Secondary battery, battery pack, and automobile

Abstract

The present invention provides a secondary battery comprising: an electrode assembly having a first electrode tab and a second electrode tab; a battery can having an opening for accommodating the electrode assembly and electrically connected to the second electrode tab; a top cap covering the opening of the battery can and electrically connected to the first electrode tab; a conductive washer electrically connected to the battery can and in contact with at least a portion of a periphery of the opening; and an insulating member disposed between the battery can, the conductive washer electrically connected to the battery can, and the top cap, electrically insulating the top cap from at least one of the battery can and the conductive washer, wherein the top cap has first and second surfaces facing each other, the first surface facing the electrode assembly and electrically connected to the first electrode tab, and the second surface having a protrusion exposed through a hole formed in the center of the conductive washer.

Description

[Technical field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2021-0024422 filed with the Korean Intellectual Property Office on February 23, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a secondary battery, a battery pack, and an automobile. [Background technology]

[0003] Secondary batteries, which have high ease of application depending on the product group 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 electric drive sources.

[0004] Such secondary batteries have the primary advantage of dramatically reducing the use of fossil fuels, as well as the advantage of not producing any by-products from the use of energy, and are therefore drawing attention as a new energy source that is environmentally friendly and improves energy efficiency.

[0005] Currently, the types of secondary batteries that are widely used include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel hydrogen batteries, and nickel zinc batteries. The operating voltage of such unit secondary batteries, i.e., unit batteries, is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a battery pack may be configured by connecting a plurality of secondary batteries in series. Also, a battery pack may be configured by connecting a plurality of secondary batteries in parallel depending on the charge / discharge capacity required for the battery pack. Therefore, the number and electrical connection form of the secondary batteries included in the battery pack may be variously set depending on the required output voltage and / or charge / discharge capacity.

[0006] When preparing a battery pack using cylindrical secondary batteries, typically, multiple cylindrical secondary batteries are arranged upright in a housing, and the upper and lower ends of the cylindrical secondary batteries are used as positive and negative terminals, respectively, to electrically connect the multiple cylindrical secondary batteries to each other.

[0007] This is because, in a cylindrical secondary battery, the negative electrode uncoated portion of the electrode assembly housed inside the battery can extends downward to be electrically connected to the bottom surface of the battery can, and the positive electrode uncoated portion extends upward to be electrically connected to the top cap. That is, in a cylindrical secondary battery, the bottom surface of the battery can is generally used as the negative electrode terminal, and the top cap that covers the top opening of the battery can is generally used as the positive electrode terminal.

[0008] However, when the positive and negative terminals of the cylindrical secondary batteries are located on opposite sides of each other, electrical connection components such as bus bars for electrically connecting a plurality of cylindrical secondary batteries must be provided on both the upper and lower parts of the cylindrical secondary batteries, which complicates the electrical connection structure of the battery pack.

[0009] Furthermore, in such a structure, components for insulation and components for ensuring waterproofing must be applied separately to the upper and lower parts of the battery pack, resulting in an increase in the number of components applied and a complicated structure.

[0010] Therefore, there is a need to develop a cylindrical secondary battery having a structure in which positive and negative terminals are applied in the same direction so that the electrical connection structure of a plurality of cylindrical secondary batteries can be simplified. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention aims to provide a secondary battery capable of achieving high energy density by having a structure in which a positive electrode terminal and a negative electrode terminal are applied in the same direction and a top cap that serves as a positive electrode terminal and a part that enables welding of a tab extending from an electrode assembly are combined into one.

[0012] Another object of the present invention is to provide a battery pack and an automobile including the above-mentioned secondary battery.

[0013] However, the technical problems that the present invention aims to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0014] One embodiment of the present invention provides a secondary battery comprising: an electrode assembly having a first electrode tab and a second electrode tab; a battery can having an opening for accommodating the electrode assembly and electrically connected to the second electrode tab; a top cap covering the opening of the battery can and electrically connected to the first electrode tab; a conductive washer electrically connected to the battery can and in contact with at least a portion of a periphery of the opening; and an insulating member provided between the top cap and at least one of the battery can and the conductive washer electrically connected to the battery can, and electrically insulating the top cap from at least one of the battery can and the conductive washer, the top cap comprising first and second surfaces opposed to each other, the first surface facing the electrode assembly and electrically connected to the first electrode tab, and the second surface having a protrusion exposed through a hole formed in the center of the conductive washer.

[0015] Another embodiment of the present invention provides a battery pack including the secondary battery according to the above embodiment; and a pack housing that houses the secondary battery.

[0016] Another embodiment of the present invention provides a vehicle including a battery pack according to the above-described embodiment. Effect of the Invention

[0017] In the case where a conductive washer is applied to a cylindrical secondary battery having a structure in which a positive electrode terminal and a negative electrode terminal are applied in the same direction, a top cap functioning as a positive electrode terminal may be applied in a form including a protrusion formed to protrude toward the outside of a battery can so that the conductive washer has a sufficiently wide width. The top cap including such a protrusion may be manufactured by pressing, and a connection plate, which is an intermediate part for electrical connection with the electrode assembly, may be attached to the lower part of the top cap.

[0018] According to one aspect of the present invention, a tab extending from an electrode assembly can be directly welded to a top cap including a protrusion without attaching a separate connection plate to the top cap that functions as a positive terminal. In this case, the number of parts for electrical connection can be reduced, and the resistance of the parts can be reduced. In addition, when this configuration is applied, the rigidity of the top cap can be increased due to the top cap parts manufactured by forging.

[0019] According to another aspect of the present invention, the energy density of the secondary battery can be increased by ensuring low electrical resistance at the positive terminal due to the reduced resistance at the top cap, which allows the battery size to be increased. [Brief description of the drawings]

[0020] The following drawings attached to this specification are intended to illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical ideas of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters described in the drawings.

[0021] [Figure 1]FIG. 13 is a diagram showing a cylindrical secondary battery structure in which a top cap as a positive electrode terminal and a conductive washer as a negative electrode terminal are applied according to a comparative example of the present invention, in which a separate connecting plate part is applied to a lower part of the top cap for connecting with a tab drawn out from an electrode assembly. [Diagram 2] 1 is a diagram showing the appearance of a cylindrical secondary battery according to an embodiment of the present invention; [Diagram 3] 1 is a cross-sectional view showing an internal structure of a cylindrical secondary battery according to an embodiment of the present invention. [Figure 4] 2 is a diagram showing a cylindrical secondary battery structure according to an embodiment of the present invention, in which a connecting plate part is omitted by applying a positive forged top cap to the secondary battery shown in FIG. 1. FIG. [Diagram 5] 2 is a partial cross-sectional view showing an upper structure of a cylindrical secondary battery according to an embodiment of the present invention; [Figure 6] 2 is a partial cross-sectional view showing an upper structure of a cylindrical secondary battery according to an embodiment of the present invention; [Figure 7] 2 is a partial cross-sectional view showing an upper structure of a cylindrical secondary battery according to an embodiment of the present invention; [Figure 8] 2 is a partial cross-sectional view showing an upper structure of a cylindrical secondary battery according to an embodiment of the present invention; [Figure 9] FIG. 2 is a diagram showing a current collecting plate applied to the present invention. [Figure 10] FIG. 2 is a diagram showing a current collecting plate applied to the present invention. [Figure 11] 4 is a cross-sectional view showing a coupling structure between a current collecting plate and an electrode assembly according to the present invention; [Figure 12] 4 is a cross-sectional view showing a coupling structure between a current collecting plate and an electrode assembly according to the present invention; [Figure 13] 2 is a partial cross-sectional view showing a lower structure of a cylindrical secondary battery according to an embodiment of the present invention; [Figure 14] 2 is a diagram showing the bottom surface of a cylindrical secondary battery according to an embodiment of the present invention; FIG. [Figure 15] 1 is a schematic diagram illustrating a battery pack according to one embodiment of the present invention. [Figure 16] 1 is a conceptual diagram illustrating a vehicle according to an embodiment of the present invention. [Explanation of symbols]

[0022] 5. Automotive 3 Battery pack 2-Pack Housing 1. Cylindrical secondary battery 10...electrode assembly 11 First electrode tab 12 Second electrode tab 20 Battery can 21 Beading section 22 Crimping section 22a Insertion groove 23 Vent section 30 ···Top Cap 31...Protrusion 32...Non-protruding part 33...1st surface (flat part) 34...Second side (exposed part) 40 Conductive washer 41 Insertion protrusion 55 Insulating member 50 Second insulating member 60 First insulating member 70 ···Current collecting plate 71 Subplate 72 Lead 80 Insulation plate 81 Lead Hall 90 ···Connecting plate DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to that, 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 being consistent with the technical ideas of the present invention, in accordance with the principle that the inventors can appropriately define the concepts of terms in order to best describe their invention. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely some of the most preferred embodiments of the present invention, and do not represent the entire technical ideas of the present invention, and therefore there may be various equivalents and modifications that can replace them at the time of filing this application.

[0024] Throughout the specification, when a part "includes" a certain component, this does not mean excluding other components, but means that the part may further include other components, unless otherwise specified. Furthermore, "part" described in the specification means a unit that processes at least one function or operation. Furthermore, throughout the specification, "A to B" means A or more and B or less, and means a numerical range including both A and B. Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0025] One embodiment of the present invention provides a secondary battery comprising: an electrode assembly having a first electrode tab and a second electrode tab; a battery can having an opening for accommodating the electrode assembly and electrically connected to the second electrode tab; a top cap covering the opening of the battery can and electrically connected to the first electrode tab; a conductive washer electrically connected to the battery can and in contact with at least a portion of a periphery of the opening; and an insulating member provided between the battery can and the conductive washer electrically connected to the battery can and the top cap, electrically insulating at least one of the battery can and the conductive washer from the top cap, wherein the top cap has first and second surfaces facing each other, the first surface facing the electrode assembly and electrically connected to the first electrode tab, and the second surface having a protrusion exposed through a hole formed in the center of the conductive washer.

[0026] The secondary battery includes the conductive washer, and thus a unidirectional electrical connection can be realized in which the positive and negative terminals are applied in the same direction. In this case, a tab extending from the electrode assembly can be directly welded to the top cap, which functions as the positive terminal, without attaching a separate connection plate to the top cap. Thus, a top cap with reduced component resistance and increased energy density of the secondary battery can be manufactured.

[0027] Furthermore, when the above-described configuration is applied, the rigidity of the top cap can be increased by the top cap part manufactured by forging.

[0028] The secondary battery may be a cylindrical secondary battery, and the first electrode tab may be an uncoated portion of a first electrode collector constituting the electrode assembly where a first electrode active material is not formed, and the second electrode tab may be an uncoated portion of a second electrode collector constituting the electrode assembly where a second electrode active material is not formed.

[0029] The first electrode tab and the second electrode tab may be bent toward a winding center of the electrode assembly.

[0030] The electrode tabs are folded, which is advantageous in ensuring low electrical resistance and can increase the energy density of the secondary battery.

[0031] 2 to 7, a cylindrical secondary battery 1 according to an embodiment of the present invention includes an electrode assembly 10, a battery can 20, a top cap 30, a conductive washer 40, and an insulating member 55. The top cap 30 includes a first surface 33 and a second surface 34 facing each other. The first surface 33 faces the electrode assembly and is electrically connected to the first electrode tab 11. The second surface 34 is provided on a protrusion exposed through a hole formed in the center of the conductive washer 40.

[0032] The cylindrical secondary battery 1 may further include a current collecting plate 70 and / or an insulating plate 80 in addition to the above-mentioned components.

[0033] 2 to 7, the electrode assembly 10 includes a first electrode plate having a first polarity, a second electrode plate having a second polarity, and a separator provided between the first and second electrode plates. The electrode assembly 10 may have a jelly-roll shape. That is, the electrode assembly 10 may be manufactured by sequentially stacking the first electrode plate, the separator, and the second electrode plate at least once, and winding the stacked body around a winding center C. In this case, a separator may be provided on the outer circumferential surface of the electrode assembly 10 for insulation from the battery can 20. The first electrode plate is a positive electrode plate or a negative electrode plate, and the second electrode plate is an electrode plate having a polarity opposite to that of the first electrode plate. For example, the first electrode plate may be a positive electrode plate, and the second electrode plate may be a negative electrode plate.

[0034] The first electrode plate includes a first electrode collector and a first electrode active material applied on one or both sides of the first electrode collector. An uncoated portion where the first electrode active material is not applied exists at one end of the first electrode collector in the width direction (direction parallel to the Z axis). The uncoated portion functions as a first electrode tab 11. The first electrode tab 11 is provided at the upper part of the electrode assembly 10 housed in the battery can 20 in the height direction (direction parallel to the Z axis).

[0035] The second electrode plate includes a second electrode collector and a second electrode active material applied on one or both sides of the second electrode collector. An uncoated portion where the second electrode active material is not applied exists at the other end of the second electrode collector in the width direction (direction parallel to the Z axis). The uncoated portion functions as a second electrode tab 12. The second electrode tab 12 is provided at the lower part of the electrode assembly 10 housed in the battery can 20 in the height direction (direction parallel to the Z axis).

[0036] That is, a first electrode tab 11 may be provided at one end of the electrode assembly, and a second electrode tab may be provided at the other end.

[0037] 2 to 7, the battery can 20 may be cylindrical, and is a cylindrical container having an opening and made of a conductive metal material. The battery can 20 accommodates the electrode assembly 10 through the opening, and also accommodates an electrolyte.

[0038] The battery can 20 is electrically connected to the second electrode tab 12 of the electrode assembly 10. Therefore, the battery can 20 has the same polarity as the second electrode tab 12. For example, the second electrode tab 12 may be attached to the battery can 20 by welding.

[0039] The battery can 20 includes a beading portion 21 and a crimping portion 22 formed on an upper end thereof. The crimping portion 22 may be provided on the periphery of the opening of the battery can 20.

[0040] The beading portion 21 is formed on the upper portion of the electrode assembly 10. The beading portion 21 is formed by pressing the outer periphery of the battery can 20. The beading portion 21 prevents the electrode assembly 10, which has a size corresponding to the width of the battery can 20, from slipping out through the upper opening of the battery can 20, and can function as a support on which a top cap 30 is placed.

[0041] The crimping portion 22 is formed on the upper portion of the beading portion 21. The crimping portion 22 has an extended and bent shape so as to surround the outer circumferential surface of the top cap 30 disposed on the beading portion 21 and a part of the upper surface of the top cap 30.

[0042] The battery can may be cylindrical, and its size may be a circular diameter at both ends of 30 mm to 55 mm, and a height of 60 mm to 120 mm. For example, the circular diameter x height of the cylindrical battery can may be 46 mm x 60 mm, 46 mm x 80 mm, 46 mm x 90 mm, or 46 mm x 120 mm.

[0043] Preferably, the cylindrical secondary battery may be, for example, a cylindrical secondary battery having a form factor ratio (defined as the diameter of the cylindrical secondary battery divided by the height, i.e., the ratio of the height (H) to the diameter (Φ)) of greater than about 0.4.

[0044] Here, the form factor means a value indicating the diameter and height of a cylindrical secondary battery. The cylindrical secondary battery according to an embodiment of the present invention may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, a 46800 cell, and a 46900 cell. In the numerical value indicating the form factor, the first two digits indicate the diameter of the cell, the next two digits indicate the height of the cell, and the final digit 0 indicates that the cross section of the cell is circular.

[0045] A cylindrical secondary battery according to one embodiment of the present invention may be a cylindrical secondary battery having a substantially cylindrical cell shape, a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of about 0.418.

[0046] A cylindrical secondary battery according to another embodiment may be a battery cell having a substantially cylindrical shape, a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of about 0.640.

[0047] A cylindrical secondary battery according to another embodiment may be a cylindrical secondary battery having a substantially cylindrical cell with a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of about 0.418.

[0048] A cylindrical secondary battery according to yet another embodiment may be a battery cell having a substantially cylindrical shape, a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of about 0.600.

[0049] A cylindrical secondary battery according to yet another embodiment may be a battery cell having a substantially cylindrical shape, a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of about 0.575.

[0050] A cylindrical secondary battery according to still another embodiment may be a cylindrical secondary battery having a substantially cylindrical cell with a diameter of about 46 mm, a height of about 90 mm, and a form factor ratio of 0.511.

[0051] 13 and 14, the battery can 20 may further include a vent portion 23 formed on the bottom surface thereof. The vent portion 23 corresponds to a region in the bottom surface of the battery can 20 that is thinner than the surrounding region. The vent portion 23 is structurally weaker than the surrounding region. Therefore, when an abnormality occurs in the cylindrical secondary battery 1 and the internal pressure increases above a certain level, the vent portion 23 breaks, and gas generated inside the battery can 20 is discharged.

[0052] As described below, the cylindrical secondary battery 1 according to an embodiment of the present invention has a structure in which both the positive and negative terminals are present at the upper portion, and therefore the structure of the upper portion is more complicated than that of the lower portion. Therefore, in order to smoothly exhaust gas generated inside the battery can 20, a vent portion 23 may be included at the lower surface of the battery can 20.

[0053] Although the drawings of the present invention show only a case where the vent portion 23 is continuously formed in a circle on the lower surface of the battery can 20, the present invention is not limited thereto. The vent portion 23 may be discontinuously formed in a circle on the lower surface of the battery can 20, or may be formed in a straight line or in other shapes.

[0054] 2 to 7, the top cap 30 is a part made of a conductive metal material and covers the opening of the battery can 20. The top cap 30 is electrically connected to the first electrode tab 11 of the electrode assembly 10 and is electrically insulated from the battery can 20. Therefore, the top cap 30 can function as a first electrode terminal of the cylindrical secondary battery 1.

[0055] The top cap 30 is placed on a beading portion 21 formed on the battery can 20 and fixed by a crimping portion 22 .

[0056] The top cap 30 includes a first surface 33 and a second surface 34 facing each other, the first surface 33 facing the electrode assembly and electrically connected to the first electrode tab 11, and the second surface 34 included in a protrusion 31 exposed through a hole formed in the center of the conductive washer 40.

[0057] The first surface 33 faces the inside of the battery can, and the second surface 34 faces the outside of the battery can. That is, the top cap 30 may have a protrusion 31 formed to protrude toward the outside of the battery can, and the second surface 34 may be an exposed portion exposed through a hole formed in the center of the conductive washer 40 in the protrusion 31.

[0058] The protrusion 31 can protrude higher than the upper surface of a conductive washer 40 described below so as to facilitate contact with an electrical connection part such as a bus bar. The upper surface refers to the outer side of the battery can of the cylindrical battery, i.e., the side where the opening is located, and the lower surface refers to the side where the bottom surface of the battery can is located.

[0059] The first surface 33 of the top cap 30 may be a flat portion electrically connected to the first electrode tab 11, and the second surface 34 of the top cap 30 may be an exposed portion exposed through the outer surface of the conductive washer 40 at the protrusion 31.

[0060] Therefore, the first electrode tab 11 can be electrically connected without attaching a separate connection plate component to the first surface 33 of the top cap 30. As an example, the first electrode tab 11 can be welded to the first surface 33 of the top cap 30. In this case, the number of components for electrical connection can be reduced, and therefore the resistance of the components can be reduced.

[0061] In addition, the top cap 30 can function as a first electrode terminal of the cylindrical secondary battery 1 due to the second surface 34 having an exposed portion exposed through the outer surface of the conductive washer 40 electrically connected to the electrode assembly. That is, the second surface of the protrusion 31 is exposed through a hole formed in the center of the conductive washer, which can function as a first electrode terminal.

[0062] The top cap 30 includes a non-protruding portion 32 that is not provided with the protruding portion 31, and the height of the protruding portion from the first surface 33 is formed to be higher than the height of the non-protruding portion 32 from the first surface 33.

[0063] The height ratio of the protruding portion 31 and the non-protruding portion 32 from the first surface 33 can be set by surrounding components. The protruding portion 31 can protrude higher than the upper surface of a conductive washer 40 described later so as to facilitate contact with an electrical connection component such as a bus bar. The upper surface refers to the outer direction of the battery can of the cylindrical battery, i.e., the direction in which the opening is located, and the lower surface refers to the direction in which the bottom surface of the battery can is located.

[0064] That is, the height of the protruding portion from the first surface 33 may be greater than the combined height of the non-protruding portion 32 from the first surface 33, the thickness T1 of the crimping portion 22 described below, and the thickness T2 of the conductive washer 40 in contact with the crimping portion 22 (see Figure 6).

[0065] The thickness T1 of the crimping portion 22 may be 0.1 mm or more, 0.15 mm or more, 0.2 mm or more, 0.25 mm or more, 0.3 mm or more, or 0.35 mm or more. The thickness T1 of the crimping portion 22 may be 0.75 mm or less, 0.7 mm or less, 0.65 mm or less, 0.6 mm or less, 0.55 mm or less, or 0.5 mm or less.

[0066] The thickness T2 of the conductive washer 40 in contact with the crimping portion 22 may be 0.25 mm or more, 0.3 mm or more, 0.35 mm or more, or 0.4 mm or more. The thickness T2 of the conductive washer 40 in contact with the crimping portion 22 may be 0.65 mm or less, 0.6 mm or less, 0.55 mm or less, or 0.5 mm or less.

[0067] The combined thickness T1 of the crimping portion 22 and the thickness T2 of the conductive washer 40 in contact with the crimping portion 22 may be 0.35 mm or more, 0.4 mm or more, 0.45 mm or more, 0.5 mm or more, 0.55 mm or more, 0.6 mm or more, or 0.65 mm or more. The combined thickness T1 of the crimping portion 22 and the thickness T2 of the conductive washer 40 in contact with the crimping portion 22 may be 1.4 mm or less, 1.35 mm or less, 1.3 mm or less, 1.25 mm or less, 1.2 mm or less, 1.15 mm or less, 1.1 mm or less, 1.05 mm or less, or 1 mm or less.

[0068] Therefore, the height of the protruding portion from the first surface 33 may be greater than the sum of the height of the non-protruding portion 32 from the first surface 33 and 0.35 mm or more, 0.4 mm or more, 0.45 mm or more, 0.5 mm or more, 0.55 mm or more, 0.6 mm or more, or 0.65 mm or more, or 1.4 mm or less, 1.35 mm or less, 1.3 mm or less, 1.25 mm or less, 1.2 mm or less, 1.15 mm or less, 1.1 mm or less, 1.05 mm or less, or 1 mm or less.

[0069] Due to the height ratio of the protruding portion 31 and the non-protruding portion 32 from the first surface 33, the protruding portion 31 can expose the second surface through a hole formed in the center of the conductive washer, which is advantageous for functioning as a first electrode terminal.

[0070] FIG. 1 is a diagram showing a cylindrical secondary battery structure in which a top cap as a positive terminal and a conductive washer as a negative terminal are applied according to a comparative example of the present invention, in which a separate connecting plate part is applied to a lower part of the top cap for connecting with a tab drawn out from an electrode assembly.

[0071] Referring to FIG. 1, in a cylindrical secondary battery structure in which a conductive washer 40 is applied for a wide negative terminal, in order to obtain a desired conductive washer area, a positive electrode top cap 30 is pressed so that a protruding portion 31 of the positive electrode top cap can be inserted into a central hole of the conductive washer 40, and a connection plate 90 component is attached to its lower surface to form a current path with the electrode assembly.

[0072] However, in order to reduce the number of parts and reduce resistance compared to applying the connecting plate 90 part in this manner, a positive forged top cap can be applied.

[0073] FIG. 4 is a diagram showing a cylindrical secondary battery structure according to an embodiment of the present invention, in which a connecting plate part is omitted by applying a positive forged top cap to the secondary battery shown in FIG.

[0074] That is, referring to Fig. 4, a structure is presented in which a part that acts as an external terminal of the positive electrode and a part to which a tab drawn from an electrode assembly can be welded are combined into one. The positive electrode forged top cap made of one part is manufactured by forging, so its rigidity can be increased compared to existing top caps, and the integrated application into one part also reduces the resistance of the part.

[0075] The forged top cap 30 means a top cap made by a forging method, and the forging method means applying pressure to the non-protruding portion 32 in the direction from the second surface 34 to the first surface 33 on the upper surface of the top cap 30 to form the protruding portion 31.

[0076] The top cap 30 includes aluminum, which increases its rigidity compared to existing top caps and ensures a space where tabs extending from the electrode assembly can be welded.

[0077] In this manner, the application of the positive electrode forged top cap part of the present invention allows one part to perform two functions, i.e., the function as a positive electrode external terminal and the function as a part for attaching an internal tab, and the forging method allows the part to have higher rigidity than existing top cap parts and to exhibit lower part resistance than when the two parts are applied separately.

[0078] 2 to 8, the conductive washer 40 is made of a conductive metal material and is a substantially disk-shaped part having a hole formed in the center thereof.

[0079] The conductive washer 40 extends from the outer periphery of the upper surface of the conductive washer 40 that contacts the peripheral edge of the opening of the battery can toward the center, and a hole is formed in the center so that the protrusion 31 of the top cap 30 can be exposed.

[0080] The upper surface means the outer side of the cylindrical battery can, i.e., the side where the opening is located, and the lower surface means the side where the bottom surface of the battery can is located. The central portion means the central region of the upper surface and / or the lower surface of the conductive washer 40.

[0081] The conductive washer 40 is electrically connected to the battery can and can be in contact with at least a portion of the periphery of the opening, preferably on the crimping portion 22 of the battery can 20. That is, the secondary battery has a crimping portion on the periphery of the opening of the battery can, and the conductive washer 40 is in contact with the crimping portion 22. By being in contact with the crimping portion 22, the conductive washer 40 can have the same polarity as the battery can and can function as a second electrode terminal having a second polarity.

[0082] The conductive washer 40 can be bonded onto the crimping portion 22, the bonding may be done, for example, by welding, the welding may be laser welding.

[0083] The conductive washer 40 is electrically insulated from the top cap 30. The top cap 30 is exposed through a hole formed in the center of the conductive washer 40, and the conductive washer 40 and the protruding portion 31 of the top cap 30 are spaced apart from each other. In addition, the conductive washer 40 is vertically spaced apart from the remaining portion of the top cap 30 excluding the protruding portion 31. Therefore, the conductive washer 40 is electrically connected to the second electrode tab 12 and the battery can 20, and can function as a second electrode terminal of the cylindrical secondary battery 1.

[0084] In other words, the cylindrical secondary battery 1 according to one embodiment of the present invention has a structure in which the first electrode terminal having a first polarity and the second electrode terminal having a second polarity are all arranged in the same direction by including the conductive washer 40.

[0085] Referring to FIG. 5, the width D2 of the conductive washer 40 is greater than the width D1 of the upper surface of the crimping portion 22 of the battery can 20.

[0086] This is to increase the bonding area between the electrical connecting part, such as a bus bar, and the conductive washer 40 when the electrical connecting part is coupled to the conductive washer 40 in order to connect a plurality of cylindrical secondary batteries 1. By increasing the bonding area between the electrical connecting part and the conductive washer 40 in this manner, the welding process can be performed smoothly, the fastening force between the two parts can be improved, and the electrical resistance at the bonding site can be reduced.

[0087] The upper surface means the outer direction of the battery can of the cylindrical battery, i.e., the direction where the opening is located, and the lower surface means the direction where the bottom surface of the battery can is located. The width D2 of the conductive washer 40 means the length extending from the outer periphery of the upper surface of the conductive washer 40 that contacts the periphery of the opening of the battery can toward the center. The width D1 of the upper surface of the crimping portion 22 means the length extending from the periphery of the opening of the battery can toward the center from the outer periphery of the upper surface of the battery can. The upper surface of the crimping portion 22 means the portion excluding the bent portion surrounding the side and edge portions of the crimping portion 22 from the end of the crimping portion 22.

[0088] The width D2 of the conductive washer 40 can be set differently depending on the diameter of the secondary battery. The cylindrical secondary battery may be a substantially cylindrical cell, and the width D2 of the conductive washer 40 may be, for example, 10% or more, 11% or more, 12% or more, or 13% or more of the maximum diameter of the cell. The cylindrical secondary battery may be a substantially cylindrical cell, and the width D2 of the conductive washer 40 may be, for example, 50% or less, 45% or less, 43% or less, or 40% or less of the maximum diameter of the cell.

[0089] The width D1 of the upper surface of the crimping portion 22 is smaller than the width D2 of the conductive washer 40. The cylindrical secondary battery is a substantially cylindrical cell, and the width D1 of the upper surface of the crimping portion 22 may be, for example, 1% or more, 2% or more, or 3% or more of the maximum diameter of the cell. The cylindrical secondary battery is a substantially cylindrical cell, and the width D1 of the upper surface of the crimping portion 22 may be, for example, 13% or less, 12% or less, 11% or less, or 10% or less of the maximum diameter of the cell.

[0090] Referring to FIG. 6, the sum of the thickness T1 of the crimping portion 22 at the portion in contact with the conductive washer 40 and the thickness T2 of the conductive washer 40 in contact with the crimping portion 22 is 90% to 200% of the thickness T' of the conductive washer 40 not in contact with the crimping portion 22.

[0091] For example, the thickness T1 of the crimping portion 22 may be 0.1 mm or more, 0.15 mm or more, 0.2 mm or more, 0.25 mm or more, 0.3 mm or more, or 0.35 mm or more. The thickness T1 of the crimping portion 22 may be 0.75 mm or less, 0.7 mm or less, 0.65 mm or less, 0.6 mm or less, 0.55 mm or less, or 0.5 mm or less.

[0092] The thickness T2 of the conductive washer 40 in contact with the crimping portion 22 may be 0.25 mm or more, 0.3 mm or more, 0.35 mm or more, or 0.4 mm or more. The thickness T2 of the conductive washer 40 in contact with the crimping portion 22 may be 0.65 mm or less, 0.6 mm or less, 0.55 mm or less, or 0.5 mm or less.

[0093] The thickness T' of the conductive washer 40 not in contact with the crimping portion 22 may be 0.4 mm or more, 0.45 mm or more, or 0.5 mm or more. The thickness T' of the conductive washer 40 not in contact with the crimping portion 22 may be 0.7 mm or less, 0.65 mm or less, or 0.6 mm or less.

[0094] When the conductive washer is formed to have different thicknesses in different regions, the metal thickness on all current paths is the same, thereby reducing the overall resistance.

[0095] Meanwhile, referring to FIG. 8, the battery can 20 may include an insertion groove 22a provided on an upper surface of the crimping portion 22, and the conductive washer 40 may include an insertion protrusion 41 having a shape corresponding to the insertion groove 22a and coupled to the insertion groove 22a.

[0096] The insertion groove 22a and the insertion protrusion 41 can increase the contact area between the conductive washer 40 and the crimping portion 22, improving the fastening force and reducing the electrical resistance at the joining portion. Furthermore, the insertion groove 22a and the insertion protrusion 41 can prevent the conductive washer 40 from contacting the protrusion 31 of the top cap 30 by guiding the placement position when the conductive washer 40 is placed on the crimping portion 22. Furthermore, the insertion groove 22a and the insertion protrusion 41 can improve the processability by preventing the conductive washer 40 from moving on the crimping portion 22 during the welding process.

[0097] 2 to 7, the insulating member 55 is provided between the top cap 30 and at least one of the battery can 20 and the conductive washer 40 electrically connected to the battery can, and electrically insulates the top cap 30 from at least one of the battery can 20 and the conductive washer 40. According to one example, the insulating member 55 may electrically insulate the top cap 30 from both the battery can 20 and the conductive washer 40.

[0098] The insulating member 55 includes a first insulating member 60 provided between the conductive washer 40 and the top cap 30 to electrically insulate the conductive washer 40 from the top cap 30, and a second insulating member 50 provided between the battery can and the top cap to electrically insulate the battery can from the top cap. The insulating member 55 is made of an insulating material.

[0099] The second insulating member 50 is provided between the battery can 20 and the top cap 30 to electrically insulate the battery can from the top cap, and may be, for example, a gasket. The second insulating member 50 may be provided between the crimping portion 22 of the battery can 20 and the top cap 30, which may ensure airtightness of the battery can 20 and electrically insulate the battery can 20 from the top cap 30.

[0100] In the cylindrical secondary battery 1 according to an embodiment of the present invention, the top cap 30 functions as a first electrode terminal having a first polarity, and the conductive washer 40 functions as a second electrode terminal having a second polarity opposite to the first polarity, so that the top cap 30 and the conductive washer 40 must maintain an electrically insulated state. Therefore, a first insulating member 60 may be applied to stably maintain such an insulating state.

[0101] The first insulating member 60 may be provided between the lower surface of the conductive washer 40 and the top cap 30. As described above, the conductive washer 40 has a width D2 larger than the width D1 of the upper surface of the crimping portion 22, and has a shape extending in a direction from the crimping portion 22 toward the protrusion 31 of the top cap 30. Therefore, the first insulating member 60 may have a shape extending to cover the inner surface of a hole formed in the center of the conductive washer 40 so that the inner surface of the hole formed in the conductive washer 40 and the protrusion 31 of the top cap 30 cannot contact each other.

[0102] When the first insulating member 60 is made of a resin material, the first insulating member 60 may be bonded to the conductive washer 40 and the top cap 30 by thermal fusion. In this case, the airtightness at the bonding interface between the first insulating member 60 and the conductive washer 40 and the bonding interface between the first insulating member 60 and the top cap 30 may be enhanced.

[0103] 8, the first insulating member 60 may have a shape extending to cover an area of ​​1% or more, 2% or more, 3% or more, or 4% or more of the total area of ​​the upper surface of the conductive washer 40. The first insulating member 60 may have a shape extending to cover an area of ​​10% or less, 9% or less, 8% or less, or 7% or less of the total area of ​​the upper surface of the conductive washer 40. When this range is satisfied, the effect of preventing contact between the conductive washer 40 and the top cap 30 can be further improved.

[0104] The width C of the first insulating member 60 extending to cover a portion of the upper surface of the conductive washer 40 may be 0.1 mm or more, 0.15 mm or more, 0.2 mm or more, 0.25 mm or more, 0.3 mm or more, or 0.35 mm or more. The width C of the first insulating member 60 extending to cover a portion of the upper surface of the conductive washer 40 may be 3 mm or less, 2.5 mm or less, 2 mm or less, 1.5 mm or less, 1 mm or less, or 0.5 mm or less.

[0105] The width C of the first insulating member 60 extending to cover a part of the upper surface of the conductive washer 40 means the length of the part covered by the first insulating member 60 from the direction of the center of the width D2 of the conductive washer 40 toward the outer periphery. The width D2 of the conductive washer 40 may be set differently depending on the diameter of the secondary battery. The cylindrical secondary battery may be a cell having a substantially cylindrical shape, and the width D2 of the conductive washer 40 may be, for example, 10% or more, 11% or more, 12% or more, or 13% or more of the maximum diameter of the cell. The cylindrical secondary battery may be a cell having a substantially cylindrical shape, and the width D2 of the conductive washer 40 may be, for example, 50% or less, 45% or less, 43% or less, or 40% or less of the maximum diameter of the cell.

[0106] When the first insulating member 60 has a shape extending to the edge region of the upper surface of the conductive washer 40, the process of placing the conductive washer 40 on the crimping unit 22 can be performed more accurately and quickly. After the first insulating member 60 is inserted through a hole in the conductive washer 40 and fixed to the conductive washer 40, the combined body consisting of the conductive washer 40 and the first insulating member 60 is placed on the crimping unit 22 and the top cap 30, so that the conductive washer 40 can be naturally placed at an accurate position. At this time, the protrusion 31 of the top cap 30 is exposed toward the outside of the battery can through a hole formed in the center of the first insulating member 60.

[0107] 8 may be manufactured by insert injection. That is, the combined body of the first insulating member 60 and the conductive washer 40 can be manufactured by insert injection so that the conductive washer 40 made of a metal material is inserted / fixed into the first insulating member 60 made of a resin material, and the combined body can be disposed on the crimping portion 22 and the top cap 30 to provide a natural alignment effect.

[0108] 2 to 7, the current collecting plate 70 is coupled to the upper part of the electrode assembly 10. The current collecting plate 70 is made of a conductive metal material and is coupled to the first electrode tab 11. A lead 72 may be coupled to the current collecting plate 70, and the lead 72 may extend upwardly of the electrode assembly 10 and be directly coupled to the first surface 33 of the top cap 30. Since the top cap 30 has the first surface 33 that can be electrically coupled to the first electrode tab 11, the lead 72 is not coupled to the connecting plate 90 that can be coupled to the first surface 33 of the top cap 30. Since the lead 72 is directly coupled to the first surface 33 of the top cap 30 without being coupled to the connecting plate 90, the number of electrically connected components may be reduced, resulting in a reduction in the resistance of the components.

[0109] 9 and 10, the current collecting plate 70 may include a plurality of sub-plates 71 extending radially from a center portion. The current collecting plate 70 and the lead 72 may be formed integrally. In this case, the lead 72 may have an elongated plate shape extending outward from the center portion of the current collecting plate 70, similar to the sub-plates 71, and may be formed between adjacent sub-plates 71. However, the structure of the current collecting plate 70 of the present invention is not limited thereto, and may have a shape corresponding to the upper surface of the electrode assembly 10 so as to entirely cover the upper portion of the first electrode tab 11.

[0110] Although not shown, the current collecting plate 70 may have a plurality of projections formed radially on its lower surface. When the projections are formed, the current collecting plate 70 can be pressed into the electrode tabs 11 and 12 by pressing the current collecting plate 70.

[0111] 11, the current collecting plate 70 is coupled to an end of the first electrode tab 11. The coupling between the first electrode tab 11 and the current collecting plate 70 may be performed by, for example, laser welding. The laser welding may be performed by partially melting a base material of the current collecting plate 70, or may be performed with solder for welding interposed between the current collecting plate 70 and the first electrode tab 11. In this case, the solder may have a lower melting point than the current collecting plate 70 and the first electrode tab 11.

[0112] 12, the current collecting plate 70 may be coupled to a coupling surface formed by bending an end of the first electrode tab 11 in a direction parallel to the current collecting plate 70. The bending direction of the first electrode tab 11 may be, for example, toward the winding center of the electrode assembly 10. When the first electrode tab 11 has such a folded shape, the space occupied by the first electrode tab 11 is reduced, thereby improving the energy density.

[0113] 13, the current collecting plate 70 may also be coupled to the lower surface of the electrode assembly 10. In this case, one surface of the current collecting plate 70 may be coupled to the second electrode tab 12 of the electrode assembly 10 by welding, and the opposite surface may be coupled to the inner bottom surface of the battery can 20 by welding. The coupling structure of the current collecting plate 70 and the second electrode tab 12 coupled to the lower surface of the electrode assembly 10 is substantially the same as that of the current collecting plate 70 coupled to the upper surface of the electrode assembly 10 described above.

[0114] Although not shown, like the first electrode tab 11, the second electrode tab 12 may also have a shape bent in a direction toward the winding center of the electrode assembly 10.

[0115] The insulating plate 80 is disposed between the upper end of the electrode assembly 10 and the beading portion 21, or between the current collecting plate 70 coupled to the upper portion of the electrode assembly 10 and the beading portion 21, to prevent contact between the first electrode tab 11 and the battery can 20, or between the current collecting plate 70 and the battery can 20.

[0116] The insulating plate 80 has a lead hole 81 through which the lead 72 extending upward from the current collecting plate 70 or the first electrode tab 11 is led out.

[0117] The leads 72 are pulled out upward through lead holes 81 and coupled to the bottom surface of the connection plate 90 or the bottom surface of the top cap 30. As described above, the cylindrical secondary battery 1 according to an embodiment of the present invention has a structure in which the top cap 30 and the conductive washer 40 provided on one side of the battery can 20 in the length direction (parallel to the Z-axis in FIG. 2) can be used as a first electrode terminal and a second electrode terminal, respectively. Therefore, when electrically connecting a plurality of cylindrical secondary batteries 1 according to an embodiment of the present invention, electrical connection parts such as a bus bar can be disposed only on one side of the cylindrical secondary batteries 1, which can simplify the structure and improve the energy density.

[0118] 15, a battery pack 3 according to an embodiment of the present invention includes a secondary battery assembly to which the secondary battery 1 according to an embodiment of the present invention is electrically connected, and a pack housing 2 that accommodates the secondary battery assembly. For convenience of illustration, components such as bus bars and power terminals for electrical connection are omitted in the drawings of the present invention.

[0119] 16, an automobile 5 according to an embodiment of the present invention may be, for example, an electric vehicle, and includes a battery pack 3 according to an embodiment of the present invention. The automobile 5 is operated by receiving power from the battery pack 3 according to an embodiment of the present invention.

[0120] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible within the scope of the technical concept of the present invention and the scope of the claims described below by a person having ordinary knowledge in the technical field to which the present invention belongs.

Claims

1. an electrode assembly including a first electrode tab and a second electrode tab; a battery can having an opening for receiving the electrode assembly and electrically connected to the second electrode tab; a top cap covering the opening of the battery can and electrically connected to the first electrode tab; a conductive washer electrically connected to the battery can and contacting at least a portion of a periphery of the opening; and an insulating member provided between the top cap and at least one of the battery can and the conductive washer electrically connected to the battery can, and electrically insulates the top cap from at least one of the battery can and the conductive washer; Including, the top cap includes a first surface and a second surface facing each other, the first surface facing the electrode assembly and electrically connected to the first electrode tab, and the second surface having a protrusion exposed through a hole formed in a center of the conductive washer; the insulating member includes a first insulating member provided between the conductive washer and the top cap and electrically insulating the conductive washer and the top cap, and a second insulating member provided between the battery can and the top cap and electrically insulating the battery can and the top cap, The first insulating member covers an inner surface of a hole formed in a center of the conductive washer.

2. an electrode assembly including a first electrode tab and a second electrode tab; a battery can having an opening for receiving the electrode assembly and electrically connected to the second electrode tab; a top cap covering the opening of the battery can and electrically connected to the first electrode tab; a conductive washer electrically connected to the battery can and contacting at least a portion of a periphery of the opening; and an insulating member provided between the top cap and at least one of the battery can and the conductive washer electrically connected to the battery can, and electrically insulates the top cap from at least one of the battery can and the conductive washer; Including, the top cap includes a first surface and a second surface facing each other, the first surface facing the electrode assembly and electrically connected to the first electrode tab, and the second surface having a protrusion exposed through a hole formed in a center of the conductive washer; the insulating member includes a first insulating member provided between the conductive washer and the top cap and electrically insulating the conductive washer and the top cap, and a second insulating member provided between the battery can and the top cap and electrically insulating the battery can and the top cap, A secondary battery, wherein the first insulating member extends to cover an area of ​​1% or more and 10% or less of the total area of ​​the upper surface of the conductive washer.

3. an electrode assembly including a first electrode tab and a second electrode tab; a battery can having an opening for receiving the electrode assembly and electrically connected to the second electrode tab; a top cap covering the opening of the battery can and electrically connected to the first electrode tab; a conductive washer electrically connected to the battery can and contacting at least a portion of a periphery of the opening; and an insulating member provided between the top cap and at least one of the battery can and the conductive washer electrically connected to the battery can, and electrically insulates the top cap from at least one of the battery can and the conductive washer; In a secondary battery comprising: the top cap includes a first surface and a second surface facing each other, the first surface facing the electrode assembly and electrically connected to the first electrode tab, and the second surface having a protrusion exposed through a hole formed in a center of the conductive washer; The secondary battery includes a crimped portion on a periphery of an opening of the battery can, and the conductive washer is in contact with the crimped portion; The battery can includes an insertion groove provided on an upper surface of the crimping portion.

4. The secondary battery according to any one of claims 1 to 3, wherein the top cap includes a non-protruding portion that is not provided with the protruding portion, and the height of the protruding portion from the first surface is formed to be greater than the height of the non-protruding portion from the first surface.

5. The secondary battery according to claim 1 , wherein the top cap contains aluminum.

6. The secondary battery according to any one of claims 1 to 5, wherein the battery can is cylindrical.

7. The secondary battery according to claim 1 , wherein the first insulating member is coupled to the conductive washer and the top cap by thermal fusion.

8. The secondary battery according to claim 1 or 2, wherein the secondary battery has a crimped portion on a periphery of an opening of the battery can, and the conductive washer is in contact with the crimped portion.

9. The secondary battery according to claim 3 , wherein a width of the conductive washer is greater than a width of an upper surface of the crimping portion.

10. The secondary battery according to claim 3 or 9, wherein the sum of the thickness of the crimping portion at the portion in contact with the conductive washer and the thickness of the conductive washer in contact with the crimping portion is 90% to 200% of the thickness of the conductive washer not in contact with the crimping portion.

11. The secondary battery according to claim 3 , wherein the conductive washer includes an insertion protrusion having a shape corresponding to the insertion groove and coupled to the insertion groove.

12. The secondary battery according to claim 1 , wherein the battery can includes a vent portion formed on a lower surface thereof.

13. 13. The secondary battery of claim 1, wherein the first electrode tab is an uncoated portion of a first electrode collector constituting the electrode assembly where a first electrode active material is not formed, and the second electrode tab is an uncoated portion of a second electrode collector constituting the electrode assembly where a second electrode active material is not formed.

14. The secondary battery of claim 1 , wherein the first electrode tab and the second electrode tab are bent toward a winding center of the electrode assembly.

15. A secondary battery; and A pack housing for accommodating the secondary battery wherein the secondary battery is the secondary battery according to any one of claims 1 to 14.

16. 16. A vehicle comprising the battery pack of claim 15.

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