Fabrication and Evaluation of Aluminum Laminated Film for a Pouch-Type Secondary Battery.

In this study, we intend to find the laminate condition for improvement of the chemical resistance of the aluminum pouch film widely used as the coating material of the secondary battery. Here, we investigated the properties including the initial adhesive strength and electrolyte resistance between the metal film layer aluminum and the sealant layer cast polypropylene (CPP) film. As for the laminating condition, we changed the temperature and line speed and maintained the identical pressure conditions. A roll-to-roll dry laminate coating system was used in surface treatment agent coating, adhesive coating, and film laminate. As for the laminate condition of the surface treated aluminum and CPP film, the initial adhesive strength of the laminated pouch film manufactured with 110 °C temperature and 30 m/min line speed was 1300 gf/15 mm. The adhesive strength of the 85 °C electrolyte resistance measured after being immersed for 7 days was found to be 800 gf/15 mm. The initial adhesive strength of CPP film laminated to aluminum without surface treatment showed 900 gf/15 mm and decreased sharply to 150 gf/15 mm in the electrolyte at 85 °C after an hour. The initial adhesive strength and electrolyte resistance of the aluminum and CPP were measured by using the universal testing machine.