Lab-Scale In Situ X-Ray Diffraction Technique for Different Battery Systems: Designs, Applications, and Perspectives

In order to meet the growing demands of electric vehicles and portable devices, the electrochemical performance of rechargeable batteries is required to be further optimized. Above all, it is of vital importance to understand the reaction mechanism of batteries under working states, which requires a direct observation of the complicated reaction process. Thus, in situ X-ray diffraction (XRD) techniques have been employed in the charge and discharge process to realize real-time monitoring and provide on-site information of structural evolutions and phase transitions within electrode materials. In this review, a detailed summary of lab-scale in situ X-ray diffraction techniques is given and compared with in situ synchrotron XRD at the same time. First, four typical in situ reaction mechanisms are presented and their distinctive characteristics are introduced in detail. Second, the practical applications of in situ X-ray diffraction in different battery systems are described with examples after extensive collections. In addition, the design of in situ cells and some noteworthy experimental details in actual testing are also mentioned. Finally, the further development direction of in situ X-ray diffraction techniques is well prospected.