Cylindrical battery, battery pack including same, and automobile

Abstract

The present invention discloses a cylindrical battery having a structure that is less susceptible to distortion due to crimping pressure during a crimping process in a battery manufacturing process. The cylindrical battery according to one aspect of the invention includes an electrode assembly having first and second electrode tabs, a battery housing that receives the electrode assembly through an opening formed at its upper end, and a top cap configured to cover the opening and including a folding region that includes a peripheral region, a central region that is located relatively further inward than the peripheral region, and a first folding portion that is located between the peripheral region and the central region and has a downwardly convex folding shape.

Description

[Technical Field]

[0001] The present invention relates to a cylindrical battery, a battery pack including the same, and an automobile, and more particularly to a cylindrical battery having a structure that is less subject to distortion due to crimping pressure during a crimping process in a battery manufacturing process, a battery pack including the same, and an automobile.

[0002] This application claims priority based on Korean Patent Application No. 10-2023-0059395, filed on May 8, 2023, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings thereof. [Background technology]

[0003] Secondary batteries, which have high applicability across a range of products and electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are driven by electrical sources.

[0004] Such secondary batteries have not only the temporary advantage of dramatically reducing the amount of fossil fuel used, but also the advantage of not producing any by-products associated with energy use, and are therefore attracting attention as a new energy source that is environmentally friendly and improves energy efficiency.

[0005] Currently widely used types of secondary batteries include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries. The operating voltage of such a unit secondary battery cell is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, a battery pack may be configured by connecting multiple batteries in series. Furthermore, depending on the charge / discharge capacity required for the battery pack, a battery pack may also be configured by connecting multiple battery cells in parallel. Therefore, the number and electrical connection form of the battery cells included in the battery pack may be variously set depending on the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, known types of secondary battery cells include cylindrical, prismatic, and pouch-type batteries. In the case of cylindrical batteries, a separator, which is an insulator, is sandwiched between a positive electrode and a negative electrode and wound up to form a jelly-roll-type electrode assembly, which is then inserted into a battery housing together with an electrolyte. A crimping process is then performed in which one end of the top of the battery housing is bent to enclose the edge of the top cap. A crimping portion is formed during the crimping process to secure the top cap to the top of the battery.

[0007] During this crimping process, a large force is applied to the battery housing and the top cap, which causes a large pressure to act toward the center and downward of the top cap, which can cause distortion of the top cap. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above circumstances, and its object is to minimize distortion of the top cap due to crimping pressure during the crimping process.

[0009] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention given below. [Means for solving the problem]

[0010] A cylindrical battery according to one embodiment of the present invention may include: an electrode assembly including a first electrode tab and a second electrode tab; a battery housing that receives the electrode assembly via an opening formed at an upper end; and a top cap configured to cover the opening, the top cap including a folding region including a peripheral region, a central region that is located relatively further inward than the peripheral region, and a first folding portion that is located between the peripheral region and the central region and has a downwardly convex folding shape.

[0011] The central region may be located higher than the peripheral region.

[0012] The upper end of the battery housing may be located higher than the upper end of the central region.

[0013] The lower end of the first folded portion may be located lower than the lower end of the central region and the lower end of the peripheral region.

[0014] The folding region may include a second folding portion having an upwardly convex folded shape.

[0015] The central region may include a second folded portion having an upwardly convex folded shape.

[0016] An upper end of the second folded portion may be positioned at the same height as an upper end of the battery housing.

[0017] The top cap may include a vent configured to be more fragile compared to surrounding areas.

[0018] The vent portion may be further thinned compared to the surrounding area.

[0019] The vent may be provided in the central region.

[0020] The top cap may be configured to be non-polarizable.

[0021] The cylindrical battery may include a first current collector positioned between the electrode assembly and the top cap, the first current collector including a first electrode coupling portion electrically coupled to the first electrode tab and a housing coupling portion coupled onto an inner surface of the battery housing.

[0022] The first bent portion may be located above the housing joint portion.

[0023] A battery pack according to the present invention may include a cylindrical battery according to the present invention.

[0024] A motor vehicle according to the invention may include a battery pack according to the invention. [Effects of the Invention]

[0025] According to one aspect of the present invention, even if a large amount of pressure is applied toward the center of the top cap during the crimping process, the pressure can be buffered through the folded portions. Each time compressive pressure is applied toward the center and bottom of the top cap, only slight distortion occurs at the folded portions due to the already folded portions, while distortion is either not generated or minimized in the generally flat peripheral and central regions. Therefore, distortion of the top cap is minimal during the crimping process, improving the stability and durability of the battery.

[0026] According to another aspect of the present invention, the central region is configured to capture gas generated inside the battery compared to when the central region is positioned lower than the peripheral regions. Therefore, the central region is more susceptible to gas pressure. When an abnormality occurs in the battery and the pressure inside the battery housing increases to a certain level, the central region is ruptured or the crimped portion is released, thereby allowing the gas to escape.

[0027] According to another aspect of the present invention, when the opening is located at the lower end, even if the lower end of the battery housing abuts against the ground or the bottom of the housing for the module or pack, the top cap will not abut against the ground or the bottom of the housing for the module or pack. This reduces the risk of the top cap being scratched or damaged by abrasion. Furthermore, this configuration prevents the pressure required to break the vent formed in the top cap from deviating from the design value.

[0028] According to another aspect of the present invention, the overall height of the top cap can be reduced, and therefore the height of the electrode assembly can be increased by an amount corresponding to the reduced height of the top cap, thereby improving energy density.

[0029] According to yet another aspect of the present invention, the movement of the current collector in the Z-axis direction can be controlled, thereby enabling the current collector to be stably coupled to the battery housing. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a cross-sectional view of a cylindrical battery according to the present invention. [Figure 2] 1 is a diagram showing the appearance of a cylindrical battery according to the present invention. [Figure 3] 1 shows a cylindrical battery according to the present invention before the crimping process. [Figure 4]1 is a partially cut-away view of a top cap included in a cylindrical battery according to the present invention. [Figure 5] 1 is a cross-sectional view of a top cap included in a cylindrical battery according to the present invention. [Figure 6] 1 is a cross-sectional view of a top cap included in a cylindrical battery according to the present invention. [Figure 7] 1 is a cross-sectional view of a top cap included in a cylindrical battery according to the present invention. [Figure 8] 1 is a cross-sectional view of a top cap included in a cylindrical battery according to the present invention. [Figure 9] 1 is a cross-sectional view of a top cap included in a cylindrical battery according to the present invention. [Figure 10] 1 is a cross-sectional view of a top cap included in a cylindrical battery according to the present invention. [Figure 11] 1 is a cross-sectional view of a cylindrical battery according to the present invention. [Figure 12] 1 shows a battery pack according to the present invention; [Figure 13] 1 shows a motor vehicle according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The drawings attached to this specification are intended to illustrate preferred embodiments of the present invention and serve to further understand the technical concepts of the present invention as well as the content of the invention. Therefore, the present invention should not be interpreted as being limited to only the matters depicted in the drawings. The same reference numerals indicate the same components. Note that the thickness, ratio, and dimensions of components in the drawings may be exaggerated for the purpose of effectively explaining the technical content.

[0032] The terms and words used in this 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 corresponding to the technical ideas of the present invention, in accordance with the principle that the inventor can appropriately define the concepts of terms himself / herself in order to best explain the invention.

[0033] On the other hand, although directional terms such as up, down, left, right, front, and rear are used in this specification, it will be obvious to those skilled in the art of the present invention that these terms are used merely for ease of explanation and may differ depending on the position of the object in question, the position of the observer, etc.

[0034] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalent and modified embodiments that can be substituted for them at the time of this application.

[0035] Fig. 1 is a cross-sectional view of a cylindrical battery according to the present invention, Fig. 2 is a view showing the appearance of a cylindrical battery according to the present invention, and Fig. 3 is a view showing a cylindrical battery according to the present invention before a crimping process.

[0036] 1 to 3, a cylindrical battery 10 according to the present invention may include an electrode assembly 100, a battery housing 200, and a top cap 300.

[0037] The electrode assembly 100 may include a first electrode tab 110 and a second electrode tab 120. The electrode assembly 100 includes a first electrode having a first polarity, a second electrode having a second polarity, and a separator sandwiched between the first and second electrodes. The first electrode is a negative or positive electrode, and the second electrode corresponds to an electrode having the opposite polarity to the first electrode. The electrode assembly 100 may be manufactured by winding up a stack formed by stacking the first electrode, separator, second electrode, and separator in this order at least once. In other words, the electrode assembly 100 applicable to the present invention may be a jelly roll-type electrode assembly 100. The first electrode may be a positive or negative electrode, and the second electrode may be an electrode having the opposite polarity to the first electrode.

[0038] Such a jelly roll type electrode assembly 100 may have a central winding hole H1 formed approximately at the center thereof and extending along the height direction (a direction aligned with the Z axis).

[0039] The first electrode may include a first electrode plate and a first electrode active material layer formed by applying a first electrode active material to at least one surface of the first electrode plate. The second electrode may include a second electrode plate and a second active material layer formed by applying a second electrode active material to at least one surface of the second electrode plate. The first electrode may include a first uncoated portion on the electrode plate where no positive or negative electrode active material is applied. The second electrode may include a second uncoated portion on the electrode plate where no positive or negative electrode active material is applied. For example, the first uncoated portion may be provided at the upper end of the electrode assembly 100, and the second uncoated portion may be provided at the lower end of the electrode assembly 100. At least a portion of the first uncoated portion may function as the first electrode tab 110, and at least a portion of the second uncoated portion may function as the second electrode tab 120. Meanwhile, the first electrode tab 110 and the second electrode tab 120 of the present invention are not necessarily limited to being at least a part of the uncoated portion. That is, the first electrode tab 110 and the second electrode tab 120 may be provided separately and coupled to the uncoated portion.

[0040] The battery housing 200 may accommodate the electrode assembly 100 through an opening O formed at its upper end. The battery housing 200 is a generally cylindrical container having an opening O formed at its upper end and may be made of a conductive metal material. The side surfaces of the battery housing 200 and a bottom surface (a surface located in the negative direction of the Z axis) located opposite the opening O may be integrally formed. That is, the battery housing 200 may have an open top end in its height direction and a closed bottom end. The bottom surface of the battery housing 200 may have a generally flat shape. The battery housing 200 may also accommodate an electrolyte through the opening O. However, the battery housing 200 of the present invention is not limited to this shape.

[0041] The battery housing 200 may include a recess 210 and a crimping portion 220 .

[0042] The recess 210 may be formed at an end adjacent to the opening O and may be pressed inward. The recess 210 may have a shape in which the periphery of the battery housing 200 is pressed to a predetermined depth. The recess 210 may be formed at the top of the electrode assembly 100. The inner diameter of the battery housing 200 in the region where the recess 210 is formed may be smaller than the diameter of the electrode assembly 100.

[0043] The crimping portion 220 may be formed on the upper portion of the recess 210. The crimping portion 220 may have an extending and bending shape so as to enclose a peripheral region S1 of the top cap 300, which will be described later. Such a shape of the crimping portion 220 allows the top cap 300 to be fixed on the recess 210.

[0044] Fig. 4 is a partially cutaway view of a top cap included in a cylindrical battery according to the present invention, and Figs. 5 to 10 are cross-sectional views of a top cap included in a cylindrical battery according to the present invention.

[0045] Referring to FIG. 5 in addition to FIGS. 1 to 3, the top cap 300 may be configured to cover the opening O. The top cap 300 may include a peripheral region S1, a central region S3, and a folding region S2. The peripheral region S1 may be located at the outermost side of the top cap 300. The peripheral region S1 may be surrounded by the battery housing 200 during the crimping process. The central region S3 may be located further inward than the peripheral region S1. The folding region S2 may be located between the central region S3 and the peripheral region S1. The folding region S2 may include a first folding portion 320 having a downwardly convex folding shape. However, as shown in FIG. 6, the first folding portion 320 may also have an upwardly convex folding shape.

[0046] The top cap 300 may be configured to have no polarity. That is, the top cap 300 of the present invention may be configured to not be electrically connected to the electrode assembly 100. The top cap 300 may be made of, for example, a metal material to ensure rigidity, but even in such a case, it may have no polarity. The top cap 300 may include an insulating material. However, the present invention is not limited to the top cap 300 having no polarity, and it may have the same polarity as the battery housing 200.

[0047] According to this configuration of the present invention, even if a large pressure is applied toward the center of the top cap 300 during the crimping process described above, the pressure can be buffered via the first folded portion 320. Each time compressive pressure is applied toward the center and bottom of the top cap 300, only slight distortion occurs in the first folded portion 320 due to the first folded portion 320 already being folded, and distortion does not occur or is minimized in the peripheral region S1 and central region S3, which have a generally flat shape. Therefore, distortion of the top cap 300 is minimal even during the crimping process, improving the stability and durability of the battery.

[0048] Referring to FIGS. 4 to 6, the central region S3 may be located higher than the peripheral region S1.

[0049] According to this configuration of the present invention, the central region S3 is configured to collect gas generated inside the battery, compared to when the central region S3 is positioned lower than the peripheral region S1. Therefore, the central region S3 is more susceptible to pressure due to gas. When an abnormality occurs in the battery and the pressure inside the battery housing 200 increases to a certain level, the central region S3 is ruptured or the crimped portion 220 is released, thereby allowing the gas to be discharged.

[0050] 4 to 6 in conjunction with FIG. 1, the upper end of the battery housing 200 may be positioned higher than the upper end of the central region S3.

[0051] According to this configuration of the present invention, when the opening O is located at the lower end, even if the lower end of the battery housing 200 abuts against the ground or the bottom of the housing for the module or pack, the top cap 300 will not abut against the ground or the bottom of the housing for the module or pack. This reduces the risk of the top cap 300 being scratched or damaged by abrasion. Furthermore, even if a vent 310 (described below) is provided in the top cap 300, the vent 310 will not abut against the ground or the bottom of the housing for the module or pack. This prevents the pressure required to break the vent 310 from deviating from the design value due to the weight of the cylindrical battery 10, thereby ensuring uniformity in the breakage of the vent 310.

[0052] 4 and 5, the lower end of the first folded portion 320 may be located lower than the lower end of the central region S3 and the lower end of the peripheral region S1. The lower end of the downwardly folded first folded portion 320 may be located lower than the lower end of the central region S3 and the lower end of the peripheral region S1.

[0053] According to this configuration of the present invention, the overall height of the top cap 300 can be reduced compared to when the first bent portion 320 has an upwardly convex shape or when the lower end of the first bent portion 320 is higher than or equal to the lower ends of the central region S3 and the peripheral region S1. Therefore, the height of the electrode assembly 100 can be increased by an amount corresponding to the reduced height of the top cap 300, thereby improving energy density.

[0054] 7, the folding region S2 may include a second folding portion 330 that is folded to form an upward convex shape. The central region S3 may include a second folding portion 330 that is folded to form an upward convex shape. That is, the second folding portion 330 that is folded to form an upward convex shape may be provided in the folding region S2 and / or the central region S3. However, as shown in FIG. 8, the second folding portion 330 may also have a shape that is folded to form a downward convex shape.

[0055] Furthermore, the folding region S2 and / or the central region S3 may be provided with two or more additional folding portions folded downward or upward.

[0056] 7, the upper end of the second bent portion 330 may be disposed at the same height as the upper end of the battery housing 200. The upper end of the upwardly bent second bent portion 330 may be disposed at the same height as the upper end of the battery housing 200.

[0057] According to this configuration of the present invention, when the opening O is located at the bottom, the battery is supported not only by the battery housing 200 but also by the second bent portion 330, thereby providing more stable support. Furthermore, if a vent portion 310 (described later) is provided in the top cap 300 and is formed further inward from the center than the second bent portion 330, the second bent portion 330 can absorb the crimping pressure, thereby preventing damage caused by force being applied to the vent portion 310 or a phenomenon in which the pressure required to break the vent portion 310 differs from the design value. Furthermore, when two or more bent portions are provided, the crimping pressure that the top cap can absorb increases.

[0058] 1 to 10, the top cap 300 according to the present invention may include a vent portion 310 configured to be more fragile than the surrounding areas. The vent portion 310 may be thinner than the surrounding areas. The vent portion 310 may be provided in a central region S3. The vent portion 310 may be formed by forming notches on either or both sides of the top cap 300 to partially thicken the top cap 300.

[0059] According to this configuration of the present invention, if an abnormality occurs in the battery and the pressure inside the battery housing 200 increases to a certain level, the vent portion 310 is broken, allowing gas to be discharged.

[0060] 1 and 11 , a cylindrical battery 10 according to the present invention may include a first current collector 400. The first current collector 400 may be located between the electrode assembly 100 and the top cap 300. The first current collector 400 may include a first tab coupling portion 410 electrically coupled to the first electrode tab 110. The first current collector 400 may include a housing coupling portion 420 coupled to an inner surface of the battery housing 200.

[0061] The first bent portion 320 may be located on top of the housing coupling portion 420. The first bent portion 320 may be located so as to be placed in contact with the housing coupling portion 420. However, even if they are not in contact or connected, the first bent portion 320 may be located so as to overlap the housing coupling portion 420 along the extension direction of the Z axis. When the top cap is configured not to have polarity, at least the first bent portion 320 connected to the housing coupling portion 420 may be insulated.

[0062] According to this configuration of the present invention, when the housing coupling part 420 moves due to gas generation inside the battery or due to an external impact, the upward movement (in the positive direction of the Z axis) can be controlled by the first bent part 320. Therefore, the housing coupling part 420 can be stably coupled to the battery housing 200.

[0063] 1 and 11, a cylindrical battery 10 according to the present invention may include a terminal T, a second current collector P, and an insulator I.

[0064] The terminal T may be electrically connected to the second electrode tab 120. The terminal T may be electrically connected to the second electrode tab 120 by passing through a closed portion of the battery housing 200 provided on the opposite side of the open portion O of the battery housing 200. The terminal T may pass through approximately the center of the lower surface of the battery housing 200. The terminal T may be electrically connected to the electrode assembly 100 by being coupled to a second current collector P described below.

[0065] The second current collector P may be electrically coupled to the second electrode tab 120. The second current collector P may be electrically coupled to the terminal T. The second current collector P may include a terminal coupling portion coupled to the terminal T and a second tab coupling portion coupled to the second electrode tab 120.

[0066] The insulator I may be positioned on the second electrode tab 120 to insulate the battery housing 200 from the second electrode tab 120. The insulator I may be interposed between the closing portion of the battery housing 200 and the electrode assembly 100 or between the closing portion of the battery housing 200 and the second current collector P. The insulator I may include, for example, a resin material having insulating properties. The insulator I may have a hole approximately in the center so that the terminal T can be electrically connected to the second electrode tab 120.

[0067] FIG. 12 shows a battery pack 2 according to the present invention.

[0068] 12 , a battery pack 2 according to the present invention may include a cylindrical battery 10. In addition to the cylindrical battery 10, the battery pack 2 may further include various other components, such as a battery management system (BMS), bus bars, a pack case, a relay, a current sensor, and other components of a battery pack 2 that are known at the time of filing of the present invention.

[0069] When the cylindrical battery 10 included in the battery pack 2 shown in Fig. 12 is placed with the top cap 300 facing downward, the battery housing 200 functioning as the first electrode terminal and the terminal T functioning as the second electrode terminal are located at the top. This facilitates electrical connection at the top. Furthermore, as described above, the vent portion 310 does not abut against the ground or the bottom surface of the housing that constitutes the module or pack, which prevents the pressure required to break the vent portion 310 from differing from the design value due to the weight of the cylindrical battery 10. This ensures uniformity in the breakage of the vent portion 310.

[0070] FIG. 13 shows a vehicle 1 according to the invention.

[0071] 13, an automobile 1 according to the present invention may include a battery pack 2. The automobile 1 may be a hybrid automobile 1 or an electric automobile 1. In addition to the battery pack 2, the automobile 1 according to the present invention may further include various other components included in the automobile 1. For example, in addition to the battery pack 2 according to the present invention, the automobile 1 according to the present invention may further include a vehicle body, a motor, a control device such as an electronic control unit (ECU), and the like.

[0072] While the present invention has been described above with emphasis on preferred embodiments and with reference to the accompanying drawings, it will be apparent to those skilled in the art that various and obvious modifications may be made thereto without departing from the scope of the present invention, and the scope of the present invention should therefore be determined by the claims which are written to include all such various modified embodiments. [Explanation of symbols]

[0073] 1. Electric vehicles (hybrid vehicles) 2 battery packs 10 Cylindrical battery 100 electrode assembly 110 first electrode tab 120 Second electrode tab 200 Battery Housing 210 Depression 220 Crimping section 300 top cap 310 Vent 320 Bending section 330 Bending section 400 First current collector 410 first tab joint 420 At least the housing joint 420 Housing joint H1 center hole I Insulator O open part P Second current collector S1 Edge Region S2 Region S3 Central Region T Terminal

Claims

1. an electrode assembly including a first electrode tab and a second electrode tab; a battery housing that accommodates the electrode assembly through an opening formed at an upper end thereof; a top cap configured to cover the opening, the top cap including: a peripheral region; a central region located relatively further inward than the peripheral region; and a folding region located between the peripheral region and the central region, the folding region including a first folding portion having a shape folded so as to be convex downward; Cylindrical battery, including

2. 2. The cylindrical battery of claim 1, wherein the central region is located higher than the peripheral regions.

3. The cylindrical battery according to claim 2 , wherein an upper end of the battery housing is positioned higher than an upper end of the central region.

4. The cylindrical battery according to claim 1 , wherein a lower end of the first folded portion is located lower than a lower end of the central region and a lower end of the peripheral region.

5. The folding region is The cylindrical battery according to claim 1 , further comprising a second folded portion having an upwardly convex folded shape.

6. The central region is The cylindrical battery according to claim 1 , further comprising a second folded portion having an upwardly convex folded shape.

7. The cylindrical battery according to claim 5 , wherein an upper end of the second folded portion is positioned at the same height as an upper end of the battery housing.

8. The top cap is 10. The cylindrical battery of claim 1, comprising a vent configured to be more fragile compared to surrounding areas.

9. The vent portion is 9. The cylindrical battery of claim 8, further thinned compared to the surrounding area.

10. The vent portion is The cylindrical battery according to claim 8 , wherein the insulating layer is provided in the central region.

11. 9. The cylindrical battery according to claim 8, wherein the top cap is configured to have no polarity.

12. The cylindrical battery is a first electrode coupling portion electrically coupled to the first electrode tab; a housing coupling portion coupled to an inner surface of the battery housing; Equipped with 10. The cylindrical battery according to claim 1, further comprising a first current collector located between the electrode assembly and the top cap.

13. The cylindrical battery according to claim 12 , wherein the first bent portion is located above the housing joint portion.

14. A battery pack comprising the cylindrical battery according to any one of claims 1 to 13.

15. A motor vehicle comprising the battery pack of claim 14.

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