Structural Dynamics of Energy Storage Materials with Bragg Coherent Diffractive Imaging
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The ability to visualize crystalline defects and lattice distortions at the nanoscale holds profound implications for enhancing performance and guiding the design of functional materials. Bragg coherent diffractive imaging (BCDI), a synchrotron-based X-ray technique, has emerged as a powerful method for mapping three-dimensional lattice displacements within individual nanoparticles. This thesis explores the application of BCDI to investigate the structural dynamics of battery materials under a range of external stimuli. Chapter 1 provides a comprehensive review of BCDI for defect analysis in functional materials. It introduces the physical principles and data reconstruction methods of BCDI, surveys recent advances in its application to battery, catalytic, and electronic systems, and outlines current challenges and future directions for the field. Chapter 2 presents an ex-situ BCDI study of Al-doped LLZO solid electrolytes. By comparing particles with varying doping levels, this work elucidates how Al incorporation influences strain distributions and defect formation. Chapter 3 employs operando BCDI to investigate high-voltage LNMO cathodes during electrochemical cycling. This study captures the nucleation and growth of a discontinuous phase transformation in a single cathode nanoparticle, demonstrating BCDI’s capability to resolve nanoscale phase evolution under realistic operating conditions. Chapter 4 applies in-situ heating BCDI to compare the microstructural thermal stability of two technologically relevant materials: NMC811 cathode and cubic-phase LLZO electrolyte. The results reveal contrasting defect-annealing behavior and lattice relaxation mechanisms between the two chemistries. Together, these studies establish BCDI as a versatile and sensitive probe of buried nanoscale defects in energy storage materials. By applying BCDI across diverse chemistries and stimuli, this thesis provides fundamental insights into the local structural dynamics of energy materials, informing the design of safer and more durable energy storage systems.