Impurity Analysis for NCM Cathode Material

Introduction

Trace impurities inside cathode active materials affect battery properties and are a factor that causes degradation. Even trace Na and Mg impurities that are difficult to analyze with energy dispersive X-ray fluorescence (EDXRF) can be analyzed with precision using wavelength dispersive X-ray fluorescence (WDXRF). Additionally, with the standardless FP analysis method, it is possible to analyze from ppm levels of light to heavy elements up to 100% without preparing a calibration curve using standard samples.

Composition analysis

• Analysis: Processed materials
• Analysis method: Standardless FP analysis method
• Use: Quality assurance 
• Analyzed materials: Li(Ni_xCo_yMn_z)O₂

Table 1: Standardless FP analysis results for NCM powder samples A to J (ppm)

Figure 1: Fe spectrum based on WDXRF

Conclusion

Na, Mg, Al, Si, Ca, Fe and other impurities were detected. Because Fe and Mn can be separated, it is possible to analyze the peak of trace Fe impurities.

Compared to EDXRF, WDXRF has higher energy resolution and is less prone to being affected by interfering lines, making it possible to obtain high sensitivity even with light elements such as Na and Mg. As such, with WDXRF, highly reliable analysis values can be obtained for a wide range of elements.