Plasma Treatment Method for Improving Battery Cell Insulation Defects and Secondary Battery Manufacturing Method Comprising the Same

A method for manufacturing a secondary battery comprising:

• moving a pouch sheet in which a metal layer is coated with a polypropylene layer on a moving stage;
• applying an alternating current power source between the moving stage and a plasma head, and discharging gas sprayed from the plasma head to spray the polypropylene layer surface of the pouch sheet with plasma gas;
• forming a pouch case with a battery cell having leads in which a metal layer is coated with a polypropylene layer by molding the plasma surface-treated pouch sheet;
• and
• sealing the pouch case by forming a sealing region through heat fusion, and
• wherein in the pouch sheet, the gas is discharged to the sealing region and a temporary adhesion region near the sealing region.

A secondary battery comprising:

• an upper pouch case having a metal layer and in which a polypropylene coating layer is formed on a lower surface thereof, wherein the polypropylene coating layer is plasma surface-treated;
• a lower pouch case having a metal layer and in which a polypropylene coating layer is formed on an upper surface thereof, wherein the polypropylene coating layer is plasma surface-treated;
• and
• a battery cell having leads having a metal layer and in which polypropylene coating layers are formed on upper and lower surfaces of the leads, and when the upper pouch case and the lower pouch case are sealed by heat fusion, the upper and lower surfaces of the leads are each heat-fused between the upper pouch case and the lower pouch case, and
• wherein in a pouch sheet which forms the upper pouch case or the lower pouch case, plasma surface treatment is performed on a sealing region and a temporary adhesion region near the sealing region.