40 cell. Compressible fire-resistant pads can be placed between cells, or potting materials can be applied around the vent of a cell. Therefore, if one cell is venting hot gases, any flames will be directed into the void above. Another potential solution is having cells integrated with isolating material foil with low adhesion of 1.0–1.5 MPa, where the dielectric coating provides 10 times more adhesion. A C2C design also has higher requirements on the dielectric coatings and additional requirements on the fire-retardant agent. Gasketing is another consideration that changes with the C2C structure, requiring more stable gaskets and all-around sealing of the chassis. Compression pads can be used to manage the higher levels of vibration in C2C designs. These pads, made of polyurethane or silicone foam with excellent recovery capabilities, allow for compensating tolerances between pouch cells and can accommodate cell swelling. By applying controlled tension to the cells using materials that exhibit stable compression set over the long term, the lifespan of the battery system can be significantly extended. Simultaneously, the compression pads protect against impacts and the damping properties of the foams can reduce vibrations. The damping elements made of polyurethane or silicone foams are used to reduce shocks and vibrations around sensitive components such as battery cells and electronics within the battery pack, to protect and compensate for gaps or tolerances, and ensure proper function over the lifetime of the pads. AI This is a complex design space that is suited to the large AI models currently being developed. AI is at best in its infancy with respect to designing the materials needed to make prototypes faster, but some experts expect tangible progress by around 2027. It is proving difficult for researchers to train AI in terms of material development because the many interacting factors required in such models do not behave linearly. End of life Other key factors relating to the materials used in C2C designs are repairability and ease of end-of-life dismantling. Packs and modules can be extracted more easily for dismantling, whereas an array of cells with an encapsulant is more difficult to work with. Currently, the priority is to keep critical safety components in place, but using several kilogrammes of structural adhesives in a chassis design would not allow for repairability or end-of-life recycling; consequently, debonding is expected to play a much more important role going forward. May/June 2025 | E-Mobility Engineering Cell-to-chassis battery pack (Image courtesy of Du Pont)
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