Degassing method for lithium battery cell

A degassing method for lithium battery cell, comprising the following steps:

• a) providing a lithium battery cell comprising a sealed bag, a degassing tube being arranged on an external surface of the sealed bag, an end of the degassing tube communicating with a space in the sealed bag, an electrolyte solution being filled in the sealed bag and a remnant gas being contained in the sealed bag;
• b) providing a negative pressure on the external surface of the sealed bag to inflate the sealed bag and to decompress the sealed bag and a part of the electrolyte solution being thereby vaporized, the remnant gas being separated from the liquid electrolyte solution and mixed with the vaporized electrolyte solution to form a mixed gas;
• c) extracting the mixed gas via the degassing tube, thereby the vaporized electrolyte solution being pressurized to be liquefied in the degassing tube, and the remnant gas meanwhile being discharged via the degassing tube;
• d) injecting the liquid electrolyte solution in the degassing tube back into the sealed bag;
• and
• e) sealing a seal position on the degassing tube, wherein, in the step e, a portion of the degassing tube between the seal position and the sealed bag is remained and the other portion of degassing tube is removed.