Method for inspecting leakage of cylindrical battery

Abstract

According to exemplary embodiments, a method for inspecting leakage of a cylindrical battery is provided. The method for inspecting leakage of a cylindrical battery comprises the steps of: CT-scanning a cylindrical battery in which a can and a top cap of the battery are sealed with a gasket; measuring an end angle of the can of the cylindrical battery and a compression rate of the gasket through the CT-scanned image; and determining whether the cylindrical battery has leaked on the basis of the end angle of the can and the compression rate of the gasket.

Description

Leakage test method for cylindrical batteries

[0001] The present invention relates to a leakage inspection of a cylindrical battery, and specifically to an inspection method capable of determining whether a cylindrical battery is leaking during the operation of a production line.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0031360 dated March 11, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly growing.

[0004] Secondary batteries are classified according to the shape of the battery case into cylindrical or prismatic batteries, in which the electrode assembly is housed in a cylindrical or prismatic case, and pouch-type batteries, in which the electrode assembly is housed in a pouch-type case made of aluminum laminate sheet.

[0005] Cylindrical secondary batteries are sealed by injecting electrolyte into a cylindrical can and assembling a gasket and cap onto the open top of the can. However, if the sealing of the can, cap, and gasket is incomplete, electrolyte leakage may occur. In the event of leakage, the electrolyte, being a flammable substance, leaks out and can cause ignition upon contact with oxygen in the air. Furthermore, moisture penetrating the battery can trigger a decomposition reaction in the electrolyte, potentially leading to ignition or explosion.

[0006] Conventionally, leakage testing of cylindrical batteries was conducted offline. For instance, cylindrical batteries were sampled from the production line, mounted on a leakage pressure gauge, and water was injected into the top of the battery. A hole was then drilled in the bottom to inject nitrogen, and the presence of water bubbles was visually checked to determine if leakage had occurred. Such offline inspections relying on manual work and visual inspection are limited in processing speed and are highly inefficient; furthermore, the results are prone to inaccuracy due to factors such as individual differences among inspectors.

[0007] Therefore, recently, inspection methods have been developed to determine the presence of leakage in cylindrical batteries using fluorescent X-ray analysis. For example, patent documents describe a method of irradiating the cap of a cylindrical battery with X-rays of a specific wavelength and analyzing whether fluorescent X-rays with wavelengths corresponding to the electrolyte components exist within the fluorescent X-rays emitted from the cap to determine the presence of leakage. However, this inspection method cannot accurately inspect cylindrical batteries at high speed, and there are limitations to improving the inspection processing speed.

[0008] The objective of the present invention, which aims to solve the problems of the aforementioned prior art, is to provide a leakage inspection method for determining the quality of a cylindrical secondary battery based on the end angle of a can and the compression ratio of a gasket.

[0009] According to exemplary embodiments of the present invention for achieving the above-mentioned purpose, a method for detecting leakage in a cylindrical battery is provided. The method for detecting leakage in a cylindrical battery comprises: a step of CT scanning a cylindrical battery in which the battery can and top cap are sealed with a gasket; a step of measuring the end angle of the can of the cylindrical battery and the compression ratio of the gasket through the CT scanned image; and a step of determining whether there is leakage in the cylindrical battery based on the end angle of the can and the compression ratio of the gasket.

[0010] The above CT scan can be performed while the production line of the above cylindrical battery is in operation.

[0011] The above CT scan can be performed immediately after sealing the can and top cap of the cylindrical battery with a gasket.

[0012] The compression ratio of the above gasket may include both the compression ratio of the upper gasket between the top of the can and the top cap and the compression ratio of the lower gasket between the bottom of the can and the safety vent.

[0013] The above quality determination can be made by establishing a standard logic for the end angle of the can and a standard logic for the compression ratio of the gasket, and determining it as a good product only when both of the established standard logics are satisfied.

[0014] The reference logic for the end angle of the above can can be set to a certain reference value.

[0015] A certain standard value for the end angle of the above can can be set in the range of 20 to 35°.

[0016] The standard logic for the compression ratio of the above gasket can be set to a certain standard value.

[0017] A certain standard value for the compression ratio of the above gasket can be set in the range of 30 to 60% for the upper compression ratio.

[0018] A certain standard value for the compression ratio of the above gasket can be set in the range of 30 to 60% for the compression ratio of the lower part.

[0019] According to the leakage inspection method for a cylindrical battery of the present invention, by determining whether there is leakage in the cylindrical secondary battery based on the end angle of the can and the compression ratio of the gasket, the quality of the battery can be determined without destroying the cylindrical battery.

[0020] In addition, according to the leakage inspection method for cylindrical batteries of the present invention, by non-destructively inspecting for leakage in cylindrical batteries, defective batteries can be rapidly sorted out without stopping the production line, thereby enabling in-line operation.

[0021] In addition, according to the leakage inspection method of the cylindrical battery of the present invention, leakage of the cylindrical battery can be immediately confirmed through non-destructive inspection, thereby preventing the disposal of unnecessary cells and increasing the yield.

[0022] The effects obtainable from the exemplary embodiments of the present invention are not limited to those mentioned above, and other unmentioned effects can be clearly derived and understood by those skilled in the art to which the exemplary embodiments of the present disclosure belong from the following description. That is, unintended effects resulting from the implementation of the exemplary embodiments of the present disclosure can also be derived by those skilled in the art from the exemplary embodiments of the present disclosure.

[0023] Figure 1 is an overall internal configuration diagram of a typical cylindrical secondary battery.

[0024] Figure 2 is a detailed structural diagram of the cap portion of the cylindrical secondary battery of Figure 1.

[0025] FIG. 3 is a flowchart of a leakage inspection method for a cylindrical secondary battery according to the present invention.

[0026] FIGS. 4a and 4b are partial cross-sectional structural diagrams of a cylindrical secondary battery, FIG. 4a is a schematic diagram for explaining the reference logic for determining the end angle of the can of the present invention, and FIG. 4b is a schematic diagram for explaining the compression ratio of the gasket.

[0027] FIGS. 5A and FIGS. 5B are photographs of the cap portion of a cylindrical battery taken by a leakage inspection method according to a specific example, where FIG. 5A shows a defective product and FIG. 5B shows a good product.

[0028] FIGS. 6a and 6b are photographs of the cap portion of a cylindrical battery taken by a leakage inspection method according to a specific example, where FIG. 6a represents an inventive example and FIG. 6b represents a comparative example.

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Instead, based on the principle that the inventor can appropriately define the concepts of terms to best describe his invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention.

[0030] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0031] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0032] Since embodiments of the present invention are provided to more fully explain the invention to those skilled in the art, the shapes and sizes of the components in the drawings may be exaggerated, omitted, or schematically depicted for clearer explanation. Accordingly, the size or proportion of each component does not entirely reflect the actual size or proportion.

[0033]

[0034] (Example)

[0035] FIG. 1 is an overall internal configuration diagram of a general cylindrical secondary battery (100), and FIG. 2 is a detailed structural diagram of the cap portion of the cylindrical secondary battery (100) of FIG. 1.

[0036] Referring to the drawing, the cylindrical secondary battery (100) has an electrode assembly (120) housed inside a hollow cylindrical can (110) with an open top side, and after an electrolyte is injected into the cylindrical can (110), a top cap (130) is attached to the open top of the cylindrical can (110).

[0037] The electrode assembly (120) has a jelly roll structure formed by stacking the positive electrode (121), the negative electrode (122), and the separator (123) in sequence and rolling them into a round shape.

[0038] As shown in FIG. 2, the top cap (130) forms a positive terminal in a protruding shape and has an exhaust port perforated therein, and is seated on the upper beading portion (110B) of the can (110) together with a ring-shaped gasket (140). The beading portion (110B) of the cylindrical can (110) refers to a point where the inner diameter is bent in a direction that reduces for the seating of the top cap (130) and the gasket (140). A PTC (Positive Temperature Coefficient) element (150), a safety vent (160), and a connection plate (170) are sequentially located at the bottom of the top cap (130).

[0039] The PTC element (150) can cut off the current by significantly increasing the battery resistance when the temperature inside the battery rises.

[0040] The safety vent (160) is shaped to protrude downward in normal conditions and can rupture and vent gas when the pressure inside the battery rises.

[0041] The upper portion of the connection plate (170) is connected to the safety vent (160), and the lower portion is connected to the positive electrode of the electrode assembly (120). Accordingly, under normal operating conditions, the positive electrode of the electrode assembly (120) is connected to the top cap (130) via the lead (172), connection plate (170), safety vent (160), and PTC element (150) to conduct electricity.

[0042] In the case of a cylindrical battery (100) having such a structure, a gap may be created between the can (110) and the gasket (140), which may cause leakage of the electrolyte or penetration of external substances.

[0043] In addition, when the upper portion of the safety vent (160) and the connection plate (170) are joined by welding, there is a possibility that a fine-sized pinhole may be created in the welded joint area due to over-welding. Moisture may penetrate or the electrolyte may leak through such pinholes. Therefore, to ensure the safety of the battery, a leakage test on the battery is absolutely necessary.

[0044] FIG. 3 is a flowchart of a leakage inspection method for a cylindrical secondary battery according to the present invention.

[0045] Referring to FIG. 3, in the leak test method for a cylindrical battery (100), first, the cylindrical battery (100) is CT scanned (S10).

[0046] Specifically, the cylindrical battery (100) is transferred to the top cap supply facility after the electrolyte is injected at the electrolyte injection facility. The supplied battery (100) is clamped by a clamping facility to bend the top (110E) of the can (110) while the gasket (140) and the top cap (130) are seated on the beading portion (110B) of the can (110).

[0047] Next, a CT device is placed in the next process of the clamping device to CT scan the upper part of the cylindrical battery (100) that has been sealed with a can (110) and a top cap (130) during line operation.

[0048] Next, the end angle (θ) of the can (110) of the cylindrical battery (100) and the degree of compression of the gasket (140) are measured through the CT scanned image (S20).

[0049] FIG. 4a is a partial cross-sectional structural diagram of a cylindrical secondary battery (100), and is a schematic diagram for explaining the reference logic based on the measurement of the end angle (θ) of the can (110).

[0050] As shown in FIG. 4a, the measurement of the end angle (θ) of the can (110) of the cylindrical battery (100) can be set based on how much the top (110E) of the can (110) is tilted downward relative to when it is horizontal.

[0051] Here, the end angle (θ) of the can (110) of the cylindrical battery (100) can be set in the range of approximately 20 to 35°. That is, if the end angle (θ) of the can (110) is less than 20°, the compression of the gasket (140) is relatively inferior, and the possibility of leakage of the battery (100) is high. On the other hand, if the end angle (θ) of the can (110) is greater than 35°, unnecessary compression occurs, so it cannot be considered efficient clamping.

[0052] FIG. 4b is a partial cross-sectional structural diagram of a cylindrical secondary battery (100), which is a schematic diagram for explaining the compression ratio of a gasket (140).

[0053] As shown in FIG. 4b, the compression ratio (P) of the gasket (140) of the cylindrical battery (100) needs to take into account both the compression ratio (Pu) of the upper gasket (140u) and the compression ratio (Pd) of the lower gasket (140d).

[0054] The compression ratio (Pu) of the upper gasket (140u) is the compression ratio of the upper gasket (140u) between the top of the can (110) and the top cap (130), and the compression ratio (Pd) of the lower gasket (140d) is the compression ratio of the lower gasket (140d) between the bottom of the can (110) and the safety vent (160).

[0055] The reference logic for the compression ratio (P) of the gasket (140) can be calculated as a percentage of the thickness (t0) before compression and the thickness (t1) after compression of the gasket (140) as shown in Equation 1 below.

[0056]

[0057] The reference logic for the compression ratio (Pu) of the upper gasket (140u) can be set to a certain reference value from Equation 1 above. Likewise, the reference logic for the compression ratio (Pd) of the lower gasket (140d) can also be set to a certain reference value from Equation 1 above.

[0058] A certain reference value for the compression ratio (Pu) of the upper gasket (140u) can be set in the range of approximately 30 to 60%. Additionally, a certain reference value for the lower gasket (140d) can also be set in the range of approximately 30 to 60%.

[0059] Next, the leakage of the cylindrical battery (100) is determined based on the end angle (θ) of the can (110) of the cylindrical battery (100) and the compression ratio (P) of the gasket (140) (S30).

[0060] At this time, the quality judgment of the cylindrical battery (100) can be determined as a good product if both the reference logic for the end angle (θ) of the can (110) and the reference logic for the compression ratio (P) of the gasket (140) satisfy the certain reference values ​​set above. On the other hand, if either of the two condition values ​​deviates from the reference value, it can be determined as a defective product.

[0061] FIGS. 5A and FIGS. 5B are photographs of the cap portion of a cylindrical battery (100) taken by a leak inspection method according to a specific example, FIG. 5A shows a defective product and FIG. 5B shows a good product.

[0062] As can be seen in FIG. 5a, in the case of a defective battery, the end angle (θ) of the can (110) is gentle and the compression ratio (P) of the gasket (140) is not very large. On the other hand, as shown in FIG. 5b, in the case of a good battery, the end angle (θ) of the can (110) forms a sharp downward angle and the compression ratio of the gasket is large. That is, in the leak inspection method of the present invention, the leakage state of the battery can be accurately determined solely by the shape of the battery by CT scanning.

[0063]

[0064] Invention Example 1

[0065] An electrode assembly was inserted into a Model 4680 cylindrical can, and after injecting electrolyte into these cylindrical batteries at an electrolyte injection facility, the can was transferred to a top cap supply facility to place a gasket and a top cap on the beading portion of the battery can, and then the top of the can was clamped by a clamping facility. The top of the assembled cylindrical battery was CT scanned at a CT facility, and the captured image is shown in Fig. 6a.

[0066] In addition, based on the captured image, the end angle (θ) of the can and the degree of compression of the gasket were measured through computer vision analysis, and the end angle (θ) of the can was approximately 30°, the upper compression ratio (Pu) of the gasket was approximately 46%, and the lower compression ratio (Pd) was approximately 50%.

[0067] As can be seen in Fig. 6a, in the case of Invention Example 1, both the end angle (θ) of the can and the compression ratio of the gasket satisfy the conditions of the present invention, and it was confirmed that the shape of the cap part shows a good condition with no leakage of the electrolyte.

[0068]

[0069] Invention Example 2

[0070] For a cylindrical can of the same model as Invention Example 1, a CT scan of the upper part of a cylindrical battery obtained in the same manner as Invention Example 1 was performed, except that the degree of clamping was slightly different, and the captured image is shown in FIG. 6a.

[0071] In addition, based on the captured image, the end angle (θ) of the can and the degree of compression of the gasket were measured in the same manner as in Invention Example 1, and the end angle (θ) of the can was approximately 23°, the upper compression ratio (Pu) of the gasket was approximately 37%, and the lower compression ratio (Pd) was approximately 47%.

[0072] As can be seen in Fig. 6a, in the case of Invention Example 2, both the end angle (θ) of the can and the compression ratio of the gasket satisfy the conditions of the present invention, and it was confirmed that the shape of the cap part shows a good condition with no leakage of the electrolyte.

[0073]

[0074] Invention Example 3

[0075] For a cylindrical can of the same model as Invention Example 1, a CT scan of the upper part of a cylindrical battery obtained in the same manner as Invention Example 1 was performed, except that the degree of clamping was slightly different, and the captured image is shown in FIG. 6a.

[0076] In addition, based on the captured image, the end angle (θ) of the can and the degree of compression of the gasket were measured in the same manner as in Invention Example 1, and the end angle (θ) of the can was approximately 21°, the upper compression ratio (Pu) of the gasket was approximately 39%, and the lower compression ratio (Pd) was approximately 47%.

[0077] As can be seen in Fig. 6a, in the case of Invention Example 3, both the end angle (θ) of the can and the compression ratio of the gasket satisfy the conditions of the present invention, and it was confirmed that the shape of the cap part shows a good condition with no leakage of the electrolyte.

[0078]

[0079] Invention Example 4

[0080] For a cylindrical can of the same model as Invention Example 1, a CT scan of the upper part of a cylindrical battery obtained in the same manner as Invention Example 1 was performed, except that the degree of clamping was slightly different, and the captured image is shown in FIG. 6a.

[0081] In addition, based on the captured image, the end angle (θ) of the can and the degree of compression of the gasket were measured in the same manner as in Invention Example 1, and the end angle (θ) of the can was approximately 26°, the upper compression ratio (Pu) of the gasket was approximately 50%, and the lower compression ratio (Pd) was approximately 44%.

[0082] As can be seen in Fig. 6a, in the case of Invention Example 4, the end angle (θ) of the can and the compression ratio of the gasket both satisfy the conditions of the present invention, and it was confirmed that the shape of the cap part shows a good condition with no leakage of the electrolyte.

[0083]

[0084] Invention Example 5

[0085] For a cylindrical can of the same model as Invention Example 1, a CT scan of the upper part of a cylindrical battery obtained in the same manner as Invention Example 1 was performed, except that the degree of clamping was slightly different, and the captured image is shown in FIG. 6a.

[0086] In addition, based on the captured image, the end angle (θ) of the can and the degree of compression of the gasket were measured in the same manner as in Invention Example 1, and the end angle (θ) of the can was approximately 32°, the upper compression ratio (Pu) of the gasket was approximately 42%, and the lower compression ratio (Pd) was approximately 56%.

[0087] As can be seen in Fig. 6a, in the case of Invention Example 5, both the end angle (θ) of the can and the compression ratio of the gasket satisfy the conditions of the present invention, and it was confirmed that the shape of the cap part shows a good condition with no leakage of the electrolyte.

[0088] The end angle of the can and the compression ratio of the gasket for the above invention examples are summarized in Table 1 below.

[0089] Classification Can End Angle (°) Upper Gasket Compression Ratio (%) Lower Gasket Compression Ratio (%) Leakage Invention Example 1 30 46 50 None Invention Example 2 23 37 47 None Invention Example 3 21 39 47 None Invention Example 4 26 50 44 None Invention Example 5 32 42 56 None Average 26.4 42.8 48.8

[0090]

[0091] Comparative Example 1

[0092] For comparison with the above invention examples, a CT scan of the upper part of a cylindrical battery obtained in the same manner as invention example 1 was performed on a cylindrical can of the same model as invention example 1, except that the degree of clamping pressure was reduced, and the captured image is shown in FIG. 6b.

[0093] In addition, based on the captured image, the end angle (θ) of the can and the degree of compression of the gasket were measured in the same manner as in Invention Example 1, and the end angle (θ) of the can was 0°, the upper compression ratio (Pu) of the gasket was about 15%, and the lower compression ratio (Pd) was about 19%.

[0094] As can be seen in Fig. 6b, in the case of Comparative Example 1, both the end angle (θ) of the can and the compression ratio of the gasket deviate from the conditions of the present invention, and it was confirmed that leakage of the electrolyte was found in the cap portion.

[0095]

[0096] Comparative Example 2

[0097] For a cylindrical can of the same model as Comparative Example 1, a CT scan of the upper part of the cylindrical battery obtained in the same manner as Comparative Example 1 was performed, except that the degree of clamping pressure was slightly different, and the captured image is shown in FIG. 6b.

[0098] In addition, based on the captured image, the end angle (θ) of the can and the degree of compression of the gasket were measured in the same manner as in Comparative Example 1, and the end angle (θ) of the can was 8°, the upper compression ratio (Pu) of the gasket was about 19%, and the lower compression ratio (Pd) was about 25%.

[0099] As can be seen in Fig. 6b, in the case of Comparative Example 2, both the end angle (θ) of the can and the compression ratio of the gasket deviate from the conditions of the present invention, and it was confirmed that a small amount of electrolyte leakage was found in the cap portion.

[0100]

[0101] Comparative Example 3

[0102] For a cylindrical can of the same model as Comparative Example 1, a CT scan of the upper part of the cylindrical battery obtained in the same manner as Comparative Example 1 was performed, except that the degree of clamping pressure was slightly different, and the captured image is shown in FIG. 6b.

[0103] In addition, based on the captured image, the end angle (θ) of the can and the degree of compression of the gasket were measured in the same manner as in Comparative Example 1, and the end angle (θ) of the can was 6°, the upper compression ratio (Pu) of the gasket was about 17%, and the lower compression ratio (Pd) was about 32%.

[0104] As can be seen in Fig. 6b, in the case of Comparative Example 3, both the end angle (θ) of the can and the compression ratio of the gasket deviate from the conditions of the present invention, and it was confirmed that a small amount of electrolyte leakage was found in the cap portion.

[0105]

[0106] Comparative Example 4

[0107] For a cylindrical can of the same model as Comparative Example 1, a CT scan of the upper part of the cylindrical battery obtained in the same manner as Comparative Example 1 was performed, except that the degree of clamping pressure was slightly different, and the captured image is shown in FIG. 6b.

[0108] In addition, based on the captured image, the end angle (θ) of the can and the degree of compression of the gasket were measured in the same manner as in Comparative Example 1, and the end angle (θ) of the can was 0°, the upper compression ratio (Pu) of the gasket was about 10%, and the lower compression ratio (Pd) was about 25%.

[0109] As can be seen in Fig. 6b, in the case of Comparative Example 4, both the end angle (θ) of the can and the compression ratio of the gasket deviate from the conditions of the present invention, and it was confirmed that leakage of the electrolyte was found in the cap portion.

[0110]

[0111] Comparative Example 5

[0112] For a cylindrical can of the same model as Comparative Example 1, a CT scan of the upper part of the cylindrical battery obtained in the same manner as Comparative Example 1 was performed, except that the degree of clamping pressure was slightly different, and the captured image is shown in FIG. 6b.

[0113] In addition, based on the captured image, the end angle (θ) of the can and the degree of compression of the gasket were measured in the same manner as in Comparative Example 1, and the end angle (θ) of the can was 8°, the upper compression ratio (Pu) of the gasket was about 19%, and the lower compression ratio (Pd) was about 32%.

[0114] As can be seen in Fig. 6b, in the case of Comparative Example 5, both the end angle (θ) of the can and the compression ratio of the gasket deviate from the conditions of the present invention, and it was confirmed that a small amount of electrolyte leakage was found in the cap portion.

[0115] The end angle of the can and the compression ratio of the gasket for the above comparative examples are summarized in Table 2 below.

[0116] Classification Can End Angle (°) Upper Gasket Compression Ratio (%) Lower Gasket Compression Ratio (%) Leakage Comparison Example 1 0 15 19 Yes Comparison Example 2 8 19 25 Yes Comparison Example 3 6 17 32 Yes Comparison Example 4 0 10 25 Yes Comparison Example 5 8 19 32 Yes Average 4.4 16 26.6

[0117]

[0118] As can be seen from the examples in Table 1 and Table 2 above, according to the battery leakage inspection method of the present invention, a CT scan image of the cap portion of the battery is extracted, and through this, the leakage of the battery can be accurately and quickly determined based on the end angle of the can and the compression ratio of the gasket.

[0119] The present invention has been described in more detail above through drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are merely one embodiment of the present invention and do not represent all technical concepts of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0120]

[0121] [Explanation of the symbol]

[0122] 100 : Cylindrical battery

[0123] 110 : Can

[0124] 120 : Electrode assembly

[0125] 130 : Top Cap

[0126] 140 : Gasket

[0127] 150 : PTC element

[0128] 160: Safety vent

[0129] 170 : Connection board

Claims

1. A step of CT scanning a cylindrical battery in which the battery can and top cap are sealed with a gasket; A step of measuring the end angle of the can of the cylindrical battery and the compression ratio of the gasket through CT-captured images; and A method for detecting leakage in a cylindrical battery, comprising the step of determining whether the cylindrical battery has leakage based on the end angle of the can and the compression ratio of the gasket.

2. In Paragraph 1, The above CT scan is a method for leak testing of a cylindrical battery, performed while the production line of the cylindrical battery is in operation.

3. In Paragraph 1, The above CT scan is a method for leak testing of a cylindrical battery, performed immediately after sealing the can and top cap of the cylindrical battery with a gasket.

4. In Paragraph 1, A method for leak testing of a cylindrical battery, wherein the compression ratio of the gasket includes both the compression ratio of the upper gasket between the top of the can and the top cap and the compression ratio of the lower gasket between the bottom of the can and the safety vent.

5. In Paragraph 1, A method for leak testing of a cylindrical battery, wherein the above-mentioned pass / fail determination involves setting a standard logic for the end angle of the can and a standard logic for the compression ratio of the gasket, and determining the product as good only when both of the set standard logics are satisfied.

6. In Paragraph 5, A method for leak testing of a cylindrical battery, wherein the reference logic for the end angle of the above-mentioned can is set to a certain reference value.

7. In Paragraph 6, A method for leak testing of a cylindrical battery, wherein a certain standard value for the end angle of the above-mentioned can is set in the range of 20 to 35°.

8. In Paragraph 5, A method for leak testing of a cylindrical battery, wherein the standard logic for the compression ratio of the above gasket is set to a certain standard value.

9. In Paragraph 8, A method for leak testing of a cylindrical battery, wherein a certain standard value for the compression ratio of the above gasket is set in the range of 30 to 60% for the upper compression ratio.

10. In Paragraph 8, A method for leak testing of a cylindrical battery, wherein a certain standard value for the compression ratio of the above gasket is set in the range of 30 to 60% for the compression ratio of the lower part.

Images