## 3 Results and Discussions
### Compression Cylinder Results  
The same approach of analyzing the results was used for the compression cylinder load-displacement curves evaluation.  
In the V1 configuration, as shown in Figure 11a, the initial stiffness was measured at 0.42 kN/mm without the use of spacers. Upon introducing aluminum spacers, the pack's stiffness surged by 571%, indicating a significant enhancement in its resistance to  
Figure 10: Compression plate, cell configuration V3, center-cut deformation for different spacer’s material: (**a**) aluminum; (**b**) printed PLA; (**c**) printed PLA at 60 \({}^{\circ}\)C.  
Figure 9: Compression plate, cell configuration V2, center-cut deformation for different spacer’s material: (**a**) aluminum; (**b**) printed PLA; (**c**) printed PLA at 60 \({}^{\circ}\)C.  
deformation. The PLA spacers led to an increase of 396% in stiffness. However, this gain was slightly diminished by 21% due to PLA's sensitivity to temperature.  
For the V2 configuration, depicted in Figure 11b, the base stiffness was recorded at 1.75 kN/mm without spacers. The addition of spacers once again resulted in a marked increase in stiffness, though the effects varied slightly compared to V1. Aluminum spacers boosted the stiffness by 425%, showing a strong enhancement. Meanwhile, the PLA spacers provided a 295% increase, but this improvement was only reduced by 33% due to the material's susceptibility to temperature effects in this configuration.  
In the V3 configuration, illustrated in Figure 11c, the stiffness without spacers was 1.33 kN/mm. With the introduction of aluminum spacers, there was a 219% increase in stiffness, demonstrating the spacers' consistent effectiveness across different configurations. The PLA spacers resulted in an 187% increase in stiffness; however, this benefit was reduced by 9% because of PLA's temperature sensitivity.  
This approach is similarly applied to the cylinder compression. In V1, Figure 12, the compression stops at 4 mm for all the materials spacers, which is even more conservative compared to the plate compression setup. In V2, Figure 13, the aluminum spacers compress to 4 mm, the PLA to 5 mm, and the 60 \({}^{\circ}\)C PLA to 7 mm. These values indicate a slight increase in compression for the PLA and 60 \({}^{\circ}\)C PLA compared to the baseline but still well within the safe range. In V3, Figure 14, the compression increases further, with the aluminum at 7 mm, the PLA at 8 mm, and the 60 \({}^{\circ}\)C PLA at 8.5 mm. Although this represents a more aggressive pressing approach compared to V1 and V2, the deformations remain far below the critical 12 mm threshold, thus decreasing the risk of thermal runaway. Across all the configurations, the cells maintain their round shapes when using the spacers.  
Figure 11: Compression cylinder load–displacement curve for different cells configurations: (**a**) V1; (**b**) V2; (**c**) V3.  
Figure 12: Compression cylinder, cell configuration V1, center-cut deformation for different spacer materials: (**a**) aluminum; (**b**) printed PLA; (**c**) printed PLA at 60 \({}^{\circ}\)C.  
Figure 13: Compression cylinder, cell configuration V2, center-cut deformation for different spacer materials: (**a**) aluminum; (**b**) printed PLA; (**c**) printed PLA at 60 \({}^{\circ}\)C.