## 3 Results and Discussion
### Width, Removal Energy, and Cut Surface of the Uncompressed Cathode
At the scanning speed of 2500 mm/s, no delamination or aluminum beads were observed while the striation marks and spherical particles are observed. From the scanning speed of 3500 mm/s to 5000 mm/s, high-quality cut, or proper cutting, can be observed as shown in Figure 10. No delamination, no striation, and no aluminum beads were formed while the LiFePO\({}_{4}\) in the formed of the spherical particle is still observed. This is similar to the results seen in the compressed cathode. Figure 8: Comparison of removal energy for the uncompressed cathode. Figure 9: SEM images of uncompressed cathode with the laser power of 250 W, (**a**) Top view (**b**) Cross-section. Comparison of Compressed and Uncompressed Cathode: Cutting Configuration, Cutting Region, Absorption Rate, Composition Change  
To compare the compressed and uncompressed cathodes, we presented cutting configuration, cutting region, absorption rate, and composition change. Cutting configuration is obtained by observing the kerf and top widths. The cutting region is classified based on previous studies [13; 14]. Absorption rate is measured from the wavelength of 200 nm to 2400 nm. Composition change is measured by SEM and EDX along with cross-section. Figure 11a shows the comparison of kerf width between compressed and uncompressed cathodes with respect to scanning speed with the laser power of 250 W. The width of the laser power of 250 W is chosen because it clearly shows differences between compressed and uncompressed cathodes. The kerf widths of the uncompressed cathode (blue) are narrower than those of compressed cathode. Figure 11b shows the comparison of the top widths with respect to the scanning speed. It is observed that the top widths of the compressed cathode (red) are narrower than the top widths of the uncompressed cathode. According to measured data of the kerf width and top width, a configuration of the cutting is shown in Figure 11c. The difference between the kerf width and top width of the compressed cathode is smaller than the difference between the kerf width and top width of the uncompressed cathode. When compressed, cathodes suffer deformation caused by the change in the average relative position of its atoms and molecules. LiFePO\({}_{4}\) is contracted in volume by compression, and the total volume of the compressed LiFePO\({}_{4}\) is decreased. Therefore, the density per unit volume  
Figure 11: Comparison of (**a**) Kerf width, (**b**) Top width, and (**c**) Cutting configuration with the laser power of 250 W.  
Figure 10: The cross-section of the uncompressed cathode with the scanning speed of 4000 mm/s. of the compressed LiFePO4 is increased. Increasing density increases the energy required for material removal, as described in Equation (5). As a result, compressed cathodes require a higher volume of energy to remove the unit volume. Since higher energy is required for the compressed cathode to fully remove the LiFePO4 and higher density, the ratio of longitudinal heat transfer to transverse heat transfer for the compressed cathode is higher than the ratio for the uncompressed cathode. Therefore, a narrower top width and wider kerf width of the compressed cathode can be obtained. From the manufacturing perspective, the compressed cathode may provide more efficient laser cutting compared to the uncompressed cathode. From the battery performance perspective, the thickness and loading level of the cathode are the key factors to increase the energy of the battery. However, high loading level and increasing thickness can lead to power limitations and poor rate capability. To balance the performance, it is necessary to modify the formulation of slurry. For example to change the ratio of active materials, binder and conductive carbon materials help to improve the lithium-ion diffusion kinetics. Phase change during thermal driven laser cutting may lead to battery performance deterioration. The thermal driven laser cutting may melt the polymer binder.