In‐Situ Characterization of Dynamic Morphological and Phase Changes of Selenium‐doped Germanium Using a Single Particle Cell and Synchrotron Transmission X‐ray Microscopy

Abstract The dynamic information of lithium‐ion battery active materials obtained from coin cell‐based in‐situ characterizations might not represent the properties of the active material itself because many other factors in the cell could have impacts on the cell performance. To address this problem, a single particle cell was developed to perform the in‐situ characterization without the interference of inactive materials in the battery electrode as well as the X‐ray‐induced damage. In this study, the dynamic morphological and phase changes of selenium‐doped germanium (Ge 0.9 Se 0.1 ) at the single particle level were investigated via synchrotron‐based in‐situ transmission X‐ray microscopy. The results demonstrate the good reversibility of Ge 0.9 Se 0.1 at high cycling rate that helps understand its good cycling performance and rate capability. This in‐situ and operando technique based on a single particle battery cell provides an approach to understanding the dynamic electrochemical processes of battery materials during charging and discharging at the particle level.