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8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Mn3O4 by Materials Project

Mn3O4 is Hausmannite structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are four inequivalent Mn+2.67+ sites. In the first Mn+2.67+ site, Mn+2.67+ is bonded to four O2- atoms to form corner-sharing MnO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–60°. There are three shorter (2.07 Å) and one longer (2.08 Å) Mn–O bond lengths. In the second Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six equivalent MnO4 tetrahedra and edges with six MnO6 octahedra. There are four shorter (1.97 Å) and two longer (2.33 Å) Mn–O bond lengths. In the third Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six equivalent MnO4 tetrahedra and edges with six MnO6 octahedra. There are a spread of Mn–O bond distances ranging from 1.96–2.33 Å. In the fourth Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six equivalent MnO4 tetrahedra and edges with six MnO6 octahedra. There are four shorter (1.96 Å) and two longer (2.32 Å) Mn–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four Mn+2.67+ atoms to form a mixture of distorted edge and corner-sharing OMn4 trigonal pyramids. In the second O2- site, O2- is bonded to four Mn+2.67+ atoms to form a mixture of distorted edge and corner-sharing OMn4 trigonal pyramids. In the third O2- site, O2- is bonded to four Mn+2.67+ atoms to form a mixture of distorted edge and corner-sharing OMn4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn3O4 by Materials Project

Mn3O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twelve inequivalent Mn+2.67+ sites. In the first Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing MnO6 octahedra. The corner-sharing octahedra tilt angles range from 2–3°. There are a spread of Mn–O bond distances ranging from 2.09–2.52 Å. In the second Mn+2.67+ site, Mn+2.67+ is bonded in a see-saw-like geometry to four O2- atoms. There are a spread of Mn–O bond distances ranging from 1.88–1.90 Å. In the third Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are a spread of Mn–O bond distances ranging from 2.09–2.47 Å. In the fourth Mn+2.67+ site, Mn+2.67+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mn–O bond distances ranging from 2.09–2.60 Å. In the fifth Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form distorted MnO6 octahedra that share a cornercorner with one MnO6 octahedra, corners with two equivalent MnO5 square pyramids, edges with four MnO6 octahedra, and an edgeedge with one MnO5 square pyramid. The corner-sharing octahedral tilt angles are 3°. There are a spread of Mn–O bond distances ranging from 2.09–2.40 Å. In the sixth Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mn–O bond distances ranging from 2.10–2.41 Å. In the seventh Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mn–O bond distances ranging from 2.08–2.52 Å. In the eighth Mn+2.67+ site, Mn+2.67+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mn–O bond distances ranging from 2.09–2.61 Å. In the ninth Mn+2.67+ site, Mn+2.67+ is bonded in a see-saw-like geometry to four O2- atoms. There is two shorter (1.88 Å) and two longer (1.89 Å) Mn–O bond length. In the tenth Mn+2.67+ site, Mn+2.67+ is bonded to five O2- atoms to form distorted MnO5 square pyramids that share corners with two equivalent MnO6 octahedra, an edgeedge with one MnO6 octahedra, and edges with two equivalent MnO5 square pyramids. The corner-sharing octahedral tilt angles are 3°. There are a spread of Mn–O bond distances ranging from 2.08–2.15 Å. In the eleventh Mn+2.67+ site, Mn+2.67+ is bonded in a distorted see-saw-like geometry to four O2- atoms. There are a spread of Mn–O bond distances ranging from 1.86–1.91 Å. In the twelfth Mn+2.67+ site, Mn+2.67+ is bonded in a see-saw-like geometry to four O2- atoms. There are a spread of Mn–O bond distances ranging from 1.86–1.91 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded to four Mn+2.67+ atoms to form a mixture of distorted edge and corner-sharing OMn4 trigonal pyramids. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Mn+2.67+ atoms. In the third O2- site, O2- is bonded in a square co-planar geometry to four Mn+2.67+ atoms. In the fourth O2- site, O2- is bonded in a square co-planar geometry to four Mn+2.67+ atoms. In the fifth O2- site, O2- is bonded to four Mn+2.67+ atoms to form a mixture of distorted edge and corner-sharing OMn4 trigonal pyramids. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to four Mn+2.67+ atoms. In the seventh O2- site, O2- is bonded in a distorted see-saw-like geometry to four Mn+2.67+ atoms. In the eighth O2- site, O2- is bonded to four Mn+2.67+ atoms to form a mixture of distorted edge and corner-sharing OMn4 trigonal pyramids. In the ninth O2- site, O2- is bonded to four Mn+2.67+ atoms to form distorted corner-sharing OMn4 trigonal pyramids. In the tenth O2- site, O2- is bonded to four Mn+2.67+ atoms to form a mixture of distorted edge and corner-sharing OMn4 trigonal pyramids. In the eleventh O2- site, O2- is bonded to four Mn+2.67+ atoms to form a mixture of distorted edge and corner-sharing OMn4 trigonal pyramids. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to three Mn+2.67+ atoms. In the thirteenth O2- site, O2- is bonded to four Mn+2.67+ atoms to form a mixture of distorted edge and corner-sharing OMn4 trigonal pyramids. In the fourteenth O2- site, O2- is bonded in a distorted see-saw-like geometry to four Mn+2.67+ atoms. In the fifteenth O2- site, O2- is bonded in a square co-planar geometry to four Mn+2.67+ atoms. In the sixteenth O2- site, O2- is bonded in a square co-planar geometry to four Mn+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn3O4 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↗
DOE OSTI2025

Unveiling the Mechanism of Mn Dissolution Through a Dynamic Cathode‐Electrolyte Interphase on LiMn2O4

Abstract Understanding the formation and evolution of the cathode‐electrolyte interphase (CEI), which forms at the interface between the cathode and electrolyte, is crucial for revealing degradation mechanisms in cathode materials, especially for developing strategies to stabilize the interphase in the strongly oxidizing conditions that evolve at high operating voltages in next‐generation Li‐ion batteries. However, The present understanding of the CEI is challenged by its complex and dynamic nature. In this work, near‐edge X‐ray absorption fine structure spectroscopy, electrochemical characterization, and reactive molecular dynamics simulations are combined to reveal a mechanism for CEI formation and evolution above model LiMn 2 O 4 (LMO) thin‐film electrodes in contact with conventional carbonate‐based electrolytes. It is found that Mn dissolution from LMO can be understood in terms of repetitive Mn 3 O 4 formation and dissolution behavior during cycling, which is closely connected to electrolyte decomposition and a key aspect of the CEI formation and growth. The behavior of the CEI in this model system offers detailed insight into the dynamic chemistry of the interphase, underscoring the important role of electrolyte composition and cathode surface structure in interphase degradation.

Ou, Wenhan↗
DOE OSTI2024

Use of Hydrogel Electrolyte in Zn-MnO2 Rechargeable Batteries: Characterization of Safety, Performance, and Cu2+ Ion Diffusion

Achieving commercially acceptable Zn-MnO2 rechargeable batteries depends on the reversibility of active zinc and manganese materials, and avoiding side reactions during the second electron reaction of MnO2. Typically, liquid electrolytes such as potassium hydroxide (KOH) are used for Zn-MnO2 rechargeable batteries. However, it is known that using liquid electrolytes causes the formation of electrochemically inactive materials, such as precipitation Mn3O4 or ZnMn2O4 resulting from the uncontrollable reaction of Mn3+ dissolved species with zincate ions. In this paper, hydrogel electrolytes are tested for MnO2 electrodes undergoing two-electron cycling. Improved cell safety is achieved because the hydrogel electrolyte is non-spillable, according to standards from the US Department of Transportation (DOT). The cycling of “half cells” with advanced-formulation MnO2 cathodes paired with commercial NiOOH electrodes is tested with hydrogel and a normal electrolyte, to detect changes to the zincate crossover and reaction from anode to cathode. These half cells achieved ≥700 cycles with 99% coulombic efficiency and 63% energy efficiency at C/3 rates based on the second electron capacity of MnO2. Other cycling tests with “full cells” of Zn anodes with the same MnO2 cathodes achieved ~300 cycles until reaching 50% capacity fade, a comparable performance to cells using liquid electrolyte. Electrodes dissected after cycling showed that the liquid electrolyte allowed Cu ions to migrate more than the hydrogel electrolyte. However, measurements of the Cu diffusion coefficient showed no difference between liquid and gel electrolytes; thus, it was hypothesized that the gel electrolytes reduced the occurrence of Cu short circuits by either (a) reducing electrode physical contact to the separator or (b) reducing electro-convective electrolyte transport that may be as important as diffusive transport.

25 ENERGY STORAGE↗
NASA NTRS2004

Direct Electrolytic Deposition of Mats of Mn(x)O(y) Nanowires

Mats of free-standing manganese oxide (MnxOy) nanowires have been fabricated as experimental electrode materials for rechargeable electrochemical power cells and capacitors. Because they are free-standing, the wires in these mats are electrochemically accessible. The advantage of the mat-of-nanowires configuration, relative to other configurations of electrode materials, arises from the combination of narrowness and high areal number density of the wires. This combination offers both high surface areas for contact with electrolytes and short paths for diffusion of ions into and out of the electrodes, thereby making it possible to charge and discharge at rates higher than would otherwise be possible and, consequently, to achieve greater power densities. The nanowires are fabricated in an electrolytic process in which there is no need for an electrode binder material. Moreover, there is no need to incorporate an electrically conductive additive into the electrode material; the only electrically conductive material that must be added is a thin substrate contact film at the anchored ends of the nanowires. Hence, the mass fraction of active electrode material is close to 100 percent, as compared with about 85 percent in conventional electrodes made from a slurry of active electrode material, binder, and conductive additive pressed onto a metal foil. The locations and sizes of the nanowires are defined by holes in templates in the form of commercially available porous alumina membranes. In experiments to demonstrate the present process, alumina membranes of various pore sizes and degrees of porosity were used. First, a film of Au was sputtered onto one side of each membrane. The membranes were then attached, variously, to carbon tape or a gold substrate by use of silver or carbon paste. Once thus attached, the membranes were immersed in a plating solution comprising 0.01 M MnSO4 + 0.03 M (NH4)2SO4. The pH of the solution was kept constant at 8 by addition of H2SO4 or NH4OH as needed. Mn(x)O(y) nanowires were potentiostatically electrodeposited in the pores in the alumina templates. Depending on the anodic deposition potentials, Mn(x)O(y) was deposited in various oxidation states [divalent (Mn3O4), trivalent (Mn2O3), or tetravalent (MnO2)]. The Mn(x)O(y) wires were made free-standing (see figure) by dissolving the alumina templates, variously, in KOH or NaOH at a concentration of 20 volume percent.

Myung, Nosang↗
DOE OSTI2024

Measuring 3D Chemistry at 1 nm Resolution with Fused Multi-Modal Electron Tomography

Measuring the three-dimensional (3D) distribution of chemistry in nanoscale matter is a longstanding challenge for metrological science. The inelastic scattering events required for 3D chemical imaging are too rare, requiring high beam exposure that destroys the specimen before an experiment is completed. Even larger doses are required to achieve high resolution. Thus, chemical mapping in 3D has been unachievable except at lower resolution with the most radiation-hard materials. Here, high-resolution 3D chemical imaging is achieved near or below one-nanometer resolution in an Au-Fe3O4 metamaterial within an organic ligand matrix, Co3O4-Mn3O4 core-shell nanocrystals, and ZnS-Cu0.64S0.36 nanomaterial using fused multi-modal electron tomography. Multi-modal data fusion enables high-resolution chemical tomography often with 99% less dose by linking information encoded within both elastic (HAADF) and inelastic (EDX/EELS) signals. We thus demonstrate that sub-nanometer 3D resolution of chemistry is measurable for a broad class of geometrically and compositionally complex materials.

Schwartz, Jonathan↗