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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Impacts of Guanidine Degradation Products on Next Generation Solvent (NGS) Caustic Side Solvent Extraction (CSSX) Processing

Savannah River National Laboratory researchers have been requested to perform testing to assess the potential for build-up of guanidine degradation compounds in the Next Generation Solvent Caustic Side Solvent Extraction process. Testing was also requested to determine the impact of guanidine degradation compounds [3,7-dimethyloctylamine (iDA) and Bis-N,N’-(3,7-dimethyloctyl)urea (DiDU)] on cesium behavior in the flowsheet. Twelve partitioning experiments were performed to quantify the partitioning coefficient of identified guanidine degradation compounds in various organic-aqueous mixtures. Six Extraction, Scrub, and Strip (ESS) experiments were performed to quantify the impact of degradation products on cesium behavior.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Radiological Degradation of Tetraoctyl Diglycolamide in n-Alkyl Solvents: Influence of Solvent Ionization Potential

Reprocessing of used nuclear fuel reduces the requirements for long-term storage repositories. Cost-efficient processes depend on knowledge of radiation effects, but gaps occur in understanding how radiation results in the degradation of fuel separation molecules. This project investigates the influence of different n-alkyl solvents on the radiolytic fragmentation behavior of N,N,N',N'-Tetraoctyl-3-oxapentane-1,5-diamide (TODGA), a promising ligand for extraction of the lanthanides and minor actinides from dissolved nuclear fuel. Findings from this work suggest a linkage between the ionization potential of the solvent and the degradation products observed in the resulting mass spectrum.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Role of a Multivalent Ion–Solvent Interaction on Restricted Mg 2+ Diffusion in Dimethoxyethane Electrolytes

The diffusion behavior of Mg 2+ in electrolytes is not as readily accessible as that from Li + or Na + utilizing PFG NMR, due to the low sensitivity, poor resolution, and rapid relaxation encountered when attempting 25 Mg NMR. In MgTFSI 2 /DME solutions, “bound” DME (coordinating to Mg 2+ ) and “free” DME (bulk) are distinguishable from 1 H NMR. With the exchange rates between them obtained from 2D 1 H EXSY NMR, we can extract the self-diffusivities of free DME and bound DME (which are equal to that of Mg 2+ ) before the exchange occurs using PFG diffusion NMR measurements coupled with analytical formulas describing diffusion under two-site exchange. Further, the high activation enthalpy for exhange (65–70 kJ/mol) can be explained by the structural change of bound DME as evidenced by its reduced C–H bond length. Comparison of the diffusion behaviors of Mg 2+ , TFSI – , DME, and Li + reveals a relative restriction to Mg 2+ diffusion that is caused by the long-range interaction between Mg 2+ and solvent molecules, especially those with suppressed motions at high concentrations and low temperatures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Solvent-Cast Solid Electrolyte Membranes Based on a Charged Rigid-Rod Polymer and Ionic Liquids

Solid-state electrolytes are attractive for use in electrochemical devices because they remove the need for a flammable liquid electrolyte while contributing to the structural integrity of the device. We have recently developed a class of solid electrolytes, termed molecular ionic composites (MICs), composed of ionic liquids (ILs) and a rigid-rod polyelectrolyte, poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT). MIC materials, originally obtained through an ion-exchange process between IL and PBDT aqueous solution, possess an unprecedented combination of high ionic conductivity, high thermal stability, low flammability and widely tunable tensile storage moduli. Here we present a facile solvent casting method for preparing MIC membranes. These membranes are uniform, flexible, and tough, with tunable composition and thickness (≥ 40 μm). Unlike the previous ion-exchange method, which only allowed incorporation of hydrophilic ILs, we can now incorporate hydrophobic ILs to prepare MIC membranes for, e.g. battery electrolytes. A sodium (Na) metal symmetric cell constructed with a PBDT-Pyr 14 TFSI membrane as the solid electrolyte shows long-term stable cycling (> 500 h.) at 60 °C. Furthermore, the ability to prepare MICs using both hydrophilic and hydrophobic ILs initiates a wider range of MIC materials and broadens the array of applications accessible by MIC membranes.

25 ENERGY STORAGE↗
DOE OSTI2014

Solvent-Assisted Linker Exchange: An Alternative to the De Novo Synthesis of Unattainable Metal-Organic Frameworks

Metal-organic frameworks (MOFs) have gained considerable attention as hybrid materials—in part because of a multitude of potential useful applications, ranging from gas separation to catalysis and light harvesting. Unfortunately, de novo synthesis of MOFs with desirable function–property combinations is not always reliable and may suffer from vagaries such as formation of undesirable topologies, low solubility of precursors, and loss of functionality of the sensitive network components. The recently discovered synthetic approach coined solvent-assisted linker exchange (SALE) constitutes a simple to implement strategy for circumventing these setbacks; its use has already led to the generation of a variety of MOF materials previously unobtainable by direct synthesis methods. This Review provides a perspective of the achievements in MOF research that have been made possible with SALE and examines the studies that have facilitated the understanding and broadened the scope of use of this invaluable synthetic tool.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

In situ GISAXS study of a Si-containing block copolymer under solvent vapor annealing: Effects of molecular weight and solvent vapor composition

The room-temperature solvent vapor annealing of polystyrene-b-polydimethylsiloxane (PS-b-PDMS) block copolymer films was studied in situ by grazing incidence small-angle X-ray scattering. Films of cylinder-forming PS-b-PDMS with molecular weight 16 kg/mol and 12.2 kg/mol, annealed under vapors of toluene:heptane with varying composition, exhibited swelling-ratio-dependent evolution of microdomain spacing and orientation. In a vapor made from a toluene:heptane 5:1 volumetric ratio liquid mixture, or from pure toluene, cylindrical microdomains reoriented from majority out-of-plane to in-plane during annealing, while drying led to shrinkage along the film normal and a large distortion of the hexagonal lattice of in-plane cylinders. As a result, annealing under vapor from a toluene:heptane 1:5 volumetric ratio liquid produced a non-bulk lamellar structure in the 16 kg/mol PS-b-PDMS.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

Elucidating the Solvation Structure and Dynamics of Lithium Polysulfides Resulting from Competitive Salt and Solvent Interactions

Designing optimal electrolytes is key to enhancing the performance of energy storage devices,especially relating to cycle life, efficiency, and stability.1 Specifically, for future beyond-Li ion energy storage, there is still ample room for electrolyte improvements. Among the candidates for higher gravimetric energy storage, the Li-S battery is considered quite promising, owing to its theoretical specific energy density (2600 Wh/kg) and specific capacity (1675 mAh/g) and significantly lower cost as compared to state-of-art lithium-ion batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2021

The Deep Eutectic Solvent Precipitation Synthesis of Metastable Zn 4 V 2 O 9

A precipitation method involving a deep eutectic solvent (DES)–a mixture of hydrogen bond donor and acceptor–is used to synthesize a ternary metal oxide. Without toxic reagents, precipitates consisting of Zn 3 (OH) 2 V 2 O 7 ·nH 2 O and Zn 5 (OH) 6 (CO 3 ) 2 are obtained by simply introducing deionized H 2 O to the DES solution containing dissolved ZnO and V 2 O 5 . Manipulation of the synthetic conditions demonstrates high tunability in the size/morphology of the two-dimensional nanosheets precipitated during the dynamic equilibrium process. According to differential scanning calorimetry and high-temperature powder X-ray diffraction, Zn 3 V 2 O 8 and ZnO obtained by the annealing of the precipitate are intermediates in the reaction pathway toward metastable Zn 4 V 2 O 9 . Intimate mixing of the metal precursors achieved by the precipitation method allows access to the metastable zinc-rich vanadate with unusually rapid heat treatment. Furthermore, the UV–vis and surface photovoltage spectra reveal the presence of sub-band gap states, stemming from the reduced vanadium (V 4+ ) center. Photoelectrochemical measurements confirm weak photoanodic currents for water and methanol oxidation. For the first time, this work shows the synthesis of a metastable oxide with the DES-precipitation route and provides insight into the structure–property relationship of the zinc-rich vanadate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗