Elucidation of the Factors That Determine the Reaction Distribution during Charging in Graphite Electrodes for All-Solid-State Batteries Using in Situ Nano X-ray Tomography and Digital Volume Correlation Analysis

The reaction distribution within composite electrodes of all-solid-state batteries is often nonuniform, causing various problems. In this study, we developed an in situ method at the three-dimensional and nanometer scale of the reaction distribution and the morphological changes during the charging process of a graphite composite electrode. The feature of the method presented is that it clarifies the factors that determine the reaction distribution by quantitatively analyzing the reaction distribution and three-dimensional changes that occur during charging at the same time using nanocomputed tomography (nano-CT) and digital volume correlation (DVC) analysis. As a result, it was found that the cracking caused by the expansion of the graphite blocks the ionic conduction pathway, leading to the formation of a more serious reaction distribution. The measurement and analysis methods developed in this study will provide useful information for the design of composite electrodes and the evaluation of electrode materials in the future.