Improving Energy Density and Structural Stability of Manganese Oxide Cathodes for Na-Ion Batteries by Structural Lithium Substitution
Improving Energy Density and Structural Stability of Manganese Oxide Cathodes for Na-Ion Batteries by Structural Lithium Substitution
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DOI：
10.1021/acs.chemmater.6b04078
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发表时间：
2016-12-27
影响因子：
8.6
通讯作者：
Nazar, Linda F.
中科院分区：
文献类型：
--
作者：
de la Llave, Ezequiel;Talaie, Elahe;Nazar, Linda F.
报道了P2 -Na_（0.6）Li_（0.2）Mn_（0.8）O_2的优异循环性能，它是一种理想的钠离子电池正极材料。这种主要含有Mn 4+的材料在第一次充电时表现出长的电压平台，类似于高容量的富锂和富锰金属氧化物。循环电极的电化学测量、X射线衍射和元素分析表明，活化过程包括从材料中提取锂。“活化的”材料在4.6-2.0 V（相对于Na/Na+）之间的电压窗口中100次循环后提供稳定的高比容量，高达190 mAh/g。密度泛函理论计算发现氧原子的能态在费米能级附近，表明氧化物离子对氧化还原过程可能有贡献。与许多先前报道的钠化过渡金属氧化物电极材料相比，向晶格中添加Li通过抑制在循环期间用钠锰氧化物普遍观察到的有害结构转变来改善结构稳定性。本研究展示了基于阳离子和阴离子氧化还原基团的活性插层材料用于钠离子电池技术的前景。
We report excellent cycling performance for P2 - Na0.6Li0.2Mn0.8O2 an auspicious cathode material for sodium-ion batteries. This material, which contains mainly Mn4+ exhibits a long voltage plateau on the first charge, similar to that of high-capacity lithium and manganese-rich metal oxides. Electrochemical measurements, X-ray diffraction, and elemental analysis of the cycled electrodes suggest an activation process that includes the extraction of lithium from the material. The "activated" material delivers a stable, high specific capacity up to similar to 190 mAh/g after 100 cycles in the voltage window between 4.6-2.0 V versus Na/Na+. DFT calculations locate the energy states of oxygen atoms near the Fermi level, suggesting the possible contribution of oxide ions to the redox process. The addition of Li to the lattice improves structural stability compared to many previously reported sodiated transition-metal oxide electrode materials, by inhibiting the detrimental structural transformation ubiquitously observed with sodium manganese oxides during cycling. This research demonstrates the prospect of intercalation materials for Na-ion battery technology that are active based on both cationic and anionic redox moieties.