Tracking Lithiation of Si-Based Anodes in Real Time by Total Scattering Computed Tomography

The existing set of characterization tools does not permit a full description of the three-dimensional (3D) structure and operating mechanisms of amorphous, low-scattering alloying active materials in metal-ion batteries. In this article, we describe and demonstrate a new methodology for analysis of this class of materials based on total scattering computed tomography. Using silicon (Si)-based anodes as a testing platform, we can not only visualize the chemical changes taking place in the electrodes during lithiation but also create a 3D mapping of the electrode components including amorphous active and inactive materials. The mapping was used to select a region of interest in the electrode from which the best possible operando pair distribution function (PDF) of the active material could be obtained. Finally, we deployed differential analysis to highlight the small but systematic changes in the PDF during lithiation, revealing subtle structural transformations at the atomic scale.