Swelling Containment

Pressure Control

Batteries expand reversibly during each charge cycle due to ion intercalation and irreversibly over their life due to chemical degradation. The containment system must allow a controlled amount of expansion to prevent excessive pressure from building up on the cells. This control is achieved by using compressible foams that deform under load, maintaining the pressure within the optimal window.

Sourcing teams evaluate the force-deflection curves of different foam materials to ensure they can manage the swelling forces, protecting the cells from premature mechanical fatigue.

Degradation Impact

Inadequate pressure can lead to cell delamination, which increases internal resistance and causes localized lithium plating. Conversely, excessive pressure can deform the cell casing and cause internal short circuits. Sourcing high-quality containment materials ensures that the pressure remains within the safe operating limits throughout the battery’s life.

Such containment is required for achieving the required cycle life and preventing premature capacity loss.

Design Integration

Integrated design solutions incorporate the containment structures into the cell module or pack housing to reduce parts count and weight. The module end plates must be designed to withstand the maximum swelling force without deforming. Sourcing specifications for these end plates define the allowable deflection under peak load.

Strategic integration helps optimize the energy density of the pack while ensuring mechanical safety.