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16 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Whole-Voltage-Range Oxygen Redox in P2-Layered Cathode Materials for Sodium-Ion Batteries

Oxygen-redox of layer-structured metal-oxide cathodes has drawn great attention as an effective approach to break through the bottleneck of their capacity limit. However, reversible oxygen-redox can only be obtained in the high-voltage region (usually over 3.5 V) in current metal-oxide cathodes. Here, we realize reversible oxygen-redox in a wide voltage range of 1.5-4.5 V in a P2-layered Na 0.7 Mg 0.2 [Fe 0.2 Mn 0.6 $\square$0.2]O 2 cathode material, where intrinsic vacancies are located in transition-metal (TM) sites and Mg-ions are located in Na sites. Mg-ions in the Na layer serve as "pillars" to stabilize the layered structure during electrochemical cycling, especially in the high-voltage region. Intrinsic vacancies in the TM layer create the local configurations of "$\square$-O-$\square$", "Na-O-$\square$" and "Mg-O-$\square$" to trigger oxygen-redox in the whole voltage range of charge-discharge. Additionally, time-resolved techniques demonstrate that the P2 phase is well maintained in a wide potential window range of 1.5-4.5 V even at 10 C. It is revealed that charge compensation from Mn- and O-ions contributes to the whole voltage range of 1.5-4.5 V, while the redox of Fe-ions only contributes to the high-voltage region of 3.0-4.5 V. The orphaned electrons in the nonbonding 2p orbitals of O that point toward TM-vacancy sites are responsible for reversible oxygen-redox, and Mg-ions in Na sites suppress oxygen release effectively.

25 ENERGY STORAGE↗
DOE OSTI2021

Binding and stability of MgO monomers on anatase TiO 2 (101)

In catalysis, MgO is often used to modify the acid-base properties of support oxides and to stabilize supported metal atoms and particles on oxides. In this study, we show how the sublimation of MgO powder can be used to deposit MgO monomers, hither on anatase TiO 2 (101). A combination of X-ray electron spectroscopy, high-resolution scanning tunneling microscopy, and density functional theory is employed to gain insight into the MgO monomer binding, electronic and vibrational properties, and thermal stability. In the most stable configuration, the Mg and O of the MgO monomer bind to two surface oxygens and one undercoordinated surface titanium, respectively. The additional binding weakens the Mg-O monomer bond and makes the Mg more ionic. The monomers are thermally stable up to 650 K, where the onset of diffusion into the TiO 2 bulk is observed. Finally, the monomeric MgO species on TiO 2 (101) represent an ideal, atomically precise system with modified acid-base properties and will be employed in our future catalytic studies.

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

Materials Data on MgO by Materials Project

MgO is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mg2+ is bonded to six equivalent O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.13 Å. O2- is bonded to six equivalent Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO2 by Materials Project

MgO2 is Pyrite-like structured and crystallizes in the cubic Pa-3 space group. The structure is three-dimensional. Mg is bonded to six equivalent O atoms to form MgO6 octahedra that share corners with twelve equivalent MgO6 octahedra and corners with six equivalent OMg3O tetrahedra. The corner-sharing octahedral tilt angles are 69°. All Mg–O bond lengths are 2.11 Å. O is bonded to three equivalent Mg and one O atom to form OMg3O tetrahedra that share corners with three equivalent MgO6 octahedra and corners with fifteen equivalent OMg3O tetrahedra. The corner-sharing octahedral tilt angles are 72°. The O–O bond length is 1.51 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO by Materials Project

MgO is Wurtzite structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Mg2+ is bonded to four equivalent O2- atoms to form corner-sharing MgO4 tetrahedra. There are three shorter (1.99 Å) and one longer (2.02 Å) Mg–O bond lengths. O2- is bonded to four equivalent Mg2+ atoms to form corner-sharing OMg4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO by Materials Project

MgO is Moissanite-4H structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- atoms to form corner-sharing MgO4 tetrahedra. There is one shorter (1.99 Å) and three longer (2.00 Å) Mg–O bond length. In the second Mg2+ site, Mg2+ is bonded to four O2- atoms to form corner-sharing MgO4 tetrahedra. There are three shorter (2.00 Å) and one longer (2.01 Å) Mg–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four Mg2+ atoms to form corner-sharing OMg4 tetrahedra. In the second O2- site, O2- is bonded to four Mg2+ atoms to form corner-sharing OMg4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO by Materials Project

MgO is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mg2+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Mg–O bond lengths are 2.30 Å. O2- is bonded in a body-centered cubic geometry to eight equivalent Mg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO by Materials Project

MgO is Tungsten Carbide structured and crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Mg2+ is bonded to six equivalent O2- atoms to form a mixture of distorted edge, face, and corner-sharing MgO6 pentagonal pyramids. All Mg–O bond lengths are 2.16 Å. O2- is bonded to six equivalent Mg2+ atoms to form a mixture of distorted edge, face, and corner-sharing OMg6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO by Materials Project

MgO is Molybdenum Carbide MAX Phase-like structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing MgO6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 2°. All Mg–O bond lengths are 2.17 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.12 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.12 Å. In the fourth Mg2+ site, Mg2+ is bonded to six equivalent O2- atoms to form a mixture of corner and edge-sharing MgO6 octahedra. All Mg–O bond lengths are 2.12 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to six equivalent Mg2+ atoms to form a mixture of corner and edge-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of corner and edge-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the third O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of corner, edge, and face-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–47°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of corner, edge, and face-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–47°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO2 by Materials Project

MgO2 is pyrite-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Mg is bonded to six equivalent O atoms to form edge-sharing MgO6 octahedra. All Mg–O bond lengths are 2.11 Å. O is bonded in a 4-coordinate geometry to three equivalent Mg and one O atom. The O–O bond length is 1.49 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO by Materials Project

MgO is Molybdenum Carbide MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.12 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.12 Å. In the third Mg2+ site, Mg2+ is bonded to six equivalent O2- atoms to form a mixture of distorted edge and corner-sharing MgO6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 2°. All Mg–O bond lengths are 2.17 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to six equivalent Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of face, edge, and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–47°. In the third O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO by Materials Project

MgO crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mg2+ is bonded to five equivalent O2- atoms to form a mixture of corner and edge-sharing MgO5 trigonal bipyramids. There are three shorter (2.03 Å) and two longer (2.12 Å) Mg–O bond lengths. O2- is bonded to five equivalent Mg2+ atoms to form a mixture of corner and edge-sharing OMg5 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO by Materials Project

MgO crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. Mg2+ is bonded to four equivalent O2- atoms to form a mixture of distorted edge and corner-sharing MgO4 tetrahedra. All Mg–O bond lengths are 1.99 Å. O2- is bonded to four equivalent Mg2+ atoms to form a mixture of distorted edge and corner-sharing OMg4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO2 by Materials Project

MgO2 is Calaverite structured and crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one MgO2 sheet oriented in the (0, 0, 1) direction. Mg is bonded to six equivalent O atoms to form distorted edge-sharing MgO6 octahedra. There are four shorter (2.07 Å) and two longer (2.16 Å) Mg–O bond lengths. O is bonded in a trigonal non-coplanar geometry to three equivalent Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgO by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗