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成果報告書詳細
管理番号20170000000231
タイトル*平成28年度中間年報 革新型蓄電池実用化促進基盤技術開発(国立大学法人茨城大学)
公開日2017/11/14
報告書年度2016 - 2016
委託先名国立大学法人茨城大学
プロジェクト番号P16001
部署名スマートコミュニティ部
和文要約
英文要約Research & Development Initiative for Scientific Innovation of New Generation Batteries 2 (RISING2); (FY2016-FY2018) FY2016 Annual Report, Ibaraki University, Japan

In many previous researches of chemical reactions in LIBs under operation, X-ray or neutron diffraction has been applied to analyze crystal structure. On the other hand, it is also required to characterize larger scale structure of several tens nanometer. Small-angle neutron scattering (SANS) is a promising method for characterizing the structure scale with such large-scale domain. SANS has already been established at iMATERIA (BL20) beamline of J-PARC-MLF, and we aim for developing the optical system being capable of SANS as well as the conventional wide-angle diffraction to characterize the crystal structure and the large-scale domain of batteries simultaneously.
Since battery is composed of several components such as anode, cathode, and electrolyte, it is necessary to ascertain which component can affect the SANS profiles with battery operation. Therefore, the SANS profiles of the components of LIBs need to be measured separately, especially after discharge and charge.
We carried out the ex-situ SANS experiments for the materials of LIBs. LiCoO2 and graphite were used for a cathode and anode materials, respectively. Charge and discharge operations were carried out at 0.5 C for ex-situ SANS samples. Since the first charge-discharge cycle irregularly exhibited large capacity, the samples after 2 cycles were used. In addition, to examine the deterioration after high-cycle operation, samples after 100 cycle operation were also prepared. Capacity after the 100 cycles decreased by 20% compared to the initial state. The SANS measurement were carried out in a vacuum chamber in iMATERIA beamline. The incident beam was collimated to 10 x 10 mm2. The anode and cathode samples, which were resolved from charged and discharged LIBs, were sealed in SANS sample cells with aluminum windows.
SANS profiles for charged and discharged samples were successfully observed. The SANS intensity of anode (graphite) was higher than that of cathode (LiCoO2). This may originate from the porous microstructure of graphite. In addition, wide-angle diffraction from crystal structure were simultaneously measured with the low-angle detector bank. It should be mentioned that the shift of the diffraction peaks with charge or discharge was observed in an anode and cathode materials. A slight variation of SANS profile was confirmed for the anode materials with charge and discharge operation. However, the reproducibility of this variation needs to be checked. An increase in SANS intensity was also confirmed especially for the anode material after 100 cycle operation. The formation of the heterogeneous structure is suggested with the deterioration of LIBs. More experimental data will be needed to discuss the origin of this heterogeneity.
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