Meaning
Release of dissolved or trapped gases and volatile compounds from solid materials when subjected to a vacuum environment must be managed during the manufacturing of high-performance battery cells. This process, known as vacuum outgassing, occurs during the high-temperature drying of electrodes and separators before electrolyte filling. It prevents the formation of internal voids and gas bubbles that would otherwise degrade the performance of the completed cell.
Removal Mechanism
Trapped moisture, solvents, and atmospheric gases diffuse to the surface of the polymer separator and the active material slurry under deep vacuum. If these species are not removed before the cell is sealed, they react with the electrolyte to create hydrofluoric acid and gas. This outgassing rate depends on the drying temperature and the thickness of the electrode sheets, with denser coatings requiring longer drying times.
Sourcing Strategy
Sourcing contracts for vacuum insulation panels and cell casing polymers specify maximum outgassing rates to ensure long-term vacuum stability. Materials that outgas heavily over time will destroy the vacuum, reducing the thermal performance of the insulation panels. Buyers use standardized thermal outgassing tests to select polymer grades that remain stable over a ten-year battery pack lifetime.
Process Temperature
Excessive thermal loads used to accelerate the drying cycle can degrade polymer binders or melt separator membranes if they exceed material thresholds. Drying temperatures must be kept below the melting point of the separator to avoid cell shorts.
