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  • richardmitnick 10:20 am on January 20, 2016 Permalink | Reply
    Tags: , Battery technology, Neutron scattering,   

    From ORNL: “ORNL researchers use neutrons to gain insight into battery inefficiency” 

    i1

    Oak Ridge National Laboratory

    January 19, 2016
    Dawn Levy, Communications
    levyd@ornl.gov
    865.576.6448

    Temp 1
    In a Fluid Interface Reactions, Structures and Transport Center project to probe a battery’s atomic activity during its first charging cycle, Robert Sacci and colleagues used the Spallation Neutron Source’s vibrational spectrometer to gain chemical information. Image credit: Oak Ridge National Laboratory, U.S. Dept. of Energy; photographer Genevieve Martin.

    Rechargeable batteries power everything from electric vehicles to wearable gadgets, but obstacles limit the creation of sleeker, longer-lasting and more efficient power sources. Batteries produce electricity when charged atoms, known as ions, move in a circuit from a positive end (anode) to a negative end (cathode) through a facilitating mix of molecules called an electrolyte.

    Scientists at the Department of Energy’s Oak Ridge National Laboratory are improving the lifetimes of rechargeable batteries that run on lithium, a small atom that can pack tightly into graphite anode materials. The valuable ions are depleted as a battery charges, and they are also lost to the formation of a thin coating on a battery’s anode during initial charging. ORNL researchers used two of the most powerful neutron science facilities in the world to try to understand the dynamics behind this phenomenon.

    In a paper published in the Journal of Physical Chemistry C, the ORNL researchers focused on the spontaneous growth of the thin coating, called the solid-electrolyte interphase (SEI). This nanoscale coating protects and stabilizes the new battery, but it comes at a cost. The electrolyte, a mixture of molecules composed of hydrogen, carbon, lithium and oxygen, is forced to break down to form this film.

    “The big picture is to increase the amount of lithium we can put into a battery,” said Robert Sacci, lead author and Materials Science and Technology Division scientist. “When you develop a battery, you put in excess lithium because a lot of that lithium gets eaten up or taken away from usability to form this thin film.”

    Sacci and colleagues used beams of subatomic particles called neutrons to delve into a battery’s atomic reactivity during its first charging cycle. Neutrons were necessary because they can easily enter three-dimensional structures and are sensitive to changes in hydrogen concentration, a major component of electrolytes.

    ORNL researchers targeted anode samples with neutrons from the Spallation Neutron Source (SNS), the world’s most intense pulsed beam, and the High Flux Isotope Reactor (HFIR), the highest continuous-beam research reactor in the United States. They tracked the scattered paths of the neutrons after the beams penetrated the material, creating a constantly updating map of the sample’s molecular dynamics.

    ORNL Spallation Neutron Source
    ORNL Spallation Neutron Source

    ORNL High Flux Isotope Reactor
    ORNL High Flux Isotope Reactor

    Neutron scattering is key to understanding battery activity on the atomic scale. While the diffracted beams of neutrons would appear to be a jumbled mess to most—like lights dancing off a disco ball in all directions—skilled scientists use these scattering signals to calculate chemical and structural changes while the SEI layer develops.

    Is battery film friend or foe?

    Once the SEI layer forms, it buffers degradation of the electrolyte and prevents a dangerous buildup of metal deposits on the lithiated-graphite anode, increasing a battery’s life cycle.

    Sacci and his team wondered if a pre-made film could protect the anode while minimizing the consumption of lithium ions.

    The ORNL scientists incorporated lithium atoms into vacancies within graphite through grinding at high force. The result was a powdery, charged anode material that they then dipped into an electrolyte solution.

    A thin film formed around each lithiated-graphite particle, encapsulating it. At this point, the scientists were ready to subject samples to neutron scattering tests to gain a fresh perspective into how an SEI layer generates during initial charging of a lithium-ion battery.

    Researchers used SNS’s vibrational spectrometer, VISION, to gain chemical information about the SEI layer. HFIR allowed the ORNL scientists to use small-angle neutron scattering (SANS) techniques to map the thin film’s structure and chart new information about its formation.

    “With VISION, we can measure the vibrations of atoms, which tell us how they are bound within molecules, and with SANS, a scattering instrument at HFIR, you’re looking more or less at how big the particles are and how they are arranged,” Sacci said.

    After exploring the lithiated-graphite anode material, Sacci and his fellow energy researchers now understand the chemical process by which the thin protective layer generates on the anode.

    “We were able to definitely say, yes a polymer formed, the particles appeared bigger—which means a layer grew on them—and they were more interconnected,” said Sacci.

    “The advantage of forming this polymeric solid-electrolyte interface prior to battery assembly is that the battery would last longer, and that it’s a good stepping stone to giving us clues into how to design these artificial interfaces.”

    This research was supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy Office of Science. Work was performed at the Spallation Neutron Source and the High Flux Isotope Reactor, DOE Office of Science User Facilities at ORNL.

    UT-Battelle manages ORNL for DOE’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov/.—by Ashanti B. Washington

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    ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.

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  • richardmitnick 9:47 am on December 14, 2015 Permalink | Reply
    Tags: , Battery technology,   

    From COSMOS: “Batteries – a guide to the future” 

    Cosmos Magazine bloc

    COSMOS

    14 Dec 2015
    Viviane Richter

    Batteries that store renewable energy are essential for the Paris climate agreement to work. Viviane Richter describes the rechargeable batteries that could make it happen.

    Temp 1

    Turning solar and wind electricity into a 24/7 power source as reliable as coal. Eliminating the “range anxiety” that stops people switching from petrol to electric cars. Stopping the irritation of flat smartphones or laptops.

    Those are just a few of the advantages that affordable long-lived rechargeable batteries, capable of delivering a sustained high-powered output over weeks instead of days could offer.

    According to the experts, we have the technology. What we don’t have is the magic mix of affordability, lightness and power delivery in a single battery. Instead, rechargeable batteries are diversifying, spawning a range of storage tools, each best suited to a particular niche. Here we meet the five frontrunners.

    Reigning champion — the lithium ion battery

    1
    Tesla Powerwall Credit: Tesla

    Potential use: Almost everything – devices, electric cars, household renewable energy storage.
    Advantages: Proven, mature technology.
    Disadvantages: Most gains in energy storage have already been made. Some safety concerns.

    Lithium ion battery are the reigning champions when it comes to energy density — the amount of electric charge stored by weight.

    And the technology is well proven. Even sexy. Witness the sleek Tesla Powerwall, a large lithium ion battery pack that, connected to solar panels, could enable a household to disconnect from the grid. Meanwhile, Tesla CEO Elon Musk says the company’s Gigafactory in Nevada will produce enough lithium ion batteries to fit half million electric cars a year at a third of current costs.

    You can think of the lithium ion battery as a tiny water tower. When you charge your phone, electrons are pumped up into a storage tank called the “anode”, where they’re captured by lithium ions. Turning on your phone is like turning on the tap: electrons come flooding out of the lithium, and through your phone’s circuitry – before being collected in a receiver tank called the “cathode”.

    At the same time, the lithium ions cross the battery directly to reach the cathode. Here, electrons and lithium ion recombine – but as a spent force. Charging the battery re-energises the pair by pumping them back up to the anode.

    But there are safety concerns. Solvents in lithium ion batteries, such as diethyl carbonate, are inflammable and sometimes things go wrong. For example, in 2013 lithium batteries caused a fire on a Boeing’s 787 Dreamliner at Boston’s Logan International Airport, grounding the fleet.

    Such mishaps could be avoided if a new technology developed by Chunsheng Wang and colleagues at the University of Maryland in Baltimore pans out – a non-flammable salt solvent that can carry lithium ions, creating a battery with the same power as a conventional lithium ion battery. By fine-tuning the chemistry the team thinks it can push the battery’s performance further. He published his development in Science in November

    Still, the lithium ion battery won’t be the champion forever. When it comes to energy density, lithium ion batteries may be the best we’ve got, but the technology’s already been pushed “almost as far as it can go”, says Adam Best, a materials engineer at Commonwealth Scientific and Industrial Research Organisation in Melbourne.

    Second-in-command — the lithium sulfur battery

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    A new all-solid lithium-sulfur battery developed by an Oak Ridge National Laboratory team led by Chengdu Liang has the potential to reduce cost, increase performance and improve safety compared with existing designs.Credit: Oak Ridge National Laboratory, U.S. Dept. of Energy

    Potential use: Devices, electrical cars, household renewable energy storage.
    Advantages: Potentially 5x more energy dense than lithium ion
    Disadvantages: shorter lifespan than lithium ion batteries.

    Lithium sulfur is the next battery we’ll see rolled out commercially, says Cameron Shearer, materials engineer at Flinders University in Adelaide. Otis Energy, a UK-based company, has announced that next year they will sell this type of battery for electric cars and solar energy storage. But they could soon be powering smartphones too.

    Whereas conventional lithium ion batteries use a slab of graphite to capture lithium ions at the anode, this battery uses a lightweight slither of lithium itself. And at the cathode, the battery uses sulfur to soak up the spent lithium and electrons – again, a lighter option than the mixture of metals in a conventional lithium ion battery cathode.

    Their lighter construction and favourable electrochemistry means that, at least on paper, a lithium sulfur battery can hold five times more electrons than lithium ion batteries, weight for weight – and at lower cost (sulfur is cheap).

    But the lithium sulfur battery is not long-lived – the lithium and sulfur tend to react together and clog pores in the cathode, and the sulfur begins to decompose. One solution could be to wrap the battery in a thin protective polymer coat — this helps hold the sulfur together, according to work from chemists at the Toyota Research Institute of North America in Michigan published in Energy and Environmental Science in November.

    Shearer is a strong supporter of lithium sulfur batteries, predicting their reliability and lifespan will match lithium ion batteries within 10 years.

    Lives fast, dies young — the lithium air battery

    Potential use: Devices, electric cars.
    Advantages: Very light, and on paper 10x more energy dense than lithium ion.
    Disadvantages: Very short lifespan (so far).

    Rather than using sulfur to soak up lithium at its cathode, this battery uses oxygen from the air. When the battery is charged, the oxygen is exhaled again. As a result, these batteries are exceptionally light – on paper they could store 10 times more energy than a lithium ion battery of the same weight. That’s your smartphone powered for more than a week on one charge – or an electric car with range longer than a petrol car with a full tank.

    “If you can make lithium-air work, you’ve pretty much got the most energy dense device available to man,” says Best.

    Sadly, so far the lithium air battery’s lifespan is even worse than lithium sulfur’s. And for the same old reasons – clogged cathodes, in this case because the lithium reacts with other molecules in the air.

    “It’s losing around 10 to 20 % [capacity] each time it’s cycled,” says Best. In October in Science, researchers at the University of Cambridge revealed a better type of lithium air battery. It contains a different anode that happily tolerates lithium hydroxide particles that form when lithium reacts with moisture in the air. But reaction with nitrogen still clogs the cathode.

    We’re unlikely to see lithium air move from lab bench to the market any time soon. “It’s 10 to 20 years away, if that,” says Best.

    Slow, chubby and cheap — the sodium ion battery

    Potential use: devices, electric car, household renewable energy storage
    Advantages: Lower cost than lithium ion.
    Disadvantages: Lower performance than lithium ion.

    Lithium has so far quenched our thirst for portable electronics, but demand for lithium is rising – an electric car battery requires about four kilograms. And lithium isn’t cheap, which will continue to push up the price of batteries as lithium becomes scarcer.

    Enter the sodium ion battery. It works like a lithium ion battery but uses cheaper, more abundant sodium as its electron source. The drawback is that it is not as energy dense – sodium atoms are bigger and heavier than lithium.

    For now, that takes it out the running for mobile applications such as electronic devices and electric cars, but not for solar energy storage, where cost is critical and size and weight less of an issue. Faradion, a UK-based company, and Aquion Energy, a US company, are already selling sodium ion batteries for these purposes.

    And if lithium prices do spike? That could provide the incentive for mass manufacture of sodium ion batteries – they could be ready for use in phones and laptops, in perhaps as little as five years, according to some estimates.
    The alien — the flow battery

    Potential use: Storage of renewable energy.
    Advantages: Cheap and reliable.
    Disadvantages: Low energy density. Must be stationary because of the heavy liquids and pumps.

    The flow battery promises to be the heavy-duty storage workhorse.

    Flow batteries don’t use an anode or cathode – they store energy by shuttling electrons between two large tanks of liquid. In place of lithium, most flow batteries use vanadium. Where lithium ions need to latch on to an anode or cathode to store electrons, vanadium ions are stable in solution.

    Flow batteries have a long lifetime as there is no solid anode or cathode to degrade. What’s more, it’s easy to increase capacity – simply feed in more solution.

    Their drawback is low energy density. The ions need a lot of liquid to be stable and this liquid needs to be pumped around to keep the ions evenly distributed. That makes the battery heavy and big – the smallest are about the size of a bar fridge. You wouldn’t use one in an electric car, let alone a phone.

    But at least one company, Australian firm Redflow, already sells flow batteries – for renewable energy storage at remote mine sites.

    Home use is also not out of the question. “The Tesla Powerwall is made to show off,” says Cameron Shearer of Flinders University in Adelaide. “You’d have a flow battery hidden in your wall.”

    How we’re designing new batteries has changed. “We’re moving from a sort of cottage industry to a much more sophisticated atomic design of materials,” says Anthony Vassallo, battery chemist at the University of Sydney. High-resolution microscopy techniques are enabling scientists to custom-design anodes, cathodes and other battery parts from the atoms up. Within five to 10 years, he estimates, nano-engineered battery components will be mass produced on 3D printers.

    Perhaps these could be the enabling technologies that springboard advanced batteries such as lithium air out of the lab and into real world renewable energy storage.

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  • richardmitnick 7:36 am on October 26, 2015 Permalink | Reply
    Tags: , Battery technology, ,   

    From EPFL: “An innovative response to the challenge of storing renewable energy” 

    EPFL bloc

    Ecole Polytechnique Federale Lausanne

    26.10.15
    Emmanuel Barraud

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    Inside the Container. Alain Herzog/EPFL

    A system for managing and storing energy, developed by EPFL’s Distributed Electrical Systems Laboratory, has been inaugurated on the school’s campus. The system, which received extensive co-financing from the Canton of Vaud, is built around an industrial-capacity battery developed by Vaud-based company Leclanché. It is now connected to the Romande Energie-EPFL solar park and will be used to conduct real-world tests on the behavior of a power grid that is fed electricity from solar panels.

    The experimental storage system was inaugurated today and is now connected to the Romande Energie-EPFL solar park, one of the largest in French-speaking Switzerland. Researchers will use it to study new, industrial-scale solutions for using renewable energies (especially solar energy) and feeding them into the power distribution grid, as part of the ‘EPFL Smart Grid’ project.

    Useful life far above average

    The system, which is the size of a shipping container, is unique for its underlying technology: it is based on high-performance lithium-ion titanate cells manufactured by Vaud-based company Leclanché. The life of these cells is around 15,000 charge-discharge cycles, while 3,000 is more common. In addition, the cells come with ceramic separators, patented by Leclanché, which are meant to maximize safety. It is a fully integrated solution comprising storage and energy-conversion modules as well as software for the battery to communicate with the EPFL engineers.

    Real-world testing

    The system will be used to test the research being carried out by Professor Mario Paolone, the Head of EPFL’s Distributed Electrical Systems Laboratory. It will be able to hold up to 500 kWh, which is the equivalent of the average energy consumed by fifty Swiss households over the course of one day, while managing variations in power as a function of the sunshine. “The ability to connect reliable energy storage solutions to the grid is key for incorporating renewable energy sources in our energy mix,” said Dr. Paolone. “Because of the system’s high capacity, we will be able for the first time to carry out real-world tests on the new control methods offered by the smart grids developed at EPFL.”

    A project co-financed by Canton of Vaud

    This project received extensive financial support from the Canton of Vaud. As part of its “100 million for renewable energies and energy efficiency” program, the Canton allocated some two million francs to Dr. Paolone’s team. These funds are from the R&D component of that program, which, in addition to EPFL, is providing support to the School of Business and Engineering in Yverdon-les-Bains and the University of Lausanne. “This project represents an important milestone in the implementation of our energy policy, one of the objectives of which is to develop renewable energy resources at the local level,” said Jacqueline de Quattro, State Councilor and Head of the Department of Territorial Planning and the Environment.

    The research involving the new system is set to last 23 months and will optimize the functioning of the various components of the new system, its management and its interoperability with an integrated electricity production and distribution network (i.e., a smart grid).

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    EPFL is Europe’s most cosmopolitan technical university. It receives students, professors and staff from over 120 nationalities. With both a Swiss and international calling, it is therefore guided by a constant wish to open up; its missions of teaching, research and partnership impact various circles: universities and engineering schools, developing and emerging countries, secondary schools and gymnasiums, industry and economy, political circles and the general public.

     
  • richardmitnick 10:09 am on August 18, 2015 Permalink | Reply
    Tags: , Battery technology, ,   

    From MIT: “Going solid-state could make batteries safer and longer-lasting” 


    MIT News

    August 17, 2015
    David L. Chandler

    1
    llustrations show the crystal structure of a superionic conductor. The backbone of the material is a body-centred cubic-like arrangement of sulphur anions. Lithium atoms are depicted in green, sulfur atoms in yellow, PS4 tetrahedra in purple, and GeS4 tetrahedra in blue. Researchers have revealed the fundamental relationship between anion packing and ionic transport in fast lithium-conducting materials. Image: Yan Wang

    New research paves the way for rechargeable batteries with almost indefinite lifetimes, researchers say.

    If you pry open one of today’s ubiquitous high-tech devices — whether a cellphone, a laptop, or an electric car — you’ll find that batteries take up most of the space inside. Indeed, the recent evolution of batteries has made it possible to pack ample power in small places.

    But people still always want their devices to last even longer, or go further on a charge, so researchers work night and day to boost the power a given size battery can hold. Rare, but widely publicized, incidents of overheating or combustion in lithium-ion batteries have also highlighted the importance of safety in battery technology.

    Now researchers at MIT and Samsung, and in California and Maryland, have developed a new approach to one of the three basic components of batteries, the electrolyte. The new findings are based on the idea that a solid electrolyte, rather than the liquid used in today’s most common rechargeables, could greatly improve both device lifetime and safety — while providing a significant boost in the amount of power stored in a given space.

    The results are reported in the journal Nature Materials in a paper by MIT postdoc Yan Wang, visiting professor of materials science and engineering Gerbrand Ceder, and five others. They describe a new approach to the development of solid-state electrolytes that could simultaneously address the greatest challenges associated with improving lithium-ion batteries, the technology now used in everything from cellphones to electric cars.

    The electrolyte in such batteries — typically a liquid organic solvent whose function is to transport charged particles from one of a battery’s two electrodes to the other during charging and discharging — has been responsible for the overheating and fires that, for example, resulted in a temporary grounding of all of Boeing’s 787 Dreamliner jets, Ceder explains. Others have attempted to find a solid replacement for the liquid electrolyte, but this group is the first to show that this can be done in a formulation that fully meets the needs of battery applications.

    Solid-state electrolytes could be “a real game-changer,” Ceder says, creating “almost a perfect battery, solving most of the remaining issues” in battery lifetime, safety, and cost.

    Costs have already been coming down steadily, he says. But as for safety, replacing the electrolyte would be the key, Ceder adds: “All of the fires you’ve seen, with Boeing, Tesla, and others, they are all electrolyte fires. The lithium itself is not flammable in the state it’s in in these batteries. [With a solid electrolyte] there’s no safety problem — you could throw it against the wall, drive a nail through it — there’s nothing there to burn.”

    The proposed solid electrolyte also holds other advantages, he says: “With a solid-state electrolyte, there’s virtually no degradation reactions left” — meaning such batteries could last through “hundreds of thousands of cycles.”

    The key to making this feasible, Ceder says, was finding solid materials that could conduct ions fast enough to be useful in a battery.

    “There was a view that solids cannot conduct fast enough,” he says. “That paradigm has been overthrown.”

    The research team was able to analyze the factors that make for efficient ion conduction in solids, and home in on compounds that showed the right characteristics. The initial findings focused on a class of materials known as superionic lithium-ion conductors, which are compounds of lithium, germanium, phosphorus, and sulfur, but the principles derived from this research could lead to even more effective materials, the team says.

    The research that led to a workable solid-state electrolyte was part of an ongoing partnership with the Korean electronics company Samsung, through the Samsung Advanced Institute of Technology in Cambridge, Massachusetts, Ceder says. That alliance also has led to important advances in the use of quantum-dot materials to create highly efficient solar cells and sodium batteries, he adds.

    This solid-state electrolyte has other, unexpected side benefits: While conventional lithium-ion batteries do not perform well in extreme cold, and need to be preheated at temperatures below roughly minus 20 degrees Fahrenheit, the solid-electrolyte versions can still function at those frigid temperatures, Ceder says.

    The solid-state electrolyte also allows for greater power density — the amount of power that can be stored in a given amount of space. Such batteries provide a 20 to 30 percent improvement in power density — with a corresponding increase in how long a battery of a given size could power a phone, a computer, or a car.

    The team also included MIT graduate student William Richards and postdoc Jae Chul Kim; Shyue Ping Ong at the University of California at San Diego; Yifei Mo at the University of Maryland; and Lincoln Miara at Samsung. The work is part of an alliance between MIT and the Samsung Advanced Institute of Technology focusing on the development of materials for clean energy.

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  • richardmitnick 7:35 am on March 22, 2015 Permalink | Reply
    Tags: , Battery technology,   

    From phys.org: “New processing technology converts packing peanuts to battery components” 

    physdotorg
    phys.org

    Mar 22, 2015
    Emil Venere

    1
    This schematic depicts a process for converting waste packing peanuts into high-performance carbon electrodes for rechargeable lithium-ion batteries that outperform conventional graphite electrodes, representing an environmentally friendly approach to reuse the waste. Credit: Purdue University image/Vinodkumar Etacheri

    Researchers have shown how to convert waste packing peanuts into high-performance carbon electrodes for rechargeable lithium-ion batteries that outperform conventional graphite electrodes, representing an environmentally friendly approach to reuse the waste.

    Batteries have two electrodes, called an anode and a cathode. The anodes in most of today’s lithium-ion batteries are made of graphite. Lithium ions are contained in a liquid called an electrolyte, and these ions are stored in the anode during recharging. Now, researchers at Purdue University have shown how to manufacture carbon-nanoparticle and microsheet anodes from polystyrene and starch-based packing peanuts, respectively.

    “We were getting a lot of packing peanuts while setting up our new lab,” recalled postdoctoral research associate Vinodkumar Etacheri. “Professor Vilas Pol suggested a pathway to do something useful with these peanuts.”

    This simple suggestion led to a potential new eco-friendly application for the packaging waste. Research findings indicate that the new anodes can charge faster and deliver higher “specific capacity” compared to commercially available graphite anodes, Pol said.

    The new findings are being presented during the 249th American Chemical Society National Meeting & Exposition in Denver on March 22-26. The work was performed by Etacheri, Pol and undergraduate chemical engineering student Chulgi Nathan Hong.

    “Although packing peanuts are used worldwide as a perfect solution for shipping, they are notoriously difficult to break down, and only about 10 percent are recycled,” Pol said. “Due to their low density, huge containers are required for transportation and shipment to a recycler, which is expensive and does not provide much profit on investment.”

    Consequently, packing peanuts often end up in landfills, where they remain intact for decades. Although the starch-based versions are more environmentally friendly than the polystyrene peanuts, they do contain chemicals and detergents that can contaminate soil and aquatic ecosystems, posing a threat to marine animals, he said.

    The new method “is a very simple, straightforward approach,” Pol said. “Typically, the peanuts are heated between 500 and 900 degrees Celsius in a furnace under inert atmosphere in the presence or absence of a transition metal salt catalyst.”

    The resulting material is then processed into the anodes.

    “The process is inexpensive, environmentally benign and potentially practical for large-scale manufacturing,” Etacheri said. “Microscopic and spectroscopic analyses proved the microstructures and morphologies responsible for superior electrochemical performances are preserved after many charge-discharge cycles.”

    Commercial anode particles are about 10 times thicker than the new anodes and have higher electrical resistance, which increase charging time.

    “In our case, if we are lithiating this material during the charging of a battery it has to travel only 1 micrometer distance, so you can charge and discharge a battery faster than your commercially available material,” Pol said.

    Because the sheets are thin and porous, they allow better contact with the liquid electrolyte in batteries.

    “These electrodes exhibited notably higher lithium-ion storage performance compared to the commercially available graphite anodes,” he said.

    Packing-peanut-derived carbon anodes demonstrated a maximum specific capacity of 420 mAh/g (milliamp hours per gram), which is higher than the theoretical capacity of graphite (372 mAh/g), Etacheri said.

    “Long-term electrochemical performances of these carbon electrodes are very stable,” he said. “We cycled it 300 times without significant capacity loss. These carbonaceous electrodes are also promising for rechargeable sodium-ion batteries. Future work will include steps to potentially improve performance by further activation to increase the surface area and pore size to improve the electrochemical performance.”

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    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

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