Meaning
Compressible polymer sheets placed between battery cells absorb mechanical expansion and maintain a stable pressure within the module. An elastomeric cushion deforms under the swelling force of the cells, preventing excessive stress on the module end plates. It also provides thermal insulation between cells to retard thermal runaway propagation.
Compression Behavior
The relationship between force and deflection governs the effectiveness of the cushion. When the cells swell during charging, the elastomeric cushion must compress without bottoming out or becoming completely rigid. This behavior ensures that the clamping pressure remains within the safe operating window of the cells throughout the cycle.
Material Property
High temperature resistance and low compression set are essential characteristics of the chosen polymer. Silicone foams are widely used due to their long-term stability and consistent mechanical performance under cycling. These materials must also meet strict flammability standards to ensure safety.
Thickness Allocation
Designing the module requires calculating the appropriate uncompressed thickness of the cushion. If the elastomeric cushion is too thin, it cannot absorb the full expansion of the cells at high states of charge. Conversely, an overly thick cushion reduces the energy density of the module by occupying valuable space that could otherwise be filled with active cell volume.
This optimization is crucial for balancing life and capacity.
