Chemical State Visualization of Lithium-Ion Battery Materials by X-Ray Ptychographic Coherent Diffraction Imaging

X-ray ptychographic coherent diffraction imaging (PCDI) is one of the most promising tools for visualizing mesoscopic structures with high spatial resolution of the order of 10 nm or less, and when combined with XAFS spectroscopy, information on the local structure and chemical state (e.g., elemental composition, valence, local structure) can be obtained. Here, some demonstrations of the visualization of chemical states of practical cathode active material particles, lithium nickel manganese oxide (LNMO), and Li-rich disordered rocksalt (DRS)-type lithium vanadium oxide at the nano-/mesoscale using X-ray spectroscopy PCDI are presented. Analysis combined with unsupervised learning to classify the several groups in terms of different elemental compositions and chemical states. The described approach may increase the supply of information for nanoscale characterization and promote the design of suitable structural domains to maximize the performance and stability of batteries.