Foreign particles analysis on a LiNi_xMn_yCo_zO₂ (NMC) cathode material of lithium ion Battery

We used the XGT-9000 to detect and analyze foreign particles on a lithium ion battery material. We made a NMC cathode simulation sample and added Cu particles in the sample as simulated metal foreign particles. Cu particles could be detected from whole mapping by 100 µm ultra high intensity probe (Figure1 (b) Cu). We could also obtain elemental images of Co, Ni, and Mn (Figure1 (b) Co, Ni, Mn), simultaneously.

We carried out small area mapping using 15 µm ultra high intensity probe in 6 min (within red square, Figure 1 (a)). To verify whether the five particles on the mapping image are Cu particles, we carried out point analyses according to the mapping result (①~⑤: Cu particles ⑥: reference). Figure 1 (d) shows that Cu peaks were found in the spectra from ① to ⑤, and no Cu peak was found in the spectrum ⑥.

We used the particle detection function to determine the morphological information of the detected particles (Figure 2). The particle detection function is effective to count the number of foreign particles on a sample, such as lithium ion battery cathode materials. It automatically extracts particles from an image and shows the particle information (number, coordinate, size and aspect ratio of the particles). Aspect ratio is important to know how sharp a foreign particle is. The larger aspect ratio means that the particle shape is like a needle. In lithium ion battery materials, such needle-shaped particles puncture the separator easily and can be a possible root cause of short circuits. The particle detection function saves time and reduces human error for particle analysis.