Imaging inter-and intra-particle features in crystalline cathode materials for Li-ion batteries using nano-focused beam techniques at 4th generation synchrotron sources

Abstract

The necessity of mapping crystal defects in battery materials after synthesis is crucial in understanding heterogeneity within a single crystal domain and among particles to develop superior crystal quality materials. Numerous imaging techniques have been developed over the past years to study these materials at the nanoscale. However, most of them use electron beams which demand many hours of sample preparation, and they are incompatible with the investigation of batteries under realistic working conditions. Techniques such as Scanning X-ray Diffraction Imaging (Scanning X-ray Diffraction Microscopy) or Bragg Coherent Diffraction Imaging are increasingly available on the lat-est generation synchrotron sources. Their progressive deployment will allow for a standardized method for imaging crystal lattice imperfections such as lattice tilt and strain in individual particles without any prior sample preparation. In this paper, we exploited Scanning X-ray Diffraction Microscopy to probe the strain variation in single crystals and polycrystalline particles and Bragg Coherent Diffraction Imaging to reconstruct the volume of a single crystal particle. Presented case studies were performed on particles of different active cathode materials (LiNi0.6 Mn0.2 Co0.2 O2, LiNiO2 and LiMn1.5 Ni0.5 O4); however, these techniques can also be employed on other battery components for a more holistic structural understanding of used materials and (de)lithiation dynamics on the microscale.