同时进行小角度和广角X射线散射解开的复合电极中的多尺度多相锂化和去离子机理。,ACS Nano

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同时进行小角度和广角X射线散射解开的复合电极中的多尺度多相锂化和去离子机理。
ACS Nano ( IF 15.8 ) Pub Date : 2019-10-08 , DOI: 10.1021/acsnano.9b05055
Christopher L Berhaut ₁ , Diana Zapata Dominguez ₂ , Praveen Kumar ₂ , Pierre-Henri Jouneau ₂ , Willy Porcher ₃ , David Aradilla ₁ , Samuel Tardif ₂ , Stéphanie Pouget ₂ , Sandrine Lyonnard ₁

Affiliation

在锂离子满电池中，在几种电流速率（C速率）下以及经过长时间循环后，研究了a-Si / c-FeSi2 /石墨复合负极的（去）锂化过程以及所产生的原子和纳米级形态变化。同时操作同步加速器广角和小角X射线散射（WAXS和SAXS）。WAXS允许探测局部晶体结构。尤其是，通过LixC6布拉格反射观察到的石墨（去）锂化过程的观察，使得可以利用石墨和活性硅的各自容量。同时独立地，通过SAXS获得有关（去）锂化和纳米级形貌（1至60 nm）的硅状态的信息。在锂化期间，对应于a-Si / c-FeSi2畴内特征距离的区域中的SAXS强度增加。在原始电极和老化电极中，在几个充电/放电循环过程中SAXS / WAXS测量的组合提供了a-Si / c-FeSi2依赖于C速率的顺序（去）锂化机理的完整描述。 /石墨阳极。我们的结果表明，在复合电极内，活性硅的体积不会随锂的插入而线性增加，并指出电极形态在适应纳米级硅膨胀方面的重要作用，这种作用在电池老化后仍然是有益的，并且很可能解释了复合材料的优异性能。在原始电极和老化电极中，在多个充电/放电循环过程中，SAXS / WAXS测量的组合提供了a-Si / c-FeSi2依赖于C速率的顺序（去）锂化机理的完整描述。 /石墨阳极。我们的结果表明，在复合电极内，活性硅的体积不会随锂的插入而线性增加，并指出电极形态在适应纳米级硅膨胀方面的重要作用，这种作用在电池老化后仍然是有益的，并且很可能解释了复合材料的优异性能。在原始电极和老化电极中，在多个充电/放电循环过程中，SAXS / WAXS测量的组合提供了a-Si / c-FeSi2依赖于C速率的顺序（去）锂化机理的完整描述。 /石墨阳极。我们的结果表明，在复合电极内，活性硅的体积不会随锂的插入而线性增加，并指出电极形态在适应纳米级硅膨胀方面的重要作用，这种作用在电池老化后仍然是有益的，并且很可能解释了复合材料的优异性能。

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Multiscale Multiphase Lithiation and Delithiation Mechanisms in a Composite Electrode Unraveled by Simultaneous Operando Small-Angle and Wide-Angle X-Ray Scattering.

The (de)lithiation process and resulting atomic and nanoscale morphological changes of an a-Si/c-FeSi2/graphite composite negative electrode are investigated within a Li-ion full cell at several current rates (C-rates) and after prolonged cycling by simultaneous operando synchrotron wide-angle and small-angle X-ray scattering (WAXS and SAXS). WAXS allows the probing of the local crystalline structure. In particular, the observation of the graphite (de)lithiation process, revealed by the LixC6 Bragg reflections, enables access to the respective capacities of both graphite and active silicon. Simultaneously and independently, information on the silicon state of (de)lithiation and nanoscale morphology (1 to 60 nm) is obtained through SAXS. During lithiation, the SAXS intensity in the region corresponding to characteristic distances within the a-Si/c-FeSi2 domains increases. The combination of the SAXS/WAXS measurements over the course of several charge/discharge cycles, in pristine and aged electrodes, provides a complete picture of the C-rate-dependent sequential (de)lithiation mechanism of the a-Si/c-FeSi2/graphite anode. Our results indicate that, within the composite electrode, the active silicon volume does not increase linearly with lithium insertion and point toward the important role of the electrode morphology to accommodate the nanoscale silicon expansion, an effect that remains beneficial after cell aging and most probably explains the excellent performance of the composite material.

更新日期：2019-10-10

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