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Pipe: Advanced tech

Toyota Motor continues rollout of Otto-Atkinson engines with 2016 Lexus IS 200t

Fri, 2015-07-24 12:57

Lexus is entering the 2016 model year with a three model strategy for its IS sport sedan: IS 200t, IS 300 AWD, and IS 350. The former IS 250 and IS 250 AWD are discontinued. The new IS 200t, available as RWD only, features a 2.0-liter twin-scroll turbocharged inline four-cylinder engine with intercooler paired to an eight-speed automatic transmission. Variable Valve Timing intelligent – Wide (VVTi-W) allows the engine to switch between the Otto and Atkinson cycles. (Earlier post.)

Atkinson cycle mode is used in extremely low load conditions, when the intake valve remains open for a fraction of time, after the compression stroke has set in, allowing part of the gas charge to be pushed back into the intake. As a result, the effective compression stroke is shortened. Pumping losses are reduced, since the pressure on the piston is lower, and also the throttle valve can be opened wider.

The engine cranks out 241 hp (180 kW) and 258 lb-ft (350 N·m) of torque at 1,650-4,400 rpm. Lexus developed the turbocharged engine in house, first integrated it into the NX luxury utility hybrid for 2015 model year, and modified it for IS 200t.

The IS 200t features a combination of water-cooled cylinder head, integrated exhaust manifold and twin scroll turbocharger for fast throttle response, performance and high torque at low engine revs.

The D-4ST direct injection system combines a high pressure fuel system for injection directly in to the cylinders with a low pressure system for injection into the ports. Injection is split between the direct and port injectors according to the engine load to help fuel economy.

Georgia Tech ultra-thin hollow nanocages could significantly reduce platinum use in fuel cell electrodes

Fri, 2015-07-24 12:39

A team led by researchers at Georgia Tech has developed a new fabrication technique to produce platinum-based hollow nanocages with ultra-thin walls that could significantly reduce the amount of the costly metal needed to provide catalytic activity.

Use of these nanocage structures in fuel cell electrodes could increase the utilization efficiency of the platinum electrocatalyst by a factor of as much as seven, potentially changing the economic viability of the fuel cells. The work also involved researchers at the University of Wisconsin-Madison; Oak Ridge National Laboratory; Arizona State University; and Xiamen University in China. The process is described in a paper in the journal Science.


A) Mass and (B) specific activities of the catalysts at 0.9 VRHE. (C) Mass activities (at 0.9 VRHE) and (D) specific ECSAs of the catalysts before and after accelerated durability test. The color scheme applies to all panels. Source: Zhang et al. Lei Zhang et al. Science 2015; 349:412-416 Click to enlarge.

In catalytic applications, only the surface layers of platinum contribute to the chemical reaction, leading researchers to develop new structures designed to maximize the amount of platinum exposed to reactants.

One strategy to increase the utilization efficiency (UE) of platinum group metals (PGMs) is to increase the proportion of atoms exposed on the surface (the dispersion) by reducing particle size. For example, the UE of platinum (Pt) atoms can be increased from 9.5 to 26% by reducing the edge length of a Pt cube from 11.7 to 3.9 nm. Despite the extensive use of this strategy, it has been difficult to optimize the specific activity of such small nanocrystals (NCs) by engineering their surface structure through facet-controlled synthesis. Such NCs also tend to sinter (form larger particles), detach from the support, or both during operation.

An alternative strategy is to use nanoframes—open nanostructures comprising multiple ridges as thin as a few nanometers. Each ridge of a nanoframe can be considered as a linear aggregate of NCs. Essentially, all the PGMs can be prepared as nanoframes by using methods that involve the selective removal of a sacrificial component: for example, the more reactive metal in alloyed NCs or the NC serving as a template for the site-selected deposition of the PGM. … this method still faces challenges in selecting the exposed crystal facet with which to control their catalytic activity and selectivity.

A different strategy for increasing the UE of a PGM is to assemble the metal atoms into nanosheets. For such a system consisting of four atomic layers, the UE could in principle reach 50%, but the use of PGM nanosheets as catalysts encounters several drawbacks: (i) the top and bottom surfaces of a sheet must be capped by ligands; (ii) the metal atoms can only assume a hexagonal lattice, corresponding to one type of facet only; and (iii) it is challenging to deposit and expose individual nanosheets on a catalytic support. An alternative to this strategy is to deposit the PGM conformally as sub-nanometer-thick shells of only a few atomic layers on the surfaces of NC templates made of another metal.—Zhang et al.

The Georgia Tech-led team took that last approach. Their technique uses a solution-based method to grow platinum layers on palladium nanocrystal templates. The palladium is then etched away to leave behind nanocages approximately 20 nanometers in diameter, with between three and six atom-thin layers of platinum. When conducted appropriately, the researchers said, the facets presented on the surface of the template can be well preserved during the Pt coating and Pd etching processes so as to engineer the activity and/or selectivity of the catalyst.

In the work described in the paper, the researchers demonstrated the concept by coating the surfaces of Pd nanoscale cubes and octahedra with four atomic layers of Pt, followed by selective removal of the Pd templates. (The shape, cubic or octahedral, controls the surface structure, thus engineering the catalytic activity.)

We can get the catalytic activity we need by using only a small fraction of the platinum that had been required before. We have made hollow nanocages of platinum with walls as thin as a few atomic layers because we don’t want to waste any material in the bulk that does not contribute to the catalytic activity.

We can control the process so well that we have layer-by-layer deposition, creating one layer, two layers or three layers of platinum. We can also control the arrangement of atoms on the surface so their catalytic activity can be engineered to fit different types of reactions.—Younan Xia, a professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University

Hollow platinum structures have been made before, but not with walls this thin, Xia said. Earlier work produced shells with wall thicknesses of approximately five nanometers. The new process can produce shell walls less than one nanometer thick. With both the inner layer and outer layer of the porous nanocages contributing to the catalytic activity, the new structures can use up to two-thirds of the platinum atoms in an ultra-thin three-layer shell. Some palladium remains mixed with the platinum in the structures.

Durability testing showed that Pt octahedral nanocages delivered the best performance, with the ORR mass activity only reduced by 36% after 10,000 cycles, still showing 3.4-fold enhancement relative to the pristine Pt/C. The ECSAs of the cubic and octahedral nanocages only dropped by 13 and 6% after 5000 cycles and by 32 and 23% after 10,000 cycles, respectively.

Contributing to the experimental work done at Georgia Tech, researchers at Arizona State University and Oak Ridge National Laboratory used their specialized microscopy facilities to map the nanocage structures. Researchers at the University of Wisconsin-Madison modeled the system to help understand etching of palladium from the core while preserving the platinum shell.

Researchers have explored alternatives to platinum, but none of the alternatives so far has provided the equivalent amount of catalytic activity in such a small mass, Xia noted.

Other authors in the paper include Professor Manos Mavrikakis and researchers Luke Roling and Jeffrey Herron from the University of Wisconsin-Madison, Miaofang Chi from Oak Ridge National Laboratory, Professor Jingyue Liu from Arizona State University, Professor Zhaoxiong Xie from Xiamen University, and Lei Zhang, Xue Wang, Sang-Il Choi, Madeleine Vara and Jinho Park, from Georgia Tech.

Resources

  • Lei Zhang, Luke T. Roling, Xue Wang, Madeline Vara, Miaofang Chi, Jingyue Liu, Sang-Il Choi, Jinho Park, Jeffrey A. Herron, Zhaoxiong Xie, Manos Mavrikakis, and Younan Xia (2015) “Platinum-based nanocages with subnanometer-thick walls and well-defined, controllable facets” Science 349 (6246), 412-416 doi: 10.1126/science.aab0801

EV World publisher seeking to Kickstart e-bike project; EcoForce bamboo/aluminum bike with Bike+ All-in-One hub as incentive

Fri, 2015-07-24 11:53

Bill Moore, the publisher of EV World and longtime electric bike enthusiast, has spunoff a company, QuikByke, that will rent top-quality electric bicycles in tourist markets on a seasonal cycle: winter in the tropics, summer in the north. The e-bikes are housed in mobile solar-powered rental shops based on 20 ft shipping containers (called Q•pods), each with 15 bikes. Moore is seeking $275,000 in crowdsourced funding by 14 August to build Q•pod #1.


As an incentive for supporters, QuikByke is offering the K15, a Greenstar Bikes Ecoforce 1 bamboo and recycled aluminum e-bike powered by the BIKE+ All-In-One hub motor by Zehus s.r.l. of Milan, Italy. The BIKE+ rear bike hub contains brushless motor, 160 Wh battery, electronics and sensors, all within 180 mm diameter and 120 mm width. With a weight of just 3 kg (6.6 lbs), BIKE+ All-In-One has the highest energy/weight ratio on the market.


At just over 31 pounds (less than 15 kg), the K15 (hence the name), including motor, is among the lightest electric bicycles. QuikByke is offering a signed, limited pre-production run of 150 of the K15 bikes for an investment of US $1,975.


J.D. Power: growing usage of safety technologies in new vehicles contributes to increasing vehicle appeal

Fri, 2015-07-24 11:22

The safety-related technologies with which manufacturers are increasingly equipping their new vehicles are making those vehicles more appealing to their owners, according to the J.D. Power 2015 US Automotive Performance, Execution and Layout (APEAL) Study.

The APEAL Study, now in its 20th year, examines how gratifying a new vehicle is to own and drive. Owners evaluate their vehicle across 77 attributes, which combine into an overall APEAL Index score that is measured on a 1,000-point scale. The overall APEAL score has increased by 4 points year over year to 798 in 2015. The study finds that some safety features can contribute to a significant boost in APEAL scores. For example, the overall score among owners of vehicles with blind-spot monitoring and warning systems is 38 points higher than among those without them.


Click to enlarge.

The study finds that 36% of owners have blind-spot monitoring and warning systems in their vehicle (up 7 percentage points from 2014); 21% have lane-departure warning systems (up 5 percentage points); 46% have park assist/backup warning (up 4 percentage points); and 25% have collision avoidance/alert systems (up 4 percentage points).

Furthermore, 69% of owners who have blind-spot warning systems and 62% with park assist systems indicate they use them every time they drive. Only 15% of owners say they have had previous experience with blind-spot warning systems, and only 39% say their dealer explained the feature to them upon vehicle delivery.

Unlike other technologies, such as voice recognition, that can be challenging to operate, most safety features provide information in a more intuitive way, giving owners a greater sense of security. Not only are models increasingly offering systems that improve safety and visibility, but owners are also using them on a regular basis. This can go a long way toward generating positive feelings about their vehicle overall.—Renee Stephens, vice president of US automotive quality at J.D. Power

According to the J.D. Power 2015 US Tech Choice Study, consumers are willing to spend substantially more on vehicles that include certain safety features. For example, respondents in that study indicate a willingness to pay a market price of $750, on average, for blind-spot detection and prevention systems.

APEAL gap narrows between premium and non-premium brands. While premium brands historically perform significantly higher than non-premium brands in the APEAL Index, study findings show that the gap between the two in 2015 is the smallest it’s been in the past 10 years, narrowing by 16% since 2006. The average APEAL Index score in the non-premium segment (790) has improved by 5 points from 2014, while the average score in the premium segment (841) has improved by only 1 point.

Over the past several years, we have seen non-premium brands increasingly offer the types of in-vehicle technologies that used to be available only to premium buyers. The positive impact these technologies have on owners is more pronounced among non-premium owners. In fact, owners of non-premium vehicles that include the latest technology register higher APEAL scores by 50 points, compared with just a 29-point increase among owners of premium vehicles with the same technologies.—Renee Stephens

Porsche ranks highest in APEAL for an 11th consecutive year, with a score of 874 index points. Porsche is followed in the rankings by Jaguar (855), BMW (854), Mercedes-Benz (853) and Audi (852). MINI is the highest-ranking non-premium brand in the study with a score of 825.

The following brands receive multiple model-level APEAL awards:

  • Chevrolet (three): Colorado, Corvette and Sonic
  • Ford (three): C-Max, Expedition and F-150
  • Porsche (three): Cayenne, Cayman and Macan
  • Audi (two): A3 and Q3
  • BMW (two): 4 Series and 6 Series
  • Dodge (two): Challenger and Charger
  • Mazda (two): CX-5 and MAZDA6
  • MINI (two): Cooper and Countryman

Other models receiving awards are Fiat 500; GMC Sierra HD; Infiniti QX80; Kia Sedona; Mercedes-Benz S-Class; Nissan Murano; and Volkswagen Golf.

The APEAL Study is used extensively by manufacturers worldwide to help them design and develop more appealing vehicles and by consumers to help them in their purchase decisions. It complements the J.D. Power Initial Quality Study (IQS), which focuses on problems experienced by owners during the first 90 days of ownership. The 2015 US APEAL Study is based on responses gathered between February and May 2015 from more than 84,000 purchasers and lessees of new 2015 model-year cars and light trucks who were surveyed after 90 days of ownership.

Efficient one-pot process to convert bio-oil fractions to gasoline-range hydrocarbons

Fri, 2015-07-24 10:33

A team at South China University of Technology has developed a one-pot process to convert the diesel distillate and residual oil fractions in bio-oil into high-quality fuels by catalytic hydrocracking with combined CoMoS/Al2O3 and HZSM-5 catalysts. A paper on their process is published in the journal Fuel.

Bio-oil—the end product of biomass pyrolysis—can be distilled into three fractions according to their boiling points—essentially light, medium and heavy. The light fraction is mostly water.

Under the conditions of 390 °C and 6 MPa H2, the researchers obtained a high yield (87.0 wt.%) of liquid products from the catalytic conversion of the medium and heavy fractions. The end product was C7–C14 hydrocarbons, including 23.3% of saturated naphthene; 23.4% of saturated chain hydrocarbons; 30.5% of aromatic hydrocarbons; and 22.8% of polycyclic aromatic hydrocarbons with one of ring saturated. The high heating value of products was 42.35 MJ/kg.

The amount of coking was only 1.15 wt.%, and the combined catalysts were recycled three times without the obvious decline of activity. Moreover, the reaction process did not need any solvent, and the products were easily separated.

Based on the material balance, the net hydrogen consumption for the hydrocracking process was 38 g of H2/kg of bio-oil, and the energy efficiency could reach up to 84%.

The results suggested that the approach provides a high-efficiency route for the preparation of high-quality hydrocarbon fuel from bio-oil.

Resources

  • Xianwei Zheng, Jie Chang, Yan Fu (2015) “One-pot catalytic hydrocracking of diesel distillate and residual oil fractions obtained from bio-oil to gasoline-range hydrocarbon fuel,” Fuel, Volume 157, Pages 107-114, doi: 10.1016/j.fuel.2015.05.002

  • Christian Lindfors, Eeva Kuoppala, Anja Oasmaa, Yrjö Solantausta, and Vesa Arpiainen (2014) “Fractionation of Bio-Oil” Energy & Fuels 28 (9), 5785-5791 doi: 10.1021/ef500754d

BYD to provide 50 e6 EVs to Opoli’s San Diego ride-sharing fleet

Fri, 2015-07-24 10:17

https://opoli.com , a ridesharing service and app based in San Diego, has partnered with China-based BYD Motors Inc, which will provide 50 of e6 EVs to the Opoli fleet as part of a green initiative. The BYD electric crossover will join Opoli’s natural gas airport shuttles late summer 2015. Opoli has been allotted charging spaces at the docking station at the San Diego International Airport.

This partnership comes weeks after Opoli launched services in the San Diego area, including being the first rideshare service permitted at the San Diego International Airport. Opoli functions under a name-your-price model, connecting drivers and ride seekers to agree upon a fare, with 100% of the fare going to the driver’s account. Rides can be booked in advance or on demand via the Opoli app, available for iOS and Android.

The e6 has been incorporated in fleets in Hong Kong, London, Singapore, Rotterdam, Bogota and Rio de Janeiro. BYD says that more than 800 are in operation as public eTaxis worldwide, with an accumulated fleet range of more than 45 million miles (72 million km).

The e6 is equipped with a 75kW motor and a 61.4 kWh BYD-developed lithium iron-phosphate battery, delivering a range of 186 miles (299 km) on a single charge under urban conditions. Top speed is 87 mph (140 km/h).

ICCT: ongoing cost reductions in full- and mild-hybrid systems could bring them into consumer mainstream by 2025

Fri, 2015-07-24 06:54

According to a new technology briefing paper on hybrid system technologies by John German at the International Council on Clean Transportation (ICCT), the costs of full-function hybrid systems are likely to drop to half the cost of their 2010 counterparts before 2025.

Combined with the development of mild-hybrid systems (belt-alternator or 48-volt system)s—which will likely provide one-half to two-thirds the fuel-efficiency benefits of full-function hybrids at less than half the cost—these levels of cost reductions could put both those technologies into the consumer mainstream by 2025, at least from a cost of technology point of view, German suggests.

Forty-five hybrid models were available in 2014 in the US; these captured about 2.75% of the overall US passenger vehicle market, down slightly from 3.19% in 2013. Hybrid market share is about 6% of vehicles sold in California—more than twice the national average—and about 20% in Japan (30% if the kei car segment is excluded).


Historical and projected hybrid system direct manufacturing cost. The purple line shows the estimated reductions for each new generation of the Prius. The green line reflects FEV’s 15% cost reduction for the power transmission/clutch/motor subsystems from 2010 to 2013, assuming that the same reductions are achieved in all parts of the hybrid system. The lighter dashed blue line projects future P2 hybrid system costs assuming that the 5% annual cost reduction continues into the future.

The darker blue lines illustrate an alternative path to similar cost reductions, with 2.5% annual cost reductions plus implementation of higher-power Li-ion batteries that should reduce future battery costs by at least $500.

Also shown on the graph are 2017 cost estimates for the P2 (light blue) and BAS (red) systems, plus the mild hybrid cost estimate range from Valeo (red circle). The red dashed line projects the mild hybrid cost estimates using the same 5% annual cost reduction. Click to enlarge.

Hybrids are far from a mature technology, and innovations and improvements are coming rapidly. Improved batteries designed with high power density for hybrid applications will start arriving soon. Hybrid systems other than the input power-split design pioneered by Toyota 17 years ago are still in early stages of development, and present huge opportunities to reduce cost through better designs, learning, and economies of scale.

… Because most hybrid systems are at a relatively early stage of development, costs are still relatively high and manufacturers are looking to recover some of the costs by charging customers a premium for hybrid vehicles. Thus, currently the hybrid system needs to offer a major improvement in fuel economy to entice customers to pay the price premium. This favors full-function hybrids and works against mild hybrid systems. However, in the future, lower cost, mild hybrid systems will be able to compete directly against conventional technology improvements on a cost-benefit basis. Thus, hybrid market penetration will likely increase only modestly in the near term, but as costs drop hybrids will become just another technology that manufacturers sell on its positive efficiency and drivability impacts, not on the technology itself, similar to what is currently occurring with turbocharged gasoline engines.—“Hybrid Vehicles: Technology Development and Cost Reduction”

Toyota currently dominates the US hybrid market, with some 66% of sales in 2014; Ford takes the second spot, with 14% of the market. Both use the same hybrid system design, an input power-split system. This type of system uses a planetary gear to distribute power between the engine, generator, traction motor, and drivetrain. This system excels in optimizing engine efficiency during city driving, the paper notes, and is also easily adaptable to plug-in operation. The downside is the cost associated for the two large electric motors and associated power electronics.

Other types of hybrid systems are in earlier stages of development and deployment. Nissan, Hyundai/Kia, VW/Audi/Porsche, BMW, Subaru, and Mercedes all recently introduced variants of a single-motor, twin-clutch hybrid system (P2). Hyundai/Kia, with 8% of total 2014 hybrid sales, is so far the leading seller of P2 hybrids; P2 hybrid market share grew from 9% in 2013 to 12% in 2014.

Hybrid systems can reduce fuel consumption and CO2 emissions by up to 35%, equivalent to more than a 50% increase in fuel economy, German notes, with the precise reduction varying with the sophistication of the hybrid system. Further, German observes:

The Vincentric Hybrid Analysis provides a direct comparison of the efficiency benefits and costs of hybrid systems. For any individual model the difference in efficiency between the hybrid model and the non-hybrid comparable may be affected by differences in powertrain, weight, tire rolling resistance, and aerodynamic drag. For example, all of the Toyota hybrid systems are similar, yet the calculated fuel consumption reduction ranged from 24% on the Lexus RX450h to 47% on the Lexus CT 200h.

While conducting a detailed analysis of the possible bias for each hybrid vehicle comparison selected by vincentric is beyond the scope of this report, it is clear that in some cases the non-hybrid vehicle has lower performance and fewer consumer features than the hybrid vehicle (such as the Honda Accord) and in other cases the non-hybrid vehicle has higher performance and features (such as the Lincoln MKZ). If these offsets are random and are not systematically biased, averaging the data by manufacturer should reduce the bias in the results, although the amount of bias is still unknown.

Correspondingly, consumer payback for hybrid purchases, in terms of fuel savings versus hybrid price premium, also varies widely from vehicle to vehicle. Currently, roughly 29% of hybrid models (9 out of 31) pay back the initial hybrid price premium with fuel savings within 5 years. Roughly 61% of hybrid models (19 out of 31) pay back within the full useful life. On average, German says, the fuel savings over the full useful life are about $1,300 more than the initial price premium.

However, the roughly 3% market share for hybrids suggests that the fuel savings are not large enough to motivate most customers to pay for the incremental cost. Hybrids also face the rising challenge of improved conventional vehicles. On the other hand, German observes:

The tenfold increase in hybrid sales from 2003 to 2013 suggests that many of the early concerns about hybrids, such as reliability, battery life, resale value, and safety, have been successfully addressed. In addition, the electric motor provides instant torque, improving drivability and performance especially at low speeds, which is a desirable feature. Thus, the key to increased hybrid market share is simply getting the cost down and improving the payback.

Promising technology developments for cost reduction. There are several developing technology areas that offer the promise of cost reduction, including batteries with higher power density; design improvements for P2 hybrids, and lower-cost 48V hybrid systems.

  • Battery subsystems are a significant part of the cost of hybrid systems—about $1,375 for a 1.0 kWh Li-ion pack. New cell chemistries optimized for high power have been in development for several years and should reach the market as early as this year. Instead of 1.0 kWh, future high-power Li-ion batteries for typical full-function hybrid applications should be only about 0.3 to 0.5 kWh, German says. These high-power batteries will cost more per kWh than current Li-ion designs, but the cost savings should still be at least $500.

  • While the input power-split hybrid design used by Toyota and Ford is in its fourth generation, first-generation P2 hybrids are at a much earlier point on the learning curve. This opens the possibility for significant cost improvement.

    For example, all current P2 hybrids install the motor between the engine and the transmission. Although this minimizes the amount of redesign required, it requires a separate case, cooling system, oiling system, and clutch for the motor. It also compromises powertrain packaging. Installing the motor and other hybrid components inside the transmission will result in large cost reductions and packaging improvements.

    Additional opportunities to reduce cost and improve efficiency in the future include removing the torque converter, use of a less expensive conventional manual transmission (enabled by using the electric motor to fill in the engine torque gaps), and less expensive designs to coordinate the friction brakes and regenerative braking.

  • More sophisticated and better-optimized mild hybrid systems offer the greatest opportunity to improve hybrid cost-effectiveness, German says. Manufacturers and suppliers are still sorting out the relative advantages and costs of the many different possible configurations, such as voltage level (12V–48V); energy storage (lead-acid, lead-acid plus ultracapacitors, NiMH, Li-ion) and drive type (BAS or P2 configurations). An additional advantage of 48V systems is that they can power an electric motor integrated within the turbocharger to reduce turbo lag and improve turbocharged engine efficiency and response.

Because most hybrid systems are at a relatively early stage of development, costs are still relatively high and manufacturers are looking to recover some of the costs by charging customers a premium for hybrid vehicles. Thus, currently the hybrid system needs to offer a major improvement in fuel economy to entice customers to pay the price premium. This favors full-function hybrids and works against mild hybrid systems. However, in the future, lower cost, mild hybrid systems will be able to compete directly against conventional technology improvements on a cost-benefit basis. Thus, hybrid market penetration will likely increase only modestly in the near term, but as costs drop hybrids will become just another technology that manufacturers sell on its positive efficiency and drivability impacts, not on the technology itself, similar to what is currently occurring with turbocharged gasoline engines.—“Hybrid Vehicles: Technology Development and Cost Reduction”

International Truck invites Class 8 competitors to open event for head-to-head testing on fuel economy, aerodynamics and drivability

Fri, 2015-07-24 05:00

International Truck (Navistar’s flagship vehicle brand) has invited each of its Class 8 competitors to participate in an open performance testing to compare fuel economy and drivability of their new trucks during the week of 31 August at the Navistar Proving Grounds in New Carlisle, Indiana. Competitors will have the opportunity to bring their two best performing vehicles with regards to fuel economy and drivability.

The vehicle specifications for the test include: Class 8, on-highway sleeper; model year 2016, calendar year 2015 builds; include only factory installed options (hardware, software, and fluids), and currently meet compliance and are capable of delivery to all customer applications; and must fall within total mileage range of 2,500 – 15,000 miles (4,000 - 24,000 km) to maintain consistent break-in levels.

Fuel economy testing will occur on a closed-track at the Navistar Proving Grounds and will follow the protocols called out by SAE International Recommended Practice “Joint TMC/SAE Fuel Consumption In-Service Test Procedure Type III (SAE J1526).”

The test will be executed with a gross combination weight (GCW) of approximately 65,000 lbs. and the vehicle will be driven at typical highway operating speeds. Drivers and trailers will be switched from “Control” to “Test” vehicle between test segments. Tires will be standardized across all vehicles and will be provided by Navistar, sets will be randomly assigned for each vehicle. Trailers will also be standardized and provided by Navistar for all units.

Aerodynamic Coastdown testing will be performed at the Navistar Proving Grounds and will follow the recommended practices SAE 1263, “Road Load Measurement and Dynamometer Simulation Using Coastdown Techniques” and SAE 2263, “Road Load Measurement Using Onboard Anemometry and Coastdown Techniques.”

A tire set specifically for coastdown testing will be standardized across all vehicles and will be provided by Navistar. A coastdown dedicated trailer will also be used for all vehicles and will be provided by Navistar along with necessary instrumentation.

Additional areas being tested will include ride vibration and harshness, curb-to-curb cornering ability, forward visibility and interior noise.

We’re all proud of our trucks, and I believe that running our vehicles in an open and transparent forum, side-by-side, will not only raise the water mark but will also benefit each of our customers in this industry.—Jeff Sass, Navistar Senior Vice President North America Trucks Sales & Marketing

New heat exchanger for supersonic aircraft engines

Fri, 2015-07-24 04:48

High-performance aircraft turbine engine manufacturers are facing unprecedented increases in the amount of heat that must be released in order to maintain acceptable temperatures in supersonic engines that is required for the aircraft to operate at optimum levels. A professor in Purdue’s School of Mechanical Engineering has developed a heat exchanger that could use aircraft fuel to cool hot engine components in order to alleviate the increasing temperatures.

Issam Mudawar said hot engine components are generally cooled by air that is bled from the engine's compressor, but this type of system does not work for high-performance engines.

Cooling an engine with air from the aircraft’s compressor is not viable for high-performance engines since the compressor air at supersonic speeds is too hot itself. My technology uses the aircraft fuel to cool the compressor air before it is used to cool the hot engine components in the aircraft. —Issam Mudawar

>The technology consists of a heat exchanger that is composed of a multitude of modules in which the cold fuel is passed through internal mini-channels and the hot air is passed in cross-flow along the finned outer surface, Mudawar said. The heat exchanger is compact and lightweight, and possesses very high heat transfer performance. Its modules can be configured in many possible ways to suit the engine’s packaging requirements.


Mudawar hopes to attract funding from companies that have significant interest in both funding and implementing this technology.

Mudawar’s technology has been patented through the Purdue Research Foundation Office of Technology Commercialization.

Honda opens new Silicon Valley facility to advance connected mobility; refreshed 2016 Accord; Honda Xcelerator

Fri, 2015-07-24 04:00

Honda officially opened its new Silicon Valley R&D facility, using the occasion to unveil a refreshed 2016 Accord featuring Honda’s first application of Apple CarPlay and Android Auto. Honda also announced a new open innovation R&D initiative—Honda Xcelerator—which will provide resources to breakthrough technology innovators to help rapidly develop prototypes with the potential to transform the automotive experience.

Honda’s Silicon Valley operation, which was first established in 2000, is charged with researching and prototyping innovations and harnessing new ideas and technology. Current areas of focus include connected mobility; novel human-machine interfaces; supporting app developers through initiatives such as Honda Developer Studio; and computer science research for vehicle intelligence. Silicon Valley engineers also spearhead the company’s working relationship with Silicon Valley-based technology companies.

As an industry, we are on the verge of some major transformational changes brought on by the convergence of what have been, to this point, largely disparate technology disciplines. Honda will embrace and help lead this convergence. Our operations in Silicon Valley are a testimony to our focus on this new direction in our product and technology development efforts.—||Honda R&D Americas President, Frank Paluch. "

Accord. The 2016 Accord will be the first Honda model and among the first high-volume cars in the marketplace to feature both Apple CarPlay and Android Auto, among major upgrades that will make the 2016 Accord the most high-tech Accord yet.

For model year 2016, the reigning best-selling car in California also will receive Honda Sensing, the comprehensive suite of safety and driver-assistive technologies that helps reduce driver workload and avoid or mitigate the severity of a vehicle collision. (Earlier post.) Honda Sensing also serves as both a technological and perceptual bridge to highly automated cars of the future.

Honda Xcelerator. Honda Xcelerator is designed to engage innovators and help them more rapidly commercialize breakthrough technologies. The program provides funding for proof-of-concept prototyping and the opportunity to work directly alongside Honda engineers in Silicon Valley in a collaborative workspace, as well as pairing with Honda mentors.

Innovators will also have the opportunity to pitch their technologies to Honda business units globally once their prototypes are developed. Interested innovators should visit the new Honda Xcelerator website at xcelerator.hondasvl.com to learn more.

UNI-CUB Application Program Interface (API) launched. Expanding the open innovation theme, Honda also announced the upcoming release of a remote API for the Honda UNI-CUB, a unique personal mobility device that features Honda’s original balance control technology and an omni-directional driving wheel system. Beginning in the fall, this new remote API will allow developers to control UNI-CUB from external devices and develop new use cases for UNI-CUB. The UNI-CUB API will be released by the Honda Developer Studio.

Advanced Technology Demos. At the event, Honda also demonstrated several advanced technologies under three distinct themes: Future Technology, Open Innovation and Honda Dreams.

  • The Future Technology section included a demonstration of the ability for sensor fusion technology accurately to detect and to predict bicyclist and pedestrian movement from a significant distance.

  • The Open Innovation section included a novel demonstration of rear seat entertainment in a virtual reality world. The demo uses a virtual reality headset to transport passengers into a virtual world featuring Honda products on the land, sea and air. As the test vehicle moves, the passenger synchronously glides through the virtual environment.

  • In the Honda Dreams section, several units of the Honda UNI-CUB were on-hand for guests to test.

dryclean -- Demonstration Program Notice 2015-1: AB 998 Demonstration Program

Thu, 2015-07-23 19:15
The California Air Resources Board (CARB) announces the Demonstration Program Notice 2015-1: AB 998 Demonstration Program for the dry cleaning industry.

newsclips -- ARB Newsclips for July 23, 2015.

Thu, 2015-07-23 16:58
ARB Newsclips for July 23, 2015.

Researchers show use of MFRE can at least double wireless power transfer efficiency; more efficient than metamaterials

Thu, 2015-07-23 13:30

Researchers at North Carolina State University and Carnegie Mellon University have shown that passing wireless power transfer through a magnetic resonance field enhancer (MR-FE)—which could be as simple as a copper loop—can at least double transfer efficiency as compared to transferring through air alone. MR-FE use could potentially boost transfer efficiency by as much as 5,000% in some systems, the researchers said.

Wireless power transfer works via magnetic coupling or inductive coupling, and can achieve very high efficiency when the distances between the transmitter and receiver are small—less than a few centimeters. In such a case, the transmitter and receiver are strongly coupled, with a high coupling coefficient (usually greater that 0.9). As distance increases, the strength of the coupling decreases. Enhancing wireless power transfer efficiency over greater distances—to support, for example, the wireless charging of electric vehicles—has thus been a major goal of many research groups.

One of the leading candidates proposed for enhancing efficiency has been the use of metamaterials (MM)—artificial structures with particular electromagnetic properties—between transmitter and receiver.

The NCSU/CMU analysis, however, shows that the MR-FE approach can have up to a 4 times higher efficiency over the MM approach due to the lower loss of its field enhancement mechanism, said David Ricketts, an associate professor of electrical and computer engineering at NC State and corresponding author of a paper describing the work.


From left to right: performance of wireless power transfer using an MR-FE, a metamaterial (MM), and through air alone. Click to enlarge.

By placing the MR-FE between the transmitter and the receiver (without touching either) as an intermediate material, the researchers were able to significantly enhance the magnetic field, increasing its efficiency.

We realized that any enhancement needs to not only increase the magnetic field the receiver ‘sees,’ but also not siphon off any of the power being put out by the transmitter. The MRFE amplifies the magnetic field while removing very little power from the system.—David Ricketts

The researchers conducted an experiment that transmitted power through air alone, through a metamaterial, and through an MR-FE made of the same quality material as the metamaterial. The MR-FE significantly outperformed both of the others. In addition, the MRFE is less than one-tenth the volume of metamaterial enhancers.

This could help advance efforts to develop wireless power transfer technologies for use with electric vehicles, in buildings, or in any other application where enhanced efficiency or greater distances are important considerations.—David Ricketts

Lead author of the paper is Matthew J. Chabalko, who worked on the project as a postdoctoral researcher at Carnegie Mellon and now works at Disney Research. Jordan Besnoff, a postdoctoral researcher at NC State, is a co-author of the paper.

Resources

  • Chabalko, M.; Besnoff, J.; Ricketts, D. (2015) “Magnetic field enhancement in wireless power using metamaterials magnetic resonant couplers.,” Antennas and Wireless Propagation Letters, IEEE vol. PP, no.99, pp. 1 doi: 10.1109/LAWP.2015.2452216doi:

  • Guy Lipworth, Joshua Ensworth, Kushal Seetharam, Da Huang, Jae Seung Lee, Paul Schmalenberg, Tsuyoshi Nomura, Matthew S. Reynolds, David R. Smith & Yaroslav Urzhumov (2014) “Magnetic Metamaterial Superlens for Increased Range Wireless Power Transfer” Scientific Reports 4, Article number: 3642 doi: 10.1038/srep03642

  • Wang, B.; Teo, K.H.; Nishino, T.; Yerazunis, W.; Barnwell, J.; Zhang, J. (2011) “Wireless Power Transfer with Metamaterials” TR2011-052

Navigant forecasts global natural gas refueling stations to grow from 23,001 in 2015 to 38,890 in 2025

Thu, 2015-07-23 12:06

In a new report, Navigant Research forecasts that the total number of global NGV refueling stations is expected to grow from 23,001 in 2015 to 38,890 in 2025, with a compound annual growth rate (CAGR) of 5.4%. More than 80% of these stations are expected to be CNG stations to support light-duty NGVs, which are projected to account for 90% of the NGV fleet at the end of the forecast period.

The report covers the global market for refueling infrastructure for natural gas vehicles (NGVs), including light duty (LD), medium duty (MD), and heavy duty (HD) vehicles with four or more wheels and full-speed capability.

Three types of refueling infrastructure are included: fast-fill (high pressure) compressed natural gas (CNG), slow-fill (low pressure) CNG, and cryogenic liquefied natural gas (LNG).

There are a wide range of companies involved in the entire supply chain for NGV refueling infrastructure, including equipment manufacturers, gas suppliers, station operators, and consultants that support planning and construction of stations. Many of the key components involved in the refueling infrastructure are also used elsewhere in the production, transmission, and consumption of NG for energy production, industrial use, and residential use. As a result, many of the key players are not entirely dependent on the growth of NG as a transportation fuel, which should help them through any fluctuations in demand.—“Natural Gas Vehicle Refueling Infrastructure”

Federal-Mogul Powertrain to showcase hollow-stem valves for higher engine temperatures and increased peak cylinder pressures

Thu, 2015-07-23 11:51

Federal-Mogul Powertrain, a division of Federal-Mogul Holdings Corporation (NASDAQ: FDML), will exhibit its newly acquired engine valve technology for the first time at the 2015 IAA show in Frankfurt in September. Among the components produced by the company’s Global Valvetrain business are sodium-cooled valves with exceptionally small stem diameters that deliver both reduced weight and greater resistance to the high temperatures that can be a limiting factor in highly rated downsized engines.

Unlike a conventional valve with a solid stem, which conducts almost 75% of its heat away through the head and seat, Federal-Mogul Powertrain’s hollow stem technology reduces the heat flow through the valve head to around 50% of the total by transmitting a greater share through the stem and guide. This allows the valve head to run between 80°C and 150°C cooler.

Primarily applied to exhaust valves to facilitate temperature reduction, the hollow valves can also be used on the intake side to save weight. Federal-Mogul uses different material combinations to provide maximum corrosion resistance or high temperature durability and the technology is also fully compatible with established treatments for wear resistance such as nitriding, chrome plating and hard facing.

Advanced high-precision deep hole drilling combined with friction welding manufacturing techniques enable Federal-Mogul Powertrain to produce the hollow stems in sizes as small as 5mm diameter. This means that even engines with small cylinder bores, such as downsized units or high performance motorcycles, can be accommodated.

Although already established for many years in motorsport applications, making this technology available for volume production passenger cars required particular manufacturing expertise in order to combine the necessary quality and robustness levels into a cost-effective product. The use of a single weld to close the hollow cavity was key to achieving the design solution for series production.

“Hollow valve stems are both an enabling technology and a direct contributor to the reduction of CO2 emissions; by lowering the valve head temperature they allow more efficient downsizing strategies and by reducing mass they cut the energy absorbed through friction.—Gian Maria Olivetti, Chief Technology Officer, Federal-Mogul Powertrain

DLR and Wuppertal publish comprehensive global analysis of e-mobility technologies, outlook and lifecycle assessments

Thu, 2015-07-23 11:33

The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) and the Wuppertal Institute for Climate, Environment and Energy (Wuppertal Institut für Klima, Umwelt, Energie GmbH; WI) have published results of their STROMbegleitung (electricity evaluation) comprehensive study to analyze technologies; market outlook; policy support; infrastructure; and life-cycle assessments for electrically-powered transport.

The study, which ran from October 2011 – September 2014, comprehensively charts current progress in technology; identifies trends; analyzes lifecycle assessments for a variety of vehicle concepts; and assess material intensities. At the same time, it places German activities in the field of electromobility within an international context. The research program received a €1.7 million euro grant from the German Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung; BMBF) as part of the STROM support program (key technologies for electromobility).


From the STROMbegleitung report: operating points of a BEV in simulated ride through the CADC highway cycle applied to the efficiency map of an electrical machine. The dashed line on the operating map show rated torque; the solid line shows peak torque. Click to enlarge.

Trend analysis. Within the study, the DLR scientists developed a database to record all electric passenger vehicles, which they analyzed down to the component level—including series vehicles already in production, prototypes, show cars and research vehicles. They counted more than 500 electric passenger vehicles of all those types worldwide in the period from 2000 to 2013.

A total of 87 new BEV and PHEV production cars were presented worldwide between 2006-2013.


Number of series-production electric vehicles by OEM, 2000-2013. Click to enlarge.

The focus was in particular on electrical machinery, power electronics and various technologies for traction batteries. The study found that activities of international car manufacturers in the field of electrified vehicle concepts (XEV) worldwide increased significantly for the first time from 2006 and especially from 2009 onwards.

However, from 2012, the study found an annual decline in newly introduced vehicles. Non-plug-in hybrid electric vehicles (HEVs) showed a fairly constant number in the analysis; plug-in hybrids (PHEVs) accounted for the largest share of new concept vehicles in 2013.


Annual number of internationally presented electrified vehicles. Click to enlarge.

The study also found that increasing vehicle mass is correlated with a decreasing degree of electrification. Full battery-electric vehicles are mainly found in vehicles under 1000 kg (2200 lbs); the proportion of HEVs increases significantly with heavier vehicles. The largest share of PHEVs were found between a vehicle curb weight of 1500 kg (3,300 lbs) and 2000 kg (4400 lbs).


Degree of electrification by vehicle manufacturers. Click to enlarge.

The analysts also found nearly 52,000 publications and 82,000 patents in the field of hybrid and electric vehicles over a period of 10 years.

At the moment, the automobile industry in Japan and the United States is pioneering the development of marketable vehicle models; they also produce the highest-selling models on the market. 210,000 vehicles with an external capacity to charge the battery (plug-in hybrids and battery-powered electric vehicles) were sold worldwide in 2013—roughly half of them in the United States, which is currently the largest market.


Production of electric vehicles by country. Click to enlarge.

The study indicates that Germany is lagging behind in the research and development of key technologies, especially in the field of power electronics. Here, Japanese companies in particular are driving technological development.

Power electronics are crucial to electric cars; these components control and direct the flow of energy within the vehicle, and are therefore important elements in any further optimisation of the powertrain. This is why enhanced research into components and materials used in power electronics needs more support here in Germany.—Matthias Klötzke, study project coordinator

Klötzke adds that Germany occupies a strong position in terms of assembly and packaging technology as well as system integration, noting that an additional characteristic feature of the electromobility sector in Germany is the close cooperation between research institutions, manufacturers and medium-sized enterprises. This area should also receive additional support. An analysis of ongoing and announced support programs indicates that Germany already shows the highest levels of investment in research and development within the electromobility sector in Europe.

Rare earth elements and lithium—raw material shortages predicted. Many electric vehicles use permanent magnets based on rare earth elements. These rare magnets exhibit a high energy density and are lighter than magnets made of other materials. The availability of rare earth elements varies greatly; while some are available on the global market from various sources, others are highly dependent on just a few source countries, China in particular.

To expand electromobility, we need to consider alternative motor designs and recycling methods for particularly scarce raw materials, and we have to search for alternative materials.

Lithium-ion batteries are currently used in approximately 80% of electric vehicles, and therefore represent the dominant technology by far. Batteries installed in electric vehicles will continue to use this technology in future; this creates a situation quite similar to that of rare earth elements.

Demand for lithium is reaching a critical level in all scenarios of electromobility considered in the study. Hence, the researchers anticipate a rise in costs and greater levels of pollution in mining operations designed to extract the metal. They recommend continuing the efforts to develop recycling methods for lithium, expanding their application and introducing support programs to conduct research into alternative battery technologies and energy sources.

Resources

Iranian team proposes intelligent control strategy for hybrids using fuzzy driving cycle identification agent

Thu, 2015-07-23 06:41

Researchers at the University of Tehran (Iran), with colleagues at Isfahan University of Technology and Iran University of Science and Technology, are proposing a new intelligent control strategy for the energy management of hybrid powertrains based on the driving cycle type. As described in a paper in the Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering they use similarity weights to compare every instance of an unknown driving cycle to the reference driving cycles.

The weights, which are between zero and one, are determined using a fuzzy driving cycle identification agent based on the comparison of preselected driving features. To determine the control output in the unknown driving cycle, the weights are applied to a linear combination of the optimal control decisions generated in each of the reference driving cycles.

Simulation studies in seven different driving cycles showed that, while all driving patterns in every driving cycle are considered for the generation of energy management by online implementation of the proposed intelligent control strategy, some driving patterns would be eliminated by using a non-fuzzy identification agent.

This, they said, leads to a significant reduction in the fuel consumption of the hybrid powertrain utilized with the fuzzy identification agent in some driving cycles in comparison with those without the use of non-fuzzy driving cycle identification. In addition, in some driving cycles, the intelligent control strategy has a performance close to that for the offline optimized control strategy.

Resources

  • Ali Safaei, Mohammad Reza Ha’iri-Yazdi, Vahid Esfahanian, Mohsen Esfahanian, Masood Masih Tehrani, Hassan Nehzati (2015) “Designing an intelligent control strategy for hybrid powertrains utilizing a fuzzy driving cycle identification agent” Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering vol. 229 no. 9 1169-1188 doi: 10.1177/0954407014556116

BGU, UWA researchers develop faster and more efficient system to produce graphene for energy storage applications

Thu, 2015-07-23 06:03

Ben-Gurion University of the Negev (BGU) and University of Western Australia (UWA) researchers have developed a new process to develop few-layer graphene for use in energy storage and other material applications that is faster, potentially scalable and surmounts some of the current graphene production limitations.

Graphene is a thin atomic layer of graphite with numerous properties that could be valuable in a variety of applications, including medicine, electronics and energy. Discovered only 11 years ago, graphene is one of the strongest materials in the world, highly conductive, flexible, and transparent. However, current methods for production currently require toxic chemicals and lengthy and cumbersome processes that result in low yield that is not scalable for commercial applications.

The new one-step, high-yield generation process is detailed in the latest issue of Carbon, published by a collaborative team that includes BGU Prof. Jeffrey Gordon of the Alexandre Yersin Department of Solar Energy and Environmental Physics at the Jacob Blaustein Institutes for Desert Research and Prof. H.T. Chua's group at the University of Western Australia (UWA, Perth).

Their ultra-bright lamp-ablation method surmounts the shortcomings and has succeeded in synthesizing few-layer (4-5) graphene in higher yields. It involves a novel optical system (originally invented by BGU Profs. Daniel Feuermann and Jeffrey Gordon) that reconstitutes the immense brightness within the plasma of high-power xenon discharge lamps at a remote reactor, where a transparent tube filled with simple, inexpensive graphite is irradiated.

The process is relatively faster, safer and green—devoid of any toxic substances (just graphite plus concentrated light).

Following this proof of concept, the BGU-UWA team is now planning an experimental program to scale up this initial success toward markedly improving the volume and rate at which few-layer (and eventually single-layer) graphene can be synthesized.

Resources

  • Haibo Lu, Wei Sheong Woi, Xunyan Tan, Christopher T. Gibson, Xianjue Chen, Colin L. Raston, Jeffrey M. Gordon, Hui Tong Chua (2015) “Synthesis of few-layer graphene by lamp ablation,” Carbon, Volume 94, Pages 349-351 doi: 10.1016/j.carbon.2015.07.004

Researchers fabricate high-performance 3D silicon anodes for Li-ion batteries from reed leaves

Thu, 2015-07-23 06:00

Nanoporous silicon is considered an attractive next-generation anode material in lithium-ion batteries due to its much higher theoretical capacity and lower operating voltage than the commonly used graphitic carbon materials. However, one challenge ia finding a suitable low-cost strategy to employ an appropriate nano-structured silicon material that would compensate for the large volume expansion upon lithium insertion.

Researchers at Max Planck Institute for Solid State Research, the University of Science and Technology of China, and the South China University of Technology have taken a novel approach—one quite distinct from elaborate physical or chemical treatments of expensive silicon precursors. The team led by Prof. Yan Yu fabricated 3D porous silicon-based anode materials from natural reed leaves using calcination and magnesiothermic reduction.

The resulting silicon anode retains the 3D hierarchical architecture of the reed leaf, and features an interconnected porosity and inside carbon coating. The anodic material exhibits high specific capacity, very good rate capability, and cycling stability, just as it is required in advanced lithium-ion batteries. Even after 4,000 cycles and at a rate of 10C, the anode achieved a specific capacity of 420 mAhg-1.

A paper describing their work is published in Angewandte Chemie International Edition.


a) Flow chart showing conventional synthesis routes of nano-Si for Li-ion battery anodes, along with of the sustainable and low-cost synthesis route from natural reed leaves. b) Detailed flow chart of the process for 3D porous Si-C anode from natural reed leaves to the 3D porous SiO2 precursor and finally the 3D porous Si-C anode. Source: Liu et al.Click to enlarge.

While a manifold of silicon-based nanostructured anodes with very good electrochemical performances have been successfully fabricated, most of them lack potential of practical application owing to the high cost of precursors and methodology or the inability to produce materials at gram or even kilogram level.

… Plants can absorb silicon in the form of silicic acid (Si(OH)4 or Si(OH)3O-) from the soil. The ability of a plant to accumulate silicon varies greatly from species to species (0.1–10 % of shoot dry weight). Silicon accumulation exceeding 4% is especially common in monocotyledonous plants, and hence in the plant families of Poaceae, Equisetaceae, and Cyperaceae. Reeds, as the typical members of the Poaceae family, grow in along rivers, or in shallow water near ponds. They are widely distributed worldwide in the wetland of the temperate regions. As a living plant, reeds absorb silica from soil, and the silica accumulates around cellulose microcompartments. Therefore, reeds are suitable natural reservoirs of nano-structured silica and its derivatives. Yet they are not only appropriate Si sources, they also contain silica in a very favorable nanoscale arrangement.

… reed leaves exhibit well-defined sheet-like 3D hierarchical micro- structures, which as we demonstrate can be transformed into a well-suited 3D highly porous hierarchical Si architectures.—Liu et al.

Synthesis is based on magnesiothermic reduction of 3D porous SiO2 converted from natural reed leaves. It utilizes the reed leaf as skeleton template, and the in situ generated MgO by-products as pore template.

Compared with the reported methods of producing nanostructured Si anodes, the reed-based method offers a number of advantages, the researchers said:

  1. reed leaves are sustainable materials source;
  2. the recovered silicon retains the favorable 3D silica nanostructure of the reed leaves (which allows for superior battery performance by mitigating pulverization);
  3. the overall method is simple; and
  4. the overall process does not use expensive Si precursors or reagents.

Electrochemical performances of highly porous 3D Si-C nanonet anodes. a) CV curves at a scanning rate of 0.1 mVs-1 in the voltage range of 0.01–1.0 V. b) voltage–capacity curves at 0.05 C and 0.5 C rates. c) Rate capability at different rates (increased from 0.2 C to 20 C after the first three CV cycles). d) Cycling performances at 0.5 C rate (first activated with two cycles at 0.05 C). e) Long-term cycling performance of the highly porous 3D Si-C nanonet electrode at a current density of 10C. Liu et al. Click to enlarge.

The topological architecture of the original silicates within the reed leaves is extraordinarily well preserved during the applied chemical and physical treatment steps. Upon the purification from the dry reed leaves, the three-dimensional structure only shrinks, but retains its mesoporous network. It does not even change during the reduction to the final carbonized silicon network.

The magnesiothermic reduction has two advantages. First it results in a silicon microstructure retaining the original silicic structure. Second, etching of the MgO inclusions leads to a high internal pore density. These features together with the carbon coating of the silicon leads to the attractive electrochemical performance for Li-ion batteries, such as large reversible capacity, high rate capability, and superior cyclability. The 3D hierarchical architecture and 2D highly porous nanosheet/nanonet units buffer the huge volume change, reduce the diffusion-induced stress, and facilitate the diffusion of Li ions and electrolyte into the electrode. The surface carbon coating enhances not only the overall electronic conductivity of Si but also mechanically stabilizes the whole 3D porous structure. Moreover, given the sustainable and facile nature of the synthesis procedure, the described 3D porous Si-C nanocomposite has a great potential as a practical anode material for Li-ion batteries.—Liu et al.

Resources

  • Jun Liu, Peter Kopold, Peter A. van Aken, Joachim Maier, and Yan Yu (2015) “Energy Storage Materials from Nature through Nanotechnology: A Sustainable Route from Reed Plants to a Silicon Anode for Lithium- Ion Batteries” Angew. Chem. Int. Ed. 54, 1 – 6 doi: http://dx.doi.org/10.1002/anie.201503150

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