Pietsch Patrick, Westhoff Daniel, Feinauer Julian, Eller Jens, Marone Federica, Stampanoni Marco, Schmidt Volker, Wood Vanessa
Laboratory of Nanoelectronics, Department of Information Technology and Electrical Engineering, Gloriastrasse 35, ETH Zurich, 8092 Zurich, Switzerland.
Institute of Stochastics, Helmholtzstrasse 18, Ulm University, 89069 Ulm, Germany.
Nat Commun. 2016 Sep 27;7:12909. doi: 10.1038/ncomms12909.
Despite numerous studies presenting advances in tomographic imaging and analysis of lithium ion batteries, graphite-based anodes have received little attention. Weak X-ray attenuation of graphite and, as a result, poor contrast between graphite and the other carbon-based components in an electrode pore space renders data analysis challenging. Here we demonstrate operando tomography of weakly attenuating electrodes during electrochemical (de)lithiation. We use propagation-based phase contrast tomography to facilitate the differentiation between weakly attenuating materials and apply digital volume correlation to capture the dynamics of the electrodes during operation. After validating that we can quantify the local electrochemical activity and microstructural changes throughout graphite electrodes, we apply our technique to graphite-silicon composite electrodes. We show that microstructural changes that occur during (de)lithiation of a pure graphite electrode are of the same order of magnitude as spatial inhomogeneities within it, while strain in composite electrodes is locally pronounced and introduces significant microstructural changes.
尽管众多研究展示了锂离子电池断层成像和分析方面的进展，但基于石墨的负极却很少受到关注。石墨的X射线衰减较弱，因此在电极孔隙空间中，石墨与其他碳基成分之间的对比度较差，这使得数据分析具有挑战性。在此，我们展示了在电化学（脱）锂过程中对弱衰减电极进行的原位断层成像。我们使用基于传播的相衬断层成像来促进对弱衰减材料的区分，并应用数字体积相关技术来捕捉电极在运行过程中的动态变化。在验证了我们能够量化整个石墨电极的局部电化学活性和微观结构变化之后，我们将该技术应用于石墨-硅复合电极。我们表明，纯石墨电极在（脱）锂过程中发生的微观结构变化与其中的空间不均匀性处于同一数量级，而复合电极中的应变在局部较为明显，并会引发显著的微观结构变化。
