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  • richardmitnick 8:49 am on August 6, 2014 Permalink | Reply
    Tags: , Battery technology, ,   

    From Brookhaven Lab: “New Method Provides Nanoscale Details of Electrochemical Reactions in Electric Vehicle Battery Materials” 

    Brookhaven Lab

    August 4, 2014
    Karen McNulty Walsh, (631) 344-8350 or Peter Genzer, (631) 344-3174

    Using a new method to track the electrochemical reactions in a common electric vehicle battery material under operating conditions, scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have revealed new insight into why fast charging inhibits this material’s performance. The study also provides the first direct experimental evidence to support a particular model of the electrochemical reaction. The results, published August 4, 2014, in Nature Communications, could provide guidance to inform battery makers’ efforts to optimize materials for faster-charging batteries with higher capacity.

    three
    Jiajun Wang, Karen Chen and Jun Wang prepare a sample for study at NSLS beamline X8C.

    “This is the first time anyone has been able to see that delithiation was happening differently at different spatial locations on an electrode under rapid charging conditions.”
    — Brookhaven physicist Jun Wang

    “Our work was focused on developing a method to track structural and electrochemical changes at the nanoscale as the battery material was charging,” said Brookhaven physicist Jun Wang, who led the research. Her group was particularly interested in chemically mapping what happens in lithium iron phosphate—a material commonly used in the cathode, or positive electrode, of electrical vehicle batteries—as the battery charged. “We wanted to catch and monitor the phase transformation that takes place in the cathode as lithium ions move from the cathode to the anode,” she said.

    Getting as many lithium ions as possible to move from cathode to anode through this process, known as delithiation, is the key to recharging the battery to its fullest capacity so it will be able to provide power for the longest possible period of time. Understanding the subtle details of why that doesn’t always happen could ultimately lead to ways to improve battery performance, enabling electric vehicles to travel farther before needing to be recharged.

    X-ray imaging and chemical fingerprinting

    mapping
    In operando 2D chemical mapping of multi particle lithium iron phosphate cathode during fast charging (top to bottom). The called-out close-up frame shows that as the sample charges, some regions become completely delithiated (green) while others remain completely lithiated (red). This inhomogeneity results in a lower overall battery capacity than can be attained with slower charging, where delithiation occurs more evenly throughout the electrode. No image credit

    Many previous methods used to analyze such battery materials have produced data that average out effects over the entire electrode. These methods lack the spatial resolution needed for chemical mapping or nanoscale imaging, and are likely to overlook possible small-scale effects and local differences within the sample, Wang explained.

    To improve upon those methods, the Brookhaven team used a combination of full- field, nanoscale-resolution transmission x-ray microscopy (TXM) and x-ray absorption near-edge spectroscopy (XANES) at the National Synchrotron Light Source (NSLS), a DOE Office of Science User Facility that provides beams of high-intensity x-rays for studies in many areas of science. These x-rays can penetrate the material to produce both high-resolution images and spectroscopic data—a sort of electrochemical “fingerprint” that reveals, pixel by pixel, where lithium ions remain in the material, where they’ve been removed leaving only iron phosphate, and other potentially interesting electrochemical details.

    The scientists used these methods to analyze samples made up of multiple nanoscale particles in a real battery electrode under operating conditions (in operando). But because there can be a lot of overlap of particles in these samples, they also conducted the same in operando study using smaller amounts of electrode material than would be found in a typical battery. This allowed them to gain further insight into how the delithiation reaction proceeds within individual particles without overlap. They studied each system (multi-particle and individual particles) under two different charging scenarios—rapid (like you’d get at an electric vehicle recharging station), and slow (used when plugging in your vehicle at home overnight).

    Insight into why charging rate matters

    The detailed images and spectroscopic information reveal unprecedented insight into why fast charging reduces battery capacity. At the fast charging rate, the pixel-by-pixel images show that the transformation from lithiated to delithiated iron phosphate proceeds inhomogeneously. That is, in some regions of the electrode, all the lithium ions are removed leaving only iron phosphate behind, while particles in other areas show no change at all, retaining their lithium ions. Even in the “fully charged” state, some particles retain lithium and the electrode’s capacity is well below the maximum level.

    “This is the first time anyone has been able to see that delithiation was happening differently at different spatial locations on an electrode under rapid charging conditions,” Jun Wang said.

    Slower charging, in contrast, results in homogeneous delithiation, where lithium iron phosphate particles throughout the electrode gradually change over to pure iron phosphate—and the electrode has a higher capacity.

    Implications for better battery design

    Scientists have known for a while that slow charging is better for this material, “but people don’t want to charge slowly,” said Jiajun Wang, the lead author of the paper. “Instead, we want to know why fast charging gives lower capacity. Our results offer clues to explain why, and could give industry guidance to help them develop a future fast-charge/high-capacity battery,” he said.

    For example, the phase transformation may happen more efficiently in some parts of the electrode than others due to inconsistencies in the physical structure or composition of the electrode—for example, its thickness or how porous it is. “So rather than focusing only on the battery materials’ individual features, manufacturers might want to look at ways to prepare the electrode so that all parts of it are the same, so all particles can be involved in the reaction instead of just some,” he said.

    The individual-particle study also detected, for the first time, the coexistence of two distinct phases—lithiated iron phosphate and delithiated, or pure, iron phosphate—within single particles. This finding confirms one model of the delithiation phase transformation—namely that it proceeds from one phase to the other without the existence of an intermediate phase.

    “These discoveries provide the fundamental basis for the development of improved battery materials,” said Jun Wang. “In addition, this work demonstrates the unique capability of applying nanoscale imaging and spectroscopic techniques in understanding battery materials with a complex mechanism in real battery operational conditions.”

    The paper notes that this in operando approach could be applied in other fields, such as studies of fuel cells and catalysts, and in environmental and biological sciences.

    Future studies using these techniques at NSLS-II—which will produce x-rays 10,000 times brighter than those at NSLS—will have even greater resolution and provide deeper insight into the physical and electrochemical characteristics of these materials, thus making it possible for scientists to further elucidate how those properties affect performance.

    Yu-chen Karen Chen-Wiegart also contributed to this research. This work was supported by a Laboratory Directed Research and Development (LDRD) project at Brookhaven National Laboratory. The use of the NSLS was supported by the U.S. Department of Energy’s Office of Science.

    See the full article here.

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 11:28 am on July 28, 2014 Permalink | Reply
    Tags: , Battery technology, ,   

    From Brookhaven Lab: “Understanding the Source of Extra-large Capacities in Promising Li-ion Battery Electrodes” 

    Brookhaven Lab

    July 28, 2014
    Laura Mgrdichian

    Lithium (Li) ion batteries power almost all of the portable electronic devices that we use everyday, including smart phones, cameras, toys, and even electric cars. Researchers across the globe are working to find materials that will lead to safe, cheap, long-lasting, and powerful Li-ion batteries.

    Working at various U.S. Department of Energy light source facilities and at Cambridge and Stony Brook universities, a group of researchers recently studied a class of Li-ion battery electrodes that have capacities much greater than those of the materials used in today’s batteries. The researchers wanted to determine why these materials can often store more charge than theory predicts.

    path
    A summary of the three-stage reaction pathway of the ruthenium-oxide-lithium battery system.

    The authors chose ruthenium oxide (RuO2) as a model system to study these so-called “conversion materials,” named because they undergo large structural changes when reacting with lithium ions, reversibly forming metal nanoparticles and salts (here Ru and Li2O). These reactions are very different from those that occur in conventional electrodes, which store charge by allowing Li ions to nestle into spaces within the crystal lattice.

    “Our investigation identified the source of the additional capacity found for RuO2, and has also yielded a protocol for studying the ‘passivation layer’ that forms on battery electrodes, which protects the electrolyte from undergoing further decomposition reactions in subsequent charge-discharge cycles,” said the study’s corresponding researcher, Clare Grey, a professor in the chemistry departments at Cambridge and Stony Brook universities. “Understanding the structures of these passivation layers is key to making batteries that last long enough for use in applications such as transportation and power-grid storage.”

    At Brookhaven National Laboratory’s National Synchrotron Light Source, the team studied their samples using x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS). At the Advanced Photon Source at Argonne National Laboratory, they used two additional techniques, high-resolution x-ray diffraction (XRD) and scattering pair distribution function (PDF) analysis, to extract information on the electronic and long/short-range structural changes of the RuO2 electrode in real time as the battery was discharged and charged. Using these methods, the team showed that RuO2 was reduced to Ru nanoparticles and Li2O via the formation of intermediate phases, LixRuO2.

    Since this did not explain the source of the additional charge-storage mechanism, the group used another technique, high-resolution solid-state nuclear magnetic resonance (NMR). This method involves subjecting a sample to a magnetic field and measuring the response of the nuclei within the sample. It can yield specific information on the chemical compositions and local structures, and is particularly useful for studying compounds that contain only “light” elements, such as hydrogen (H), Li, and oxygen (O), which are difficult to detect using XRD. The NMR data showed that the major contributor to the capacity is the formation of LiOH, which reversibly converts to Li2O and LiH. Minor contributors to the capacity come from Li storage on the Ru nanoparticle surfaces, forming a LixRu alloy, and the decomposition of the electrolyte. The latter, however, ultimately causes the capacity to diminish and will result in the death of the battery following multiple charge cycles.

    Scientists from the University of Cambridge, Brookhaven National Laboratory, Argonne National Laboratory, and Stony Brook University conducted this research. It was published in the December 2013 issue of Nature Materials, 12, 1130-1136. The paper is titled Origin of additional capacities in metal oxide lithium-ion battery electrodes, and the authors are Yan-Yan Hu, Zigeng Liu, Kyung-Wan Nam, Olaf J. Borkiewicz, Jun Cheng, Xiao Hua, Matthew T. Dunstan, Xiqian Yu, Kamila M. Wiaderek, Lin-Shu Du, Karena W. Chapman, Peter J. Chupas, Xiao-Qing Yang and Clare P. Grey.

    See the full article here.

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 12:17 pm on July 7, 2014 Permalink | Reply
    Tags: , Battery technology, ,   

    From DOE Pulse: “Satisfying metals’ thirst vital for high-capacity batteries” 

    pulse

    See the full article here.

    July 7, 2014
    Kristin Manke, 509.372.6011,
    kristin.manke@pnnl.gov]

    Imagine a cell phone battery that worked for days between charges. At DOE’s Pacific Northwest National Laboratory, scientists are answering fundamental science questions that could make batteries work more efficiently. Replacing lithium, which is in the +1 oxidation state, with metals that can carry multiple charges could potentially increase battery capacity.

    PNNL Campus
    PNNL Campus

    “Our initial efforts focused on understanding the behavior of metals that have +2 or +3 oxidation states in an aqueous solution,” said Dr. Sotiris Xantheas, who led the research at PNNL. “This would double or triple the amount of charge that could be stored in a battery, but before this study, we had no insights on how the charge on the ions is either stabilized or destabilized when their local environment changes.”

    A roadblock to this future is understanding how to keep multiply charged ions stable with respect to hydrolysis channels.

    When a multiply charged ion, such as aluminum (Al+3), encounters a single water molecule, the result can be explosive. The metal ion rips an electron from the water molecule, causing a molecular-level explosion due to Coulombic forces. But multiply charged metal cations exist in water in countless ways, such as the calcium ions in your chocolate milkshake.

    The PNNL scientists, post-doctoral fellow Evangleos Miliordos and Laboratory Fellow Sotiris Xantheas, determined the paths that lead to either the hydrolysis of water or the creation of stable metal ion clusters peaceably surrounded by water. It comes down to the pH of the solution, the number of water molecules nearby and the energy needed to remove electrons from the metal, known as the ionization potential.

    This research was featured on the cover of Physical Chemistry Chemical Physics and in a special issue of Theoretical Chemistry Accounts dedicated to Prof. Thomas H. Dunning, Jr. on the occasion of his 70th birthday.

    “This paper describes an elegant use of computational modeling to understand a phenomena that is of fundamental importance in chemistry, yet has many practical applications as well,” said Dunning, co-director of the Northwest Institute for Advanced Computing, operated by PNNL and the University of Washington.

    What’s next? The researchers are now working to extend their computational protocol to the solution phase and at interfaces. Extending the methodology will allow the team to better understand the dynamic interactions occurring, eventually leading to better battery technologies.

    This research was sponsored by DOE’s Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division. Resources at the National Energy Research Scientific Computing Center were used.

    DOE Pulse highlights work being done at the Department of Energy’s national laboratories. DOE’s laboratories house world-class facilities where more than 30,000 scientists and engineers perform cutting-edge research spanning DOE’s science, energy, National security and environmental quality missions. DOE Pulse is distributed twice each month.

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  • richardmitnick 3:59 pm on May 22, 2014 Permalink | Reply
    Tags: , Battery technology, ,   

    From Brookhaven Lab: “MIT/National Labs Team Visualizes Complex Electronic State” 

    Brookhaven Lab

    May 21, 2014

    (The following news release was first issued by the Massachusetts Institute of Technology (MIT). The U.S. Department of Energy’s Brookhaven National Laboratory made crucial contributions to the research. Scientist Dong Su of the Center for Functional Nanomaterials (CFN) took scanning transmission electron microscopy (STEM) measurements of the samples and helped analyze the data, directly revealing the collective ordering and unexpected distortion of electrochemically inserted sodium. Physicists Jianming Bai of Photon Sciences and Feng Wang of Sustainable Energy Technologies performed x-ray diffraction experiments at the National Synchrotron Light Source (NSLS) that confirmed the results.)

    David L. Chandler | MIT News Office

    A material called sodium manganese dioxide has shown promise for use in electrodes in rechargeable batteries. Now a team of researchers has produced the first detailed visualization—down to the level of individual atoms—of exactly how the material behaves during charging and discharging, in the process elucidating an exotic molecular state that may help in understanding superconductivity.

    matter
    The internal molecular structure of the electrode compound reveals what the researchers call the “superstructure.” At right is a scanning transmission electron microscope image of the material, and, at left, the image is color-coded based on electrical properties: Each green dot stands for a stripe of manganese plus-4 ions; purple dots, for manganese plus-3 ions; and mixed color dots (green inside purple), for stripes with both ions. No image credit

    The new findings are reported this week in the journal Nature Materials, in a paper by MIT postdoc Xin Li, professors Young Lee and Gerbrand Ceder, also of MIT, and 12 others.

    The phenomenon the team investigated—known as the cooperative Jahn-Teller effect—“is a basic piece of physics that has been well-known historically,” explains Ceder, the R.P. Simmons Professor of Materials Science and Engineering. It describes how the positions of atoms in certain compounds can be slightly distorted, changing the material’s electrical and magnetic properties.

    “We began the electron microscopy work with MIT fellows about two years ago and combined our results with theoretical calculations to figure out the structure of NMO—it’s taken this long to run calculations and confirm those results with x-ray and neutron scattering so fantastically. Now, we’re finally ready for our findings to impact energy research and technology.”
    — CFN Scientist Dong Su

    “It is associated with a lot of interesting phenomena,” Ceder says—so a better understanding could be useful both in advancing our knowledge of physics and in potential applications, from improved batteries to new kinds of electronics.

    While the Jahn-Teller phenomenon is well known, Ceder says it’s a bit unusual to see it in battery compounds such as the sodium manganese dioxide now under investigation as a possible lower-cost substitute for the lithium-based electrodes in lithium-ion batteries.

    Such rechargeable batteries work when an electrical current pulls ions out of an electrode during charging, then returns them to the electrode as the battery is used. The arrangement of atoms within the material “is very ordered, and normally the ordering is driven by fairly standard physics,” Ceder says. “But in this material, the order is completely driven by the Jahn-Teller effect.”

    Understanding how that difference affects charging and discharging could be important in guiding teams around the world who are seeking to improve the performance of such batteries, but it proved a daunting challenge for the MIT team.

    The team combined density functional theory with technologies including electron diffraction; synchrotron X-ray diffraction; neutron diffraction; and aberration-corrected atomic-resolution scanning microscopy for direct visualization. Using these methods, the researchers showed that the material produces a “superstructure” governed by the Jahn-Teller effect; at very low temperatures, it produces a kind of “magnetic stripe sandwich,” with alternating stripes of ferrimagnetic and antiferromagnetic atomic chains.

    “This is fundamental work,” Li says, to determine “any intrinsic capacity limits to sodium manganese dioxide” — such as how much charge it can hold, or how many times it can go through the charge-discharge cycle without degradation. The ultimate goal is to find out “how [to] make a higher-capacity sodium-ion battery electrode,” Li says.

    In addition to possible battery applications, the work led to the finding that sodium manganese dioxide forms bands of magnetic domains at temperatures of 60 kelvins (-352 degrees Fahrenheit) or less. This finding, Li says, may be important to the emerging field of spin electronics, where the spin states of electrons, rather than their electrical charges, carry and store information.

    Even before this new research, Li says, batteries made of this sodium-ion composition “showed comparable capacity to the commercial lithium-ion batteries,” which are one of the leading technologies in production today. While no companies are now producing sodium-ion batteries, the technology has great potential: Sodium is more abundant, less expensive, and safer to work with than lithium.

    “This is still fairly basic research,” Li says, adding: “Understanding always pushes us forward, especially in this field. You only make progress by understanding these materials better.”

    The work also included researchers Dong Su at Brookhaven National Laboratory, Juan-Carlos Idrobo at Oak Ridge National Laboratory, and Jeffrey W. Lynn at the National Institute of Standards and Technology, as well as seven others from MIT. It was partly funded by the Samsung Advanced Institute of Technology and the U.S. Department of Energy.

    See the full article here.

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 3:05 pm on August 20, 2013 Permalink | Reply
    Tags: , Battery technology, ,   

    From PNNL Lab: “Controlling Oxygen May Stop Batteries from Slowly Fading” 

    Atoms’ departure leaves electrons that irreversibly change the cathode

    Results: When oxygen atoms escape, they change the local electronic structure and cause the voltage to fade in a next-generation battery, according to theoreticians at Pacific Northwest National Laboratory and University College London, UK. A lithium, manganese, nickel cathode has a high energy density and charges and releases energy quickly, but it fades too soon for commercial use. The team found the release of oxygen leaves vacancies throughout the structure along with stray electrons. The vacancies promote structural disor­der that reduces the energy barrier for lithium ions to leave the cathode and reduces the battery’s voltage, just as seen in earlier experiments.

    ‘Our simulated voltage curves respond like those seen in real experimental situation,’ said Dr. Maria Sushko, the materials scientist at PNNL who led the study. ‘We are modeling the material using a realistic structure with defects and disorder rather than some idealized material.’

    cath
    Next generation lithium-ion batteries fade, releasing less energy each time the battery is charged. Because the battery fades, it has to be replaced, at an environmental and financial cost. A recent study by theoreticians at Pacific Northwest National Laboratory and University College London answers decades-old questions about the underlying microscopic processes.

    Why It Matters: Lithium-ion batteries fade, releasing less energy each time the battery is charged. Over time, the battery’s voltage declines to the point that it is no longer viable and has to be replaced, at both an environmental and financial cost. This study answers decades-old questions about the underlying microscopic processes. The team shows how the loss of oxygen atoms and the formation of nickel- and magnesium-rich areas cause fading. This new information assists in the knowledge-based design of longer lasting materials for cell phones, laptop computers, and electric cars.

    ‘Overall, this research matters in moving forward on battery technologies,’ said Dr. Kevin Rosso, a Laboratory Fellow at PNNL who co-led this 6-month study. ‘Batteries that do not fade would let electronic devices work longer without recharging and make them more stable.'”

    See the full article here.

    Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy National Laboratories, managed by the Department of Energy’s Office of Science. The main campus of the laboratory is in Richland, Washington.

    PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.

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  • richardmitnick 1:37 pm on August 19, 2013 Permalink | Reply
    Tags: , Battery technology, ,   

    From SLAC: “Designer Glue Improves Lithium-ion Battery Life” 

    August 19, 2013
    Mike Ross

    “When it comes to improving the performance of lithium-ion batteries, no part should be overlooked – not even the glue that binds materials together in the cathode, researchers at SLAC and Stanford have found.

    Tweaking that material, which binds lithium sulfide and carbon particles together, created a cathode that lasted five times longer than earlier designs, according to a report published last month in Chemical Science. The research results are some of the earliest supported by the Department of Energy’s Joint Center for Energy Storage Research.

    ‘We were very impressed with how important this binder was in improving the lifetime of our experimental battery,’ said Yi Cui, an associate professor at SLAC and Stanford who led the research.

    glue
    A new binder material forms a fine-grained (top) lithium sulfide/carbon composite cathode, compared with the large clumps (bottom) that form when another common binder is used. In an operating lithium-ion battery, the larger clumps caused the battery to be ruined after just 100 charge/discharge cycles. In contrast, an experimental battery using the new binder lasted nearly five times longer. (Zhi Wei Seh/Stanford)

    Researchers worldwide have been racing to improve lithium-ion batteries, which are one of the most promising technologies for powering increasingly popular devices such as mobile electronics and electric vehicles. In theory, using silicon and sulfur as the active elements in the batteries’ terminals, called the anode and cathode, could allow lithium-ion batteries to store up to five times more energy than today’s best versions. But finding specific forms and formulations of silicon and sulfur that will last for several thousand charge-discharge cycles during real-life use has been difficult.

    Cui’s group was exploring how to create a better cathode by using lithium sulfide rather than sulfur. The lithium atoms it contains can provide the ions that shuttle between anode and cathode during the battery’s charge/discharge cycle; this in turn means the battery’s other electrode can be made from a non-lithium material, such as silicon. Unfortunately, lithium sulfide is also electrically insulating, which greatly reduces any battery’s performance. To overcome this, electrically conducting carbon particles can be mixed with the sulfide; a glue-like material – the binder – holds it all together.

    Scientists in Cui’s group devised a new binder that is particularly well-suited for use with a lithium sulfide cathode – and that also binds strongly with intermediate polysulfide molecules that dissolve out of the cathode and diminish the battery’s storage capacity and useful lifetime.

    The experimental battery using the new binder, known by the initials PVP, retained 94 percent of its original energy-storage capacity after 100 charge/discharge cycles, compared with 72 percent for cells using a conventionally-used binder, known as PVDF. After 500 cycles, the PVP battery still had 69 percent of its initial capacity.

    Cui said the improvement was due to PVP’s much stronger affinity for lithium sulfide; together they formed a fine-grained lithium sulfide/carbon composite that made it easier for lithium ions to penetrate and reach all of the active material within the cathode. In contrast, the previous binder, PVDF, caused the composite to grow into large clumps, which hindered the lithium ions’ penetration and ruined the battery within 100 cycles

    Even the best batteries lose some energy-storage capacity with each charge/discharge cycle. Researchers aim to reduce such losses as much as possible. Further enhancements to the PVP/lithium sulfide cathode combination will be needed to extend its lifetime to more than 1,000 cycles, but Cui said he finds it encouraging that improving the usually overlooked binder material produced such dramatic benefits.”

    See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SLAC Campus


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  • richardmitnick 8:24 pm on February 7, 2013 Permalink | Reply
    Tags: , Battery technology, , ,   

    From SLAC: “For Superionic Material, Smaller is Better” 


    SLAC National Accelerator Laboratory

    Mike Ross
    February 7, 2013

    “A material that could enable faster memory chips and more efficient batteries can switch between high and low ionic conductivity states much faster than previously thought, SLAC and Stanford researchers have determined. The key is to use extremely small chunks of it.

    ‘Our result is a step toward using this material, copper sulfide, in low-cost solid-state electrical batteries,’ said the leader of the research team, Aaron Lindenberg, of the Stanford Institute for Materials and Energy Sciences and the Stanford PULSE Institute. The institutes are run jointly by SLAC and Stanford.

    simes

    pulse

    ‘For the first time, we’ve seen the atomic-scale details of exactly how these nanoscale materials transform, or switch, from a state that is poorly conducting to one that is highly conducting,’ he said. ‘And what we’ve learned gives us confidence about our ability to tune its structure and properties to be useful in new technologies.’

    Lindenberg’s team reported its results last month in Nature Communications.”

    See the full article here.

    SLAC Campus
    SLAC National Accelerator Laboratory is home to a two-mile linear accelerator—the longest in the world. Originally a particle physics research center, SLAC is now a multipurpose laboratory for astrophysics, photon science, accelerator and particle physics research.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.


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  • richardmitnick 2:36 pm on January 25, 2013 Permalink | Reply
    Tags: , Battery technology,   

    From ORNL Lab: “ORNL research paves way for larger, safer lithium ion batteries” 

    i1

    Friday, January 25, 2013
    Morgan McCorkle

    Looking toward improved batteries for charging electric cars and storing energy from renewable but intermittent solar and wind, scientists at Oak Ridge National Laboratory have developed the first high-performance, nanostructured solid electrolyte for more energy-dense lithium ion batteries.

    matrix
    ORNL researchers developed a nanoporous solid electrolyte (bottom left and in detail on right) from a solvated precursor (top left). The material conducts ions 1,000 times faster than its natural bulk form and enables more energy-dense lithium ion batteries.

    Today’s lithium-ion batteries rely on a liquid electrolyte, the material that conducts ions between the negatively charged anode and positive cathode. But liquid electrolytes often entail safety issues because of their flammability, [read this, Boeing] especially as researchers try to pack more energy in a smaller battery volume. Building batteries with a solid electrolyte, as ORNL researchers have demonstrated, could overcome these safety concerns and size constraints.

    ‘To make a safer, lightweight battery, we need the design at the beginning to have safety in mind, said ORNL’s Chengdu Liang, who led the newly published study in the Journal of the American Chemical Society.”

    See the full article here.

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