight. If there are technological solutions to fly a plane day and night without fuel, imagine the potential of these technologies in our daily lives, to achieve energy savings and reduce CO2 emissions. This would help create jobs, develop new industrial markets while also protecting the environment”.

With backing from supporters such as HRH Prince Albert of Monaco and Richard Branson, Masdar, Irena (the International Renewable Energy Agency), New 7 Wonders and Green Cross International, the Solar Impulse web site follows and documents the flight itself, while Future Is Clean discusses the environmental and political implications of the venture.

The Si2 Round-The-World flight has made its first stops in Abu Dhabi, Muscat, Oman; and Ahmedabad and Varanasi, India.  It will continue to Mandalay, Myanmar; and Chongqing and Nanjing, China. After crossing the Pacific Ocean via Hawaii, Si2 will fly across the U.S.A. stopping in Phoenix, the Midwest, and New York City at JFK. After crossing the Atlantic Ocean, the final legs include a stop-over in Southern Europe or North Africa before completing the Round-The-World flight at its final destination in Abu Dhabi.

If the excited crowds visiting the airplane in India are any indication, the flight could have a profound effect on public perception of what is possible with clean energy.

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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.

This schematic diagram depicts the concept for a new electrode design for lithium-ion batteries that has been shown to potentially reduce the charging time from hours to minutes by replacing the conventional graphite electrode with a network of tin-oxide nanoparticles. (Purdue University image/Vinodkumar Etacheri)

This schematic diagram depicts the concept for a new electrode design for lithium-ion batteries that has been shown to potentially reduce the charging time from hours to minutes by replacing the conventional graphite electrode with a network of tin-oxide nanoparticles. (Purdue University image/Vinodkumar Etacheri)

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 quite capacitor-quick, but speedier than normal slow charging, the anode can be charged in 30 minutes as opposed to a slow charge of 10 hours for the graphite anode.  The experimental tin-oxide anode has a capacity of 430 mA h/g.  Undoubtedly, this capacity will be restricted by electrolytes or other components of lesser capacity. The trick still seems to be to develop a wholistic battery approach, making an integrated system that optimizes the performance of all components.

The anode’s “ordered network” of tin oxide nanoparticles has commercial promise, being “synethsized by adding the tin alkoxide precursor into boiling water followed by heat treatment,” according to Pol.

Pol explains, “We are not using any sophisticated chemistry here.  This is very straightforward rapid ‘cooking’ of a metal-organic precursor in boiling water. The precursor compound is a solid tin alkoxide—a material analogous to cost-efficient and broadly available titanium alkoxides. It will certainly become fully affordable in the perspective of broad-scale applications.”

Heating the tin oxide nanoparticles at 400°C causes them to self-assemble into a network containing pores that allow the material to expand and contract, or breathe, during the charge-discharge battery cycle.

While other electrode researchers have tried constraining their materials to prevent expansion and contraction, Vinodkumar Etacheri explains that, “These spaces are very important for this architecture,  Without the proper pore size, and interconnection between individual tin oxide nanoparticles, the battery fails.”

The group’s finding are published in the November issue of the journal Advanced Energy Materials.

According to the Purdue press release, the research paper was authored by Etacheri; Swedish University of Agricultural Sciences researchers Gulaim A. Seisenbaeva, Geoffrey Daniel and Vadim G. Kessler; James Caruthers, Purdue’s Gerald and Sarah Skidmore Professor of Chemical Engineering; Jeàn-Marie Nedelec, a researcher from Clermont Université in France; and Pol.

Electron microscopy studies were performed at the Birck Nanotechnology Center in Purdue’s Discovery Park. Future research will include work to test the battery’s ability to operate over many charge-discharge cycles in fully functioning batteries.

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Solar Impulse on First Leg of Epic Tour

Solar Impulse 2, under the control of André Borschberg, took off at 7:12 a. m. (03:12 UTC) Abu Dhabi time, on the first leg of its around-the-world voyage.  The roughly 400 kilometers (215 nautical miles) between Abu Dhabi and Muscat, Oman – the airplane’s first stop – takes less than an hour by airliner and around five hours (according to Google Maps) by Maybach or lesser motor vehicle.  It took André nine hours, one minute for this leg, traveling at ultralight speeds.  His landing was tweeted as looking like a UFO descending, LED landing lights ablaze and advancing slowly overhead. 

In the control room, Bertrand Piccard and His Serene Highness Prince Albert II of Monaco followed the flight with advice and encouragement.  His Highness helps promote aviation ventures which show promise for cleaning the atmosphere, including record attempts by Jean-Luc Soullier in his electric aircraft.

(NOTE: You might have to scroll the video to the beginning to see all the action, but the landing itself begins at about the 37:00 mark.)

It’s a nice baby step, a kind of final shakedown cruise before the second leg takes it over the Gulf of Oman and the northern part of the Arabian Sea to Ahmedabad, India.  That flight will be about 1,435 kilometers (892 miles) as traversed by commercial airliner, and although not delineated in Google Maps, well over 60 hours by car, taking a big loop around the United Arab Emirates, Qatar, Kuwait, Bahrain, Iran, and Pakistan.  Many border crossings would doubtless slow progress.

The next leg will be the longest over-water trip thus far in either Solar Impulses’ careers.  Again, it’s a good trial of machine and pilot for what will be epic flights over the world’s great oceans, taking five days and nights for each major water crossing.

With the safe landing of Andre’ Borschberg in Oman, a ground crew immediately started preparing HB-SIB for its first long over water flight, which will make a hoped-for uneventful passage to India.

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