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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Relationship of the Molecular Structure and Transport Properties of Imide-Based Lithium Salts of “Acetonitrile/Water-in-Salt” Electrolytes

“Water-in-salt” (WIS) electrolytes exhibit excellent safety and electrochemical performance. However, they possess high concentrations, relatively low diffusion coefficient, and high viscosity. “Acetonitrile/water in salt” (AWIS) electrolytes can overcome the disadvantages of WIS electrolytes. Under relatively low concentrations, AWIS electrolytes show good electrochemical performance comparable to WIS electrolytes and low conductivity. Herein, we investigate the relationship between the solvation structures and the transport properties using small-angle X-ray scattering and molecular dynamics simulation. We observed two solvation behaviors of AWIS: anions dissolved in acetonitrile forming small acetonitrile/anion clusters and additional water further dissolving the small acetonitrile/anion clusters. The introduction of acetonitrile weakens the water–solute interaction and enhances the cation–anion interaction, which results in an enhanced dynamical slowdown as the concentration increases. In conclusion, this work provides molecular-level understanding of the connection between two-stage solvation structures and transport properties for imide-based lithium salt solutions.

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

Ion Gating in Nanopore Electrode Arrays with Hierarchically Organized pH-Responsive Block Copolymer Membranes

Inspired by biological ion channels, artificial nanopore-based architectures have been developed for smart ion/molecular transport control with potential applications to iontronics and energy conversion. Advances in nanofabrication technology enable simple, versatile construction methods, and post-fabrication functionalization delivers nanochannels with unique ion transport-control attributes. Here, we characterize a pH-responsive, charge-selective dual-gating block copolymer (BCP) membrane composed of polystyrene-b-poly(4-vinylpyridine) (PS 48400 -b-P4VP 21300 ), capable of self-organizing into highly ordered nanocylindrical domains. Because the PS-b-P4VP membrane exhibits pH-dependent structural transitions, it is suitable for designing intelligent pH-gated biomimetic channels, for example, exhibiting on–off transport switching at pH values near the pK a of P4VP with excellent anion permselectivity at pH < pK a . Introducing the BCP membrane onto nanopore electrode arrays (BCP@NEAs) allows the BCP to serve as a pH-responsive gate controlling ion transfer into the NEA nanopores. Such selectively transported and confined ions are detected by using a 100 nm gap dual-ring nanoelectrode structure capable of enhancing current output by efficient redox cycling with an amplification factor >10 2 . In addition, BCP@NEAs exhibit extraordinary pH-gated ion selectivity, resulting in a 3380-fold current difference between anion and cation probes at pH 3.0. Furthermore, this hierarchically organized BCP-gated NEA system can serve as a template for the development of other stimulus-responsive ion gates, for example, those based on temperature and ligand gating, thus exploiting the intrinsic advantages of NEAs, such as enhanced sensitivity based on redox cycling, which may lead to technological applications such as engineered biosensors and iontronic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Supported Electrophilic Organoruthenium Catalyst for the Hydrosilylation of Olefins

A series of supported electrophilic organoruthenium complexes has been synthesized via surface organometallic chemistry (SOMC) techniques and applied to the selective hydrosilylation of olefins. The air-sensitive 16e - complex Cp*RuMes(PCy 3 ) (1) (Cp* = pentamethylcyclopentadienyl, Mes = mesityl) was synthesized by the treatment of Cp*RuCl(PCy 3 ) with mesityl Grignard MesMgBr. This species was chemisorbed onto sulfated zirconia SO 4 /ZrO 2 , but the resulting material was inactive toward cyclohexene hydrosilylation with phenylsilane. Instead, Cp*RuMes(PCy 3 ) was treated with phenylsilane (PhSiH 3 ) to provide a ruthenium disilyl hydride complex Cp*RuH(SiH 2 Ph) 2 (PCy 3 ) (3), which was fully characterized by NMR spectroscopy and single-crystal X-ray diffraction. Grafting this species onto SO 4 /ZrO 2 resulted in the formation of phenylsilane along with the surface electrophilic species [Cp*RuH(R)(X-SiHPh)(PCy 3 )] (R = H, O 3 S-O or O 3 Zr-O; 4a, 4b, X = O 3 S-O, and O 3 Zr-O, respectively) as the major species. Material 4 was characterized via a combination of spectroscopic techniques including dynamic nuclear polarization (DNP)-enhanced solid-state NMR spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray absorption spectroscopy (XAS), and density function theory (DFT) calculations. Further, capping the remaining acid sites on 4 with Me 3 Si-SiMe 3 provides 5, which significantly reduces side reactions, such as olefin isomerization and silane redistribution. Catalyst 5 is a highly robust and selective hydrosilylation catalyst and can be recycled up to 5 times without significant diminishment of activity. Exclusive anti-Markovnikov regiochemistry, cis-addition selectivity, and the inactivity of secondary and tertiary silanes provide support for the proposed Glaser-Tilley mechanism involving cationic ruthenium silylene species analogous to homogeneous systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1985

Dopant effect of yttrium and the growth and adherence of alumina on nickel-aluminum alloys

The atom superposition and electron delocalization molecular orbital theory and large cluster models have been employed to study cation vacancy diffusion in alpha-Al2O3 and the bonding of alpha-Al2O3 to nickel, aluminum, and yttrium surfaces. Al(3+) diffusion barriers in alpha-Al2O3 by the vacancy mechanism are in reasonable agreement with experiment. The barrier to Y(3+) diffusion is predicted to be much higher. Since addition of yttrium to transition metal alloys is known to reduce the growth rate and stress convolutions in protective alumina scales, this result suggests the rate-limiting step in scale growth is cation vacancy diffusion. This may partially explain the beneficial effect of yttrium dopants on scale adhesion. The theory also predicts a very strong bonding between alumina and yttrium at the surface of the alloy. This may also be important to the adhesion phenomenon. It is also found that aluminum and yttrium atoms bond very strongly to nickel because of charge transfer from their higher lying valence orbitals to the lower lying nickel s-d band.

Anderson, A. B.↗
DOE OSTI2022

Simultaneous Control of Pore-Space Partition and Charge Distribution in Multi-Modular Metal–Organic Frameworks

Here we report here a strategy for making anionic pacs type porous materials by combining pore space partition with charge reallocation. The method uses the first negatively charged pore partition ligand (2,5,8-tri-(4-pyridyl)-1,3,4,6,7,9-hexaazaphenalene, H-tph) that simultaneously enables pore partition and charge reallocation. Over two dozen anionic pacs materials have been made to demonstrate their excellent chemical stability and a high degree of tunability. Notably, Ni 3 -bdt-tph (bdt=1,4-benzeneditetrazolate) exhibits month-long water stability, while CoV-bdt-tph sets a new benchmark for C 2 H 2 storage capacity under ambient conditions for ionic MOFs. In addition to tunable in-framework modules, we show feasibility to tune the type and concentration of extra-framework counter cations and their influence on both stability and capability to separate industrial C 3 H 8 /C 3 H 6 and C 6 H 6 /C 6 H 12 mixtures.

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

Sequential separation of battery electrode materials and metal foils in aqueous media

To recycle high-value lithium-ion battery components, it is imperative to efficiently separate electrode materials from current collector foils and to separate cathodes from anodes. This study investigates the delamination behaviors of cathodes and anodes from their respective current collectors in aqueous media. Whereas anode films can easily detach from copper foils in water, the delamination of cathode films does not exhibit the same behavior in water; instead, the cation exchange reaction results in lithium leaching and aluminum corrosion in the presence of water. Here, a buffer solution with surfactant additives has been designed to prevent aluminum corrosion and to improve solution wetting behavior, thereby facilitating cathode delamination. The delamination difference enables the sequential recovery of electrode materials and metal foils at different separation stages, simplifying the traditionally intricate processes within a one-pot recovery system. The recovered materials retain their crystal structure and morphology, and there are no signs of aluminum corrosion or residues on the metal foils. The sequential separation technique achieves nearly 100% separation efficiency for electrode materials from metal foils and over 98% separation efficiency for cathode and anode materials.

25 ENERGY STORAGE↗
DOE OSTI2024

Electrochemical and Chemical Reactivities of Titanium Oxide-Based Materials with a Chloroaluminate Ionic Liquid Electrolyte for Aluminum Batteries

Here, by selecting three different types of electrode materials, we intended to better understand the Al 3+ intercalation chemistry of titanium oxide-based frameworks with an acidic chloroaluminate electrolyte. In agreement with previous reports, we confirmed that the native interstitial sites of anatase TiO 2 are less prone to accommodate Al 3 + than Li + or Na + ions, while introducing cationic vacancies largely increases the electrochemical storage capacity. Upon the first cycle, the highest reversible capacity, up to 277 mAh/g, was obtained for a hydrated layered structure featuring cationic vacancies. Total scattering data showed that the insertion of Al 3+ ions induced a strong distortion of the framework. In addition, combined 27 Al MAS NMR and DFT calculations revealed that in oxy-hydroxylated vacant sites, the coordination mode of Al 3+ ions depends on the arrangement of anions around vacancies inducing the occurrence of 4-, 5-, and 6-fold coordination modes. Further cycling experiments revealed a progressive capacity fading for all electrode materials. Using cyclic voltammetry on the used electrolyte, we evidenced that a partial dissolution has occurred, which is more pronounced for the layered hydrate compound, and that solubilized species are electrochemically active, giving rise to specific signatures in both CVs and galvanostatic experiments. Raman spectroscopy enabled us to characterize these species, which are derived from the Ti-Cl system. The solubilized species, however, eventually precipitated, as shown by a purple deposit observed on the separator and tentatively assigned to TiCl 3 , known to be insoluble in this medium. By providing further information on the Al 3+ intercalation chemistry and a better understanding of the electrochemical and chemical reactivities of electrode materials, this work will enable progress to be made in the development of aluminum-ion batteries.

Al3+-ion insertion chemistry↗
DOE OSTI2023

Deciphering the Olefin Isomerization-Polymerization Paradox of Palladium(II) Diimine Catalysts: Discovery of Simultaneous and Independent Pathways of Olefin Isomerization and Living Polymerization

This work elucidates a long-standing unexplained paradox commonly observed within the polymerization of α-olefin using palladium (Pd)(II)–diimine catalysts, in which isomerization and living polymerization of α-olefins are both observed. With a classical mechanistic understanding of these complexes, this behavior is often dismissed and interpreted as experimental error. Herein, we present a comprehensive mechanistic investigation into this phenomenon that supports the existence of a novel mechanistic pathway for Pd(II)–diimine complexes. Part one of the mechanistic study lays the foundation of the proposed mechanism, in which neutral Pd(II)–diimine complexes were found to exhibit a moderate to good catalytic activity for olefin isomerization of α-olefins despite the established notion that catalyst activation is required. Extensive experimental and computational studies reveal the possibility of a partial dissociation of the diimine ligand, which frees up one coordination site and enables coordination–insertion. This finding is significant as the coexistence of two reactive coordination sites at the palladium center becomes a valid proposal for the activated cationic Pd(II)–diimine complexes. In part two, we examined and validated the simultaneously observed α-olefin isomerization and living polymerization using the cationic Pd(II)–diimine catalyst, which supports the presence of two independent reaction pathways of isomerization and polymerization, respectively. Furthermore, the addition of a strong Lewis acid, such as AlCl 3 , accelerates the ligand dissociation and the consequential isomerization as it weakens the palladium–nitrogen bond through competitive binding. In part three, Lewis acid-triggered olefin isomerization-polymerization is employed to prepare living olefinic block copolymers and further synthesize novel polyolefin-polar block copolymers with unique architectures, distinct levels of branching, crystallinity, and polar functionality in a one-pot manner.

Catalysts↗
DOE OSTI2023

Highly efficient synthesis of zeolite chabazite using cooperative hydration-mismatched inorganic structure-directing agents

Chabazite (CHA type) zeolite is notoriously difficult to synthesize in the absence of organic structure-directing agents owing to long synthesis times and/or impurity formation. The ability to tailor organic-free syntheses of zeolites is additionally challenging due to the lack of molecular level understanding of zeolite nucleation and growth pathways, particularly the role of inorganic cations. In this study, we reveal that zeolite CHA can be synthesized using six different combinations of inorganic cations, including the first reported seed- and organic-free synthesis without the presence of potassium. We show that lithium, when present in small quantities, is an effective accelerant of CHA crystallization; and that ion pairings can markedly reduce synthesis times and temperatures, while expanding the design space of zeolite CHA formation in comparison to conventional methods utilizing potassium as the sole structure-directing agent. Herein, we posit the effects of cation pairings on zeolite CHA crystallization are related to their hydrated ionic radii. We also emphasize the broader implications for considering the solvated structure and cooperative role of inorganic cations in zeolite synthesis within the context of the reported findings for chabazite.

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

Multi-functionalized basic immobilized amine sorbents for removal of metal contaminants from wastewater

This disclosure provides polyamine sorbent compositions for the separation of metals from aqueous solutions. The polyamine sorbent compositions comprise a silica support, an aminosilane bound to the silica support, an epoxysilane bound to the silica support, and a polyamine where the polyamine is chemically tethered onto a solid silica support through via the epoxysilane. The polyamine may be further stabilized within the bulk sorbent through hydrogen bonding interactions with the aminosilane. The sorbent compositions resist leaching by H 2 O in an aqueous stream containing heavy oxyanion-based (and other) metals and demonstrate stability over a pH range of 2-14. The sorbent compositions are useful for the separation of metals from aqueous solutions. The cationic heavy metals are captured by the co-existing amine groups (—NH 2 , —NH, —N) from the polymeric network while additional metal capture capacity is derived from the introduction of a secondary silane linker.

Gray, McMahan L.↗
DOE OSTI2021

Decoupling Proton and Cation Contributions to Capacitive Charge Storage in Birnessite in Aqueous Electrolytes

Abstract Nanostructured birnessite is of interest as an electrode material for aqueous high power electrochemical energy storage as well as desalination devices. In neutral pH aqueous electrolytes, birnessite exhibits a capacitive response attributed to the adsorption of cations and protons at the outer surface and within the hydrated interlayer. Here, we utilize the understanding of proton‐coupled electron transfer (PCET) in buffered electrolytes to decouple the role of protons and cations in the capacitive charge storage mechanism of birnessite at neutral pH. We find that without buffer, birnessite exhibits primarily potential‐independent (capacitive) behavior with excellent cycling stability. Upon the addition of buffer, the capacity initially increases and the cyclic voltammograms become more potential‐dependent, features attributed to the presence of PCET with the birnessite. However, long‐term cycling in the buffered electrolyte leads to significant capacity fade and dissolution, which is corroborated through ex situ characterization. ReaxFF atomistic scale simulations support the observations that proton adsorption leads to birnessite degradation and that capacitive charge storage in birnessite is primarily attributed to cation adsorption at the outer surface and within the interlayer.

Saeed, Saeed↗
DOE OSTI2020

Harbinger of hysteresis in lithium-rich oxides: Anionic activity or defect chemistry of cation migration

In this work, we present findings on the mechanisms of hysteresis in lithium-rich cathode oxides. It is generally reported that the energy inefficiency, observed during electrochemical cycling of Li-rich electrodes, is a direct result of anion redox processes. Similarly, the coupled phenomenon of cation migration has been cited as being a mere consequence of that process with no essential ramification to hysteresis. Such works, however, have only shown correlations and not causation. Specifically, studies that clearly preclude the complete absence of either anion redox or cation migration (down to defect-level concentrations) are not reported yet. Herein, we present first principles calculations and experimental data on a bespoke Li-rich system that is indubitably immune to oxygen activity but yet exhibits significant energy inefficiency. Additionally, the results directly implicate transition metal migration as the fundamental, sole process responsible for hysteresis in this material. This study is of particular importance to the design and development of new Li-rich materials aimed at eliminating the role of oxygen and enhancing the effective cationic redox contribution to the capacity and points out the essential need to develop materials devoid of transition metal migration to interstitial sites in both layered and disordered oxides alike.

25 ENERGY STORAGE↗
DOE OSTI2020

Photoinduced charge transfer in Zn(II) and Au(III)-ligated symmetric and asymmetric bacteriochlorin dyads: A computational study

The excited-state properties and photoinduced charge-transfer (CT) kinetics in a series of symmetrical and asymmetrical Zn- and Au-ligated meso–meso-connected bacteriochlorin (BChl) complexes are studied computationally. BChl derivatives, which are excellent near-IR absorbing chromophores, are found to play a central role in bacterial photosynthetic reaction centers but are rarely used in artificial solar energy harvesting systems. The optical properties of chemically linked BChl complexes can be tuned by varying the linking group and involving different ligated metal ions. We investigate charge transfer in BChl dyads that are either directly linked or through a phenylene ring (1,4- phenylene) and which are ligating Zn or Au ions. The directly linked dyads with a nearly perpendicular arrangement of the BChl units bear markedly different properties than phenylene linked dyads. In addition, we find that the dielectric dependence of the intramolecular CT rate is very strong in neutral Zn-ligated dyads, whereas cationic Au-ligated dyads show negligible dielectric dependence of the CT rate. Rate constants of the photo induced CT process are calculated at the semiclassical Marcus level and are compared to fully quantum mechanical Fermi’s golden rule based values. The rates are calculated using a screened range separated hybrid functional that offers a consistent framework for addressing environment polarization. We study solvated systems in two solvents of a low and a high scalar dielectric constant.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Salt supplementation-induced metabolic reprogramming in Streptomyces coelicolor

Members of the genus Streptomyces are major producers of a wide variety of secondary metabolites that serve as bioactive compounds. Many secondary metabolites are produced in response to environmental signals such as biotic and abiotic stresses. In this study, we identified salt supplementation as one of the stimuli activating secondary metabolism in the model Streptomyces species, Streptomyces coelicolor. Comparative metabolomics revealed overproduction of several known secondary metabolites, most notably undecylprodigiosin and coelimycin P1, in addition to their biosynthetic intermediates and derivatives, as well as many unknown metabolites. Transcriptomic analysis revealed activation of diverse biological processes including cation uptake, compatible solute production, and the phosphate limitation stress response through conserved and species-specific mechanisms, presumably to overcome the increased salinity. This response leads to activation of a variety of regulatory and metabolic pathways required for production of secondary metabolites including activation of conserved metabolic pathways for energy and substrate supply and species-specific secondary metabolite biosynthetic gene clusters. Furthermore, several promoter sequences contributing to upregulation of secondary metabolism induced by salt supplementation were identified. Overall, our data show how S. coelicolor copes with the increased salinity and tailors the cellular metabolism toward secondary metabolism in a conserved and species-specific manner.

Otani, Hiroshi [USDOE Joint Genome Institute (JGI)↗
DOE OSTI2026

Influence of solvents on electrochemical stability window of ionic liquid solutions

The electrochemical stability window (ESW) defines the voltage range within which an electrolyte remains stable against oxidation and reduction, serving as a key descriptor for ionic liquid (IL)-based systems. The ESWs of 15 ILs with diverse cation-anion combinations were systematically investigated, both in their neat forms and as binary mixtures with three representative solvents, i.e., propylene carbonate (PC), ethylene glycol (EG), and tetrahydrofuran (THF). Cyclic voltammetry on a glassy carbon electrode determined anodic and cathodic stability limits, revealing that ESW protection in IL-solvent mixtures strongly depends on solvent polarity, proticity, and IL compatibility. PC, with a high dielectric constant and aprotic character, broadened anodic limits and moderately stabilized cathodic limits. THF maintained compact interfacial structure, offering additional cathodic protection, whereas EG, being protic, reduced ESWs via proton-coupled electron transfer and hydrogen evolution. The solvent protection trend followed by PC > THF > EG, with bulky, hydrophobic cations ([HMIM] + , [BMPYRR] + ) and weakly coordinating anions ([NTF 2 ] - , [DCA] - , [DEP] - ) showing the highest ESW protection for 50 mol% IL in these solvents. Among the neat ILs, [EMIM][DEP], [HMIM][PF 6 ], and [BMPYRR][DCA] showed wide ESWs of ∼5.5 V. These results provide valuable insight into solvent-modulated electrochemical stability, enabling rational design of IL-based electrolytes for energy storage and electrosynthesis.

25 ENERGY STORAGE↗
DOE OSTI2021

Strategies for control and mitigation of efflorescence in metakaolin-based geopolymers

Efflorescence can be harmful to material performance as a consequence of microstructural changes due to leaching and carbonation of alkalis. This article identifies mechanisms of efflorescence in metakaolin-based geopolymers, and approaches to reduce free/mobile alkali cations and pore network connectivity, and hence reduce efflorescence. Mechanical, mass transport and microstructural properties are assessed in metakaolin-based geopolymer cements produced using different alkali concentrations in the alkali activator and substitution/addition of blast furnace slag, silica fume, calcium aluminate cement, silicone oil and a dispersive admixture. The most effective strategy to reduce efflorescence results from increasing Si/Al in the geopolymer gel by addition of soluble silicate, silica fume or silicone oil. Addition of calcium aluminate cement or a dispersive admixture also reduce efflorescence, but are less effective. These results confirm that efflorescence may be reduced by controlling the amount of soluble silicates and reducing free alkali cations in geopolymers, providing enhanced performance and durability.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Degradation of Anion Exchange Membranes by Cation Elimination: Impact on Water Uptake, Nanostructure, and Ionic Mobility

Anion exchange membranes (AEMs) are an attractive platform for fuel cell and electrolysis technologies since they enable the use of cheaper, nonplatinum group metal electrodes and components. However, the widespread adoption of AEM-based devices is limited by chemical degradation of the AEM in the highly alkaline medium of operation. Experimental studies report three major pathways of degradation, including substitution (S N 2), elimination (E2), and backbone cleavage. The decline in membrane performance is likely due to a cumulative effect of several pathways, which has proven to be difficult to disentangle through experiments. Here we use coarse-grained molecular simulations to isolate the impact of E2 degradation, where cationic sites are replaced by an alkene group, on AEM water uptake, nanoscale morphology, structure of the ion-conducting channels, water mobility, and ionic conductivity. Our studies focus on the well-studied model AEM polyphenylene oxide with tetraalkylammonium cationic sites (PPO-TMA). We find that about half of the hydrophobic groups resulting from the degradation retract into the hydrophobic domains of the membrane. The reduction in ion exchange capacity (IEC) and the hydrophobicity of the alkene groups decrease both the equilibrium water uptake (%WU) and the number of water molecules per cation (λ) of the membrane. Interestingly, the evolution of λ with the IEC seems to follow that of undegraded PPO-TMA membranes. Additionally, we ascribe this to the similarity between the structure of the degraded monomer and the neutral one in the polymer. We conclude that most of the performance losses originate in the lower hydration of the degraded membrane.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Importance of interface open circuit potential on aqueous hydrogenolytic reduction of benzyl alcohol over Pd/C

Abstract The open circuit potential (OCP) established by the quasi-equilibrated electrode reaction of H 2 and H 3 O + (hydr.) , complicates catalytic reactions significantly. The hydrogenolysis rate of benzylic alcohol on Pd/C increases 2-3 orders of magnitude with the pH decreasing from 7 to 0.6. The reaction follows a pathway of protonated benzyl alcohol dehydration to a benzylic carbenium ion, followed by a hydride addition to form toluene. The dehydration of protonated benzyl alcohol is kinetic relevent, thus, being enhanced at lower pH. The OCP stabilizes all cationic species in the elementary steps. Particularly, the initial state (benzyl alcohol oxonium ion) is less stabilized than the dehydration transition state and the product (benzylic carbenium), thus, lowering the free energy barrier of the rate-determining step. In accordance, the rate increased with increasingly negative OCP. Beside OCP, an external negative electric potential in an electrocatlaytic system was also demonstrated to enhance the rate in the same way.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗