## 3 Results and Discussions  
### Compression Plate Results  
In the evaluation of the simulation results, key parameters such as stiffness derived from the load-displacement curves and the deformation of the cells were carefully analyzed. The assessment was divided based on the type of loading applied and the specific cell configuration used. For the compression loading scenario involving the flat plate, the influence of the spacers proved significant. The presence of spacers generally resulted in a marked increase in the overall stiffness of the battery pack, alongside a noticeable reduction in cell deformation. For the load-displacement evaluation, the total stiffness was analyzed at 12 mm compression displacement. At this value, in the V2 and V3 configurations, the radial compression of the cells exceeded 4 mm, marking the onset of the densification stage. At this point, the internal structure of the cells becomes significantly compacted, resulting in a  
Figure 5: Cell pack compression experiment: (**a**) no spacers; (**b**) printed spacers. Figure 6: Compression force-displacement validation curves. complete loss of functionality. Furthermore, this degree of deformation poses a substantial risk of thermal runaway due to the heightened likelihood of internal short circuits, as seen in the literature [29; 30]. This value approach is a straightforward comparison of stiffness across different configurations, highlighting the impact of various spacer materials on the structural integrity of the battery pack. The force-displacement behavior observed in the compression of a single cell [13] is also reflected in the compression response of the entire cell pack. However, the specific arrangement of the cells and the sequential deformation of different cell rows influence the overall curve profile. In a pack configuration, the elastic zone appears more insignificant, while the plastic force plateau and densification zones are more noticeable. When spacers are introduced, the force plateau is reduced, and the curves exhibit a more linear increase in force until densification. This indicates that the spacers enhance load distribution and structural support, leading to a more uniform and predictable deformation response in the battery pack. In the V1 configuration, Figure 7a, the base stiffness value was observed at 0.833 kN/mm without any spacers. When aluminum spacers were introduced, the stiffness of the pack increased by 400%, demonstrating a substantial improvement in resistance to deformation. The PLA spacers resulted in an stiffness increase of 360%. However, the PLA stiffness increase was reduced by 12.5% at 60 \({}^{\circ}\)C, the normal battery working temperature. For the V2 configuration, Figure 7b, the stiffness value without spacers was 5 kN/mm. The introduction of spacers again led to a significant enhancement in stiffness, though the results varied slightly from V1. The aluminum spacers increased the stiffness by 363.3%, reflecting a robust improvement. PLA spacers showed a 308.3% increase in stiffness, but, even more than in V1, a temperature-induced reduction was observed, with the stiffness dropping by 29.7% for the PLA spacers. Figure 7: Compression plate load–displacement curve for different cells configurations: (**a**) V1; (**b**) V2; (**c**) V3. In the V3 configuration, Figure 7c, the stiffness without spacers reached 3.75 kN/mm, and the aluminum spacers contributed to a 193% improvement, maintaining their effectiveness across different setups. The PLA spacers provided a 192% increase in stiffness. However, this increase was tempered by an 11% reduction due to the temperature effect on the PLA. For the deformation analysis, the comparison is conducted between the baseline configuration (without spacers) and each alternative configuration. The baseline represents the maximum load at a 12 mm displacement, which is identified as the critical and dangerous deformation level for the pack.