Defect Formation Energy in Spinel LiNi0.5Mn1.5O4-δ Using Ab Initio DFT Calculations
Defect Formation Energy in Spinel LiNi0.5Mn1.5O4-δ Using Ab Initio DFT Calculations
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DOI：
10.1021/acs.jpcc.5b01661
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发表时间：
2015-04
影响因子：
3.7
通讯作者：
Hiromasa Shiiba;N. Zettsu;M. Nakayama;S. Oishi;Katsuya Teshima
中科院分区：
文献类型：
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作者：
Hiromasa Shiiba;N. Zettsu;M. Nakayama;S. Oishi;Katsuya Teshima
采用从头算密度泛函理论（DFT）计算了Ni/Mn有序P4332和无序Fd3m LiNi0.5Mn1.5O4 （LNMO）中基于氧空位模型和金属过量模型的缺陷形成能。在P4332和Fd3m中，金属过量模型的缺陷形成能均低于氧空位模型。这表明氧空位形成反应不太可能发生，尽管P4332和Fd3m LNMO尖晶石化合物在八面体空位处都发生了间隙阳离子占据。此外，Fd3m中相应的缺陷形成能量低于P4332，说明缺陷的数量对尖晶石框架中阳离子有序/无序的影响较为敏感。这与实验结果一致，表明只有Fd3m倾向于具有氧缺陷。
Defect formation energies based on an oxygen vacancy model and a metal-excess model in Ni/Mn ordered P4332 and disordered Fd3m LiNi0.5Mn1.5O4 (LNMO) were evaluated by using ab initio density functional theory (DFT) calculations. The defect formation energy for the metal excess model was lower than that for the oxygen vacancy model in both P4332 and Fd3m. This indicates that oxygen vacancy formation reactions are unlikely, although interstitial cation occupation at the octahedral vacancies occurred in both P4332 and Fd3m LNMO spinel compounds. In addition, the corresponding defect formation energy in Fd3m was lower than that in P4332, indicating that the amount of defects is sensitive to the cation ordering/disordering in the spinel framework. This agrees with the experimental results that show that only Fd3m tends to possess oxygen defects.