Abstract
Bragg coherent X-ray diffraction imaging has become valuable for visualization of the structural, morphological and strain evolution of crystals in operando electrode materials. As the electrode material particles (either in a single-crystal form or an aggregation form of single crystals) are evenly dispersed and randomly oriented in the electrode laminate, the submicrometer-sized coherentX-ray beam can be used to probe the local properties of electrode material crystals using two approaches. Coherent multi-crystal diffraction provides collective structural information of phase transitions in tens of crystals simultaneously as well as the individual behavior from single crystals, which are oriented at the Bragg condition in the X-ray illumination volume. Bragg coherent diffractive imaging enables one to monitor the evolution of the morphology and strain in individual crystals. This work explores and highlights the Bragg coherent X-ray diffraction measurements of battery electrode materials in operando conditions at the 34-ID-C beamline at the Advanced Photon Source. The experiment is demonstrated with NaNi1/3Fe1/3Mn1/3O2, a sodium-ion cathode material loaded in a half cell. The paper will discuss, in detail, the beamline setup, sample mounting and handling, alignment strategies and the data acquisition protocols.
Highlights
The phase retrieval of diffraction with oversampling strategies was introduced by Sayre in 1952 (Sayre, 1952), though several decades would pass before coherent diffractive imaging (CDI) would be demonstrated with X-rays on a fabricated test pattern (Miao et al, 1999)
The ideal sample for Bragg coherent diffractive imaging (BCDI) measurements is perfect prismatic-shaped crystals with low strain in their pristine state, so that when strain is induced during the electrochemical reaction it can be observed as a significant phase shift introduced by the strain of the lattice (Ulvestad, Singer et al, 2014)
We describe CXD measurements of battery materials in operando conditions at the 34-ID-C Advance Photon Source (APS) beamline
Summary
The phase retrieval of diffraction with oversampling strategies was introduced by Sayre in 1952 (Sayre, 1952), though several decades would pass before coherent diffractive imaging (CDI) would be demonstrated with X-rays on a fabricated test pattern (Miao et al, 1999). Due to the penetration power of X-rays, BCDI allows one to probe 3D strain infor- Statistical structural information Both semi-statistical and individual structural information Morphological and strain information of a single crystal mation non-destructively in operando materials with little specific sample preparation required. The white-beam Laue scanning microscope (Larson et al, 2002) and the threedimensional X-ray diffraction microscope (Schmidt et al, 2004) have demonstrated the capabilities of strain imaging, though the spatial resolution of these methods has not yet reached below the size of typical battery cathode particles. With just tens of crystals giving signal to the measured diffraction pattern one can gain semi-statistical information on the behaviors of the cathode crystals and low-resolution information on the response of individual crystals to (dis)charge cycles This technique fills in the capability gap between conventional XRD and BCDI. This work serves as a general guide for future CMCD and BCDI experiments on electrode materials in operando conditions
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