Method of manufacturing secondary battery

A method of manufacturing a secondary battery, the method comprising:

• manufacturing a pre-lithiation cell comprising a negative electrode and a lithium metal counter electrode, and pre-lithiating the negative electrode by charging the pre-lithiation cell to produce a pre-lithiated negative electrode;
• separating the pre-lithiated negative electrode from the pre-lithiation cell and manufacturing an electrode assembly comprising the pre-lithiated negative electrode and a positive electrode;
• impregnating the electrode assembly with an electrolyte;
• activating the impregnated electrode assembly by performing a first charging on the impregnated electrode assembly;
• removing gas generated in the activation;
• discharging the activated electrode assembly immediately after removing the gas to produce a discharged electrode, wherein a state of charge of the discharged electrode is 30% or less after the discharging;
• and
• performing a second charging on the discharged electrode assembly,
• wherein no additional process is performed between the removing step and the discharging step, and
• wherein the pre-lithiation is performed by charging the pre-lithiation cell so that a state of charge of the pre-lithiation cell following the charging is 5% to 30%.