Prismatic Cell Enclosure Mechanical Stress Distribution under Solid-State Anode Expansion
Prismatic solid-state cell enclosures demand module preloads between 2 and 8 MPa with flexible interlayers to control wall deflection and dendrites.
Plastic Yielding Limits
Meaning
Stress thresholds at which a material transitions from elastic deformation to permanent plastic deformation define the maximum load-bearing capability of battery structural enclosures. Exceeding plastic yielding limits results in irreversible damage to components like casing walls, endplates, and structural braces. These limits must be carefully evaluated to ensure the long-term safety of the pack.
Load Limit
Structural components must be designed to keep their internal stresses well below the point of permanent deformation during normal operation. When the external or internal forces exceed the plastic yielding limits, the component cannot return to its original shape once the load is removed. This change occurs when the mechanical stress exceeds the yield strength.
Structural Failure
Permanent bending or buckling of the module endplates occurs when the swelling forces of the cells exceed the strength of the support structure. When the metal casing or bracket exceeds its plastic yielding limits, the cell losing its uniform compression begins to deform and degrade faster. This structural failure can also cause the cooling plate interface to separate, leading to uneven thermal profiles and accelerated aging of the cells.
In extreme cases, the deformed parts can pinch internal wiring and cause a high-voltage short circuit.
Testing Protocol
Tensile testing of material coupons determines the offset yield strength under standard laboratory conditions. These measured values are used to establish the plastic yielding limits of the alloys.