成果報告書詳細
管理番号20120000000312
タイトル*平成23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に係る軟X線放射光をプローブとする高度解析技術開発 8
公開日2012/7/11
報告書年度2011 - 2011
委託先名学校法人立命館
プロジェクト番号P09012
部署名スマートコミュニティ部
和文要約和文要約等以下本編抜粋:
1. 共同研究の内容及び成果等
立命館大学SRセンターでは、SPring-8 と相補的な軟X線領域を中心にしたX 線吸収分光(XAFS)、光電子分光(PES)を用いた手法の高度化を行っている。平成23 年度は、センターの3 つの既存ビームライン、超軟X線分光(BL-2)、収束軟X線分光(BL-10)、収束硬X線分光(BL-3)ビームラインに、新しく硬X線分光(BL-4)ビームラインを追加して、蓄電池材料研究のための研究環境を整備し、高度解析技術開発を行っている。平成23 年度における研究の内容と成果は以下のとおりである。
(1) 高感度蛍光X 線検出器の導入と深さ分解XAFS 法の実用化
軟X線XAFS法では検出モードを電子収量と蛍光収量法で測定することで、深さ分解局所構造解析が可能になるが、これまで全発光収量法しかなかったため、満足な深さ分解解析ができなかった。今回、受光面積80 mm2、0.1μm 厚有機薄膜の電子遮蔽窓の大口径シリコンドリフト検出器(KETEK 製SDD)を用いた高感度超軟X 線蛍光検出システムを設計製作した(図1参照)。エネルギー分解能は80 eV @525 eV であり(図2 参照)、これまでよりS/B 比が4 桁以上高く、高感度の蛍光X 線収量XAFS 測定ができるようになった。これによって、部分電子収量、全電子収量、蛍光X 線収量の同時測定が可能になり、蓄電池材料の深さ分解評価が大きく進展した。
英文要約Development of innovative analytical methods for secondary batteries using soft X-ray synchrotron radiation

 In the SR center of Ritsumeikan University, four beamlines for X-ray spectroscopies (BL-2, BL-3, BL-4 and BL-10) are devoted to the studies of secondary batteries and several developments and improvements have been performed in the fiscal year, 2011.

(1) Development of a high resolution X-ray fluorescence detector for the depth-profiling XAFS
A new silicon drift detector (SDD) was installed in the XAFS chamber of BL-2. It has a large effective detection area (80 mm2), covered by a thin (0.1 ?m) organic film. The energy width is about 80 eV, which is narrow enough to resolve O-K and Mn-L edges. This SDD has been successfully used as a detector for the partial fluorescence yield XAFS. Signal to background ratio (S/B) has been improved by 4 orders of magnitude compared with the total fluorescence yield mode. Combined the partial fluorescence yield (PFY) mode using this SDD as the detector, with total (partial) electron yield modes, soft XAFS has become a powerful method of depth profiling local structure analysis..

(2) Differential Pumping system at BL-2 for experiments under low vacuum.
In order to measure XAFS spectra of wet samples or those without degassing in the soft X-ray monochromator beamline (BL-2) which should be kept in high vacuum, we have constructed a differential pumping system, which consists of a newly designed post focusing mirror chamber with apertures at both ends. We confirmed that the system enables us to make the pressure difference of 2-3 orders of magnitude between the analyzer chamber and the post focusing chamber.

(3) Development of soft XAFS measurement of liquid samples at BL-10.
We have developed a XAFS measurement system for a sample in liquid state. A liquid sample is installed in a special cell sealed by a kapton film in an Ar gas filled glove box and transferred in a He gas filled XAFS chamber. P and Cl K-XAFS spectra of several electrolyte solutions were successfully obtained in the fluorescence yield mode.

(4) Improvement of an imaging hard XAFS system and its applications at BL-4.
The 1D imaging XAFS system, developed in last fiscal year, was upgraded to the 2 D imaging system at BL-4, which has a detection area of 4.8 mm × 3.6 mm with a spatial resolution of 10 ?m × 10 ?m. This was applied to monitor the discharging and charging processes of a cathode of LiFePO4. Spatial distribution of Fe2+ (charging state) and Fe3+ (charging state) can be easily discriminated from the Fe K-XANES experiment. A distinct non-uniform discharging was observed, though the sample was finely ground to small powders (< 1 ?m?). The results obtained are especially useful for studying spatial distribution of electrochemical reactions in real batteries.
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