Morphology and texture of spheroidized natural and synthetic graphites

The electrochemical performance of mechanically spheroidized natural and synthetic graphite particles is significantly influenced by the type of spheroidization process used and the applied conditions. In order to guarantee a consistent and high material quality, spherical graphite particles have to be carefully benchmarked before use. Three spherical natural graphites and three spheroidized synthetic graphites are characterized using several physical analysis methods. A special focus is laid on the internal morphology and texture, which has been studied by scanning electron microscopy (SEM) – focused ion beam (FIB) cross-sections and tomography. For the spheroidized natural graphites under investigation this method indicates a volume of closed pores in the range of 4–5% and of open pores of 0.5% or less of the total particle volume. With increasing energy impact during the spheroidization process the open porosity increases and the closed porosity decreases.