Novel cell tab welding performance defect detection structure

Abstract

The utility model discloses a novel electrical core tab welding performance defect detection structure, which comprises a test fixture and an electrical core placed on the test fixture, the electrical core comprises a positive electrode and a negative electrode, the positive electrode and the negative electrode of the electrical core are respectively positioned at two ends of the electrical core, a tester is arranged on one side of the test fixture, and the tester is connected with the test fixture. And the tester is electrically connected with the positive electrode and the negative electrode of the battery cell respectively. According to the utility model, the four-probe alternating-current impedance tester and a low-frequency scanning test method are directly adopted to detect whether the welding performance of the battery cell is poor or not after the battery cell assembly and liquid injection process, so that the generation of defects is greatly reduced.

Description

Technical Field

[0001] This utility model relates to the field of battery cell manufacturing technology, and in particular to a novel battery cell electrode tab welding performance defect detection structure. Background Technology

[0002] After metal tabs and electrode foils are welded into battery cells, serious performance problems such as incomplete welding and internal foil breakage are unavoidable due to the combined effects of welding equipment, parameters, and incoming materials. When such defective battery cells are installed in vehicles, they pose safety risks such as low voltage, inability to charge and discharge normally, lithium plating short circuits, and even fire.

[0003] For anomalies such as poor welding and internal foil breakage, visual inspection is insufficient for identification. Front-end identification primarily relies on destructive testing, which struggles to balance practicality and effectiveness. Consequently, defective cells are typically relegated to later stages for identification. Current technologies mainly rely on charge-discharge testing and IR / OCV testing during formation (later stage) for detection. However, the time from anomaly occurrence to discovery often exceeds several days, significantly compromising timeliness. The continuous accumulation of hidden defective cells can lead to batch defects, severely increasing manual screening costs, financial losses, and yield rate reductions. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a novel structure for detecting defects in the welding performance of battery cell tabs.

[0005] The objective of this utility model is achieved through the following technical solution:

[0006] A novel battery cell tab welding performance defect detection structure includes: a test fixture and a battery cell placed on the test fixture. The test fixture has a receiving groove, and the battery cell is placed horizontally in the receiving groove. The battery cell includes a positive electrode and a negative electrode, which are located at opposite ends of the battery cell. A tester is provided on one side of the test fixture. The tester is a four-probe AC ​​impedance tester, which is electrically connected to the positive and negative electrodes of the battery cell.

[0007] In one embodiment, the depth of the receiving groove is less than the thickness of the battery cell, and the size of the receiving groove is greater than the size of the battery cell.

[0008] In one embodiment, the test fixture is provided with a support on both sides of the receiving groove, and the two supports are respectively arranged corresponding to the positions of the positive and negative terminals of the battery cell, with the positive and negative terminals of the battery cell placed on the two supports respectively.

[0009] In one embodiment, the tester is provided with four probes, which are electrically connected in pairs to the positive and negative terminals of the battery cell, respectively.

[0010] In one embodiment, the tester and the battery cell are provided with four connecting wires for electrical connection. One end of each of the four connecting wires is connected to the tester, and the other end of each of the four connecting wires is provided with a probe. Two of the four connecting wires are connected to the positive terminal of the battery cell through the probe, and the other two connecting wires are connected to the negative terminal of the battery cell through the probe.

[0011] In one embodiment, the connecting cable is a twisted pair.

[0012] In one embodiment, a shielding wire is provided between the positive and negative terminals of the battery cell. The shielding wire is arranged along the length of the battery cell, and one end of the shielding wire is connected to a probe of two connecting wires connected to the positive terminal of the battery cell, while the other end of the shielding wire is connected to a probe of two connecting wires connected to the negative terminal of the battery cell.

[0013] In one embodiment, the shielding wire is arranged in a straight line and is parallel to the battery cell.

[0014] In one embodiment, the tester uses a low-frequency scanning test method for testing.

[0015] In one embodiment, the test fixture has a pad on its support that contacts the positive and negative electrodes of the battery cell.

[0016] Compared with the prior art, the present invention has at least the following advantages:

[0017] This invention discloses a novel battery cell tab welding performance defect detection structure. After the battery cell assembly and electrolyte injection process, a four-probe AC ​​impedance tester and a low-frequency scanning test method are used to detect whether there are welding performance problems in the battery cell. This ensures full inspection of the battery cell without damage, early identification of abnormalities, timely feedback for welding adjustment and optimization, and a significant reduction in defects. Furthermore, this test method can reduce the interference error of other resistors, increase the identification of effective resistance, and ensure that the battery cell impedance test value effectively reflects the internal performance abnormalities of the battery cell. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the embodiments will be briefly described below.

[0019] Figure 1 A schematic diagram of a novel battery cell tab welding performance defect detection structure provided by this utility model.

[0020] Figure descriptions: 10. Test fixture; 11. Receiving slot; 12. Support; 20. Battery cell; 21. Positive electrode; 22. Negative electrode; 30. Tester; 31. Probe; 32. Connecting wire; 40. Shielding wire; 50. Soft pad. Detailed Implementation

[0021] To facilitate understanding of this utility model, a more comprehensive description of this utility model will be given below with reference to the accompanying drawings.

[0022] A novel structure for detecting defects in the welding performance of battery cell tabs, referring to... Figure 1 The test fixture includes a test jig 10 and a battery cell 20 placed on the test jig 10. The battery cell 20 is formed by welding a positive electrode 21 and a negative electrode 22 to an electrode foil and then assembling and injecting electrolyte. The battery cell 20 is placed horizontally on the test jig 10. The battery cell 20 includes a positive electrode 21 and a negative electrode 22, which are located at opposite ends of the battery cell 20. A tester 30 is provided on one side of the test jig 10. The tester 30 is electrically connected to the positive electrode 21 and the negative electrode 22 of the battery cell 20. The tester 30 is directly electrically connected to the battery cell 20 after assembly and electrolyte injection, i.e., in the previous process. This moves the detection of abnormal welding performance forward, allowing for timely identification of abnormalities, elimination of defective battery cells 20, warning of abnormalities, timely adjustment, and reduction of defects, effectively avoiding the risk of accumulating batch abnormalities.

[0023] Furthermore, referring to Figure 1 The test fixture 10 has a receiving groove 11 for accommodating the battery cell 20, which is placed horizontally within the receiving groove 11. It should be noted that the depth of the receiving groove 11 is less than the thickness of the battery cell 20, and the size of the receiving groove 11 is greater than the size of the battery cell 20, to accommodate battery cells 20 of different sizes and specifications. Placing the battery cell 20 horizontally within the receiving groove 11 reduces testing errors caused by electrolyte flow within the battery cell 20.

[0024] Reference Figure 1 The test fixture 10 has two supports 12 on each side of the receiving groove 11. The two supports 12 are respectively positioned to correspond to the positive terminal 21 and negative terminal 22 of the battery cell 20. When the battery cell 20 is placed in the test fixture 10, the positive terminal 21 and negative terminal 22 of the battery cell 20 are placed on the two supports 12 respectively. It should be noted that since the tester 30 needs to be electrically connected to the positive terminal 21 and negative terminal 22 of the battery cell 20, the supports 12 are set to raise the positive terminal 21 and negative terminal 22 of the battery cell 20 to make it more convenient to perform connection tests with the tester 30.

[0025] Reference Figure 1The tester 30 is a four-probe AC ​​impedance tester. It has four probes 31, which are connected in pairs to the positive terminal 21 and negative terminal 22 of the battery cell 20. This structure effectively reduces the influence of wiring resistance, contact resistance, and induced electromotive force. It should be noted that the tester 30 uses a low-frequency scanning test method, which effectively reduces test interference while comprehensively characterizing various impedances of the battery cell 20. The tester 30 uses a frequency less than 10Hz to test the impedance of the battery cell 20 to reflect the combined effects of ohmic internal resistance (Rs), charge transfer impedance (Rct), and concentration impedance (Wo), providing a more detailed and comprehensive characterization of various internal defects within the battery cell 20. Among them, the ohmic resistance (Rs) is the ionic resistance of the electrolyte; the charge transfer resistance (Rct) is the interfacial polarization resistance generated by the transfer of electrons to the interface (this resistance changes accordingly when the foil breaks); the concentration impedance (Wo) is related to the diffusion of alkali metal ions in the electrode material; and the phase constant angle element (CPE) is related to the double-layer capacitance between the electrode and the electrolyte.

[0026] Furthermore, referring to Figure 1 A connection wire 32 for electrical connection is provided between the tester 30 and the battery cell 20. There are four connection wires 32. One end of each connection wire 32 is connected to the tester 30, and the other end of each connection wire 32 is equipped with a probe 31. It should be noted that two of the four connection wires 32 are used to connect to the positive terminal 21 of the battery cell 20, and the other two connection wires 32 are used to connect to the negative terminal 22 of the battery cell 20. By connecting the probes 31 of the four connection wires 32 to the positive terminal 21 and the negative terminal 22 of the battery cell 20 respectively, the tester 30 and the battery cell 20 are electrically connected to achieve impedance testing of the battery cell 20. It should be noted that the connection wires 32 are clearly marked to indicate which two connection wires are used to connect to the positive terminal 21 and which two connection wires are used to connect to the negative terminal 22 of the battery cell 20. For example, the connection wires 32 are red and black, respectively, to indicate that they are used to connect to the positive terminal 21 and the negative terminal 22.

[0027] Furthermore, referring to Figure 1 The connecting cable 32 is a twisted pair cable. Using a twisted pair cable for the connecting cable 32 can reduce electromagnetic induction and effectively reduce test interference.

[0028] Furthermore, referring to Figure 1 A shielding wire 40 is provided between the positive electrode 21 and the negative electrode 22 of the battery cell 20. The shielding wire 40 is arranged along the length of the battery cell 20, and one end of the shielding wire 40 is connected to the probes 31 of the two connecting wires 32 connected to the positive electrode 21 of the battery cell 20, and the other end of the shielding wire 40 is connected to the probes 31 of the two connecting wires 32 connected to the negative electrode 22 of the battery cell 20. The shielding wire 40 can reduce external interference from the tester 30 to the impedance test of the battery cell 20, thereby enhancing the validity of the test results.

[0029] Furthermore, referring to Figure 1 The shielding wire 40 is arranged in a straight line and parallel to the battery cell 20 to reduce external interference. Because a loop is formed between the connecting wire 32 (connected to the positive terminal 21 of the battery cell 20 and the connecting wire 32 (connected to the negative terminal 22 of the battery cell 20) and the battery cell 20, the overlapping portion of the loop exhibits significant electromagnetic induction. Therefore, a shielding wire 40 parallel to the battery cell 20 is connected to the connecting wire 32 to reduce electromagnetic induction.

[0030] Furthermore, referring to Figure 1 The test fixture 10 is made of a non-conductive material to avoid interference with the battery cell 20 during testing. The base 12 of the test fixture 10 is provided with soft pads 50 that contact the positive electrode 21 and negative electrode 22 of the battery cell 20. The soft pads 50 buffer and fix the positive electrode 21 and negative electrode 22 of the battery cell 20 to prevent displacement of the positive electrode 21 and negative electrode 22 of the battery cell 20 due to excessive force when the connecting wire 32 of the tester 30 is connected to the positive electrode 21 and negative electrode 22.

[0031] This invention uses a four-probe AC ​​impedance tester 30 and a low-frequency scanning test method to directly detect whether there are problems with the welding performance of the battery cell 20 after the assembly and liquid injection process. This ensures that the battery cell 20 is fully inspected without damage, and abnormalities are identified in advance. Feedback is provided for timely adjustment and optimization of the welding, which greatly reduces the occurrence of defects. In addition, this test method can reduce the interference error of other resistors, increase the identification of effective resistance, and ensure that the impedance test value of the battery cell 20 effectively reflects the internal performance abnormalities of the battery cell 20.

[0032] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A novel structure for detecting defects in the welding performance of battery cell tabs, characterized in that, include: A test fixture (10) and a battery cell (20) placed on the test fixture (10). The test fixture (10) is provided with a receiving groove (11). The battery cell (20) is placed horizontally in the receiving groove (11). The battery cell (20) includes a positive electrode (21) and a negative electrode (22). The positive electrode (21) and the negative electrode (22) of the battery cell (20) are located at both ends of the battery cell (20). A tester (30) is provided on one side of the test fixture (10). The tester (30) is a four-probe AC ​​impedance tester. The tester (30) is electrically connected to the positive electrode (21) and the negative electrode (22) of the battery cell (20).

2. The novel battery cell tab welding performance defect detection structure according to claim 1, characterized in that, The depth of the receiving groove (11) is less than the thickness of the battery cell (20), and the size of the receiving groove (11) is greater than the size of the battery cell (20).

3. The novel battery cell tab welding performance defect detection structure according to claim 2, characterized in that, The test fixture (10) is provided with a support platform (12) on both sides of the receiving groove (11). The two support platforms (12) are respectively positioned corresponding to the positive electrode (21) and negative electrode (22) of the battery cell (20). The positive electrode (21) and negative electrode (22) of the battery cell (20) are respectively placed on the two support platforms (12).

4. The novel battery cell tab welding performance defect detection structure according to claim 1, characterized in that, The tester (30) is equipped with four probes (31), which are connected in pairs to the positive electrode (21) and negative electrode (22) of the battery cell (20).

5. The novel battery cell tab welding performance defect detection structure according to claim 4, characterized in that, The tester (30) and the battery cell (20) are provided with a connecting wire (32) for electrical connection. There are four connecting wires (32). One end of the four connecting wires (32) is connected to the tester (30), and the other end of each of the four connecting wires (32) is provided with a probe (31). Two of the four connecting wires (32) are connected to the positive terminal (21) of the battery cell (20) through the probe (31), and the other two connecting wires (32) are connected to the negative terminal (22) of the battery cell (20) through the probe (31).

6. The novel battery cell tab welding performance defect detection structure according to claim 5, characterized in that, The connecting line (32) is a twisted pair cable.

7. The novel battery cell tab welding performance defect detection structure according to claim 5, characterized in that, A shielding wire (40) is provided between the positive electrode (21) and the negative electrode (22) of the battery cell (20). The shielding wire (40) is arranged along the length direction of the battery cell (20), and one end of the shielding wire (40) is connected to the probe (31) of the two connecting wires (32) connected to the positive electrode (21) of the battery cell (20), and the other end of the shielding wire (40) is connected to the probe (31) of the two connecting wires (32) connected to the negative electrode (22) of the battery cell (20).

8. The novel battery cell tab welding performance defect detection structure according to claim 7, characterized in that, The shielding line (40) is arranged in a straight line and is parallel to the battery cell (20).

9. A novel battery cell tab welding performance defect detection structure according to claim 4, characterized in that, The tester (30) uses a low-frequency scanning test method for testing.

10. A novel battery cell tab welding performance defect detection structure according to claim 3, characterized in that, The test fixture (10) has a soft pad (50) on the support (12) that contacts the positive electrode (21) and negative electrode (22) of the battery cell (20).

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