Application of high energy X-ray diffraction and Rietveld refinement in layered lithium transition metal oxide cathode materials

Layered lithium transition metal oxide (LTMO) cathode materials have attracted much attention for lithium-ion batteries and are shining in the current market. Establishing a clear structure–performance relationship is necessary for the performance improvement of LTMO cathode materials. The combination of synchrotron X-ray diffraction (XRD) with high intensity and XRD Rietveld refinement is powerful for revealing the structural characteristics of LTMO cathode materials. This review summarizes the application of high energy XRD and Rietveld refinement in LTMO cathode materials, including the brief introduction of synchrotron XRD and Rietveld refinement and their applications in understanding the structural evolution related to the synthetic, thermal runaway, cycling, and high-rate charge/discharge process of LTMO cathode materials. Synchrotron XRD can provide insights into the intermediates and reaction paths in the synthesis process, the origin of thermal runaway, the mechanism of structural decay during cycles, and the structural evolution during high-rate charging/discharging. Future works should focus on the development of higher intensity X-rays to gain more in-depth insights into the intrinsic relationship between their structural characteristics and properties.