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All sources NASA NTRS DOE OSTI

DOE OSTI2020

Materials Data on MnCo(PO4)2 by Materials Project

MnCo(PO4)2 crystallizes in the trigonal R3 space group. The structure is three-dimensional. there are three inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six PO4 tetrahedra. There is three shorter (1.89 Å) and three longer (1.99 Å) Mn–O bond length. In the second Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six PO4 tetrahedra and a faceface with one CoO6 octahedra. There is three shorter (1.94 Å) and three longer (2.03 Å) Mn–O bond length. In the third Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six PO4 tetrahedra. There is three shorter (1.93 Å) and three longer (2.03 Å) Mn–O bond length. There are three inequivalent Co4+ sites. In the first Co4+ site, Co4+ is bonded to six O2- atoms to form distorted CoO6 octahedra that share corners with six PO4 tetrahedra, a faceface with one MnO6 octahedra, and a faceface with one CoO6 octahedra. There are three shorter (2.11 Å) and three longer (2.16 Å) Co–O bond lengths. In the second Co4+ site, Co4+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six PO4 tetrahedra and a faceface with one CoO6 octahedra. There are three shorter (1.95 Å) and three longer (2.08 Å) Co–O bond lengths. In the third Co4+ site, Co4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.16 Å) and three longer (2.17 Å) Co–O bond lengths. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two CoO6 octahedra and corners with three MnO6 octahedra. The corner-sharing octahedra tilt angles range from 29–50°. There are a spread of P–O bond distances ranging from 1.52–1.59 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two CoO6 octahedra and corners with three MnO6 octahedra. The corner-sharing octahedra tilt angles range from 27–50°. There are a spread of P–O bond distances ranging from 1.53–1.57 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Mn2+ and one P5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Mn2+, one Co4+, and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Co4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Mn2+, one Co4+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Mn2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Co4+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Mn2+, one Co4+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Mn2+ and one P5+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on MnCo(PO4)2 by Materials Project

MnCo(PO4)2 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Mn2+ is bonded to six O2- atoms to form distorted MnO6 octahedra that share corners with four equivalent CoO6 octahedra, corners with four PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–50°. There are a spread of Mn–O bond distances ranging from 1.90–2.34 Å. Co4+ is bonded to six O2- atoms to form distorted CoO6 octahedra that share corners with four equivalent MnO6 octahedra, corners with four PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–50°. There are a spread of Co–O bond distances ranging from 1.96–2.21 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CoO6 octahedra, corners with three equivalent MnO6 octahedra, and an edgeedge with one CoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–55°. There are a spread of P–O bond distances ranging from 1.52–1.57 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MnO6 octahedra, corners with three equivalent CoO6 octahedra, and an edgeedge with one MnO6 octahedra. The corner-sharing octahedra tilt angles range from 45–52°. There are a spread of P–O bond distances ranging from 1.52–1.58 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mn2+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Co4+ and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Mn2+, one Co4+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Mn2+, one Co4+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Mn2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Co4+ and one P5+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Predicting Morphological Evolution during Coprecipitation of MnCO 3 Battery Cathode Precursors Using Multiscale Simulations Aided by Targeted Synthesis

The performance of lithium-ion batteries is intimately linked to both the structure and the morphology of the cathode material, which in turn is critically linked to the synthesis conditions. However, few studies focus on understanding synthesis, especially during the coprecipitation of metal oxide precursors, a process that largely determines the final morphology of the material. In this paper, we go beyond the typical equilibrium particle shape analysis conducted in the literature and incorporate kinetic aspects of morphology evolution. We perform these studies using controlled synthesis on a well-defined metal salt system (MnCO 3 ) combined with multiscale simulations and high-resolution microscopy. Results show that with increasing metal concentration, the particles transition from rhombohedral to cubic to spherical shapes. Computational analysis using density functional theory (DFT) reveals that rhombohedral shaped particles evolve under equilibrium conditions. Phase field techniques indicate that at higher metal concentrations, fast growth kinetics of the precipitates result in the transition to cubic and, subsequently, spherical shapes, accompanied by a decrease in particle size. This study, while limited to the one metal salt system, provides an approach to shed light on the synthesis process of mixed transition metal salts, gradient materials, and other cathode materials of interest to the battery community.

25 ENERGY STORAGE↗

DOE OSTI2020

Materials Data on MnCo by Materials Project

CoMn is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mn is bonded in a body-centered cubic geometry to eight equivalent Co atoms. All Mn–Co bond lengths are 2.47 Å. Co is bonded in a body-centered cubic geometry to eight equivalent Mn atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Water film-driven Mn (oxy)(hydr)oxide nanocoating growth on rhodochrosite

Minerals exposed to moist air stabilize thin water films that drive a score of chemical reactions of great importance to water-unsaturated terrestrial environments. In this study, we identified Mn (oxy)(hydr)oxide nanocoatings formed by the dissolution, oxidation and precipitation of Mn in oxygenated water films grown on rhodochrosite (MnCO 3 ) microparticles. Nanocoatings that could be identified by vibrational spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and (scanning and transmission) electron microscopy formed in water films containing the equivalent of at least 7 monolayers (~84 H 2 O/nm 2 ). These films were formed by exposing microparticles to moist air with at least 50% relative humidity (RH). Films of neutral pH reacted up to 14% of the Mn II located in the topmost ~5 nm region of the microparticles in atmospheres of up to 90% RH for 7 d. These reactions produced MnOOH, birnessite (MnO 2 ) and hausmannite (Mn 3 O 4 ) nanoparticles of low crystallinity, while exposure to atmospheric air for 1 yr. converted only 2% of Mn II in this region to MnOOH. In contrast, reactions in alkaline water films converted up to ~75% of the Mn II but only after 16 d of reaction. These films produced MnOOH and MnO 2 of low crystallinity, as well as crystalline hausmannite. Kinetic modeling of the time-resolved growth of the Mnsingle bondO stretching vibrational bands of these nanocoatings revealed two concurrent reaction processes. A 1 rst -order process was assigned to nucleation events terminating only after a few hours, and a 0-order process was assigned to the sustained growth of nanocoatings from these nuclei over longer reaction time. By identifying nanocoatings formed by water film-driven reactions on rhodochrosite, our study adds new insight into mineralogical transformations relevant to anoxic–oxic boundaries in water-unsaturated environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Conductive spinels derived from Co–Mn based alloy precursor for SOFC cathode-side contact application

The utilization of gas-atomized Co–Mn based alloy precursor is a promising approach to lowering the sintering temperature of the spinel contact layer and enhancing its performance. In this work, simulated interconnect/contact/cathode cells are employed to investigate the effects of different metallic precursors (i.e., three Co–Mn based alloy powders and a mixture of Co + MnO 2 powders) on the microstructure and performance of the reactively-sintered MnCo 2 O 4 -based contact layer. While excellent overall electrical performance is observed for all the cells with the four contact precursors during 1000-h testing at 800 °C in air, the cell with the Ce-doped alloy contact precursor shows the lowest cell area specific resistance (ASR) and ASR degradation rate. Cross-sectional observation of the tested cells is conducted to assess the compatibility of the contact layer with adjacent components as well as its effectiveness in reducing the Cr 2 O 3 scale growth and blocking Cr migration from the interconnect to the cathode.

08 HYDROGEN↗

DOE OSTI2021

Observation of nuclear-spin Seebeck effect

Thermoelectric effects have been applied to power generators and temperature sensors that convert waste heat into electricity. The effects, however, have been limited to electrons to occur, and inevitably disappear at low temperatures due to electronic entropy quenching. Here, we report thermoelectric generation caused by nuclear spins in a solid: nuclear-spin Seebeck effect. The sample is a magnetically ordered material MnCO 3 having a large nuclear spin ( I = 5/2) of 55 Mn nuclei and strong hyperfine coupling, with a Pt contact. In the system, we observe low-temperature thermoelectric signals down to 100 mK due to nuclear-spin excitation. Our theoretical calculation in which interfacial Korringa process is taken into consideration quantitatively reproduces the results. The nuclear thermoelectric effect demonstrated here offers a way for exploring thermoelectric science and technologies at ultralow temperatures.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2020

Anoxic photogeochemical oxidation of manganese carbonate yields manganese oxide

The oxidation states of manganese minerals in the geological record have been interpreted as proxies for the evolution of molecular oxygen in the Archean eon. In this paper we report that an Archean manganese mineral, rhodochrosite (MnCO 3 ), can be photochemically oxidized by light under anoxic, abiotic conditions. Rhodochrosite has a calculated bandgap of about 5.4 eV, corresponding to light energy centering around 230 nm. Light at that wavelength would have been present on Earth’s surface in the Archean, prior to the formation of stratospheric ozone. We show experimentally that the photooxidation of rhodochrosite in suspension with light centered at 230 nm produced H 2 gas and manganite (γ-MnOOH) with an apparent quantum yield of 1.37 × 10 –3 moles hydrogen per moles incident photons. Our results suggest that manganese oxides could have formed abiotically on the surface in shallow waters and on continents during the Archean eon in the absence of molecular oxygen.

58 GEOSCIENCES↗

DOE OSTI2023

Chromium Tolerant, Highly Active and Stable Electrocatalytic Internal Surface Coating for Cathode of Commercial SOFCs (Final Report)

This project is aimed to develop a chromium (Cr) tolerant, highly active, and stable coating layer on the internal surfaces of the porous composite cathode from commercially available SOFCs. Such coating layer was developed using the additive manufacturing process of Atomic Layer Deposition (ALD) and has been applied on the cathode consisting of either an electronic conductor of LaxSr 1-x MnyO 3-δ (LSM) or mixed ionic and electronic conducting La x Sr 1-x Co y Fe 1-y O 3-δ (LSCF). PI's work has demonstrated that the internal surface of cathode from the commercial cells, can be further tailored using ALD coating to dramatically enhance the cell performance. For instance, ALD layer consisting heterostructured nano composite of nano-Pt and nano-(Mn 0.8 Co 0.2 ) 3 O 4 oxide on the internal surface of porous LSM/YSZ cathode from SOFCs, has resulted in the large reduction of the cell polarizations resistance by up to 53%, and enormous increase of power density over 370%. For the cells with LSCF/Sm 2 O 3 doped CeO 2 (SDC) cathode, the conformal layer of nano-composite consisting of superjacent CoOx and subjacent minimum amount of Pt nano-grains has resulted in the power density enhancement by 126% for the large scale industry tubular cells at 750°C, and both the performance enhancement and nanostructure of the ALD layer are stable over ~ 2000 h continuous operation performed at industry test station. In the meanwhile, those ALD coating layer developed by PI's work is also inherently Cr-tolerant, and could act as physical barrier for preventing Cr diffusion into the cathode backbone, so as to mitigate the Cr poisoning effect on the cathode. In this project, the impact of Cr on the performance of those ALD coated commercial cells has been evaluated. Based on evolution of the cell performance, the ALD coating layer chemistry and ALD coating layer thickness has been optimized to maximize the overall Cr tolerance, cell power density and cell longevity. Different ALD coating has been applied onto the internal surface of LSM/YSZ and LSCF/SDC backbone respectively. The architecture/scaffold structures on the internal surface of different cathode, designed by this project, was catalogued and analyzed using High Resolution Transmission Electron Microscopy (HRTEM), and cell power/durability performance are assured via comprehensive electrochemical performance testing in the industry operation relevant conditions. The impact of the electrochemical operation current density, the water humidity, the cell operation temperature, and cell operation duration on the Cr tolerance of ALD coated cells has been systematically investigated. There is completely different nanostructure degradation mechanisms between LSM and LSCF cells induced by Cr contamination. For the LSCF/SDC baseline cell, With the Cr source, there is no apparent Sr surface segregation phase even for the baseline cell operated for 3000 h at 750 °C. With the Cr source, there is significant amorphous (SrCr)Ox phase accumulated in the original pore region. For the commercial baseline cells, Cr contaminants on the LSM electrode severely impacted the entire cell's electrochemical performance and nanostructure degradation. Those degradations include (1). Peak power density loss of 64 % after 109 h of operation. The dramatic increase in Rp (2). They are cracking at LSM/SSZ interface, LSM grains. SSZ remains intact but with (CrMn)Ox. By contrast, ALD coating (MnCo)Ox/Pt dramatically improves the Cr resistance, as follows (1). ALD-coated cell with a power density is 280-380 % of the baseline cell, depending on the ALD layer thickness. (2). For a cell with a 20 nm thick ALD layer, there is a large performance enhancement (> 200 % power density) induced by ALD coating of Cr-tolerant Mn 0.8 Co 0.2 Ox. (3). For a cell with a 20 nm thick ALD layer, after 168 h at 750 °C power density of the ALD-coated cell is ~ 600% of that baseline cell upon operation with Cr contamination for 109 h. The ALD coating on the internal surface of cathode developed by this project integrated multi-functions. Those multi-functions include (1). Dramatically improving the cell power density for the commercial cells; (2). Dramatically improving contamination resistance of the cathode, for being an excellent protection coating layer sealing off Cr contamination. (3). Dramatically increasing the cell longevity by potentially preventing the microstructure evolution and grain coarsening of the cathode. Overall, this project will provide a simple solution to simultaneously enhance power density and increase the reliability, robustness, and endurance of commercial SOFCs, over the entire operating temperature range of 650-800 °C. For the inherently functional SOFC, the ALD coating of LSM based cathode mitigate the Cr-contamination. Power density of ALD-coated cell is ~ 600% of that baseline cell upon operation with Cr contamination. In addition to SOFCs, the novel on-demand design approach and creation of multifunctional heterogeneous architecture on the electrode surface presented in this work opens further research for their application in other types of fuel cells, batteries, and sensors for which electrochemical reactions on the surface are similarly critical.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Freeze-induced crystallization: An overlooked pathway for mineral genesis in natural waters

Natural ice plays salient roles in making the Earth habitable and sustainable. Previously overlooked, its role in chemical processes is now of emerging interest, particularly due to the freeze concentration effect, which can substantially promote chemical reactions during ice formation. We demonstrate here that ice formation can serve as a dynamic and unique pathway for mineral genesis. Freezing solutions containing dissolved manganese and carbonates produced rhodochrosite (Mn II CO 3 ) even under slightly undersaturated conditions. At room temperature, by contrast, this occurred when the solution saturation level was increased by ca. 30,000 times. The cryogenic rhodochrosite formed spherical aggregates of nano-polycrystallites, distinctly different from the cubic monocrystalline particles observed at room temperature. The distinct feature likely resulted from the combined effects of the intensified supersaturation induced by the freeze concentration effect and the low temperatures within liquid-like layers, conditions that make liquid-like layers an exceptional environment for mineral genesis, unlike typical natural water systems. The cryogenic rhodochrosite formation was successfully demonstrated using in situ, real-time X-ray absorption spectroscopy (XAS), enabling direct observation of freeze-induced solid formation. In conclusion, our findings reveal that freeze-induced crystallization may be an active mineralization pathway, potentially influencing elemental cycles within the cryosphere and contributing to minerals with distinguishing properties and reactivities in the environment.

Earth, Atmospheric, and Planetary Sciences↗