Agency Research Program Research Articles

Fluorination of Vanadium Oxy-Phosphate By Lif: Electrochemical Behavior in Li-Ion Battery

Polyanionic materials display a wide range of possible available compositions leading to a great amount of different properties. Therefore, they are attracting interest in the field of Li-ion battery research. Tavorite type compositions offer a rich crystal chemistry, among which LiVPO4F delivers the highest theoretical energy density ([1]–[3]). These materials benefit from the inductive effect of both phosphate and F- anions, which lowers the energy of a given Mn/Mn-1 redox couple (with M being the transition metal). This property induces the formation of a more ionic metal-ligand bond, a lower antibonding orbital level energy and therefore a higher potential difference vs. Li. Therefore, lithium transition metal fluoro-phosphates are an appealing class of materials for Li-ion batteries since they are capable to operate at very high potential compared to other phosphates (Li3V2(PO4)3, LiVPO4O, LiFePO4 etc.). One of the possible methods to synthesize such compounds is by incorporation of LiF in the phosphate materials, such as the method used to produce LiVPO4F, in which LiF is reacted with VPO4 to obtain the fluorinated phase LiVPO4F [1],[3]. In this work, a new class of fluoro-phosphates (Li1+ x VPO4OF x ) is synthesized by incorporation of LiF into vanadium oxy-phosphates. It is worthwhile to note that Li1+ x VPO4OF x is different than LiVPO4F1- x O x for which fluorine is substituted by oxygen through a simple oxidation of LiVPO4F upon air [4]. The new fluorinated materials were obtained through a two-step ceramic synthesis. In the first step, vanadium oxy-phosphates with the general formula Li x VPO4O (with x = 0, 1 and 2) were synthesized. In the second step, the oxy-phosphate materials are mixed with LiF and annealed at high temperatures. The powders obtained through the incorporation of LiF in LiVPO4O (Li1+ x VPO4OF x ) crystallized in Tavorite type structure with a unit cell slightly bigger than LiVPO4O (V/Z of 86 A3 vs. 85.5 A3), as was calculated from XRD patterns (Figure 1a). The obtained material was further studied by NMR and x-ray absorption spectroscopy. The electrochemical behavior (Figure 1b) of Li1+ x VPO4OF x exhibited an operating potential higher than LiVPO4O (4.15 V vs. 3.95 V) when the same redox potential is involved (V3+/V4+). The mechanism of Li+ extraction and/or insertion is being tackled by in situ XRD during electrochemical cycling. Acknowledgements: This work has received funding from the European Union‘s Horizon 2020 research and innovation program under Grant Agreement No 711792 (LiRichFCC) and from the Slovenian Research Agency research program P2-0393. [1] J. Barker, M. Y. Saidi, and J. and Swoyer, “Lithium Metal Fluorophosphate and Preparation Thereof, US Patent,” 2005. [2] J. Barker, M. Y. Saidi, and J. L. Swoyer, “Electrochemical Insertion Properties of the Novel Lithium Vanadium Fluorophosphate, LiVPO[sub 4]F,” J. Electrochem. Soc., vol. 150, no. 10, p. A1394, 2003. [3] J.-M. Ateba Mba, C. Masquelier, E. Suard, and L. Croguennec, “Synthesis and Crystallographic Study of Homeotypic LiVPO4F and LiVPO4O,” Chem. Mater., vol. 24, no. 6, pp. 1223–1234, 2012. [4] E. Boivin, R. David, J. N. Chotard, T. Bamine, A. Iadecola, L. Bourgeois, E. Suard, F. Fauth, D. Carlier, C. Masquelier, and L. Croguennec, “LiVPO4F1- yOyTavorite-Type Compositions: Influence of the Concentration of Vanadyl-Type Defects on the Structure and Electrochemical Performance,” Chem. Mater., vol. 30, no. 16, pp. 5682–5693, 2018. Figure1. (a) XRD patterns and (b) Electrochemical cycling (3-4.5 V) of LiVPO4O, Li1+ x VPO4OF x and LiVPO4F for comparison. Figure 1

In vivo performance of a matrix-based quantitative ultrasound imaging device dedicated to calcaneus investigation

We developed a prototype of an ultrasound (US) bone matrix densitometer, the BEAM scanner, in the context of a European Space Agency research program. This device, which is a contact imaging device, was designed to overcome the limitations of immersion devices in space. Broadband US attenuation (BUA) and speed of sound (SOS) parameters were calculated from the radiofrequency (RF) signal. The principle aim of this study was to evaluate in vivo performance in direct comparison with a currently available device (UBIS 3000, DMS, France). The short-term precision of the BEAM scanner for BUA was estimated at 2.8%, whereas it was 2.3% with UBIS 3000. The short-term precision for SOS was 0.3%, and this was the same as the coefficient of variation (CV) of the UBIS 3000. CVs of 3.4% and 0.6% for midterm precision were found for BUA and SOS, respectively, and UBIS 3000 scores were 3% and 0.4%, respectively. This preliminary study demonstrates the high performance of the BEAM scanner and its new concept offers a wide range of improvements and new applications. (E-mail: defontai@med.univ-tours.fr)

Pork Takes a Bite Out of NASA's Science Budget

ACADEMIC EARMARKSAcross the country, dozens of universities, museums, and research organizations scored windfalls in NASA's 2000 budget in the form of unrequested spending, called earmarks, inserted by Congress. Although academic pork projects are nothing new in the federal budget, the dollar amounts at NASA are increasing dramatically, and space science's share has risen even more steeply. The specially designated projects are also beginning to pose a significant threat to established agency research programs and peer-reviewed science, say NASA officials.

The influence of the user on the results of multizone air flow simulations with COMIS

The multizone airflow simulation program COMIS was evaluated within an International Energy Agency research program. One of the steps in the evaluation procedure is to test the user–code interface, consisting not only in the appearance of the computer screen, but also in the user guide or any other tutorial or help system. The user–code interface of COMIS was then tested through round robin tests. Two types of problems were submitted to several users: a simple and well-defined problem and a real world problem. This study first allowed great improvements of the user guide. While results for the well-defined case were very close to each other, large differences were observed for the `real world' case. Results of simulation largely depend on the user options, and users easily make modelling errors when the studied case becomes complex.

Accelerated Extraction of Organic Pollutants Using Microwave Energy

This study, which is part of an ongoing U.S. Environmental Protection Agency research program, carried out by the National Exposure Research Laboratory, Characterization Research Division-Las Vegas (formerly Environmental Monitoring Systems Laboratory-Las Vegas), addresses new sample preparation techniques that prevent or minimize pollution in the laboratory ; improve target analyte recoveries ; and reduce sample preparation costs. In this paper, the extraction of 16 phenolic compounds and 20 organochlorine pesticides (OCPs) from spiked soil, sand, and organic compost samples is addressed. Six phenols are also extracted from a certified reference soil. The conditions for extraction are a hexane-acetone (1 :1) solvent in closed vessels at 115°C for 10 min using microwave energy.

Supersonic jets' effect on ozone still hazy

Intriguing results are springing from initial attempts to assess how a fleet of supersonic jets flying in the stratosphere might affect Earth's protective ozone layer. For example, atmospheric modelers find in the first approximation that nitrogen oxide emissions from supersonic aircraft would destroy ozone. But if certain reactions on aerosols are included in the models, the impact is just the opposite—that is, ozone increases rather than decreases. Clearly there are some fundamental questions we don't understand, says Michael J. Prather, atmospheric scientist with the National Aeronautics & Space Administration's Goddard Institute for Space Studies in New York City and manager of the agency's research program on the atmospheric effects of stratospheric aircraft. How important are heterogeneous reactions? What are the key measurements we need? NASA is spending $284 million over six years to try to answer those questions and many others about second-generation supersonic planes dubbed high-speed civil...

Urban Storm-Induced Discharge Impacts: US Environmental Protection Agency Research Program Review

Fecal coliform bacteria (and pathogens), high flow rates, sediment, toxic heavy metals and organic pollutants are most commonly associated with urban receiving water problems. Most beneficial uses have been shown to be adversely affected by urban runoff, including shell fish harvesting, fish and aquatic life propagation, drinking water supplies, aesthetics and recreation. Most of the problems occur over long periods of time and are not associated with individual runoff events, making cause and effect relationships difficult to study. The Storm and Combined Sewer Program of the U.S. Environmental Protection Agency has sponsored several long-term research projects to investigate these problems, along with data reviews to identify urban runoff problems from available information. Current research efforts are stressing sources and controls for toxicants in urban runoff.

The environmental protection agency's research program on total human exposure

The U.S. Environmental Protection Agency's (U.S. EPA) research program on total human exposure to environmental pollution seeks to develop a newly emerging concept in the environmental sciences. Instead of focusing purely on the sources of pollution or their transport and movement through the environment, this research focuses on human beings as the receptors of these pollutants. People and daily activities become the center of attention. The methodology measures and models the pollutant concentrations found at the physical boundaries of people, regardless of whether the pollutants arrive through the air, water, food, or skin. It seeks to characterize quantitatively the impact of pollution on people by determining if an environmental problem exists at the human interface and, if so, by determining the sources, nature, extent, and severity of this environmental problem. By exploiting an emerging new arsenal of miniaturized instruments and by developing statistically representative survey designs for sampling the population of cities, significant progress has been made in recent years in providing previously unavailable human exposure field data needed for making valid risk assessments. The U.S. EPA total human exposure research program includes: development of measurement methods and instruments, development of exposure models and statistical protocols, microenvironmental field studies, total human exposure studies, validation of human exposure models with empirical data, and dosage research investigations.

ERL Director resigns in protest

George H. Ludwig resigned in protest last month from his post as director of the National Oceanic and Atmospheric Administration (NOAA) Environmental Research Laboratories (ERL). Ludwig, who will retire in February 1984 after 30 years of government service, told Eos that he resigned “with the intent of making a statement” about changes within NOAA that he says are weakening the agency's research program. Ludwig is now the assistant to the National Aeronautics and Space Administration's (NASA) chief scientist.“The NOAA reorganization process of the past year has been unusually traumatic for ERL,” Ludwig explained in a memo to his ERL colleagues when he announced his departure. “Specific actions have shifted many of ERL's long‐standing management responsibilities elsewhere in the [Department of Commerce] and NOAA.”

A review of the U.S. Environmental Protection Agency's Research Program on the prevention and control of hazardous material spills

This paper is a status report on a number of the projects in progress at the Industrial Waste Treatment Research Laboratory of the U.S. Environmental Protection Agency at Edison, New Jersey. The actual causes of numerous hazardous material spills have been documented and analyzed to assign priority to operational areas in which spill prevention and control procedures are urgently needed. Spill alert systems are ready for installation on marginally safe earthen holding pond dikes. Fail-safe systems are being evaluated to reduce spillage from overfilling and from transfer line rupture. The handling of spills in municipalities has been addressed with particular attention to the maintenance and utilization of secondary sewage treatment facilities during spill events. Among the physical and chemical treatment systems that have been or are being produced are trailer-mounted units for processing contaminated water. Also, special devices are being designed for the dispersion and recovery — where necessary — of adsorbents and counteractive chemical reagents for in situ treatment of polluted water bodies. Plastic foams have been developed to dike or confine spills and to plug leaks in ruptured containers. A pickup truck-mounted collection unit, consisting of a battery-powered pump and a self-deploying plastic storage bag, has been constructed and tested. Nearing final testing is a “Sea Curtain”, which extends from the bottom of a stream to the air above. The “Curtain” can be used to isolate a water column that is being contaminated by a soluble, sinking, or floating hazardous material discharged from shore or in stream. Gelling and solidification agents have been shown to be effective in immobilizing spilled hazardous materials. Systems are being built to reprocess treatment agents for reuse and to detoxify whatever agents or recovered materials cannot be salvaged. Field-use packets and other easy-to-deploy items are being developed to trace spills in water and to assess the effectiveness of cleanup. Procedures for enhanced, in-place, biological degradation of spilled hazardous materials are under test. The thrust of the Laboratory's program in these and in related projects is toward the demonstration of practical procedures, hardware, and suitably engineered systems for the prevention and control of spills of hazardous materials.