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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Hydrogen Storage with Aluminum Formate, ALF: Experimental, Computational, and Technoeconomic Studies

Long-duration storage of hydrogen is necessary for coupling renewable H 2 with stationary fuel cell power applications. In this work, aluminum formate (ALF), which adopts the ReO 3 -type structure, is shown to have remarkable H 2 storage performance at non-cryogenic (>120 K) temperatures and low pressures. The most promising performance of ALF is found between 120 K and 160 K and at 10 bar to 20 bar. The study illustrates H 2 adsorption performance of ALF over the 77 K to 296 K temperature range using gas isotherms, in situ neutron powder diffraction, and DFT calculations, as well as technoeconomic analysis (TEA), illustrating ALF’s competitive performance for long-duration storage versus compressed hydrogen and leading metal–organic frameworks. In the TEA, it is shown that ALF’s storage capacity, when combined with a temperature/pressure swing process, has advantages versus compressed H 2 at a fraction of the pressure (15 bar versus 350 bar). In conclusion, given ALF’s performance in the 10 bar to 20 bar regime under moderate cooling, it is particularly promising for use in safe storage systems serving fuel cells.

08 HYDROGEN↗
DOE OSTI2025

Hydrogen Storage with Aluminum Formate, ALF: Experimental, Computational, and Technoeconomic Studies

Long-duration storage of hydrogen is necessary for coupling renewable H2 with stationary fuel cell power applications. In this presentation, I will discuss how aluminum formate, Al(HCOO)3 (ALF), which adopts an ReO3-type structure, is shown to have remarkable H2 storage performance at non-cryogenic (> 120 K) temperatures and low pressures. The most promising performance of ALF is found between 120 K and 160 K and at 10 bar to 20 bar. The talk will cover and illustrate the H2 adsorption performance of ALF over the 77 K to 296 K temperature range using gas isotherms, in situ neutron powder diffraction, and DFT calculations, as well as technoeconomic analysis (TEA), illustrating ALF’s competitive performance for long-duration storage versus compressed hydrogen and leading metal–organic frameworks. In the TEA, it is shown that ALF’s storage capacity, when combined with a temperature/pressure swing process, has advantages versus compressed H2 at a fraction of the pressure (15 bar versus 350 bar). Given ALF’s performance in the 10 bar to 20 bar regime under moderate cooling, it is particularly promising for use in safe storage systems serving fuel cells, and is currently the only MOF that works in this moderate temperature range/ low pressure regime to be cost competitive with compressed H2 gas for large scale H2 storage.[1]

Chemistry↗
DOE OSTI2021

Comparison of AlF 3 thin films grown by thermal and plasma enhanced atomic layer deposition

Films of aluminum fluoride (AlF 3 ) deposited by thermal and plasma enhanced atomic layer deposition (PEALD) have been compared using in situ multiwavelength ellipsometry (MWE) and monochromatic x-ray photoelectron spectroscopy (XPS). The AlF 3 films were grown using cyclic exposures of trimethylaluminum, hydrogen fluoride, and H radicals from a remote H 2 inductively coupled plasma. Films were characterized in situ using MWE and XPS for growth rate, film composition, and impurity incorporation. The MWE showed a growth rate of 1.1 and 0.7 Å per cycle, at 100 °C, for thermal and plasma enhanced ALD AlF 3 films, respectively. Carbon incorporation was below the XPS detection limit. The plasma enhanced ALD AlF 3 film showed the presence of Al-Al chemical states, in the Al 2p scans, suggesting the presence of Al-rich clusters with a concentration of 14%. The Al-rich clusters are thought to originate during the hydrogen plasma step of the PEALD process. Finally, the Al-rich clusters were not detected in thermal ALD AlF 3 films using the same precursors and substrate temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Borderline first-order magnetic phase transition in AlFe 2 B 2

The thermal evolution of lattice parameters coupled with heat capacity data provide insight into tailorable magnetism-structure attributes in the orthorhombic compound AlFe 2 B 2 that was synthesized with and without small additions of gallium. Temperature-dependent X-ray powder diffraction experiments conducted through the magnetic phase transition reveal that the a- and b-parameters of both samples increase with increasing temperature while the c-parameter decreases. While a weak volumetric thermal expansion is noted over a range of temperatures well below and above the magnetic phase transition, anomalous behavior was observed within the phase transition region itself to reveal a magnetostructural phase transition with borderline first-order character in the Ga-modified sample but of more second-order character in the Ga-free sample. It is established that the nearest-neighbor Fe-Fe interatomic distance within the (ab)-plane plays a dominant role in influencing the magneto-functional response of these compounds. The magnetocaloric properties are discussed in the context of temperature-induced changes of the interatomic bonding that are influenced by the hypothesized presence of iron antisite defects in the AlFe 2 B 2 lattice.

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

Materials Data on AlFe by Materials Project

FeAl is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Fe is bonded in a body-centered cubic geometry to eight equivalent Al atoms. All Fe–Al bond lengths are 2.49 Å. Al is bonded in a body-centered cubic geometry to eight equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlFe by Materials Project

FeAl crystallizes in the hexagonal P6/mmm space group. The structure is one-dimensional and consists of one FeAl ribbon oriented in the (0, 0, 1) direction. Fe is bonded in a distorted linear geometry to two equivalent Al atoms. Both Fe–Al bond lengths are 2.45 Å. Al is bonded in a distorted linear geometry to two equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(AlFe)6 by Materials Project

Sc(FeAl)6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Sc is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.20 Å) and eight longer (3.25 Å) Sc–Fe bond lengths. There are a spread of Sc–Al bond distances ranging from 2.80–2.94 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Sc, four Fe, and six Al atoms. There are two shorter (2.47 Å) and two longer (2.48 Å) Fe–Fe bond lengths. There are two shorter (2.51 Å) and four longer (2.57 Å) Fe–Al bond lengths. In the second Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Sc, four equivalent Fe, and six Al atoms. There are four shorter (2.56 Å) and two longer (2.59 Å) Fe–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Sc, six Fe, and three Al atoms. There are one shorter (2.69 Å) and two longer (2.83 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Sc, six Fe, and one Al atom. The Al–Al bond length is 2.83 Å. In the third Al site, Al is bonded in a 6-coordinate geometry to two equivalent Sc, six Fe, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf(AlFe)6 by Materials Project

Fe6Al6Hf crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Hf is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.19 Å) and eight longer (3.24 Å) Hf–Fe bond lengths. There are two shorter (2.82 Å) and six longer (2.93 Å) Hf–Al bond lengths. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Hf, four Fe, and six Al atoms. There are two shorter (2.47 Å) and two longer (2.48 Å) Fe–Fe bond lengths. There are two shorter (2.50 Å) and four longer (2.57 Å) Fe–Al bond lengths. In the second Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Hf, four equivalent Fe, and six Al atoms. There are a spread of Fe–Al bond distances ranging from 2.55–2.60 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Hf, six Fe, and three Al atoms. There are one shorter (2.67 Å) and two longer (2.83 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Hf, six Fe, and one Al atom. The Al–Al bond length is 2.78 Å. In the third Al site, Al is bonded in a 6-coordinate geometry to two equivalent Hf, six Fe, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(AlFe)6 by Materials Project

HoFe6Al6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.21 Å) and eight longer (3.28 Å) Ho–Fe bond lengths. There are a spread of Ho–Al bond distances ranging from 2.85–3.01 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Ho, four Fe, and six Al atoms. All Fe–Fe bond lengths are 2.50 Å. There are two shorter (2.51 Å) and four longer (2.60 Å) Fe–Al bond lengths. In the second Fe site, Fe is bonded to two equivalent Ho, four equivalent Fe, and six Al atoms to form a mixture of distorted face, edge, and corner-sharing FeHo2Al6Fe4 cuboctahedra. There are two shorter (2.59 Å) and four longer (2.63 Å) Fe–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Ho, six Fe, and three Al atoms. There are one shorter (2.65 Å) and two longer (2.83 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Ho, six Fe, and one Al atom. The Al–Al bond length is 2.78 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Ho, six Fe, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(AlFe)6 by Materials Project

ErFe6Al6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Er is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.22 Å) and eight longer (3.27 Å) Er–Fe bond lengths. There are a spread of Er–Al bond distances ranging from 2.85–2.99 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Er, four Fe, and six Al atoms. All Fe–Fe bond lengths are 2.49 Å. There are two shorter (2.51 Å) and four longer (2.59 Å) Fe–Al bond lengths. In the second Fe site, Fe is bonded to two equivalent Er, four equivalent Fe, and six Al atoms to form a mixture of distorted corner, edge, and face-sharing FeEr2Al6Fe4 cuboctahedra. There are two shorter (2.58 Å) and four longer (2.62 Å) Fe–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Er, six Fe, and three Al atoms. There are one shorter (2.66 Å) and two longer (2.82 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Er, six Fe, and one Al atom. The Al–Al bond length is 2.78 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Er, six Fe, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tb(AlFe)6 by Materials Project

TbFe6Al6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Tb is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.23 Å) and eight longer (3.28 Å) Tb–Fe bond lengths. There are a spread of Tb–Al bond distances ranging from 2.87–3.01 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to two equivalent Tb, four Fe, and six Al atoms to form a mixture of distorted face, edge, and corner-sharing FeTb2Al6Fe4 cuboctahedra. There are two shorter (2.49 Å) and two longer (2.50 Å) Fe–Fe bond lengths. There are two shorter (2.52 Å) and four longer (2.60 Å) Fe–Al bond lengths. In the second Fe site, Fe is bonded to two equivalent Tb, four equivalent Fe, and six Al atoms to form a mixture of distorted face, edge, and corner-sharing FeTb2Al6Fe4 cuboctahedra. There are a spread of Fe–Al bond distances ranging from 2.58–2.64 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Tb, six Fe, and three Al atoms. There are one shorter (2.66 Å) and two longer (2.82 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Tb and six Fe atoms. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Tb, six Fe, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(AlFe)6 by Materials Project

UFe6Al6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.16 Å) and eight longer (3.28 Å) U–Fe bond lengths. There are a spread of U–Al bond distances ranging from 2.91–3.02 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent U, four Fe, and six Al atoms. There are two shorter (2.47 Å) and two longer (2.50 Å) Fe–Fe bond lengths. There are two shorter (2.50 Å) and four longer (2.61 Å) Fe–Al bond lengths. In the second Fe site, Fe is bonded to two equivalent U, four equivalent Fe, and six Al atoms to form a mixture of distorted corner, edge, and face-sharing FeU2Al6Fe4 cuboctahedra. There are two shorter (2.62 Å) and four longer (2.64 Å) Fe–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one U, six Fe, and three Al atoms. There are one shorter (2.62 Å) and two longer (2.79 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one U, six Fe, and three Al atoms. There are one shorter (2.69 Å) and two longer (2.93 Å) Al–Al bond lengths. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent U, six Fe, and four Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(AlFe)6 by Materials Project

Pr(FeAl)6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.26 Å) and eight longer (3.32 Å) Pr–Fe bond lengths. There are a spread of Pr–Al bond distances ranging from 2.93–3.07 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to two equivalent Pr, four Fe, and six Al atoms to form a mixture of distorted face, edge, and corner-sharing FePr2Al6Fe4 cuboctahedra. There are two shorter (2.51 Å) and two longer (2.52 Å) Fe–Fe bond lengths. There are a spread of Fe–Al bond distances ranging from 2.53–2.64 Å. In the second Fe site, Fe is bonded to two equivalent Pr, four equivalent Fe, and six Al atoms to form a mixture of distorted face, edge, and corner-sharing FePr2Al6Fe4 cuboctahedra. There are a spread of Fe–Al bond distances ranging from 2.60–2.73 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Pr, six Fe, and three Al atoms. There are one shorter (2.65 Å) and two longer (2.82 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 7-coordinate geometry to one Pr, six Fe, and two equivalent Al atoms. Both Al–Al bond lengths are 2.96 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Pr, six Fe, and four Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Multifunctional Separator Allows Stable Cycling of Potassium Metal Anodes and of Potassium Metal Batteries

Here, this is the first report of a multifunctional separator for potassium-metal batteries (KMBs). Here, double-coated tape-cast microscale AlF 3 on polypropylene (AlF 3 @PP) yields state-of-the-art electrochemical performance: symmetric cells are stable after 1000 cycles (2000 h) at 0.5 mA cm –2 and 0.5 mAh cm –2 , with 0.042 V overpotential. Stability is maintained at 5.0 mA cm –2 for 600 cycles (240 h), with 0.138 V overpotential. Postcycled plated surface is dendrite-free, while stripped surface contains smooth solid electrolyte interphase (SEI). Conventional PP cells fail rapidly, with dendrites at plating, and “dead metal” and SEI clumps at stripping. Potassium hexacyanoferrate(III) cathode KMBs with AlF 3 @PP display enhanced capacity retention (91% at 100 cycles vs 58%). AlF 3 partially reacts with K to form an artificial SEI containing KF, AlF 3 , and Al 2 O 3 phases. The AlF 3 @PP promotes complete electrolyte wetting and enhances uptake, improves ion conductivity, and increases ion transference number. The higher of K + transference number is ascribed to the strong interaction between AlF 3 and FSI – anions, as revealed through 19 F NMR. The enhancement in wetting and performance is general, being demonstrated with ester- and ether-based solvents, with K-, Na-, or Li- salts, and with different commercial separators. In full batteries, AlF 3 prevents Fe crossover and cycling-induced cathode pulverization.

NMB↗
DOE OSTI2021

Stabilized Lithium, Manganese-Rich Layered Cathode Materials Enabled by Integrating Co-Doping and Nanocoating

While lithium, manganese-rich (LMR) layered oxide cathode materials offer high energy density (>900 Wh kg –1 ) and low cost, LMR is susceptible to continuous capacity and voltage decay from the oxygen migration and side reaction with aqueous electrolyte at high voltage. Herein, the integration of Na/F co-doping (CD) and AlF 3 coating on LMR is achieved without the need of complex atomic layer deposition. Akin to pristine and CD samples, CD with 1 wt % AlF 3 (CD-1.0 wt %) shows excellent electrochemical performance with the capacity and voltage retentions of 93 and 91% after 150 cycles at 0.5C, respectively, and increased ionic conductivity. Spectroscopic analysis indicates that the coating mainly influences the Co distribution, where Co is enriched on the surface, and partial diffusion of Al 3+ ions toward the bulk, leading to a slight change of transition-metal (TM) valence states at the nanometer scale and the formation of a stable Li x (CoAl)O y phase. Post-cycling analysis reveals that CD-1.0 wt % can alleviate the formation of rock-salt structure and Mn dissolution. Besides, little to no metal segregation is detected for the cycled CD-1.0 wt % sample. This finding presents the first instance to apply co-doping and AlF 3 coating as a new strategy to enhance the structural homogeneity and takes another step toward their commercial viability.

25 ENERGY STORAGE↗