DFT and thermodynamics calculations of surface cation release in LiCoO2
DFT and thermodynamics calculations of surface cation release in LiCoO2
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DOI：
10.1016/j.apsusc.2020.145865
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发表时间：
2020-06-15
影响因子：
6.7
通讯作者：
Mason, Sara E.
中科院分区：
文献类型：
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作者：
Abbaspour-Tamijani, Ali;Bennett, Joseph W.;Mason, Sara E.
虽然 LiCoO2 (LCO) 等复杂金属氧化物 (CMO) 目前用于多种电子设备，但其对环境的影响尚不清楚。在这项工作中，我们应用密度泛函理论 (DFT) 和热力学建模来研究 LCO 表面变换。我们对块状 LCO 进行了拉曼研究，并比较了实验和计算结果。 LCO 模型表面的全面振动分析显示，局部表面模式与本体不同，Li 和 OH 表面终端不同。这项研究的核心是计算，以评估 DFT + 热力学方法对计算参数的依赖性，例如交换相关函数和模型几何形状的选择，特别是改变板厚度和超单元尺寸。我们讨论如何使用结果来确定不同 pH 条件下有利的表面阳离子空位形成的上限和下限。该模型预测，在 pH 值为 7 时，高达 16% 的表面 Co 将发生溶解。我们继续讨论这些模型结果与实验溶出研究的关系。我们还推断我们的结果如何提供有用的见解，以指导（重新）设计具有定制离子释放行为的 CMO。
While complex metal oxides (CMOs) such as LiCoO2 (LCO) are currently used in multiple electronic devices, their environmental impacts are not well understood. In this work, we apply density functional theory (DFT) and thermodynamics modeling to study LCO surface transformations. We performed Raman studies on bulk LCO, and compared experimental and computational results. Full vibrational analysis of the model LCO surfaces show localized surface modes that are distinct from bulk, varying in Li and OH surface terminations. Central to this study are calculations to assess the dependence of the DFT + thermodynamics methodology on computational parameters, such as the choice of the exchange-correlation functional, and model geometry, specifically varying slab thickness and supercell dimensions. We discuss how the results can be used to establish upper- and lower-bounds for favorable surface cation vacancy formation under varying pH conditions. The model predicts that at a pH of 7, up to 16% of surface Co will undergo dissolution. We go on to discuss how these model results relate to experimental dissolution studies. We also extrapolate how our results can provide useful insights to guide the (re)design of CMOs with tailored ion release behavior.