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.
Aluminum Casing Deflection
Meaning
Structural displacement of a protective prismatic battery shell under internal pressure represents the primary metric for evaluating cell expansion under stress. Over time, aluminum casing deflection arises from the internal forces of electrode swelling during cycling and gas accumulation. This expansion can alter the contact pressure between cells when they are assembled into a pack module.
Structural Boundary
Containment systems in battery packs must counteract the physical swelling that occurs under continuous operational cycles. Excess aluminum casing deflection occurs when the metal is pushed beyond its elastic limit, causing permanent structural alteration that compromises the thermal interface. When the cell cannot maintain its original flat profile, the heat transfer to the cooling plate becomes uneven.
Mechanical Consequence
Cell degradation accelerates when the internal components lose uniform stack pressure due to localized wall movement. In cells experiencing aluminum casing deflection, the distance between the anode and cathode increases locally, which raises the internal ionic resistance and creates areas of uneven current density. This mechanical failure reduces the operating life of the cell and increases the likelihood of localized lithium plating.
The uneven pressure also promotes localized delamination of the active material from the current collector, creating pockets where lithium ions can no longer participate in active cycling.
Measurement Protocol
Precision displacement sensors track the physical change in shell thickness across the wide face of the cell. The evaluation of aluminum casing deflection relies on multi-point laser scans under controlled ambient temperatures.