Spinel manganese oxide: A high capacity positive electrode material for the sodium ion battery
Spinel manganese oxide: A high capacity positive electrode material for the sodium ion battery
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DOI：
10.1016/j.electacta.2016.07.038
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发表时间：
2016-09
影响因子：
6.6
通讯作者：
R. Kataoka;M. Kitta;Ozaki Hiroyuki;N. Takeichi;T. Kiyobayashi
中科院分区：
文献类型：
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作者：
R. Kataoka;M. Kitta;Ozaki Hiroyuki;N. Takeichi;T. Kiyobayashi
这是首次报道尖晶石型锰氧化物作为钠离子电池的高容量正极材料。通过从单斜层状Li 2 MnO 3中电化学提取Li，我们制备了Li提取区域具有立方尖晶石结构的Li 2 − xMnO 3（x= 1.6-1.8）。Li 2 − xMnO 3相对于Na负极的可逆放电和充电容量最初超过200 mA · h · g−1，表明接近1摩尔当量的Na插入到分子式单元Li 2 − xMnO 3中并从分子式单元Li 2 − xMnO 3中提取。该电极在50次循环后仍保持160 mA · h · g-1的容量。同步X射线衍射（SR-XRD）和透射电子显微镜（TEM）分析表明，Li 2 − xMnO 3的尖晶石结构在Na的插入和拔出过程中保持了其晶体结构，但在Na的插入过程中晶体的周期性明显丧失。SR-XRD曲线的数值模拟表明，插入Na的Li 2 − xMnO 3在保持尖晶石结构的同时，只有一到两个晶胞的周期性。XAS揭示，发现可逆容量由Mn（III）和Mn（IV）之间的氧化还原主导，并且Mn-Mn距离在Na-插入后显著失去其相关性，这与宽SR-XRD曲线一致。
This is the first report about a spinel manganese oxide that serves as a high capacity positive electrode material for the sodium ion battery. By electrochemically extracting Li from a monoclinic layered Li2MnO3, we prepared Li2−xMnO3(x= 1.6-1.8) of which the Li-extracted domain has a cubic spinel structure. The reversible discharge and charge capacity of Li2−xMnO3versus the Na negative electrode initially exceeded 200 mA · h · g−1, suggesting that close to one molar equivalent of Na is inserted in and extracted from the formula unit, Li2−xMnO3. The electrode retains the capacity of 160 mA · h · g−1after 50 cycles. On the other hand, the Li2−xMnO3electrode versus the Li negative electrode significantly degrades upon cycling.Theex-situsynchrotron X-ray diffraction (SR-XRD) and transmission electron microscopy (TEM) analyses revealed that the spinel domain of Li2−xMnO3retains its crystallographic structure during the Na insertion and extraction, although the crystal significantly loses its periodicity when Na is inserted. A numerical simulation of the SR-XRD profile suggests that the Na-inserted Li2−xMnO3has the periodicity of only one to two unit cells while retaining the spinel structure. XAS revealed that the reversible capacity is found to be dominated by the redox between Mn(III) and Mn(IV) and the Mn-Mn distance significantly loses its correlation upon Na-insertion, which is consistent with the broad SR-XRD profile.