Submicron Material Inhomogeneity & Contamination Mapping of NMC Cathode Material

Homogeneity, contamination and trace elements of battery electrode components (i.e. NMC precursors) affect the device performance hence they must be pre-screened. For conclusive energy dispersive X-ray spectroscopy (EDS) elemental analysis, a polished and sample surface is usually ideal, but it cannot always be achieved, especially when the materials must be analyzed in an “as-received" status.

As battery electrode materials exhibit high surface topography, EDS with SEM using conventional EDS detector geometry can be challenging for such specimen. Furthermore, materials with low electrical conductivity or high electron beam sensitivity can only be investigated using low beam currents, which in turn results in a low X-ray signal. Under these conditions, trace elements cannot be analyzed with conventional EDS in reasonable measurement times.

The  XFlash^® FlatQUAD EDS detector overcomes these limitations and provides datasets within minutes.

The distribution of NMC powder contaminants is identified at the submicron scale, beyond the qualitative net intensity mapping (Fig. 1). This is achieved with the AUTOPHASE algorithm of ESPRIT software, that calculates area fractions of the identified contaminant phases (Fig. 2).

The inhomogeneous distribution of the main component (Co) is visualized by net intensity map (Fig. 3). Local concentration differences (local enrichment of Co) are confirmed by quantification of extracted spectra