Bent battery cell

Abstract

The present invention relates to a battery cell having a curved cross section, in which both side sealing portions of the battery case are sealed with UV glue coating based on the direction in which the electrode leads are formed, and a cut portion is formed in the center of each of the both side sealing portions in the longitudinal direction.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0149600 dated November 3, 2021 and Korean Patent Application No. 10-2022-0144340 dated November 2, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a curved shaped battery cell. [Background technology]

[0003] Along with technological development and increasing demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing. Among such secondary batteries, lithium secondary batteries, which exhibit high energy density and working potential, long cycle life, and low self-discharge rate, have been commercialized and are widely used.

[0004] Recently, the design of electronic devices itself has become a very important factor in consumers' product selection, and electronic devices are becoming smaller and thinner according to consumer preferences. Accordingly, lithium secondary batteries are also required to be smaller and thinner in order to minimize the waste of the internal space of electronic devices, and the shape of lithium secondary batteries needs to be diversified according to the shape of electronic devices. Recently, there has been an increasing demand for curved batteries, including flexible batteries.

[0005] On the other hand, secondary batteries are classified into cylindrical or rectangular secondary batteries that use a metal can, and pouch-type batteries that use a pouch-type secondary battery case made of a laminate sheet, depending on the battery case. Here, pouch-type secondary batteries are used in the flexible batteries because they are easily deformed.

[0006] Such a pouch-type secondary battery is manufactured by sealing the opening with an electrode assembly housed in a battery case, and has a structure having a cross-section curved based on the direction in which the electrode leads extend, and sealing portions on both sides where the electrode leads do not protrude based on the direction in which the electrode leads extend are bent toward the battery cell.

[0007] At this time, when the sealing portions on both sides are bent, the width of the sealing on both sides is not uniform due to the curved shape of the battery cell, so a specific sealing width cannot be ensured.

[0008] In addition, in general, in the process of housing an electrode assembly in a pouch-type battery case made of a laminate sheet, injecting an electrolyte solution, and sealing the case by heat sealing or the like, the heat-sealed portion (sealing portion) is easily contaminated during the electrolyte injection process, and the innermost resin layer of the laminate sheet melts excessively, and / or the inner resin layer protrudes outward due to pressure. As a result, moisture easily penetrates the pouch-type secondary battery, which may result in leakage of the electrolyte solution.

[0009] Therefore, there is a pressing need to develop battery cell technology that can solve these problems. Summary of the Invention [Problem to be solved by the invention]

[0010] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS The present invention provides a battery cell that can solve the problem of uneven sealing width or electrolyte leakage that may occur at the sealing portions on both sides of a curved battery cell. [Means for solving the problem]

[0011] A battery cell according to an embodiment of the present invention includes: A battery cell having a curved cross section, Based on the direction in which the electrode leads are formed, both side sealing parts of the battery case are sealed by UV glue coating, and a cutting part is formed in the center in the longitudinal direction from each of the both side sealing parts.

[0012] Here, the battery cell may be formed so that a cross section of the battery cell in a direction in which the electrode leads are formed has a curve in which both side ends are curved in the same direction relative to a center.

[0013] In this case, the radius of curvature (R) of the curve of the battery cell may be 90 mm to 100 mm.

[0014] On the other hand, the battery case may be a pouch-type battery case made of a laminate sheet including a resin layer and a metal layer.

[0015] In addition, both side sealing portions of the battery case may be bent toward the battery cells.

[0016] Meanwhile, the cut portions formed on the both side sealing portions may be formed within a point that is 1 / 3 to 2 / 3 of the total length of the both side sealing portions in the direction in which the electrode lead is formed, and the cut portions may be cut in an inward direction from the outer ends of the both side sealing portions toward the storage portion of the battery case so that stress due to the curve of the battery cell is not concentrated in the center, and more specifically, the cut portions may be formed in a straight line or V shape.

[0017] The cut portions may be formed to a depth of 10% to 70% based on a sealing width from the outer ends of the side sealing portions toward the housing portion of the battery case.

[0018] Furthermore, a UV glue coating may additionally be formed on the cutting surface of the cutting portion.

[0019] The UV glue coating formed on the surface of the cutting part by sealing both side sealing parts may be a cured ultraviolet (UV) curable material, and in this case, the UV curable material may include one or more materials selected from the group consisting of unsaturated polyester-based materials, polyester acrylates, epoxy acrylates, and urethane acrylates.

[0020] According to another embodiment of the present invention, the present invention also provides a battery module including the battery cell. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a perspective view of a battery cell according to one embodiment of the present invention. [Diagram 2] 2 is a perspective view of the battery cell of FIG. 1 before one side sealing portion is folded. FIG. [Diagram 3] 2 is a cross-sectional view of the sealing portions on both side surfaces of the battery cell in FIG. 1. [Figure 4] This is a photo of the battery cell before the curved side sealing parts are folded, sealed with UV glue coating. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The terms and words used in the present specification and claims should not be interpreted in their ordinary and dictionary sense, but should be interpreted in the sense and concept that corresponds to the technical idea of ​​the present invention, in accordance with the principle that the inventor can appropriately define the concept of the term in order to explain his / her invention in the best possible way. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only preferred embodiments of the present invention, and do not represent all of the technical ideas of the present invention, so there may be various equivalents and modifications that can replace them at the time of filing this application, and the scope of the present invention is not limited to the embodiments described below.

[0023] The present invention will now be described in detail with reference to the drawings. The terms and words used in the present specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as having meanings and concepts that correspond to the technical ideas of the present invention, in accordance with the principle that the inventor can appropriately define the concepts of terms in order to best describe his / her invention.

[0024] Furthermore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and therefore there may be various equivalents and modifications that can replace them at the time of this application.

[0025] According to one embodiment, the present invention provides a battery cell having a curved cross section, Based on the direction in which the electrode leads are formed, both side sealing parts of the battery case are sealed by UV glue coating, and a battery cell is provided in which a cutting part is formed in the center in the longitudinal direction from each of the both side sealing parts.

[0026] FIG. 1 shows a perspective view of a battery cell 100 according to one embodiment of the present invention.

[0027] 1, the battery cell 100 has a curved cross section. In this case, the cross section of the battery cell 100 in the direction in which the electrode leads 101 are formed is curved such that both end portions are curved in the same direction with respect to a central axis A. Of course, the drawing shows a curved shape based on the center, but the curved part does not have to be the center, and is not limited to this as long as both end portions are curved around a certain reference axis.

[0028] In this case, the radius of curvature (R) of the curve of the battery cell 100 may be 90 mm to 100 mm.

[0029] When formed within the radius of curvature, the safety of the battery cell 100 can be ensured and the battery cell 100 can be used as a flexible battery in a curved shape.

[0030] Meanwhile, the battery cell 100 has a structure in which an electrode assembly is housed in a battery case 110 together with an electrolyte.

[0031] In this case, the battery case 110 may be a pouch-type battery case made of a laminate sheet including a resin layer and a metal layer. Specifically, the laminate sheet may be an aluminum laminate sheet.

[0032] Meanwhile, the battery case 110 has sealing parts at the side where the electrode leads are formed and at both sides thereof. At this time, the sealing parts 111 and 112 at both sides are bent toward the battery cells 100.

[0033] However, when bending both side sealing parts of a curved battery cell, the width of both side sealing parts may not be uniform due to the curved shape, and may not be sufficient.

[0034] This causes problems such as electrolyte leakage or moisture intrusion in areas where it is difficult to maintain a sufficient sealing state.

[0035] Therefore, in order to solve this problem, the present invention has a structure in which the sealing parts on both sides are sealed by UV glue coating.

[0036] To explain this structure in more detail, FIG. 2 shows a schematic diagram of the battery cell of FIG. 1 before one side sealing portion 112 is folded toward the battery cell 100, FIG. 3 shows a schematic cross-sectional view of one of such side sealing portions 111, 112, and FIG. 4 shows a photograph of a battery cell in which both side sealing portions have been UV glue coated.

[0037] 2 to 4, both side sealing parts 111 and 112 are sealed by a UV glue coating 114a that bonds the side sealing part 116 of the upper case and the side sealing part 117 of the lower case using a UV glue rather than a typical sealing such as thermal bonding.

[0038] In this way, when sealing is performed using the UV glue coating 114a, not only can electrolyte leakage and moisture intrusion be prevented, but the problem of Al of the battery case 110 being exposed can also be improved. Since the sealing strength is increased, the bending parts of the sealing parts 111 and 112 on both sides can be minimized, and the capacity can also be increased.

[0039] Meanwhile, referring again to Figures 1 to 3, the curved battery cell 100 of the present invention has cutting portions 113 formed in both side sealing portions 111, 112 so as to ensure the sealing width of both side sealing portions 111, 112 and to make the curves in both side sealing portions 111, 112 natural.

[0040] When a cutting portion is formed as in the present invention in the case of sealing by a general heat fusion method that has been used in the past, the sealing is not performed sufficiently at both side sealing portions, and the safety problem of electrolyte leakage or moisture intrusion becomes more serious.

[0041] However, according to the present invention, this problem can be solved by sealing both side sealing parts 111 and 112 with a UV glue coating 114a.

[0042] Therefore, in the present invention, the cutting portion 113 for securing the sealing width can be formed in the sealing portions 111 and 112 on both sides without worrying about electrolyte leakage or moisture intrusion.

[0043] In this case, the cutting portion 113 may be formed within a point that is 1 / 3 to 2 / 3 of the total length 1 of the battery cell 100 in the direction in which the electrode lead 101 is formed, more specifically, within a point that is 2 / 5 to 3 / 5 of the middle portion, and even more specifically, may be formed at a point that is 1 / 2 based on the drawing, in other words, at a position corresponding to the curved central axis A of the battery cell 100.

[0044] Therefore, by forming the cut portion 113 at a position corresponding to the curved central axis A, it is possible to relieve to some extent the concentration of stress on the curved portion, that is, the center of curvature, which is preferable.

[0045] In addition, the cut portions 113 are cut inward from the outer ends of the side sealing portions 111 and 112 toward the storage portion 115 of the battery case 110 so that stress due to the curve of the battery cell 100 is not concentrated in the center.

[0046] At this time, the shape of the cutting portion 113 is not limited and may be an amorphous shape such as a straight curve, but it is most preferable that the cutting portion 113 be formed in a straight or V shape, more specifically a V shape, in order to ensure the sealing width of both sides and realize the curved shape while preventing the stress caused by the curve of the battery cell 100 from concentrating in the center and resolving this. At this time, the V shape is formed in the opposite direction to the curved direction, i.e., the apex direction faces downward when both side sealing portions 111, 112 are bent toward the battery cell 100.

[0047] In addition, the cutting portion 113 may be formed to a depth of 10% to 70% of the sealing width from the outer ends of both side sealing portions 111 and 112 toward the storage portion 115 of the battery case 110, more specifically, a depth of 30% to 70%, and more specifically, a depth of 30% to 60%.

[0048] If the depth of the cutting portion 113 is too small outside the above range, the effect obtained by forming the cutting portion 113 cannot be fully exerted, and if the depth is too deep, there is a possibility of electrolyte leakage or moisture intrusion despite the UV glue coating 114a, which is not preferable.

[0049] Furthermore, a UV glue coating 114b may additionally be formed on the cutting surface of the cutting portion 113.

[0050] In this case, even when cutting the cutting portion 113 after sealing the sealing portions 111 and 112 on both sides, the possibility of electrolyte leakage or moisture intrusion can be significantly reduced.

[0051] If the UV glue coating 114b is additionally formed after the cutting portion 113 is formed, the problem of the aluminum of the laminate sheet being exposed to the outside again due to the formation of the cutting portion 113 can be eliminated. In this case, the UV glue coating may be made of an ultraviolet (UV) curable material, and sealing is performed by such curing.

[0052] At this time, the UV-curable material is a material that exhibits high intermolecular bonding strength while undergoing cross-linking through a chemical reaction when irradiated with UV rays.

[0053] In particular, the UV-curable material may include, for example, one or more materials selected from the group consisting of unsaturated polyester-based materials, polyester acrylates, epoxy acrylates, and urethane acrylates.

[0054] In addition, the ultraviolet curable material may be a material having a hydrophilic functional group. In this case, the ultraviolet curable material can collect moisture that flows into the inside of the battery, thereby increasing the sealing strength of the battery case and simultaneously suppressing the intrusion of moisture.

[0055] The UV-curable material is applied in a high viscosity state to the battery case corresponding to both side sealing parts and then cured to perform sealing. At this time, the UV-curable material is applied in the form of an oligomer or a low molecular weight polymer having a predetermined viscosity.

[0056] Specifically, the ultraviolet curable material may be added in a state where the viscosity is 18,000 mPa·s to 35,000 mPa·s, and more specifically, in a state where the viscosity is 24,000 mPa·s to 29,000 mPa·s.

[0057] That is, the UV-curable material of the present invention is added to the relevant portion in the form of an oligomer or low molecular weight polymer having a viscosity within the above range, so that it is easy to apply and has almost no flow even after application, thereby ensuring sufficient sealing strength.

[0058] In some cases, the UV-curable material may be added to the site in a state where it is injected as a monomer with a thickener added thereto.

[0059] Specifically, the thickener for increasing the viscosity of the ultraviolet curable material may be, for example, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, polyvinylacrylate, etc., and such a thickener may be added to the ultraviolet curable material to increase the viscosity.

[0060] In this way, the curved battery cell according to the present invention can solve the problem of non-uniform sealing width as the sealing parts on both sides are bent according to the curved shape by the cutting parts, and also solves safety issues such as electrolyte leakage or moisture intrusion that may occur due to the formation of the cutting parts by sealing the sealing parts on both sides with UV glue coating and going one step further by additionally coating the cutting surface of the cutting parts with UV glue.

[0061] According to another embodiment of the present invention, the present invention also provides a battery module including the battery cell.

[0062] The manufacturing method and structure of the battery module are well known in the art, so a detailed description thereof will be omitted in this specification.

[0063] Those skilled in the art will appreciate that the present invention can be applied in a variety of ways and modified within the scope of the present invention based on the above content. [Industrial Applicability]

[0064] The curved battery cell according to the present invention has a cut portion formed on both side sealing portions, so that the sealing width of both sides can be secured and made constant. The sealing portions on both sides are sealed with a UV glue coating, and furthermore, a UV glue coating is formed on the cutting surface of the cutting portion, so that problems of electrolyte leakage or moisture intrusion due to the formation of the cut portion can be eliminated, thereby ensuring the safety of the battery.

[0065] In addition, UV glue coating improves the aluminum exposure of the battery case and minimizes the bends in the sealing parts on both sides, thereby increasing capacity.

Claims

1. A battery cell having a curved cross section, Based on a direction in which the electrode leads are formed, both side sealing parts of the battery case are sealed by UV glue coating, and a cutting part is formed at a center part in a longitudinal direction from each of the both side sealing parts, The two side sealing portions are bent toward the battery cell, The cutting surface of the cutting part is additionally coated with UV glue; Battery cell.

2. The battery cell according to claim 1 , wherein the cross section of the battery cell in the direction in which the electrode leads are formed is curved such that both side ends are curved in the same direction relative to a center.

3. The battery cell according to claim 1 , wherein the radius of curvature (R) of the curve of the battery cell is 90 mm to 100 mm.

4. 2. The battery cell according to claim 1, wherein the battery case is a pouch-type battery case made of a laminate sheet including a resin layer and a metal layer.

5. The battery cell according to claim 1 , wherein the cut portion is formed within a point that is ⅓ to ⅔ of the total length of the both side sealing portions in a direction in which the electrode leads are formed.

6. The battery cell according to claim 1 , wherein the cutouts are cut inward from the outer ends of the side sealing parts toward the storage part of the battery case so that stress due to a curve of the battery cell is not concentrated in a center.

7. The battery cell according to claim 6 , wherein the cutout portion is formed in a line shape or a V shape.

8. The battery cell according to claim 6, wherein the cutouts are formed to a depth of 10% to 70% of a sealing width from outer ends of the side sealing parts toward a receiving part of the battery case.

9. The battery cell of claim 1 , wherein the UV glue coating is an ultraviolet (UV) curable material.

10. 10. The battery cell of claim 9, wherein the UV-curable material comprises one or more materials selected from the group consisting of unsaturated polyester-based materials, polyester acrylates, epoxy acrylates, and urethane acrylates.

11. A battery module comprising the battery cell according to claim 1 .

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