Compression pads are used to manage the dimensional change of the cell during the breathing process and for the gradual permanent swelling that occurs throughout the battery lifetime.
The cell expands during charging and contracts during discharge, this “breathing” is a small change in cell thickness.
The permanent swelling can be such that at end of life a cell can be 10% to 20% thicker — see Cell Mechanics for more on the underlying degradation mechanisms.
LFP Cell Clamping Pressure
The LFP cell clamping pressure is important as it keeps the active layers in contact.
See also: What’s the right stack pressure?, Stack Pressure & Interfacial Resistance for Pack Designers, Cell Electrode Pressure and Expansion, Cell Electrode Pressure