A compression fixture is a tool or apparatus designed to apply and maintain pressure on a battery cell or stack of cells. In cell R&D compression fixtures are often used for pouch cells to ensure that the layers (anodes, separators, cathodes) remain in close contact and do not swell or separate during cycling. Proper compression can improve the performance and longevity of a cell by ensuring uniform pressure distribution across the cell, thereby maintaining good contact between the cell components. Keeping good contact as the electrodes expand and contract during cycling is necessary to ensure good cell performance.
At NOVONIX, compression fixtures are utilized when testing cells to simulate the pressures found in commercial battery pack enclosures or to investigate the effects of pressure on cell behaviour. By adjusting the force, NOVONIX can study how compression impacts capacity fade, internal resistance, and the occurrence of issues like lithium plating. Their findings might show, for instance, that using anodes with blends of silicon and graphite benefits from higher stack pressure to maintain contact as the silicon expands and contracts during cycling.
