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arXiv 1703.09079cond-mat.mtrl-sci
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氧含量对锂离子电池负极材料低氧化硅结构和电子性质影响的第一性原理研究

A first-principles study on the effect of oxygen content on the structural and electronic properties of silicon suboxide as anode material for Lithium Ion Batteries

Obaidur Rahaman, Bohayra Mortazavi, Timon Rabczuk

摘要:

低价氧化硅因其容量大而被认为是锂离子电池负极材料的唯一候选材料。然而,关于氧含量对其性能的作用,没有足够的信息。为此,我们使用密度泛函理论来创建各种Si:O比的低氧化硅基质,并研究了氧含量对基质的结构、动力学、电子性质和锂化行为的作用。我们的研究表明,O原子与插入的Li原子强烈相互作用,导致基质的解体。我们发现,混合物中较高浓度的氧原子降低了其在锂化时的相对膨胀,这是阳极材料的理想品质。它有助于防止由于体积波动大而产生的裂纹和粉化。我们的研究还表明,较高的氧含量增加了阳极的储锂容量。然而,它也可以导致形成稳定的复合物,如硅酸锂,这可能导致可逆的容量损失,如电压-组成曲线所示。该研究提供了有价值的见解的作用,氧在缓和的作用,锂在硅低氧化物混合物的微观细节。

英文摘要:

Silicon suboxide is currently considered as a unique candidate for lithium ion batteries anode materials due to its considerable capacity. However, no adequate information exist about the role of oxygen content on its performance. To this aim, we used density functional theory to create silicon suboxide matrices of various Si:O ratios and investigated the role of oxygen content on the structural, dynamic, electronic properties and lithiation behavior of the matrices. Our study demonstrates that the O atoms interact strongly with the inserted Li atoms resulting in a disintegration of the host matrix. We found that higher concentration of oxygen atoms in the mixture reduces its relative expansion upon lithiation, which is a desirable quality for anode materials. It helps in preventing crack formation and pulverization due to large fluctuations in volume. Our study also demonstrate that a higher oxygen content increases the lithium storage capacity of the anode. However, it can also cause the formation of stable complexes like lithium silicates that might result into reversible capacity loss as indicated by the voltage-composition curves. The study provides valuable insights into the role of oxygen in moderating the interaction of lithium in silicon suboxide mixture in microscopic details.

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