Method of manufacturing secondary battery

1 . 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%.

2 . 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 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%.

3 . The method of claim 2 , wherein the first charging is performed by charging the electrode assembly so that a state of charge of the electrode assembly is greater than or equal to 40%.

4 . The method of claim 2 , wherein the first charging is performed while pressing the impregnated electrode assembly.

5 . The method of claim 2 , wherein the first charging is performed while pressing the impregnated electrode assembly with a pressure ranging from 0.2 kgf/cm 2 to 10 kgf/cm 2 .

6 . The method of claim 2 , wherein a state of charge of the electrode assembly is not increased between the removing gas and the discharging.

7 . The method of claim 2 , wherein the impregnation is performed 15° C. to 30° C. for 12 hours to 100 hours.

8 . The method of claim 2 , further comprising standing the discharged electrode assembly.

9 . The method of claim 8 , wherein the standing is performed for a time ranging from 12 hours to 60 hours.

10 . The method of claim 2 , further comprising performing an additional discharging of the discharged electrode assembly following the second charging.

11 . The method of claim 2 , wherein the negative electrode comprises a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector, wherein the negative electrode active material layer comprises a negative electrode active material, and

the negative electrode active material comprises at least one selected from a carbon-based active material and a silicon-based active material.

12 . The method of claim 2 , wherein a state of charge of the discharged electrode is 10% or less after the discharging.

13 . The method of claim 2 , wherein a state of charge of the discharged electrode is 0% after the discharging.