POUCH FILM FOR SECONDARY BATTERY WITH EXCELLENT ROOM TEMPERATURE AND HIGH TEMPERATURE SEALING STRENGTH WHERE SEALANT LAYER YIELD STRENGTH, SEALANT LAYER THICKNESS RATIO AND SEALANT LAYER GLASS TRANSITION TEMPERATURE ARE CONTROLLED, METHOD FOR PREPARING THE POUCH FILM, SECONDARY BATTERY USING THE SAME AND METHOD FOR MANUFACTURING THE SECONDARY BATTERY

• Main Authors: Kim, Yoohan, Han, Hee Sik, Song, Nok Jung, Jang, Jee Eun, Lee, Doohee
• Format: Patent
• Language: English
• Published: 04.07.2024
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

Disclosed is a secondary battery pouch film including a layered structure wherein at least an outer layer, a barrier layer, and a sealant layer are structured in that order, wherein the sealant layer includes an extrusion (EC) layer and a polypropylene (PP) layer below the extrusion (EC) layer, wherein a thickness ratio of the polypropylene (PP) layer to the sealant layer is more than 0.5, wherein an upper yield strength (N/mm2) in an MD direction of the sealant layer is 17.50 to 19.99, and an upper yield strength (N/mm2) in a TD direction thereof is 17.00 to 19.99, wherein a glass transition temperature (Tg) of the sealant layer is −20° C. to −10° C. The pouch film not only has excellent sealing strength at ambient temperature and high temperature, but also has excellent sealing strength maintenance at ambient temperature and especially at high temperature.