Effects of synthesis temperature and precursor composition on the crystal structure, morphology, and electrode activity of 1D nanostructured manganese oxides
Effects of synthesis temperature and precursor composition on the crystal structure, morphology, and electrode activity of 1D nanostructured manganese oxides
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DOI：
10.1016/j.jpowsour.2009.11.053
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发表时间：
2010-09
影响因子：
9.2
通讯作者：
Inyoung Kim;S. H. Lee;Hyung-Wook Ha;Tae Woo Kim;Yoonsoo Han;Jin-Kyu Kang;Dong-Ha Lee;Seong‐Ju Hwang
中科院分区：
文献类型：
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作者：
Inyoung Kim;S. H. Lee;Hyung-Wook Ha;Tae Woo Kim;Yoonsoo Han;Jin-Kyu Kang;Dong-Ha Lee;Seong‐Ju Hwang
一维纳米结构锰氧化物是通过前体 LiMn2−xCrxO4 微晶在水热条件下的氧化反应制备的。所得锰氧化物的晶体结构和形貌很大程度上取决于反应条件和前体的化学组成。 α-MnO2纳米线是在120℃下反应制备的，其长径比随着前驱体中Cr含量的增加而减小。在 160–180°C 下用过硫酸根离子处理前驱体，可产生具有较低 Cr 含量的前驱体 LiMn2−xCrxO4 的 β-MnO2 纳米棒和具有较高 Cr 含量的前驱体的 α-MnO2 纳米线。产物对前体中 Cr 含量的结构依赖性与 Cr3+ 离子的高八面体位点稳定能和/或 Cr 取代时 Mn 价态的增加有关。前驱体中Cr含量的增加降低了在160℃制备的锰酸盐的电极性能，但提高了在180℃制备的锰酸盐的电极活性。这一观察结果可以通过水热处理锰酸盐的结构变化和铬替代来解释。我们得出的结论是，使用尖晶石 LiMn2−xCrxO4 作为前驱体提供了一种合成具有定制晶体结构和形态的一维纳米结构锰酸盐的有效方法。
1D nanostructured manganese oxides are prepared by oxidation reaction of precursor LiMn2−xCrxO4microcrystals under hydrothermal condition. The crystal structure and morphology of the obtained manganese oxides are strongly dependent on the reaction condition and the chemical composition of the precursors. The α-MnO2nanowires are prepared by reaction at 120°C, and their aspect ratios decrease with the Cr content in the precursor. Treating precursors with persulfate ions at 160–180°C yields the β-MnO2nanorods for the precursors LiMn2−xCrxO4with lower Cr content and the α-MnO2nanowires for the precursors with higher Cr content. The structure dependence of the products on the Cr content in the precursors is related to the high octahedral site stabilization energy of Cr3+ions and/or to the increase of Mn valence state upon Cr substitution. The increase of Cr content in the precursors degrades the electrode performance for the manganates prepared at 160°C but improves electrode activity for those prepared at 180°C. This observation can be explained by the structural variation and chromium substitution of the hydrothermally treated manganates. We conclude that the use of spinel LiMn2−xCrxO4as precursors provides an effective way to synthesize 1D nanostructured manganate with tailored crystal structure and morphology.