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At least 289 records · Page 16

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DOE OSTI2023

Interface-enhanced conductivities in surfactant-mediated, solution-grown ionic crystalline complexes

Renewable energy is increasingly relying on optimized electrolytes and interfaces. In this work, Tween 20 and sodium chloride are selected as a model system to reveal the effects of surfactants on salt crystallization in the context of ionic conductivity and interface optimization. At a varied crystallization speed and mix ratio, it is demonstrated that the resultant solution-grown ionic crystalline complexes can achieve a highly tunable ion transport with a controllable crystalline interface. X-ray diffraction results rule out the possibility of polymorphism in the NaCl/Tween 20 systems, which further supports the importance of an optimized crystalline network for optimizing permittivity or ionic conductivity. Raman mapping and machine learning techniques are used to perform semantic segmentation on highly heterogeneous NaCl/Tween 20 complexes. Furthermore, FTIR measurements demonstrate that inter- and intra-molecular interactions play critical roles in the formation of these crystals. This work lays a foundation toward future optimization of such complex ion systems for a specific salt or crystallization modifier in energy storage or ion transport applications.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Designing Imidazolium Poly(amide-amide) and Poly(amide-imide) Ionenes and Their Interactions with Mono- and Tris(imidazolium) Ionic Liquids

Here we introduce the synthesis and thermal properties of a series of sophisticated imidazolium ionenes with alternating amide-amide or amide-imide backbone functionality, and investigate the structural effects of mono(imidazolium) and unprecedented tris(imidazolium) ionic liquids (ILs) in these ionenes. The new set of poly(amide-amide) (PAA) and poly(amide-imide) (PAI) ionenes represent the intersection of conventional high-performance polymers with the ionene archetype–presenting polymers with alternating functional and ionic elements precisely sequenced along the backbone. The effects of polymer composition on the thermal properties and morphology were analyzed. Five distinct polymer backbones were synthesized and combined with a stoichiometric equivalent of the IL 1-benzyl-3-methylimidazolium bistriflimide ([Bnmim][Tf 2 N]), which were studied to probe the self-assembly, structuring, and contributions of intermolecular forces when IL is added. Furthermore, three polyamide (PA) or polyimide (PI) ionenes with simpler xylyl linkages were interfaced with [Bnmim][Tf 2 N] as well as a novel amide-linked tris(imidazolium) IL, to demonstrate the structural changes imparted by the inclusion of functional, ionic additives dispersed within the ionene matrix. This work highlights the possibilities for utilizing concepts from small molecules which exhibit supramolecular self-assembly to guide creative design and manipulate the structuring of ionenes.

36 MATERIALS SCIENCE↗

NASA NTRS1981

Ionic conductivity and thermoelectric power of pure and Al2O3-dispersed AgI

Ionic and electronic conductivities, and thermoelectric power have been measured for AgI and AgI containing a dispersion of submicron size Al2O3 particles. While the dispersion of Al2O3 enhances the ionic conductivity significantly, it does not affect the electronic properties of the matrix. The enhancement is a strong function of the size and concentration of the dispersoid. Various models have been tested to account for the enhanced conduction. However, the complex behavior of the present results points out the need for more sophisticated theoretical models. Ionic conduction and thermoelectric power data suggest that the dispersed Al2O3 generates an excess of cation vacancies and thereby enhances the conductivity and suppresses the thermoelectric power of the matrix. The individual heats of transport of cation interstitials and vacancies have been estimated and compared to their respective migration energies.

Shahi, K.↗

NASA NTRS1991

A coated-wire ion-selective electrode for ionic calcium measurements

A coated-wire ion-selective electrode for measuring ionic calcium was developed, in collaboration with Teknektron Sensor Development Corporation (TSDC). This coated wire electrode sensor makes use of advanced, ion-responsive polyvinyl chloride (PVC) membrane technology, whereby the electroactive agent is incorporated into a polymeric film. The technology greatly simplifies conventional ion-selective electrode measurement technology, and is envisioned to be used for real-time measurement of physiological and environment ionic constituents, initially calcium. A primary target biomedical application is the real-time measurement of urinary and blood calcium changes during extended exposure to microgravity, during prolonged hospital or fracture immobilization, and for osteoporosis research. Potential advanced life support applications include monitoring of calcium and other ions, heavy metals, and related parameters in closed-loop water processing and management systems. This technology provides a much simplified ionic calcium measurement capability, suitable for both automated in-vitro, in-vivo, and in-situ measurement applications, which should be of great interest to the medical, scientific, chemical, and space life sciences communities.

Hines, John W.↗

NASA NTRS2003

Intercomparisons of Airborne Measurements of Aerosol Ionic Chemical Composition during TRACE-P and ACE-Asia

As part of the two field studies, Transport and Chemical Evolution over the Pacific (TRACE-P), and the Asian Aerosol Characterization Experiment (ACEAsia), the inorganic chemical composition of tropospheric aerosols was measured over the western Pacific from three separate aircraft using various methods. Comparisons are made between the rapid online techniques of the Particle Into Liquid Sampler (PILS) for measurement of a suite of fine particle ionic compounds and a mist chamber (MC/IC) measurement of fine sulfate, and the longer time-integrated filter and multi-orifice impactor (MOI) measurements. Comparisons between identical PILS on two separate aircraft flying in formation showed that they were highly correlated (e.g., sulfate r(sup 2) of 0.95), but were systematically different by 10 +/- 5% (linear regression slope and 95% confidence bounds), and had generally higher concentrations on the aircraft with a low turbulence inlet and shorter inlet-to-instrument transmission tubing. Comparisons of PILS and mist chamber measurements of fine sulfate on two different aircraft during formation flying had an 3 of 0.78 and a relative difference of 39% +/- 5%. MOI ionic data integrated to the PILS upper measurement size of 1.3 pm sampling from separate inlets on the same aircraft showed that for sulfate, PILS and MOI were within 14% +/- 6% and correlated with an r(sup 2) of 0.87. Most ionic compounds were within f 30%, which is in the range of differences reported between PILS and integrated samplers from ground-based comparisons. In many cases, direct intercomparison between the various instruments is difficult due to differences in upper-size detection limits. However, for this study, the results suggest that the fine particle mass composition measured from aircraft agree to within 30-40%.

Ma, Y.↗

NASA NTRS2004

Ionic Liquids and New Proton Exchange Membranes for Fuel Cells

There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research Center during this summer is to develop and characterize proton exchange membranes doped with ionic liquids. The main techniques used to characterize these materials are: Impedance Spectroscopy, NMR, DSC, TGA, DMA, IR, and SEM ...

Belieres, Jean-Philippe↗

NASA NTRS2007

Use of Ionic Liquids in Rod-Coil Block Copolyimides for Improved Lithium Ion Conduction

Solvent-free, solid polymer electrolytes (SPE) have the potential to improve safety, increase design flexibility and enhance performance of rechargeable lithium batteries. Solution based electrolytes are flammable and typically incompatible with lithium metal anodes, limiting energy density. We have previously demonstrated use of polyimide rod coil block copolymers doped with lithium salts as electrolytes for lithium polymer batteries. The polyimide rod blocks provide dimensional stability while the polyethylene oxide (PEO) coil portions conduct ions. Phase separation of the rods and coils in these highly branched polymers provide channels with an order of magnitude improvement in lithium conduction over polyethylene oxide itself at room temperature. In addition, the polymers have been demonstrated in coin cells to be compatible with lithium metal. For practical use at room temperature and below, however, at least an order of magnitude improvement in ion conduction is still required. The addition of nonvolatile, room temperature ionic liquids has been shown to improve the ionic conductivity of high molecular weight PEO. Herein we describe use of these molten salts to improve ionic conductivity in the rod-coil block copolymers.

Meador, Mary Ann B.↗

NASA NTRS2011

Ionic Liquids to Replace Hydrazine

A method for developing safe, easy-to-handle propellants has been developed based upon ionic liquids (ILs) or their eutectic mixtures. An IL is a binary combination of a typically organic cation and anion, which generally produces an ionic salt with a melting point below 100 deg C. Many ILs have melting points near, or even below, room temperature (room temperature ionic liquids, RTILs). More importantly, a number of ILs have a positive enthalpy of formation. This means the thermal energy released during decomposition reactions makes energetic ILs ideal for use as propellants. In this specific work, to date, a baseline set of energetic ILs has been identified, synthesized, and characterized. Many of the ILs in this set have excellent performance potential in their own right. In all, ten ILs were characterized for their enthalpy of formation, density, melting point, glass transition point (if applicable), and decomposition temperature. Enthalpy of formation was measured using a microcalorimeter designed specifically to test milligram amounts of energetic materials. Of the ten ILs characterized, five offer higher Isp performance than hydrazine, ranging between 10 and 113 seconds higher than the state-of-the-art propellant. To achieve this level of performance, the energetic cations 4- amino-l,2,4-triazolium and 3-amino-1,2,4-triazolium were paired with various anions in the nitrate, dicyanamide, chloride, and 3-nitro-l,2,4-triazole families. Protonation, alkylation, and butylation synthesis routes were used for creation of the different salts.

Koelfgen, Syri↗

NASA NTRS2014

Investigation of Structure and Transport in Li-Doped Ionic Liquid Electrolytes: [pyr14][TFSI], [pyr13][FSI] and [EMIM][BF4]

Ionic liquid electrolytes have been proposed as a means of improving the safety and cycling behavior of advanced lithium batteries; however, the properties of these electrolytes under high lithium doping are poorly understood. Here, we employ both polarizable molecular dynamics simulation and experiment to investigate the structure, thermodynamics and transport of three potential electrolytes, N-methyl-Nbutylpyrrolidinium bis(trifluoromethylsufonyl)imide ([pyr14][TFSI]), N- methyl-Npropylpyrrolidinium bis(fluorosufonyl)imide ([pyr13][FSI]), and 1-ethyl-3-- methylimidazolium boron tetrafluoride ([EMIM][BF4]), as a function of Li-salt concentration and temperature. Structurally, Li(+) is shown to be solvated by three anion neighbors in [pyr14][TFSI] and four anion neighbors in both [pyr13][FSI] and [EMIM][BF4], and at all levels of x(sub Li) we find the presence of lithium aggregates. Furthermore, the computed density, diffusion, viscosity, and ionic conductivity show excellent agreement with experimental data. While the diffusion and viscosity exhibit a systematic decrease and increase, respectively, with increasing x(sub Li), the contribution of Li(+) to ionic conductivity increases until reaching a saturation doping level of x(sub Li) is approximately 0.10. Comparatively, the Li(+) conductivity of [pyr14][TFSI] is an order of magnitude lower than that of the other liquids, which range between 0.1 - 0.3 mS/cm. The differences in Li(+) transport are reflected in the residence times of Li(+) with the anions, which are revealed to be much larger for [pyr14][TFSI] (up to 100 ns at the highest doping levels) than in either [EMIM][BF4] or [pyr13][FSI]. Finally, we comment on the relative kinetics of Li(+) transport in each liquid and we present strong evidence for transport through anion exchange (hopping) as opposed to the net motion of Li(+) with its solvation shell (vehicular).

lithium batteries↗

NASA NTRSDate not supplied

Investigation of Ionic Liquids Isolated Iron for Ductile Iron Castings

As research continues for missions beyond low-Earth orbit, in-situ resource utilization (ISRU) methods are critical. To colonize the Lunar or Martian surface, the ability to manufacture mechanical and structural components with local resources is essential. Ionic liquids are being studied at NASA Marshall Space Flight Center (MSFC) to harvest elemental metals from meteorites and oxides in regolith. In this investigation, the viability of casting ductile iron using ionic liquids sourced iron and nickel was explored given ductile iron’s range of applications and performance as an as-cast alloy. Small ingots were produced using commercial silicon, manganese, and magnesium with carbon sourced from the by-products of a life support system currently being tested at MSFC. Samples were cast and compared to commercial ductile iron with phase transformation diagrams, microstructures, and hardness. Results showed ionic liquids sourced elements are a viable source of elemental alloying materials for a range of ductile iron alloys.

Blake Stewart↗

NASA NTRSDate not supplied

Early Results from a Broad Compatibility Study of Various Materials with Ionic Silver Biocide

Ionic silver is baselined for microbial control in spacecraft potable water systems forfuture exploration missions, but materials compatibility analysis is required to evaluate thepassive depletion of ionic silver concentration onto wetted material surfaces over time.Various articles concerning such testing have been published that examine interactions withwater containing ionic silver biocide, but most tests have focused on only a couple ofmaterials each and comparing results of different evaluations to one another has provedchallenging.This paper reports the first results from static exposure testing of a large arrayof material coupons to a 400 parts per billion (ppb) aqueous silver fluoride (AgF) solution,using a surface to volume ratio of approximately 2 cm-1. The test is designed in two mainstages. Stage 1 is a one-week screening to evaluate silver uptake. Materials that performmodestly to well after that week are promoted to Stage 2, which is a longer test with periodicsampling to examine the silver uptake rates over time; these samples are evaluated for otherwater quality parameters in addition to the remaining silver concentration. In a tangentialinvestigation, select materials that take up some silver in Stage 1 may be “aged” by repeatingthe Stage 1 test to determine whether repeated exposure reduces silver uptake rate, andsuccessfully aged materials may then continue to Stage 2 testing. The materials under testinclude metallic and polymeric materials with various surface finishes, treatments, andcoatings, as well as select other materials historically used in spacecraft water systems. Thistest began in August 2019, and thus only includes early results; future follow-on papers willinclude additional results as the test progresses. The ultimate goal builds a broad, easilycomparable data set that can be used to guide material selections for silver biocide-compatible spacecraft water system design.

Silver Biocide↗

NASA NTRS2024

Substrate Matters: Ionic Silver Alters Lettuce Growth, Nutrient Uptake, and Root Microbiome in a Hydroponics System

Ionic silver (Ag+) is being investigated as a residual biocide for use in NASA spacecraft potable water systems on future crewed missions. This water will be used to irrigate future spaceflight crop production systems. We have evaluated the impact of three concentrations (31 ppb, 125 ppb, and 500 ppb) of ionic silver biocide solutions on lettuce in an arcillite (calcinated clay particle substrate) and hydroponic (substrate-less) growth setup after 28 days. Lettuce plant growth was reduced in the hydroponic samples treated with 31 ppb silver and severely stunted for samples treated at 125 ppb and 500 ppb silver. No growth defects were observed in arcillite-grown lettuce. Silver was detectable in the hydroponic-grown lettuce leaves at each concentration but was not detected in the arcillite-grown lettuce leaves. Specifically, when 125 ppb silver water was applied to a hydroponics tray, Ag+ was detected at an average amount of 7 μg/g (dry weight) in lettuce leaves. The increase in Ag+ corresponded with a decrease in several essential elements in the lettuce tissue (Ca, K, P, S). In the arcillite growth setup, silver did not impact the plant root zone microbiome in terms of alpha diversity and relative abundance between treatments and control. However, with increasing silver concentration, the alpha diversity increased in lettuce root samples and in the water from the hydroponics tray samples. The genera in the hydroponic root and water samples were similar across the silver concentrations but displayed different relative abundances. This suggests that ionic silver was acting as a selective pressure for the microbes that colonize the hydroponic water. The surviving microbes likely utilized exudates from the stunted plant roots as a carbon source. Analysis of the root-associated microbiomes in response to silver showed enrichment of metagenomic pathways associated with alternate carbon source utilization, fatty-acid synthesis, and the ppGpp (guanosine 3′-diphosphate 5′-diphosphate) stringent response global regulatory system that operates under conditions of environmental stress. Nutrient solutions containing Ag+ in concentrations greater than 31 ppb in hydroponic systems lacking cation-exchange capacity can severely impact crop production due to stunting of plant growth.

lettuce↗

DOE OSTI2020

Methods for liquid extraction of rare earth metals using ionic liquids

A method for extracting a rare earth element from a rare earth-containing substance, the method comprising mixing the rare earth-containing substance with a protic ionic liquid, such as: wherein R1 is selected from hydrogen atom and hydrocarbon groups containing 1 to 6 carbon atoms; R2 and R3 are independently selected from hydrocarbon groups containing 1 to 12 carbon atoms; and X− is an anionic species; to produce a composition of the formula (RE)(amide)yXz at least partially dissolved in the protic ionic liquid, wherein RE is at least one rare earth element having an atomic number selected from 39, 57-71, and 90-103; y is 2-6; z is a number that charge balances the total positive charge of RE; and the amide is the conjugate base of the cationic portion of the protic ionic liquid of Formula (1) and has the following formula:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

High gravity, fed-batch ionic liquid based process for deconstructing biomass

In one aspect, the present invention provides methods for preparing a fermentation product. The methods include pre-treating a mixture of biomass and ionic liquid, wherein the ionic liquid comprises a choline cation and the biomass comprises polysaccharide and lignin. The methods further include forming hydrolysates from the introduction of glycoside hydrolase to the pre-treated mixture at conditions sufficient to produce a sugar composition mixture for fermentation steps. The present invention provides methods for loading biomass mixtures in a batch-fed process, wherein the biomass slurries can be loaded into water or a concentrated sugar composition for hydrolysate production. The methods can be performed in a one-pot process, wherein the ionic liquids are present in the mixtures throughout each step. Aspects of the invention provide compositions of sugar composition mixtures and fermentation product mixtures.

Xu, Feng↗

DOE OSTI2021

Enhanced colorimetric apparatus and method for explosives detection using ionic liquids

An inspection tester for testing a surface for suspected explosive substances includes a body unit, a breakable ampoule carried by the body unit, and an ionic explosive detecting reagent in the breakable ampoule wherein the body unit and the breakable ampoule are positioned to deliver the ionic explosive detecting reagent to the surface for testing the surface for the suspected explosive substances. The ionic explosive detecting reagent is a salt in a liquid state.

Reynolds, John G.↗

DOE OSTI2022

Thermally sensitive ionic redox transistor

A thermally sensitive ionic redox transistor comprises a solid channel, a solid reservoir layer, and a solid electrolyte layer disposed between the channel and the reservoir layer. A conductance of the channel is varied by changing the concentration of ions such as oxygen vacancies in the channel layer. Ionic conductivity of the gate, electrolyte, and channel layers increase with increasing temperature. Ion or vacancy transport between the channel and the reservoir layer across the electrolyte layer occurs in response to applying a voltage between the channel and the reservoir layer when the device is heated to an elevated temperature. When the device is cooled below the elevated temperature, the ions are trapped in one or more of the layers because the materials lose their ionic conductivity. A state of the redox transistor can be read by measuring the conductance of the channel.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2022

System for an ionic liquid-based electrolyte for high energy battery

A system for electrical energy production from chemical reagents in a compartmentalized cell includes: at least two electrodes, comprising at least one anode and at least one cathode; at least one separator, that separates the anodes and the cathodes; and an ionic liquid electrolyte system. The system can be a battery or one or more cells of a battery system. The ionic liquid electrolyte system comprises an ionic liquid solvent; an ether co-solvent, comprising a minority fraction, by weight, of the electrolyte; and a lithium salt. In preferred variations, the anode is a lithium metal anode and the cathode is a metal oxide cathode and the separator is a polyolefin separator.

Wang, Richard Y.↗

DOE OSTI2023

System for an ionic liquid-based electrolyte for high energy battery

Wang, Richard Y.↗