成果報告書詳細
管理番号20130000000515
タイトル*平成24年度中間年報 革新型蓄電池先端科学基礎研究事業 革新型蓄電池先端科学基礎研究開発 (7)
公開日2014/2/21
報告書年度2012 - 2012
委託先名国立大学法人東北大学
プロジェクト番号P09012
部署名スマートコミュニティ部
和文要約
英文要約 1) Development of advanced technologies with X-ray synchrotron radiation sources
In order to investigate how charge/discharge reaction progresses in the composite electrode, we developed novel analytical technique with 2-dimentional X-ray absorption spectroscopic technique (2D-XAS). By using this technique, we clarified active and inactive area in the LiCoO2 composite cathode. For making the reaction distribution visually clear, we prepared special composite cathode, in which the mass transportation in the liquid electrolyte was restricted in two-dimension (the laminated cathode). The 2D-XAS measurements were carried out at BL28XU, SPring8, JASRI. Throughout this work, the 2D-XAS technique, which enable us detect how charge/discharge reaction progresses in the composite electrode, could be established. This technique has the special resolution about micrometer size, and such a high resolution should be a considerable advantage for further understanding of the reaction in the composite electrode of batteries. With the use of the high-flux X-ray obtained at BL28XU, SPring8, a relatively high temporal resolution can be also achieved, and we can take one reaction mapping typically within a few minutes. These characteristics of the 2D-XAS are considered advantageous for in-situ measurements.
2) Development of advanced analysis techniques with nuclear magnetic resonance
We have developed new MRI technique which detects a magnetic property of cathode material via 1H nuclear spin. This technique was used to identify the valence changes in the paramagnetic positive electrode of Lithium battery caused due to intercalation and deintercalation of Lithium ions during charge and discharge process respectively.
7Li NMR Imaging of lithium battery was carried out. The challenge in measuring in-situ 7Li NMR imaging in the frequency band of 155 MHz is the reduction of noises. The external noises were removed by proper shielding. To facilitate the speed imaging, all possible efforts have been made to reduce the noise level. This noise reduction process has enabled us to capture 7Li NMR Images with an acquisition time of four minutes and spacial resolution of 3.4 mm.
We have also investigated the diffusion of various species (cation, anion and solvent) of electrolytes in micro/nano porous media. It is necessary to understand the diffusion of ions in a separator for lithium ion battery to design battery with fast charge discharge rate. The electrolyte was wetted on different pore size membrane and diffusion coefficient was measured for all nuclei in the electrolyte. It was observed that the diffusion coefficient decreased with decreasing pore size. The porous membranes wetted by the electrolytes have diffusion coefficient less compared to that of the free liquid electrolyte.
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