Volvo Cars starts development of fuel cell/on-board reformer range extending system for EVs

Backed by research support from the Swedish Energy Agency, Volvo Cars isinitiatingdevelopment of a fuel cell system that can extend an electric car’s operating range . The aim is to have two prototype chassis based on the Volvo C30 DRIVe Electric ready for testing in everyday traffic in 2012.

Volvo Cars is working together with the companyPowerCell Sweden ABon this project. In the first phase, a preliminary study is being conducted into a fuel cell range extender, consisting of a fuel cell with an on-board reformer—i.e., a version of the PowerCell Power Pac. The reformer converts a liquid fuel, in this case gasoline, to hydrogen reformate, which then fuels the stack.

The technology generates electricity completely without any emissions of carbon oxide (CO), nitrogen oxides (NO_x), sulphur oxides (SO_x) and particles. Due to system efficiency, emissions of carbon dioxide (CO₂) are significantly reduced compared with a conventional vehicle, according to Volvo. The technology also can be adapted for renewable fuels.

In the next phase, pending support from the Swedish Energy Agency, Volvo Cars and PowerCell will produce two test cars based on the current Volvo C30 DRIVe Electric. Testing of the cars will begin in 2012.

This is an exciting expansion of our focus on electrification. Battery cost and size means that all-electric cars still have a relatively limited operating range. Fuel cells may be one way of extending the distance these cars can cover before they need to be recharged. What is more, the project gives us increased knowledge about fuel cells and hydrogen gas.

—Volvo Cars President and CEO Stefan Jacoby

This technology is expected to increase the electric car’s operating range by up to 250 kilometers (155 miles) in addition to the range provided by the car’s battery pack. The fuel cell industry expects that the cost efficiency will improve continuously through refined technology and large-scale production.

We have just taken the first steps and it is naturally too early to talk about market introduction of electric cars with Range Extenders. The industrial decision will come after we have learned more about fuel cells and the opportunities they offer.

—Stefan Jacoby

A PowerCell APU. The Click to enlarge.

PowerCell AB.PowerCell Sweden AB was founded as a joint venture between AB Volvo and Statoil ASA with the objective of bringing fuel cell and fuel converter technology to full commercialization. In 2009, Volvo Technology Transfer invested in the company, along with Midroc New Technology, Ocas Ventures and Fouriertransform. (Earlier post.)

PowerCell plans to supply its Power Generator (reformer plus fuel cell stack) to two main market segments in the transport industry, the Marine leisure and the Truck segment, as an APU.

PowerCell Sweden’s technology is based on two patented components: the fuel converter (reformer) and the PEM fuel cell stack. The autothermal reformer was originally developed by OWI (Oel Waerme Institut) in Aachen, while the PEM fuel cell was developed at Volvo. Currently available with up to 7 kW output, the next generation of the fuel cell, currently under development, will output up to 30 kW.

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=> Volvo Cars starts development of fuel cell/on-board reformer range extending system for EVs.

PNNL Researchers Developing High-Capacity Silicon Anode Material Using Micrometer-sized Particles with Nanopore Structure; 1600 mAh/g After 40 Cycles

Scientists at the US Department of Energy’s Pacific Northwest National Laboratory (PNNL) have developed a silicon-based anode material for Li-ion batteries using micrometer-sized silicon particles with a nanopore structure. The material shows reversible capacity of more than 1,600 mAh/g after 40 charging/discharging cycles.

With a theoretical capacity some 10 times that of graphite, silicon anodes could contribute to a doubling of the capacity of graphite-anode Li-ion batteries. However, a silicon anode experiences a large volume expansion during lithium-ion insertion and a consequent shrinkage during extraction; this leads to severe particle pulverization, resulting in quick failure of the electrode structure and resulting capacity fade with cycling. Accordingly, a numerous efforts are underway to devise a structure and a material resistant to those changes.

Dr. Jason Zhang and the PNNL research team are addressing that challenge by designing a silicon particle architecture that would maintain structural integrity. The porous structure of the Si helps accommodate the large volume variations that occur during the Li insertion/extraction processes.

Chemical vapor deposition (CVD) of carbon coatings and highly elastic Ketjen Black (KB) carbon were used to improve the electrical conductivity throughout all cycling stages. The team placed these anodes between graphene—planar sheets of bonded carbon atoms—to maintain strong electrical contact between silicon particles.

The combination of the nanopore structure, CVD-coated carbon on the Si surface, and the elastic carbon (KB) among the silicon particles provides a cost-effective approach to utilize the large micrometer-sized Si particles in Li-ion batteries.

—Xiao et al.

 

The PNNL research team continues to improve the performance and long-term stability of the silicon anodes from 40 to 50 charging/discharging cycles today to a goal of about 500 cycles in the future. One solution may be the development of a better binder that can maintain improved mechanical and electrical contact. This method has potential for much greater cyclability while maintaining high energy density.

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=> PNNL Researchers Developing High-Capacity Silicon Anode Material Using Micrometer-sized Particles with Nanopore Structure; 1600 mAh/g After 40 Cycles.

Toshiba To Develop EV Batteries With Fiat, Scania; New 60 Ah Cell

Nikkei. Toshiba Corp. will jointly develop lithium-ion batteries for hybrid vehicles with Fiat SpA and also with Scania AB, majority-owned by Volkswagen AG. Toshiba is currently co-developing batteries and other components with Volkswagen (earlier post).

Earlier this week, Toshiba celebrated the opening of its new plant in Kashiwazaki that will manufacture its SCiB Li-ion batteries. (Earlier post.) Initial production capacity is for 50 million cells per month; during fiscal year 2011, production capacity will increase to more than 100 million cells monthly.

60 Ah cell. Toshiba also announced that it has developed a 60 Ah SCiB cell targeted for large-scale stationary energy storage systems (e.g., for solar) and for electric vehicles. The cell is to begin production this year.

The newly developed cell features volumetric energy density of about 230 – 270 Wh/L.

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=> Toshiba To Develop EV Batteries With Fiat, Scania; New 60 Ah Cell.

New Lithium Iron Pyrophosphate as Li-ion Cathode Material; Highest Voltage Among Known Iron-based Phosphate Cathodes

A team from the University of Tokyo and the Tokyo Institute of Technology has synthesized a new pyrophosphate compound (Li₂FeP₂O₇) by a conventional solid-state reaction for use as a cathode material in Li-ion batteries. Reversible electrode operation at ca. 3.5 V vs. Li was identified with the capacity of a one-electron theoretical value of 110 mAh g^-1 even for ca. 1 µm particles without any special efforts such as nanosizing or carbon coating.

The new pyrophosphate Li₂FeP₂O₇ thus offers the highest voltage among the known Fe-based phosphate cathodes, they noted in a Communication in the Journal of the American Chemical Society.

The material showed steady capacity retention upon cycling. However, they found, the initial charge curve showed a different shape from that of subsequent cycles, possibly due to the irreversible structural change. About 40% of the initial capacity can be delivered in 1 h (1C rate), and about 20% even in 6 min (10C rate), suggesting that such electrodes could sustain respectable rate capabilities, they observed.

Li₂FeP₂O₇ and its derivatives should provide a new platform for related lithium battery electrode research and could be potential competitors to commercial olivine LiFePO₄, which has been recognized as the most promising positive cathode for a lithium-ion battery system for large-scale applications, such as plug-in hybrid electric vehicles.

—Nishimura et al.

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=> New Lithium Iron Pyrophosphate as Li-ion Cathode Material; Highest Voltage Among Known Iron-based Phosphate Cathodes.

NASA Awards Contract to NEI and UCSD to Develop Nanoscale Materials for High Energy Density Li-ion Batteries

NASA has awarded a Phase II Small Business Technology Transfer (STTR) contract to NEI Corporation and the University of California, San Diego (UCSD) to develop and implement high energy density cathode materials for Li-ion batteries. NEI is the prime contractor and UC San Diego is the subcontractor. NEI expects sample cathode materials for testing by interested end-users to be made available by the middle of 2011.

The outcome of the program will be a commercially useable cathode material with a high capacity of more than 250 mAh/g, which translates to an energy density in excess of 1000 Wh/kg. This represents a factor of two enhancement in energy density over lithium cobalt oxide.

NASA says that such advanced lithium-ion battery systems are required for its exploration missions that will operate at low temperatures and could be used to power components and systems such as the James Webb Space Telescope (JWST), Mars Atmospheric and Volatile Evolution (MAVEN), deep drilling equipment and Astrobiology Field Laboratory on Mars, International X-ray Observatory (IXO), and extravehicular activities. Additionally, the lithium-ion battery packs could also be used in hybrid electric vehicles, consumer electronics, medical devices, electric scooters, and a variety of military applications.

The nearly $600,000 program builds upon expertise in the Department of NanoEngineering at UC San Diego in modeling new nanocomposite structures for next generation electrode materials, and NEI’s capability to reproducibly synthesize electrode materials, particularly at the nanoscale. NEI says it has overcome the challenge of producing ultrafine powders that can be used in the fabrication of electrodes without any further processing, i.e., it is a drop-in replacement for conventionally used materials.

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=> NASA Awards Contract to NEI and UCSD to Develop Nanoscale Materials for High Energy Density Li-ion Batteries.

Ultrathin LiMn2O4 Nanowire Cathode Materials for Higher Li-ion Power Densities for HEV and EV Applications

A team of researchers from the Korea Advanced Institute of Science and Technology, Università degli Studi di Milano-Bicocca (Italy), and Stanford University have synthesized ultrathin LiMn₂O₄ nanowires for use as a Li-ion cathode material offering high power densities.

Galvanostatic battery testing showed that the ultrathin LiMn₂O₄ nanowires deliver 100 and 78 mAh/g at very high rate (60C and 150C, respectively) in a larger potential window with very good capacity retention and outstanding structural stability. Such performances are due to both the favorable morphology and the high crystallinity of nanowires, the researchers said in a paper published online 26 August in the ACS journal NanoLetters.

Although lithium ion batteries can provide higher energy density (W h/kg) than other secondary systems, they have limited power density (W/kg) compared to double layer and pseudocapacitors. Hence the improvement of the specific power density in lithium ion batteries is a fundamental issue to develop better HEVs and EVs. Spinel LiMn₂O₄ is a promising candidate to replace layered Ni or Co oxide materials as cathode in lithium ion batteries because of its intrinsic low-cost, environmental friendliness, high abundance, and better safety.

However, the application of LiMn₂O₄ in high power systems requires the development of fast kinetic electrodes which appears nowadays possible thanks to the use of nanostructured morphologies…we believe ultrathin nanowire LiMn₂O₄ is a promising cathode material for lithium ion batteries for HEV and EV applications thanks to its high rate capability and superior structural stability.

—Lee et al.

The researchers had earlier shown that one-dimensional nanosized materials have faster kinetics and higher rate capability than micrometer-sized materials due to the large surface-to-volume ratio that enhances the contact between active material grains and electrolyte. LiMn₂O₄ nanorods with 150 nm diameter showed good capacity retention (around 60%) up to 5C.

In the current paper, they synthesized the ultrathin spinel nanowires using a two-step process: a solvothermal reaction to prepare α-MnO₂ nanowires followed by solid state reaction with LiOH.

The team used a coin-type cell configuration to evaluate the electrochemical properties of the nanowire materials as cathode electrodes. When charged at 1C the electrode shows a discharge specific capacity of about 90 mAh/g at 20C between 3.1 and 4.3 V vs Li. When the cycling potential range is enlarged to overcome electrode kinetic limitations, nanowires are able to deliver “relevant discharge capacities” (around 80 mAh/g) even at an extremely high current density (22.2 A/g, 150C rate), with high reversibility and good capacity retention, they found.

As produced LiMn₂O₄ nanowires have around 10 nm diameter, and they are several micrometers in length. Such morphology improves the kinetic properties at very high current rate and was capable of the facile structural transformation of the cubic and tetragonal phase in the large compositional range.

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=> Ultrathin LiMn2O4 Nanowire Cathode Materials for Higher Li-ion Power Densities for HEV and EV Applications.

Sony Develops 1.2 kWh Li-ion Module for Stationary Applications; Olivine-type Lithium Iron Phosphate

Sony has developed an energy storage module using lithium-ion rechargeable batteries made with olivine-type lithium iron phosphate as the cathode material. Key features of olivine-type lithium iron phosphate cell include high power output, long-life performance and excellent thermal stability. Sample shipments of the new module are scheduled to begin from June, 2010.

The new Sony Li-ion 1.2 kWh module. Click to enlarge.

The newly-developed module offers 1.2 kWh capacity. Multiple modules can be connected either in series or in parallel to expand to a higher voltage or capacity.

Each module is compatible with a high power output maximum of up to 2.5 kW, and can be used for various stationary power supplies such as UPS (uninterruptible power supply) for data servers or as a backup power supply for mobile phone wireless base stations.

Quick Specs
Capacity: 1.2kWh Nominal voltage: 51.2V Maximum output: 2.5kW Dimensions: 431 x 420 x 79mm Weight: approx. 17kg

Internal battery usage can be controlled safely by monitoring the state (voltage, current, temperature) of the internal batteries and communicating this to a linked external battery management system.

Sony estimates a 10-year useful life for the module with one charge-discharge cycle per day.

This energy storage module will be on display at the China International Battery Fair 2010 (held from 24-26 June 2010) in Shenzhen.

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=> Sony Develops 1.2 kWh Li-ion Module for Stationary Applications; Olivine-type Lithium Iron Phosphate.

Battery Researcher Suggests Achieving Next-Generation Battery Technology Will Require Interdisciplinary Approaches; A Doubling of Li-ion Capacity Over Next 30 Years

In a review of the challenges facing Li-ion battery development published in an open access paper in Philosophical Transactions of the Royal Society A, materials scientist Dr. Jean-Marie Tarascon of the Laboratoire réactivité et chimie des solides (LRCS) at Université de Picardie Jules Verne, CNRS proposes a two-fold increase in energy density over the next 30 years, most likely coming from the Li–air system.

For applications from which cost and materials resources are crucial, organic Li-ion and Na-ion will play an important role in the years to come, he also projects. These predictions, he cautions, do not take into account “complete out-of-the box solutions to electrochemically store electricity, but some of the concepts related to the latter are hopefully maturing in a few laboratories.”

Although currently at Université de Picardie Jules Verne, Tarascon spent most of his career in the US, including at Bell Laboratory and Bellcore up to 1994. At the beginning of the 90s, Bellcore asked him to create a new group on energy storage, which was rapidly prolific with, in particular, the optimization of new organic electrolytes for high voltage electrodes thus allowing the achievement of the LiMn₂O₄/C Li-ion battery or the discovery of the plastic Li-ion battery (PLiON), which is now commercialized.

Dr. Tarascon says that the most important results to which he contributed are the stabilization of the LiMn₂O₄-electrolyte interface; the design of an electrochromic system resting only on the presence of electrochemically active species in solution; the pioneering role of the LRCS in the contribution of mechanical grinding to the performances optimization of the electrode materials for Li-ion batteries; and the discovery of a new reversible Li reaction mechanism in highly divided mediums.

In the paper, Tarascon notes that:

…we should be aware that a colossal task is awaiting us if we really want to compete with gasoline, as an increase by a factor of 15 is needed for the energy delivered by a battery (180 Wh kg^-1) to match the one of a litre of gasoline (3000 Wh l^-1; taking into account corrections from Carnot’s principle). Knowing that the energy density of batteries has only increased by a factor of five over the last two centuries, our chances to have a 10-fold increase over the next few years are very slim, with the exception of unexpected research breakthroughs.

Nevertheless, he writes, “there is room for optimism as long as we pursue paradigm shifts while keeping in mind the concept of materials sustainability”, such as new ways to prepare electrode materials via eco-efficient processes or the use of organic rather than inorganic materials or new chemistries. Achieving these concepts will require the inputs of multiple disciplines, Tarascon emphasizes.

The chances of drastically improving current Li-ion cell energy density are mainly rooted in cathode materials that could either display greater redox potentials (e.g. highly oxidizing) or larger capacity (materials capable of reversibly inserting more than one electron per 3d metal).

In the long term, improving the Li-ion technology while preserving its sustainable aspect will require out-of-the-box solutions. Metal–air systems (Zn–air, Al–air and more so Li–air) have long been recognized as great candidates for achieving staggering energy-density increases. However, despite the efforts that went into these technologies, very little progress has been made regarding their reversibility so that they rapidly fell into oblivion.

Using the most attractive Li–air system as a reversible battery must at least clear three scientific/technological hurdles: (i) designing efficient oxygen electrodes knowing that confectioning such electrodes has been a nightmare for fuel cells, (ii) ensuring the development of electrode formulations that are capable of solvating oxygen and are stable with respect to the superoxide anions, and (iii) mastering the Li–electrolyte interface that we could not solve for the last 25 years within the field of Li batteries, the reason why the presently successful Li-ion battery technology has surfaced in the first place. Solving all of these at once is a colossal task that will require several years of cooperative research.

Despite that, Tarascon notes, there is reason for optimism given the increasing number of groups becoming involved with the Li–air system. Tarascon also cited Li-Sulfur (Li-S) as a promising system. Overall, Li–air and Li–S technologies beneficially share the same problems, he writes, as any advance in Li–air can be directly implemented in Li–S and vice versa. Their penetration into the market is a few years ahead, with Li-S most likely being the first one, he predicts.

The implementation of electrodes, enlisting raw abundant elements made via eco-efficient processes or obeying the renewable concept with zero carbon footprint, together with recent advances in sustainable and green Li–air systems, is shaping a bright future for electrochemical storage over the years to come…Regardless of the fact that future predictions are very hard, it is a certainty that sustainable and greener Li-based storage technologies will no longer be science fiction in the years to come. Achieving such a next generation of storage technologies will eagerly require interdisciplinary approaches, and our success will depend on how good we are in setting cross-fertilization between these different disciplines.

Addressing energy-related issues is a worldwide problem shared by many countries. Nevertheless, while targeting similar objectives and having similar road maps, various countries have tendencies to favour national over worldwide programmes. Time is limited, and it is urgent for our politics to find means/infrastructures to enhance the cross sharing of information between national programmes dealing with energy-related matters, both at the European and international levels. Concrete actions must be rapidly taken if we want to secure a bright future for the generations to come and to our planet as a whole.

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=> Battery Researcher Suggests Achieving Next-Generation Battery Technology Will Require Interdisciplinary Approaches; A Doubling of Li-ion Capacity Over Next 30 Years.

MIT Lithium-Air Battery Achieves New Record Efficiency

A catalyst developed by researchers at MIT makes rechargeable lithium-air batteries significantly more efficient–a step toward making these high-energy-density batteries practical for use in electric vehicles and elsewhere.

Air catalyst: Gold and platinum alloy nanoparticles (the dark areas) sit on top of a carbon black substrate (the lighter patterns); together, these materials improve the efficiency of lithium-air batteries. Credit: Yi-Chun Lu

The catalyst consists of nanoparticles of a gold and platinum alloy; in testing it was able to return 77 percent of the energy used to charge the battery as electricity when discharged. That’s up from the previously published record of about 70 percent, the researchers say. The work, which was reported online this week in the Journal of the American Chemical Society, suggests a new approach to lithium-air battery catalysts that could lead to the even higher efficiencies of 85 to 90 percent needed for commercial batteries.

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=> MIT Lithium-Air Battery Achieves New Record Efficiency.

Nissan May Not be Talking, But Others are Spilling the Beans on the LEAF Battery Price

Last week it surfaced that the Nissan LEAF battery may cost an astoundingly low $375 per kilowatt hour to produce. Given that the battery is the single most expensive piece of equipment on electric cars, getting that cost down as quickly as possible will be key to selling them at reasonable prices.

In a Bloomberg report today, the LEAF’s battery maker, Automotive Energy Supply Corporation (AESC) — which is joint venture between Nissan and NEC — is saying that their targets are “a lot tougher.” Masahiko Otsuka, president of AESC, even went on to give specifics, saying that their target is lower than $370 per kWh for the entire battery pack.

Whether or not that price is what AESC can provide out of the starting gate is another question entirely.

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=> Nissan May Not be Talking, But Others are Spilling the Beans on the LEAF Battery Price.

CFX Battery Changes Name to Contour Energy Systems, Entering Market with High Power Lithium Carbon Flouride Primary Batteries; Next-Generation Secondary Batteries Under Development

Comparison of gravimetric and volumetric energy densities for four different types of 2016 coin cells. The Li/CFx battery affords a significant improvement over both primary lithium and alkaline batteries. Source: Contour. Click to enlarge.

Contour Energy Systems, a spinoff of the collaboration between CalTech and CNRS, the French National Center for Scientific Research, is emerging from stealth mode with advancements in new fluorine-based battery chemistries, nanomaterials science and manufacturing processes for lithium-ion energy storage systems. The company was formerly known as CFX Battery.

The company plans initially to commercialize advanced primary battery systems in multiple form factors (coin, cell, film or prismatic), targeting a wide range of portable power applications spanning the transportation, government and defense, medical, industrial, portable electronics and specialty application markets. The company is targeting an accelerated time-to-market for next-generation rechargeable (secondary) batteries that will also benefit from its battery chemistries and materials.

Li/CFx
3 V system CFx stable and inert up to 400 °C Highest theoretical energy density (~2180 Wh/kg) among primary lithium systems

Carbon fluoride batteries have been around since the 1970s, featuring high energy density, high temperature performance, and shelf life. However, they have suffered from limited power capability and reduced low temperature performance. Contour developed a proprietary process that introduces fluorine into the carbon material that provides a fundamentally different atomic structure than traditional carbon fluoride materials to address those limitations.

This new structure, coupled with the use of new materials, retains all the favorable aspects of traditional primary Li/CF_x batteries, while providing best-in- class power and low temperature performance versus other lithium primary-based systems.

Contour Energy’s fluoride chemistry can be customized during key steps in the manufacturing process to alter the cathode’s physical structure at the atomic level. This “Tunable Cathode”, combined with a novel anode, electrolyte and/or separator materials enables application-specific batteries featuring an optimal combination of higher energy and/or power densities, and discharge rates, according to the company. Improvements over existing primary lithium batteries include:

• Up to 3X increase in energy density (>700 Wh/Kg)
• Up to 8X increase in power density
• Operation from -60°C to in excess of 160°C
• A shelf life of up to 15 Years
• No overheating or passivation
• No heavy metals or toxic chemicals

NASA contracts. The National Aeronautics and Space Administration (NASA) has awarded the company two technology transfer contracts. With the first contract, NASA is engaging Contour Energy to develop high-energy primary batteries with advanced safety features capable of performing under a wide temperature range for manned space missions. To meet this goal, Contour Energy will characterize and establish the technological feasibility of a new lithium carbon-fluoride-based high capacity primary battery that offers higher rate capabilities and enhanced safety characteristics compared to conventional Li/CFx primary systems.

Potential NASA commercial applications resulting from Contour Energy’s technology transfer contract include advanced primary lithium carbon fluoride battery systems that can be used for exploratory missions including power to support outposts, habitats, and science packages. The high specific energy will greatly reduce the mass of the batteries used onboard in long distance space missions.

The second NASA technology transfer contract engages Contour Energy to pursue the chemical conversion of micron-sized, nano-structured templates available from renewable resources into functional electrode materials. The objective is to establish that electrodes fabricated from these nanostructures are innovative materials providing improved electrochemical performance compared to traditional electrodes.

By achieving this goal, Contour Energy will be positioned to address the significant increases in energy capacity, power capability and cycling stability necessary to meet the NASA requirements for advanced Li-ion battery technology. Key NASA applications that can take advantage of such innovative rechargeable cell chemistries and advanced electrode materials include power sources for Landers, Rovers and extra-vehicular activities.

Co-founders of Contour Energy are Dr. Robert Grubbs, 2005 Nobel Laureate, Professor of Chemistry at CalTech, and founder of several other high technology materials companies; Dr. Rachid Yazami, a visiting professor from Cal Tech; and Dr. Andre Hamwi, Professor at the University of Blaise-Pascal, Clermont-Ferrands, France with more than 30 years of electrochemistry experience, holder of more than 30 patents, and a recognized specialist in fluorine. Drs. Grubbs and Hamwi are serving as company advisors, and Dr. Grubbs sits on the Board of Directors.

Headquartered in Azusa, CA, Contour Energy is managed by a team of battery industry leaders from CalTech, Energizer, Duracell, ConocoPhillips, Hewlett-Packard and Ultralife. The company is privately held with funding from CMEA Capital, Harris and Harris, Schlumberger and US Venture Partners.

Resources

• J. F. Whitacre, W. C. West, M. C. Smart, R. Yazami, G. K. Surya Prakash, A. Hamwi and B. V. Ratnakumara (2007) Enhanced Low-Temperature Performance of Li–CF_x Batteries. Electrochemical and Solid-State Letters, 10 (7) A166-A170 doi: 10.1149/1.2735823

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=> CFX Battery Changes Name to Contour Energy Systems, Entering Market with High Power Lithium Carbon Flouride Primary Batteries; Next-Generation Secondary Batteries Under Development.

New Self-Assembled Silicon-Carbon Nanocomposite Anodes for Li-ion Batteries Offer More Than 5X The Reversible Capacity of Graphite Anodes

This scanning electron micrograph shows carbon-coated silicon nanoparticles on the surface of the composite granules used to form the new anode. Source: Georgia Tech. Click to enlarge.

Researchers have developed a new high-performance anode structure for lithium-ion batteries based on silicon-carbon nanocomposite materials. Produced via large-scale hierarchical bottom-up assembly, the material contains rigid and robust silicon spheres with irregular channels for rapid access of Li ions into the particle bulk.

The large silicon volume changes on lithium ion insertion and extraction—which can cause structural problems leading to rapid capacity loss—are accommodated by the particle’s internal porosity. The researchers have shown reversible capacities more than five times higher than that of the state-of-the-art graphite anodes (1,950 mAh g^-1) and stable performance. The synthesis process is simple, low-cost, safe and broadly applicable, they say, providing new avenues for the rational engineering of electrode materials with enhanced conductivity and power.

Details of the new self-assembly approach were published online in the journal Nature Materials on 14 March.

Development of a novel approach to producing hierarchical anode or cathode particles with controlled properties opens the door to many new directions for lithium-ion battery technology. This is a significant step toward commercial production of silicon-based anode materials for lithium-ion batteries.

—Gleb Yushin, an assistant professor in the School of Materials Science and Engineering at the Georgia Institute of Technology

Fabrication of the composite anode begins with formation of highly conductive branching structures made from carbon black nanoparticles annealed in a high-temperature tube furnace. Silicon nanospheres with diameters of less than 30 nanometers are then formed within the carbon structures using a chemical vapor deposition process. The silicon-carbon composite structures resemble “apples hanging on a tree.”

Using graphitic carbon as an electrically-conductive binder, the silicon-carbon composites are then self-assembled into rigid spheres that have open, interconnected internal pore channels. The spheres, formed in sizes ranging from 10 to 30 microns, are used to form battery anodes. The relatively large composite powder size—a thousand times larger than individual silicon nanoparticles—allows easy powder processing for anode fabrication.

Proposed schematic for the formation of bulk Si-C nanocomposite electrodes via hierarchical bottom-up assembly. (a) annealed carbon black dendritic particles are (b), coated by Si nanoparticles; (c) composite particles are mixed with a sacrificial binder and compacted into an electrode with open interconnected internal channels. The electrode is then transformed into a solid bulk electrode during annealing. Such electrodes will not require polymeric binders and may exhibit enhanced stability, higher electrical conductivity and larger volumetric capacity. Source: Magasinki et al., Supplementary materials. Click to enlarge.

The internal channels in the silicon-carbon spheres serve two purposes. They admit liquid electrolyte to allow rapid entry of lithium ions for quick battery charging, and they provide space to accommodate expansion and contraction of the silicon without cracking the anode. The internal channels and nanometer-scale particles also provide short lithium diffusion paths into the anode, boosting battery power characteristics.

The size of the silicon particles is controlled by the duration of the chemical vapor deposition process and the pressure applied to the deposition system. The size of the carbon nanostructure branches and the size of the silicon spheres determine the pore size in the composite.

Production of the silicon-carbon composites could be scaled up as a continuous process amenable to ultra high-volume powder manufacturing, Yushin said. Because the final composite spheres are relatively large when they are fabricated into anodes, the self-assembly technique avoids the potential health risks of handling nanoscale powders, he added.

So far, the researchers have tested the new anode through more than a hundred charge-discharge cycles. Yushin believes the material would remain stable for thousands of cycles because no degradation mechanisms have become apparent.

In addition to Yushin, the paper’s authors included Alexandre Magasinki, Patrick Dixon and Benjamin Hertzberg—all from Georgia Tech—and Alexander Kvit from the Materials Science Center and Materials Science Department at the University of Wisconsin-Madison, and Jorge Ayala from Superior Graphite. The paper also acknowledges the contributions of Alexander Alexeev at Georgia Tech and Igor Luzinov from Clemson University.

The research was partially supported by a Small Business Innovation Research (SBIR) grant from the National Aeronautics and Space Administration (NASA) to Chicago-based Superior Graphite and Atlanta-based Streamline Nanotechnologies, Inc.

Resources

• A. Magasinki, P. Dixon, B. Hertzberg, A. Kvit, J. Ayala, G. Yushin (2010) High-performance lithium-ion anodes using a hierarchical bottom-up approach. Nature Materials doi: 10.1038/nmat2725

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=> New Self-Assembled Silicon-Carbon Nanocomposite Anodes for Li-ion Batteries Offer More Than 5X The Reversible Capacity of Graphite Anodes.

Electric Car Battery Prices Dropping Much Faster than Expected

One of the biggest barriers to the adoption of electric cars, plug-in hybrids and extended range electric vehicles is cost. The biggest part of that added cost is the battery. In the past, estimates of roughly $1000 per kWh of battery capacity have been thrown around as a way to gauge how much of a premium consumers can expect to pay. Given that it takes roughly 25 kWh to go 100 miles, you can see how this would quickly add up.

Recently, however, the cost of lithium-ion batteries has been dropping more steeply than expected; indicating that the potential in the market to reduce the premium of owning a battery-powered car has been greatly underestimated.

Gas 2.0

=> Electric Car Battery Prices Dropping Much Faster than Expected.

Idemitsu Kosan Developing Phosphorous Sulfide Solid Electrolyte for Lithium-ion Batteries

Idemitsu Kosan Co. Ltd., is developing a phosphorous sulfide solid electrolyte (Li₂S-P₂S₅) for solid-state lithium-ion batteries. The company expects to commercialize solid-state lithium-ion cells using the new electrolyte around 2012.

Idemitsu is a petroleum and petrochemical company, and identified the potential of lithium sulfide as an electrolyte material for rechargeable Li-ion batteries (secondary batteries) when evaluating the uses of high-purity lithium sulfide produced for the PPS resin process. In 2006, the company announced that it was accelerating development of the solid electrolyte based on its belief that the material would be “highly suitable” for hybrid and electric vehicles, and said that the electrolyte under development possessed a lithium-ion conductivity of 4×10^-3S/cm at room temperature—equivalent to the liquid organic electrolyte currently used in lithium-ion secondary batteries.

MRS 2010 Spring Meeting
At the upcoming MRS 2010 Spring Meeting in San Francisco (5-9 April 2010), Yoshikatsu Seino from Idemitsu Kosan is presenting an invited paper on the high rate capability of all-solid state batteries using the phosphorous sulfide solid electrolyte.

Unlike liquid organic electrolytes, however, the solid electrolyte possesses excellent stability thanks to its resistance to degradation or vaporization even at high voltages and temperatures. A solid electrolyte avoids safety hazards such as solvent leakage and flammability, and also offers the advantage of a wide variety of construction techniques. A battery using the solid electrolyte under development by Idemitsu also operated at low temperatures of less than 0 °C.

The phosphorous sulfide electrolyte can be used with a variety of electrode materials. At the 214^th meeting of the Electrochemical Society (ECS) in October 2008, for example, researchers from Idemitsu presented a paper showing the use of the lithium sulfide electrolyte with lithium anodes.

Idemitsu also suggests that the use of the lithium sulfide electrolyte would enable the use of a sulfur material—which electrochemically has a high capacity—in the cathode.

[In February, a team led by Dr. Yi Cui at Stanford University reported the demonstration of a new proof-of-concept lithium metal-free battery with high specific energy consisting of a lithium sulfide (Li₂S)/mesoporous carbon composite cathode and a silicon (Si) nanowire anode. (Earlier post.) At the upcoming 217^th meeting of the ECS, a research group from the University of Colorado, Boulder, will present a paper on the use of nanosilicon as an anode material in all solid-state batteries with a Li₂S-P₂S₅-based solid electrolyte.]

At the 1^st International Rechargeable Battery Expo in Tokyo last week, Idemitsu exhibited an A6-size (105 mm × 148 mm) laminated solid-state lithium-ion (Li-ion) battery using its lithium sulfide electrolyte.

With cells connected in series, the A6-size battery has an output voltage of 14-16V and a solid electrolyte membrane with a thickness of about 100 µm. Idemitsu did not disclose its power and energy densities.

Idemitsu Kosan said it will further the thickness of the electrolyte membrane to 10-20 µm to lower the resistance and search for an optimal electrode material.

Resources

• T. Utaka, Y. Seino, Y. Saito (2008) All-solid-state lithium batteries with sulfide-based solid electrolytes and lithium negative electrodes. (ECS 214)
• James Trevey, Conrad Stoldt, and Se-Hee Lee (2010) All-Solid-State Rechargeable Lithium-Ion Batteries with Li2S-P₂S₅ Based Electrolytes (ECS 217)

Green Car Congress

=> Idemitsu Kosan Developing Phosphorous Sulfide Solid Electrolyte for Lithium-ion Batteries; Commercialization of Solid-State Battery Targeted for 2012.

Li-ion Manufacturer Boston-Power Names Former GM Senior Executive Bob Purcell to Board; Expansion Into Transportation With a Focus on PHEVs and BEVs

In the transportation sector, Boston-Power is targeting its high-energy, long-life cells at plug-in hybrid and full battery electric vehicles. Click to enlarge.

Li-ion manufacturer Boston-Power, Inc., announced that former GM executive Robert C. Purcell, Jr. has joined its board of directors. Working closely with Boston-Power’s executive team and fellow board members, Purcell is applying his expertise in battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs) to help drive the deployment of Boston-Power’s batteries into the transportation sector.

From 1994 to 2002, Purcell led the GM Advanced Technology Vehicles Group (GM ATV). GM ATV was responsible for the development and production of the GM EV-1; his organization also developed and produced the S-10 Electric Truck and developed the GM Precept Hybrid Vehicle, which was part of President Clinton’s Partnership for a New Generation of Vehicles (PNGV) program. In addition to his responsibilities at GM ATV, he also served as chairman of the GM-Ovonic Advanced Battery Joint Venture.

Purcell currently serves as founder and president of Purcell & Associates, LLC, a senior advisory group specializing in advanced automotive and alternative energy investment projects. His clients have included companies ranging from MidAmerican Energy Holdings, a Berkshire Hathaway Company, to EDC Automotive, an emerging leader in automotive thermal management systems.

Boston-Power is bringing to the transportation industry a game-changing lithium-ion battery that delivers unmatched levels of high energy density, safety, low cost, fast charge and environmental sustainability. As a pioneer in the electrification of transportation, Bob Purcell brings a perfect combination of invaluable insights, real-world experiences, and an established, international executive network to our company. We’re thrilled to add him to our team.

—Boston-Power Founder and CEO Dr. Christina Lampe-Onnerud

I’ve been looking for a battery like Boston-Power’s for 20 years. I knew immediately upon meeting the team and reviewing the technology platform that I wanted to play a role within the company. In addition to being in mass production and embodying the right combination of capabilities in terms of extended range, weight and space, safety, cost and quick recharge, Boston-Power’s batteries are the only ones to earn stringent certifications for environmental sustainability. They’re already being well received by the auto industry and I’m confident they will be adopted for a range of vehicles by manufacturers around the world.

—Bob Purcell

Boston-Power is focused on delivering the high energy density and long deep discharge cycle life that it says are critical for the continued evolution towards higher degrees of hybridization and BEVs. Click to enlarge.

Boston-Power technology. Boston-Power’s battery technology platform is based on a flat, oval-shaped prismatic cell design with external dimensions equivalent to two conventional 18650 lithium-ion cells. Boston-Power currently uses cobalt and manganese on the cathode with graphite on the anode. Each cell incorporates multiple, independent safety devices located in different areas of the cell. The design of each safety component is optimized independent of the other components, and the distributed location eliminates unwanted interactions between them.

One of the safety devices is the integrated Current Interrupt Device (CID), which electrically disconnects the cell if internal pressures get too high. In addition, the cell can is constructed from aluminum, supporting a low pressure design which allows safety components to activate earlier, minimizing the chance that the cell will enter thermal runaway. The activation pressure and tolerances of each of the components are designed to prevent inadvertent activation. In addition, there are two vents on the side of the can for redundancy, minimizing the chance of cascading failures in a multi-cell pack.

The company has so far introduced two products from this platform:

Sonata cycle life. Click to enlarge.

• Sonata cells for notebook and portable power applications. The Sonata cells offer 3x – 5x longer battery service life than competitors in this market. In March 2009, Boston-Power became the first US-based firm to provide batteries to a Tier One notebook PC vendor: HP.
• Swing cells for electric vehicle, industrial and electronic applications. (Earlier post.) Some of the attributes of the Swing 4400 include:
  • Energy density of 180Wh/kg
  • Volumetric density of 420Wh/L
  • 1,000+ cycles at 100% Depth Of Discharge (DOD)
  • 2,000+ cycles at 90% DOD
  • Constant power of 440W/kg
  • Pulse power of 1,500 W/kg (2s pulse)
  • Flexible and scalable packaging
  • Excellent thermal properties
  • Nordic Ecolabel and Chinese EPA CEC Ecolabel accreditation for chemical control during manufacturing and in the final product
  • UL, UN, and ROHS certifications

Boston Power Swing 12 kWh Escape PHEV Demonstrator
Number of cells: 792 (88s9p) Number of modules: 11 Module rating: 1.1 kWh Voltage: 340V Capacity: 39.6 Ah Cell Equalization (balancing) Cooling: Convection air

Boston-Power intends to leverage its experience from the Portable Power industry into Transportation. Boston-Power cells are in mass production today in its manufacturing facilities in Asia, with the capacity to scale to millions of cells per month. (The company says it has had zero field failures so far.)

In 2009, Boston-Power developed a Ford Escape plug-in demonstrator equipped with a 12 kWh pack. In December 2009, the company became part of a Swedish electric automobile coalition established to drive the advancement of high performance electric vehicles. (Earlier post.) In addition to Boston-Power, participating organizations include Saab; Electroengine (electric powertrain); Innovatum (project management); and Power Circle (Sweden’s electric power industry trade organization).

Prior to the announcement of his appointment, Purcell told Green Car Congress that while many of the OEMs have selected the source for their first program, few of them are fixed—Toyota being at least one notable exception—in terms of strategic battery supply.

What I am doing is providing a set of introductions to the right people around the industry who are interested in looking at alternative batteries. What I like about Boston-Power…I really believe they made the best set of tradeoffs in terms of the battery systems. It is high energy density in terms of the basic chemistry of the battery, they have packaged it in a way that they can leverage the volume base they have already created in terms of portable power. They have done an outstanding job, in my opinion, in safety design…They have the best chance of actually surviving the automotive application for the lifecycle of the vehicle.

Green Car Congress

=> Li-ion Manufacturer Boston-Power Names Former GM Senior Executive Bob Purcell to Board; Expansion Into Transportation With a Focus on PHEVs and BEVs.