Leakage detection device and method for metal shell lithium battery

Abstract

The invention belongs to the technical field of new energy battery leak hunting, and discloses a leak hunting device for a metal shell lithium battery and a method thereof.The leak hunting device for the metal shell lithium battery comprises a valve, the air inlet end of the valve is communicated with a compressed air source through a communicating pipe, and the air outlet end of the valve is communicated with a pressure regulating valve through an air guide pipe; the air outlet end of the pressure regulating valve is communicated with a communicating thin tube, and the other end of the communicating thin tube is communicated with a stainless steel needle tube used for being inserted into the leak hunting battery. A battery clamp for protecting a shell of the leak detection battery is arranged on the outer side of the leak detection battery; according to the invention, air tightness detection can be carried out on the metal shell lithium battery after laser welding is completed, the overall structure is simple, the shell deformation phenomenon of the battery in the detection process can be prevented, the lithium battery detection safety is improved, the detection process is simple, the battery shell can be comprehensively detected, the use is convenient, and the detection effect can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy battery leakage detection, and specifically, relates to a leakage detection device and method for metal shell lithium batteries, which can be used to detect the air tightness of a closed space formed by laser welding, and can be used to check the welding air tightness of metal shell lithium ion batteries. Background Art

[0002] In recent years, as oil resources have become increasingly scarce, the new energy industry has received more and more attention, and lithium-ion batteries have become a key national research project.

[0003] Metal shell lithium-ion batteries occupy a large share of the market; lithium-ion batteries have superior performance compared to lead-acid batteries, and also have more stringent requirements for the manufacturing process. Among them, moisture control is very important. Lithium-ion batteries with excessive moisture will have a great impact on various performances. There are two main factors that cause lithium-ion batteries to have excessive moisture: one is that the moisture control is not in place during the manufacturing process and the moisture content of the electrode exceeds the standard; the other is that there are leaks after the manufacturing is completed, and moisture enters the battery with the air.

[0004] Therefore, it is very important to use necessary methods to detect defective products with poor sealing after the battery laser welding is completed; the Chinese patent with patent application number: CN201920653547.X discloses a simple leak detection device for aluminum shell lithium batteries, including a pressure relief bottle and a leak detection bottle interconnected by a connecting tube, the leak detection bottle is filled with dimethyl carbonate solution, one end of the connecting tube is located in the leak detection bottle and is inserted into the lower part of the liquid level of the dimethyl carbonate solution, and the inner cavity of the pressure relief bottle is connected to a stainless steel needle that can be inserted into the test battery through a detection tube.

[0005] The above-mentioned existing battery leak detection device of this type can perform air tightness detection on metal shell lithium-ion batteries after laser welding. First, high-pressure gas is injected into the test battery, and the air tightness of the battery can be detected by observing whether bubbles are generated in the inserted part of the connecting tube immersed in the dimethyl carbonate solution. However, the overall structure of this type of existing battery leak detection device is complex, and there is high pressure inside the battery, which can easily cause the battery shell to deform and bulge, affecting the service life of the battery. There are safety hazards, and the detection effect is low. The battery shell cannot be fully detected, which reduces the use effect. Summary of the invention

[0006] The problem to be solved by the present invention is to provide a leak detection device and method for metal shell lithium batteries, which can perform airtightness detection on metal shell lithium batteries after laser welding. The overall structure is simple, which can prevent the battery shell from deforming during the detection process, thereby improving the safety of lithium battery detection. The detection process is simple, and the battery shell can be fully detected. It is easy to use and can improve the detection effect.

[0007] To solve the above problems, the present invention adopts the following technical solutions: A leak detection device for a metal shell lithium battery includes a valve. The air inlet end of the valve is communicated with a compressed air source through a connecting pipe. The air outlet end of the valve is communicated with a pressure regulating valve through a guide pipe. The air outlet end of the pressure regulating valve is communicated with a connecting thin pipe. The other end of the connecting thin pipe is communicated with a stainless steel needle tube for inserting into the leak detection battery. A battery fixture for protecting the outer shell of the leak detection battery is arranged outside the leak detection battery.

[0008] The following is a further optimization of the above technical solutions by the present invention: When the valve is opened, the compressed air source outputs compressed gas and transports it to the pressure regulating valve through the guide pipe. Then, after automatic pressure regulation by the pressure regulating valve, it is transported to the stainless steel needle tube through the connecting thin pipe. At this time, the stainless steel needle tube is used to output compressed gas.

[0009] Further optimization: A sealing plastic pad is sleeved at the end of the stainless steel needle tube. The stainless steel needle tube is inserted into the battery liquid injection hole of the leak detection battery. The sealing plastic pad is used to seal the connection between the stainless steel needle tube and the battery liquid injection hole.

[0010] Further optimization: It further includes a transparent tank body, and the leak detection battery is erected and placed in the transparent tank body.

[0011] Further optimization: Liquid alcohol is stored in the transparent tank body, and the liquid level of the liquid alcohol is at a position 2 - 4 cm above the top weld of the leak detection battery.

[0012] Further optimization: The battery fixture includes two symmetrically and parallelly arranged positioning plates. A plurality of positioning columns are arranged between the positioning plates. The two ends of the positioning columns are respectively detachably connected to the corresponding positioning plates.

[0013] Further optimization: A positioning cavity is arranged between the two positioning plates. The width M of the positioning cavity is the thickness H of the leak detection battery plus 1 mm; the height of the positioning cavity matches the height of the leak detection battery.

[0014] Further optimization: A handle is fixedly installed on any one of the positioning plates near its upper end position. The handle is used to conveniently pick up the battery fixture.

[0015] The present invention also provides a leak detection method for a metal shell lithium battery. Based on the above leak detection device for a metal shell lithium battery, the leak detection method includes the following steps: Step 1. Environmental requirements: The environmental temperature is 23 - 25 °C, the environmental humidity is 20 - 25%; the dew point of the compressed air is < -40 °C; after confirming that the external environmental temperature, humidity, and dew point of the compressed air meet the test requirements; pour an appropriate amount of alcohol into the transparent tank body. The liquid level standard of the alcohol is: when the leak detection battery is placed in the alcohol, the alcohol liquid level should submerge 2 - 4 cm above the battery weld when the battery is erected. Step 2: After preparation, start detecting the battery: Place the leak-detection battery in the middle position of the battery fixture. Open the valve, insert the stainless steel syringe through the battery liquid injection hole into the leak-detection battery, and make the sealing plastic pad closely adhere to the periphery of the battery liquid injection hole to ensure that the input compressed air will not leak from the battery liquid injection hole; Step 3: The compressed air source outputs compressed gas and injects it into the leak-detection battery through the stainless steel syringe. The leak-detection battery is vertically placed in the transparent tank body with the electrode post on top, and the alcohol completely submerges the leak-detection battery. Let it stand for 3 - 5 s, and observe whether there are bubbles emerging at the weld seams around the leak-detection battery. If there are no bubbles, it proves that the battery is well welded; if there are bubbles emerging, it proves that the welding is poor; Step 4: After confirming the welding effect, pull out the stainless steel syringe and take out the leak-detection battery from the battery fixture. Wipe the qualified leak-detection battery clean with a dry cloth and transfer it downward; wipe the leak-detection battery with welding defects clean with a dry cloth as well, mark the defective position with a marker pen, and return it to the laser welding process for repair; Step 5: Pour the alcohol in the transparent tank body back into the alcohol bottle, and then place it in the alcohol storage warehouse.

[0016] Further optimization: The pressure of the compressed gas output by the compressed air source is 0.1 - 0.3 Mpa.

[0017] Adopting the above scheme, the present invention has a clever concept, a reasonable structure, a simple overall structure, can quickly detect the leak of the metal shell lithium battery, can quickly detect the welding airtightness of the metal shell lithium battery. At the same time, using alcohol during detection can effectively prevent moisture from entering the battery during the detection process and affecting the battery performance. In addition, the test accuracy is high, the battery will not undergo large deformation and does not affect the appearance, and it can also be flexibly adjusted according to the production capacity, quickly adding workstations to improve the use effect.

[0018] The present invention can perform airtightness detection on the metal shell lithium battery after laser welding. The overall structure is simple, it can prevent the phenomenon of shell deformation of the battery during the detection process, improve the safety of lithium battery detection, the detection process is simple, it can comprehensively detect the battery shell, is easy to use, and can improve the detection effect.

[0019] The following further illustrates the present invention with reference to the drawings and embodiments. Brief Description of the Drawings

[0020] Figure 1 It is the overall structure schematic diagram of the leak-detection device in the embodiment of the present invention; Figure 2 For Figure 1 The partial enlarged view of A in Figure 3 It is the structure schematic diagram of the battery fixture in the embodiment of the present invention.

[0021] In the figure: 1 - leak detection battery; 2 - compressed air source; 3 - air duct; 4 - valve; 5 - pressure regulating valve; 6 - connecting thin tube; 7 - stainless steel needle tube; 8 - sealing plastic pad; 9 - transparent tank body; 10 - battery liquid injection hole; 11 - battery fixture; 111 - positioning plate; 112 - positioning column; 113 - positioning cavity; 114 - handle. Detailed implementation method

[0022] Example 1, as Figures 1-3 shown, a leak detection device for a metal shell lithium battery includes a valve 4. The air inlet end of the valve 4 is connected to the compressed air source 2 through a connecting pipe, and the air outlet end of the valve 4 is connected to a pressure regulating valve 5 through an air duct 3. The air outlet end of the pressure regulating valve 5 is connected to a connecting thin tube 6, and the other end of the connecting thin tube 6 is connected to a stainless steel needle tube 7 for inserting into the leak detection battery 1; a battery fixture 11 for protecting the outer shell of the leak detection battery 1 is arranged outside the leak detection battery 1.

[0023] In this embodiment, the valve 4 can control the start and stop of the compressed air source 2 at any time, and is thus used to control whether the compressed air source 2 outputs compressed gas.

[0024] In this embodiment, the valve 4 can be one of an electric valve and a mechanical valve. When the valve 4 is opened, the compressed air source 2 outputs compressed gas and transports it through the air duct 3 to the pressure regulating valve 5. Then, after automatic pressure regulation by the pressure regulating valve 5, it is transported through the connecting thin tube 6 to the stainless steel needle tube 7. At this time, the stainless steel needle tube 7 is used to output compressed gas.

[0025] In this embodiment, the air duct 3 is made of a plastic air duct, and the connecting thin tube 6 is made of a plastic thin tube, making the overall structure simple, and the production and manufacturing costs low, improving the use effect; and the pipes made of plastic can make each pipe elastic, avoiding the phenomenon that the outer shell of the leak detection battery 1 bulges due to too high air pressure inside the leak detection battery 1.

[0026] In this embodiment, the pressure regulating valve 5 is a prior art and can flexibly adjust the air pressure of the compressed air entering the stainless steel needle tube 7, which is convenient for use.

[0027] A sealing plastic pad 8 is sleeved on the end of the stainless steel needle tube 7. The stainless steel needle tube 7 is inserted into the battery liquid injection hole 10 of the leak detection battery 1, and the sealing plastic pad 8 is used to seal the connection between the stainless steel needle tube 7 and the battery liquid injection hole 10.

[0028] In this embodiment, a through hole is opened in the middle of the stainless steel needle tube 7, and the through hole is communicated with the connecting thin tube 6.

[0029] In this embodiment, the overall length of the stainless steel needle tube 7 is 8 - 10 mm.

[0030] The leak detection device for the metal shell lithium battery further includes a transparent tank body 9, and the leak detection battery 1 is vertically placed in the transparent tank body 9.

[0031] In this embodiment, the transparent tank body 9 is preferably a square transparent glass cylinder, or it can also be a tank body made of transparent materials (such as plastics, acrylic plates, etc.).

[0032] The transparent tank body 9 stores liquid alcohol, and the liquid level of the liquid alcohol is 2-4 cm above the pole column of the leak detection battery 1, that is, the leak detection battery 1 is completely immersed in the liquid alcohol.

[0033] In addition to this embodiment, the liquid level of the liquid alcohol can also be below the upper end face of the pole column and at a position 2-4 cm above the uppermost weld of the leak detection battery 1, that is, the liquid level of the liquid alcohol is higher than the uppermost weld of the leak detection battery 1, so that the uppermost weld of the leak detection battery 1 is immersed in the liquid alcohol.

[0034] The battery fixture 11 is arranged outside the leak detection battery 1 and is used to protect the outer shell of the leak detection battery 1 to prevent the outer shell of the leak detection battery 1 from bulging during the pressure detection process.

[0035] The battery fixture 11 includes two symmetrically and parallelly arranged positioning plates 111, and a plurality of positioning columns 112 are arranged between the positioning plates 111. The two ends of the positioning columns 112 are respectively detachably connected to the corresponding positioning plates 111.

[0036] In this embodiment, the plurality of positioning columns 112 are arranged in parallel and at intervals, and the positioning columns 112 are used to define the distance between the two positioning plates 111.

[0037] In this embodiment, the positioning plate 111 is made of PP board, and the thickness of the positioning plate 111 is 10±1 mm; the surface of the PP board material is smooth, so that even if the leak detection battery 1 deforms, it can be easily removed from the battery fixture 11, which is convenient for use.

[0038] A positioning cavity 113 is arranged between the two positioning plates 111. The width M of the positioning cavity 113 is 1 mm more than the thickness H of the leak detection battery 1; the height of the positioning cavity 113 matches the height of the leak detection battery 1.

[0039] A handle 114 is fixedly installed on any one of the positioning plates 111 near its upper end position, and the handle 114 is used to facilitate the taking of the battery fixture 11.

[0040] A leak detection method for a metal shell lithium battery, based on the above-mentioned leak detection device for a metal shell lithium battery, the leak detection method includes the following steps: Step 1. Environmental requirements: The environmental temperature is 23°C, and the environmental humidity is 25%; the dew point of compressed air is -45°C; after confirming that the external environmental temperature, humidity, and dew point of compressed air meet the test requirements; pour an appropriate amount of alcohol into the transparent tank 9, and the liquid level standard of alcohol is: when the leak detection battery is placed in alcohol, when the battery is erected, the alcohol liquid level should exceed 2 cm above the battery weld.

[0041] Step 2. After preparation, start testing the battery: Take the leak detection battery 1 and place it in the middle position of the battery fixture 11. Open the valve 4, insert the stainless steel syringe 7 into the leak detection battery 1 through the battery liquid injection hole 10. The sealing plastic gasket 8 is closely attached to the periphery of the battery liquid injection hole 10 to ensure that the input compressed air will not leak from the battery liquid injection hole 10 (confirm the insertion depth according to the size of the leak detection battery 1: the standard insertion depth is that the stainless steel syringe 7 completely passes through the liquid injection hole but does not touch any internal materials).

[0042] Step 3. The compressed air source 2 outputs 0.2 Mpa of compressed gas and injects it into the leak detection battery 1 through the stainless steel syringe 7. The leak detection battery 1 is vertically placed in the transparent tank 9 with the pole column on top, and the alcohol completely submerges the leak detection battery 1. Let it stand for 3 s, and observe whether there are bubbles emerging from the welds around the leak detection battery 1. If there are no bubbles, it proves that the battery welding is good; if there are bubbles emerging, it proves that the welding is bad.

[0043] Step 4. After confirming the welding effect, pull out the stainless steel syringe 7, take out the leak detection battery 1 from the battery fixture 11. Wipe the qualified leak detection battery 1 clean with a dry cloth and transfer it downward; wipe the leak detection battery 1 with welding defects clean with a dry cloth as well, mark the defective position with a marker pen, and return it to the laser welding process for repair. After the repaired battery undergoes secondary laser welding, it is re-tested for leaks until the welding is qualified or it is confirmed that it cannot be repaired.

[0044] Step 5. After all the leak detection batteries 1 have been tested for leaks, the qualified leak detection batteries 1 are transferred downward, and the scrapped leak detection batteries 1 are uniformly disposed of; pour the alcohol in the transparent tank 9 back into the alcohol bottle, and then put it into the alcohol storage warehouse for storage and wait for the next use.

[0045] Example 2, as Figures 1-3 shown, a leak detection method for a metal shell lithium battery, based on the above-mentioned leak detection device for a metal shell lithium battery, the leak detection method includes the following steps: Step 1. Environmental requirements: The environmental temperature is 25°C, and the environmental humidity is 20%; the dew point of compressed air is -42°C; after confirming that the external environmental temperature, humidity, and dew point of compressed air meet the test requirements; pour an appropriate amount of alcohol into the transparent tank 9, and the liquid level standard of alcohol is: when the leak detection battery is placed in alcohol, when the battery is erected, the alcohol liquid level should exceed 4 cm above the battery weld.

[0046] Step 2. After preparation, start testing the battery: Place the leak detection battery 1 at the middle position of the battery fixture 11. Open the valve 4, insert the stainless steel syringe 7 into the leak detection battery 1 through the battery liquid injection hole 10. The sealing plastic gasket 8 is closely attached to the periphery of the battery liquid injection hole 10 to ensure that the input compressed air will not leak from the battery liquid injection hole 10 (confirm the insertion depth according to the size of the leak detection battery 1: the standard insertion depth is that the stainless steel syringe 7 completely passes through the liquid injection hole but does not touch any internal materials).

[0047] Step 3. The compressed air source 2 outputs 0.15 Mpa of compressed gas and injects it into the leak detection battery 1 through the stainless steel syringe 7. The leak detection battery 1 is vertically placed in the transparent tank 9 with the pole column on top, and the alcohol completely submerges the leak detection battery 1. Let it stand for 4 s, and observe whether there are bubbles emerging at the weld seams around the leak detection battery 1. If there are no bubbles, it proves that the battery welding is good; if there are bubbles emerging, it proves that the welding is poor.

[0048] Step 4. After confirming the welding effect, pull out the stainless steel syringe 7 and take out the leak detection battery 1 from the battery fixture 11. The qualified leak detection battery 1 is wiped clean with a dry cloth and transferred downward; the leak detection battery 1 with poor welding is also wiped clean with a dry cloth, the defective position is marked with a marker pen, and it is returned to the laser welding process for repair. After the repaired battery undergoes secondary laser welding, it is re-tested for leaks until the welding is qualified or it is confirmed that it cannot be repaired.

[0049] Step 5. After all the leak detection batteries 1 have been tested for leaks, the qualified leak detection batteries 1 are transferred downward, and the scrapped leak detection batteries 1 are uniformly scrapped; the alcohol in the transparent tank 9 is poured back into the alcohol bottle, and then placed in the alcohol storage warehouse for storage waiting for the next use.

[0050] Those of ordinary skill in the art in this technical field should recognize that the above embodiments are only used to illustrate the present invention, rather than to limit the present invention. As long as it is within the scope of the essential spirit of the present invention, the changes and modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A leak detection device for a metal shell lithium battery, comprising a valve (4), characterized in that: The air inlet end of the valve (4) is connected to the compressed air source (2) via a connecting pipe, the air outlet end of the valve (4) is connected to a pressure regulating valve (5) via an air guide pipe (3), the air outlet end of the pressure regulating valve (5) is connected to a connecting capillary (6), and the other end of the connecting capillary (6) is connected to a stainless steel needle tube (7) for inserting into the inside of the leak detection battery (1); a battery clamp (11) for protecting the outer shell of the leak detection battery (1) is arranged on the outside of the leak detection battery (1).

2. A leak detection device for a metal shell lithium battery according to claim 1, characterized in that: The valve (4) is opened, and the compressed gas source (2) outputs the compressed gas, which is transported to the pressure regulating valve (5) through the air guide pipe (3). The pressure regulating valve (5) then automatically regulates the pressure and transports the compressed gas to the stainless steel needle tube (7) through the connecting capillary (6). At this time, the stainless steel needle tube (7) is used to output the compressed gas.

3. A leak detection device for a metal shell lithium battery according to claim 2, characterized in that: A sealing plastic pad (8) is sleeved on the end of the stainless steel needle tube (7). The stainless steel needle tube (7) is inserted into the battery liquid injection hole (10) of the leak detection battery (1). The sealing plastic pad (8) is used to seal the connection between the stainless steel needle tube (7) and the battery liquid injection hole (10).

4. A leak detection device for a metal shell lithium battery according to claim 3, characterized in that: It also includes a transparent tank body (9), in which the leak detection battery (1) is placed upright.

5. A leak detection device for a metal shell lithium battery according to claim 4, characterized in that: Liquid alcohol is stored in the transparent tank (9), and the liquid level of the liquid alcohol is located at a position 2 to 4 cm above the uppermost weld of the leak detection battery (1).

6. A leak detection device for a metal shell lithium battery according to claim 5, characterized in that: The battery clamp (11) comprises two symmetrical and parallel positioning plates (111), a plurality of positioning columns (112) are arranged between the positioning plates (111), and two ends of the positioning columns (112) are respectively detachably connected to corresponding positioning plates (111).

7. A leak detection device for a metal shell lithium battery according to claim 6, characterized in that: A positioning cavity (113) is provided between the two positioning plates (111); the width M of the positioning cavity (113) is the thickness H of the leak detection battery (1) plus 1 mm; and the height of the positioning cavity (113) matches the height of the leak detection battery (1).

8. A leak detection device for a metal shell lithium battery according to claim 7, characterized in that: A handle (114) is fixedly mounted on any one of the positioning plates (111) near its upper end, and the handle (114) is used to facilitate taking the battery clamp (11).

9. A leak detection method for a metal shell lithium battery, based on the leak detection device for a metal shell lithium battery according to claim 8, characterized in that: The side leakage method includes the following steps: Step 1, environmental requirements: ambient temperature is 23-25°C, ambient humidity is 20-25%; compressed air dew point is <-40°C; after confirming that the external ambient temperature, humidity, and compressed air dew point meet the test requirements; pour an appropriate amount of alcohol into the transparent tank (9). The alcohol level standard is: when the leak detection battery is placed in the alcohol, the alcohol level is 2-4 cm above the battery weld when the battery is upright; Step 2: After the preparation is complete, start testing the battery: take the leak test battery (1) and place it in the middle of the battery fixture (11), open the valve (4), insert the stainless steel needle tube (7) into the leak test battery (1) through the battery injection hole (10), and place the sealing plastic pad (8) tightly around the battery injection hole (10) to ensure that the input compressed air will not leak from the battery injection hole (10); Step 3: The compressed gas source (2) outputs compressed gas and injects it into the leak detection battery (1) through the stainless steel needle tube (7). The leak detection battery (1) is placed vertically in the transparent tank (9) with the pole on top. The alcohol completely covers the leak detection battery (1). The battery is left to stand for 3 to 5 seconds. Observe whether there are bubbles at the welds around the leak detection battery (1). If there are no bubbles, it proves that the battery is well welded; if there are bubbles, it proves that the welding is poor. Step 4: After confirming the welding effect, unplug the stainless steel needle tube (7), take out the leak test battery (1) from the battery fixture (11), wipe the qualified leak test battery (1) with a dry cloth and transfer it downward; wipe the poorly welded leak test battery (1) with a dry cloth, mark the poor position with a marker, and return to the laser welding process for repair; Step 5: Pour the alcohol in the transparent tank (9) back into the alcohol bottle and then put it into the alcohol storage warehouse.

10. A leak detection method for a metal shell lithium battery according to claim 9, characterized in that: The pressure of the compressed gas output by the compressed gas source (2) is 0.1-0.3 MPa.

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