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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Flexible 2D Boron Imidazolate Framework for Polysulfide Adsorption in Lithium–Sulfur Batteries

We report the "polysulfide shuttle," a process initiated by the dissolution of polysulfides, is recognized to be one of the major failure mechanisms of lithium-sulfur (Li-S) batteries. Much research effort has been dedicated toward efficient cathode additives and host materials to suppress the leaching of polysulfide species. Herein, we report a new 2D metal-organic framework constituted by a tritopic ligand, boron imidazolate ([BH(Im) 3 ] - , Im = imidazole), and Co 2+ ions for lithium polysulfide adsorption. The cobalt imidazolate framework (CoN 6 -BIF) contains octahedrally coordinated Co centers that form two-dimensional layers in the a,b plane. Composite cathodes containing CoN 6 -BIF exhibited high sulfur utilization and capacity retention, resulting in improved specific capacity and cycle life compared to sulfur/carbon controls. Density functional theory (DFT) calculations suggest that CoN 6 -BIF linkers are rotationally flexible, allowing the framework to accommodate polysulfide in the expanded pores. This unusual property of BIFs opens up new avenues for exploring flexible metal-organic frameworks (MOFs) and their applications to energy storage.

25 ENERGY STORAGE↗
DOE OSTI2020

Materials Data on HgB(CN)4 by Materials Project

BHg(CN)3CN crystallizes in the orthorhombic Pbcm space group. The structure is zero-dimensional and consists of eight boron molecules, eight hydrogen cyanide molecules, and eight Hg(CN)3 clusters. In each Hg(CN)3 cluster, Hg1+ is bonded in a 4-coordinate geometry to three N3- atoms. There are one shorter (2.39 Å) and two longer (2.40 Å) Hg–N bond lengths. There are two inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.16 Å. In the second C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.16 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a linear geometry to one Hg1+ and one C2+ atom. In the second N3- site, N3- is bonded in a distorted bent 150 degrees geometry to one Hg1+ and one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrSbPt by Materials Project

PtCrSb is alpha boron-derived structured and crystallizes in the cubic P2_13 space group. The structure is three-dimensional. Cr3+ is bonded in a 7-coordinate geometry to three equivalent Pt2- and four equivalent Sb1- atoms. All Cr–Pt bond lengths are 2.60 Å. There are three shorter (2.77 Å) and one longer (2.83 Å) Cr–Sb bond lengths. Pt2- is bonded in a hexagonal planar geometry to three equivalent Cr3+ and three equivalent Sb1- atoms. All Pt–Sb bond lengths are 2.75 Å. Sb1- is bonded in a 7-coordinate geometry to four equivalent Cr3+ and three equivalent Pt2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

A Reductively Stable Electrolyte Realizes Deep Cycling Behavior in Anode‐free Sodium Batteries

For anode‐free sodium batteries to achieve practical consideration, highly reversible chemistries require exceptional ≥99.95% coulombic efficiencies that maintain over prolonged cycling periods. To do so, consumption of this severely limited sodium inventory must be restricted while metal nucleation processes that comprise the in situ formed metal anode are improved. Herein, we describe a fluorine‐free carborane electrolyte that satisfies these criteria by emphasizing reductive stability and weakly coordinating anion behavior as design principles. We find this approach promotes the development of a thin, robust SEI chemistry rich in both organic speciation and boron. The electrolyte described herein exhibits ideal metal nucleation behavior on one‐micron thin carbonaceous current collector surfaces and achieves a metal deposition/stripping efficiency near parity for 400 cycles. This novel anode chemistry is introduced to anode‐free full cell configurations where 87% of the initial discharge capacity is retained after 1000 cycles at 2.0 C. In conclusion, post‐test characterization of deep‐cycled anode‐free cells reveals suppressed capacity fade in these systems is attributed to the chemical stability of the carborane anion.

anode-free↗
DOE OSTI2020

Materials Data on CaSi2 by Materials Project

CaSi2 is alpha boron-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ca is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Ca–Si bond distances ranging from 3.01–3.12 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded to three equivalent Ca and three equivalent Si atoms to form distorted edge-sharing SiCa3Si3 octahedra. All Si–Si bond lengths are 2.39 Å. In the second Si site, Si is bonded in a 7-coordinate geometry to four equivalent Ca and three equivalent Si atoms. All Si–Si bond lengths are 2.44 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Rational Design of Superconducting Metal Hydrides via Chemical Pressure Tuning**

Abstract The high critical superconducting temperatures ( T c s) of metal hydride phases with clathrate‐like hydrogen networks have generated great interest. Herein, we employ the Density Functional Theory‐Chemical Pressure (DFT‐CP) method to explain why certain electropositive elements adopt these structure types, whereas others distort the hydrogenic lattice, thereby decreasing the T c . The progressive opening of the H 24 polyhedra in MH 6 phases is shown to arise from internal pressures exerted by large metal atoms, some of which may favor an even higher hydrogen content that loosens the metal atom coordination environments. The stability of the LaH 10 and LaBH 8 phases is tied to stuffing of their shared hydrogen network with either additional hydrogen or boron atoms. The predictive capabilities of DFT‐CP are finally applied to the Y−X−H system to identify possible ternary additions yielding a superconducting phase stable to low pressures.

Hilleke, Katerina P.↗
DOE OSTI2022

Rational Design of Superconducting Metal Hydrides via Chemical Pressure Tuning

The high critical superconducting temperatures (T c s) of metal hydride phases with clathrate-like hydrogen networks have generated great interest. Herein, we employ the Density Functional Theory-Chemical Pressure (DFT-CP) method to explain why certain electropositive elements adopt these structure types, whereas others distort the hydrogenic lattice, thereby decreasing the T c . The progressive opening of the H 24 polyhedra in MH 6 phases is shown to arise from internal pressures exerted by large metal atoms, some of which may favor an even higher hydrogen content that loosens the metal atom coordination environments. The stability of the LaH 10 and LaBH 8 phases is tied to stuffing of their shared hydrogen network with either additional hydrogen or boron atoms. Furthermore, the predictive capabilities of DFT-CP are finally applied to the Y-X-H system to identify possible ternary additions yielding a superconducting phase stable to low pressures.

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

Materials Data on Tl3B by Materials Project

(Tl)3B is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of four boron molecules and one Tl framework. In the Tl framework, there are two inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in a 4-coordinate geometry to four equivalent Tl1+ atoms. All Tl–Tl bond lengths are 3.23 Å. In the second Tl1+ site, Tl1+ is bonded in a body-centered cubic geometry to eight equivalent Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B by Materials Project

B crystallizes in the trigonal R-3m space group. The structure is three-dimensional and consists of three boron molecules and one B framework. In the B framework, there are fourteen inequivalent B sites. In the first B site, B is bonded in a 6-coordinate geometry to six B atoms. There are a spread of B–B bond distances ranging from 1.69–1.83 Å. In the second B site, B is bonded in a 6-coordinate geometry to six B atoms. There are a spread of B–B bond distances ranging from 1.63–1.82 Å. In the third B site, B is bonded in a 8-coordinate geometry to eight B atoms. There are a spread of B–B bond distances ranging from 1.75–1.96 Å. In the fourth B site, B is bonded in a 6-coordinate geometry to six B atoms. There is one shorter (1.71 Å) and two longer (1.78 Å) B–B bond length. In the fifth B site, B is bonded in a 6-coordinate geometry to six B atoms. There are a spread of B–B bond distances ranging from 1.72–1.76 Å. In the sixth B site, B is bonded in a 5-coordinate geometry to five B atoms. There is one shorter (1.70 Å) and one longer (1.96 Å) B–B bond length. In the seventh B site, B is bonded in a 6-coordinate geometry to six B atoms. All B–B bond lengths are 1.84 Å. In the eighth B site, B is bonded in a 8-coordinate geometry to eight B atoms. Both B–B bond lengths are 1.87 Å. In the ninth B site, B is bonded in a 6-coordinate geometry to six B atoms. There is three shorter (1.83 Å) and two longer (1.94 Å) B–B bond length. In the tenth B site, B is bonded in a 6-coordinate geometry to six B atoms. There are a spread of B–B bond distances ranging from 1.75–1.90 Å. In the eleventh B site, B is bonded in a 7-coordinate geometry to seven B atoms. There are a spread of B–B bond distances ranging from 1.83–2.01 Å. In the twelfth B site, B is bonded in a 8-coordinate geometry to eight B atoms. There are a spread of B–B bond distances ranging from 1.72–1.79 Å. In the thirteenth B site, B is bonded in a 8-coordinate geometry to eight B atoms. In the fourteenth B site, B is bonded in a 6-coordinate geometry to six B atoms. Both B–B bond lengths are 1.78 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sn3B by Materials Project

B(Sn)3 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional and consists of two boron molecules and one Sn framework. In the Sn framework, there are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 8-coordinate geometry to eight Sn atoms. There are four shorter (3.16 Å) and four longer (3.24 Å) Sn–Sn bond lengths. In the second Sn site, Sn is bonded in a 8-coordinate geometry to eight equivalent Sn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Micrometre-scale single-crystalline borophene on a square-lattice Cu(100) surface

Borophene, a crystalline monolayer boron sheet, is a new two-dimensional (2D) quantum material, predicted to feature tunable structure, intriguing physics and to find applications in flexible electronics, energy storage and catalysis. Nanoscale borophene flakes have been synthesized on noble-metal surfaces, but for device fabrication, one needs large single-crystal domains. In this work, we report the synthesis of borophene on a square lattice Cu(100) surface and show that incommensurate coordinations could reduce the borophene-substrate interactions and alter the borophene structures in interesting ways. Micrometer-scale single-crystal domains can form as isolated faceted islands or merge together to achieve full monolayer coverage. We have discovered a new crystal structure of borophene, with ten boron atoms and two hexagonal vacancies in the unit cell. First-principle calculations indicate that charge transfer rather than covalent bonding binds 2D boron to the copper surface, and confirm its integrity and uniformity The electronic band structure features multiple anisotropic tilted Dirac cones, heralding emergent quantum fermions.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

New interaction potentials for borate glasses with mixed network formers

Here, we adapt and apply a recently developed optimization scheme used to obtain effective potentials for aluminosilicate glasses to include the network former boron into the interaction parameter set. As input data for the optimization, we used the radial distribution functions of the liquid at high temperature generated by ab initio molecular dynamics simulations, and density, coordination, and elastic modulus of glass at room temperature from experiments. The new interaction potentials are shown to reliably reproduce the structure, coordination, and mechanical properties over a wide range of compositions for binary alkali borates. Furthermore, the transferability of these new interaction parameters allows mixing to reliably reproduce the properties of various boroaluminate and borosilicate glasses.

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

Materials Data on Tl2Te3 by Materials Project

Tl2Te3 is beta Boron-derived structured and crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are two inequivalent Tl3+ sites. In the first Tl3+ site, Tl3+ is bonded in a 6-coordinate geometry to six Te2- atoms. There are a spread of Tl–Te bond distances ranging from 3.39–3.71 Å. In the second Tl3+ site, Tl3+ is bonded in a 6-coordinate geometry to six Te2- atoms. There are a spread of Tl–Te bond distances ranging from 3.52–3.75 Å. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 6-coordinate geometry to three Tl3+ and three Te2- atoms. There are a spread of Te–Te bond distances ranging from 2.88–3.27 Å. In the second Te2- site, Te2- is bonded in a 8-coordinate geometry to six Tl3+ and two Te2- atoms. The Te–Te bond length is 3.13 Å. In the third Te2- site, Te2- is bonded in a 6-coordinate geometry to three Tl3+ and three Te2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B by Materials Project

B is alpha boron-like structured and crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. there are five inequivalent B sites. In the first B site, B is bonded in a 7-coordinate geometry to seven B atoms. There are a spread of B–B bond distances ranging from 1.76–2.05 Å. In the second B site, B is bonded in a 6-coordinate geometry to six B atoms. There are a spread of B–B bond distances ranging from 1.67–1.81 Å. In the third B site, B is bonded in a 6-coordinate geometry to six B atoms. There is one shorter (1.66 Å) and two longer (1.78 Å) B–B bond length. In the fourth B site, B is bonded in a 7-coordinate geometry to seven B atoms. There is one shorter (1.74 Å) and one longer (1.90 Å) B–B bond length. In the fifth B site, B is bonded in a 6-coordinate geometry to six B atoms. The B–B bond length is 1.73 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B by Materials Project

B is alpha boron structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent B sites. In the first B site, B is bonded in a 6-coordinate geometry to six B atoms. There are a spread of B–B bond distances ranging from 1.67–1.80 Å. In the second B site, B is bonded in a 7-coordinate geometry to seven B atoms. There is two shorter (1.78 Å) and two longer (2.01 Å) B–B bond length.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O2 by Materials Project

Na2O2 is alpha boron-derived structured and crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 6-coordinate geometry to six O atoms. There are four shorter (2.34 Å) and two longer (2.40 Å) Na–O bond lengths. In the second Na site, Na is bonded in a 6-coordinate geometry to six O atoms. There are two shorter (2.42 Å) and four longer (2.49 Å) Na–O bond lengths. There are two inequivalent O sites. In the first O site, O is bonded in a 7-coordinate geometry to six Na and one O atom. The O–O bond length is 1.54 Å. In the second O site, O is bonded to six Na and one O atom to form a mixture of distorted corner, edge, and face-sharing ONa6O pentagonal bipyramids. The O–O bond length is 1.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KS by Materials Project

SK1 is alpha boron-derived structured and crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to six S1- atoms. There are two shorter (3.25 Å) and four longer (3.35 Å) K–S bond lengths. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to six S1- atoms. There are four shorter (3.17 Å) and two longer (3.25 Å) K–S bond lengths. There are two inequivalent S1- sites. In the first S1- site, S1- is bonded in a 7-coordinate geometry to six K1+ and one S1- atom. The S–S bond length is 2.13 Å. In the second S1- site, S1- is bonded in a 7-coordinate geometry to six K1+ and one S1- atom. The S–S bond length is 2.14 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaP by Materials Project

CaP is alpha boron-derived structured and crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six P2- atoms. There are two shorter (2.96 Å) and four longer (3.00 Å) Ca–P bond lengths. In the second Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six P2- atoms. There are four shorter (2.89 Å) and two longer (2.93 Å) Ca–P bond lengths. There are two inequivalent P2- sites. In the first P2- site, P2- is bonded in a 7-coordinate geometry to six Ca2+ and one P2- atom. The P–P bond length is 2.25 Å. In the second P2- site, P2- is bonded in a 7-coordinate geometry to six Ca2+ and one P2- atom. The P–P bond length is 2.31 Å.

36 MATERIALS SCIENCE↗