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Ishida N.,Japan National Institute of Materials Science | Fukumitsu H.,Sumika Chemical Analysis Service SCAS Ltd. | Fujita D.,Japan National Institute of Materials Science
Journal of the Vacuum Society of Japan | Year: 2015

The demand for measurement tools to detect Li with high spatial resolution and precise chemical sensitivity is increasing with the spread of lithium-ion batteries (LIBs) for use in a wide range of applications. In this article, a brief review will be given on recent progress in the chemical state imaging of Li using scanning Auger electron microscopy (SAM). We report a novel method that enables a precise evaluation of oxidation states of Li by the combined use of Auger electron spectroscopy and electron energy loss spectroscopy signals for elemental mapping. Also, we summarize the characterization of spatial distribution of Li in electrochemically lithiated graphite anodes, as an example of application of SAM to the evaluation of actual LIB materials. Source


Matsui H.,Japan National Institute of Advanced Industrial Science and Technology | Kumaki D.,Yamagata University | Takahashi E.,Japan National Institute of Advanced Industrial Science and Technology | Takahashi E.,Sumika Chemical Analysis Service SCAS Ltd. | And 4 more authors.
Materials Research Society Symposium Proceedings | Year: 2012

We investigated the anisotropic g tensors of nine kinds of organic semiconductor molecules in the cationic state by density functional theory (DFT) calculations. Large anisotropy was obtained in sulfur-containing molecules because of the large spin-orbit coupling at the sulfur atoms. The calculated g values were validated by electron spin resonance (ESR) experiments for the cation radicals in solution. © 2012 Materials Research Society. Source


Ishida N.,Japan National Institute of Materials Science | Fukumitsu H.,Japan National Institute of Materials Science | Fukumitsu H.,Sumika Chemical Analysis Service SCAS Ltd. | Kimura H.,Sumika Chemical Analysis Service SCAS Ltd. | Fujita D.,Japan National Institute of Materials Science
Journal of Power Sources | Year: 2014

The spatial distribution of Li ions in electrochemically lithiated graphite anodes for Li-ion battery is characterized by scanning Auger electron microscopy. We show that direct mapping of Li KVV peak intensity reveal the spatial distribution of intercalated Li and its chemical state in a quantitative manner. Furthermore, we demonstrate that mapping using a C KVV peak also reflects the spatial distribution of Li due to the change in the electronic properties of C atoms induced by the electrode reaction (Li intercalation). Mapping measurements on three samples with different charging states (20%, 50%, and 100%) show that at the early stage of charging Li ions do not intercalate homogenously into all the graphite particles but selectively into some specific ones with higher rates. Our method provides the criteria to evaluate structure-correlated Li intercalation from nanometer- to micrometer-scale, such as conductivity network in the electrodes due to a non-uniform morphology of binder and conductive additives. © 2013 Elsevier B.V. All rights reserved. Source


Fukumitsu H.,Sumika Chemical Analysis Service SCAS Ltd. | Omori M.,Sumika Chemical Analysis Service SCAS Ltd. | Terada K.,Sumika Chemical Analysis Service SCAS Ltd. | Suehiro S.,Sumika Chemical Analysis Service SCAS Ltd.
Electrochemistry | Year: 2015

A novel in situ Raman imaging technique has been developed to visualize the Li-ion battery reaction during the charge/discharge operation. A specially designed cell enables to measure Raman spectra at high speed so that the in situ measurements are carried out during the reaction. The distribution of the state of charge in cross-section of LiCoO2 cathode has been visualized as a demonstration. Inhomogeneous state of charge distribution is observed and there are some active materials where Li+ does not completely return after discharging. This technique enables to evaluate not only the electrode performance but also battery degradation, and thus may promote the realization of the next generation batteries. © The Electrochemical Society of Japan, All rights reserved. Source

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