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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Extremely Stable Sodium Metal Batteries Enabled by Localized High-Concentration Electrolytes

Sodium (Na) metal is a promising anode for Na ion batteries. However, the high reactivity of Na metal with electrolytes and the low Na metal cycling efficiency have limited its practical application in rechargeable Na metal batteries. High concentration electrolytes (HCE, ≥4 M) consisting of sodium bis(fluorosulfonyl)imide (NaFSI) and ether solvent could ensure the stable cycling of Na metal with high coulombic efficiency, but suffer from high viscosity, poor wetting ability, and high salt cost. Here, we report that the salt concentration could be significantly reduced (≤ 1.5 M) by diluting with a hydrofluoroether (HFE) as ‘inert’ diluent, which maintains the solvation structures of HCE, thereby forming a localized high concentration electrolyte (LHCE). A LHCE (2.1 M NaFSI/DME-BTFE (solvent molar ratio 1:2)) has been demonstrated to enable the dendrite-free Na deposition with high coulombic efficiency of > 99%, fast-charging (20C) and stable cycling (90.8% retention after 40,000 cycles) of Na||Na3V2(PO4)3 batteries.

concentrated electrolyte↗
DOE OSTI2021

Origins of Lithium/Sodium Reverse Permeability Selectivity in 12-Crown-4-Functionalized Polymer Membranes

Direct lithium extraction via membrane separations has been fundamentally limited by lack of monovalent ion selectivity exhibited by conventional polymeric membranes, particularly between sodium and lithium ions. Recently, a 12- Crown-4-functionalized polynorbornene membrane was shown to have the largest lithium/sodium permeability selectivity observed in a fully aqueous system to date. Using atomistic molecular dynamics simulations, we reveal that this selectivity is due to strong interactions between sodium ions and 12-Crown-4 moieties, which reduce sodium ion diffusivity while leaving lithium ion mobility relatively unaffected. Furthermore, the ion diffusivities in the membrane, when scaled by their respective solution diffusivities and free ion fractions, can be collapsed to an almost universal relationship depending on solvent volume fraction.

36 MATERIALS SCIENCE↗
DOE OSTI2014

X-ray absorption spectroscopy of LiBF 4 in propylene carbonate. A model lithium ion battery electrolyte

Since their introduction into the commercial marketplace in 1991, lithium ion batteries have become increasingly ubiquitous in portable technology. Nevertheless, improvements to existing battery technology are necessary to expand their utility for larger-scale applications, such as electric vehicles. Advances may be realized from improvements to the liquid electrolyte; however, current understanding of the liquid structure and properties remains incomplete. X-ray absorption spectroscopy of solutions of LiBF 4 in propylene carbonate (PC), interpreted using first-principles electronic structure calculations within the eXcited electron and Core Hole (XCH) approximation, yields new insight into the solvation structure of the Li + ion in this model electrolyte. By generating linear combinations of the computed spectra of Li + -associating and free PC molecules and comparing to the experimental spectrum, we find a Li + –solvent interaction number of 4.5. This result suggests that computational models of lithium ion battery electrolytes should move beyond tetrahedral coordination structures.

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

Field electron emission from pencil-drawn cold cathodes

Field electron emitters with flat, curved, and linear profiles are fabricated on flexible copy papers by direct pencil-drawing method. This one-step method is free of many restricted conditions such as high-temperature, high vacuum, organic solvents, and multistep. The cold cathodes display good field emission performance and achieve high emission current density of 78 mA/cm{sup 2} at an electric field of 3.73 V/μm. The approach proposed here would bring a rapid, low-cost, and eco-friendly route to fabricate but not limited to flexible field emitter devices.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Solution-Grown Rubrene Crystals as Radiation Detecting Devices

There has been increased interest in organic semiconductors over the last decade because of their unique properties. Of these, 5, 6, 11, 12-tetraphenylnaphthacene (rubrene) has generated the most interest because of its high charge carrier mobility. In this paper, large single crystals with a volume of ~1 cm 3 were grown from solution by a temperature reduction technique. The faceted crystals had flat surfaces and cm-scale, visually defect-free areas suitable for physical characterization. X-ray diffraction analysis indicates that solvent does not incorporate into the crystals and photoluminescence spectra are consistent with pristine, high-crystallinity rubrene. Furthermore, the response curve to pulsed optical illumination indicates that the solution grown crystals are of similar quality to those grown by physical vapor transport, albeit larger. The good quality of these crystals in combination with the improvement of electrical contacts by application of conductive polymer on the graphite electrodes have led to the clear observation of alpha particles with these rubrene detectors. Finally, preliminary results with a 252 Cf source generate a small signal with the rubrene detector and may demonstrate that rubrene can also be used for detecting high-energy neutrons.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Conceptual Basis and Techno-Economic Modeling for Integrated Algal Biorefinery Conversion of Microalgae to Fuels and Products (2019 NREL TEA Update: Highlighting Paths to Future Cost Goals via a New Pathway for Combined Algal Processing)

The report documents the conceptual basis for a new potential Combined Algal Processing design strategy which may allow more flexibility in accommodating different algal biomass feedstock compositions, by enabling upgrading of both protein and carbohydrates in a single step, without a strict requirement for either component to be in soluble or monomeric form, while maintaining effective wet lipid extraction techniques to enable high lipid recoveries. In light of previously-established constraints around algal biomass costs (which are significantly higher than lignocellulosic terrestrial biomass), the present CAP processing strategy reflects an integrated biorefinery concept producing both fuels and value-added chemical coproducts as a means to improve profitability and generate coproduct revenues to help drive down the minimum fuel selling price (MFSP) towards economically viable levels. Namely, this report highlights an integrated CAP biorefinery process and associated technical targets that would be required to achieve U.S. Department of Energy target MFSP goals of $2.5/gallon gasoline equivalent by 2030. This is accomplished by a process involving low-cost seasonal storage of algal biomass during high-growth seasons, rapid flash hydrolysis pretreatment of the biomass, solvent extraction of pretreated biomass, cleanup and fractionation of lipids into triglyceride and free fatty acid fractions, and a series of thermochemical conversion steps to upgrade carbohydrates and protein to hydrocarbon fuels. These steps include mild oxidative treatment (MOT), a process originally investigated at NREL for upgrading lignin, followed by catalytic ketonization and hydrotreating of MOT products to fuels. Isolated triglycerides are sent to a coproduct train, with the base case focused on upgrading to polyurethane foams as a high-value, high-market-volume coproduct.

09 BIOMASS FUELS↗
NASA NTRS1986

MAPM: A coherent dual CO2 laser DIAL system

The Mobile Atmospheric Pollutant Mapping System (MAPM) is a dual CO2 laser DIAL system with heterodyne detection that is being developed for large distance range resolved measurement of organic solvent vapors and aerosol clouds. The components have been chosen to allow measurements to be made to distances of 6 to 7 km in a period of 20 to 30 s. The major components of the system are listed. MAPM is being integrated into a system and will be tested with several organic solvent gases and vapors in a remotely positioned sample chamber and with a free release of ethylene. Experimental results and system performance are discussed.

Grant, W. B.↗
DOE OSTI2020

Method to produce colorless, high porosity, transparent polymer aerogels

A method to produce a polymer gel includes dissolving precursors in a solvent to form a precursor solution, the precursors including polymer precursors, a stable free radical, one or more initiating radicals, and one or more stable free radical control agents, and heating the precursor solution to a temperature of polymerization to produce a cross-linked gel. A dried polymer aerogel has a Brunauer-Emmett Teller (BET) surface area over 100 m2/g, porosity of greater than 10%, visible transparency greater than 20%, color rendering index of over 20%, and average pore size of less than 100 nm.

Chintapalli, Mahati↗
DOE OSTI2022

Oil and water resistant low adhesion surface treatment and coatings

A novel omniphobic surface coating is disclosed that provides both high oil-repellency and high-water repellency to the coated surface. The coating may contain perfluoropolyether (PFPE) or a similar fluorinated or perfluorinated polymer, as well as a hardener and a catalyst. One or more surfactants or viscosifiers may also be added. Further, the coating may contain one or more functional additives, including, but not limited to, coloring agents, anti-corrosive agents, anti-fouling agents, water-repellent agents, and/or oil-repellent agents. Methods for formulating the novel omniphobic surface coating are also described. Such methods include preparing a first part of the coating, which may contain, at minimum, a polymer such as PFPE or a similar fluorinated or perfluorinated polymer, and a suitable solvent; preparing a second part of the coating, which is a water-free system that may contain, at minimum, a hardener and a catalyst; and combining the first part and the second part together.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Formation of Reversible Solid Electrolyte Interface on Graphite Surface from Concentrated Electrolytes

Interfacial phenomena have always been key determinants for the performance of energy storage technologies. The solid electrolyte interfacial (SEI) layer, pervasive on the surfaces of battery electrodes for numerous chemical couples, directly affects the ion transport, charge transfer and lifespan of the entire energy system. Almost all SEI layers, however, are unstable resulting in the continuous consumption of the electrolyte. Typically, this leads to the accumulation of degradation products on/restructuring of the electrode surface and thus increased cell impedance, which largely limits the long-term operation of the electrochemical reactions. Herein, a completely new SEI formation mechanism has been discovered, in which the electrolyte components reversibly self-assemble into a protective surface coating on a graphite electrode upon changing the potential. In contrast to the established wisdom regarding the necessity of employing the solvent ethylene carbonate (EC) to form a protective SEI layer on graphite, a wide range of EC-free electrolytes are demonstrated for the reversible intercalation/deintercalation of Li+ cations within a graphite lattice, thereby providing tremendous flexibility in electrolyte tailoring for battery couples. This novel finding is broadly applicable and provides guidance for how to control interfacial reactions through the relationship between ion aggregation and solvent decomposition at polarized interfaces.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2019

Application of the ESMACS Binding Free Energy Protocol to a Multi-Binding Site Lactate Dehydogenase A Ligand Dataset

Over the past two decades, the use of fragment-based lead generation has become a common, mature approach to identify tractable starting points in chemical space for the drug discovery process. This approach naturally involves the study of the binding properties of highly heterogeneous ligands. Such datasets challenge computational techniques to provide comparable binding free energy estimates from different binding modes. The performance of a range of statistically robust ensemble-based binding free energy calculation protocols, called ESMACS (enhanced sampling of molecular dynamics with approximation of continuum solvent), is evaluated. Ligands designed to target two binding pockets in the lactate dehydogenase, a target protein, which vary in size, charge, and binding mode, are studied. When compared to experimental results, excellent statistical rankings are obtained across this highly diverse set of ligands. In addition, three approaches to account for entropic contributions are investigated: 1) normal mode analysis, 2) weighted solvent accessible surface area (WSAS), and 3) variational entropy. Normal mode analysis and WSAS correlate strongly with each other—although the latter is computationally far cheaper—but do not improve rankings. Variational entropy corrects exaggerated discrimination of ligands bound in different pockets but creates three outliers which reduce the quality of the overall ranking.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Syntheses, crystal structures and properties of series of 4d–4f ln(III)–Ag(I) heterometallic coordination polymers

By control of the experimental parameters such as ligands, pH value and reacting temperature, series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction, namely, ([Ln{sup III}Ag{sup I}(na)(ina)(ox)]·2(H{sub 2}O)){sub n} [Ln=Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Ho(6), Y(7), Yb(8)], have been successfully synthesized under hydrothermal conditions and structurally characterized. All the complexes are characterized by elemental analyses, FT-IR spectroscopy, Powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Furthermore, the luminescence properties of compounds 2 and 4 and the magsnetic properties of complexes 3 and 5 were also investigated in detail. - Graphical abstract: Series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction which are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. - Highlights: • Complexes 1–8 are first built by three kinds of organic ligands based on nicotinic acid and isonicotinic acid. • PCPs 1–8 are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. • The total solvent-accessible volume of PCP 2 comprises 11.6% of the crystal volume after dislodging the free water molecules. • Complexes 2 and 4 exhibit characteristic lanthanide-centered luminescence, while compounds 3 and 5 show antiferromagnetic behaviors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Electrocatalysis in CO 2 -Binding Organic Liquids with an Iron Porphyrin

Direct electrochemical upgrading of CO 2 in capture media is an attractive approach to carbon capture that can bypass the energy requirement for the thermal release of pure CO 2 . Here we investigate the electrocatalytic activity of iron(tetraphenylporphyrin) in the presence of organic solvents that convert into ionic liquids upon exposure to CO 2 . Four different solvent systems were tested, all of which capture CO 2 in the form of an alkyl carbonate (or carbamate) anion and an acidic ammonium cation. The electrocatalytic selectivity exhibited a strong dependence on the acidity of the capture medium, with the most basic solvent affording a high selectivity for production of CO instead of H 2 . Experimental and computational studies support a canonical mechanism in which the catalyst reacts with free CO 2 in solution, as opposed to a reaction with the alkyl carbonate that is present in high concentration. Kinetic analysis indicates that the rate-limiting step is changed from C–O protonolysis in traditional solvents to the binding of CO 2 in the capture media. Quantitative 13 C– 13 C EXSY revealed that the dissociation of the alkyl carbonate into free, solvated CO 2 is very rapid (~15 s –1 ) compared to the interconversion of HCO 3 – /CO 2 in aqueous solution. These results underscore the need to understand the mechanism and kinetics for both the release of captured CO 2 and its electrocatalytic conversion.

Carbon Dioxide↗
DOE OSTI2016

The radiolysis of CMPO: effects of acid, metal complexation and alpha vs. gamma radiation

Abstract The group actinide/lanthanide complexing agent octylphenylcarbamoylmethyl phosphine oxide (CMPO) has been examined for its radiation stability by measuring the kinetics of its reactions with free radicals in both the aqueous and organic phases for the free and metal-complexed ligand, identifying its degradation products for both alpha and gamma irradiation, measuring the effects on solvent extraction performance, and measuring the G-values for its degradation under various conditions. This includes the G-values for CMPO in the absence of, and in contact with the acidic aqueous phase, where it is shown that the acidic aqueous phase provides radio-protection for this ligand. It was found that both solvent and metal complexation affect the kinetics of the reaction of the •NO3 radical, a product of HNO3 radiolysis, with CMPO. For example, CMPO complexed with lanthanides has a rate constant for this reaction an order of magnitude higher than for the free ligand, and the reaction for the free ligand in the organic phase is about three times faster than in the aqueous phase. In steady state radiolysis kinetics it was determined that HNO3, although not NO3- anion, provides radio-protection to CMPO, with the G-value for its degradation decreasing with increasing acidity, until it was almost completely suppressed by irradiation in contact with 5 M HNO3. The same degradation products were produced by irradiation with alpha and gamma-sources, except that the relative abundances of these products varied. For example, the product of C-C bond scission was produced only in low amounts for gamma-radiolysis, but it was an important product for samples irradiated with a He ion beam. These results are compared to the new data appearing in the literature on DGA radiolysis, since CMPO and the DGAs both contain the amide functional group.

CMPO↗
DOE OSTI2018

Mesoscopic Structure Facilitates Rapid CO 2 Transport and Reactivity in CO 2 Capture Solvents

ABSTRACT: We present two-dimensional (2D) and three-dimensional (3D) chemical speciation of a switchable ionic liquid CO2 capture solvent to asses how these fluids facilitate CO2 transport at high solution viscosities. In this study, we use in situ liquid time-of-flight secondary ion mass spectrometry (ToF-SIMS) enabled by a vacuum-compatible microreactor. SIMS spectra show the existence of 1-((1,3-dimethylimidazolidin-2-ylidene)amino)propan-2-ol (IPADM-2-BOL) and CO2 + IPADM-2-BOL, con-firming the proposed zwitterionic CO2 binding mechanism. 2D and 3D chemical mapping showed IPADM-2-BOL exhibited a heterogeneous molecular structure, with regions of CO2-free IPADM-2-BOL coexisting with clusters of zwitterionic carbonate ions (IPADM-2-BOL + CO2). The solvent was composed of ~10–20 nm clusters of zwitterionic carbonate ions at any CO2 loading above 0%. The size of clusters was found not to grow with CO2 loading; rather, the concentration and distribution of clusters in-creased. 2D measurements also confirmed that the small clusters of bound CO2 aggregate in solution, coalescing to form >500 nm aggregates, and concurrently creating regions of unreacted solvent where CO2 can readily diffuse and immediately eact. The het-erogeneous domains introduce a trade-off between rapid CO2 diffusion and reactivity at the expense of a high solution viscosity.

Yu, Xiao-Ying↗
DOE OSTI2014

Diffusional motion of redox centers in carbonate electrolytes

Ferrocene (Fc) and N-(ferrocenylmethyl)-N,N-dimethyl-N-ethylammonium bistrifluoromethyl-sulfonimide (Fc1N112-TFSI) were dissolved in carbonate solvents and self-diffusion coefficients (D) of solutes and solvents were measured by {sup 1}H and {sup 19}F pulsed field gradient nuclear magnetic resonance (NMR) spectroscopy. The organic solvents were propylene carbonate (PC), ethyl methyl carbonate (EMC), and a ternary mixture that also includes ethylene carbonate (EC). Results from NMR studies over the temperature range of 0–50 °C and for various concentrations (0.25–1.7 M) of Fc1N112-TFSI are compared to values of D simulated with classical molecular dynamics (MD). The measured self-diffusion coefficients gradually decreased as the Fc1N112-TFSI concentration increased in all solvents. Since TFSI{sup −} has fluoromethyl groups (CF{sub 3}), D{sub TFSI} could be measured separately and the values found are larger than those for D{sub Fc1N112} in all samples measured. The EC, PC, and EMC have the same D in the neat solvent mixture and when Fc is dissolved in EC/PC/EMC at a concentration of 0.2 M, probably due to the interactions between common carbonyl structures within EC, PC, and EMC. A difference in D (D{sub PC} < D{sub EC} < D{sub EMC}), and both a higher E{sub a} for translational motion and higher effective viscosity for PC in the mixture containing Fc1N112-TFSI reflect the interaction between PC and Fc1N112{sup +}, which is a relatively stronger interaction than that between Fc1N112{sup +} and other solvent species. In the EC/PC/EMC solution that is saturated with Fc1N112-TFSI, we find that D{sub PC} = D{sub EC} = D{sub EMC} and Fc1N112{sup +} and all components of the EC/PC/EMC solution have the same E{sub a} for translational motion, while the ratio D{sub EC/PC/EMC}/D{sub Fc1N112} is approximately 3. These results reflect the lack of available free volume for independent diffusion in the saturated solution. The Fc1N112{sup +} transference numbers lie around 0.4 and increase slightly as the temperature is increased in the PC and EMC solvents. The trends observed for D from simulations are in good agreement with experimental results and provide molecular level understanding of the solvation structure of Fc1N112-TFSI dissolved in EC/PC/EMC.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Ion Association in AlCl3 Aqueous Solutions from Constrained First-Principles Molecular Dynamics

Ab initio molecular dynamics was used to investigate the ion pairing behavior between Cl- and the Al3+ ion in an aqueous AlCl3 solution containing 63 water molecules. A series of constrained simulations was carried out at 300 K for up to 16 ps each, by fixing the inter-nuclear separation (rAl-Cl) between the Al3+ ion and one of the Cl- ions. The calculated potential of mean force of the Al3+-Cl- ion pair shows a pronounced minimum at rAl-Cl = 2.3 Å corresponding to a contact ion pair (CIP). Two local minima assigned to solvent separated ion pairs (SSIP) are identified at rAl-Cl= 4.4 and 6.0 Å. The positions of the free energy minima coincide with the hydration shell intervals of the Al3+ cation suggesting that the Cl- ion is inclined to reside in regions of low concentration of waters, i.e. between the 1st and 2nd shells of Al3+ and between the 2nd shell and bulk. A detailed analysis of solvent structure around the Al3+ and Cl- ions as a function of rAl-Cl is presented. The results are compared to structure data from X-ray measurements and unconstrained AIMD simulations of single ions Al3+ and Cl- and AlCl3 solutions. The dipole moment of the water molecules inside the 1st and 2nd hydration shells of Al3+ and in the bulk region and those of the Clion were calculated as a function of rAl-Cl. Major changes in the electronic structure of the system result from the removal of Cl- from the 1st hydration shell of the Al3+ cation. Finally, two unconstrained AIMD simulations of aqueous AlCl3 solutions corresponding to CIP and SSIP configurations were performed (17 ps, 300 K). Only minor structural changes are observed in these systems, confirming their stability.

ab initio↗
DOE OSTI2014

Electrostatics of proteins in dielectric solvent continua. II. Hamiltonian reaction field dynamics

In Paper I of this work [S. Bauer, G. Mathias, and P. Tavan, J. Chem. Phys. 140, 104102 (2014)] we have presented a reaction field (RF) method, which accurately solves the Poisson equation for proteins embedded in dielectric solvent continua at a computational effort comparable to that of polarizable molecular mechanics (MM) force fields. Building upon these results, here we suggest a method for linearly scaling Hamiltonian RF/MM molecular dynamics (MD) simulations, which we call “Hamiltonian dielectric solvent” (HADES). First, we derive analytical expressions for the RF forces acting on the solute atoms. These forces properly account for all those conditions, which have to be self-consistently fulfilled by RF quantities introduced in Paper I. Next we provide details on the implementation, i.e., we show how our RF approach is combined with a fast multipole method and how the self-consistency iterations are accelerated by the use of the so-called direct inversion in the iterative subspace. Finally we demonstrate that the method and its implementation enable Hamiltonian, i.e., energy and momentum conserving HADES-MD, and compare in a sample application on Ac-Ala-NHMe the HADES-MD free energy landscape at 300 K with that obtained in Paper I by scanning of configurations and with one obtained from an explicit solvent simulation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗