Meaning
Compressive forces acting perpendicular to the flat faces of pouch or prismatic cells within a module secure the assembly and maintain internal electrode alignment. During charging and discharging cycles, structural stack pressure prevents the swelling of lithium-ion cells which can lead to rapid degradation or mechanical failure of the holding bracket. Sourcing engineers specify this pressure range to design reliable retention plates and choose appropriate foam compression pads.
This mechanical force balances cell life with the weight of the retention frame.
Cell Compression
Internal pressure rises as lithium ions intercalate into the anode, causing the cell to expand against the module frame. If this expansion occurs without resistance, the active materials can delaminate, which reduces the electrical capacity of the battery. Maintaining the correct structural stack pressure prevents this physical separation.
Mechanical Integrity
Frames must be rigid enough to resist these forces without bending.
Sourcing Impact
Sourcing high-strength aluminum alloys or composite materials for endplates allows modules to withstand the high pressures generated during operation without adding excessive weight to the pack. Sourcing teams compare the yield strength of these materials to ensure that the structural frame does not fail during maximum cell expansion. This decision directly influences the energy density of the pack.
