Electronic states in oxidized NaxCoO2 as revealed by X-ray absorption spectroscopy coupled with ab initio calculation
Electronic states in oxidized NaxCoO2 as revealed by X-ray absorption spectroscopy coupled with ab initio calculation
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DOI：
10.1016/j.jpowsour.2018.02.075
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发表时间：
2018-04
影响因子：
9.2
通讯作者：
H. Niwa;K. Higashiyama;Kaoru Amaha;W. Kobayashi;Y. Moritomo
中科院分区：
文献类型：
--
作者：
H. Niwa;K. Higashiyama;Kaoru Amaha;W. Kobayashi;Y. Moritomo
层状钴氧化物是有前途的钠离子二次电池（SIB）正极材料。通过结合O K边周围的X射线吸收光谱（XAS）和ab初始计算，我们研究了不同氧化态的NaxCoO2的电子态，即O3-Na0.91CoO2（CoO2−0.91）和P2-Na0.66CoO2（CoO2−0.66）。前边 (529-536eV) 区域的 O K 边光谱显示 NaxCoO2 氧化后发生显着变化。在 O3-Na0.91CoO2 中，光谱显示 531eV 处的强带（B 带）。在P2-Na0.66CoO2中，B带的光谱权重增加，并且在530eV处出现新的带（A带）。这些光谱变化通过计算的 O3-NaCoO2 和 P2-Na1/2CoO2 的部分态密度 (pDOS) 定性再现。这些结果表明，随着 NaxCoO2 的氧化，电子部分地从 O 2p 态中移出。
Layered cobalt oxides are promising cathode materials for sodium ion secondary batteries (SIBs). By combined study of the X-ray absorption spectroscopy (XAS) around the O K-edge andab initiocalculation, we investigated the electronic state of the NaxCoO2with different oxidization state,i.e, in O3-Na0.91CoO2(CoO2−0.91) and P2-Na0.66CoO2(CoO2−0.66). The O K-edge spectra in the pre-edge (529–536 eV) region shows significant change with oxidization of NaxCoO2. In O3-Na0.91CoO2, the spectra shows an intense band (B band) at 531 eV. In P2-Na0.66CoO2, the spectral weight of the B band increases and a new band (A band) appears at 530 eV. These spectral changes are qualitatively reproduced by the calculated partial density of states (pDOSs) of O3-NaCoO2and P2-Na1/2CoO2. These results indicate that the electrons are partially removed from the O 2pstate with oxidization of NaxCoO2.