Method for regenerating cell

1. A method for regenerating a cell having an electrode assembly, in which electrodes and a separator are alternately combined with each other, an electrolyte, and a battery case accommodating the electrode assembly and the electrolyte, the electrolyte in the battery case includes electrolyte disposed outside the electrode assembly and electrolyte disposed inside the electrode assembly, the method comprising: performing a negative pressure processing process in which a negative pressure is applied externally to the battery case to allow a gas disposed between the electrodes to move outside the electrode assembly; performing an ultrasonic wave processing process in which the cell is stimulated by ultrasonic waves to allow the electrolyte disposed outside the electrode assembly to move between the electrodes; and

after performing the ultrasonic wave processing process, performing a positive and negative pressure processing process in which a positive pressure and the negative pressure are repeatedly applied to the cell to allow the electrolyte disposed outside the electrode assembly to move between the electrodes.

2. The method of claim 1 , further comprising, before performing the negative pressure processing process, performing an overcharging process in which the cell is overcharged to allow the electrolyte adjacent to the electrodes to generate the gas through side reaction of the electrolyte, and, as a concentration of the electrolyte disposed inside the electrode assembly is reduced, the electrolyte disposed outside the electrode assembly moves to the inside of the electrode assembly by an osmotic pressure.

3. The method of claim 2 , wherein, in the overcharging process, a voltage of 4.3 V or more is applied to the cell to overcharge the cell.

4. The method of claim 3 , wherein, in the overcharging process, a voltage of 4.3 V to 4.5 V is applied to the cell to overcharge the cell.

5. The method of claim 2 , wherein, in the overcharging process, the cell is overcharged for 0.1 seconds to 1 second.

6. A method for regenerating a cell having an electrode assembly, in which electrodes and a separator are alternately combined with each other, an electrolyte, and a battery case accommodating the electrode assembly and the electrolyte, the electrolyte in the battery case includes electrolyte disposed outside the electrode assembly and electrolyte disposed inside the electrode assembly, the method comprising:

performing a negative pressure processing process in which a negative pressure is applied externally to the battery case to allow a gas disposed between the electrodes to move outside the electrode assembly;

performing an ultrasonic wave processing process in which the cell is stimulated by ultrasonic waves to allow the electrolyte disposed outside the electrode assembly to move between the electrodes; and

after performing the ultrasonic wave processing process, performing a positive and negative pressure processing process in which a positive pressure and the negative pressure are repeatedly applied to the cell to allow the electrolyte disposed outside the electrode assembly to move between the electrodes,

wherein, in the positive and negative pressure processing process, after accommodating the cell in a chamber, the positive pressure is applied to the cell by making an inside of the chamber into a positive pressure state, and the negative pressure is applied to the cell by making the inside of the chamber into a negative pressure state.

7. The method of claim 1 , wherein, in the positive and negative pressure processing process, when the positive pressure is applied to the cell, stimulating the cell by the ultrasonic waves.

8. The method of claim 1 , wherein, in the negative pressure processing process, after accommodating the cell in a chamber, applying a vacuum to an inside of the chamber to apply the negative pressure to the cell.

9. The method of claim 8 , wherein, in the negative pressure processing process, the inside of the chamber becomes a pressure state of −90 kPa to −100 kPa.

10. The method of claim 1 , wherein, in the ultrasonic wave processing process, after immersing the cell in an insulation liquid, the cell is stimulated by ultrasonic waves.

11. The method of claim 10 , wherein the insulation liquid comprises ethanol.

12. The method of claim 11 , wherein the cell comprises an electrode lead electrically connected to the electrode assembly so that a portion of the electrode lead protrudes outside of the battery case, and

in the ultrasonic wave processing process, sealing the electrode lead with an insulation tape, and immersing the cell in a bath in which ethanol is accommodated.

13. The method of claim 1 , wherein, in the ultrasonic wave processing process, ultrasonic waves of 20 kHz to 30 kHz are applied to the cell.

14. The method of claim 1 , wherein, in the ultrasonic wave processing process, when the cell is stimulated by the ultrasonic waves, applying a positive pressure to the cell.

15. The method of claim 3 , wherein, in the overcharging process, the cell is overcharged for 0.1 seconds to 1 second.

16. The method according to claim 2 , wherein the ultrasonic wave processing process is performed by at least one ultrasonic generator disposed outside the battery case.

17. The method according to claim 6 , wherein the ultrasonic wave processing process is performed by at least one ultrasonic generator disposed outside the battery case.

18. The method according to claim 6 , further comprising, before performing the negative pressure processing process, performing an overcharging process in which the cell is overcharged to allow the electrolyte adjacent to the electrodes to generate the gas through side reaction of the electrolyte, and, as a concentration of the electrolyte disposed inside the electrode assembly is reduced, the electrolyte disposed outside the electrode assembly moves to the inside of the electrode assembly by an osmotic pressure.