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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Electrochemical Reduction of Ag 2 VP 2 O 8 Composite Electrodes Visualized via In situ Energy Dispersive X-ray Diffraction (EDXRD). Unexpected Conductive Additive Effects

In our study, we characterize the deposition of silver metal nanoparticles formed during discharge of Li/Ag 2 VP 2 O 8 cells with composite cathodes containing conductive carbon additive. Using in situ energy dispersive X-ray diffraction (EDXRD) of an intact battery, the location and distribution of silver metal nanoparticles generated upon reduction-displacement deposition within an Ag 2 VP 2 O 8 cathode containing a pre-existing percolation network can be observed for the first time. Our study yielded unexpected results where higher rate initial discharge generated a more effective conductive matrix. This stands in contrast to cells with cathodes with no conductive additive where a low rate initial discharge proved more effective. Our results provide evidence that using conductive additives in conjunction with an in situ reduction-displacement deposition of silver metal provides a path toward the ultimate goal of complete electrical contact and full utilization of all electroactive particles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Visualization of structural evolution and phase distribution of a lithium vanadium oxide (Li 1.1 V 3 O 8 ) electrode via an operando and in situ energy dispersive X-ray diffraction technique

We present Li 1+n V 3 O 8 (n = 0–0.2) has been extensively investigated as a cathode material for Li ion batteries because of its superior electrochemical properties including high specific energy and good rate capability. In this paper, a synchrotron based energy dispersive X-ray diffraction (EDXRD) technique was employed to profile the phase transitions and the spatial phase distribution of a Li 1.1 V 3 O 8 electrode during electrochemical (de)lithiation in situ and operando. As annealing temperature during the preparation of the Li 1.1 V 3 O 8 material has a strong influence on the morphology and crystallinity, and consequently influences the electrochemical outcomes of the material, Li 1.1 V 3 O 8 materials prepared at two different temperatures, 500 and 300°C (LVO500 and LVO300), were employed in this study. The EDXRD spectra of LVO500 and LVO300 cells pre-discharged at C/18, C/40 and C/150 were recorded in situ, and phase localization and relative intensity of the peaks were compared. For cells discharged at the C/18 rate, although α and β phases were distributed uniformly within the LVO500 electrode, they were localized on two sides of the LVO300 electrode. Discharging rates of C/40 and C/150 led to homogeneous β phase formation in both LVO500 and LVO300 electrodes. Furthermore, the phase distribution as a function of position and (de)lithiation extent was mapped operando as the LVO500 cell was (de)lithiated. In conclusion, the operando data indicate that (1) the lithiation reaction initiated from the side of the electrode facing the Li anode and proceeded towards the side facing the steel can, (2) during discharge the phase transformation from a Li-poor to a Li-rich α phase and the formation of a β phase can proceed simultaneously in the electrode after the first formation of a β phase, and (3) the structural evolution occurring during charging is not the reverse of that during discharge and takes place homogenously throughout the electrode.

25 ENERGY STORAGE↗
DOE OSTI2014

Multidimensional Visualization of MHD and Turbulence in Fusion Plasmas [Multi-dimensional Visualization of Turbulence in Fusion Plasmas]

Here, quasi-optical imaging at sub-THz frequencies has had a major impact on fusion plasma diagnostics. Mm-wave imaging reflectometry utilizes microwaves to actively probe fusion plasmas, inferring the local properties of electron density fluctuations. Electron cyclotron emission imaging is a multichannel radiometer that passively measures the spontaneous emission of microwaves from the plasma to infer local properties of electron temperature fluctuations. These imaging diagnostics work together to diagnose the characteristics of turbulence. Important quantities such as amplitude and wavenumber of coherent fluctuations, correlation lengths and decor relation times of turbulence, and poloidal flow velocity of the plasma are readily inferred.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2017

High resolution visualization and exo-proteomics reveal the physiological role of XlnR and AraR in plant biomass colonization and degradation by Aspergillus niger : Visualizing plant biomass degradation by A. niger

In A. niger, two transcription factors, AraR and XlnR, regulate the production of enzymes involved in degradation of arabinoxylan and catabolism of the released L-arabinose and D-xylose. Deletion of both araR and xlnR in leads to reduced production of (hemi)cellulolytic enzymes and reduced growth on arabinan, arabinogalactan and xylan. In this study, we investigated the colonization and degradation of wheat bran by the A. niger reference strain CBS 137562 and araR/xlnR regulatory mutants using highresolution microscopy and exo-proteomics. We discovered that wheat bran flakes have a ‘rough’ and ‘smooth’ surface with substantially different affinity towards fungal hyphae. While colonization of the rough side was possible for all strains, the xlnR mutants struggled to survive on the smooth side of the wheat bran particles after 20 and 40 h post inoculation. Impaired colonization ability of the smooth surface of wheat bran was linked to reduced potential of DxlnR to secrete arabinoxylan and cellulosedegrading enzymes and indicates that XlnR is the major regulator that drives colonization of wheat bran in A. niger.

Kowalczyk, Joanna E.↗