Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Ionic liquid”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Impact of fluorination on Li + solvation and dynamics in ionic liquid-hydrofluoroether locally concentrated electrolytes

The thermal, physical, structural, and transport properties of ionic liquid (IL) electrolytes based on n-methyl-n-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide [PYR14][TFSI] and Li-salts of lithium (nonafluorobutane)(trifluoromethanesulfonyl)imide [Li][IM14] and [Li][TFSI] (0 ≤ x Li ≤ 0.3), with addition of 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) (0 ≤ x TTE ≤ 0.45) were studied. While [IM14] increases glass transition, TTE improves conductivity over a wider liquidus range. Li + is solvated primarily by [TFSI] with some contribution by [IM14]. However, both 7 Li- 19 F HOESY NMR and spatial distribution functions (SDFs) derived from molecular dynamics (MD) indicate short contacts between the fluorines of TTE and Li + . This is a result of tighter anion-solvated Li + without aggregation of the Li + solvates, consistent with Raman measurements, thus confirming the existence of fluorous domains in the bulk which leads to improved fluidity and a Li + diffusivity of 1.26 x 10 –12 m 2 /s at 0 °C (x Li = 0.20) with a Li + transference of 0.16. Improved transport properties translated to a higher capacity of the TTE/IL electrolyte in a Li||LiFePO 4 half-cell with 95mAh/g at 0.1C, compared to the IL electrolyte without TTE (60 mAh/g). Furthermore, this study demonstrates the tunability of solvation and transport properties in IL electrolytes by asymmetric fluorinated anions and hydrofluoroether co-solvents for low temperature Li-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2020

Colloidal Three-Dimensional Covalent Organic Frameworks and Their Application as Porous Liquids

Developing solid porous materials into free-flowing liquids with permanent porosity is a promising strategy for overcoming certain limitations of conventional sorbent materials employed in gas storage and separation applications. The ability to control the pore size and chemical functionalities of organic frameworks gives these particular nanoporous materials distinct advantages over other small cage-like molecules or hollow particles that have been developed into porous liquids. Here, we describe the synthesis of a 3D imine-linked colloidal covalent organic framework (COF)-based porous liquid, designed for efficient size-exclusion of solvent, as well as for long-term stability. By tethering ionic liquids to the colloid surface, the colloids can be dried, purified, and resuspended in a variety of solvents without irreversible aggregation typically observed of COF colloids. Colloid size could be controlled between 50 and 400 nm, with surface areas as high as 800 m2/g. The 3D intertwining morphology of the colloids had pore sizes ranging from 5 to 14 Å, allowing them to efficiently sizeexclude bulky ionic liquids. The COF colloids were stable towards flocculation in an ionic liquid for > 1 year. Permanent porosity was confirmed with a combination of 19F NMR measurements and gas sorption techniques. CO2 and CH4 uptake in these porous liquids increased more than 10 and 20-fold, respectively, over non-porous, neat ionic liquid control samples. The work not only advances the state of COF-based colloid science but also represents a practical advance towards developing more robust, tunable framework-based porous liquid materials for a host of gas storage and separation applications.

Mow, Rachel E.↗
DOE OSTI2022

Investigation of the role of hydrogen bonding in ionic liquid-like salts with both N- and S-soft donors

In search of ionic liquids (ILs) with multiple types of soft donor atoms capable of preferentially complexing a range of soft metal ions over harder ions, we investigated structural clues to the role of hydrogen bonding in IL behavior through a series of salts with anions containing both N- and S-donor atoms based on azole thiolates. Reaction of equimolar amounts of triethylamine (Et 3 N) or diisobutylamine (DBA) with 1-phenyl-1H-tetrazole-5-thiol (PhTzSH), 1-methyl-1H-tetrazole-5-thiol (MeTzSH), or 5-methyl-1,3,4-dithiazole-2-thiol (MeDiTSH) yielded [Et 3 NH][MeTzS] (1), a yellow liquid, and the low melting yellow solids [DBAH][MeTzS] (2), [Et 3 NH][PhTzS] (3), [DBAH][PhTzS] (4), [Et 3 NH][MeDiTS] (5), and [DBAH][MeDiTS] (6). Thermal analysis revealed that all of them qualify as ILs with melting points below 100 °C. Single crystal X-ray structure analysis of 2–6 revealed the presence of an extensive H-bonding network that includes the rare N–H$\cdots$S hydrogen bonds in 3, 4, and 6. These weaker interactions appear to significantly influence thermal behavior, where strong bonding leads to higher melting temperatures and lower decomposition points.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Unveiling the porosity effect of superbase ionic liquid-modified carbon sorbents in CO 2 capture from air

Direct air capture (DAC) of CO 2 represents one of the most promising technologies to achieve negative carbon emissions. In this work, the superbase ionic liquids (ILs)-modified carbon substrates were developed for DAC of CO 2 by harnessing the strong CO 2 binding capability of IL and the ordered porous channels of the carbon supports. Detailed porosity analysis revealed that the IL with an aromatic cation and an oxygenate anion preferred to fill the micropores, and a thin layer was created on the surface of the mesopores. Strong π-π interaction between the IL layer and the carbon surface was disclosed by wide-angle X-ray scattering (WAXS) analysis, leading to enhanced thermal stability of the IL phase. For the same lL coating amount, the DAC of CO 2 evaluation revealed that a larger mesopore size and pore volume in the carbon/IL composite materials led to higher CO 2 uptake capacity by exposing more active sites to integrate CO 2 from diluted sources. Further, the thermodynamic analysis confirmed the critical role of IL coating in providing strong chemisorption sites and significantly improved selectivity to enrich the diluted CO 2 from the air atmosphere. This work provides guidance on leveraging the scaffolds' surface properties and porosities of the scaffolds to optimize DAC of CO 2 behavior.

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

A Comparative Study of Imidazolium-Based Ionic Liquid-Single-Walled Carbon Nanotube Composites with Enhanced Conductivity Properties for Supercapacitor Applications

Mixtures of ionic liquids (ILs) containing single-walled carbon nanotubes (SWCNTs) were prepared and characterized to obtain electrolytes with optimized transport properties for use in energy storage devices such as supercapacitors. Imidazolium ILs bearing cations with side chains of different functionality coupled with bis(trifluoromethylsulfonyl)amide (NTf 2- ) or bis(fluorosulfonyl)-amide (FSA-) anions, were used in mixtures containing up to 5 wt% SWCNTs. At and above 2 wt% nanotube loading, the mixtures exhibited higher conductivities than the pure ILs, in spite of the extremely high viscosities. Loadings of 5 wt% produced very high conductivities, and studies of the temperature dependence indicated a change in the charge transport mechanism between 2 and 5 wt% loading. At 5 wt% loading, the highest conductivities (up to 540 mS/cm at 25 °C) were obtained for the ILs containing the NTf 2- anion. Overall, these results can significantly contribute to the development of improved energy storage devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2014

Branched Rod-Coil Polyimide-Poly(Alkylene Oxide) Copolymers and Electrolyte Compositions

Crosslinked polyimide-poly(alkylene oxide) copolymers capable of holding large volumes of liquid while maintaining good dimensional stability. Copolymers are derived at ambient temperatures from amine endcapped amic-acid oligomers subsequently imidized in solution at increased temperatures, followed by reaction with trifunctional compounds in the presence of various additives. Films of these copolymers hold over four times their weight at room temperature of liquids such as ionic liquids (RTIL) and/or carbonate solvents. These rod-coil polyimide copolymers are used to prepare polymeric electrolytes by adding to the copolymers various amounts of compounds such as ionic liquids (RTIL), lithium trifluoromethane-sulfonimide (LiTFSi) or other lithium salts, and alumina.

Meador, Maryann B.↗
DOE OSTI2023

Species-Selective Detection of Volatile Organic Compounds by Ionic Liquid-Based Electrolyte Using Electrochemical Methods

The detection of volatile organic compounds (VOCs) is an important topic for environmental safety and public health. However, the current commercial VOC detectors suffer from cross-sensitivity and low reproducibility. In this work, we present species-selective detection for VOCs using an electrochemical cell based on ionic liquid (IL) electrolytes with features of high selectivity and reliability. The voltammograms measured with the IL-based electrolyte absorbing different VOCs exhibited species-selective features that were extracted and classified by linear discriminant analysis (LDA). The detection system could identify as many as four types of VOCs, including methanol, ethanol, acetone, formaldehyde, and additional water. A mixture of methanol and formaldehyde was detected as well. The sample required for the VOCs classification system was 50 μL, or 1.164 mmol, on average. The response time for each VOC measurement is as fast as 24 s. The volume of VOCs such as formaldehyde in solution could also be quantified by LDA and electrochemical impedance spectroscopy techniques, respectively. The system showed a tunable detection range for 1.6 and 16% (w/v) CH 2 O solution by adjusting the composition of the electrolyte. The limit of detection was as low as 1 μL. For the 1.6% CH 2 O solution, the linearity calibration range was determined to be from 5.30 to 53.00 μmol with a limit of detection at 0.53 μmol. The mechanisms for VOCs determination and quantification are also thoroughly discussed. Finally, it is expected that this work could provide a new insight into the concept of electrochemical detection of VOCs with machine learning analysis and be applied to both VOCs gas monitoring and fluid detection.

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

Marine Toxicity, Biodegradability, and Rolling-Sliding Tribological Performance of Ionic Liquid-Enhanced Environmentally-Acceptable Lubricants for Tidal Turbomachinery

Environmentally acceptable lubricants (EALs) are increasingly being recognized in many fields including waterpower, hydraulics, water transport, agricultural machinery, offshore wind turbines, etc. Specifically, high-performance EALs are demanded for tidal turbomachinery to ensure high efficiency and reliability and avoid the significant risk of direct contamination of the marine ecosystem upon leaks. Here we report a new development of ionic liquid (IL)-enhanced EALs for tidal energy. One short-chain phosphonium phosphate and one short-chain ammonium phosphate ILs were used as the candidate additives and the IL-containing EALs demonstrated significantly improved lubricating performance, much lower toxicity, and increased biodegradability compared with commercial baselines. Specifically, in a rolling-sliding test simulating the operation of a model tidal turbine gearbox bearing, an EAL containing the ILs at a 0.5 wt % concentration demonstrated 40% lower friction, 45% less wear loss, substantially reduced rolling contact fatigue-induced surface damage, and one order of magnitude lower vibration noise compared with a commercial gear oil. In an EPA standard toxicity test, 90 and 70% survival of marine biota was observed when exposed to an EAL containing 5 wt % of the short-chain phosphonium phosphate and ammonium phosphate ILs, respectively, while the selected commercial gear oil and bioderived additive killed all marine biota. In a standard biodegradability test, 2 wt % addition of the phosphonium phosphate IL not only retained the EAL’s ready biodegradability but further boosted the oil decomposition from a range of 60–80% to a higher level of 80–95%. Conversely, adding the commercial bioderived additive downgraded the EAL from readily to inherently biodegradable. Furthermore, this work offers scientific insights for development of ILs as potential EAL additives for marine energy and broader applications.

additives↗
DOE OSTI2024

PILBCP-IL Composite Ionomers for High Current Density Performance

Wide-spread commercialization of fuel cell electric vehicles using proton exchange membrane fuel cell (PEMFC) power sources requires that several existing limitations be addressed. These include: (1) a reduction in platinum (Pt) loading in the catalytic electrodes, (2) improvements in reactant and electronic mobility throughout the catalytic electrodes, (3) reduction in the reliance on materials derived from polluting “forever chemicals”, and (4) a significant improvement in the operational longevity of catalytic electrode components. In this project, a team of two universities, Drexel University and Texas A&M University, one national lab, National Renewable Energy Laboratory, and one company, General Motors, collaborated to develop a new cathode ionomer chemistry that would address these limitations and result in an improvement in performance over existing ionomer materials. The key technology developed through this collaborative project was a composite cathode ionomer encompassing an ionic liquid interlayer between Pt catalysts and a sulfonated polymerized ionic liquid block co-polymer (S-PILBCP) that possess the orthogonal properties of protonic conductivity and ionic liquid enhanced kinetics and durability (see schematic in Figure 1). The composite S-PILBCP ionomer eliminates many of the existing issues with perfluorosulfonic acid-based ionomers including active site blocking by sulfonate specific adsorption, restricted O 2 transport through ionomer films, limited humidity tolerance and active area loss for carbon pore confined catalyst particles, and use of polluting “forever chemicals”. Following successful integration of the developed composite ionic liquid into a PEMFC cathode catalyst layer, we demonstrate enhanced performance over Nafion containing cathodes with Pt/C and PtCo/C at both low and high current density. The performance with our composite S-PILBCP ionomer meets the Department of Energy (DOE) targets for light duty vehicle applications

08 HYDROGEN↗
DOE OSTI2026

Structure and Dynamics of Imidazolium in an Ionic Liquid-PEGDA Iongel via IR, 2D-IR, and NMR Spectroscopy

Fourier transform infrared (FTIR) absorption spectroscopy, ultrafast two-dimensional infrared (2D-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and density functional theory (DFT) calculations show that, in iongels composed of 1-ethyl-3-methylimidazolium bis(trifluoromethyl\-sulfonyl)imide ([C 2 C 1 Im][Tf 2 N]}) and cross-linked poly(ethylene glycol)diacrylate (cl-PEGDA), imidazolium cations solvate PEGDA chains in tight and loose complexes. H/D isotope substitution at the 2-position of the imidazolium ring simplifies the CH-stretching vibrational bands. Tight complexes are characterized by stronger, directional hydrogen bonding interactions between the 2-position of the imidazolium ring and the ethereal oxygens. The loose complexes resemble bulk ionic liquid (IL) non-specifically perturbed by the PEGDA chains.

ionic liquids, carbon dioxide, cross-linked PEGDA,↗
DOE OSTI2021

High-Efficiency Conversion of Ionic Liquid-Pretreated Woody Biomass to Ethanol at the Pilot Scale

We report that with a diverse and widely distributed global resource base, woody biomass is a compelling organic feedstock for conversion to renewable liquid fuels. In California, woody biomass comprises the largest fraction of underutilized biomass available for biofuel production, but conversion to fuels is challenged both by recalcitrance to deconstruction and by toxicity toward downstream saccharification and fermentation due to organic acids and phenolic compounds generated during pretreatment. In this study, we optimize pretreatment and scale-up of an integrated one-pot process for deconstruction of California woody biomass using the ionic liquid (IL) cholinium lysinate [Ch][Lys] as a pretreatment solvent. By evaluating the impact of solid loading, solid removal, yeast acclimatization, fermentation temperature, fermentation pH, and nutrient supplementation on final ethanol yields and titers, we achieve nearly full conversion of both glucose and xylose to ethanol with commercial C5-utilizing Saccharomyces cerevisiae. We then demonstrate process scalability in 680 L pilot-scale fermentation, achieving >80% deconstruction efficiency, >90% fermentation efficiency, 27.7 g/L ethanol titer, and >80% ethanol distillation efficiency from the IL-containing hydrolysate post fermentation. This fully integrated process requires no intermediate separations and no intermediate detoxification of the hydrolysate. Using an integrated biorefinery model, current performance results in a minimum ethanol selling price of $\$$8.8/gge. Reducing enzyme loading along with other minor process improvements can reduce the ethanol selling price to $\$$3/gge. This study is the largest scale demonstration of IL pretreatment and biofuel conversion known to date, and the overall biomass-to-ethanol efficiencies are the highest reported to date for any IL-based biomass-to-biofuel conversion.

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

Draft Genome Assemblies of Ionic Liquid-Resistant Yarrowia lipolytica PO1f and Its Superior Evolved Strain, YlCW001

Adaptive laboratory evolution of Yarrowia lipolytica PO1f in the benchmark ionic liquid (IL; 1-ethyl-3-methylimidazolium acetate) produced a superior IL-tolerant microorganism, strain YlCW001. In this work, we report the genome sequences of PO1f and YlCW001 to explore the robustness of Y. lipolytica and its potential use as a microbial platform for producing fuels and chemicals.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Solvent Processing and Ionic Liquid-Enabled Long-Range Vertical Ordering in Block Copolymer Films with Enhanced Film Stability

Rapid and reliable processing methods for forming ordered block copolymer (BCP) materials with low defect density in a thin film geometry are required for many nanotechnology applications. Vertically aligned BCP structures, in particular, have applications ranging from nanolithography for electronics and photonics to nanoporous membranes for water remediation and novel batteries for flexible electronics. However, the attainment of nearly complete vertical orientational order of the BCP ordered phase remains challenging. Solvent-based techniques, such as direct immersion annealing (DIA) and solvent vapor annealing (SVA), have immense potential for these applications of BCP films, as it allows for tuning of their thermodynamic, structural, and chain mobility driven kinetic properties. We first demonstrate that DIA, using a judicious choice of binary solvent mixtures along with a relatively hydrophobic ionic liquid (IL), induces the rapid vertical ordering in polystyrene-b-polymethylmethacrylate (PS-PMMA) block copolymer in lamellar films. The IL establishes synergy to the binary solvent mixture of toluene and heptane to 1 create a near-neutral solvent environment for attaining the vertical microstructure of the BCP. Next, we show that IL can suppress the de-wetting of the PS-PMMA films to achieve long-range order using SVA in cylindrical films for long annealing times. Both vertical and horizontal morphology is attained in these films by selecting different solvent environments. Furthermore, attaining enhanced vertical and horizontal BCP structure with long-range defect-free order by tuning solvent quality and using additives like IL can render them useful for many nanotech applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Ionic Liquid-Mediated Scanning Probe Electro-Oxidative Lithography as a Novel Tool for Engineering Functional Oxide Micro- and Nano-Architectures

Functional oxides have extensively been investigated as a promising class of materials in a broad range of innovative applications. Harnessing the novel properties of functional oxides in micro- to nano-scale applications hinges on establishing advanced fabrication and manufacturing techniques able to synthesize these materials in an accurate and reliable manner. Oxidative scanning probe lithography (o-SPL), an atomic force microscopy (AFM) technique based on anodic oxidation at the water meniscus formed at the tip/substrate contact, not only combines the advantages of both “top-down” and “bottom-up” fabrication approaches, but also offers the possibility of fabricating oxide nanomaterials with high patterning accuracy. While the use of self-assembled monolayers (SAMs) broadened the application of o-SPL, significant challenges have emerged owing to the relatively limited number of SAM/solid surface combinations that can be employed for o-SPL, which constrains the ability to control the chemistry and structure of oxides formed by o-SPL. Here, in this work, a new o-SPL technique that utilizes room-temperature ionic liquids (RTILs) as the functionalizing material to mediate the electrochemistry at AFM tip/substrate contacts is reported. The results show that the new IL-mediated o-SPL (IL-o-SPL) approach allows sub-100 nm oxide features to be patterned on a model solid surface, namely steel, with an initiation voltage as low as -2 V. Moreover, this approach enables high tunability of both the chemical state and morphology of the patterned iron oxide structures. Owing to the high chemical compatibility of ILs, which derives from the possibility of synthesizing ILs able to adsorb on a wide variety of solid surfaces, IL-o-SPL can be extended to other material surfaces and provide the opportunity to accurately tailor the chemistry, morphology, and electronic properties within nanoscale domains, thus opening new pathways to the development of novel micro- and nano-architectures for advanced integrated devices.

36 MATERIALS SCIENCE↗
NASA NTRS2015

Evaluation of Two Ionic Liquid-Based Epoxies from the MISSE-8 (Materials International Space Station Experiment-8) Sample Carrier

Two sets of epoxy mixtures, both containing the same ionic liquid (IL) based resin but utilizing two different curing agents, were evaluated after spending more than two years of continual space exposure outside of the International Space Station on the MISSE-8 sample rack. During this period the samples, positioned on nadir side, also experienced some 12,500 thermal cycles between approximately -40C and +40 C. Initial examination showed some color change, a miniscule weight variance, and no cracks or de-bonding from the sample substrate. Microscopic examination of the surface reveled some slight deformities and pitting. These observations, and others, are discussed in view of the ground-based control samples. Finally, the impetus of this study in terms of space applications is presented.

Rabenberg, Ellen↗
DOE OSTI2025

Solvated Ionic Liquid-based Electrolytes: Experimental Characterization, Atomistic Modeling and Applications in Energy Storage

This study aimed on understanding the molecular structure and transport mechanisms of high-concentration lithium electrolytes, with a particular focus on solvate ionic liquids (SILs) based on glyme solvents, for use in next-generation, high-voltage energy storage systems. The hypothesis is that the composition of the solvents in these electrolytes can be designed and adjusted to control cation solvation, enabling charge transport via an ion-hopping mechanism. This mechanism resembles Grotthuss conduction of protons in water and is independent of electrolyte viscosity. The experimental studies employed linear and nonlinear infrared spectroscopy (FTIR and 2D IR), electrochemical measurements, and vibrational probes.

25 ENERGY STORAGE↗
NASA NTRS2013

High-Performance, Low-Temperature-Operating, Long-Lifetime Aerospace Lubricants

The synthesis and characterization of six new ionic liquids, with fluoroether moeties on the imidazolium ring, each with vapor pressures shown to be <10(exp -7 Torr at 25 C, have been demonstrated. Thermal stability of the ionic liquids up to 250 C was demonstrated. The ionic liquids had no measurable influence upon viscosity upon addition to perfluoropolyether (PFPE) base fluids. They also had no measureable influence upon corrosion on steel substrates upon addition to base fluids. In general, 13 to 34% lower COFs (coefficients of friction), and 30 to 80% higher OK load of base fluids upon addition of the ionic liquids was shown. The compound consists of a 1,3-disubstituted imidazolium cation. The substituents comprise perfluoroether groups. A bis(trifluoromethanesulfonyl) imide anion counterbalances the charge. The fluorinated groups are intended to enhance dispersion of the ionic liquid in the PFPE base fluid. The presence of weak Van der Waals forces associated with fluorine atoms will limit interaction of the substituents on adjacent ions. The longer interionic distances will reduce the heat of melting and viscosity, and will increase dispersion capabilities.

Bergeron, Bryan↗