Structural Modulation in the High Capacity Battery Cathode Material LiFeBO3,Journal of the American Chemical Society

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Structural Modulation in the High Capacity Battery Cathode Material LiFeBO3
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2012-07-17 , DOI: 10.1021/ja301881c
Yuri Janssen ₁ , Derek S. Middlemiss ₂ , Shou-Hang Bo ₁ , Clare P. Grey _{1,

2} , Peter G. Khalifah _{1,

3}

Affiliation

The crystal structure of the promising Li-ion battery cathode material LiFeBO(3) has been redetermined based on the results of single crystal X-ray diffraction data. A commensurate modulation that doubles the periodicity of the lattice in the a-axis direction is observed. When the structure of LiFeBO(3) is refined in the 4-dimensional superspace group C2/c(α0γ)00, with α = 1/2 and γ = 0 and with lattice parameters of a = 5.1681 Å, b = 8.8687 Å, c = 10.1656 Å, and β = 91.514°, all of the disorder present in the prior C2/c structural model is eliminated and a long-range ordering of 1D chains of corner-shared LiO(4) is revealed to occur as a result of cooperative displacements of Li and O atoms in the c-axis direction. Solid-state hybrid density functional theory calculations find that the modulation stabilizes the LiFeBO(3) structure by 1.2 kJ/mol (12 meV/f.u.), and that the modulation disappears after delithiation to form a structurally related FeBO(3) phase. The band gaps of LiFeBO(3) and FeBO(3) are calculated to be 3.5 and 3.3 eV, respectively. Bond valence sum maps have been used to identify and characterize the important Li conduction pathways, and suggest that the activation energies for Li diffusion will be higher in the modulated structure of LiFeBO(3) than in its unmodulated analogue.

中文翻译：

高容量电池正极材料 LiFeBO3 中的结构调制

基于单晶 X 射线衍射数据的结果重新确定了有前途的锂离子电池正极材料 LiFeBO(3) 的晶体结构。观察到使 a 轴方向上的晶格周期加倍的相应调制。当 LiFeBO(3) 的结构在 4 维超空间群 C2/c(α0γ)00 中细化时，α = 1/2 和 γ = 0，晶格参数 a = 5.1681 Å，b = 8.8687 Å， c = 10.1656 Å，β = 91.514°，消除了先前 C2/c 结构模型中存在的所有无序，结果揭示了角共享 LiO(4) 的一维链的长程排序Li和O原子在c轴方向上的协同位移。固态混合密度泛函理论计算发现调制使 LiFeBO(3) 结构稳定 1。2 kJ/mol (12 meV/fu)，并且在脱锂后调制消失，形成结构相关的 FeBO(3) 相。LiFeBO(3) 和 FeBO(3) 的带隙计算分别为 3.5 和 3.3 eV。键价总和图已被用于识别和表征重要的锂传导途径，并表明 LiFeBO(3) 的调制结构中的锂扩散活化能将高于其未调制的类似物。

更新日期：2012-07-17

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