Method for regenerating cell

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.