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Researchers at Argonne National Laboratory Report New Data on Nuclear Magnetic Resonance [Effect of Cooling Rates on Phase Separation in 0.

July 18, 2014



Researchers at Argonne National Laboratory Report New Data on Nuclear Magnetic Resonance [Effect of Cooling Rates on Phase Separation in 0.5Li(2)MnO(3)center dot 0.5LiCoO(2) Electrode Materials for Li-Ion Batteries]

By a News Reporter-Staff News Editor at Health & Medicine Week -- Data detailed on Nuclear Magnetic Resonance have been presented. According to news reporting originating from Argonne, Illinois, by NewsRx correspondents, research stated, "The results of a detailed structural investigation on the influence of cooling rates in the synthesis of lithium- and manganese-rich 0.5Li(2)MnO(3)center dot 0.5LiCoO(2) composite electrode materials, which are of interest for Li-ion battery applications, are presented. It is shown that a low-temperature, intermediate firing step, often employed in cathode synthesis, yields a minor secondary component representing a polydisperse distribution of lattice parameters, not found in the absence of low-temperature treatments."

Our news editors obtained a quote from the research from Argonne National Laboratory, "However, regardless of the heating and cooling conditions employed, all samples present two distinctly different local environments as evidenced by X-ray absorption fine structure spectroscopy (XAFS) and nuclear magnetic resonance (NMR) analysis. Transmission electron microscopy (TEM) data show discrete domain structures that are consistent with the XAFS and NMR findings. Furthermore, high resolution synchrotron X-ray diffraction (HR-XRD), as well as the XAFS and NMR data show no discernible differences between sample sets heated in similar fashion and subsequently cooled at different rates. The results contradict recent reports, using X-ray diffraction, that rapidly quenched samples of the same composition are true solid solutions. This apparent discrepancy is assigned, in part, to the inherent nature of conventional diffraction, which firmly elucidates the average long-range structure but does not capture the local domain microstructure of these nanocomposite materials."

According to the news editors, the research concluded: "The combined use of HR-XRD, XAFS, NMR, and TEM data indicate that charge ordering, which is initiated at relatively low temperatures, is the dominant force that produces a nanoscale, inhomogeneous composite structure, irrespective of the cooling rate."

For more information on this research see: Effect of Cooling Rates on Phase Separation in 0.5Li(2)MnO(3)center dot 0.5LiCoO(2) Electrode Materials for Li-Ion Batteries. Chemistry of Materials, 2014;26(11):3565-3572. Chemistry of Materials can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Chemistry of Materials - www.pubs.acs.org/journal/cmatex)

The news editors report that additional information may be obtained by contacting B.R. Long, Argonne Natl Lab, Electron Microscopy Center, Argonne, IL 60439, United States. Additional authors for this research include J.R. Croy, F. Dogan, M.R. Suchomel, B. Key, J.G. Wen, D.J. Miller, M.M. Thackeray and M. Balasubramanian (see also Nuclear Magnetic Resonance).

Keywords for this news article include: Argonne, Illinois, United States, North and Central America, Nuclear Magnetic Resonance

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Source: Health & Medicine Week


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