(Invited) Interaction and Transformation of Defects during Sodium-Ion Intercalation

Abstract

Non-equilibrium defects often dictate macroscopic functional properties of materials. In energy materials, dislocations and planar defects significantly modify reversibility and kinetics. Nevertheless, transient imperfections briefly appearing during ionic transport have been challenging to capture, limiting understanding of their life cycle and impact. I will present our recent operando x-ray diffraction, x-ray nanoimaging, and resonant x-ray scattering results in sodium-ion intercalation compounds. Three-dimensional coherent x-ray imaging reveals the transformation and self-healing of a metastable domain boundary, glissile dislocation loop, and stacking faults. I will also discuss structure-selective x-ray spectroscopy, which allows us to link the long-range order with redox reactions in layered oxides during intercalation. The presence of high dimensional defects in energy materials observed with operando nanoimaging suggest their abundance and highlights the importance of defect engineering for developing next-generation energy solutions.