Flexible battery manufacturing method

A method for manufacturing a flexible battery, comprising:

• an injection step of injecting an electrolyte into an opening of an exterior material accommodating an electrode assembly contained therein;
• an impregnation step of impregnating the electrode assembly with the electrolyte through a pressure difference inside the exterior material;
• and
• a sealing step of sealing the opening,
• wherein a pressure increasing/decreasing process is performed in the impregnation step and one cycle thereof comprises the steps of:
• (1) decreasing the pressure inside the exterior material through the injected electrolyte;
• (2) maintaining the decreased pressure for a predetermined period of time;
• and
• (3) restoring the pressure inside the exterior material to 700 torr to 780 torr,
• wherein the pressure increasing/decreasing process is performed four to eight times with a gradient in the decreased pressure, and
• wherein the decreased pressure of the pressure increasing/decreasing process performed in the next turn is performed at a pressure of 40% to 80% of the decreased pressure of the pressure increasing/decreasing process performed in the previous turn.