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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Room-Temperature Pseudo-Solid-State Iron Fluoride Conversion Battery with High Ionic Conductivity

Li-metal batteries (LMBs) employing conversion cathode materials (e.g., FeF 3 ) are a promising way to prepare inexpensive, environmentally friendly batteries with high energy density. Pseudo-solid-state ionogel separators harness the energy density and safety advantages of solid-state LMBs, while alleviating key drawbacks (e.g., poor ionic conductivity and high interfacial resistance). In this work, a pseudo-solid-state conversion battery (Li-FeF 3 ) is presented that achieves stable, high rate (1.0 mA cm –2 ) cycling at room temperature. The batteries described herein contain gel-infiltrated FeF 3 cathodes prepared by exchanging the ionic liquid in a polymer ionogel with a localized high-concentration electrolyte (LHCE). The LHCE gel merges the benefits of a flexible separator (e.g., adaptation to conversion-related volume changes) with the excellent chemical stability and high ionic conductivity (~2 mS cm –1 at 25 °C) of an LHCE. The latter property is in contrast to previous solid-state iron fluoride batteries, where poor ionic conductivities necessitated elevated temperatures to realize practical power levels. Importantly, the stable, room-temperature Li-FeF 3 cycling performance obtained with the LHCE gel at high current densities paves the way for exploring a range of architectures including flexible, three-dimensional, and custom shape batteries.

25 ENERGY STORAGE↗
NASA NTRS1992

Studies of the kinetics and mechanisms of perfluoroether reactions on iron and oxidized iron surfaces

Polymeric perfluoroalkylethers are being considered for use as lubricants in high temperature applications, but have been observed to catalytically decompose in the presence of metals. X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) were used to explore the decomposition of three model fluorinated ethers on clean polycrystalline iron surfaces and iron surfaces chemically modified with oxygen. Low temperature adsorption of the model fluorinated ethers on the clean, oxygen modified and oxidized iron surfaces was molecular. Thermally activated defluorination of the three model compounds was observed on the clean iron surface at remarkably low temperatures, 155 K and below, with formation of iron fluoride. Preferential C-F bond scission occurred at the terminal fluoromethoxy, CF3O, of perfluoro-1-methoxy-2-ethoxy ethane and perfluoro-1-methoxy-2-ethoxy propane and at CF3/CF2O of perfluoro-1,3-diethoxy propane. The reactivity of the clean iron toward perfluoroalkylether decomposition when compared to other metals is due to the strength of the iron fluoride bond and the strong electron donating ability of the metallic iron. Chemisorption of an oxygen overlayer lowered the reactivity of the iron surface to the adsorption and decomposition of the three model fluorinated ethers by blocking active sites on the metal surface. Incomplete coverage of the iron surface with chemisorbed oxygen results in a reaction which resembles the defluorination reaction observed on the clean iron surface. Perfluoro-1-methoxy-2-ethoxy ethane reacts on the oxidized iron surface at 138 K, through a Lewis acid assisted cleavage of the carbon oxygen bond, with preferential attack at the terminal fluoromethoxy, CF3O. The oxidized iron surface did not passivate, but became more reactive with time. Perfluoro-1-methoxy-2-ethoxy propane and perfluoro-1,3-diethoxy propane desorbed prior to the observation of decomposition on the oxidized iron surface.

Napier, Mary E.↗
DOE OSTI2026

Revealing the Roles of CuF 2 /NiF 2 Incorporation in the Electrochemical Performance of FeF 3 Cathodes in Solid‐State Batteries

Mixed metal fluorides have been considered as a promising candidate to lower the voltage hysteresis of conversion-type iron fluoride cathodes, but their cycling stability is limited due to transition metal dissolution and interphase growth in liquid electrolyte batteries. Here, we study the role of incorporating CuF 2 and NiF 2 in the electrochemical performance of FeF 3 cathode in halide-based solid-state batteries to test whether we can transfer the kinetic benefit of low voltage hysteresis to solid-state batteries while using solid electrolyte to eliminate transition metal dissolution and stabilize the interphase. Synchrotron X-ray absorption spectroscopy results indicated the redox reactions are attributed to Cu 0 /Cu + and Fe 0 /Fe 2+ in 25CuF 2 -75FeF 3 and Ni 0 /Ni 2+ and Fe 0 /Fe 3+ in 10NiF 2 -90FeF 3 . While no apparent improvement in electrode kinetics can be observed, the incorporation of CuF 2 and NiF 2 can largely improve the cycling stability of FeF 3 cathodes. In conclusion, the results demonstrate the advantages of using solid-state concept to improve the cycling stability of conversion-type cathodes.

25 ENERGY STORAGE↗
NASA NTRS2013

Performance and Analysis of Perfluoropolyalkyl Ether Grease Used on Space Shuttle Actuators--A Case Study

Actuators used on the United States space shuttle fleet are lubricated with unspecified amounts of Braycote 601 (Castrol Braycote) grease consisting of a perfluoropolyalkyl ether (PFPAE) base oil thickened with a polytetrafluoroethylene (PTFE) filler. Each shuttle has four body flap actuators (BFAs) (two on each wing) on a common segmented shaft and four rudder speed brake (RSB) actuators. The actuators were designed to operate for 10 years and 100 flights without periodic relubrication. Visible inspection of two partially disassembled RSB actuators in continuous use for 19 years raised concerns over possible grease degradation due to discoloration of the grease on several places on the surfaces of the gears. Inspection revealed fretting, micropitting, wear and corrosion of the bearings and gears. A small amount of oil dripped from the disassembled actuators. Whereas new grease is beige in appearance, the discolored grease consisted of both grey and reddish colors. Grease samples taken from the actuators together with representative off-the-shelf new and unused grease samples were analyzed by gravimetry for oil content; by inductively coupled plasma spectroscopy (ICP) for metals content; Fourier transform infrared (FTIR) spectroscopy for base oil decomposition; and by size exclusion chromatography (SEC) for determination of the molecular weight distributions of the grease oil. The Braycote 601 grease was stable after 19 years of continuous use in the sealed RSB actuators and was fit for its intended purpose. There were no significant chemical differences between the used grease samples and new and unused samples. Base oil separation was not significant within the sealed actuators. No corrosive effect in the form of iron fluoride was detected. The grey color of grease samples was due to metallic iron. The red color was due to oxidation of the metallic wear particles from the gears and the bearings comprising the actuators.

Morales, Wilfredo↗
NASA NTRS1996

Fabrication of Iron-Containing Carbon Materials From Graphite Fluoride

Carbon materials containing iron alloy, iron metal, iron oxide or iron halide were fabricated. Typical samples of these metals were estimated to contain 1 iron atom per 3.5 to 5 carbon atoms. Those carbon materials containing iron alloy, iron metal, and/or Fe3O4 were magnetic. The kinetics of the fabrication process were studied by exposing graphite fluoride (CF(0.68)) to FeCl3 over a 280 to 420 C temperature range. Between 280 and 295 C, FeCl3 quickly entered the structure of CF(0.68), broke the carbon-fluorine bonds, and within 10 to 30 min, completely converted it to carbon made up of graphite planes between which particles of crystalline FeF3 and noncrystalline FeCl3 were located. Longer reaction times (e.g., 28 hr) or higher reaction temperatures (e.g., 420 C) produced materials containing graphite, a FeCl3-graphite intercalation compound, FeCl2(center dot)4H2O, and FeCl2(center dot)2H2O. These products were further heat treated to produce iron-containing carbon materials. When the heating temperature was kept in the 750 to 850 C range, and the oxygen supply was kept at the optimum level, the iron halides in the carbon structure were converted to iron oxides. Raising the heat to temperatures higher than 900 C reduced such iron oxides to iron metal. The kinetics of these reactions were used to suggest processes for fabricating carbon materials containing iron alloy. Such processes were then tested experimentally. In one of the successful trial runs, commercially purchased CF(0.7) powder was used as the reactant, and NiO was added during the final heating to 1200 C as a source of both nickel and oxygen. The product thus obtained was magnetic and was confirmed to be a nickel-iron alloy in carbon.

Hung, Ching-cheh↗
NASA NTRS1983

Sound velocity anisotropy in cubic crystals

Simple analytical expressions may be derived for sound velocities in cubic crystals by using lattice harmonics or functions which are invariant under the crystal symmetry operations. These expressions are in good agreement with the exact results for typical crystals such as metallic iron and potassium fluoride.

Tsang, T.↗
NASA NTRS1983

Sound velocity anisotropy in cubic crystals

Simple analytical expressions may be derived for sound velocities in cubic crystals by using lattice harmonics or functions which are invariant under the crystal symmetry operations. These expressions are in good agreement with the exact results for typical crystals such as metallic iron and potassium fluoride.

Tsang, T.↗
NASA NTRS1992

Lunar mining of oxygen using fluorine

An important aspect of lunar mining will be the extraction of volatiles, particularly oxygen, from lunar rocks. Thermodynamic data show that oxygen could readily be recovered by fluorination of abundant lunar anorthite, CaAl2Si2O8. Fluorine is the most reactive element, and the only reagent able to extract 100 percent of the oxygen from any mineral, yet it can safely be stored or reacted in nickel or iron containers. The general fluorination reaction, mineral + 2F2 = mixed fluorides = O2, has been used for more than 30 years at a laboratory scale by stable-isotope geochemists. For anorthite, metallic Al and Si may be recovered from the mixed fluorides by Na-reduction, and CaO via exchange with Na2O; the resulting NaF may be recycled into F2 and Na by electrolysis, using lanthanide-doped CaF2 as the inert anode.

Burt, Donald M.↗
NASA NTRS2006

Experimental Demonstration of the Molten Oxide Electrolysis Method for Oxygen and Iron Production from Simulated Lunar Materials

This paper presents the results of a Marshall Space Flight Center funded effort to conduct an experimental demonstration of the processing of simulated lunar resources by the molten oxide electrolysis (MOE) process to produce oxygen and metal from lunar resources to support human exploration of space. Oxygen extracted from lunar materials can be used for life support and propellant, and silicon and metallic elements produced can be used for in situ fabrication of thin-film solar cells for power production. The Moon is rich in mineral resources, but it is almost devoid of chemical reducing agents, therefore, molten oxide electrolysis, MOE, is chosen for extraction, since the electron is the most practical reducing agent. MOE was also chosen for following reasons. First, electrolytic processing offers uncommon versatility in its insensitivity to feedstock composition. Secondly, oxide melts boast the twin key attributes of highest solubilizing capacity for regolith and lowest volatility of any candidate electrolytes. The former is critical in ensuring high productivity since cell current is limited by reactant solubility, while the latter simplifies cell design by obviating the need for a gas-tight reactor to contain evaporation losses as would be the case with a gas or liquid phase fluoride reagent operating at such high temperatures. In the experiments reported here, melts containing iron oxide were electrolyzed in a low temperature supporting oxide electrolyte (developed by D. Sadoway, MIT).

Curreri, P. A.↗
NASA NTRS2006

Lunar Metal Oxide Electrolysis with Oxygen and Photovoltaic Array Production Applications

This paper presents the results of a Marshall Space Flight Center funded effort to conduct an experimental demonstration of the processing of simulated lunar resources by the molten oxide electrolysis (MOE) process to produce oxygen and metal from lunar resources to support human exploration of space. Oxygen extracted from lunar materials can be used for life support and propellant, and silicon and metallic elements produced can be used for in situ fabrication of thin-film solar cells for power production. The Moon is rich in mineral resources, but it is almost devoid of chemical reducing agents, therefore, molten oxide electrolysis, MOE, is chosen for extraction, since the electron is the most practical reducing agent. MOE was also chosen for following reasons. First, electrolytic processing offers uncommon versatility in its insensitivity to feedstock composition. Secondly, oxide melts boast the twin key attributes of highest solubilizing capacity for regolith and lowest volatility of any candidate electrolytes. The former is critical in ensuring high productivity since cell current is limited by reactant solubility, while the latter simplifies cell design by obviating the need for a gas-tight reactor to contain evaporation losses as would be the case with a gas or liquid phase fluoride reagent operating at such high temperatures. In the experiments reported here, melts containing iron oxide were electrolyzed in a low temperature supporting oxide electrolyte (developed by D. Sadoway, MIT). The production of oxygen and reduced iron were observed. Electrolysis was also performed on the supporting electrolyte with JSC-1 Lunar Simulant. The cell current for the supporting electrolyte alone is negligible while the current for the electrolyte with JSC-1 shows significant current and a peak at about -0.6 V indicating reductive reaction in the simulant.

Curreri, P. A.↗
NASA NTRS2000

Microscopic physical biomarkers in carbonate hot springs: implications in the search for life on Mars

Physical evidence of life (physical biomarkers) from the deposits of carbonate hot springs were documented at the scale of microorganisms--submillimeter to submicrometer. The four moderate-temperature (57 to 72 degrees C), neutral pH springs reported on in this study, support diverse communities of bacteria adapted to specific physical and chemical conditions. Some of the microbes coexist with travertine deposits in endolithic communities. In other cases, the microbes are rapidly coated and destroyed by precipitates but leave distinctive mineral fabrics. Some microbes adapted to carbonate hot springs produce an extracellular polymeric substance which forms a three-dimensional matrix with living cells and cell remains, known as a biofilm. Silicon and iron oxides often coat the biofilm, leading to long-term preservation. Submicrometer mineralized spheres composed of calcium fluoride or silica are common in carbonate hot spring deposits. Sphere formation is biologically mediated, but the spheres themselves are apparently not fossils or microbes. Additionally, some microbes selectively weather mineral surfaces in distinctive patterns. Hot spring deposits have been cited as prime locations for exobiological exploration of Mars. The presence of preserved microscopic physical biomarkers at all four sites supports a strategy of searching for evidence of life in hot spring deposits on Mars.

NASA Center JSC↗
DOE OSTI2024

Data and scripts associated with a manuscript investigating dissolved organic matter and microbial community linkages across seven globally distributed rivers

This data package is associated with the publication “Meta-metabolome ecology reveals that geochemistry and microbial functional potential are linked to organic matter development across seven rivers” submitted to Science of the Total Environment. This data package includes the data necessary to replicate the analyses presented within the manuscript to investigate dissolved organic matter (DOM) development across broad spatial distances and within divergent biomes. Specifically, we included the Fourier transform ion cyclotron mass spectrometry (FTICR-MS) data, geochemistry data, annotated metagenomic data, and results from ecological null modeling analyses in this data package. Additionally, we included the scripts necessary to generate the figures from the manuscript. Complete metagenomic data associated with this data package can be found at the National Center for Biotechnology (NCBI) under Bioproject PRJNA946291. This dataset consists of (1) four folders; (2) a file-level metadata (flmd) file; (3) a data dictionary (dd) file; (4) a factor sheet describing samples; and (5) a readme. The FTICR Data folder contains (1) the processed Fourier transform ion cyclotron mass spectrometry (FTICR-MS) data; (2) a transformation-weighted characteristics dendrogram generated from the FTICR-MS data; and (3) the script used to generate all FTICR-MS related figures. The Geochemical Data folder contains (1) the single geochemistry data file and (2) the R script responsible for generating associated figures. The Metagenomic Data folder contains (1) annotation information across different levels; (2) carbohydrate active enzyme (CAZyme) information from the dbCAN database (Yin et al., 2012); (3) phylogenetic tree data (FASTAs, alignments, and tree file); and (4) the scripts necessary to analyze all of these data and generate figures. The Null Modeling Data folder contains (1) data generated during null modeling for each river and all rivers combined and (2) the R scripts necessary to process the data. All files are .csv, .pdf, .tsv, .tre, .faa, .afa, .tree, or .R.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1985

Polarized polymer films as electronic pulse detectors of cosmic dust particles

A new type of dust particle detector has been developed which consists of a polarized film of polyvinylidene fluoride (PVDF) having conducting electrons on its surface and operating with no bias voltage. Here, the response characteristics of PVDF detectors with areas in the range 4-150 sq cm and thickness in the range 2-28 microns to iron particles accelerated to velocities in the range 1-12 km/s are reported. The discussion also covers the mechanism of detection, fast pulse response, noise characteristics, and the dependence of the detector signal amplitude on particle mass and velocity. The detectors exhibit long-term stability and can be operated for extended periods of time over the temperature range -50 to +50 C; their response to dust particle impacts is unaffected by high background fluxes of charged particles.

Simpson, J. A.↗