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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Anion chemical composition of poly(ethylene oxide)-based sulfonylimide and sulfonate lithium ionomers controls ion aggregation and conduction

Maximizing ion conduction in single-ion-conducting ionomers is essential for their application in energy-related technologies such as Li-ion batteries. Understanding the anion chemical composition impacts on ion conduction offers new perspectives to maximize ion transport, since the current approach of lowering T g has apparently reached a limit (lowest T g ~ 190 K, highest conductivity ~10 -5 –10 -4 S cm -1 ). Here, a series of random ionomers are synthesized by copolymerizing poly(ethylene glycol)methacrylate with either sulfonylimide lithium methacrylate (MTLi) or sulfonate lithium methacrylate (MSLi) using reversible addition–fragmentation chain transfer (RAFT) polymerization. Li-Ion conduction and self-diffusion coefficients (DLi+) of the ionomers are characterized with dielectric relaxation spectroscopy (DRS) and pulsed-field-gradient (PFG) NMR diffusometry, respectively. Increasing ion content decreases the Li-ion conductivity and D Li+ , as expected from the increased T g . Moreover, a considerably lower ionic conductivity and D Li+ are observed for MSLi compared to MTLi at constant ion content and T g /T. As revealed from X-ray scattering, strong ion aggregation in MSLi results in much lower conductivity and DLi+ compared with less aggregated MTLi based on the more delocalized sulfonylimide anion. These results emphasize the detrimental and molecularly specific role of ion aggregation in Li-ion conductivity, and highlight the necessity for minimizing ion aggregation via the rational choice of anion chemical composition.

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

Constructing a square-like copper cluster to boost C–C coupling for CO 2 electroreduction to ethylene

The CO 2 electroreduction reaction (CO 2 ER) to ethylene (C 2 H 4 ) offers the dual promise of lowering CO 2 emission while storing energy from renewable electricity, for which the development of highly efficient electrocatalysts is of great significance. Herein, by means of density functional theory (DFT) computations, we designed an electrocatalyst for CO 2 -to-C 2 H 4 conversion by anchoring a Cu 5 cluster supported on a MoS 2 monolayer with an S monovacancy (Cu 5 @MoS 2 ). Our results revealed that one Cu atom of the Cu 5 cluster was embedded into the framework of the defective MoS 2 monolayer, while the other four Cu atoms form a square-like island over the substrate surface. Interestingly, the C–C coupling between two *CO species can easily occur on the unique square-like active site with a low kinetic barrier of 0.56 eV to form the key *C 2 O 2 intermediate, which can then be hydrogenated to the C 2 H 4 product with a very low limiting potential (–0.32 eV). Significantly, alkaline conditions (pH = 13) are beneficial to further promote C 2 H 4 synthesis. Finally, our work may offer a new avenue to precisely modulate the structures of Cu clusters for converting CO 2 into high-value target products.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2025

Support modification by phosphonic acid ligands controls ethylene hydroformylation on single-atom rhodium sites

To investigate the ability of surface-bound ligands to control activity toward ethylene hydroformylation, we modified site-isolated Rh 1 /TiO 2 with a series of substituted benzyl phosphonic acids. We found that modification of the support by phosphonic acids reduced break-in times for hydroformylation by 4× and increased absolute hydroformylation activity by up to 18× compared to unmodified catalyst at 150 °C. All functionalized catalysts improved hydroformylation activity by at least 9× and improved selectivity by between 7× and 60× relative to the unmodified catalyst. Carbon monoxide probe–molecule spectroscopy indicated that the enhancements in activity among modified samples were due to changes in the local environment of the active Rh site. Specifically, the bite angle of adsorbed carbon monoxide, as determined from infrared spectra, correlated with hydroformylation activity. These findings demonstrate that Rh 1 active sites are highly sensitive to modification of the support with organic ligands.

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

Formation of tungsten ethylidene complexes from diethyl complexes through a proton-catalyzed rearrangement of ethylene

Here, W(NAr) 2 Et 2 (Ar = 2,6-diisopropylphenyl) reacts with two equivalents of R F9 OH (OR F9 = OC(CF 3 ) 3 ) to yield W(NAr)(ArNH 2 )(OR F9 )2(C 2 H 4 ) complexes and ethane. In solution W(NAr)(ArNH 2 )(OR F9 ) 2 (C 2 H 4 ) decomposes to give R F9 OH, ethane, W(NAr)(OR F9 ) 2 (C 2 H 4 ), and W(NAr)(NHAr′)(ArNH 2 )(OR F9 ), in which Ar′ contains a dehydrogenated isopropyl group (Ar′ = (2-i-Pr)(6-CMe=CH 2 )C 6 H 3 ) coordinated to the metal. On a similar time scale W(NAr)(OR F9 ) 2 (CHCH 3 ) complexes are formed from W(NAr)(OR F9 ) 2 (C 2 H 4 ) through an ArNH 2 -catalyzed rearrangement of the ethylene ligand. W(NAr)(NHAr′)(ArNH 2 )(OR F9 ) reacts with cyclohexene to form methylenecyclohexene and complexes that contain an NHAr″ ligand where Ar″ is a disubstituted (methyl/aryl) alkylidene, (2-i-Pr)(6-CMe)C 6 H 3 ) that is tethered to the metal through the amido nitrogen. In contrast to W(NAr)(ArNH 2 )(OR F9 ) 2 (C 2 H 4 ), analogous OR F6 (OCMe(CF 3 ) 2 ) and OR F3 (OCMe 2 (CF 3 )) complexes are relatively stable at 22 °C.

Maji, Milan [University of California, Riverside, ↗
DOE OSTI2021

Probing the thermodynamics and kinetics of ethylene carbonate reduction at the electrode–electrolyte interface with molecular simulations

Understanding the formation of the solid-electrolyte interphase (SEI) in lithium-ion batteries (LIBs) is an ongoing area of research due to its high degree of complexity and the difficulties encountered by experimental studies. Herein, we investigate the initial stage of SEI growth, the reduction reaction of ethylene carbonate (EC), from both a thermodynamic and kinetic approach with theory and molecular simulation. We employed both the potential distribution theorem (PDT) and the SMD implicit solvent model to EC solvation for the estimation of reduction potentials of Li$^+$, EC, and Li$^+$-solvating EC (s-EC), as well as reduction rate constants of EC and s-EC. We find that solvation effects greatly influence these quantities of interest, particularly the Li$^+$/Li reference electrode potential in EC solvent. Further, we also compute the inner- and outer-sphere reorganization energies for both EC and s-EC at the interface of liquid EC and a hydroxyl-terminated graphite surface, where total reorganization energies are predicted to be 76.6 and 88.9 kcal/mol, respectively. With the computed reorganization energies, we estimate reduction rate constants across a range of overpotentials and show that EC has a larger electron transfer rate constant than s-EC at equilibrium, despite s-EC being more thermodynamically favorable. Furthermore, this manuscript demonstrates how ion solvation effects largely govern the prediction of reduction potentials and electron transfer rate constants at the electrode-electrolyte interface.

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

In situ saxs characterization of thermoresponsive behavior of a poly(ethylene glycol)-graft-(poly(vinyl caprolactam)-co-poly(vinyl acetate)) amphiphilic graft copolymer

In this work, we report the thermoresponsive assembly and rheology of an amphiphilic thermosensitive graft copolymer, poly(ethylene glycol)-graft-(poly(vinyl caprolactam)-co-poly(vinyl acetate)) (commercial name Soluplus ® ), which has been investigated for potential biomedical applications. It has received attention due to is ability to solubilize hydrophobic drugs and for its thickening behavior close to body temperature. Through use of the synchrotron at Brookhaven National Lab, and collaboration with the department of energy, the nanoscale structure and properties can be probed in greater detail. Soluplus ® undergoes two structural changes as temperature is increased; the first, a concentration independent change where samples become turbid at 32 °C. Increasing the temperature further causes the formation of physically associated hydrogels. This sol-gel transition is concentration dependent and occurs at 32 °C for 40 wt% samples, and increases to 42 °C for 10 wt% samples. From variable temperature SAXS characterization micelles of 20–25 nm in radius can be seen and maintain their size and packing below 32 °C. A gradual increase in the aggregation of micelles corresponding to a thickening of the material is also observed. Close to and above the gelation temperature, micelles collapse and form a physically associated 3D network. A model is proposed to explain these physical effects, where the poly(vinyl caprolactam) group transitions from the hydrophilic corona at room temperature to the hydrophobic core as temperature is increased.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Production and validation of scintillating structural components from low-background Poly(ethylene naphthalate)

Poly Ethylene Naphthalate (PEN) is an industrial polymer plastic which is investigated as a low background, transparent, scintillating and wavelength shifting structural material. PEN scintillates in the blue region and has excellent mechanical properties both at room and cryogenic temperatures. Thus, it is an ideal candidate for active structural components in experiments for the search of rare events like neutrinoless double-beta decay or dark matter recoils. Such optically active structures improve the identification and rejection efficiency of backgrounds events, like this improving the sensitivity of experiments. This paper reports on the production of radiopure and transparent PEN plates These structures can be used to mount germanium detectors operating in cryogenic liquids (LAr, LN). Thus, as first application PEN holders will be used to mount the Ge detectors in the LEGEND-200 experiment. The whole process from cleaning the raw material to testing the PEN active components under final operational conditions is reported.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Group VII ethylene response factors forming distinct regulatory loops mediate submergence responses

Group VII ethylene response factors (ERFVIIs), whose stability is oxygen concentration-dependent, play key roles in regulating hypoxia response genes in Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) during submergence. To understand the evolution of flooding tolerance in cereal crops, we evaluated whether Brachypodium distachyon ERFVII genes (BdERFVIIs) are related to submergence tolerance. We found that three BdERFVIIs, BdERF108, BdERF018, and BdERF961, form a feedback regulatory loop to mediate downstream responses. BdERF108 and BdERF018 activated the expression of BdERF961 and PHYTOGLOBIN 1 (PGB1), which promoted nitric oxide turnover and preserved ERFVII protein stability. The activation of PGB1 was subsequently counteracted by increased BdERF961 accumulation through negative feedback regulation. Interestingly, we found that OsERF67, the orthologue of BdERF961 in rice, activated PHYTOGLOBIN (OsHB2) expression and formed distinct regulatory loops during submergence. Overall, the divergent regulatory mechanisms exhibited by orthologs collectively offer perspectives for the development of submergence-tolerant crops.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Detection of diffusion limited oxidation in thermally aged ethylene propylene rubber cable insulation material

The lifetime prediction of electrical cable insulation in nuclear power plants (NPPs) is primarily based on accelerated aging. Polymeric insulation exposed to accelerated aging at high temperatures may demonstrate diffusion limited oxidation (DLO) where oxygen within the material is consumed faster than can be supplied by diffusion from the surrounding air. This situation leads to equilibrium oxidation at the exposed surfaces and limited oxidation away from the surfaces. Therefore, DLO results in a heterogeneously aged material which can lead to underestimation of lifetime for in-service cable insulation. In this study, the presence of inhomogeneous aging caused by DLO was evaluated on cross-sectioned cable insulation specimens made of ethylene propylene rubber (EPR). The studies were performed on thermally aged specimens (165 °C, 1 day and 165 °C, 16 days) using local measurement techniques including nanoindentation, micro-Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) - energy dispersive spectroscopy (EDS). All the results indicate some degree of heterogenous aging, with 165 °C, 16 days, aging demonstrating highest degree of oxidative degradation on the inside edges presumably caused due to copper catalyzed oxidation.

Pallaka, Madhusudhan Reddy↗
DOE OSTI2025

Effect of Transverse Compression on the Dielectric Breakdown of Power Cable with Ethylene Propylene Rubber Insulation

Understanding of the failure mechanisms of submarine dynamic power cables (SDPC) is critical for innovative design to meet the 2035 cost reduction target of U.S. DOE Floating Offshore Wind Shot. This is important because the current design suffers a significant failure rate in the field. This project explored a multiphysics approach and conducted systematic electro-thermo-mechanical (ETM) experimental study on the power cores extracted from a 15 kV power cable. The power cable had three cores of copper conductor and ethylene propylene rubber (EPR) insulation. An ETM testing system with transverse compression capability was developed. Mechanical loading induced dielectric breakdown. Increasing temperature from room temperature (RT, 22 degrees Celsius) to 90 degrees Celsius resulted in the 67% decrease in the failure mechanical load as defined by the dielectric breakdown. With the same temperature rise, the creep mechanical load was reduced by 70% at a given dielectric breakdown time. The post-test measurement revealed an impressive recovery of electrical resistance, although the dielectric breakdown occurred in the ETM test that would not be captured without the use of ETM testing.

Wang, Hong [ORNL] (ORCID:0000000201730545)↗
DOE OSTI2025

Nickel promotes selective ethylene epoxidation on silver

Over the last 80 years, chlorine (Cl) has been the primary promoter of the ethylene epoxidation reaction valued at ~40 billion USD per year, providing a ~25% selectivity increase over unpromoted silver (Ag) (~55%). Promoters such as cesium, rhenium, and molybdenum each add a few percent of selectivity enhancements to achieve 90% overall, but their codependence on Cl makes optimizing and understanding their function complex. Here, we took a theory-guided, single-atom alloy approach to identify nickel (Ni) as a dopant in Ag that can facilitate selective oxidation by activating molecular oxygen (O 2 ) without binding oxygen (O) too strongly. Surface science experiments confirmed the facile adsorption/desorption of O 2 on NiAg, as well as demonstrating that Ni serves to stabilize unselective nucleophilic oxygen. Supported Ag catalyst studies revealed that the addition of Ni in a 1:200 Ni to Ag atomic ratio provides a ~25% selectivity increase without the need for Cl co-flow and acts cooperatively with Cl, resulting in a further 10% initial increase in selectivity.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Selective Plasticization of Poly (ethylene oxide) (PEO) Block in Nanostructured Polystyrene– PEO– Polystyrene Triblock Copolymer Electrolytes

The plasticization of a polymer electrolyte usually promotes its ionic conductivity but decreases its storage modulus due to the increased polymer chain flexibility. Herein, we show that such a tradeoff between the ionic conductivity and the mechanical robustness of the polymer electrolyte can be alleviated by selective plasticization of the ion-conductive block, such as poly(ethylene oxide) (PEO) in a polystyrene (PS)– PEO–PS block copolymer (SEO) electrolyte using an ether type plasticizer, tetraethylene glycol dimethyl ether (TEGDME). In this work, at maximum plasticizer loading, the room temperature ionic conductivity increases by up to 3 orders, whereas the storage modulus, G' reduces to half, is still on the order of 10 2 MPa. At above the melting temperature of the PEO block, the dynamic storage modulus, G' of the plasticized membrane surpasses its dry PS-PEO-PS counterpart. Such a phenomenon results from that, a) TEGDME co-crystallizes with PEO to promote its crystallinity and hence the storage modulus, b) TEGDME swells the amorphous PEO phase to enhance the polymer chain segmental mobility and hence ionic conductivity, and c) the PS phase remains intact from TEGDME to keep the SEO elastic.

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

Communication—First-Principles Simulations of LiPF 6 Decomposition in Ethylene Carbonate-Based Electrolytes

We revisit a theoretical result by Okamoto (2013 Journal of The Electrochemical Society , 160 , A404) who calculated the energy barrier for the decomposition of lithium hexafluorophosphate (LiPF 6 ) into LiF + PF 5 when solvated in Ethylene carbonate (EC)-based electrolyte. Using different numerical techniques to discretize the Density Functional Theory (DFT) equations, and different continuum solvation models with the same dielectric constant, our results largely confirm the original calculation. However, simulations with a higher dielectric permittivity value, closer to that of EC, show a lower energy barrier. More importantly, First-Principles simulations with an explicit solvent show a substantially lower energy barrier.

25 ENERGY STORAGE↗
DOE OSTI2025

Confocal Raman Microscopy for Measuring In Situ Temperature-Dependent Structural Changes in Poly(Ethylene Oxide) Thin Films

Crystallization from the melt is a critical process governing the properties of semi-crystalline polymeric materials. While structural analyses of melting and crystallization transitions in bulk polymers have been widely reported, in contrast, those in thin polymer films on solid supports have been underexplored. Herein, in situ Raman microscopy and self-modeling curve resolution (SMCR) analysis are applied to investigate the temperature-dependent structural changes in poly(ethylene oxide) (PEO) films during melting and crystallization phase transitions. By resolving complex overlapping sets of spectra, SMCR analysis reveals that the thermal transitions of 50 µm thick PEO films comprise two structural phases: an ordered crystalline phase and a disordered amorphous phase. The ordered structure of the crystalline PEO film entirely disappears as the polymer is heated; conversely, the disordered structure of the amorphous PEO film reverts to the ordered structure as the polymer is cooled. Broadening of the Raman bands was observed in PEO films above the melting temperature (67 °C), while sharpening of bands was observed below the crystallization temperature (45 °C). The temperatures at which these spectral changes occurred were in good agreement with differential scanning calorimetry (DSC) measurements, especially during the melting transition. The results illustrate that in situ Raman microscopy coupled with SMCR analysis is a powerful approach for unraveling complex structural changes in thin polymer films during melting and crystallization processes. Furthermore, we show that confocal Raman microscopy opens opportunities to apply the methodology to interrogate the structural features of PEO or other surface-supported polymer films as thin as 2 µm, a thickness regime beyond the reach of conventional thermal analysis techniques.

Koh, Miharu [Department of Chemistry, University o↗
DOE OSTI2022

Atomistic Materials Modeling of High-Pressure Hydrogen Interactions in Ethylene Propylene Diene Monomer (EPDM) Rubber

Elastomeric rubbers serve a vital role as sealing materials in the hydrogen storage and transport infrastructure. With applications including O-rings and hose-liners, these components are exposed to pressurized hydrogen at a range of temperatures, cycling rates, and pressure extremes. Cyclic (de)pressurization is known to degrade these materials through the process of cavitation. This readily visible failure mode occurs as a fracture or rupture of the material and is due to the oversaturated gas localizing to form gas bubbles. Computational modeling in the Hydrogen Materials Compatibility Program (H-Mat), co-led by Sandia National Laboratories and Pacific Northwest National Laboratory, employs multi-scale simulation efforts to build a predictive understanding of hydrogen-induced damage in materials. Modeling efforts within the project aim to provide insight into how to formulate materials that are less sensitive to high-pressure hydrogen-induced failure. In this document, we summarize results from atomistic molecular dynamics simulations, which make predictive assessments of the effects of compositional variations in the commonly used elastomer, ethylene propylene diene monomer (EPDM).

08 HYDROGEN↗
DOE OSTI2026

Sustainable Ethylene via Chemical Looping – Oxidative Dehydrogenation

This Phase I final report evaluates chemical looping–oxidative dehydrogenation as a lower-energy and cost-competitive alternative to conventional ethane steam cracking for ethylene production. The project combined catalyst development and experimental testing with process modeling, techno-economic analysis, and life-cycle assessment. Results indicate that the proposed process could improve olefin production, reduce energy use, and lower production costs, particularly when integrated with carbon capture and renewable electricity. The report also identifies remaining technical, environmental, and safety considerations and presents a technology maturation plan focused on longer-term catalyst evaluation and advancement toward pilot-scale demonstration.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Hybrid Large Eddy Simulation/Reynolds-Averaged Navier–Stokes Analysis of a Premixed Ethylene-Fueled Dual-Mode Scramjet Combustor

Hydrocarbon fuels offer optimal high energy per volume for scramjet applications for sustained hypersonic flight but require additional residence time due to slower ignition delays (compared with hydrogen fuel). The injection of ethylene at the start of the isolator of a dual-mode scramjet combustor, operating in ramjet mode, allows sufficient mixing to achieve efficient premixed turbulent combustion. A cavity flameholder anchors the flame, supplying sufficient radicals to sustain a stable flame in the high-speed environment. This work investigates flame structure and stabilization limits of a new configuration with a scaled-down cavity embedded in the flow path of the combustor with a strut and insert. The cavity is reduced in size by one-third to enable eventual direct numerical simulations of the flame stabilization process. This work, however, focuses on modeling the full isolator/combustor geometry using a hybrid large eddy simulation/Reynolds-averaged Navier–Stokes simulation strategy. Additionally, particle image velocimetry, planar laser-induced fluorescence, coherent anti-Stokes Raman spectroscopy, and pressure measurements are compared with numerical predictions to analyze and characterize the conditions within the combustor, including flame structure, flow velocities, species composition, and wall pressure. An adjustable air throttle in the extender is able to control the placement of the shock train in the isolator and maintain a stable flame at various equivalence ratios. The simulations show reasonably good agreement with the experimental scalar and velocity data and predict a flame angle consistent with premixed turbulent flame-speed correlations.

42 ENGINEERING↗
DOE OSTI2024

Effect of Zwitterionic Additives on Solvation and Transport of Sodium and Potassium Cations in (Ethylene Oxide)10: A Molecular Dynamics Simulation Study

Sodium- (Na + ) and potassium- (K + ) ion batteries are cost-effective alternatives to lithium-ion (Li + ) batteries due to the abundant sodium and potassium resources. Solid polymer electrolytes (SPEs) are essential for safer and more efficient Na + and K + batteries because they often exhibit low ionic conductivity at room temperature. While zwitterionic (ZW) materials enhance Li+ battery conductivity, their potential for Na + and K + transport in batteries remains unexplored. In this study, we investigated the effect of three ZW molecules (ChoPO4, i.e., 2-methacryloyloxyethyl phosphorylcholine, ImSO3, i.e., sulfobetaine ethylimidazole, and ImCO2, i.e., carboxybetaine ethylimidazole) on the dissociation of Na + and K + coordination with ethylene oxide (EO) chains in EO-based electrolytes through molecular dynamics simulations. Our results showed that ChoPO4 possessed the highest cation–EO10 dissociation ability, while ImSO3 exhibited the lowest. Such dissociation ability correlated with the cation–ZW molecule coordination strength: ChoPO4 and ImSO3 showed the strongest and the weakest coordination with cations. However, the cation–ZW molecule coordination could slow the cationic diffusion. The competition of these effects resulted in accelerating or decelerating cationic diffusion. Our simulated results showed that ImCO2 enhanced Na + diffusion by 20%, while ChoPO4 and ImSO3 led to a 10% reduction. For K + , ChoPO4 reduced its diffusion by 40%, while ImCO2 and ImSO3 caused a similar decrease of 15%. These findings suggest that the ZW structure and the cationic size play an important role in the ionic dissociation effect of ZW materials.

25 ENERGY STORAGE↗