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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

SU-F-T-180: Evaluation of a Scintillating Screen Detector for Proton Beam QA and Acceptance Testing

Purpose: To test the performance of a commercial scintillating screen detector for acceptance testing and Quality Assurance of a proton pencil beam scanning system. Method: The detector (Lexitek DRD 400) has 40cm × 40cm field, uses a thin scintillator imaged onto a 16-bit scientific CCD with ∼0.5mm resolution. A grid target and LED illuminators are provided for spatial calibration and relative gain correction. The detector mounts to the nozzle with micron precision. Tools are provided for image processing and analysis of single or multiple Gaussian spots. Results: The bias and gain of the detector were studied to measure repeatability and accuracy. Gain measurements were taken with the LED illuminators to measure repeatability and variation of the lens-CCD pair as a function with f-stop. Overall system gain was measured with a passive scattering (broad) beam whose shape is calibrated with EDR film placed in front of the scintillator. To create a large uniform field, overlapping small fields were recorded with the detector translated laterally and stitched together to cover the full field. Due to the long exposures required to obtain multiple spills of the synchrotron and very high detector sensitivity, borated polyethylene shielding was added to reduce direct radiation events hitting the CCD. Measurements with a micro ion chamber were compared to the detector’s spot profile. Software was developed to process arrays of Gaussian spots and to correct for radiation events. Conclusion: The detector background has a fixed bias, a small component linear in time, and is easily corrected. The gain correction method was validated with 2% accuracy. The detector spot profile matches the micro ion chamber data over 4 orders of magnitude. The multiple spot analyses can be easily used with plan data for measuring pencil beam uniformity and for regular QA comparison.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-655: Evaluation of Neutron Dose Equivalent Inside of Treatment Vault of Radiotherapy by Photoneutron Production in the Primary Barriers

Purpose: Photon beams with energy higher than 10 MV interact with metal material in the primary barriers, where lead or steel have been widely used, neutrons can be generated. Monte Carlo simulations were performed to simulate the production of photoneutrons and the neutron shielding effect. Methods: For two photon beam energies, 15 MV and 18 MV, we simulated to strike metal sheets (steel and lead), and the ambient dose equivalents were calculated at the isocenter (in the patient plane) while delivering 1 Gy to the patient. For these cases, the thickness of the neutron shielding materials (Borated polyethylene (BPE) and concrete) were simulated to reduce the patient exposure by neutron doses. Results: When 18 MV photons interact with the metal sheets in the primary barrier, the evaluated neutron doses at the isocenter inside the treatment vault were 48.7 µSv and 7.3 µSv for lead and steel, respectively. In case of 15 MV photons, the calculated neutron doses were 18.6 µSv and 0.6 µSv for lead and steel, respectively. The neutron dose delivered to the patient can be reduced to negligible levels by including a 10 cm thick sheet of BPE or 22 cm thick sheet of concrete. Conclusion: When bunker shielding is designed with a primary barrier including a metal sheet inside the wall for a high energy machine, proper neutron shielding should be constructed to avoid undesirable extra dose.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2011

Wireless Solar Water Splitting Using Silicon-Based Semiconductors and Earth-Abundant Catalysts

We describe the development of solar water-splitting cells comprising earth-abundant elements that operate in near-neutral pH conditions, both with and without connecting wires. The cells consist of a triple junction, amorphous silicon photovoltaic interfaced to hydrogen- and oxygen-evolving catalysts made from an alloy of earth-abundant metals and a cobalt|borate catalyst, respectively. The devices described here carry out the solar-driven water-splitting reaction at efficiencies of 4.7% for a wired configuration and 2.5% for a wireless configuration when illuminated with 1 sun (100 milliwatts per square centimeter) of air mass 1.5 simulated sunlight. Fuel-forming catalysts interfaced with light-harvesting semiconductors afford a pathway to direct solar-to-fuels conversion that captures many of the basic functional elements of a leaf.

Reece, SY↗
DOE OSTI2020

Rationalizing Calcium Electrodeposition Behavior by Quantifying Ethereal Solvation Effects on Ca 2+ Coordination in Well-Dissociated Electrolytes

Ca-ion electrochemical systems have been pushed to the forefront of recent multivalent energy storage advances due to their use of earth-abundant redox materials and their high theoretical specific densities in relation to monovalent or even other more widely explored multivalent-charge carriers. However, significant pitfalls in metal plating and stripping arise from electrolyte decomposition and can be related to the coordination environment around Ca 2+ with both the negatively charged anion and the organic–aprotic solvent. Here, we apply multiple spectroscopic techniques in conjunction with density functional theory to evaluate the coordination environment of Ca 2+ across a class of ethereal solvents. Through the combination of X-ray absorption fine structure and time-dependent density functional theory, descriptive measures of the local geometry, coordination, and electronic structure of Ca–ethereal complexes provide distinct structural trends depending on the extent of the Ca 2+ –solvent interaction. Finally, we correlate these findings with electrochemical measurements of calcium tetrakis(hexafluoroisopropoxy)borate (CaBHFIP 2 ) salts dissolved within this class of solvents to provide insight into the preferred structural configuration of Ca 2+ electrolytic solutions for optimized electrochemical plating and stripping.

25 ENERGY STORAGE↗
DOE OSTI2021

Improved Low Temperature Performance of Graphite/Li Cells Using Isoxazole as a Novel Cosolvent in Electrolytes

An investigation of novel electrolyte formulations to improve low temperature performance of Li/graphite half cells has been conducted. A novel electrolyte co-solvent, isoxazole (IZ), has been investigated in electrolyte systems composed of lithium difluoro(oxalato)borate (LiDFOB) in fluoroethylene carbonate (FEC) and LiDFOB in ethylene carbonate (EC). Cells containing 1 M LiDFOB FEC: IZ electrolyte have a significant improvement in capacity retention and reversible capacity at −10 °C. Ex-situ surface analysis of the cycled electrodes suggests that reduction of LiDFOB results in an oxalate rich solid electrolyte interphase (SEI). Addition of FEC, results in improved stability of the anode SEI preventing further decomposition of isoxazole solvent and improving cycling performance.

25 ENERGY STORAGE↗
DOE OSTI2022

Performance of a Novel In-Situ Converted Additive for High Voltage Li-ion Pouch Cells

In search for new classes of additives for high voltage NMC/graphite lithium-ion cells, the precursor additive bis(trimethylsilyl) malonate (bTMSM) is shown to be activated via a spontaneous reaction with LiPF 6 and LiBF 4 salts in carbonate-based electrolyte to form lithium tetrafluoro(malonato)phosphate (LiTFMP), and lithium difluoro(malonato)borate (LiDFMB), respectively. The reaction schemes and rates were studied via NMR spectroscopy and GCMS. The effects of LiTFMP and LiDFMB on high voltage electrochemical performance were then examined up to 4.5 V in Li[Ni 0.4 Mn 0.4 Co 0.16 ]O 2 (NMC442)/graphite and Li[Ni 0.6 Mn 0.4 Co 0.0 ]O 2 (NMC/640)/graphite pouch cells using aggressive voltage-hold cycling, long-term charge/discharge cycling, storage experiments, electrochemical impedance spectroscopy, and gas evolution measurements. While in situ converted additives suffer from gassing issues due to the presence of trimethylfluorosilane (TMSF) gas, a side product of the in situ reaction of bTMSM with LiPF 6 , the cycling and storage capability for the activated additives under study shows competitive performance and controlled impedance when compared to other well-known high voltage additives. Micro X-ray fluorescence spectroscopy (μXRF) confirmed that LiTFMP successfully minimizes the rate of transition metal deposition on the surface of graphite apparently by forming a protective agent at the cathode surface, hence allowing for improved cycling performance at high voltages.

25 ENERGY STORAGE↗
DOE OSTI2022

Use of Ethylene Carbonate Free Ester Solvent Systems with Alternative Lithium Salts for Improved Low-Temperature Performance in NCM622∣∣ Graphite Li-ion Batteries

An investigation of alternative lithium salts, lithium tetrafluoroborate (LiBF 4 ), lithium difluoro(oxalato)borate (LiDFOB) and lithium hexafluorophosphate (LiPF 6 ), in novel ester-based (methyl acetate/fluoroethylene carbonate- MA/FEC or methyl propionate/fluoroethylene carbonate- MP/FEC) electrolyte formulations has been conducted in LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622)/graphite cells to improve low temperature cycling performance of lithium ion batteries at −20 °C. Improved low temperature performance was observed with all the lithium salts in MA/FEC electrolyte while comparable room temperature (25 °C) capacities were observed with LiPF 6 salt only. Detailed ex-situ analysis of surface films generated with LiBF 4 , LiDFOB and LiPF 6 in ester-based electrolytes reveals that the solid electrolyte interphase (SEI) is predominately composed of lithium salt decompaction products and addition of 10% FEC (by volume%) may not be sufficient at forming a protective SEI.

25 ENERGY STORAGE↗
DOE OSTI2022

Performance Improvement of Lithium Metal Batteries Enabled By LiBF 3 CN as a New Electrolyte Additive

A newly synthesized electrolyte additive, lithium trifluoro(cyano) borate (LiBF 3 CN), has been investigated for electrochemical performance improvement of lithium metal batteries. The LiBF 3 CN has a structure where one fluorine atom of BF 4 – is substituted with a cyano group (–CN) prepared by the reaction of boron trifluoride etherate with lithium cyanide. The electrochemical performance in symmetric Li/Li cells and NCM523/Li cells is significantly improved upon the incorporation of LiBF 3 CN as an electrolyte additive into a carbonate-based electrolyte. Extensive characterization of the deposited lithium metal reveals that a thin (≈20 nm) and robust SEI composed of LiN x O y , Li 3 N and Li 2 O is formed by the reductive decomposition of the LiBF 3 CN additive, which plays an important role in decreasing the resistance and stabilizing lithium deposition/stripping. The insight into the substitution effect of a functional group obtained from this work provides guidance for the design of new electrolyte additives.

25 ENERGY STORAGE↗
DOE OSTI2023

Improved Performance of Silicon-Containing Anodes with Organic Solvent-Solubilized Lithium Nitrate

Three different organic solvents (dimethylacetamide (DMAc), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO)) were used to improve the solubility of LiNO 3 in a standard carbonate-based electrolyte with lithium difluoro(oxalato)borate (LiDFOB) as the salt. Together, the LiDFOB and organic-solvent solubilized LiNO 3 preferentially reduce on the surface of silicon-containing anodes to create an SEI rich in oxalates, nitrate decomposition species, and B-F species. The improved stability of the SEI throughout the first 100 cycles results in silicon and silicon/graphite composite anodes with better capacity retention than observed with standard electrolytes or fluoroethylene carbonate (FEC) containing electrolytes. This study demonstrates the feasibility of the use of non-traditional electrolyte solvents in the improvement and optimization of lithium ion-battery electrolytes.

25 ENERGY STORAGE↗
DOE OSTI2024

Succinonitrile-Lithium Salt Complexes as Solid Catholytes for LLZO-Based Solid-State Batteries

The thermal and electrochemical properties of several succinonitrile (SN)-based organic ionic plastic crystals (OIPCs) containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalate) borate (LiBOB) or mixtures of the two salts, were investigated with the goal of determining which is most promising for use as a catholyte in solid-state lithium batteries. The best combination of properties for this use was found for the mixture containing 3 mol% LiTFSI and 2 mol% LiBOB in SN. Based on these observations, several solid-state cells containing Al-substituted Li 7 La 3 Zr 2 O 12 separators with composite cathodes consisting of LiNi 0.33 Mn 0.33 Co 0.33 O 2 (NMC111), carbon black, and the succinonitrile-salt mixtures were assembled and cycled at room temperature, without exogenous pressure, using a simple design.

25 ENERGY STORAGE↗
DOE OSTI2026

Quantifying SEI Reaction Rate in the Presence and Absence of Mn 2+

In this work, a methodology utilizing potentiostatic holds is developed for measuring side-reaction rates at graphite (Gr) electrodes. The influence of Mn 2+ on parasitic reactions is evaluated in the presence of various preformed solid-electrolyte interphases (SEI). Gr SEI preformation was carried out using vinylene carbonate (VC) or lithium difluoro(oxalato)borate (LiDFOB) as an additive. In addition, a highly fluorinated electrolyte, free of traditional non-fluorinated organic carbonates, was used. Parasitic current increases were observed for all preformed Gr SEIs when Mn 2+ was present. Of the preforming electrolytes, the VC-derived SEI showed the lowest parasitic currents both with and without Mn 2+ .

Tornheim, Adam [Argonne National Laboratory (ANL),↗
DOE OSTI2019

Advancing Lithium- and Manganese-Rich Cathodes through a Combined Electrolyte Additive/Surface Treatment Strategy

Lithium- and manganese-rich (LMR) materials provide cost and environmental advantages to other competing cathodes based on nickel or cobalt chemistries. Within the LMR family, layered-layered-spinel (LLS) cathodes have unique properties, detailed herein, that address several of the challenges faced in large-scale implementation of LMR cathodes. This paper details how a LLS//graphite system was considerably improved by combining optimization strategies. First, a cathode surface-treatment process was optimized. Interestingly, cathodes surface-treated at a low temperature (similar to 100 degrees C) exhibited the best results. The optimized LLS cathode was tested vs. graphite using small amounts of lithium difluoro(oxalate)borate electrolyte additive. The combined approach improved various aspects of the electrochemical performance (e.g., impedance, cycle life, and coulombic efficiency) more than each strategy used alone by mitigating Mn dissolution from the cathode and the ensuing deposition on the anode. The report describes a unique method to improve the performance of practically relevant LMR//graphite cells.

25 ENERGY STORAGE↗
DOE OSTI2019

Simultaneous upgrading of biomass-derived sugars to HMF/furfural via enzymatically isomerized ketose intermediates

Abstract Background Recently, exploring fermentative or chemical pathways that convert biomass-derived sugars to fuels/chemicals has attracted a lot of interest from many researchers. We are investigating a hydrocarbon pathway from mixed sugars via 5-hydroxymethyl furfural (HMF) and furfural intermediates. To achieve this goal, we must first convert glucose and xylose to HMF and furfural in favorable yields. Current processes to produce HMF/furfural generally involve the use of acid catalysts in biphasic systems or solvents such as ionic liquids. However, the yield from transforming glucose to HMF is lower than the yield of furfural from xylose. Results In this study, we present an efficient chemical pathway simultaneously transforming glucose and xylose to HMF and furfural via ketose intermediates, i.e., fructose and xylulose, which were generated from glucose and xylose via enzymatic isomerization. In the enzymatic isomerization, by adding sodium borate to complex with the ketoses, xylose conversion reached equilibrium after 2 h with a conversion of 91% and glucose conversion reached 84% after 4 h. By enzymatically isomerizing the aldoses to ketoses, the following dehydration reactions to HMF and furfural could be performed at low process temperatures (i.e., 110–120 °C) minimizing the side reactions of the sugars and limiting the degradation of furfurals to humins and carboxylic acids. At 120 °C, pH 0.5, and 15 min reaction time, mixed ketose sugars were converted to HMF and furfural in yields of 77% and 96%, respectively (based on starting aldose concentrations). Conclusion Taken together, our results demonstrate that this combined biological and chemical process could be an effective pathway to simultaneously convert biomass-derived glucose and xylose to HMF and furfural, for use as intermediates in the production of hydrocarbons.

09 BIOMASS FUELS↗
DOE OSTI2017

Corrosion Resistance of Amorphous Fe 49.7 Cr 17.7 Mn 1.9 Mo 7.4 W 1.6 B 15.2 C 3.8 Si 2.4 Coating: A New Criticality Control Material

Here, an iron-based amorphous metal with good corrosion resistance and a high absorption cross section for thermal neutrons has been developed and is reported here. This amorphous alloy has the approximate formula Fe 49.7 Cr 17.7 Mn 1.9 Mo 7.4 W 1.6 B 15.2 C 3.8 Si 2.4 and is known as SAM2X5. Chromium, molybdenum, and tungsten were added to provide corrosion resistance, while boron was added to promote glass formation and the absorption of thermal neutrons. Since this amorphous metal has a higher boron content than conventional borated stainless steels, it provides the nuclear engineer with design advantages for criticality control structures with enhanced safety. While melt-spun ribbons with limited practical applications were initially produced, large quantities (several tons) of gas-atomized powder have now been produced on an industrial scale, and applied as thermal-spray coatings on prototypical half-scale spent-nuclear-fuel containers and neutron-absorbing baskets. These prototypes and other SAM2X5 samples have undergone a variety of corrosion testing, including both salt-fog and long-term immersion testing. Modes and rates of corrosion have been determined in various relevant environments and are reported here. While these coatings have less corrosion resistance than melt-spun ribbons and optimized coatings produced in the laboratory, substantial corrosion resistance has been achieved.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Quantum ghost imaging microscopy depth-of-field study

Quantum ghost imaging approaches have been proposed to enhance biological microscopy, for example, using 2D visible detectors to provide IR images or providing additional dimensions of spatial or spectral information. Toward the goal of making such imaging schemes practical, we compare image quality and depth-of-field between traditional images and ghost images at the same excitation levels. We measure how image quality and depth-of-field depend on the parameters of the entangled light produced using type-I spontaneous parametric down-conversion (SPDC). We use a pair of time-synchronized, photon-timing single-photon avalanche diode (SPAD) array detectors to capture two distinct microscope imaging paths simultaneously on a photon-pair-by-photon-pair basis: one in a traditional imaging pathway and the other a quantum ghost imaging pathway. We calculate the depth-of-field, resolution, contrast, and signal-to-noise ratio (SNR) through the parameter space of a β-Barium Borate (BBO) type-I bulk non-linear crystal length and angle. Our results provide a basis for choosing parameters for quantum ghost imaging with type-I SPDC sources.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Interrelationship of Thermal Effects on Calcium Sulfate Dihydrate Casts Containing Borax and Kaolin: Differential Thermal Analysis (DTA), Thermogravimetric Analysis (TGA), and Contact Dilatometry

The core composition of gypsum wallboard is calcium sulfate dihydrate (CaSO 4 ·2H 2 O) with varying impurities, additives, or both. This study compares here two commercially calcined sources of hemihydrate (CaSO 4 ·½H 2 O) from a natural source and a synthetic by-product of flue gas desulfurization and neutralization to reagent grade hemihydrate. Two common ingredients, borax and kaolin, are mixed into a slurry with distilled water. The analysis supports the hypothesis that minor components in the cast have an effect on the high temperature performance of gypsum casts. The analysis is enhanced when the differential thermal analysis, thermogravimetric analysis, and dilatometry data are combined to study the changes in density versus heat flow. Specifically, the thermal performance is affected by (1) the impurities found in hemihydrate sources; (2) during the fluidization phase, the reaction of borax with free Ca ++ ions to form new borate salts that melt at lower temperatures; and (3) the intercalation of these and other ions with kaolin, providing thermal stability by reducing the formation of thermally active salts.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Structural Characterization of Ternary Salt Melts for Low Activity Waste Applications

Reactions of alkali salts (nitrates, sulfates, carbonates, halides, borates) play a key role in the low temperature feed conversion occurring at the cold cap during processing of Hanford Low Activity Waste (LAW) glass melters. An alkali salt phase can sometimes form, and preferentially incorporate radionuclides of Cs, Cl, I, and Tc. During melting of the slurry feed, some of the feed components sequentially break down with increasing temperature to form gases (i.e., nitrates → NO x , carbonates → CO 2 , and boric acid → H 2 O) or partially volatilize (halides). Sulfate, however, tends not to volatilize but has limited solubility in the final borosilicate glass waste form. To improve understanding of these low temperature processes and their composition dependencies, a scoping study was undertaken to synthesize salt systems that remain amorphous at room temperature, thus facilitating structural study. Melts of equimolar ratios of K2SO4-ZnSO4 (a known ionic glass-forming system) with added nitrates, halides, or carbonates, were melted and quenched. Some of the materials formed single phase glasses and some underwent crystallization upon quenching. Characterization of these quenched materials by thermal analysis, infrared absorption, and diffraction was performed. Addition of other anions to the sulfate base glass resulted in a distortion of the sulfate tetrahedron, as evidenced by infrared absorption. Carbonates strongly promoted crystallization, mostly of carbonate phases. Nitrates promoted crystallization of ZnO, and the nitrate volatilized with some incorporating into the glass. Here, halides tended to incorporate into the glass, but the small (F) and large (I) halogens promoted crystallization of sulfate-containing crystals, while moderate sized (Cl) halogens produced single-phase ionic glasses.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Materials Data on BH9(CO)3 by Materials Project

B(OCH3)3 crystallizes in the hexagonal P6_3/m space group. The structure is zero-dimensional and consists of two trimethyl borate molecules. B3+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All B–O bond lengths are 1.38 Å. C2- is bonded in a tetrahedral geometry to three H1+ and one O2- atom. All C–H bond lengths are 1.10 Å. The C–O bond length is 1.44 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. O2- is bonded in a bent 120 degrees geometry to one B3+ and one C2- atom.

36 MATERIALS SCIENCE↗