Compact batteries enhanced by spontaneous silver matrix formations

Optical images of the non-discharged cathode, showing key differences in the lithium-facing and steel-facing sides. Credit: Image courtesy of Brookhaven National Laboratory

In a promising lithium-based battery, the formation of a highly conductive silver matrix transforms a material otherwise plagued by low conductivity. To optimize these multi-metallic batteries -- and enhance the flow of electricity -- scientists needed a way to see where, when, and how these silver, nanoscale "bridges" emerge.

Now, researchers from the U.S. Department of Energy's Brookhaven National Laboratory and Stony Brook University have used x-rays to map this changing atomic architecture and revealed its link to the battery's rate of discharge. The study -- published online Jan. 8, 2015, in the journal Science -- shows that a slow discharge rate early in the battery's life creates a more uniform and expansive conductive network, suggesting new design approaches and optimization techniques.

"Armed with this insight into battery cathode discharge processes, we can target new materials designed to address critical battery issues associated with power and efficiency," said study coauthor Esther Takeuchi, a SUNY Distinguished Professor at Stony Brook University and Chief Scientist in Brookhaven Lab's Basic Energy Sciences Directorate.

The scientists used bright x-ray beams at Brookhaven Lab's National Synchrotron Light Source (NSLS) -- a DOE Office of Science User Facility -- to probe lithium batteries with silver vanadium diphosphate (Ag2VP2O8) electrodes. This promising cathode material, which may be useful in implantable medical devices, exhibits the high stability, high voltage, and spontaneous matrix formation central to the research.

"The experimental work -- in particular the in-situ x-ray diffraction in batteries totally encased in stainless steel -- should prove useful for industry as it can penetrate prototype and production-level batteries to track their structural evolution during operation," Takeuchi said.

Into the matrix

As these single-use batteries -- synthesized and assembled by Stony Brook graduate student David Bock -- discharge, the lithium ions stored in the anode travel to the cathode, displacing silver ions along the way. The displaced silver then combines with free electrons and unused cathode material to form the conductive silver metal matrix, acting as a conduit for the otherwise impeded electron flow.

"To visualize the cathode processes within the battery and watch the silver network take shape, we needed a very precise system with huseigh-intensity x-rays capable of penetrating a steel battery casing," said study coauthor and Stony Brook University Research Associate Professor Amy Marschilok. "So we turned to NSLS."

Energy dispersive x-ray diffraction (EDXRD) at NSLS provided this real-time -- in situ -- visualization data. In EDXRD, intense beams of x-rays passed through the sample, losing energy as the battery structure bent the beams. Each set of detected beam angles, like time-lapse images, revealed the shifting chemistry as a function of battery discharge.

"The silver forms in particles spanning less than 10 nanometers, and the diffraction patterns can be both dense and faint," said Brookhaven Lab scientist Zhong Zhong, who performed the critical alignment for the x-ray experiments at NSLS.

Once the data was collected, Brookhaven Lab postdoctoral researcher and study coauthor Kevin Kirshenbaum led the data analysis effort.

"This kind of analysis and interpretation requires considerable time and expertise, but the results can be stunning," Kirshenbaum said.

Surprises written in silver

In most batteries, the speed of lithium-ion diffusion determines the rate of discharge, a key factor in overall performance and efficiency. The material closest to the lithium anode would ordinarily discharge first, as the ions have a shorter distance to travel. In a surprising discovery, the researchers found that the material farthest from the anode and nearest the coin cell surface discharged first in the battery.

"This is because the non-discharged cathode material is a very poor electric conductor, so the resistance for lithium ion diffusion is less than for electron flow," said coauthor and SUNY Distinguished Teaching Professor Kenneth Takeuchi. "This highlights a uniquely efficient aspect of in situ silver matrix formation: The silver matrix forms primarily where needed, which is more efficient than using conductive additives."

The in situ diffraction data was combined with two techniques applied after operation: x-ray absorption spectroscopy (XAS) and angle-resolved x-ray diffraction (XRD).

Spectroscopy can reveal exact chemistry because each element absorbs and emits light uniquely, but the x-rays used for XAS cannot penetrate the battery casing. So after each step in the discharge, the researchers removed the cathode and ground it into a powder to measure the average elemental composition. Chia-Ying Lee of the University at Buffalo prepared the reduced cathode materials for the initial ex situ measurements.

"These techniques provide complementary data: the in situ diffraction shows where the silver is formed within the cathode, while the spectroscopy shows more precisely how much silver was formed," Esther Takeuchi said.

Brighter lights and better batteries

NSLS ended its 32-year experimental run in September 2014, but its powerful successor is 

already taking data at Brookhaven Lab. The National Synchrotron Light Source II (NSLS-II) provides beams 10,000 times brighter than NSLS, and in situ energy research is a major part of its mission. NSLS-II, also a DOE Office of Science User Facility, will soon welcome users from industry, academia, and other national labs.

"We are currently working on other materials that form conductive networks and hope to study them as functioning cells," Takeuchi said. "The brighter beams and greater spatial resolution of NSLS-II will be a great tool in studying other cathodes and pushing this technology forward."

This research was funded by the U.S. Department of Energy's Office of Science.

Source: Brookhaven National Laboratory

'Iron Sun' is not a rock band, but a key to how stars transmit energy

Physicist Jim Bailey of Sandia National Laboratories observes a wire array that will heat foam to roughly 4 million degrees until it emits a burst of X-rays that heats a foil target to the interior conditions of the sun. Credit: Photo by Randy Montoya, Sandia National Laboratories

Working at temperatures matching the interior of the sun, researchers at Sandia National Laboratories' Z machine have been able to determine experimentally, for the first time in history, iron's role in inhibiting energy transmission from the center of the sun to near the edge of its radiative band -- the section of the solar interior between the sun's core and outer convection zone.

Because that role is much greater than formerly surmised, the new, experimentally derived amount of iron's opacity -- essentially, its capacity for hindering the transport of radiative energy originating in nuclear fusion reactions deep in the sun's interior -- helps close a theoretical gap in the Standard Solar Model, widely used by astrophysicists as a foundation to model the behavior of stars.

"Our data, when inserted into the theoretical model, bring its predictions more closely into alignment with physical observations," said Sandia lead investigator Jim Bailey. His team's work appeared Jan. 1 in the journal Nature.

The gap between the model and observations appeared in 2000 when analysis of spectra emerging from the sun forced scientists to lower their estimates of energy-absorbing elements such as oxygen, nitrogen and carbon by 30 to 50 percent.

The decreased abundances meant that the model then predicted that energy would arrive at the sun's radiative edge more readily than before. This created a discrepancy between the star's theoretical structure and its measured structure, which is based on variations in temperatures and densities at different locations.

To make the model once again agree with observations, scientists needed a way to balance the decreased resistance to radiation transport caused by the lowered amounts of the elements.

Bailey's experimental group, including Taisuke Nagayama, Guillaume Loisel and Greg Rochau, in painstaking experiments spanning a 10-year period, discovered that the widely used astrophysical estimate of the wavelength-dependent opacity of iron should be increased between 30 to 400 percent. That difference does not represent a large uncertainty but rather how much iron's opacity varies with the wavelength of the radiation.

"This represents roughly half the change in the mean opacity needed to resolve the solar problem, even though iron is only one of many elements that contribute," the authors write in their paper.

Getting accurate data has been difficult, as "the inside of a star is one of the most mysterious places in the universe," Bailey said. "It's too opaque for distant instruments to see inside and analyze reactions within it, and too hot to send a probe into it. It has also been too difficult to run tests under appropriate conditions in a laboratory. So the physics that describes how atoms, embedded in solar plasma, absorb radiation, has never been experimentally tested. Yet that process dominates the way energy generated by nuclear reactions in the sun's interior is transported to the outside.

"Fortunately, in our Z experiments, we can create temperature and density conditions nearly the same as the region inside the sun that affects the discrepancy the most -- the edge of the zone where radiative energy transport dominates -- in a sample that's big enough, lasts long enough, and is uniform enough to test. We used that new capability to measure the opacity of iron, one of a few elements that plays the most important part in radiative energy transfer."

Iron is important because, of all the elements abundant in the sun, it maintains the highest number of bound electrons essential in radiative energy transfer, and thus has a large effect on the outcome of solar models.

Still, the upward revision of opacities as a solution is bound to be controversial.

"No matter what we do, we can't make measurements at all the different conditions we need to know," said Nagayama. "There are 20 elements present, and a large range of temperatures and densities. We study iron because its complex electronic structure is a challenge to represent in opacity theories. And it is important in solar physics. The sun is a test bed to model other stars. Without experimental tests, we don't know if these models are accurate. To the extent we fail to understand the sun, then the workings of other stars are subject to some uncertainty."

Sandia's Z machine creates the temperature of the sun's interior -- about 2.1 million degrees -- in a target about the size of a grain of sand. From that small sample, Bailey could do what theorists cannot: hold in his hand tangible evidence for the way iron atoms behave inside stars.

The target design for recent experiments involved intermingled iron and magnesium, tamped by plastic and beryllium layers on both sides. Radiation streaming through the sample heats up the iron and magnesium, which expand. The plastic restrains the expansion to keep it more uniform for opacity measurements. Magnesium provides information about corresponding density and temperature.

The work was sponsored by the National Nuclear Security Administration and the DOE Office of Science.

Source: DOE/Sandia National Laboratories

CASIS research set for launch aboard SpaceX mission to space station

The Bone Densitometer developed by Techshot, Inc. will enable X-ray testing for research studies aboard the International Space Station. Credit: CASIS

This fall marks another commercial cargo flight to the International Space Station. In September, SpaceX's Dragon spacecraft is scheduled to blast off to the orbital laboratory carrying supplies and investigations as part of the company's fourth contracted mission to the complex.

Included in the cargo will be the third suite of research investigations sponsored by the Center for the Advancement of Science in Space (CASIS). With the role of managing the U.S. National Laboratory on the space station, CASIS is responsible for brokering and facilitating research investigations on the station with clear Earth applications and benefits.

The latest collection of CASIS-sponsored research, termed Advancing Research Knowledge (ARK)-2, centers heavily on life sciences. Studies include those focused on drug development, disease understanding and validation testing. Each investigation will use the unique conditions aboard the space station to advance researchers' understanding in those areas of study.

Additionally, CASIS and NASA have partnered with Techshot Inc., of Greenville, Indiana, to develop a new hardware device capable of assisting with research that may improve understandings of muscle wasting and diseases like osteoporosis.

The CASIS-sponsored hardware and life science investigations destined for the space station's national laboratory include the Bone Densitometer, which will be the first X-ray machine installed on the space station. A joint project between CASIS, NASA and Techshot, the facility will be instrumental in conducting rodent research on station. The Bone 

Densitometer will allow astronauts to examine bone density of model organisms in space through the use of Dual-Energy X-ray Absorptiometry (DEXA) technology. In short, researchers will be able to assess bone density loss by measuring energy levels absorbed by bones via the device.

The Rodent Research-1 investigation kicks off a series of NASA and CASIS-sponsored investigations focused on rodent research aboard the space station. The study will be the first to use the Bone Densitometer in an effort to help scientists examine the effects of long duration spaceflight. There are numerous applications to these investigations including studying bone loss, muscle atrophy and cardiovascular anomalies. However, the primary focus of this inaugural mission will be to assess the operational capabilities of the new hardware designed for these investigations.

The Drug Metabolism study will assist researchers in the area of drug development and human biology. This investigation is led by a scientist from the U.S. Department of Veteran Affairs, Dr. Timothy Hammond, who is looking to study yeast cells in microgravity. The goal of this investigation is to explore the changes in these cells in space to improve drug development for various diseases, including cancer therapeutics.

The Protein Crystal Optimization study is an investigation aiming to leverage the unique location of the space station to examine the internal structure of three medically important proteins. The space environment should allow researchers to grow the selected protein crystals to an optimal size and quality to allow for closer examination via neutron diffraction. This protein crystal growth in microgravity may reveal new characteristics that are masked by gravity on Earth. By studying these three proteins, medically relevant to salmonella infection, peptic ulcer disease, and biomarkers for heart attack and liver disease, researchers can apply insights towards improved treatments.

A New Era In Commercial Use of the Space Station

The space station's national laboratory affords researchers the ability to conduct experiments in a distinctive environment with factors and variables that are near impossible to replicate on the ground. With access to our nation's only orbiting laboratory, CASIS works with new and non-traditional users to take advantage of this resource. A great example of novel commercial research heading to station is the Cobra Puma Golf investigation.

The Cobra Puma Golf-electroplating investigation, also launching aboard SpaceX, is a materials science investigation sponsored by CASIS in collaboration with COBRA PUMA Golf (CPG). The CPG research and development team will examine the impacts of microgravity on electroplating -- the process of coating a metallic surface using an electric current. The study will test a variety of coating substances on materials used in golf equipment manufacturing. The insight gained from this investigation will aid CPG in identifying improved material development techniques.

CPG's project is another example of a commercial user leveraging the capabilities of the ISS National Lab to advance ground research. Through brokering research investigations with commercial companies, CASIS hopes to demonstrate the space station is not only a test-bed for groundbreaking research and development, but a unique laboratory that can help differentiate investigations initiatives from ground-based studies.

The mission is another milestone for the space community, showcasing how commercial endeavors can work hand-in-hand with research goals. The studies of ARK-2 exemplify the diverse possibilities for the space station and users of the research platform. From commercial launch providers that transport investigations to space, to commercial researchers looking to use the national laboratory, science in space is good for life on Earth.

Source: NASA

Turning the Moon into a cosmic ray detector

Artists rendition of the SKA. Credit: SKA Organisation

Scientists from the University of Southampton are to turn the Moon into a giant particle detector to help understand the origin of Ultra-High-Energy (UHE) cosmic rays -- the most energetic particles in the Universe.

The origin of UHE cosmic rays is one of the great mysteries in astrophysics. Nobody knows where these extremely rare cosmic rays come from or how they get their enormous energies. Physicists detect them on Earth at a rate of less than one particle per square kilometre per century.

Dr Justin Bray, a Research Fellow in Cosmic Magnetism at the University of Southampton, is lead author of a proposal to use the Square Kilometre Array (SKA), set to become the largest and most sensitive radio telescope in the world, to detect vastly more UHE cosmic rays by using the Moon as a giant cosmic ray detector.

On Earth, physicists detect these high-energy particles when they hit the upper atmosphere triggering a cascade of secondary particles that generate a short and faint burst of radio waves only a few nanoseconds long.

It is this signal that astronomers hope to pick up from the Moon, but as these signals are so short and faint no radio telescope on Earth is currently capable of picking them up.
With its large collecting area and high sensitivity, the SKA will be able to detect these signals using the visible lunar surface -- millions of square kilometres -- giving the researchers access to more data about UHE cosmic rays than they have ever had before.

The current largest detector on Earth is the Pierre Auger Observatory in Argentina that covers an area of 3,000 square kilometres, about the size Luxembourg. The SKA will be more than 10 times larger (33,0000 square kilometres) and researchers hope to detect around 165 UHE cosmic rays a year from the Moon compared to the 15-a-year currently observed.

Dr Bray announced details of the project at a major SKA conference in Italy.. He says: "Cosmic rays at these energies are so rare that you need an enormous detector to collect a significant number of them -- but the moon dwarfs any particle detector that has been built so far. If we can make this work, it should give us our best chance yet to figure out where they're coming from."

Dr Bray is working with Professor Anna Scaife, also from Physics and Astronomy at the University of Southampton, who leads the development of the SKA's Imaging Pipeline as part of the Science Data Processor (SDP) work package consortium.

Professor Scaife says: "Defining science goals for the telescope is crucial for ensuring that the appropriate technical capabilities are considered during the design phase."

Using a network of radio antennas in the Southern hemisphere, the SKA will advance our understanding of how the Universe evolved and challenge Einstein's theory of relativity. With receivers across Australia and Africa, its dishes and antennas will provide detailed information on the large scale 3D structure of the Universe.

When operational in the early 2020's, the SKA radio telescope will produce more than 10 times the current global traffic of the Internet in its internal telecommunications system. To play back a single day's worth of SKA data on an MP3 player would take about two million years.

Source: University of Southampton

NASA's Chandra X-ray Observatory celebrates 15th anniversary

To celebrate Chandra's 15th anniversary, four newly processed images of supernova remnants have been released. Credit: NASA/CXC/SAO

Fifteen years ago, NASA's Chandra X-ray Observatory was launched into space aboard the Space Shuttle Columbia. Since its deployment on July 23, 1999, Chandra has helped revolutionize our understanding of the universe through its unrivaled X-ray vision.

Chandra, one of NASA's current "Great Observatories," along with the Hubble Space Telescope and Spitzer Space Telescope, is specially designed to detect X-ray emission from hot and energetic regions of the universe.

With its superb sensitivity and resolution, Chandra has observed objects ranging from the closest planets and comets to the most distant known quasars. It has imaged the remains of exploded stars, or supernova remnants, observed the region around the supermassive black hole at the center of the Milky Way, and discovered black holes across the universe. Chandra also has made a major advance in the study of dark matter by tracing the separation of dark matter from normal matter in collisions between galaxy clusters. It is also contributing to research on the nature of dark energy.

To celebrate Chandra's 15th anniversary, four new images of supernova remnants -- the Crab Nebula, Tycho, G292.0+1.8, and 3C58 -- are being released. These supernova remnants are very hot and energetic and glow brightly in X-ray light, which allows Chandra to capture them in exquisite detail.

"Chandra changed the way we do astronomy. It showed that precision observation of the X-rays from cosmic sources is critical to understanding what is going on," said Paul Hertz, NASA's Astrophysics Division director in Washington. "We're fortunate we've had 15 years -- so far -- to use Chandra to advance our understanding of stars, galaxies, black holes, dark energy, and the origin of the elements necessary for life."

Chandra orbits far above Earth's X-ray absorbing atmosphere at an altitude up to 139,000 km (86,500 mi), allowing for long observations unobscured by Earth's shadow. When it was carried into space in 1999, it was the largest satellite ever launched by the shuttle.

"We are thrilled at how well Chandra continues to perform," said Belinda Wilkes, director of the Chandra X-ray Center (CXC) in Cambridge, Massachusetts. "The science and operations teams work very hard to ensure that Chandra delivers its astounding results, just as it has for the past decade and a half. We are looking forward to more ground-breaking science over the next decade and beyond."

Originally called the Advanced X-ray Astrophysics Facility (AXAF), the telescope was first proposed to NASA in 1976. Prior to its launch aboard the shuttle, the observatory was renamed in honor of the late Indian-American Nobel laureate, Subrahmanyan Chandrasekhar. Known to the world as Chandra (which means "moon" or "luminous" in Sanskrit), he was widely regarded as one of the foremost astrophysicists of the 20th century.

"Chandra continues to be one of the most successful missions that NASA has ever flown as measured against any metric -- cost, schedule, technical success and, most of all, scientific discoveries," said Martin Weisskopf, Chandra Project Scientist at the Marshall Space Flight Center in Huntsville, Ala. "It has been a privilege to work on developing and maintaining this scientific powerhouse, and we look forward to many years to come."

To help celebrate this anniversary, Chandra scientists -- including former CXC Director, Harvey Tananbaum -- will participate in a Google+ Hangout July 22 beginning at 3 p.m. EDT. For more information on this event, visit: http://go.nasa.gov/1jXcXYT

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

Source: NASA

Scientists have reproduced the conditions inside the magma chamber of a supervolcano to understand what it takes to trigger its explosion.

This artist’s impression depicts the magma chamber of a supervolcano with partially molten magma at the top. The pressure from the buoyancy is sufficient to initiate cracks in the Earth’s crust in which the magma can penetrate. Credit: ESRF/Nigel Hawtin

Scientists have reproduced the conditions inside the magma chamber of a supervolcano to understand what it takes to trigger its explosion. These rare events represent the biggest natural catastrophes on Earth except for the impact of giant meteorites. Using synchrotron X-rays, the scientists established that supervolcano eruptions may occur spontaneously, driven only by magma pressure without the need for an external trigger. The results are published in Nature Geosciences.

The team was led by Wim Malfait and Carmen Sanchez-Valle of ETH Zurich (Switzerland) and comprised scientists from the Paul Scherrer Institute in Villigen (Switzerland), Okayama University (Japan), the Laboratory of Geology of CNRS, Université Lyon 1 and ENS Lyon (France) and the European Synchrotron (ESRF) in Grenoble (France).

A well-known supervolcano eruption occurred 600,000 years ago in Wyoming in the United States, creating a huge crater called a caldera, in the centre of what today is Yellowstone National Park. When the volcano exploded, it ejected more than 1000 km3 of ash and lava into the atmosphere, 100 times more than Mt Pinatubo in the Philippines did in 1992. Big volcanic eruptions have a major impact on the global climate. The Mt Pinatubo eruption decreased the global temperature by 0.4 degrees Celsius for a few months. The predictions for a super volcano are a fall in temperatures by 10 degrees Celsius for 10 years.

According to a 2005 report by the Geological Society of London, "Even science fiction cannot produce a credible mechanism for averting a super-eruption. We can, however, work to better understand the mechanisms involved in super-eruptions, with the goal of being able to predict them ahead of time and provide a warning for society. Preparedness is the key to mitigation of the disastrous effects of a super-eruption."

The mechanisms that trigger supervolcano eruptions have remained elusive to date. The main reason is that the processes inside a supervolcano are different from those in conventional volcanoes like Mt. Pinatubo which are better understood. A supervolcano possesses a much larger magma chamber and it is always located in an area where the heat flow from the interior of Earth to the surface is very high. As a consequence, the magma chamber is very large and hot but also plastic: its shape changes as a function of the pressure when it gradually fills with hot magma. This plasticity allows the pressure to dissipate more efficiently than in a normal volcano whose magma chamber is more rigid. Supervolcanoes therefore do not erupt very often.

So what changes in the lead up to an eruption? Wim Malfait explains: "The driving force is an additional pressure which is caused by the different densities of solid rock and liquid magma. It is comparable to a football filled with air under water, which is forced upwards by the denser water around it." Whether this additional pressure alone could eventually become sufficiently high to crack Earth's crust, leading to a violent eruption, or whether an external energy source like an Earthquake is required has only now been answered.

Whilst it is virtually impossible to drill a hole into the magma chamber of a supervolcano given the depth at which these chambers are buried, one can simulate these extreme conditions in the laboratory. "The synchrotron X-rays at the ESRF can then be used to probe the state -- liquid or solid -- and the change in density when magma crystallises into rock" says Mohamed Mezouar, scientist at the ESRF and member of the team. Jean-Philippe Perrillat from the Laboratory of Geology of CNRS, Université Lyon 1 and ENS Lyon adds: "Temperatures of up to 1700 degrees and pressures of up to 36,000 atmospheres can be reached inside the so-called Paris-Edinburgh press, where speck-sized rock samples are placed between the tips of two tungsten carbide anvils and then heated with a resistive furnace. This special set-up was used to accurately determine the density of the liquid magma over a wide range of pressures and temperatures."

Magma often includes water, which as vapour adds additional pressure. The scientists also determined magma densities as a function of water content.

The results of their measurements showed that the pressure resulting from the differences in density between solid and liquid magma rock is sufficient in itself to crack more than ten kilometres of Earth's crust above the magma chamber. Carmen Sanchez-Valle concludes: "Our research has shown that the pressure is actually large enough for Earth's crust to break. The magma penetrating into the cracks will eventually reach Earth's surface, even in the absence of water or carbon dioxide bubbles in the magma. As it rises to the surface, the magma will expand violently, which is the well known origin of a volcanic explosion."


Source: CNRS

Summary: Scientists have reproduced the conditions inside the magma chamber of a supervolcano to understand what it takes to trigger its explosion. These rare events represent the biggest natural catastrophes on Earth except for the impact of giant meteorites. Using synchrotron X-rays, the scientists established that supervolcano eruptions may occur spontaneously, driven only by magma pressure without the need for an external trigger.