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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 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Potassium Metal Batteries: Stable Potassium Metal Anodes with an All-Aluminum Current Collector through Improved Electrolyte Wetting (Adv. Mater. 49/2020)

An explorer is kayaking in uncharted territory, representing the exciting scientific pursuit of emerging metal batteries (MBs). Water is flowing smoothly over the jagged rocks, representing dendrite-free metal anodes as well as enhanced electrolyte wetting, both due to geometrical roughness. The electric eels underneath represent potassium-based energy storage, as they utilize potassium and sodium ions for electricity. In article number 2002908, Pengcheng Liu, David Mitlin, and co-workers present a route via improved electrolyte wetting toward stable potassium metal batteries with an all-aluminum current collector.

25 ENERGY STORAGE↗
DOE OSTI2021

Design of a Stable Heusler Alloy with Switchable Metal-to-Half-Metal Transition at Finite Temperature

We report the electronic structure and metallicity of Si-doped Mn2VGe Heusler alloys within the first-principles density-functional theory framework are discussed. Mn2VGe is found to assume two stable structures at (cubic) lattice constants of 5.7 and 6.05 Å, which are well-separated in energy and correspond to half-metallic (low-spin) and metallic (high-spin) phases, respectively. Substitution of Ge by Si reduces the energy difference between these two phases, which become nearly degenerate at an Si concentration of ≈3.125 at% at zero temperature. The analysis shows that the switching between the high- and low-spin phases for this composition can be triggered via a pressure of 2.8 GPa at 300 K. Si-doped Mn 2 VGe can thus provide an ultrafast, low power, cost-effective materials platform for spintronics applications.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Hybrid Lithium-Sulfur Batteries with an Advanced Gel Cathode and Stabilized Lithium-Metal Anode

The insulating nature of sulfur, polysulfide shuttle effect, and lithium metal deterioration cause a decrease in practical energy density and fast capacity fade in lithium-sulfur batteries. Here, we present an integrated strategy for the development of hybrid Li-S batteries based on a gel sulfur cathode, a solid electrolyte, and a protective anolyte composed of highly-concentrated salt electrolyte containing mixed additives. The dense solid electrolyte completely blocks polysulfide diffusion, and also makes it possible to investigate the cathode and anode independently. This gel cathode effectively traps the polysulfide active material while maintaining a low electrolyte to sulfur ratio (E/S) of 5.2 mL/g. The anolyte effectively protects the Li metal and suppresses the consumption of liquid electrolyte, enabling stable long-term cycling for over 700 hours in Li symmetric cells. This advanced design can simultaneously suppress the polysulfide shuttle, protect Li metal, and reduce the liquid electrolyte usage. The assembled hybrid batteries exhibit remarkably stable cycling performance over 300 cycles with high capacity. Finally, surface-sensitive techniques were carried out to directly visualize and to probe the interphase formed on the surface of the LAGP pellet, which may help stabilize the solid-liquid interface.

25 ENERGY STORAGE↗
DOE OSTI2019

An Americium-Containing Metal-Organic Framework: A Platform for Studying Transplutonium Elements

The synthesis, structural and spectroscopic characterization of the first transplutonium metal-organic framework (MOF) is described. The preparation and structure of Am GWMOF-6, [Am2(C6H8O4)3(H2O)2][(C10H8N2)], is analogous to that of the isostructural trivalent lanthanide-only containing material GWMOF-6. The presented MOF architecture is used as a plat-form to probe Am3+ coordination chemistry and guest-enhanced luminescent emission, whereas the framework itself provided a means to monitor the effects of self-irradiation upon crystallinity over time. Presented here is a discussion of these properties and the opportunities that metal-organic frameworks provide in the structural and spectroscopic study of actinides.

Ridenour, James A.↗
DOE OSTI2015

A Metal-Organic Framework Containing Unusual Eight-Connected Zr–-Oxo Secondary Building Units and Orthogonal Carboxylic Acids for Ultra-sensitive Metal Detection

Two metal-organic frameworks (MOFs) with Zr-oxo secondary building units (SBUs) were prepared by using p,p'-terphenyldicarboxylate (TPDC) bridging ligands pre-functionalized with orthogonal succinic acid (MOF-1) and maleic acid groups (MOF-2). Single-crystal X-ray structure analysis of MOF-1 provides the first direct evidence for eight-connected SBUs in UiO-type MOFs. In contrast, MOF-2 contains twelve-connected SBUs as seen in the traditional UiO MOF topology. These structural assignments were confirmed by extended X-ray absorption fine structure (EXAFS) analysis. The highly porous MOF-1 is an excellent fluorescence sensor for metal ions with the detection limit of <0.5 ppb for Mn 2+ and three to four orders of magnitude greater sensitivity for metal ions than previously reported luminescent MOFs.

Carboni, Michaël↗
DOE OSTI2013

The use of tetragnathid spiders as bioindicators of metal exposure at a coal ASH spill site

Abstract On 22 December 2008, a dike containing coal fly ash from the Tennessee Valley Authority Kingston Fossil Fuel Plant (TN, USA) failed, resulting in the largest coal ash spill in US history. The present study was designed to determine sediment metal concentrations at multiple site locations and to determine whether site-specific bioaccumulation of metals existed in tetragnathid spiders. Selenium and nickel were the only 2 metals to exceed the US Environmental Protection Agency sediment screening levels. Selenium concentrations in spiders were significantly higher at ash-affected sites than in those from reference sites. The ratio of methylmercury to total mercury in spiders was found to be similar to that in other organisms (65–75%), which highlights the potential use of tetragnathid spiders as an indicator species for tracing contaminant transfer between the aquatic and terrestrial ecosystems. Environ Toxicol Chem 2013;32:2065–2068. © 2013 SETAC

Otter, Ryan R.↗
DOE OSTI2014

Correlating the degree of metal–promoter interaction to ethanol selectivity over MnRh/CNTs CO hydrogenation catalysts

Multi-walled carbon nanotubes (MCNTs) were used as a support for Rh-based catalysts for high pressure (20 bar) CO hydrogenation. 3 wt% Rh/CNTs catalysts were loaded with 1 wt% and 2 wt% Mn promoter, respectively, in order to study the effect of metal–promoter interactions for ethanol synthesis. Both STEM and EXAFS results showed ≈1 nm Rh particles in promoted as well as the unpromoted catalysts, STEM and EELS results verified the enhanced metal–promoter interaction when the amount of Mn promoter increased from 1 wt% to 2 wt%. The enhancement in the degree of metal–promoter interaction leads to an increase in the ethanol selectivity. Moreover, due to the nature of CNTs (low Z number), the Mn–Rh interactions could be observed at atomic resolution during the STEM–EELS characterization, and the promoter phase is confirmed as Mn(II) oxide by XANES and EELS.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Critical Parameters for Evaluating Coin Cells and Pouch Cells of Rechargeable Li-Metal Batteries

Lithium ion and lithium metal batteries have received tremendous interest in the last decade for a wide range of energy storage applications. Although great progress has been made in developing new electrode materials and concepts, it is difficult to rapidly incorporate these advances in battery technologies. A key challenge is the knowledge gap between the fundamental materials research and the cell-level understanding of the relationship between high energy and stable cycling. As a result, the literature reports are based on a wide range of experimental conditions that cannot be easily realized in realistic cells. Taking lithium metal batteries as an example, this paper briefly discusses the fundamental mechanisms that lead to the inconsistent observations in battery research. We then propose development of a standard testing protocol based on the requirements of high-energy lithium metal cells. The importance of building a standard testing protocol is emphasized to accelerate the discovery of solutions for real challenges as well as inspire innovations that are readily adaptable to real batteries.

Chen, Shuru↗
DOE OSTI2015

Thermodynamics of metal-organic frameworks

Although there have been extensive studies over the past decade in the synthesis and application of metal-organic frameworks (MOFs), investigation of their thermodynamic stability and of the energetics of guest–host interactions has been much more limited. This review summarizes recent progress in experimental (calorimetric) determination of the thermodynamics of MOF materials. The enthalpies of MOFs relative to dense phase assemblages suggest only modest metastability, with a general increase of enthalpy with increasing molar volume, which becomes less pronounced at higher porosity. The energy landscape of nanoporous materials (inorganic and hybrid) consists of a pair of parallel patterns within a fairly narrow range of metastability of 5–30 kJ per mole of tetrahedra in zeolites and mesoporous silicas or per mole of metal in MOFs. Thus strong thermodynamic instability does not seem to limit framework formation. There are strong interactions within the chemisorption range for small molecule–MOF interactions with defined chemical binding at the metal centers or other specific locations. Coexistence of surface binding and confinement can lead to much stronger guest–host interactions. - Graphical abstract: Energy landscape of inorganic and hybrid porous materials. - Highlights: • Thermochemical data on various MOF structures were experimentally determined. • MOFs are moderately unstable relative to their dense phase assemblage. • Overall energetic landscape of porous materials was revealed. • Guest–host interactions in MOFs were evaluated directly using calorimetry. • Confinement effect and defined chemical binding lead to strong interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Two new supramolecular metal diphosphonates: Synthesis, characterization, crystal structure and inhibiting effects on metallic corrosion

Two new divalent metal(II) aminodiphosphonates with layered structure, namely, Cu(H{sub 3}L{sup 1}){sub 2}·2H{sub 2}O (1), [H4L{sup 1}=methyl-N(CH{sub 2}PO{sub 3}H{sub 2}){sub 2}] and Cd{sub 2}(H{sub 2}L{sup 2}){sub 4}(2), [H{sub 4}L{sup 2}=n-propyl-N(CH{sub 2}PO{sub 3}H{sub 2}){sub 2}] were synthesized and characterized. The Cu(II) ions in complex 1 are octahedrally coordinated by four oxygen atoms from two chelating ligands and two phosphonate oxygen atoms from two neighboring Cu(H{sub 3}L{sup 1}){sub 2} units. The Cu(H{sub 3}L{sup 1}){sub 2} units are interconnected by bridging phosphonate groups, forming a 2-D metal phosphonate layer. The structure of complex 2 contains two unique Cd(II) ions octahedrally-coordinated by six phosphonate oxygen atoms from four H{sub 2}L{sup 2} diphosphonate anions. Corrosion inhibition performances of 1 and 2 were also compared with each other in order to study the effect of combinations of externally added Cd/H{sub 4}L{sup 2} and Cu/H{sub 4}L{sup 1} (1:1 ratio) on corrosion rates of carbon steel. It was found that at pH 3.0, Cd/H{sub 4}L{sup 2} or Cu/H{sub 4}L{sup 1} combinations do not have noticeable corrosion inhibition efficiency for carbon steel. In contrast, at pH 7.0, higher corrosion inhibition efficiency was achieved for Cd/H{sub 4}L{sup 2}. Physical characterizations such as scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were applied to study the corrosion specimens and film material. - Graphical abstract: Two new metal phosphonates have been synthesized and characterized by single-crystal X-ray diffraction and thermogravimetric analysis. corrosion inhibition performances 1 and 2 are also compared.

36 MATERIALS SCIENCE↗
DOE OSTI2026

An Experimental and Numerical Study of Plasma Treatment Effects on Adhesive Joints of Metals, CFRTPs, and Metal–CFRTP Combinations

This work investigates the effects of plasma surface treatment on both the local adherend–adhesive interfacial strength and the global lap shear strength (LSS) of adhesively-bonded joints composed of metals, CFRTPs, and metal-CFRTP combinations, using AA6061 and CFRPPA as representative examples. Experimental and computational results show that plasma treatment improved the ratio of CFRPPA–adhesive interfacial normal strength to adhesive tensile strength (sint,n/scri,t,adhesive) from 0.59–1.00 to 0.91–1.73, leading to an average 90% increase in LSS for CFRPPA-related joints. In contrast, the LSS and sint,n/scri,t,adhesive values of AA6061–AA6061 joints (>=2.27) remained nearly unchanged after plasma treatment. The enhanced joint bonding was further supported by post-failure surface morphologies from three-dimensional profilometry and simulations, showing a transition from dominant interfacial failure to mixed modes involving interfacial, cohesive, and slight fiber-peeling failures. The LSS evolution with respect to sint,n/scri,t,adhesive was numerically established until the saturation of the LSS of various joints, and the behavior of AA6061–CFRPPA T-joints with varying interfacial strengths was also modeled. This study highlights the importance of local interfacial bonding strength, rather than global LSS, for understanding and optimizing the mechanical performance of adhesively-bonded composite–metal and composite-composite structures via different surface modification strategies.

Qiao, Yao (ORCID:0000000265867604)↗
DOE OSTI2025

Ligand Hole Driven Metal–Insulator Transition Exemplified in a Layered Transition Metal Oxide

The interplay of cooperative Jahn–Teller (JT) distortions and charge-disproportionation (CD) with a strong electronic correlation in transition metal oxides leads to structural symmetry breaking. Both JT and CD often manifest in the form of significant modifications in electronic and structural properties such as band splitting, metal–insulator transitions (MIT), and enhanced electron lattice interactions. Notably, the charge-disproportionation is a key electronic feature that drives the MIT. Here, we demonstrate and quantify it using first-principles calculations combining density-functional theory, dynamical mean-field theory, and spin–lattice Monte Carlo simulations. Taking Ca 2 FeMnO 6 as a prototypical example of a correlated oxide, our ab initio study shows that MIT in Ca 2 FeMnO 6 arises from the partial localization of oxygen ligand holes at alternate Fe sites that control both charge and magnetic ordering. Interestingly, the band gap was found to be fundamentally controlled by the strength of the charge-transfer energy and not by the Mott–Hubbard interactions. The novel physics and insights presented in this work reveal promising routes for tuning the electronic functionality in transition-metal oxides.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Metallaphotoredox: The Merger of Photoredox and Transition Metal Catalysis

The merger of photoredox catalysis with transition metal catalysis, termed metallaphotoredox catalysis, has become a mainstay in synthetic methodology over the past decade. Metallaphotoredox catalysis has combined the unparalleled capacity of transition metal catalysis for bond formation with the broad utility of photoinduced electron- and energy-transfer processes. Photocatalytic substrate activation has allowed the engagement of simple starting materials in metal-mediated bond-forming processes. Moreover, electron or energy transfer directly with key organometallic intermediates has provided novel activation modes entirely complementary to traditional catalytic platforms. Finally, this Review details and contextualizes the advancements in molecule construction brought forth by metallaphotocatalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗