ABSTRACT
The search for higher performance, improved safety, and lifetime of lithium-ion batteries relies on the understanding of degradation mechanisms. Complementary to methods and studies on primary particles or crystalline structure on bulk materials, here we use spatially correlated ptychographic X-ray computed nanotomography with a 35 nm resolution and scanning X-ray diffraction microscopy with 1 µm resolution to visualize in 3D the hidden morphological and structural degradation processes in individual secondary particles of lithium-rich nickel, cobalt, and manganese oxides. From comparative examination of pristine and cycled particles, we suggest that morphological degradation could have radial dependency and secondary particle size dependency. The same particles were examined to correlate the degradation to crystallinity, which shows surprising core-shell structures. This study reveals the inner 3D structure of the secondary particles while opening up questions on the unexpected crystalline structural distributions, which could offer clues for future studies on this promising cathode material for lithium-ion batteries.
ABSTRACT
In this work we demonstrate that Medium Energy Ion Scattering (MEIS) measurements in combination with Transmission Electron Microscopy (TEM) or Grazing Incidence Small Angle X-Ray Scattering (GISAXS) can provide a complete characterization of nanoparticle (NP) systems embedded into dielectric films. This includes the determination of the nanoparticle characteristics (location, size distribution and number concentration) as well as the depth distribution and concentration of the NP atomic components dispersed in the matrix. Our studies are performed considering a model case system consisting of planar arrangements of Au NPs (size range from 1 to 10 nm) containing three distinct Au concentrations embedded in a SiO2 film.
