Jig pressing-type pressing short-circuiting inspection method
A jig pressing-type pressing short-circuiting inspection method includes the steps of: pre-aging battery cells, each of which is manufactured by inserting an electrode assembly in a battery container, injecting an electrolyte into the battery container, and sealing the battery container. The method includes inserting the plurality of battery cells in an active jig; pressing the active jig; and inspecting electric current of the battery cells. The inspection method permits detection of a low-voltage defect of a battery cell in a pre-aging state, which shows a high voltage regulation per capacity, thus greatly reducing the inspection time, and enabling simultaneous inspection of a plurality of battery cells. In addition, a micro-defect occurring in a stack-folding type battery cell can be accurately detected, which is difficult to be detected by the conventional inspection method.
1. A method for detecting a short circuit, the method comprising:
preparing a plurality of battery cells, each battery cell including an electrode assembly in which a positive electrode and a negative electrode are stacked in a battery container with a separator interposed therebetween and an electrolyte, wherein the battery container is sealed;
pre-aging the plurality of battery cells,
after pre-aging the plurality of battery cells, providing the plurality of battery cells in an activation jig;
pressing the activation jig; and
inspecting a current of the battery cells.
2. The method of claim 1 , wherein the method is performed before a first formation process.
3. The method of claim 1 , further comprising: measuring an open circuit voltage (OCV) of the battery cell before, during or after pressing the activation jig.
4. The method of claim 1 , wherein inspecting the current of the battery cells comprises:
applying a constant voltage to the battery cell; and
detecting a separator defect by measuring a leakage current.
5. The method of claim 4 , wherein a range of the applied voltage is from an open circuit voltage of the battery cell to the open circuit voltage of the battery cell+500 μV.
6. The method of claim 5 , wherein the range of the applied voltage is from the open circuit voltage of the battery cell to the open circuit voltage of the battery cell+50 μV.
7. The method of claim 4 , wherein detecting the separator defect includes measuring the leakage current for 2 to 10 seconds.
8. The method of claim 7 , wherein it is determined that there is a separator defect when an average value of the measured leakage current exceeds 0.08 mA.
9. The method of claim 8 , wherein the separator defect includes a tearing, a folding or a puncture of the separator.
10. The method of claim 9 , wherein an area of the tearing of the separator is greater than 0 mm 2 and less than 26.0 mm 2 .
11. The method of claim 9 , wherein an area of the tearing of the separator is greater than 2.0 mm 2 and less than 4.5 mm 2 .
12. The method of claim 1 , wherein a state of charge (SOC) of the battery cell to be inspected is 10% or less.
13. The method of claim 1 , wherein, in pressing the activation jig, the pressing force is between 1 MPa to 5 MPa.
14. The method of claim 1 , wherein, in pressing the activation jig, the pressing force is between 2.83 MPa to 3.34 MPa.
15. The method of claim 1 , wherein the pressing the activation jig includes pressing the battery cell by a pressure pad attached to the activation jig.
16. The method of claim 15 , wherein a portion where the pressure pad contacts the battery cell is an edge portion of a body part of the battery cell.