Manufacturing method of secondary battery

A manufacturing method of a secondary battery comprising

• an electrode assembly having a positive electrode, a negative electrode, and a separator arranged between the positive electrode and the negative electrode, and
• a battery case configured to accommodate the electrode assembly,
• adhesion layers formed on both surfaces of the separator, the manufacturing method comprising:
• an arranging step for arranging the electrode assembly, in which the positive electrode and the separator are adhered by the adhesion layer and in which the negative electrode and the separator are adhered by the adhesion layer, inside the battery case;
• a peeling step for peeling off at least one, among the positive electrode and the negative electrode, and the separator in the electrode assembly;
• a liquid injection step for performing a liquid injection of an electrolyte solution into the battery case after the peeling step;
• and
• a pressurizing step after the peeling step and before the liquid injection step, wherein
• the peeling step includes a heating process for heating the electrode assembly and a first decompressing process for decompressing the inside of the battery case after the heating process,
• the pressurizing step comprises introducing a gas into the battery case, and
• the gas introduced in the battery case during the pressurizing step pressurizes an inside of the battery case at a speed of 5,000 Pa/min or more and 80,000 Pa/min or less.