## 3 Results and Discussion
### Width, Removal Energy, and Cut Surface of the Compressed Cathode
Remove energy decreases exponentially as scanning speed is increasing for all laser powers. From the laser power of 100 W to 250 W, the remove energy is similar to each other  
Figure 3: Comparison of (**a**) kerf width and (**b**) top width of the compressed cathode. because the remove energy is measured based on the removed volume, as shown in Figure 2. One the other hand, the remove energy with the laser power of 50 W is significantly less than other cases. In this case, only the top width is measurable since only active electrode material is ablated. It is noted that required remove energy depends on interaction time when full cutting occurs. Figure 5 shows SEM images of the compressed cathode cut at the laser power of 250 W. Figure 5a,b show the cathode top view and a cathode cross-section view, respectively. The melting width is not formed as shown in Figure 5a and it is invisible to all cut samples used in this study. Thus, no clearance width can be seen. More interesting characteristics can be observed in Figure 5b. At the scanning speed of 500 mm/s, a gap between the active electrode material and the current collector, which is delamination, is shown. It is inferred that the excessive heat induces a high recoil pressure so that the pressure pushes the active electrode material up and the amount of pressure generated is stronger than the peel strength between the active electrode material and the current collector. Figure 4: Comparison of removal energy for the compressed cathode. Figure 5: SEM images of compressed cathode with the laser power of 250 W: (**a**) Top view, (**b**) Cross-section. From the scanning speed of 1000 mm/s to 2500 mm/s, the thickness of aluminum increases due to the re-solidified aluminum at the bottom of the specimen. The original thickness was 20 um but the thickness became about 23.5 um after the cutting. This may be caused by the aluminum melting and re-solidification so that the aluminum bead is formed. The melted aluminum is not fully removed during the cutting process, but flowed downward and solidified after the cutting process. Moreover, striation is clearly seen in the scanning speed of 1000 mm/s. This is an indication of flow fluctuation during the cutting process and sudden solidification. From all cut samples, the LiFePO\({}_{4}\) in the form of spherical particles are found in the aluminum region. It may be because the LiFePO\({}_{4}\), detached from the active electrode region due to the high pressure and high temperature, is formed during the cutting process. In addition, the detached LiFePO\({}_{4}\) particles are embedded into the molten pool of aluminum. With the laser scanning speed of 500 mm/s to 2500 mm/s, excessively high pressure and high temperature may lead to unstable laser cutting, or excessive cutting, characterized as delamination, re-solidified aluminum beads, striation, and embedded LiFePO\({}_{4}\) particles. The characteristics observed above are clearly seen in Figure 6.  
At the scanning speed of 3000 mm/s, no delamination and aluminum beads were observed while striation marks and embedded spherical particles of LiFePO\({}_{4}\) are still observed. At the scanning speeds between 3500 mm/s and 5000 mm/s, high cut quality, or proper cutting, can be observed. No delamination, no striation, and no aluminum beads were formed while the LiFePO\({}_{4}\) in the form of spherical particles are still observed.