CN111504561A - Method for detecting air tightness of lithium ion battery - Google Patents

Abstract

The invention discloses a method for detecting the air tightness of a lithium ion battery, which comprises the following steps: after the lithium ion battery with a qualified secondary liquid injection amount is directly attached with glue nails on its liquid injection port, welding a sealing sheet to seal; The position of the sealing sheet of the lithium ion battery is filled with helium with positive pressure, and then the lithium ion battery is transferred into the detection cavity for helium content detection. This detection method can effectively eliminate the missed judgment or misjudgment caused by poor welding.

Description

A kind of detection method of air tightness of lithium ion battery

technical field

The invention belongs to the field of lithium ion battery production, and in particular relates to a method for detecting the air tightness of a lithium ion battery.

Background technique

Lithium-ion battery is a secondary battery (rechargeable battery), which mainly relies on the movement of lithium ions between the positive electrode and the negative electrode to work. It has the advantages of high energy, no pollution and long cycle life, so it is widely used in various fields, such as portable electronic products, electric vehicles, large power sources and energy storage fields.

With the rise of the new energy vehicle market, lithium-ion batteries have also developed rapidly. Among them, the safety of lithium-ion batteries has become one of the key directions. Generally speaking, in the production process of lithium-ion batteries, if there is poor welding and the testing equipment does not detect the problem, these defective products have the hidden danger of battery leakage, and the battery with leakage and corrosion will inevitably be harmful to the driver when loaded on the car. and jeopardize the safety of passengers.

At present, the method of detecting gas leakage at the production site is usually the method of returning to helium after the second injection. The injection is finally filled with helium to return to normal pressure, and the battery with qualified liquid injection is installed. After the laser sealing and welding In the helium test again, there is a misjudgment and misjudgment in this method. It is presumed that because the glue nail is too tight, vacuuming the cavity in the cavity to detect the defective products with poor welding, and the lithium-ion battery with the glue nail too tight cannot detect air leakage. , thus causing misjudgment, making defective products flow to the next process and causing safety problems.

SUMMARY OF THE INVENTION

In view of this, it is necessary for the present invention to provide a method for detecting the airtightness of a lithium ion battery. In the present invention, the battery with a qualified secondary liquid injection amount does not need to be filled with helium, and is directly plugged with glue nails after welding and sealing, and then the battery is sealed without welding. After the lithium-ion battery in question is inflated with the helium gas filling nozzle at the position of the welding sealing sheet, the battery is transferred into the detection cavity of the helium detector to detect whether there is helium overflow. The problem that the abnormally sealed battery cannot be detected due to the over-tightening of the air leakage method solves the technical problem of missed judgment or misjudgment existing in the existing gas leakage detection method.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for detecting air tightness of a lithium ion battery, comprising the following steps:

After the lithium-ion battery with qualified secondary injection volume is directly marked with glue nails at its injection port, the sealing sheet is welded and sealed;

After the position of the sealing sheet of the sealed lithium ion battery is filled with helium with positive pressure, the lithium ion battery is transferred into the detection chamber for helium content detection.

Further, the lithium ion battery is an aluminum shell battery or a steel shell battery.

Further, the sealing sheet is sealed by laser welding.

Preferably, the sealing sheet is an aluminum sheet.

Further, the lower surface of the aluminum sheet is in a groove structure, a cavity is formed between the aluminum sheet and the step of the liquid injection port, and the upper end surface of the glue nail is connected to the liquid injection port of the lithium ion battery. 1-2mm longitudinal spacing and the upper end surface of the glue nail does not contact the lower surface of the aluminum sheet.

Further, the specific steps of the helium filling treatment are as follows: align the helium gas inflating nozzle with the position of the sealing sheet to perform helium filling in a mouth-to-mouth manner, and the diameter of the helium gas inflating nozzle is larger than the diameter of the sealing sheet. .

Further, the positive pressure is 20KPa-80KPa.

Further, the step of transferring the lithium ion battery into the detection chamber for helium content detection specifically includes the following steps: using a helium detector to detect helium in the detection chamber, and if helium is detected, the battery Leakage, if the helium content is not detected, the battery is qualified.

Preferably, the parameters of the helium detector are set to 50Pa/8s.

Compared with the prior art, the detection method of the present invention adopts the qualified battery after the secondary liquid injection, installs glue nails, and after laser sealing and welding, then fills the position of the sealing piece with helium gas, and transposes the helium detector in the helium detector. It can effectively detect the airtightness of lithium-ion batteries. Because the welding seam position is directly detected, it can effectively eliminate the problem of missed judgment or misjudgment caused by the over-tightening of the glue plug at the injection port, so that it can be Improve the product quality of lithium-ion batteries and ensure the safety of subsequent use.

Description of drawings

1 is a schematic diagram of the state of the lithium ion battery 10 in the present invention when helium charging is performed;

Fig. 2 is a partial enlarged cross-sectional schematic diagram of part A in Fig. 1;

FIG. 3 is a schematic diagram of the state of the lithium ion battery 10 in FIG. 1 when helium detection is performed.

In the picture: 10-lithium-ion battery, 20-rubber nail, 30-aluminum sheet, 40-helium gas filling nozzle, 50-helium detection cavity.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to specific embodiments. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that a thorough and complete understanding of the present disclosure is provided.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention.

The invention discloses a method for detecting the air tightness of a lithium ion battery, comprising the following steps:

After the lithium-ion battery with qualified secondary injection volume is directly marked with glue nails at its injection port, the sealing sheet is welded and sealed;

After the position of the sealing sheet of the sealed lithium ion battery is filled with helium with positive pressure, the lithium ion battery is transferred into the detection chamber for helium content detection.

In the production and manufacturing process of conventional lithium-ion batteries, after the first injection, there may be some loss of electrolyte. Therefore, it is necessary to perform secondary injection for rehydration to make the injection amount qualified, and then press the injection port. In order to check whether the laser welded seam is defective, a certain amount of helium gas is generally injected into the battery before the rubber nail is sealed, and then the rubber nail is plugged and the helium test is carried out after laser welding. . However, because the rubber nail plug is too tight and the air tightness is too good, helium gas cannot pass through the rubber nail during the helium test, so it is impossible to detect the air tightness of the laser welding part, which makes the battery test with poor welding and too tight rubber nail If there is no air leakage, it will cause misjudgment or missed judgment, and lay a hidden danger for the safe use of lithium-ion batteries. Therefore, in the method for detecting the air tightness of the lithium ion battery adopted in the present invention, the lithium ion battery with a qualified secondary injection volume is no longer subjected to helium charging treatment, and after directly attaching rubber nails, the sealing sheet is welded and sealed, and then the helium gas is inflated. The nozzle is aligned with the position of the sealing sheet, and its inflatable area covers the welding seam area of the sealing sheet sealing laser welding. It is filled with helium with a certain positive pressure, and then the helium detector is transposed for helium detection. It will enter the cavity between the sealing sheet and the glue nail through the welding seam, and when the helium gas is detected, the helium gas will overflow through the welding seam again, so as to detect the poor welding seam; The gas will not enter the battery, and when the helium test is performed again, there will be no helium overflow. The detection method can effectively eliminate the phenomenon that the poorly welded lithium-ion battery cannot be detected due to the over-tightening of the glue plug at the injection port.

Further, the lithium ion battery is an aluminum shell battery or a steel shell battery.

Further, the sealing sheet is sealed by a conventional welding method in the art, and in some specific embodiments of the present invention, the sealing sheet is sealed by laser welding.

Further, the sealing sheet in the present invention is made of conventional materials in the art. Preferably, in some embodiments of the present invention, the sealing sheet is an aluminum sheet.

Further, the lower surface of the aluminum sheet is in a groove structure, a cavity is formed between the aluminum sheet and the step of the liquid injection port, and the upper end surface of the glue nail is connected to the liquid injection port of the lithium ion battery. 1-2mm longitudinal spacing and the upper end surface of the glue nail does not contact the lower surface of the aluminum sheet. It can be understood that the lower surface of the aluminum sheet is designed with a groove structure, and the liquid injection port is designed with a stepped structure inward, mainly for the positioning of the aluminum sheet, and has a good buckle effect. However, the upper end face of the limited rubber nail and the aluminum sheet are not completely fitted, so that there is a certain space between the two, mainly to fill helium gas for the battery with poor sealing and welding, leaving space for helium gas.

Further, the specific steps of the helium filling treatment are as follows: align the helium gas inflating nozzle with the position of the sealing sheet to perform helium filling in a mouth-to-mouth manner, and the diameter of the helium gas inflating nozzle is larger than the diameter of the sealing sheet. .

Further, the positive pressure is 20KPa-80KPa. It can be understood that the positive pressure of helium charging can be adjusted according to the actual situation, such as the capacity of the cavity between the step of the liquid injection port and the sealing sheet, etc., so as to ensure that the helium charging pressure that will not cause deformation of the battery is the Can.

Further, the step of transferring the lithium ion battery into the detection chamber for helium content detection specifically includes the following steps: using a helium detector to detect helium in the detection chamber, and if helium is detected, the battery Leakage, if the helium content is not detected, the battery is qualified.

Preferably, the parameter of the helium detector is set to 50Pa/8s. It can be understood that it can be adjusted according to the specification and model of the battery. Therefore, no specific limitation is required. Here are some specific details of the present invention. parameters in the implementation.

The technical solutions of the present invention will be further clearly and completely described below with reference to specific embodiments.

The specific detection method is as follows: as shown in Figures 1 and 2, the formed lithium ion battery 10 is directly transferred to the secondary injection feeding position for vacuum injection. After the secondary injection volume is qualified, no need For helium-filling treatment, put rubber nails 20 directly on the liquid injection port, and the upper end face of the rubber nail 20 and the liquid injection port have a longitudinal distance of 1-2mm, transfer the lithium-ion battery to the welding station, and make the lower surface a groove structure The aluminum sheet 30 is sealed by laser welding, a cavity is formed between the aluminum sheet 30 and the liquid injection port platform, and the lower surface of the aluminum sheet 30 is not in contact with the upper surface of the rubber nail 20 . Align the helium gas inflator 40 with the position of the aluminum sheet 30 (the diameter of the helium gas inflator 40 is larger than the diameter of the aluminum sheet 30, and the inflatable area includes the welding seam position of the aluminum sheet 30). 10 is transferred into the helium detection chamber 50 for helium detection.

Example 1

Select 1,000 27175195 aluminum shell batteries, and perform secondary vacuum injection after formation. According to the conventional testing steps: batteries with qualified secondary injection volume, fill with helium gas, plug with rubber nails, and after laser sealing and welding, the batteries are transferred to helium The detector detects the cavity, and vacuumizes the helium content to determine whether the battery is leaking. After routine testing, select 1,000 qualified batteries, place the helium gas filling nozzle at the sealing part through the sealing sheet, charge helium gas at 30KPa, and then flow the batteries into the helium gas detection chamber to detect helium gas In this example, the parameter of the helium detector is 30Pa/5s, and it is found that there is a leaking battery. Collect these leaky batteries, do a pressure test on them, and find that there is indeed a problem of poor welding. This method effectively reduces the phenomenon of leakage judgment and reduces the risk of subsequent battery leakage.

Example 2

For one consecutive week, 500 batteries of type 27175195 were selected every day. After forming, a secondary vacuum injection was performed. After the secondary injection volume was qualified, no helium gas treatment was carried out. It is 1-2mm away from the liquid injection port, and then flows into the sealing and welding station. The aluminum sheet with groove structure on the lower surface is used to seal the step hole of the liquid injection port by laser welding. The inflatable nozzle is aligned with the position of the aluminum sheet, and the helium gas is charged with positive 20KPa-80KPa, then the battery is transferred to the helium detection chamber, and the parameter of the helium detector is set to 50Pa/8s, and the helium gas content is detected. If helium is detected, the air tightness is qualified, and if helium is detected, the air tightness is unqualified. Randomly select batteries that pass the air tightness test and batteries that fail the helium test, and conduct a pressure test. The test results are consistent with the judgment. Therefore, it is confirmed that the detection method can effectively eliminate the phenomenon of misjudgment of battery helium leak detection, reduce the risk of subsequent battery leakage, and improve product quality.

The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be regarded as the scope described in this specification.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims (9)

1. a detection method of lithium ion battery air tightness, is characterized in that, comprises the following steps: After the lithium-ion battery with qualified secondary injection volume is directly marked with glue nails at its injection port, the sealing sheet is welded and sealed; After the position of the sealing sheet of the sealed lithium ion battery is filled with helium with positive pressure, the lithium ion battery is transferred into the detection chamber for helium content detection. 2 . The detection method according to claim 1 , wherein the lithium ion battery is an aluminum shell battery or a steel shell battery. 3 . 3. The detection method according to claim 1, wherein the sealing sheet is sealed by laser welding. 4. The detection method according to claim 1 or 3, wherein the sealing sheet is an aluminum sheet. 5. The detection method according to claim 4, wherein the lower surface of the aluminum sheet is a groove structure, a cavity is formed between the aluminum sheet and the step of the liquid injection port, and the There is a longitudinal distance of 1-2 mm between the upper end surface and the liquid injection port of the lithium ion battery, and the upper end surface of the glue nail is not in contact with the lower surface of the aluminum sheet. 6 . The detection method according to claim 1 , wherein the specific step of the helium filling treatment is as follows: aligning the helium gas filling nozzle with the position of the sealing sheet to carry out helium filling in a mouth-to-mouth manner, and the helium filling The diameter of the gas filling nozzle is larger than the diameter of the sealing sheet. 7. The detection method of claim 1, wherein the positive pressure is 20KPa-80KPa. 8 . The detection method according to claim 1 , wherein the step of transferring the lithium-ion battery into a detection cavity for helium content detection specifically comprises the following steps: using a helium detector to detect the content of the helium in the detection cavity. 9 . Carry out helium detection. If helium is detected, the battery is leaking. If the helium content is not detected, the battery is qualified. 9. The detection method according to claim 8, wherein the parameter of the helium detector is set to 50Pa/8s.

Images