Battery can

Abstract

The present invention provides a structure of a battery can comprising: a side wall having an annular cross section and extending in an axial direction; an opening defined by an axially outer end of the side wall; a crimping portion formed by bending the axially outer end of the side wall radially inward; a cap supported by the side wall to cover the opening; and a gasket at least partially interposed in a compressed state between the cap and the crimping portion in the axial direction. The battery can provides a sealing structure in which formation of voids is prevented, a long sealing path that is uninterrupted is secured, and an appropriate compression ratio of the gasket is secured over the entire section of the sealing path.

Description

battery can

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0040429 filed on March 28, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0002] The present invention relates to the structure of a battery can with enhanced sealing properties.

[0003] Secondary batteries, which offer high applicability across product lines and possess electrical characteristics such as high energy density, are widely applied not only to portable devices but also to electric vehicles (EVs) or hybrid electric vehicles (HEVs) powered by electric driving sources.

[0004] These secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency, as they not only have the primary advantage of being able to drastically reduce the use of fossil fuels but also the advantage of not generating any by-products from the use of energy.

[0005] Currently, widely used types of secondary batteries include lithium-ion batteries, lithium-polymer batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries. The operating voltage of these individual secondary battery cells is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, multiple battery cells are connected in series to form a battery pack. Additionally, depending on the charge / discharge capacity required for the battery pack, multiple battery cells are connected in parallel to form a battery pack. Accordingly, the number of battery cells included in the battery pack and the electrical connection type can be set in various ways depending on the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, cylindrical, prismatic, and pouch-type battery cells are known as types of unit secondary battery cells. Among these, cylindrical battery cells are generally constructed by housing an electrode assembly wound in the form of a jelly roll inside a cylindrical battery can.

[0007] FIGS. 1 and 2 show the battery can before and after crimping. Referring to these drawings, the battery can has a side wall (1) that forms an outer surface, and an axial end of the side wall (1) forms an opening (2) that is open so that the electrode assembly can be inserted. The side wall (1) has a beading portion (12) that is recessed radially inward at an axial point. A cap (3) for covering the opening (2) is mounted on the beading portion (12), and the end of the side wall (1) is folded to interpose the cap (3) between it and the beading portion (12) to form a crimping portion (11).

[0008] At this time, a compressible gasket (4) for insulation and / or sealing is interposed between the crimping portion (11) and the cap (3). As the crimping portion (11) is formed, the gasket (4) is compressed between the cap (3) and the crimping portion (11) and between the cap (3) and the beading portion (12) to seal the space between the cap (3) and the side wall (1). The gasket (4) is also interposed radially between the intermediate portion (13) connecting the crimping portion (11) and the beading portion (12) in the axial direction and the radially outer end of the cap (3).

[0009] FIG. 3 shows a void caused by crimping. Referring to this, during the process of bending the side wall (1) to form the crimping portion (11), a void (V) may occur between the crimping portion (11) and the gasket (4), and between the intermediate portion (13) and the gasket (4). In particular, since crimping compresses the space between the crimping portion (11) and the beading portion (12) in the axial direction, no separate compressive force is applied between the intermediate portion (13) and the cap (3). Therefore, the sealing force between the intermediate portion (13) and the cap (3) is very low even when no void (V) occurs.

[0010] In this way, when a void (V) occurs, the risk of moisture or humidity penetrating between the gasket (4) and the side wall (1) increases. Additionally, if moisture penetrates into the void (V) and accumulates, thereby forming a reservoir, the starting point of the seal is substantially pushed back past the void (V), resulting in a shortened sealing path.

[0011] Accordingly, the shape and dimensions of the crimping section and its surroundings need to be set so that a sealing path with appropriate sealing force can be secured for as long as possible without the occurrence of voids.

[0012] The present invention was conceived against the background of the prior art described above, and aims to provide a structure for a battery can with improved sealing and watertightness.

[0013] Specifically, the present invention aims to provide a structure for a battery can in which no gap occurs between the gasket and the side wall, and the gasket can completely seal the space between the side wall and the cap.

[0014] The present invention aims to implement this by determining the appropriate crimping angle of the crimping portion and / or the appropriate degree of compression of the gasket.

[0015] The present invention also aims to provide a structure for a battery can in which the length of a uniformly compressed sealing path can be maximized without being interrupted by a space where moisture can be retained, such as a void in the gasket.

[0016] In particular, the present invention aims to provide a sealing structure for a battery can in which a void occurring adjacent to the folded portion and / or the middle portion of the crimping portion is eliminated, and the gasket can be evenly compressed throughout.

[0017] The present invention also aims to provide a battery can structure having a support structure that supports a gasket so as to minimize deformation of sealing-related members or unnecessary loads applied thereto, which may cause voids or unevenness in the degree of compression.

[0018] The technical problems of the present invention are not limited to the purposes mentioned above, and other unmentioned purposes and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the purposes and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0019] To solve the above problem, the present invention provides a battery can comprising: a side wall having an annular cross-section and extending in the axial direction; an opening defined by an axial outer end of the side wall; a crimping portion formed by bending the axial outer end of the side wall inwardly in the radial direction; a beading portion formed by inwardly sinking a portion of the side wall spaced downward from the crimping portion by a predetermined gap; an intermediate portion extending axially from the side wall and connecting the crimping portion and the beading portion; a cap supported by the side wall to cover the opening; and a gasket axially compressed and interposed between a portion of the side wall including the crimping portion and the beading portion and the cap.

[0020] The above-mentioned crimping portion may be formed by placing the cap fitted with the gasket on the beading portion after the above-mentioned beading portion has been formed first, and by crimping the end of the side wall.

[0021] In this specification, the first thickness (T1) of the gasket is defined as the maximum value of the axial distance between the bottom surface of the crimping portion and the top surface of the cap. Similarly, the second thickness (T2) of the gasket is defined as the minimum value of the axial distance between the bottom surface of the crimping portion and the top surface of the cap.

[0022] This definition applies equally even when the axial distance between the bottom surface of the crimping portion and the top surface of the cap is greater than the thickness of the gasket before compression, regardless of the designation of thickness, so that the first thickness and / or the second thickness becomes greater than the maximum value of the actual thickness of the gasket. That is, in this specification, for example, even if the thickness of the gasket before compression is 2mm and the maximum value of the thickness that the gasket can actually have is 2mm, if the maximum value of the axial distance between the bottom surface of the crimping portion and the top surface of the cap is 2.5mm, the first thickness is defined as 2.5mm. In other words, the dimensions defined by the terms 'first thickness' to 'sixth thickness' in the present invention are dimensions belonging to the remaining structure of the battery can set to allow the gasket to be compressed to a predetermined thickness, and while they 'regulate' the maximum value of the thickness that the gasket can have among certain members, they do not 'define' it. Therefore, cases where the gasket itself has an inappropriate thickness or shrinks and its dimensions are reduced, resulting in it not being properly compressed, may also be included within the scope of the battery can according to the present invention.

[0023] The ratio (T2 / T1) of the second thickness (T2) to the first thickness (T1) may be 0.7 or greater. This reduces the gap between the maximum and minimum axial distances between the crimping part and the cap compared to the conventional method. That is, if the difference between the first thickness and the second thickness is large, the crimping part receives an excessive reaction force at its leading edge, and consequently, the bending portion rises, increasing the likelihood of forming a void. This is because the reaction force due to the elastic restoration of the gasket (4) and the bending moment attempting to bend the side wall (1) act together, causing the bending portion of the side wall (1) to rise. To prevent this, it is necessary to make the degree of compression of the gasket as uniform as possible between the crimping part and the cap.

[0024] In the first comparative example, second comparative example, first embodiment, and second embodiment of the present invention, the amount of moisture penetration was measured by placing a desiccant inside the battery can, leaving it in a humid environment for a certain period of time, and then measuring the increase in weight of the desiccant.

[0025] According to the second embodiment of the present invention, the ratio was set to 0.74. At this time, the moisture penetration amount was 0.029g. On the other hand, according to the second comparative example in which the ratio was set to 0.45, the moisture penetration amount was 0.052g, which was significantly higher than that of the second embodiment. In other test results including these data, it was observed that when the ratio was lower than 0.7, the moisture penetration amount increased significantly.

[0026] At this time, the thickness of the gasket within the section compressed between the crimping portion and the cap and between the beading portion and the cap may be greater than or equal to the second thickness (T2) and less than or equal to the first thickness. Accordingly, the gasket may not have a thickness less than 0.7 times the thickness at any point between a part of the side wall and the cap. In this case, the gasket can be compressed uniformly over the entire section to form a long and stable sealing path.

[0027] In order to reliably reduce the possibility of the above voids occurring, it is preferable that the ratio (T2 / T1) be 0.8 or higher.

[0028] According to the first embodiment of the present invention, the ratio was set to 0.89. At this time, the amount of moisture penetration was 0.021g, which was an even smaller amount compared to the case of the second embodiment.

[0029] Meanwhile, the above ratio (T2 / T1) may be 0.95 or less.

[0030] According to the first comparative example of the present invention, in which the above ratio is set to 1, the amount of moisture penetration was measured to be 0.079g, which is very high. This is because, in order to make the first thickness and the second thickness exactly the same, the degree of bending of the crimping portion is insufficient, and thus the gasket is not sufficiently compressed. That is, in order to enjoy the sealing effect resulting from the compression of the gasket, the second thickness must be at least smaller than the first thickness, and it is preferable that the above ratio be set to 0.95 or less.

[0031] More preferably, the ratio (T2 / T1) may be 0.9 or less. In order for the gasket to sufficiently exert a sealing effect, it is desirable that the maximum compression ratio of the gasket be 0.1 or more. To ensure that the maximum compression ratio of the gasket is 0.1 or more, the ratio must not exceed 0.9. However, the ratio is not limited thereto and may have a value between 0.9 and 0.95.

[0032] A third thickness (T3) may be defined as the radial distance between the middle portion and the outer circumference of the cap. As described above, the crimping portion may be formed by crimping the end of the side wall after the beading portion is formed first, and then the cap fitted with the gasket is inserted onto the beading portion. At this time, if the outer diameter of the gasket before insertion is excessively large compared to the inner diameter of the side wall, the cap and the gasket cannot be properly inserted; therefore, the third thickness, defined as the radial distance between the outer circumference of the cap and the inner circumference of the side wall (the middle portion), may be similar to the thickness of the uncompressed gasket before insertion. Accordingly, under the assumption that the third thickness represents the thickness before compression, the degree of compression of the gasket can be indicated based on the difference between the first thickness and the second thickness and the third thickness.

[0033] In this specification, a first compression ratio and a second compression ratio are defined in relation to a second thickness and a first thickness, respectively. Specifically, the first compression ratio is defined as the ratio of the difference between the third thickness (T3) and the first thickness (T1) to the third thickness (T3), and the second compression ratio is defined as the ratio of the difference between the third thickness (T3) and the second thickness (T2) to the third thickness (T3). That is, the first compression ratio is defined as '1-T1 / T3', and the second compression ratio is defined as '1-T2 / T3'.

[0034] Meanwhile, between the cap and the crimping portion, it is preferable that the first compression ratio (1-T1 / T3) be greater than 0. In other words, it is preferable that the gasket be in a compressed state at least relative to the third thickness at all points between the cap and the crimping portion. If the gasket has uncompressed points between the cap and the crimping portion, a void may occur at those points, or even if no void occurs, those points may become weak points in the seal.

[0035] It is preferable that the first compression ratio (1-T1 / T3) be 0.05 or higher. The first compression ratio may be reduced when the degree of bending of the crimping portion is excessively small or excessively large. In the first comparative example where the first compression ratio is set to 0 because the degree of bending of the crimping portion is excessive, and in the second comparative example where the first compression ratio is set to -0.1 because the degree of bending of the crimping portion is excessive, the moisture penetration amounts were found to be very high at 0.079g and 0.052g, respectively; however, in the first and second embodiments of the present invention where the first compression ratios are set to 0.1 and 0.05, respectively, the moisture penetration amounts were found to be low at 0.021g and 0.029g, respectively.

[0036] Between the cap and the crimping portion, it is preferable that the second compression ratio (1-T2 / T3) be 0.3 or less. If the second compression ratio is excessively large, the reaction force applied by the gasket to the leading edge of the crimping portion becomes excessive, and as a result, the bent portion of the crimping portion rises, which may cause a void. In fact, according to the second comparative example in which the second compression ratio is set to 0.55, the first compression ratio had a negative value of -0.1, which suggests the occurrence of a void.

[0037] It is preferable that the second compression ratio (1-T2 / T3) be 0.1 or higher. This is because the sealing effect of the gasket can be properly exerted only if the compression ratio of the gasket is 0.1 or higher at least at one point between the cap and the crimping portion. If the second compression ratio is less than 0.1, the sealing effect is not properly exerted, no matter how small the difference between the second compression ratio and the first compression ratio may be.

[0038] The above experimental results indicate a difference in sealing force based on the ratio of the maximum and minimum axial distances within the section where the crimping section and the cap overlap; however, in relation to the meaning of the ratio of the upper and lower limits of the thickness at which the gasket is compressed, this can be applied by analogy to other parts sealed by the gasket. That is, even between the bottom surface of the cap and the upper surface of the beading section, if there are points on the gasket with a thickness ratio that differs by more than the first thickness and the second thickness, this causes deformation of the sidewall and / or the cap, which may result in the formation of voids or a weakening of the sealing force. Accordingly, according to one embodiment of the present invention, in the section where the gasket is interposed between the beading section and the cap, by setting the axial distance between the beading section and the cap to be greater than the first thickness and less than or equal to the second thickness, the gasket can be uniformly compressed, and deformation of the beading section and the cap can be prevented, thereby minimizing the occurrence of voids and strengthening the sealing force.

[0039] According to one embodiment, the crimping portion may include: a first bend portion extending from the middle portion and bent such that the slope gradually decreases along the radial inner direction; a pressure portion inclined to have a negative slope with respect to the radial inner direction; and a first bottom portion defined as a portion between the first bend portion and the pressure portion where the slope with respect to the radial direction is zero.

[0040] At this time, the first bottom portion may be extended for a predetermined length in the radial direction, but alternatively, it may be defined as only one point in the radial direction.

[0041] It is preferable that the tip of the pressurizing part be positioned radially inward relative to the outer circumference of the cap. That is, it is preferable that at least a portion of the pressurizing part overlaps with the cap in the axial direction. Accordingly, the gasket can be axially interposed between the pressurizing part and the cap and compressed.

[0042] The crimping angle can be defined as the angle formed by the first bottom part and the pressure part. In this case, the angle formed by the first bottom part and the pressure part refers to the angle formed by the radial direction and the imaginary line segment connecting the boundary of the first bottom part and the pressure part and the tip of the pressure part, that is, the angle formed by the average slope of the pressure part.

[0043] The above crimping angle may be greater than 0 degrees and less than 5 degrees. If the above crimping angle is too small (0 degrees or less), the crimping portion cannot sufficiently pressurize the gasket, and thus the gasket cannot perform a sealing effect. In addition, if the above crimping angle is too large (5 degrees or more), a gap may occur between the first bend portion and the gasket, and the gap may become a weak point in the seal.

[0044] In each of the first comparative example, second comparative example, first embodiment, and second embodiment of the present invention, the crimping angle was set to 0 degrees, 7.5 degrees, 2 degrees, and 4.5 degrees. At this time, under each condition, the amount of moisture penetration was measured by placing a desiccant inside the battery can, leaving it in a humid environment for a certain period of time, and then measuring the increase in weight of the desiccant.

[0045] In the first comparative example, the gasket was hardly compressed, so a high moisture penetration amount of 0.079g was measured. In the second comparative example, the first bottom part and the first folded part rose due to the excessive reaction force applied to the pressurized part, so a high moisture penetration amount of 0.052g was measured.

[0046] In contrast, according to the first and second embodiments in which the crimping angle was appropriately set, the moisture penetration amount was measured to be significantly lower at 0.021g and 0.029g, respectively, and no voids occurred.

[0047] More preferably, the crimping angle may be 4.5 degrees or less. When the crimping angle is set greater than 4.5, the moisture penetration amount was measured to be greater than 0.03g.

[0048] Additionally, preferably, the crimping angle may be 2 degrees or more. When the crimping angle is less than 2 degrees, the minimum compression ratio of the gasket becomes less than 0.1, resulting in a weak seal.

[0049] The above-mentioned pressurizing portion may have an upwardly convex shape in which the slope decreases along the radially inward direction. This may mean that the slope at the tip of the pressurizing portion is greater than the slope of the crimping angle. This may be the result of deformation occurring radially outward during the formation process of the crimping portion. As crimping is performed not only axially inward but also radially outward in this manner, the gasket may be prevented from being pushed out radially inward. Furthermore, in this case, as the gasket receives a force pushing it toward the middle portion, it is compressed toward the first bend portion and the middle portion, allowing it to adhere more closely to the area vulnerable to the formation of voids.

[0050] The first bottom portion may be located radially inward relative to the radially outer end of the cap. This means that if the first bottom portion extends over a predetermined section, the entire predetermined section is located radially inward relative to the radially outer end of the cap. In other words, the first bend portion may extend radially inward relative to the radially outer end of the cap. Accordingly, the portion of the gasket passing through the middle section is subjected to an axially compressive force.

[0051] The above beading portion may include a second bent portion that extends from the above intermediate portion and is bent such that the negative slope gradually decreases along the radial inner direction.

[0052] The second bend portion may extend radially inward relative to the radially outer end of the cap. Accordingly, the portion of the gasket passing through the middle section is subjected to an axial compressive force.

[0053] According to one embodiment of the present invention, as both the first bend portion and the second bend portion extend radially inward relative to the radially outer end of the cap, the entire portion of the gasket passing through the middle portion is axially interposed between the first bend portion and the second bend portion, and as a result of the maximum axial distance between the first bend portion and the second bend portion decreasing as it moves radially outward, the gasket is compressed axially at the point passing through the middle portion.

[0054] Independently thereof, when the maximum value of the radial distance between the side wall and the outer periphery of the cap defines the third thickness, and the minimum distance between the radially outer end of the cap and the crimping portion defines the fourth thickness, the fourth thickness may be greater than or equal to the second thickness and less than the third thickness. If the fourth thickness is smaller than the second thickness, the gasket may be excessively compressed and damaged, and if it is larger than the third thickness, the gasket may not be properly compressed, resulting in a void or a weakened sealing force.

[0055] The above fourth thickness may be less than the above first thickness. Accordingly, the gasket may be compressed axially by the first bend portion more than by the first bottom portion at least.

[0056] As in the configurations described above, when the gasket is compressed axially in the section passing through the middle section, the corresponding part of the gasket undergoes deformation in which its axial cross-sectional area expands due to the Poisson effect. This deformation prevents the phenomenon where the sealing force is weak or a void occurs in the section passing through the middle section because there is no way to compress the gasket radially. That is, unlike other parts where sealing is achieved by compressing the gasket by narrowing the space between the side wall and the cap, sealing is achieved in the outer periphery of the cap and the middle section by expanding the cross-sectional area of ​​the gasket while maintaining the distance between the cap and the middle section.

[0057] The beading portion may extend radially inward beyond the radially inner end of the crimping portion. As the crimping portion is formed, the gasket and the cap receive axially inward pressure distributed in the section overlapping with the crimping portion. At this time, if the beading portion fails to provide a reaction force throughout the entire section where the gasket and the cap receive pressure from the crimping portion, the positions of the resultant force received by the gasket and the cap from the crimping portion and the resultant force received from the beading portion become radially misaligned, resulting in a bending load. Consequently, the gasket may receive an excessively uneven compressive force, or bending deformation may occur in the cap, leading to the formation of voids or structural instability. Therefore, by setting the beading portion to extend radially inward at least further than the crimping portion, a reaction force against the pressure provided by the crimping portion can be provided throughout the entire section, and unnecessary loads or deformations can be prevented.

[0058] Specifically, the section of the gasket supported by the beading portion may extend radially inward beyond the radially inner end of the crimping portion. Here, the phrase "the gasket is supported by the beading portion" means a section in which the gasket is compressed to transmit the reaction force provided by the beading portion to the pressure applied by the crimping portion along the thickness direction, thereby exerting an elastic restoring force, when the direction perpendicular to the extension direction of the gasket (or the tangential direction at a point on the gasket) is defined as the thickness direction of the gasket. This may be defined, for example, as a section where the gasket contacts the bottom surface of the cap, or as a section where the gasket is interposed in the thickness direction between the cap and the beading portion or elastically compressed. In other words, the section in which the reaction force provided by the beading portion to the pressure applied by the crimping portion is transmitted to the cap through the gasket may extend beyond the radially inner end of the crimping portion. Accordingly, unnecessary or unbalanced loads on the cap and gasket can be prevented.

[0059] A current collector plate may be interposed between the gasket and the beading portion. The current collector plate may be electrically connected to the electrode assembly to connect the electrode assembly housed in the battery can to the terminal, but regardless of its name, as long as it is a plate-shaped member interposed between the gasket and the beading portion, it may refer to anything regardless of its precise function and operation.

[0060] At this time, the current collector plate may be extended further inward in the radial direction relative to the gasket. Since the current collector plate is extended radially inward relative to the gasket and is interposed between the beading portion and the gasket, it can provide a reaction force against the axial load applied by the crimping portion to the gasket over the entire length. As such, since a reaction force parallel without staggering is provided against the axial load applied by the crimping portion to the gasket and the cap through it, unnecessary load or deformation is prevented from being applied to the gasket and the cap.

[0061] In the battery can according to one embodiment of the present invention, the current collector plate may be arranged along the circumferential direction in sections interposed between the gasket and the beading portion and in sections not interposed. At this time, the current collector plate may have a shape in which it is spaced apart along the circumferential direction and at least a portion of each has a wing portion that overlaps with the area where the gasket and the beading portion are provided, but the specific shape of the current collector plate is not limited thereto.

[0062] Here, when the fifth thickness is defined as the minimum value of the axial distance between the beading portion and the cap in the section where the current collector plate is not interposed between the gasket and the beading portion, and the sixth thickness is defined as the minimum value of the axial distance between the current collector plate and the cap in the section where the current collector plate is interposed between the gasket and the beading portion, the fifth thickness and the sixth thickness may be greater than or equal to the second thickness and less than or equal to the first thickness. Since it is very difficult to mold the gasket to have different thicknesses in the area where the current collector plate is interposed between the beading portion and the gasket and the area where it is not interposed, by controlling the fifth thickness and the sixth thickness within the range of greater than or equal to the second thickness and less than or equal to the first thickness in this manner, the degree of compression of the gasket may not become excessively uneven despite changes in dimensions along the circumferential direction.

[0063] A first length may be defined as the radial length of the section where the crimping portion and the cap overlap in the axial direction. In this case, the first length may be set to be at least twice the second thickness and the first thickness. It has been confirmed that if the first length is less than twice the second thickness, the bending angle of the crimping portion becomes steeper than 5 degrees to secure an appropriate minimum compression ratio of the gasket, and consequently, there is a high possibility of voids occurring. Furthermore, if the first length is shorter than twice the first thickness, the length relative to the cross-sectional area of ​​the sealing path becomes excessively small, making it easier for moisture to penetrate; and if crimping is performed more strongly to prevent this, deformation due to uneven reaction forces and the resulting occurrence of voids become easier.

[0064] When the maximum value of the radial distance between the middle portion and the outer periphery of the cap defines the third thickness, the thickness of the cap may be less than or equal to the third thickness. When considering the shape of a cross-section of the gasket cut like a cake in an axial section equal to the thickness of the cap, if the thickness of the cap is greater than the third thickness, the shape of the cross-section is formed to be excessively slender, which prevents linear Poisson deformation with respect to compression and causes unintended deformations such as buckling or shear deformation, which may result in weak or uneven adhesion, or the occurrence of voids. Accordingly, by setting the thickness of the cap to be less than or equal to the third thickness so that the portion passing between the middle portion and the outer periphery of the cap in the gasket has a square cross-section or a cross-section that is larger in the radial direction than in the axial direction, the portion may be made to undergo linear Poisson deformation with respect to axial compression.

[0065] The above gasket may include an exposed portion that protrudes radially inward relative to the radially inner end of the crimping portion. In this way, by protruding outward relative to the crimping portion, a portion of the gasket can be compressed to an intended thickness between the leading edge of the crimping portion and the cap. At this time, a second length may be defined as the length of the protruding exposed portion.

[0066] When the first length is defined as the radial length of the section where the crimping portion and the cap overlap in the axial direction, the second length may be less than or equal to half of the first length. Additionally, independently of this, the second length may be less than or equal to twice the second thickness. If the second length is set to an excessively long length, the risk of deformation or load received by the exposed portion, which is not directly supported by other members including the crimping portion, being transferred to the remaining parts of the gasket participating in the seal increases, thereby lowering the stability of the seal. Furthermore, if the second length is too long, the exposed portion is prone to being bent or lifted, and at this time, seepage of moisture may occur through the gap between the exposed portion and the crimping portion and / or between the exposed portion and the cap. Accordingly, by setting the upper limit of the second length as described above, such a decrease in sealing power can be prevented.

[0067] The present invention can provide a structure for a battery can in which the gasket is evenly and properly compressed between the side wall and the cap, thereby improving sealing and watertightness.

[0068] Specifically, one embodiment of the present invention can provide a structure for a battery can in which the gasket can completely seal the side wall and the cap by having an appropriate ratio of thickness and / or compression, while having a crimping angle that is not excessive so that no gap is created between the gasket and the side wall.

[0069] According to one embodiment of the present invention, a structure of a battery can is provided in which a gasket is uniformly compressed so that the length of the sealing path is maximized without being interrupted by a space where moisture can be retained, such as a void.

[0070] According to one embodiment of the present invention, in particular, there is an advantage that voids occurring adjacent to the folded portion and / or intermediate portion of the crimping portion are eliminated, and the gasket is uniformly compressed from the crimping portion to the beading portion.

[0071] A battery can according to one embodiment of the present invention also has a support structure that supports a gasket so that deformation of sealing-related members or unnecessary loads applied thereto, which may cause gaps or unevenness in the degree of compression, can be minimized.

[0072] In addition to the above, the present invention may have various other effects, which are described in each embodiment, or effects that can be easily inferred by a person skilled in the art, etc., will be omitted.

[0073] Figures 1 and 2 show the battery can before and after crimping.

[0074] Figure 3 shows the appearance of voids caused by crimping.

[0075] Figures 4 and 5 show the battery can before and after crimping according to one embodiment.

[0076] Figures 6 and 13 show enlarged views of the main part of Figure 5.

[0077] Figure 7 shows the amount of moisture penetration according to the settings of the crimping angle, compression ratio, and thickness ratio of the examples and comparative examples.

[0078] FIG. 8 shows a gasket according to one embodiment being compressed in the axial direction and adhering to the cap and the middle part.

[0079] Figures 9 and 10 show the presence or absence of bending load applied to the cap depending on the degree of extension of the beading portion.

[0080] FIG. 11 shows the shape of a current collector plate according to one embodiment.

[0081] FIG. 12 shows a portion in which a current collector plate is interposed between the beading portion and the cap in a battery can according to one embodiment.

[0082] [Explanation of the symbol]

[0083] 1: Side wall 11: Crimping section 110: First bending section 111: First bottom section 112: Pressurizing section 12: Beading section 120: Second bending section 121: Second bottom section 13: Middle section 2: Opening 3: Cap 4: Gasket 40: Exposed section 5: Current collector plate 50: Wing section

[0084] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0085] Although terms such as "first," "second," etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0086] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0087] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0088] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0089] Singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may be omitted or additional components or steps may be included.

[0090] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less unless specifically stated otherwise.

[0091] The present invention relates to a cap sealing structure for a battery can that accommodates an electrode assembly to form a battery cell. The battery cell may be a cylindrical battery cell containing a jelly roll-type electrode assembly, but the specific structure of the cell is not limited in the present invention. Although terms such as axial direction, radial direction, and circumferential direction are used in this specification, these are merely terms used for convenience of explanation and are defined relatively rather than being bound by any absolute orientation, such as the direction of gravity.

[0092] Furthermore, it will be easily understood from the following description that the structure of the battery can according to the limitation of the present invention does not necessarily have to have a fixed central axis or a circular cross-section along the axial direction, but can be used in battery housings of any other structure under the premise that the opening is sealed by the side wall being crimped to secure an opening defined by one end of the side wall and a cap covering the opening.

[0093] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0094] First, with reference to FIGS. 4 to 6, the approximate structure and shape of a battery can according to one embodiment of the present invention will be described.

[0095] FIGS. 4 and 5 illustrate the state before and after crimping of a battery can according to one embodiment. Referring to these drawings, a battery can according to one embodiment of the present invention comprises: a side wall (1) having an annular cross-section and extending axially; an opening (2) defined by an axial outer end of the side wall (1); a crimping portion (11) formed by bending the axial outer end of the side wall (1) radially inward; a beading portion (12) formed by inwardly sinking a portion of the side wall (1) spaced downward from the crimping portion (11) by a predetermined gap; an intermediate portion (13) extending axially from the side wall (1) and connecting the crimping portion (11) and the beading portion (12); and a cap (3) supported by the side wall (1) to cover the opening (2). and a gasket axially compressed and interposed between the part of the side wall (1) including the crimping portion (11) and the beading portion (12) and the cap (3).

[0096] The above side wall (1) may be made of a metal material rolled into a tubular shape. For example, the above side wall (1) may be made of a light metal such as aluminum. In order to form the crimping portion (12), it is preferable that the above side wall (1) include a material capable of plastic deformation at least at its axial end.

[0097] It is preferable that the above gasket (4) be made of a material having compressibility and elasticity so that it can seal the two members with elastic restoring force when compressed between the two members.

[0098] The above crimping portion (11) may be formed by placing the cap (3) fitted with the gasket (4) on the beading portion (12) after the above beading portion (12) is formed first, and crimping the end of the side wall (1).

[0099] In the above cap (3), the portion supported by the gasket (4) may be formed as a flat portion extending in a direction intersecting the axial direction. However, the cap (3) may have a three-dimensional shape including a somewhat curved surface, provided that the overall shape extends in a direction intersecting the axial direction.

[0100] FIG. 6 shows an enlarged view of the main part of FIG. 5. Referring thereto, the crimping portion (11) according to the present embodiment may include: a first bend portion (110) extending from the intermediate portion (13) and bent so that the slope gradually decreases along the radial inner direction; a pressure portion (112) inclined to have a negative slope with respect to the radial inner direction; and a first bottom portion (111) defined as a portion between the first bend portion (110) and the pressure portion (112) where the slope with respect to the radial direction is 0.

[0101] At this time, the first bottom portion (111) may be extended a predetermined length in the radial direction, but alternatively, it may be defined as only one point in the radial direction.

[0102] It is preferable that the tip of the pressurizing part (112) be positioned radially inward relative to the outer circumference of the cap (3). That is, it is preferable that at least a portion of the pressurizing part (112) overlaps with the cap (3) in the axial direction. Accordingly, the gasket (4) can be compressed by being interposed axially between the pressurizing part (112) and the cap (3).

[0103] The above beading portion (12) may include: a second bend portion (120) extending from the middle portion (13) and bent such that the negative slope gradually decreases along the radial inner direction; and a second bottom portion (121) extending from the second bend portion (120) and defined as a portion with a slope of 0 in the radial direction.

[0104] At this time, the second bottom part (121) may be extended a predetermined length in the radial direction, just like the first bottom part (111), but may also be defined as only one point in the radial direction.

[0105] Of course, the beading portion (12) may have a shape that does not include the second bottom portion (121). For example, the beading portion (12) may have a shape in which the second bending portion (120) extends from the middle portion (13), and a section with increasing negative slope extends from the second bending portion (120) along the radial inner direction.

[0106] Hereinafter, with reference to FIGS. 6 and 7, the shape elements of the crimping portion (11) in the first embodiment, second embodiment, first comparative example, and second comparative example related to the setting of the first thickness, second thickness, and crimping angle of the present invention, and the amount of moisture penetration and whether voids occur accordingly, will be explained.

[0107] Referring again to FIG. 6, the first thickness (T1) of the gasket (4) is defined as the maximum value of the axial distance between the bottom surface of the crimping portion (11) and the top surface of the cap (3). Similarly, the second thickness (T2) of the gasket (4) is defined as the minimum value of the axial distance between the bottom surface of the crimping portion (11) and the top surface of the cap (3).

[0108] This definition applies equally even when the axial distance between the bottom surface of the crimping portion (11) and the top surface of the cap (3) is greater than the thickness of the gasket (4) before compression, regardless of the designation of thickness, so that the first thickness (T1) and / or the second thickness (T2) becomes greater than the maximum value of the actual thickness of the gasket (4). That is, in this specification, for example, even if the thickness of the gasket (4) before compression is 2mm and the maximum value of the thickness that the gasket (4) can actually have is 2mm, if the maximum value of the axial distance between the bottom surface of the crimping portion (11) and the top surface of the cap (3) is 2.5mm, the first thickness (T1) is defined as 2.5mm. In other words, the dimensions defined by the terms 'first thickness' to 'sixth thickness' in the present invention are dimensions belonging to the remaining structure of the battery can set to allow the gasket (4) to be compressed to a predetermined thickness, and while they 'regulate' the maximum value of the thickness that the gasket (4) can have among certain members, they do not 'define' it. Therefore, cases where the gasket (4) itself has an inappropriate thickness or shrinks and its dimensions become smaller, resulting in it not being properly compressed, may also be included within the range of the battery can according to the present embodiment.

[0109] A third thickness (T3) may be defined as the radial distance between the middle portion (13) and the outer circumference of the cap (3). As described above, the crimping portion (11) may be formed by crimping the end of the side wall (1) after the beading portion (12) is formed first, and then the cap (3) with the gasket (4) fitted thereon is inserted onto the beading portion. At this time, if the outer diameter of the gasket (4) before insertion is excessively large compared to the inner diameter of the side wall (1), the insertion of the cap (3) and the gasket (4) cannot be properly achieved; therefore, the third thickness (T3), defined as the radial distance between the outer circumference of the cap (3) and the inner circumference of the side wall (the middle portion (13)), may be similar to the thickness of the uncompressed gasket (4) before insertion. Therefore, under the assumption that the third thickness (T3) represents the thickness before compression, the degree to which the gasket (4) is compressed can be indicated based on the difference between the first thickness (T1) and the second thickness (T2) and the third thickness (T3).

[0110] In this specification, a first compression ratio and a second compression ratio are defined in relation to a second thickness and a first thickness, respectively. Specifically, the first compression ratio is defined as the ratio of the difference between the third thickness (T3) and the first thickness (T1) to the third thickness (T3), and the second compression ratio is defined as the ratio of the difference between the third thickness (T3) and the second thickness (T2) to the third thickness (T3). That is, the first compression ratio is defined as '1-T1 / T3', and the second compression ratio is defined as '1-T2 / T3'.

[0111] The crimping angle (A) can be defined as the angle formed by the first bottom part (111) and the pressure part (112). At this time, the angle formed by the first bottom part (111) and the pressure part (112) refers to the angle formed in the radial direction by a virtual line segment connecting the boundary between the first bottom part (111) and the pressure part (112) and the tip of the pressure part (112), that is, the angle formed by the average slope of the pressure part (112).

[0112] FIG. 7 shows the amount of moisture ingress according to the setting of the crimping angle, compression ratio, and thickness ratio of the embodiments and comparative examples. In the first comparative example (C1), second comparative example (C2), first embodiment (E1), and second embodiment (E2) of the present invention, the amount of moisture ingress was measured by placing a desiccant inside the battery can and leaving it in a humid environment for a certain period of time, and then measuring the increase in weight of the desiccant, under conditions where the crimping angle (A), the ratio of the second thickness (T2) to the first thickness (T1) (T2 / T1), the first compression ratio (1-T1 / T3), and the second compression ratio (1-T2 / T3) were set differently from each other.

[0113] Referring to FIGS. 6 and 7 together, in the embodiments (E1, E2) of the present invention, the ratio (T2 / T1) of the second thickness (T2) to the first thickness (T1) is set to 0.7 or higher. This reduces the gap between the maximum and minimum axial distances between the crimping portion (11) and the cap (3) compared to the conventional method. That is, if the difference between the first thickness (T1) and the second thickness (T2) is large, the crimping portion (11) receives an excessive reaction force at its leading edge, and consequently, the bending portion rises, increasing the likelihood of forming a gap (V) as shown in FIG. 3. To prevent this, it is necessary to make the degree of compression of the gasket (4) as uniform as possible between the crimping portion (11) and the cap (3).

[0114] At this time, the thickness of the gasket (4) within the section compressed between the crimping portion (11) and the cap (3) and between the beading portion (12) and the cap (3) may be greater than or equal to the second thickness (T2) and less than or equal to the first thickness (T1). Accordingly, the gasket (4) may not have a thickness less than 0.7 times the thickness at any point between a part of the side wall (1) and the cap (3). In this case, the gasket (4) can be compressed uniformly over the entire section to form a long and stable sealing path.

[0115] Here, in order to reliably reduce the possibility of the above voids occurring, it is preferable that the ratio (T2 / T1) be 0.8 or higher.

[0116] According to the first embodiment (E1) of the present invention, the ratio (T2 / T1) was set to 0.89. At this time, the amount of moisture penetration was 0.021g, so almost no moisture penetrated.

[0117] According to the second embodiment (E2) of the present invention, the ratio (T2 / T1) was set to 0.74. At this time, the amount of moisture penetration was 0.029g. This is a higher value than in the first embodiment, but it is a value that can be evaluated as having almost no moisture penetration.

[0118] Meanwhile, it can be seen that in the embodiments (E1, E2), the ratio (T2 / T1) is set to 0.95 or less. According to the first comparative example (C1) of the present invention, in which the ratio (T2 / T1) is set to 1, the amount of moisture penetration was measured to be 0.079g, which is very high. This is because, in order to make the first thickness (T1) and the second thickness (T2) exactly the same, the degree of bending of the crimping portion (11) is insufficient, so the gasket (4) is not sufficiently compressed. That is, in order to enjoy the sealing effect resulting from the compression of the gasket (4), the second thickness (T2) must be at least smaller than the first thickness (T1), and it is preferable that the ratio (T2 / T1) be set to 0.95 or less.

[0119] More preferably, the ratio (T2 / T1) may be 0.9 or less. In order for the gasket (4) to sufficiently exert a sealing effect, it is preferable that the maximum compression ratio of the gasket (4) be 0.1 or more. To ensure that the maximum compression ratio of the gasket (4) is 0.1 or more, the ratio (T2 / T1) must not exceed 0.9. However, the ratio (T2 / T1) is not limited thereto and may have a value between 0.9 and 0.95.

[0120] According to the second comparative example (C2), in which the ratio (T2 / T1) was set to 0.45, the amount of moisture penetration was 0.052g, which was significantly higher than in the second embodiment (E2), in which the ratio (T2 / T1) was set to 0.74. In other test results including these data, it was observed that when the ratio (T2 / T1) was lower than 0.7, the amount of moisture penetration increased significantly.

[0121] Meanwhile, between the cap (3) and the crimping portion (11), it is preferable that the first compression ratio (1-T1 / T3) be greater than 0. In other words, it is preferable that the gasket (4) be in a compressed state at least compared to the third thickness at all points between the cap (3) and the crimping portion (11). If the gasket (4) has a point that is not compressed between the cap (3) and the crimping portion (11), a void may occur at that point, or even if no void occurs, that point may become a weak point in the seal.

[0122] It is preferable that the first compression ratio (1-T1 / T3) be 0.05 or higher. The first compression ratio (1-T1 / T3) may be reduced in both cases where the degree of bending of the crimping portion (11) is excessively small and excessively large. In the first comparative example (C1), in which the degree of bending of the crimping portion (11) is insufficient and the first compression ratio (1-T1 / T3) is set to 0, and in the second comparative example (C2), in which the degree of bending of the crimping portion (11) is excessive and the first compression ratio (1-T1 / T3) is set to -0.1, the amount of moisture penetration was found to be very high at 0.079g and 0.052g, respectively; however, in the first embodiment (E1) and second embodiment (E2) of the present invention, in which the first compression ratio (1-T1 / T3) is set to 0.1 and 0.05, respectively, the amount of moisture penetration was found to be low at 0.021g and 0.029g, respectively.

[0123] It is preferable that the second compression ratio (1-T2 / T3) between the cap (3) and the crimping portion (11) be 0.3 or less. If the second compression ratio (1-T2 / T3) is excessively large, the reaction force applied by the gasket (4) to the tip of the crimping portion (11) becomes excessive, and as a result, the bent portion of the crimping portion (11) rises, causing a void to form. In fact, according to the second comparative example (C2) in which the second compression ratio (1-T2 / T3) is set to 0.55, the first compression ratio (1-T1 / T3) has a negative value of -0.1, which suggests the occurrence of a void.

[0124] It is preferable that the second compression ratio (1-T2 / T3) be 0.1 or greater. This is because the sealing effect of the gasket (4) can be properly exerted only if the compression ratio of the gasket (4) is 0.1 or greater at least at one point between the cap (3) and the crimping portion (11). If the second compression ratio (1-T2 / T3) is less than 0.1, the sealing effect is not properly exerted, no matter how small the difference between the second compression ratio (1-T2 / T3) and the first compression ratio (1-T1 / T3) is.

[0125] The above experimental results indicate a difference in sealing force based on the ratio of the maximum and minimum axial distances within the overlapping section between the crimping portion (11) and the cap (3). However, in relation to the meaning of the ratio of the upper and lower limits of the thickness at which the gasket (4) is compressed, this can be applied by analogy to other parts sealed by the gasket (4). That is, even between the bottom surface of the cap (3) and the top surface of the beading portion (12), if there are points on the gasket (4) that have a thickness ratio differing by more than the first thickness (T1) and the second thickness (T2), this causes deformation of the side wall (1) and / or the cap (3), and consequently, a void may be formed or the sealing force may be weakened. Accordingly, according to one embodiment of the present invention, in the section where the gasket (4) is interposed between the beading portion (12) and the cap (3), the axial distance between the beading portion (12) and the cap (3) is set to be greater than the first thickness (T1) and less than the second thickness (T2), thereby allowing the gasket (4) to be uniformly compressed and preventing deformation of the beading portion (12) and the cap (3), thereby minimizing the occurrence of voids and strengthening the sealing force.

[0126] In the embodiments (E1, E2) of the present invention, the crimping angle (A) is set to be greater than 0 degrees and less than 5 degrees. If the crimping angle (A) is too small (0 degrees or less), the crimping portion (11) cannot sufficiently press the gasket (4), and thus the gasket (4) cannot exert a sealing effect. Also, if the crimping angle (A) is too large (5 degrees or more), a gap may occur between the first bend portion and the gasket (4), and the gap may become a weak point in the seal.

[0127] In each of the first comparative example (C1), second comparative example (C2), first embodiment (E1), and second embodiment (E2) of the present invention, the crimping angle (A) was set to 0 degrees, 7.5 degrees, 2 degrees, and 4.5 degrees.

[0128] In the first comparative example (C1), the gasket (4) was hardly compressed, so a high moisture penetration amount of 0.079g was measured. In the second comparative example (C2), the first bottom part and the first folded part rose due to the excessive reaction force applied to the pressurized part, so a high moisture penetration amount of 0.052g was measured.

[0129] In contrast, according to the first embodiment (E1) and the second embodiment (E2) in which the crimping angle (A) was appropriately set, the amount of moisture penetration was measured to be significantly lower at 0.021g and 0.029g, respectively, and no voids occurred.

[0130] More preferably, the crimping angle (A) may be 4.5 degrees or less. When the crimping angle (A) is set to be greater than 4.5, the amount of moisture penetration is measured to be greater than 0.03g.

[0131] Additionally, preferably, the crimping angle (A) may be 2 degrees or more. When the crimping angle (A) is less than 2 degrees, the minimum compression ratio of the gasket (4) becomes less than 0.1, resulting in a weak seal.

[0132] Referring again to FIG. 6, the pressurizing part (112) according to one embodiment of the present invention may have an upwardly convex shape in which the slope decreases along the radial inner direction. This may mean that the slope at the tip of the pressurizing part (112) is greater than the slope of the crimping angle (A). This may be the result of deformation occurring radially outward during the formation process of the crimping part (11). As crimping is performed not only axially inward but also radially outward in this way, the gasket (4) may be prevented from being pushed out radially inward. In addition, in this case, as the gasket (4) receives a force pushing it toward the middle part (13), it is compressed toward the first bending part (110) and the middle part (13), allowing it to be more closely attached to the area vulnerable to the occurrence of a void.

[0133] FIG. 8 shows a gasket according to one embodiment being compressed axially and adhering to the cap and the middle section. Hereinafter, with reference to FIG. 6, the action of strengthening the sealing force as the gasket passing through the middle section is compressed axially and the structure of the battery can according to one embodiment for this purpose will be explained.

[0134] The first bottom portion (111) may be located radially inward relative to the radially outer end of the cap (3). This means that if the first bottom portion (111) extends over a predetermined section, the entire predetermined section is located radially inward relative to the radially outer end of the cap (3). In other words, the first bend portion (110) may extend radially inward relative to the radially outer end of the cap (3). Accordingly, the portion of the gasket (4) passing through the middle portion (13) receives an axially compressive force.

[0135] The second bend portion (120) may extend radially inward relative to the radially outer end of the cap (3). Accordingly, the portion of the gasket (4) passing through the middle portion (13) receives an axially compressive force.

[0136] According to one embodiment of the present invention, as both the first bend portion (110) and the second bend portion (120) extend radially inward relative to the radially outer end of the cap (3), the entire portion of the gasket (4) passing through the middle portion (13) is axially interposed between the first bend portion (110) and the second bend portion (120), and as a result of the maximum axial distance between the first bend portion (110) and the second bend portion (120) decreasing as it moves radially outward, the gasket (4) is compressed axially at the point where it passes through the middle portion (13).

[0137] Independently thereof, when the maximum value of the radial distance between the side wall (1) and the outer periphery of the cap (3) defines the third thickness (T3) and the minimum distance between the radially outer end of the cap (3) and the crimping portion (11) defines the fourth thickness (T4), the fourth thickness (T4) may be greater than or equal to the second thickness (T2) and less than the third thickness (T3). If the fourth thickness (T4) is smaller than the second thickness (T2), the gasket (4) may be excessively compressed and damaged, and if it is larger than the third thickness (T3), the gasket (4) may not be properly compressed, resulting in a void or a weakened sealing force.

[0138] The above fourth thickness (T4) may be less than the above first thickness (T1). Accordingly, the gasket (4) may be compressed more axially by the first bend portion (110) than by the first bottom portion (111).

[0139] Referring to FIG. 8, when the gasket (4) is compressed axially in the section passing through the intermediate section (13) as in the configurations described above, the corresponding section of the gasket (4) undergoes deformation in which the axial cross-sectional area expands due to the Poisson effect. This deformation prevents the sealing force from being weak in the section passing through the intermediate section (13) or the occurrence of a gap (V) as in FIG. 3, as there is no way to compress the gasket (4) radially. That is, unlike other sections where sealing is achieved by compressing the gasket (4) by narrowing the space between the side wall (1) and the cap (3), sealing is achieved in the outer periphery of the cap (3) and the intermediate section (13) by expanding the cross-sectional area of ​​the gasket (4) while maintaining the distance between the cap (3) and the intermediate section (13).

[0140] FIGS. 9 and 10 illustrate the presence or absence of bending load applied to the cap depending on the degree of extension of the beading portion. Referring to these figures together with FIG. 6 below, the beading portion (12) according to one embodiment may be extended radially inward beyond the radially inner end of the crimping portion (11). As the crimping portion (11) is formed, the gasket (4) and the cap (3) receive axial inward pressure distributed in the section overlapping with the crimping portion (11). At this time, as shown in FIG. 9, if the beading portion (12) fails to provide a reaction force in the entire section where the gasket (4) and the cap (3) receive pressure from the crimping portion (11), the positions of the resultant force received by the gasket (4) and the cap (3) from the crimping portion (11) and the resultant force received from the beading portion (12) are radially misaligned, resulting in a bending load. Accordingly, the gasket (4) may be subjected to an excessively uneven compressive force, or bending deformation may occur in the cap (3), forming a void or making the structure unstable. Accordingly, by setting the beading portion (12) to extend radially inward at least further than the crimping portion (11), a reaction force against the pressure provided by the crimping portion (11) can be provided throughout the entire section as shown in FIG. 10, and unnecessary load or deformation can be prevented.

[0141] Specifically, the section of the gasket (4) supported by the beading portion (12) may extend radially inward beyond the radially inner end of the crimping portion (11). Here, the statement that the gasket (4) is supported by the beading portion (12) means a section in which the gasket (4) is compressed to transmit the reaction force provided by the beading portion (12) against the pressure applied by the crimping portion (11) to the cap (3) along the thickness direction, thereby exerting an elastic restoring force, when the direction perpendicular to the extension direction of the gasket (4) (or the tangential direction at a point on the gasket (4)) is defined as the thickness direction of the gasket (4). This may be defined, for example, as a section in which the gasket (4) contacts the bottom surface of the cap (3), or as a section in which the gasket (4) is interposed in the thickness direction between the cap (3) and the beading portion (12) or is elastically compressed. In other words, the section where the reaction force provided by the beading section (12) against the pressure applied by the crimping section (11) to the cap (3) is transmitted to the cap (3) through the gasket (4) can be extended beyond the radially inner end of the crimping section (11). Accordingly, unnecessary or unbalanced loads on the cap (3) and the gasket (4) can be prevented.

[0142] FIG. 11 shows the shape of a current collector plate according to one embodiment, and FIG. 12 shows a portion in which a current collector plate is interposed between a beading portion and a cap in a battery can according to one embodiment. Referring to these drawings, a current collector plate (5) may be interposed between the gasket (4) and the beading portion (12). The current collector plate (5) may be electrically connected to the electrode assembly to connect the electrode assembly accommodated in the battery can to the terminal, but regardless of its name, as long as it is a plate-shaped member interposed between the gasket (4) and the beading portion (12), it may refer to anything regardless of its exact function and operation.

[0143] At this time, the collector plate (5) may be extended further inward in the radial direction relative to the gasket (4). Since the collector plate (5) is extended inward in the radial direction relative to the gasket (4) and is interposed between the beading portion (12) and the gasket (4), it can provide a reaction force against the axial load applied by the crimping portion (11) to the gasket (4) throughout the entire section. As such, since a reaction force parallel without staggering is provided against the axial load applied by the crimping portion (11) to the gasket (4) and through it to the cap (3), unnecessary load or deformation is prevented from being applied to the gasket (4) and the cap (3).

[0144] In the battery can according to one embodiment of the present invention, the current collector plate (5) may be arranged along the circumferential direction in sections interposed between the gasket (4) and the beading portion (12) and sections not interposed. At this time, the current collector plate (5) may have a shape having a wing portion (50) that is spaced apart along the circumferential direction as in the embodiment shown in FIG. 11 and has at least a portion of each of the wing portions overlapping with the region (I) where the gasket (4) and the beading portion (12) are provided, but the specific shape of the current collector plate (5) is not limited thereto.

[0145] Here, as shown in FIG. 6, in the section where the current collector plate (5) is not interposed between the gasket (4) and the beading section (12), the fifth thickness (T5) is defined as the minimum value of the axial distance between the beading section (12) and the cap (3), and as shown in FIG. 12, in the section where the current collector plate (5) is interposed between the gasket (4) and the beading section (12), the sixth thickness (T6) is defined as the minimum value of the axial distance between the current collector plate (5) and the cap (3), and the fifth thickness (T5) and the sixth thickness (T6) may be greater than or equal to the second thickness (T2) and less than or equal to the first thickness (T1). Since it is very difficult to mold the gasket (4) such that it has different thicknesses in the area where the current collector plate (5) is interposed between the beading portion (12) and the gasket (4) and in the area where it is not interposed, by controlling the fifth thickness (T5) and the sixth thickness (T6) to be within the range of the second thickness (T2) or greater and the first thickness (T1) or less, the degree of compression of the gasket (4) can be prevented from becoming excessively uneven despite changes in dimensions along the circumferential direction.

[0146] FIG. 13 is an enlarged view of the main part of FIG. 5, showing different numerical values ​​than FIG. 6. By referring to this, a first length () can be defined as the radial length of the section where the crimping part (11) and the cap (3) overlap in the axial direction. At this time, the first length () can be set to be at least twice the second thickness (T2) and the first thickness (T1). If the first length () is less than twice the second thickness (T2), the bending angle of the crimping part (11) becomes steeper than 5 degrees to secure an appropriate minimum compression rate of the gasket (4), and it was confirmed that there is a high possibility of a void occurring accordingly. In addition, if the first length () is shorter than twice the first thickness (T1), the length relative to the cross-sectional area of ​​the sealing path becomes excessively small, making it easier for moisture to penetrate, and if crimping is applied more strongly to prevent this, deformation due to uneven reaction force and the resulting formation of voids become easier.

[0147] When the maximum value of the radial distance between the middle portion (13) and the outer periphery of the cap (3) defines the third thickness (T3), the thickness (Tc) of the cap (3) may be less than or equal to the third thickness (T3). When considering the shape of a cross-section (CS) formed by cutting the gasket (4) like a cake in an axial section equal to the thickness (Tc) of the cap (3), if the thickness (Tc) of the cap (3) is greater than the third thickness (T3), the shape of the cross-section (CS) is formed to be excessively slender, so that linear Poisson deformation with respect to compression does not occur, and unintended deformations such as buckling or shear deformation occur, which may result in weak or uneven adhesion, or voids may occur. Accordingly, by setting the thickness of the cap (3) to be less than or equal to the third thickness (T3) so that the portion passing between the middle portion (13) and the outer portion of the cap (3) in the gasket (4) has a square cross-section or a cross-section that is larger in the radial direction than in the axial direction, the portion can be made to undergo linear Poisson deformation with respect to axial compression.

[0148] The gasket (4) may include an exposed portion (40) that protrudes radially inward relative to the radially inner end of the crimping portion (11). In this way, as the gasket (4) protrudes outward relative to the crimping portion (11), a portion of the gasket (4) can be compressed to an intended thickness between the tip of the crimping portion (11) and the cap (3). At this time, a second length () may be defined as the length to which the exposed portion (40) protrudes.

[0149] When the first length () is defined as the radial length of the section where the crimping portion (11) and the cap (3) overlap in the axial direction, the second length () may be less than or equal to half of the first length (). Additionally, independently of this, the second length () may be less than or equal to twice the second thickness (T2). If the second length () is set to an excessively long length, the risk of deformation or load received by the exposed portion (40), which is not directly supported by other members including the crimping portion (11), being transferred to the remaining parts of the gasket (4) participating in the sealing increases, thereby lowering the stability of the seal. Furthermore, if the second length () is too long, the exposed portion (40) is prone to being bent or lifted, and at this time, seepage of moisture may occur through the gap between the exposed portion (40) and the crimping portion (11) and / or between the exposed portion (40) and the cap (3). Accordingly, by setting the upper limit of the second length () as above, such a decrease in sealing power can be prevented.

[0150] The embodiments described above should be understood as exemplary in all respects and not limiting, and the scope of the invention will be defined by the claims set forth below rather than by the detailed description above. Furthermore, the meaning and scope of the claims set forth below, as well as all modifications and variations derived from equivalents thereof, should be interpreted as being included within the scope of the invention.

[0151] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. A side wall extending axially with an annular cross-section; An opening defined by the axial outer end of the above-mentioned side wall; A crimping portion formed by bending the axial outer end of the above-mentioned side wall inward in the radial direction; A beading portion formed by inwardly sinking a portion spaced downward from the crimping portion on the above side wall by a predetermined gap; An intermediate portion extending axially from the above side wall and connecting the crimping portion and the beading portion; A cap supported by the side wall to cover the opening; and A gasket compressed and interposed between a part of the side wall including the crimping portion and the beading portion and the cap; comprising The maximum and minimum values ​​of the axial distance between the bottom surface of the crimping portion and the top surface of the cap each define the first thickness and the second thickness, respectively, and A battery can in which the ratio (T2 / T1) of the second thickness (T2) to the first thickness (T1) is 0.7 or greater.

2. A battery can according to claim 1, wherein the thickness of the gasket in the section compressed and interposed between the crimping portion and the cap and between the beading portion and the cap is greater than or equal to the second thickness and less than or equal to the first thickness.

3. A battery can according to claim 1, wherein the ratio (T2 / T1) of the second thickness (T2) to the first thickness (T1) is 0.8 or greater.

4. A battery can according to claim 1, wherein the ratio (T2 / T1) of the second thickness (T2) to the first thickness (T1) is 0.95 or less.

5. A battery can according to claim 1, wherein the ratio (T2 / T1) of the second thickness (T2) to the first thickness (T1) is 0.9 or less.

6. In claim 1, the maximum value of the radial distance between the side wall and the outer periphery of the cap defines the third thickness, and A battery can, wherein the first compression ratio (1-T1 / T3), defined as the ratio of the difference between the third thickness (T3) and the first thickness (T1) with respect to the third thickness (T3), is greater than 0.

7. A battery can according to claim 6, wherein the first compression ratio is 0.05 or higher.

8. In claim 1, the maximum value of the radial distance between the side wall and the outer periphery of the cap defines the third thickness, and A battery can in which the second compression ratio (1-T2 / T3), defined as the ratio of the difference between the third thickness (T3) and the second thickness (T2) with respect to the third thickness (T3), is 0.3 or less.

9. A battery can according to claim 8, wherein the second compression ratio is 0.1 or greater.

10. In claim 1, the crimping portion comprises: A first bent portion extending from the above intermediate portion and bent such that the slope gradually decreases along the radial inner direction; A pressure member inclined to have a negative slope with respect to the radial inner direction; and It includes a first bottom portion defined as a region between the first bending portion and the pressing portion where the inclination with respect to the radial direction is 0; A battery can, wherein the first thickness corresponds to the axial distance between the cap and the first bottom portion.

11. A battery can according to claim 10, wherein the crimping angle defined as the angle formed by the pressurizing part with the radial direction is greater than 0 degrees and less than 5 degrees.

12. A battery can according to claim 11, wherein the crimping angle is 2 degrees or more and 4.5 degrees or less.

13. A battery can according to claim 11, wherein the pressurizing part has an upwardly convex shape in which the slope decreases along the radial inner direction.

14. A battery can according to claim 10, wherein the first bottom portion is located radially inward relative to the radially outer end of the cap.

15. In claim 14, the beading portion includes a second bent portion that extends from the intermediate portion and is bent such that the negative slope gradually decreases along the radial inner direction, and A battery can, wherein the second bend portion extends radially inward relative to the radially outer end of the cap.

16. In claim 1, the maximum value of the radial distance between the side wall and the outer periphery of the cap defines the third thickness, and When the minimum distance between the radially outer end of the above cap and the crimping portion defines the fourth thickness, A battery can, wherein the fourth thickness is greater than or equal to the second thickness and less than the third thickness.

17. A battery can according to claim 16, wherein the fourth thickness is less than the first thickness.

18. A battery can according to claim 1, wherein the beading portion extends radially inward beyond the radially inner end of the crimping portion.

19. A battery can according to claim 1, wherein the section supported by the beading portion in the gasket extends further radially inward beyond the radially inner end of the crimping portion.

20. In claim 1, a current collector plate is interposed between the gasket and the beading portion, and The above current collector plate is a battery can that extends further inward in the radial direction compared to the above gasket.

21. In claim 20, the current collector plate is arranged along the circumferential direction in sections interposed between the gasket and the beading portion and sections not interposed, and In the section where the above current collector plate is not interposed between the gasket and the beading portion, the fifth thickness is defined as the minimum value of the axial distance between the beading portion and the cap, and When the sixth thickness is defined as the minimum value of the axial distance between the current collector plate and the cap in the section where the current collector plate is interposed between the gasket and the beading portion, A battery can in which the fifth thickness and the sixth thickness are greater than or equal to the second thickness and less than or equal to the first thickness.

22. A battery can according to claim 1, wherein the first length, defined as the radial length of the section where the crimping portion and the cap overlap in the axial direction, is at least twice the second thickness.

23. A battery can according to claim 22, wherein the first length, defined as the radial length of the section where the crimping portion and the cap overlap in the axial direction, is at least twice the first thickness.

24. In claim 1, the maximum value of the radial distance between the intermediate portion and the outer periphery of the cap defines the third thickness, and A battery can in which the thickness of the cap is less than or equal to the third thickness.

25. In claim 1, the gasket comprises an exposed portion that protrudes radially inward relative to the radially inner end of the crimping portion, and A first length is defined as the radial length of the section where the crimping portion and the cap overlap in the axial direction, and A battery can, wherein the second length, defined as the length of the protruding extension of the above-mentioned exposed portion, is less than or equal to half of the first length.

26. In claim 1, the gasket comprises an exposed portion that extends radially inward relative to the radially inner end of the crimping portion, and A battery can, wherein the second length, defined as the length of the protruding extension of the above-mentioned exposed portion, is less than or equal to twice the second thickness.

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