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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Preactivated zeolite nanosheet plate-tiled membrane on porous PVDF film: Synthesis and study of proton-selective ion conduction

Preactivated MFI zeolite nanosheet plates (ZNPs) with large areas (~2.0 × 2.0 μm 2 ) and nanometer thicknesses (~60 nm) were prepared directly in liquid-dispersed state. The individual ZNP was a stack of 4-nm-thick single crystalline zeolite nanosheets (ZNs) interlinked by Si–O–Si bonds between neighboring ZN surfaces. The dispersed open-pore ZNPs allowed formulating suspensions for tiling ZNP membranes on polymer substrates without requiring post-coating activation. A pinhole-free ZNP-tiled (ZNPT) membrane has been achieved on macroporous PVDF film by a self-repairing vacuum-assisted filtration coating method. The resultant ZNPT layer was ~500 nm-thick consisting of about 7 ZNP layers with inter-ZNP width and inter-ZNP entrance porosity around 9 nm and 2%, respectively. The ZNPT-PVDF membrane exhibited high selectivity to proton transport over vanadyl ion and low resistances to proton conduction in aqueous solutions. The membrane also demonstrated to function as an efficient ion separator for the vanadium redox flow battery. The reported synthesis of preactivated ZNP suspension may overcome the major hurdle to realizing polymer-supported ZN membranes, which is the inefficiency of existing methods in obtaining readily dispersible open-pore ZNs. Finally, the ZNPT-PVDF membrane can be a more affordable and sustainable alternative to the Nafion-based ion separation membranes.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Charge Concentration Limits the Hydrogen Evolution Rate in Organic Nanoparticle Photocatalysts

Colloidal organic nanoparticles have proven to be a promising class of photocatalyst for performing the Hydrogen Evolution Reaction (HER) due to their dispersibility in aqueous environments, their strong absorption within the visible region, and the tunabilty of their component materials' redox potentials. Currently, there is little understanding of how charge generation and accumulation in organic semiconductors change when these materials are formed into nanoparticles that share a high interfacial area with water, nor is it known what mechanism limits the hydrogen evolution efficiency in recent reports on organic nanoparticle photocatalysts. Herein, we use Time-Resolved Microwave Conductivity to study aqueous-soluble organic nanoparticles and bulk thin films composed of various blend ratios of the non-fullerene acceptor EH-IDTBR and conjugated polymer PTB7-Th and examine the relationship between composition, interfacial surface area, charge carrier dynamics, and photocatalytic activity. We quantitatively measure the rate of Hydrogen Evolution Reaction by nanoparticles composed of various donor:acceptor blend ratio compositions and find that the most active blend ratio displays a Hydrogen Quantum Yield of 0.83% per photon. Moreover, we find that nanoparticle photocatalytic activity corresponds directly to charge generation, and that nanoparticles have 3x more long-lived accumulated charges relative to bulk samples of the same material composition. Here these results suggest that, under our current reaction conditions, with approximately 3x solar flux, catalytic activity by these nanoparticles is limited by the concentration of electrons and holes in operando and not a finite number of active surface cites or the catalytic rate at the interface. This provides a clear design goal for the next generation of efficient photocatalytic nanoparticles.

08 HYDROGEN↗
DOE OSTI2026

Garnet/PVDF-HFP Hybrid Membranes for Li-Metal Batteries: Cooperative Research and Development Final Report, CRADA Number CRD-19-00807

Hazen Research, Inc., in collaboration with University of Colorado, Boulder (CU-B) and National Renewable Energy Laboratory (NREL), will develop and demonstrate a ceramic-polymer hybrid membrane based on garnet (Li7La3Zr2O12) and PVDF (Poly Vinylidene Fluoride)-HFP (Hexafluoropropylene) adaptable to Li-metal anodes. Under this CRADA, NREL will test the developed membranes providing feedback and advice to demonstrate hybrid membranes with Li-ion conductivity >10-4 S/cm at room temperature that are stable with Li-metal, followed by demonstration of full cells with Li-metal anode.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2021

Trace explosive residue detection of HMX and RDX in post-detonation dust from an open-air environment

Explosives are often used in industry, geology, mining, and other applications, but it is not always clear what remains after a detonation or the fate and transport of any residual material. The goal of this study was to determine to what extent intact molecules of high explosive (HE) compounds are detectable and quantifiable from post-detonation dust and particulates in a field experiment with varied topography. We focused on HMX (1,3,5,7-Tetranitro-1,3,5,7-tetrazocane), which is less studied in field detonation literature, as the primary explosive material and RDX (1,3,5-Trinitroperhydro-1,3,5-triazine) as the secondary material. The experiment was conducted at Site 300, Lawrence Livermore National Laboratory’s Experimental Test Site, in California, USA. Two 20.4 kg and one 40.8 kg above ground explosions (primarily comprised of LX-14, an HMX-based polymer-bonded high explosive) were detonated on an open-air firing area on separate days. The complex terrain of the firing area (e.g., buildings, berm, low-height obstacles) was advantageous to study HE deposition in relation to plume dynamics. Three types of samples were collected up to 100 m away from each shot: surface swipes of aluminum plates, surface swipes of fixed objects, and filters from air samples. We used atmospheric flow tube-mass spectrometry (AFT-MS) to quantify picogram levels of molecular residue of HE material in the post-detonation dust. An aliquot of sample extract in methanol (e.g., 1 µL of 0.5 mL) was placed onto a resistive material and then thermally desorbed into the AFT-MS. We successfully detected and quantified both HMX and RDX in many of the samples. Based on mass (pg) detected and solution dilution, we back-calculated the mass collected on the swipe or filter (ng per sample). The aerial distribution of molecular residue was consistent with the path of the plume, which was strongly determined by wind speed and direction at the time of each shot. The quantity of material detected appeared to correlate more with distance from the shot and the wind conditions than with shot size. This study demonstrates that the picogram detection levels of AFT-MS are well-suited for quantification of analytes (e.g., HMX and RDX) in environmental samples.

atmospheric flow tube-mass spectrometry (AFT-MS), ↗
DOE OSTI2021

Relationship between microstructure evolution and properties enhancement of carbon nanotubes‐filled polybutylene terephthalate/polypropylene blends induced by thermal annealing

Abstract Thermal annealing induced microstructure evolution and properties enhancement of polybutylene terephthalate/polypropylene/carbon nanotubes (PBT/PP/CNTs) nanocomposites was methodically investigated. The electrical conductive PBT/PP/CNTs nanocomposites with a low percolation threshold were obtained by simple melt blending due to the selective location of the CNTs in PBT phase and the formation of the double percolation structure. Thermal annealing further remarkably decreased the volume resistivity of the nanocomposites, with the maximum reduction of seven orders of magnitude. Scanning electron microscope observation and rheology tests demonstrated that the relatively large CNTs agglomerates were redistributed to build more homogeneous CNTs networks after annealing. The phase coalescence during annealing promoted the formation of the more perfect co‐continuous structure. These phenomena helped to enhance the electrical conductivity of the nanocomposites. Flexural properties of the nanocomposites were also enhanced after annealing, which might be due to the more effective stress transfer between the polymer and CNTs induced by the reconstructed CNTs networks. The nanocomposites obtained in this study possess excellent electrical and mechanical properties, which can be applied to the fields of sensors, electromagnetic interference shielding, anti‐static materials, and so forth.

Shang, Mengyao↗
DOE OSTI2023

Theoretical Examination of the Hydroxide Transport in Cobaltocenium-Containing Polyelectrolytes

Polymers incorporating cobaltocenium groups have received attention as promising components of anion-exchange membranes (AEMs), exhibiting a good balance of chemical stability and high ionic conductivity. In this work, we analyze the hydroxide diffusion in the presence of cobaltocenium cations in an aqueous environment based on the molecular dynamics of model systems confined in one dimension to mimic the AEM channels. In order to describe the proton hopping mechanism, the forces are obtained from the electronic structure computed at the density-functional tight-binding level. We find that the hydroxide diffusion depends on the channel size, modulation of the electrostatic interactions by the solvation shell, and its rearrangement ability. Hydroxide diffusion proceeds via both the vehicular and structural diffusion mechanisms with the latter playing a larger role at low diffusion coefficients. The highest diffusion coefficient is observed under moderate water densities (around half the density of liquid water) when there are enough water molecules to form the solvation shell, reducing the electrostatic interaction between ions, yet there is enough space for the water rearrangements during the proton hopping. Furthermore, the effects of cobaltocenium separation, orientation, chemical modifications, and the role of nuclear quantum effects are also discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Characterization of the structure and chemistry of the solid–electrolyte interface by cryo-EM leads to high-performance solid-state Li-metal batteries

Solid-state lithium-metal (Li 0 ) batteries are gaining traction for electric vehicle applications because they replace flammable liquid electrolytes with a safer, solid-form electrolyte that also offers higher energy density and better resistance against Li dendrite formation. Solid polymer electrolytes (SPEs) are highly promising candidates because of their tunable mechanical properties and easy manufacturability; however, their electrochemical instability against lithium metal (Li 0 ), mediocre conductivity, and poorly understood Li 0 /SPE interphases have prevented extensive application in real batteries. In particular, the origin of the low Coulombic efficiency (CE) associated with SPEs remains elusive, as the debate continues as to whether it originates from unfavored interfacial reactions or lithium dendritic growth and dead lithium formation. In this work, we use state-of-the-art cryo-electromicroscopy (cryoEM) imaging and spectroscopic techniques to characterize the structure and chemistry of the interface between Li 0 and a polyacrylate-based SPE. Contradicting the conventional knowledge, we find that no protective interphase forms, owing to the sustained reactions between deposited Li dendrites and polyacrylic backbones and succinonitrile plasticizer. Due to the reaction induced volume change, large amounts of cracks form inside the Li dendrites with a stress corrosion-cracking behavior, indicating that Li0cannot be passivated in this SPE system. Based on this observation, we then introduce additive engineering leveraging on the knowledge of liquid electrolytes, and demonstrate that the Li 0 surface can be effectively protected against corrosion using fluoroethylene carbonate (FEC), leading to densely packed Li 0 domes with conformal and stable solid-electrolyte interphases (SEIs) films. Owing to the high room temperature ionic conductivity of 1.01 mS/cm -1 , the high transference number of 0.57 and the stabilized lithium electrolyte interface, this improved new SPE delivers an excellent lithium plating/stripping CE of 99% and 1800 hours of stable cycling in Li||Li symmetric cells (0.2 mA/cm -2 , 1mAh/cm -2 ). Furthermore, this improved cathodic stability along with the high anodic stability enables record high cycle life of >2000 cycles for Li||LiFePO 4 and >400 cycles for Li||LiCoO 2 full cells.

25 ENERGY STORAGE↗
DOE OSTI2024

STUDIES ON PIPELINE POLYETHYLENES IN HYDROGEN GAS ENVIRONMENTS USING IN-SITU AND EX-SITU CHARACTERIZATION METHODS

Polymeric materials are commonplace in the natural gas infrastructure as distribution pipes, coatings, seals, and gaskets. Under the auspices of the U.S. Department of Energy HyBlend program, one of the means to reduce greenhouse gas emissions is with replacing natural gas, either partially or completely, with hydrogen. This approach makes it imperative that we conduct near-term and long-term materials compatibility research in these relevant environments. Insights into the effects of hydrogen and hydrogen gas blends on polymer integrity can be gained through both ex-situ and in-situ analytical methods. Our work represented here highlights a study of the behavior of pipeline polyethylene (PE) materials, including HDPE (Dow 2490 and GDB50) and MDPE (Ineos and legacy Dupont Aldyl A), when exposed to hydrogen by means of in-situ X-ray scattering and ex-situ Raman spectroscopy techniques. Samples were tested in ex-situ hydrogen and argon gas environments and in-situ hydrogen environments to identify differences due to permeation and solubility of these gases. These methods complemented each other because Raman spectroscopy could capture permanent effects after materials were removed from gaseous environments, and in-situ X-ray scattering analysis collected real-time data to elucidate the impact of the gas environment on polymer microstructure. Data collected revealed that the aforementioned polymers did not show significant changes in crystallinity and microstructure under the exposure conditions tested. Our findings from these studies will help establish real-time effects caused by hydrogen gas transport through pipeline polyethylenes by way of its influence on polymer structure and chemistry, which is directly related to pipeline mechanical strength and longevity of service.

Hydrogen materials compatibility, Natural gas pipe↗
DOE OSTI2023

Crosslinking of loose insulating powders

Described herein are materials and methods useful in the field of insulation, including building materials, refrigeration, cryogenics, and shipping, amongst others. Advantageously, the provided materials and method provide low thermal conductivities and increased mechanical strength, allowing for efficient insulating in a diverse range of applications. The provided materials and methods include individual particles connected by a polymer network that links individual particles and may include hollow or evacuated capsules and various strengthening agents.

Simpson, Lin Jay↗
DOE OSTI2020

Reversible Changes in the Grain Structure and Conductivity in a Block Copolymer Electrolyte

Here, we study the phase behavior of a triblock organic–inorganic hybrid copolymer, poly(polyhedral oligomeric silsesquioxane)-b-poly(ethylene oxide)-b-poly(polyhedral oligomeric silsesquioxane) (POSS-PEO-POSS)/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt mixture, as a function of temperature. The polymer exhibits a lamellar morphology both in the neat state and in the presence of salt. However, the average grain size increases substantially when the electrolyte is heated above 113 °C. The grain structure of this sample changes reversibly with temperature, that is, smaller grains reappear when the electrolyte is cooled below 113 °C. While annealing block copolymers at high temperatures often leads to an increase in the grain size, this change is generally irreversible. The reason for the reversible change in the grain structure of the POSS-PEO-POSS/LiTFSI electrolyte is discussed. The ionic conductivity of the electrolyte also exhibits reversible changes in this temperature window. Knowledge of the grain structure is crucial for understanding ion transport in nanostructured electrolytes.

25 ENERGY STORAGE↗
DOE OSTI2025

Water Dynamics of Superacid Aromatic Proton Exchange Membranes for Fuel Cell Applications

Proton exchange membranes (PEMs) with high conductivity are of critical importance for the development of fuel cells, electrolyzers, and other electrochemical technologies. In this research, poly(1,1,2,2-tetrafluoro-2-phenoxyethane-1-sulfonic acid) (PTPS) with an aromatic polymer main chain and a perfluorinated superacidic polymer side chain was synthesized. The water dynamics of PTPS were characterized across various length scales using a combination of Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) and compared with Nafion, a standard perfluorinated PEM, and sulfonated poly(ether sulfone) (SPES 40), an aromatic PEM without perfluorinated superacid side chains. The T 1 and T 2 relaxation times of water in the samples probed by NMR increase from SPES 40 to PTPS to Nafion, indicating that the local motion of the water molecules becomes faster. This trend corresponds well with the relative fraction of bulk-like water determined using FTIR. At larger length scales, the diffusion coefficient of water was characterized using pulsed-field gradient NMR (PFG-NMR). At a longer diffusion time (Δ = 100 ms), PTPS has a smaller diffusion coefficient compared with both Nafion and SPES 40, due to restricted diffusion, and this effect is also evident in the proton conductivity of the hydrated membranes. From this comparison, it is apparent that the aromatic backbone and side chain type greatly influence the water dynamics in PEMs at various length scales and the water dynamics significantly impact the bulk proton conductivity. These insights will lead to new designs for aromatic PEMs and help to identify bottlenecks in current materials.

25 ENERGY STORAGE↗
DOE OSTI2022

Crosslinked Polyethyleneimine Gel Polymer Interface to Improve Cycling Stability of RFBs

Redox flow batteries are considered a promising technology for grid energy storage. However, capacity decay caused by crossover of active materials is a universal challenge for many flow battery systems, which are based on various chemistries. In this paper, using the vanadium redox flow battery as an example, we demonstrate a new gel polymer interface (GPI) consisting of crosslinked polyethyleneimine with a large amount of amino and carboxylic acid groups introduced between the positive electrode and the membrane. The GPI functions as a key component to prevent vanadium ions from crossing the membrane, thus supporting stable long-term cycling. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were conducted to investigate the effect of GPI on the electrochemical properties of graphitic carbon electrodes (GCFs) and redox reaction of catholyte. X-ray photoelectron spectroscopy (XPS) and 1 H nuclear magnetic resonance (NMR) spectra demonstrated that the crosslinked GPI is chemically stable for 100 cycles without dissolution of polymers and swelling in the strong acidic electrolytes. Results from inductively coupled plasma mass spectrometry (ICP-MS), Fourier-transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray (EDX) spectroscopy proved that the GPI is effective in maintaining the concentration of vanadium species in their respective half-cells, resulting in improved cycling stability because of it prevents active species from crossing the membrane and stabilizes the oxidation states of active species.

Lim, Hyung-Seok↗
DOE OSTI2022

Coal polymer composites prepared by fused deposition modeling (FDM) 3D printing

Coal is a vital energy resource worldwide, but pollutants and greenhouse gases from its combustion cause environmental problems. To explore the non-combustion approach to use and valorize coal, anthracite and lignite were blended with polyamide 12 (PA 12) through FDM printing in this work and compared in the composites. By adding lignite, Young’s modulus improved with increasing loading to 50 wt% while tensile strength leveled off among the composites, compared to that of PA 12. By contrast, the addition of anthracite decreased the tensile performance at all loadings. Rheology tests and morphology analyses suggested that the interactions between fillers (anthracite and lignite) and PA 12 may cause differences in tensile properties. In addition, the printed lignite composites showed improved thermal conductivity (~ twofold), indicating lignite demonstrates the potential to build functional composites. This work provides a strategy to use lignite in composites by 3D printing for value-added products and reduces the demand for petroleum-based polymers. Overall, our approach diverts lignite from combustion processes and alleviates the negative impact of lignite use on the environment.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Electrocatalysis of Oxygen Reduction Reaction in a Polymer Electrolyte Fuel Cell with a Covalent Framework of Iron Phthalocyanine Aerogel

Carbon aerogels have been studied in the context of fuel cell electrodes mainly as catalyst support materials due to their high surface area, porosity, and electrical conductivity. Recently, aerogels composed solely of inorganic molecular complexes have shown to be promising materials for the electrocatalysis of oxygen reduction reaction (ORR). These aerogels consist of atomically dispersed catalytic sites. Herein, we report on the synthesis and characterization of an aerogel-based catalyst: iron phthalocyanine aerogel. It was synthesized by coupling of ethynyl-terminated phthalocyanine monomers and then heat-treated at 800 °C to increase its electrical conductivity and catalytic activity. Further, the aerogels reported here were tested as catalysts for ORR in acidic conditions for the first time and found to have a ultra-high number of atomically dispersed catalytic sites (7.11 × 10 20 sites g –1 ) and very good catalytic activity (E onset = 0.9 V vs RHE and TOF = 9.2 × 10 –3 e – s –1 site –1 at 0.8 V vs RHE). The iron phthalocyanine aerogel was also studied in a proton exchange membrane fuel cell, reaching a peak power density of 292 mW cm –2 and an open circuit voltage of 0.83 V.

25 ENERGY STORAGE↗
DOE OSTI2025

Enhanced dielectric insulation of biaxially oriented high temperature polyester films for capacitive energy storage

Biaxially oriented polypropylene (BOPP) films are widely used in dielectric capacitors due to their ultralow loss, high breakdown strength, and long lifetime. However, their poor temperature tolerance limits applications in emerging high-temperature environments such as wide-band-gap power electronics in electric vehicles. Here, we report significantly enhanced dielectric insulation properties of biaxially oriented poly(ethylene 2,6-naphthalate) (BOPEN) films compared to biaxially oriented poly(ethylene terephthalate) (BOPET) films, despite their similar semicrystalline morphologies. BOPEN exhibits higher DC and AC breakdown strengths and markedly extended lifetimes at elevated temperatures. For instance, at 120 °C, the DC Weibull lifetime of BOPEN exceeded that of BOPET by over two orders of magnitude and even surpassed that of BOPP. Through comprehensive analyses—leakage current, electric displacement-electric field loops, and thermally stimulated depolarization current—we attribute this superior performance to suppressed homocharge injection and conduction losses, enabled by the rigid naphthalene-based backbone in BOPEN that reduces dipole mobility and chain polarity. These findings underscore the potential of BOPEN as a next-generation polymer dielectric for high-temperature capacitor applications.

25 ENERGY STORAGE↗
DOE OSTI2024

Ion transport in composites of binary electrolyte and single ion conductor—A chronoamperometry study

Composite electrolytes for lithium batteries typically combine materials with very different mechanical properties and ionic transport mechanisms and the degree to which these two phases affect each other is not well understood. In this work we used numerical simulations and experiments to investigate the transport in composite electrolytes consisting of polyethylene oxide (PEO) with Lithium bis-triuoromethanesulfonimide (LiTFSI) and Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) lithium ion conducting glass-ceramic particles. In particular we are interested in how the introduction of a single ion conductor (SIC) changes the salt concentration gradients in the polymer electrolyte (PE) under applied potential. To study this, we performed numerical simulations and chronoamperometry experiments in electrolytes with different arrangements of the SIC and PE phases, i.e. layers and particulate composites. The results show that the particulate composites have the highest concentration gradients and take the longest time to reach steady state current. Furthermore, the high concentration gradient can be exacerbated by a high SIC/PE interfacial resistance. Finally, the best arrangement appears to have a layer of SIC impenetrable to anions in the polymer phase within the electrolyte membrane.

25 ENERGY STORAGE↗
DOE OSTI2025

The Role of Water Volume Fraction on Water Adsorption in Anion Exchange Membranes

Water absorption plays a key role in the performance of polymeric anion exchange membranes. It influences important properties such as ionic conductivity and mechanical strength and alters their performance as solid electrolytes in hydrogen electrochemical devices for energy conversion. However, computational approaches that address the relationship between the polymer design and the absorption process are scarce. In this work, we introduce a simple thermodynamic model to predict the water absorption isotherms of polyelectrolyte membranes in contact with a water vapor reservoir that incorporates the specific chemical design of the polymers. The model accurately predicts the water content and macrostructural properties of polynorbornene membranes as a function of the water activity and successfully captures the effect of various polymer design parameters. The energy of pairwise attractive interactions predicted by our model provides a means to interpret the absorption process at the molecular level. The model also reveals the most significant favorable and unfavorable contributions to the free energy and indicates that their balance is solely governed by the water volume fraction, regardless of the polymer design. This universal behavior leads to important implications in the search for better ion exchange membranes.

Zaldivar, Gervasio [New York University, Brooklyn,↗