Secondary battery, battery pack including the same, and automobile

Abstract

The present specification provides a secondary battery, and a battery pack and automobile including the same, comprising: an electrode assembly in which a first electrode, a second electrode, and a separator provided therebetween are wound up, wherein the long side ends of the first electrode and the second electrode are not coated with an active material and include an uncoated portion of the first electrode exposed to the outside of the separator; and a current collector plate provided at one end of the electrode assembly where the uncoated portion of the first electrode is exposed, the current collector plate including a central portion corresponding to the winding core of the electrode assembly; and a peripheral portion provided around the central portion and in contact with one end of the electrode assembly, the peripheral portion including one or more first through holes through which at least a portion of the uncoated portion of the first electrode passes.

Description

[Technical field]

[0001] This specification claims the benefit of the filing date of Korean Patent Application No. 10-2021-0022865, filed with the Korean Intellectual Property Office on February 19, 2021, the entire contents of which are incorporated herein by reference.

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

[0003] Secondary batteries, which have a high degree of ease of application to various products and have electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs, Electric Vehicles) and hybrid electric vehicles (HEVs, Hybrid Electric Vehicles) that are powered by electrical 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 attracting attention as a new energy source that is environmentally friendly and can improve energy efficiency.

[0005] Currently, the types of secondary batteries that are widely used 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 about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a battery pack is constructed by connecting a plurality of batteries in series. Also, a battery pack may be constructed by connecting a number of batteries in parallel depending on the charge / discharge capacity required for the battery pack. Therefore, the number of batteries included in the battery pack and the electrical connection form can be variously set depending on the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, cylindrical, prismatic and pouch-type batteries are known as types of secondary battery cells. In the case of cylindrical batteries, a separator, which is an insulator, is interposed between the positive and negative electrodes, and this is rolled up to form a jelly-roll type electrode assembly, which is then inserted into a battery can together with an electrolyte to form a battery. For reference, the positive electrode terminal is the cap of the sealing body that seals the opening of the battery can, and the negative electrode terminal is the battery can.

[0007] As shown in Figure 8, when welding the electrode assembly and the current collector plate for electrical connection, there is a problem that the heat input is high in the area where the uncoated part abuts the current collector plate due to the unevenness in the height of the uncoated part, causing the current collector plate to melt and generate welding spatters. The welding spatters remain inside the secondary battery as metallic foreign matter and can cause low-voltage failure due to micro-short circuits. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a secondary battery having a structure capable of ensuring a uniform contact area in a welding region in order to reduce welding spatter. [Means for solving the problem]

[0009] The present specification provides a secondary battery comprising: an electrode assembly in which a first electrode and a second electrode and a separator provided therebetween are wound up, wherein the long side end portions of the first electrode and the second electrode are not coated with an active material and include an uncoated portion of the first electrode exposed to the outside of the separator; and a current collector provided at one end of the electrode assembly where the uncoated portion of the first electrode is exposed, the current collector including a central portion corresponding to a winding core of the electrode assembly and a peripheral portion provided around the central portion and in contact with one end of the electrode assembly, wherein the peripheral portion includes one or more first through holes provided so that at least a portion of the uncoated portion of the first electrode passes through.

[0010] In one embodiment of the present specification, the central portion of the current collector plate may further include a central hole provided in a portion corresponding to the winding core of the electrode assembly.

[0011] In one embodiment of the present specification, the uncoated portion of the first electrode exposed to the outside through the first through hole of the current collector plate may be folded one or more times in a winding core direction of the electrode assembly.

[0012] In one embodiment of the present specification, the peripheral portion of the current collector plate may include two or more first through holes spaced apart in the winding direction of the electrode assembly.

[0013] In one embodiment of the present specification, the peripheral portion of the collector plate may include one or more first through hole groups including two or more first through holes spaced apart from the central portion in any one outer periphery direction.

[0014] In one embodiment of the present specification, the first through-hole group may include two to six first through-holes spaced apart from the center toward any one of the outer edges.

[0015] In one embodiment of the present specification, the peripheral portion of the current collector plate may include two to six of the first through hole groups, and each of the first through hole groups may be arranged spaced apart from each other in the winding direction of the electrode assembly.

[0016] In one embodiment of the present specification, the peripheral portion of the collector plate may include two of the first groups of through holes, and the two first groups of through holes may be arranged opposite each other across the central portion.

[0017] In one embodiment of the present specification, the peripheral portion of the current collector plate may include three to six of the first through hole groups, and each of the first through hole groups may be arranged spaced apart from each other in the winding direction of the electrode assembly.

[0018] In one embodiment of the present specification, at least one of the first through holes may be provided in contact with an edge of the current collector plate.

[0019] In one embodiment of the present specification, the first through-hole may be in the form of a slit or a dot.

[0020] In one embodiment of the present specification, the peripheral portion of the current collector plate may further include one or more second through holes.

[0021] In one embodiment of the present specification, the peripheral portion of the current collector plate includes two or more first groups of through holes, and the peripheral portion of the current collector plate further includes one or more second through holes, and the second through holes may be provided between two adjacent groups of the first through holes.

[0022] In one embodiment of the present specification, the current collector plate may further include an electrode tab.

[0023] The present specification provides a battery pack including a plurality of the above-described secondary batteries.

[0024] The present disclosure provides a vehicle including at least one battery pack as described above. Effect of the Invention

[0025] A secondary battery according to one embodiment of the present specification has a structure in which at least a portion of the uncoated electrode portion of the electrode assembly penetrates the current collector plate, and the uncoated electrode portion exposed to the outside is bent, thereby ensuring a uniform welding area during the welding process between the current collector plate and the electrode assembly.

[0026] In addition, by irradiating a laser beam onto the folded electrode uncoated portion having a relatively thin thickness during the welding process, there is an additional advantage that the laser irradiation energy can be reduced. [Brief description of the drawings]

[0027] [Figure 1] FIG. 2 is a plan view showing the structure of a plate-shaped electrode before winding according to one embodiment of the present specification. [Diagram 2] 1A to 1C are diagrams illustrating a winding process of an electrode assembly according to an embodiment of the present specification. [Diagram 3] 3 is an assembly diagram showing a process in which current collector plates are provided on both ends of the uncoated portion after the electrode assembly in FIG. 2 is wound. [Figure 4] FIG. 1 is a cross-sectional view of a secondary battery according to an embodiment of the present specification, cut in the longitudinal direction (Y). [Diagram 5] 11 is a cross-sectional view showing a riveting structure of an electrode terminal according to still another embodiment of the present specification. [Figure 6] 6 is a cross-sectional view of a portion indicated by a dotted circle (B) in FIG. 5. [Figure 7] FIG. 2 is a cross-sectional view of a secondary battery according to still another embodiment of the present specification, cut along the longitudinal direction (Y). [Figure 8] 13 is a diagram showing an area where the uncoated portion does not come into contact with the current collecting plate due to variations in height of the uncoated portion. FIG. [Figure 9] FIG. 2 is a diagram illustrating a central hole, a first through hole, a second through hole, and a first electrode uncoated portion exposed through the first through hole in a current collector plate according to one embodiment of the present specification. [Figure 10] FIG. 2 is a diagram showing a state in which a first electrode uncoated portion according to an embodiment of the present specification is exposed to the outside of a current collector plate and then bent. [Figure 11] FIG. 2 is a plan view illustrating an example of a plate-shaped electrode structure before winding according to another embodiment of the present specification. [Figure 12] FIG. 11 is a cross-sectional view taken along the longitudinal direction (Y) of an electrode assembly in which a segmented structure of an uncoated portion of an electrode according to another embodiment of the present specification is applied to a first electrode and a second electrode. [Figure 13] 1 is a cross-sectional view of an electrode assembly in which an uncoated portion according to another embodiment of the present specification is folded along a longitudinal direction (Y). [Figure 14] FIG. 1 is a diagram showing a schematic configuration of a battery pack including a cylindrical battery cell according to one embodiment of the present specification. [Figure 15] FIG. 1 is a diagram showing a schematic configuration of an automobile including a battery pack according to an embodiment of the present specification. [Figure 16] 1A to 1C are diagrams illustrating various forms of a current collector plate according to an embodiment of the present specification. [Figure 17] 1A to 1C are diagrams illustrating various forms of a current collector plate according to an embodiment of the present specification. [Figure 18] 1A to 1C are diagrams illustrating various forms of a current collector plate according to an embodiment of the present specification. [Figure 19] 1A to 1C are diagrams illustrating various forms of a current collector plate according to an embodiment of the present specification. [Figure 20] 1A to 1C are diagrams illustrating various forms of a current collector plate according to an embodiment of the present specification. [Figure 21] 1A to 1C are diagrams illustrating various forms of a current collector plate according to an embodiment of the present specification. [Figure 22] 1A to 1C are diagrams illustrating various forms of a current collector plate according to an embodiment of the present specification. [Figure 23] 1A to 1C are diagrams illustrating various forms of a current collector plate according to an embodiment of the present specification. [Figure 24] 1A to 1C are diagrams illustrating various forms of a current collector plate according to an embodiment of the present specification. [Explanation of symbols]

[0028] 10: First electrode 10a: Uncoated portion of the first electrode 11: second electrode 11a: uncoated portion of second electrode 12: Separator 30, 31: Current collector plate 71, A, 100: Electrode assembly Y: Longitudinal direction X: Winding direction Z: Outer direction 40, 70: Secondary battery 41, 51: Battery can 42, 74: Sealing body 42a, 74a: Cap plate 42b, 74b: Sealing gasket 42c: Connection plate 43, 75: Crimping section 44, 76: Beading section 45: Lead 46: Insulator 50: Electrode terminal 50a: Body part 50b: External flange portion 50c: Internal flange portion 50d: Flat part 52: Bottom of battery can 52a: outer surface of bottom of battery can 52b: inner surface of the bottom of the battery can 53:Through hole 54: Rivet gasket 54a: External gasket 54b: Internal gasket 55: Recessed part 55a: Side wall of flat section 55b: Inclined surface of internal flange 56: Inner edge of through hole 57: The surface facing the internal flange H1: Height of flat part H2: Height of the inner gasket edge H3: Height of the end of the internal flange R1: Radius from the center of the body to the edge of the outer flange R2: Radius of the bottom of the battery can R3: Radius from the center of the body to the edge of the flat part 72: Uncoated portion of the second electrode 73: Uncoated portion of the first electrode 76a: Inner surface of beading part 77: Bent notch 78: Second current collector 78a: At least a portion of the edge of the second electrode that is not in contact with the uncoated portion 79: First current collector 80: Hollow 90: Electrode 91: Current collector 92: Active material layer 93: Plain area 93': Plain area on core side 93a: segment h: height of segment r: radial length of the winding area formed by the uncoated portion on the core side 94: Insulating coating layer 101: Foldable part 102: Bent surface 200: Battery pack 201: Cylindrical battery cell 202: Pack housing V: Automobiles 300: Electrode assembly 311: Uncoated portion of the first electrode 320: Recess 330:Protrusion 340: Core 400: Current collector plate 410: Center 411: Center hole 420: Surrounding area 430, 431-1, 431-2, 431-3, 432-1, 432-2, 432-3, 433-1, 433-2, 433-3, 434-1, 434-2, 434-3: first through hole 431, 432, 433, 434: first through hole group 440: Second through hole 450: Electrode tab a: Core direction b: Outer direction DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] This specification will be explained in more detail below.

[0030] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, 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 that are consistent with the technical ideas of the present invention, based on the principle that the inventor can appropriately define the concepts of terms in order to best describe his / her invention. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are only some of the most preferred embodiments of the present invention, and do not fully represent the technical ideas of the present invention, and therefore there may be various equivalents and modifications that can replace them at the time of this application.

[0031] In order to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0032] A statement that two comparison objects are identical means that they are "substantially identical." Therefore, substantially identical can include cases where there is a difference that is considered to be a low level in the art, for example, a difference within 5%. In addition, a certain parameter being uniform in a given region can mean that it is uniform from an average perspective.

[0033] As used herein, "on" does not mean only being physically on top of a layer, but also means being located on or above a position, i.e., a layer located on any one layer may have other layers therebetween.

[0034] In this specification, when a part is said to "comprise" a certain component, this does not mean that it excludes other components, but that it can further include other components, unless specifically stated to the contrary.

[0035] A secondary battery 40 , 70 according to an embodiment of the present specification includes an electrode assembly 300 and a current collector plate 400 .

[0036] One embodiment of the present specification is an electrode assembly 71, A, 100 in which a first electrode 10, a second electrode 11, and a separator 12 provided therebetween are wound, and the first electrode 10 and the second electrode 11 each include a non-coated portion 311 that is not coated with an active material at a long side end and is exposed to the outside of the separator 12; and one of the electrode assemblies 71, A, 100 in which the non-coated portion 311 of the first electrode 10 is exposed. The secondary battery (40, 70) includes a current collector plate (400) provided at an end, the current collector plate (400) including a central portion (410) corresponding to the winding core (340) of the electrode assembly (71, A, 100), and a peripheral portion (420) provided around the central portion (410) and in contact with one end of the electrode assembly (71, A, 100), the peripheral portion (420) including one or more first through holes (430) provided so that at least a portion of the uncoated portion (311) of the first electrode (10) penetrates therethrough.

[0037] In one embodiment of the present specification, the current collector 400 includes a central portion 410 provided at one end of the electrode assembly 71, A, 100 where the uncoated portion 311 of the first electrode 10 is exposed, and corresponds to the winding core 340 of the electrode assembly 71, A, 100; and a peripheral portion 420 provided around the central portion 410 and in contact with one end of the electrode assembly 71, A, 100, and the peripheral portion 420 includes one or more first through holes 430 provided so that at least a portion of the uncoated portion 311 of the first electrode 10 passes through.

[0038] When the electrode assembly 71, A, 100 and the current collector plate 400 are combined, the first through-hole 430 serves as a passage through which the uncoated portion 311 of the first electrode 10 penetrates the current collector plate 400. In FIG. 9, the uncoated portion 311 of the first electrode 10 penetrates the current collector plate 400 through the first through-hole 430.

[0039] The uncoated portion 311 of the first electrode of the electrode assemblies 71 , A, and 100 may be at least partially cut according to the shape of the first through-hole 430 of the current collector plate 400 .

[0040] In one embodiment of the present specification, the center portion 410 of the current collector plate 400 may further include a center hole 411 provided in a portion corresponding to the winding core 340 of the electrode assembly 71, A, 100. Various embodiments in which the center hole 411 is provided are illustrated in Fig. 9 and Figs. 16 to 19.

[0041] The central hole 411 may have a circular shape or a shape in which straight lines and curved lines are connected.

[0042] In one embodiment of the present specification, the uncoated portion 311 of the first electrode 10 exposed to the outside through the first through hole 430 of the current collector 400 may be folded one or more times in the winding core direction (a) of the electrode assembly 71, A, 100.

[0043] In one embodiment of the present specification, the uncoated portion 311 of the first electrode 10 exposed to the outside through the first through hole 430 of the current collector 400 may be folded two or more times in the winding core direction (a) of the electrode assembly 71, A, 100.

[0044] In one embodiment of the present specification, at least one surface of the uncoated portion of the first electrode exposed to the outside through the first through-hole 430 and bent one or more times may be in contact with the upper part of the current collector plate 400. At this time, the uncoated portion 311 of the first electrode 10 includes a protrusion 330 corresponding to the first through-hole 430 and a recess 320 cut in a concave shape to allow the protrusion 330 to protrude. The protrusion 330 is penetrated through the first through-hole 430 and then bent in the winding core direction (a) of the electrode assembly 71, A, 100 and fastened. The protrusion 330 fastened in this manner is fixed by welding using a laser. FIG. 10 shows the uncoated portion 311 of the first electrode 10 bent one or more times.

[0045] In contrast, the recess 320 contacts the lower part of the current collecting plate 400 where the first and second through holes 430, 440 are not formed, and the end of the uncoated portion 311 of the first electrode 10 becomes uniform by cutting, so that the recess 320 and the lower part of the current collecting plate 400 can contact each other uniformly without any variation in height.

[0046] The welding process between the electrode assembly 71, A, 100 and the current collector plate 400 is performed by irradiating a laser onto the uncoated portion 311 of the first electrode 10 that is exposed to the outside through the first through hole 430 and bent.

[0047] At this time, the non-coated portion 311 of the first electrode 10 irradiated with the laser is relatively thinner than the current collector plate 400, which is advantageous in that the energy of the laser irradiation can be reduced.

[0048] In one embodiment of the present specification, the peripheral portion 420 of the current collector plate 400 may include two or more first through holes 431-1, 431-2, 431-3, 432-1, 432-2, 432-3, 433-1, 433-2, 433-3, 434-1, 434-2, 434-3 spaced apart in the winding direction (X) of the electrode assembly 71, A, 100. The winding direction (X) of the electrode assembly means the direction in which the electrode assembly is wound with respect to the winding shaft. Figures 16 to 24 show examples of positions where the first through holes 430 are arranged in the peripheral portion 420.

[0049] The peripheral portion 420 of the current collector plate 400 may include three or more first through holes 430 spaced apart in the winding direction (X) of the electrode assembly 71, A, 100.

[0050] The peripheral portion 420 of the current collector plate 400 may include four or more first through holes 430 spaced apart in the winding direction (X) of the electrode assembly 71, A, 100.

[0051] The peripheral portion 420 of the current collector plate 400 may include nine or more first through holes 430 spaced apart in the winding direction (X) of the electrode assembly 71, A, 100.

[0052] The peripheral portion 420 of the current collector plate 400 may include twelve or more first through holes 430 spaced apart in the winding direction (X) of the electrode assembly 71, A, 100.

[0053] In one embodiment of the present specification, the peripheral portion 420 of the current collecting plate 400 may include one or more first through hole groups 431 including two or more first through holes 430 spaced apart from the central portion 410 in any one of the outer periphery directions (b). That is, the two or more first through holes 430 belonging to the first through hole group 431 may have different shortest distances from the central portion. FIGS. 16 to 24 illustrate examples in which the first through hole groups 431 are arranged in the peripheral portion 420 in various structures.

[0054] In one embodiment of the present specification, the first through hole group 431 may include two to six first through holes 430. That is, in the present specification, one first through hole group 431 may include two to six first through holes 430, and the two to six first through holes 430 belonging to the first through hole group 431 may have mutually different shortest distances from the center portion 410.

[0055] In one embodiment of the present specification, the first through-hole group 431 may include two to five first through-holes 430.

[0056] In one embodiment of the present specification, the first through-hole group 431 may include two to four first through-holes 430.

[0057] In one embodiment of the present specification, the first through-hole group 431 may include two or three first through-holes 430.

[0058] In one embodiment of the present specification, as shown in Figures 16, 17, 20(a), 20(b), 21(a) and 21(b), the first through-hole group 431, 432 may include two first through-holes 431-1, 431-2, 432-1, 432-2.

[0059] In one embodiment of the present specification, as shown in Figures 18 and 19, the first through-hole groups 431, 432, and 433 may include three first through-holes 431-1, 431-2, 431-3, 432-1, 432-2, 432-3, 433-1, 433-2, and 433-3.

[0060] In one embodiment of the present specification, as shown in Figures 22 to 24, the first through-hole groups 431, 432, 433, 434 may include four first through-holes 431-1, 431-2, 431-3, 432-1, 432-2, 432-3, 433-1, 433-2, 433-3, 434-1, 434-2, 434-3.

[0061] In one embodiment of the present specification, the peripheral portion 420 of the collector plate 400 includes two to six of the first through hole groups 431, and each of the first through hole groups 431 may be spaced apart in the winding direction (X) of the electrode assembly 71, A, 100.

[0062] In one embodiment of the present specification, the peripheral portion 420 of the collector plate 400 includes two of the first through hole groups 431, and the two first through hole groups 431, 432 may be arranged to face each other across the central portion 410, as shown in Figures 16, 17, 20(a), 20(b), 21(a) and 21(b).

[0063] In one embodiment of the present specification, the peripheral portion 420 of the collector plate 400 includes three to six of the first through hole groups 431, and each of the first through hole groups 431 may be arranged spaced apart from each other in the winding direction (X) of the electrode assembly 71, A, 100.

[0064] In one embodiment of the present specification, at least one of the first through holes 430 may be provided in contact with an edge of the current collector plate 400 .

[0065] In one embodiment of the present specification, the first through-hole 430 may be in the form of a slit or a dot. The slit may have at least two curves having different radii of curvature. The dot may have a shape such as a rectangular square or a trapezoid, but is not limited thereto.

[0066] In one embodiment of the present specification, the peripheral portion 420 of the current collector plate 400 may further include one or more second through holes 440. The second through holes 440 are used for electrolyte injection purposes.

[0067] In one embodiment of the present specification, the peripheral portion 420 of the collector plate 400 further includes one or more second through holes 440, and the second through holes 440 may be provided between two adjacent groups of the first through holes 431.

[0068] That is, the second through-hole 440 may be provided spaced apart from the central hole 411 and the first through-hole 430 .

[0069] In one embodiment of the present specification, the current collector plate 400 may further include an electrode tab 450. When the electrode tab 450 is provided, the electrode tab 450 is bent and connected according to the structure of the battery cell when the battery cell is assembled.

[0070] A secondary battery 40, 70 according to an embodiment of the present specification is an electrode assembly 71, A, 100 configured by stacking and winding a first electrode 10, a separator 12, and a second electrode 11, and the first electrode 10 includes a first electrode collector (not shown) and an electrode active material layer (not shown) provided on the first electrode collector (not shown), and a long side end portion along the winding direction (X) of the first electrode collector (not shown) is the electrode active material layer (not shown). an electrode assembly (71, A, 100) including an uncoated portion (10a) of a first electrode (10) not provided with a barrier layer; and a current collector (400) provided at one end of the electrode assembly (71, A, 100) where the uncoated portion (10a) of the first electrode (10) is exposed, the current collector (400) including a central portion (410) corresponding to the winding core (340) of the electrode assembly (71, A, 100), the central portion (410) including a first welded portion having a thickness thinner than the remaining thickness of the current collector (400).

[0071] In one embodiment of the present specification, the ratio of the average thickness of the first welded portion to the thickness of the current collector plate excluding the first welded portion may be 0.4:1 to 0.9:1. The ratio of the average thickness of the first welded portion to the thickness of the current collector plate 400 excluding the first welded portion may be 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, or 0.9:1.

[0072] In one embodiment of the present specification, the current collecting plate 400 may include a central portion 410 including a first welded portion (not shown) and a peripheral portion 420 separated therefrom, and the entire edge of the peripheral portion 420 may extend in the outer periphery direction (Z) of the electrode assembly 300. The current collecting plate 400 having such a shape may have a shape such as a disk shape or an ellipse shape. The peripheral portion 420 may include a second welded portion having a thickness thinner than the remaining portion excluding the first welded portion.

[0073] In yet another embodiment of the present specification, a part of the edge of the central portion 410 may include one or more legs extending in the outer periphery direction (Z) of the electrode assembly 300. That is, the peripheral portion 420 may include a second welded portion having a thickness thinner than the remaining thickness excluding the first welded portion.

[0074] In one embodiment of the present specification, the ratio of the average thickness of the second welded portion to the thickness of the current collector plate excluding the first welded portion and the second welded portion may be 0.4: 1 to 0.9: 1. The ratio of the average thickness of the second welded portion to the thickness of the current collector plate excluding the first welded portion and the second welded portion may be 0.4: 1, 0.5: 1, 0.6: 1, 0.7: 1, 0.8: 1, or 0.9: 1.

[0075] FIG. 1 shows the structure of a current collector according to one embodiment of the present specification, FIG. 2 shows a winding process of an electrode assembly 71, A, 100 including electrodes 10, 11 and a separator 12 according to one embodiment of the present specification, and FIG. 3 shows a process of welding a current collector plate to the folded surface of a non-coated portion 10a according to one embodiment of the present specification.

[0076] FIG. 4 shows a structure in which a strip-shaped lead 45 is used to connect a current collector 400 and an electrode terminal 50 in a secondary battery.

[0077] 1 to 4, the first electrode 10 and the second electrode 11 have a structure in which an active material is coated on a sheet-shaped current collector 91 to provide an active material layer 92, and include a non-coated portion 93 on one long side along the winding direction.

[0078] The electrode assembly is produced by sequentially stacking a first electrode 10 and a second electrode 11 together with two separators 12 as shown in Fig. 2, and then winding them up in one direction (X). At this time, the uncoated portions of the first electrode 10 and the second electrode 11 are arranged in opposite directions. After the winding process, the uncoated portion 10a of the first electrode 10 and the uncoated portion 11a of the second electrode 11 are folded toward the core. Thereafter, as shown in Fig. 3, the current collectors 30 and 31 are welded to the uncoated portions 10a and 11a, respectively, to join them.

[0079] Since no separate electrode tabs are attached to the uncoated area 10a of the first electrode and the uncoated area 11a of the second electrode, and the current collecting plates 30, 31 are connected to external electrode terminals, and a current path is formed with a large cross-sectional area along the winding axis direction of the electrode assembly A (see arrow), it has the advantage of being able to reduce the resistance of the battery cell. This is because resistance is inversely proportional to the cross-sectional area of ​​the path through which the current flows.

[0080] A secondary battery 40 according to an embodiment of the present specification includes a battery can 41 and a sealing body 42, as shown in Fig. 4. The sealing body 42 includes a cap plate 42a, a sealing gasket 42b, and a connection plate 42c. The sealing gasket 42b is fixed by a crimping portion 43 while wrapping the edge of the cap plate 42a. In addition, the electrode assembly A is fixed in the battery can 41 by a beading portion 44 to prevent up and down movement.

[0081] Typically, the positive electrode terminal is the cap plate 42a of the sealing body 42, and the negative electrode terminal is the battery can 41. Thus, the current collector 30 coupled to the uncoated portion 10a of the first electrode 10 is electrically connected to a connection plate 42c attached to the cap plate 42a through a strip-shaped lead 45. Also, the current collector 31 coupled to the uncoated portion 11a of the second electrode 11 is electrically connected to the bottom of the battery can 41. The insulator 46 covers the current collector 30 to prevent the battery can 41 and the uncoated portion 10a of the first electrode 10, which have different polarities, from coming into contact with each other and causing a short circuit.

[0082] Referring to FIG. 4, when the current collector 30 is connected to the connection plate 42c, a strip-shaped lead 45 is used. The lead 45 is attached separately to the current collector 30 or is manufactured integrally with the current collector 30. However, since the lead 45 is a thin strip-shaped lead, its cross-sectional area is small, and a large amount of heat is generated when a fast charging current flows. In addition, the excessive heat generated in the lead 45 is transferred to the electrode assembly A side and may cause the separator 12 to shrink, resulting in an internal short circuit, which is the main cause of thermal runaway. The lead 45 also occupies a considerable installation space within the battery can 41. Therefore, the secondary battery 40 including the lead 45 has low space efficiency and is limited in increasing the energy density.

[0083] In one embodiment of the present specification, the first electrode includes a current collector and an electrode active material layer provided on one or both sides of the current collector. The current collector is provided at one end of a winding shaft of the electrode assembly, and the long side end along the winding direction has an uncoated portion of the first electrode (hereinafter, referred to as the first uncoated portion) that is not provided with an electrode active material layer. The first uncoated portion is provided at the upper portion in the height direction (direction parallel to the Z axis) of the electrode assembly contained in the battery can. That is, the current collector includes the uncoated portion of the first electrode that is not coated with the electrode active material at the long side end and is exposed to the outside of the separator.

[0084] In one embodiment of the present specification, the second electrode includes a second electrode collector and a second electrode active material layer provided on one or both sides of the second electrode collector. An uncoated portion of the second electrode (hereinafter, second uncoated portion) not including the second electrode active material layer is present at the other end of the second electrode collector in the width direction (direction parallel to the Z axis).

[0085] The uncoated portion of the second electrode is provided at the lower portion in the height direction (direction parallel to the Z-axis) of the electrode assembly housed in the battery can. That is, the second electrode current collector includes a second uncoated portion that is not coated with an electrode active material layer at a long side end and is exposed to the outside of the separator, and at least a portion of the second uncoated portion can be used as an electrode tab by itself. The second uncoated portion may be, for example, a negative electrode tab.

[0086] In one embodiment of the present specification, the electrode assembly may include a welding target area, which is an area where the number of overlapping layers of the segmented pieces of the uncoated portion of the second electrode remains constant along the radial direction of the electrode assembly.

[0087] In this region, the number of overlapping layers is kept at a maximum, so it is advantageous to perform welding between the second current collecting plate and the uncoated portion of the second electrode, which will be described later, in this region. When applying laser welding, if the laser output is increased to improve welding quality, it is possible to prevent the laser beam from penetrating the uncoated portion of the second electrode and damaging the electrode assembly. In addition, it is possible to effectively prevent foreign matter such as welding spatter from entering the inside of the electrode assembly.

[0088] In one embodiment of the present specification, the first uncoated portion and the second uncoated portion extend in opposite directions to each other along the height direction (direction parallel to the Z-axis) of the secondary battery. The first uncoated portion extends toward the closed portion of the battery can, and the second uncoated portion extends toward the open portion of the battery can.

[0089] In one embodiment herein, the first electrode may be a negative electrode and the second electrode may be a positive electrode.

[0090] In one embodiment herein, the first electrode may be a positive electrode and the second electrode may be a negative electrode.

[0091] In one embodiment of the present specification, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode may be any active material known in the art without limitation.

[0092] In one example, the positive electrode active material has the general chemical formula A[A x M y ]O 2+z (A includes at least one element selected from Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, −0.1≦z≦2; the stoichiometric coefficients x, y, and z are selected such that the compound maintains electrical neutrality).

[0093] In another example, the positive electrode active material is an alkali metal compound xLiM disclosed in US 6,677,082, US 6,680,143, etc. 1 O2-(1-x)Li2M 2 O3(M 1 contains at least one element having an average oxidation state of 3; M 2 may contain at least one element having an average oxidation state of 4; 0≦x≦1).

[0094] In another example, the positive electrode active material has the general chemical formula Li a M 1 x Fe 1-x M 2 y P 1-y M 3 z O 4-z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V, and S; M 3containing a halogen group element selectively containing F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; the stoichiometric coefficients a, x, y, and z are selected so that the compound maintains electrical neutrality), or may be a lithium metal phosphate represented by Li3M2(PO4)3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al].

[0095] Preferably, the positive electrode active material can contain primary particles and / or secondary particles formed by aggregation of primary particles.

[0096] In one example, as the negative electrode active material, a carbon material, a lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. can be used. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V can also be used as the negative electrode active material. As the carbon material, both low-crystalline carbon and / or high-crystalline carbon can be used.

[0097] In one embodiment of the present specification, the separator can be a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., used alone or laminated. As another example, the separator can usually be a porous non-woven fabric, for example, a non-woven fabric made of high-melting glass fibers, polyethylene terephthalate fibers, etc.

[0098] At least one surface of the separator can include a coating layer of inorganic particles. Also, the separator itself can be composed of a coating layer of inorganic particles. The particles constituting the coating layer can have a structure in which they are bonded to a binder so that an interstitial volume exists between adjacent particles.

[0099] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. As a non-limiting example, the inorganic particles may be Pb(Zr,Ti)O3 (PZT), Pb 1-x La x ZR 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0100] The electrolyte is A + B - The salt may have the structure: + Li + , Na + , K + and combinations of these cations. - is F - , Cl - , B.R. - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO- , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - The anion includes one or more anions selected from the group consisting of:

[0101] The electrolyte may also be dissolved in an organic solvent, such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0102] The secondary battery of the present specification may further include a battery can that houses the electrode assembly and has an opening; a cap plate that is configured to seal the opening of the battery can; and an electrode terminal that is welded and coupled to the first welded portion of the current collector plate and riveted to the battery can.

[0103] A secondary battery according to an embodiment of the present specification includes a cylindrical battery can 51 that houses an electrode assembly 71 and is electrically connected to an uncoated portion 72 of a second electrode. Preferably, one side (lower portion) of the battery can 51 is open. In addition, a bottom 52 of the battery can 51 has a structure in which an electrode terminal 50 is riveted to a through-hole 53 through a crimping process.

[0104] In one embodiment of the present specification, the secondary battery may include a gasket interposed between the electrode terminal and the through hole.

[0105] In one embodiment of the present specification, the secondary battery 70 may also include a sealing body 74 that seals the open end of the battery can 51 so as to be insulative from the battery can 51. Preferably, the sealing body 74 may include a cap plate 74a having no polarity and a sealing gasket 74b interposed between an edge of the cap plate 74a and the open end of the battery can 51.

[0106] In this specification, the cap plate 74a may be made of a conductive metal material such as aluminum, steel, nickel, etc. Also, the sealing gasket 74b may be made of insulating and elastic polypropylene, polybutylene terephthalate, polyethylene fluoride, etc. However, the present invention is not limited by the materials of the cap plate 74a and the sealing gasket 74b.

[0107] In one embodiment of the present disclosure, the cap plate 74a may include vent notches 77 that rupture when the pressure inside the battery can 51 exceeds a threshold value. The vent notches 77 may be formed on both sides of the cap plate 74a. The vent notches 77 may form a continuous or discontinuous circular pattern, linear pattern, or other pattern on the surface of the cap plate 74a.

[0108] In one embodiment of the present specification, the battery can 51 may include a crimping portion 75 that extends and is bent toward the inside of the battery can 51 to wrap around and fix the edge of the cap plate 74a together with the sealing gasket 74b in order to fix the sealing body 74.

[0109] In one embodiment of the present specification, the battery can 51 may also include a beading portion 76 press-fitted into the inside of the battery can 51 in a region adjacent to the open end. The beading portion 76 supports the edge of the sealing body 74, particularly the outer peripheral surface of the sealing gasket 74b, when the sealing body 74 is fixed by the crimping portion 75.

[0110] In one embodiment of the present specification, the electrode terminal is made of a conductive metal material, and aluminum (Al) may be used.

[0111] In one embodiment of the present specification, the secondary battery may further include a second current collector 78 welded to the uncoated portion 72 of the second electrode. The second current collector 78 is made of a conductive metal material such as aluminum, steel, or nickel.

[0112] In one embodiment of the present specification, the second current collector 78 can be fixed by the crimping portion 75 with at least a portion 78a of its edge that is not in contact with the uncoated portion 72 of the second electrode being interposed between the beading portion 76 and the sealing gasket 74b.

[0113] Alternatively, at least a portion 78a of the edge of the second current collector 78 may be fixed to the inner circumferential surface 76a of the beading portion 76 adjacent to the crimping portion 75 through welding.

[0114] In one embodiment of the present specification, an insulator may be provided between the current collector plate and an inner surface of the battery can. The insulator prevents contact between the current collector plate and the battery can. The insulator may also be interposed between an upper end of an outer circumferential surface of the electrode assembly and an inner surface of the battery can. That is, the insulator may also be interposed between an uncoated portion of the first electrode and an inner surface of a sidewall portion of the battery can. This is to prevent contact between an uncoated portion of the first electrode extending toward a closing portion of the battery can and an inner circumferential surface of the battery can.

[0115] In one embodiment of the present specification, the uncoated portions 72, 73 of the first electrode and / or the second electrode may be bent from the outer periphery side of the electrode assembly 71 toward the core side to form bent surfaces at the upper and lower parts of the electrode assembly 71. In addition, the second current collecting plate 78 may be welded to the bent surface formed by bending the uncoated portion 72 of the second electrode, and the first current collecting plate 79 may be welded to the bent surface formed by bending the uncoated portion 73 of the first electrode.

[0116] In order to relieve stress generated when the uncoated portions 72 and 73 are folded, the first electrode and / or the second electrode may have an improved structure different from that of the electrode according to Fig. 1. Fig. 11 is a plan view exemplarily showing the structure of an electrode 90 according to a preferred embodiment of the present invention.

[0117] Referring to FIG. 11, electrode 90 includes a sheet-shaped current collector 91 made of a conductive foil, an active material layer 92 formed on at least one surface of current collector 91, and a plain portion 93 on a long side end of current collector 91 where no active material is coated.

[0118] Preferably, the plain portion 93 may include a plurality of segment pieces 93a that are notched. The plurality of segment pieces 93a may form a plurality of groups, and the segment pieces 93a belonging to each group may have the same height (length in the Y direction) and / or width (length in the Z direction) and / or spacing pitch. The number of segment pieces 93a belonging to each group may be increased or decreased from that shown in the figure. The segment pieces 93a may be trapezoidal, but may be modified into a rectangle, a parallelogram, a semicircle, or a semi-ellipse. Preferably, the height of the segment pieces 93a may increase stepwise from the core side to the outer periphery side. Also, the core side plain portion 93' adjacent to the core side may not include a segment piece 93a, and the height of the core side plain portion 93' may be smaller than other plain portion areas.

[0119] In one embodiment of the present specification, the electrode 90 may include an insulating coating layer 94 covering the boundary between the active material layer 92 and the uncoated portion 93. The insulating coating layer 94 includes an insulating polymer resin, and may optionally further include an inorganic filler. The insulating coating layer 94 prevents an end of the active material layer 92 from contacting an active material layer of the opposite polarity facing the active material layer 92 via a separator, and serves to structurally support the folding of the segment pieces 93a. For this reason, when the electrode 90 is wound into an electrode assembly, it is preferable that at least a portion of the insulating coating layer 94 is exposed to the outside from the separator.

[0120] FIG. 12 is a cross-sectional view taken along the longitudinal direction (Y) of an electrode assembly 100 in which the segmented structure of the uncoated portion of the electrode 90 according to an embodiment of the present invention is applied to a first electrode and a second electrode.

[0121] 12, the electrode assembly 100 may be manufactured by the winding method described in FIG. 2. For ease of explanation, the protruding structure of the uncoated portions 72, 73 extending outward from the separator is shown in detail, and the winding structure of the first electrode, the second electrode, and the separator is not shown. The uncoated portion 72 protruding downward extends from the first electrode, and the uncoated portion 73 protruding upward extends from the second electrode. The pattern in which the heights of the uncoated portions 72, 73 vary is shown diagrammatically.

[0122] That is, the height of the uncoated portions 72, 73 may vary irregularly depending on where the cross section is cut. As an example, when a side portion of the trapezoidal segment piece 93a is cut, the height of the uncoated portion in the cross section will be lower than the height of the segment piece 93a. Therefore, it should be understood that the height of the uncoated portions 72, 73 shown in the drawings showing the cross section of the electrode assembly 100 corresponds to the average height of the uncoated portions included in each winding turn.

[0123] The uncoated portions 72 and 73 may be folded from the outer periphery of the electrode assembly 100 to the core as shown in FIG. 12. In FIG. 12, the folded portion 101 is indicated by a dotted box. When the uncoated portions 72 and 73 are folded, the radially adjacent segments overlap each other multiple times, forming folded surfaces 102 at the upper and lower parts of the electrode assembly 100. At this time, the core-side uncoated portion (93' in FIG. 11) is not folded due to its low height, and the height (h) of the segment folded at the innermost side is equal to or smaller than the radial length (r) of the winding region formed by the core-side uncoated portion 93' without a segment structure. Therefore, the cavity 80 in the core of the electrode assembly 100 is not closed by the folded segments. If the cavity 80 is not closed, the electrolyte injection process is not difficult and the electrolyte injection efficiency is improved.

[0124] In the secondary battery 70 according to the embodiment of the present invention, the cap plate 74a of the sealing body 74 does not have polarity. Instead, the second current collector plate 78 is connected to the side wall of the battery can 51, and the outer surface 52a of the bottom 52 of the battery can 51 has the opposite polarity to the electrode terminal 50. Therefore, when connecting a plurality of cells in series and / or in parallel, wiring such as a bus bar connection can be performed on the upper part of the secondary battery 70 using the outer surface 52a of the bottom 52 of the battery can 51 and the electrode terminal 50. This can increase the number of cells that can be mounted in the same space, thereby improving the energy density.

[0125] In one embodiment of the present specification, the secondary battery may include an electrode terminal riveted to the bottom of the battery can.

[0126] FIG. 5 is a cross-sectional view showing the riveting structure of an electrode terminal 50 according to an embodiment of the present invention, and FIG. 6 is an enlarged cross-sectional view of the part circled by a dotted line.

[0127] 5 and 6, the riveting structure of the electrode terminal 50 according to the embodiment may include a cylindrical battery can 51 having one side open, an electrode terminal 50 riveted through a through hole 53 formed in a bottom 52 of the battery can 51, and a rivet gasket 54 interposed between the electrode terminal 50 and the through hole 53.

[0128] The battery can 51 is made of a conductive metal material. In one example, the battery can 51 may be made of a steel material, but the present invention is not limited thereto.

[0129] The electrode terminal 50 is made of a conductive metal material. In one example, the electrode terminal 50 may be made of aluminum, but the present invention is not limited thereto.

[0130] In one embodiment of the present specification, the rivet gasket 54 may be made of insulating and elastic polymer resin. In one example, the rivet gasket 54 may be made of polypropylene, polybutylene terephthalate, polyethylene fluoride, etc., but the present invention is not limited thereto.

[0131] In one embodiment of the present specification, the electrode terminal 50 may include a body portion 50a inserted into the through-hole 53, an external flange portion 50b extending from one side of the body portion 50a exposed through the external surface 52a of the bottom 52 of the battery can 51 along the external surface 52a, an internal flange portion 50c extending from the other side of the body portion 50a exposed through the internal surface 52b of the bottom 52 of the battery can 51 toward the internal surface 52b, and a flat portion 50d provided on the inside of the internal flange portion 50c.

[0132] Preferably, the flat portion 50d and the inner surface 52b of the bottom 52 of the battery can 51 may be parallel to each other. Here, "parallel" means that they are substantially parallel when observed with the naked eye.

[0133] According to one aspect, the angle (θ) between the inner flange portion 50c and the inner surface 52b of the bottom 52 of the battery can 51 may be from 0 degrees to 60 degrees. The size of the angle is determined by the crimping strength when the electrode terminal 50 is installed in the through hole 53 of the battery can 51 by a crimping method. In one example, the angle (θ) may be reduced to 0 degrees as the crimping strength increases. If the angle exceeds 60 degrees, the sealing effect of the rivet gasket 54 may be reduced.

[0134] In one embodiment of the present specification, a recess 55 may be provided between the inner flange portion 50c and the flat portion 50d. The recess 55 may have an asymmetric groove cross-sectional structure. In one example, the asymmetric groove may be substantially V-shaped. The asymmetric groove may include a side wall 55a of the flat portion 50d and an inclined surface 55b of the inner flange portion 50c that is connected to an end of the side wall 55a. The side wall 55a may be substantially perpendicular to the inner surface 52b of the bottom 52 of the battery can 51. "Perpendicular" means that it is substantially perpendicular when observed visually. The recess 55 is formed according to the shape of a crimping jig when the electrode terminal 50 is provided in the through hole 53 of the battery can 51 by a crimping method. Preferably, the thickness of the inner flange portion 50c may decrease as it gets farther from the body portion 50a of the electrode terminal 50.

[0135] In one embodiment of the present specification, the rivet gasket 54 can include an external gasket 54a interposed between the external flange portion 50b and the external surface 52a of the bottom 52 of the battery can 51, and an internal gasket 54b interposed between the internal flange portion 50c and the internal surface 52b of the bottom 52 of the battery can 51.

[0136] The outer gasket 54a and the inner gasket 54b may have different thicknesses depending on the position. Preferably, the thickness of the inner gasket 54b may be relatively small in a region between the inner edge 56 of the through hole 53 connected to the inner surface 52b of the bottom 52 of the battery can 51 and the inner flange portion 50c. Preferably, a minimum thickness point may be present in the gasket region between the inner edge 56 of the through hole 53 and the inner flange portion 50c. In addition, the inner edge 56 of the through hole 53 may include an opposing surface 57 facing the inner flange portion 50c.

[0137] Meanwhile, the upper and lower ends of the inner wall of the through hole 53 perpendicular to the bottom 52 of the battery can 51 are chamfered to form a tapered surface toward the electrode terminal 50. However, the upper and / or lower ends of the inner wall of the through hole 53 may be deformed into a smooth curved surface having a curvature. In this case, the stress applied to the gasket 54 near the upper and / or lower ends of the inner wall of the through hole 53 can be further alleviated.

[0138] Preferably, the internal gasket 54b can extend longer than the internal flange portion 50c while forming an angle of 0 to 60 degrees with the internal surface 52b of the bottom 52 of the battery can 51.

[0139] In another aspect, the height (H1) of the flat portion 50d with respect to the inner surface 52b of the bottom 52 of the battery can 51 may be equal to or greater than the height (H2) of the end of the inner gasket 54b.

[0140] Furthermore, the height (H1) of the flat portion 50d may be equal to or greater than the height (H3) of the end of the internal flange portion 50c based on the internal surface 52b of the bottom 52 of the battery can 51. If the height parameters H1, H2, and H3 satisfy the above conditions, the internal flange portion 50c and the internal gasket 54b can be prevented from interfering with other components.

[0141] In one embodiment of the present specification, the radius (R1) from the center of the body portion 50a of the electrode terminal 50 to the edge of the external flange portion 50b may be 10 to 60% of the radius (R2) of the bottom 52 of the battery can 51.

[0142] If R1 is small, there will be insufficient welding space when welding an electric wiring component (bus bar) to the electrode terminal 50. Also, if R1 is large, there will be less welding space when welding an electric wiring component (bus bar) to the outer surface 52a of the bottom 52 of the battery can 51 excluding the electrode terminal 50. By adjusting the ratio R1 / R2 between 10% and 60%, it is possible to appropriately ensure the welding space for the electrode terminal 50 and the outer surface of the bottom 52 of the battery can 51.

[0143] In one embodiment of the present specification, the radius (R3) from the center of the body 50a of the electrode terminal 50 to the edge of the flat portion 50d may be 4 to 30% based on the radius (R2) of the bottom 52 of the battery can 51. If R3 is small, there may be insufficient welding space when welding a current collector plate (see 79 in FIG. 7) to the flat portion 50d of the electrode terminal 50, and the welding area of ​​the electrode terminal 50 may decrease, resulting in an increase in contact resistance. In addition, R3 must be smaller than R1. If R3 is large, the thickness of the inner flange portion 50c may become thin, weakening the force with which the inner flange portion 50c presses the rivet gasket 54, which may result in a decrease in the sealing ability of the rivet gasket 54.

[0144] By adjusting R3 / R2 between 4 and 30%, a sufficient welding area can be secured between the flat portion 50d of the electrode terminal 50 and the current collecting plate (79 in FIG. 7), which not only facilitates the welding process but also reduces the contact resistance in the welding area and prevents a decrease in the sealing ability of the rivet gasket 54.

[0145] According to an embodiment of the present specification, the flat portion of the electrode terminal and the current collecting plate may be electrically connected. Specifically, the current collecting plate and the flat portion may be directly connected through a welding process or may be electrically connected using an electrode tab, lead, etc. In this case, the welding process is not limited as long as it is a method commonly used in the art.

[0146] According to an embodiment of the present invention, the riveting structure of the electrode terminal 50 can be formed using a crimping tool that moves up and down. First, a preform (not shown) of the electrode terminal 50 is inserted into a through hole 53 formed in a bottom 52 of a battery can 51 with a rivet gasket 54 interposed therebetween. The preform refers to the electrode terminal before being riveted.

[0147] Next, a crimping jig is inserted into the inner space of the battery can 51. The crimping jig has grooves and protrusions corresponding to the final shape of the electrode terminal 50 on the surface facing the preform, in order to form the electrode terminal 50 by riveting the preform.

[0148] Next, the crimping tool is moved downward to pressure-form the upper part of the preform, thereby transforming the preform into a riveted electrode terminal 50.

[0149] While the preform is pressurized by the crimping tool, the outer gasket 54a interposed between the outer flange portion 50b and the outer surface 52a of the bottom 52 of the battery can 51 is elastically compressed and its thickness is reduced. Also, the portion of the inner gasket 54b interposed between the inner edge 56 of the through hole 53 and the preform is elastically compressed by the inner flange portion 50c and its thickness is reduced more than other regions. In particular, the region where the thickness of the inner gasket 54b is reduced intensively is the portion indicated by the dotted circle in FIG. 6. As a result, the sealing and hermeticity between the riveted electrode terminal 50 and the battery can 51 is significantly improved.

[0150] Preferably, the rivet gasket 54 is compressed sufficiently to ensure the desired sealing strength without being physically damaged during the riveting process of the preform.

[0151] In one example, when the rivet gasket 54 is made of polybutylene terephthalate, the rivet gasket 54 preferably has a compressibility of 50% or more at the point where it is compressed to its minimum thickness. Compressibility is the ratio of thickness change before and after compression to the thickness before compression. In another example, when the rivet gasket 54 is made of polyfluoroethylene, the rivet gasket 54 preferably has a compressibility of 60% or more at the point where it is compressed to its minimum thickness.

[0152] In yet another example, when the rivet gasket 54 is made of polypropylene, it is preferred that the rivet gasket 54 have a compressibility of 60% or greater at the point where it is compressed to its minimum thickness.

[0153] Preferably, the crimping jig is moved up and down at least twice to perform the pressure forming of the upper part of the preform in stages. That is, the preform can be deformed several times by pressure forming in stages. At this time, the pressure applied to the crimping jig can be increased in stages. In this way, the stress applied to the preform can be dispersed several times, thereby preventing the rivet gasket 54 from being damaged during the crimping process. In particular, when the portion of the internal gasket 54b interposed between the inner edge 56 of the through hole 53 and the preform is compressed intensively by the internal flange portion 50c, damage to the gasket is minimized.

[0154] After the pressure forming of the preform using the crimping jig is completed, the crimping jig is separated from the battery can 51, whereby the riveted structure of the electrode terminal 50 according to the embodiment of the present invention can be obtained as shown in FIG.

[0155] According to the above-described embodiment, the crimping jig pressurizes and forms the upper part of the preform by moving up and down inside the battery can 51. In some cases, a rotary jig used in the prior art may be used to pressurize the preform.

[0156] However, the rotary rotation jig rotates while being tilted at a certain angle with respect to the central axis of the battery can 51. Therefore, a rotary rotation jig with a large radius of rotation may interfere with the inner wall of the battery can 51. Furthermore, if the battery can 51 is deep, the length of the rotary rotation jig will also be long accordingly. In this case, the radius of rotation of the end of the rotary rotation jig becomes large, and pressure forming of the preform may not be performed properly.

[0157] Therefore, pressure forming using a crimping jig is more effective than the method using a rotary rotating jig.

[0158] The riveting structure of the electrode terminal 50 according to the embodiment of the present invention described above is applicable to cylindrical secondary batteries.

[0159] In one embodiment of the present specification, the secondary battery may be a cylindrical secondary battery having a form factor ratio (defined as the value obtained by dividing the diameter by the height of a cylindrical battery, i.e., the ratio of the diameter (Φ) to the height (H)) of greater than 0.4. Here, the form factor refers to values ​​indicating the diameter and height of a cylindrical secondary battery.

[0160] Conventionally, batteries with a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 18650 cells, 21700 cells, etc. have been used. In the case of an 18650 cell, its diameter is about 18 mm, its height is about 65 mm, and its form factor ratio is about 0.277. In the case of a 21700 cell, its diameter is about 21 mm, its height is about 70 mm, and its form factor ratio is about 0.300.

[0161] The cylindrical secondary battery according to an embodiment of the present specification may be a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 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.

[0162] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 46 mm, a height of 110 mm, and a form factor ratio of 0.418.

[0163] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 48 mm, a height of 75 mm, and a form factor ratio of 0.640.

[0164] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 48 mm, a height of 110 mm, and a form factor ratio of 0.436.

[0165] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 48 mm, a height of 80 mm, and a form factor ratio of 0.600.

[0166] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 46 mm, a height of 80 mm, and a form factor ratio of 0.575.

[0167] The present specification provides a current collector for a secondary battery including an electrode assembly formed by stacking and winding a first electrode, a separator, and a second electrode, the first electrode including a first electrode collector and an electrode active material layer provided on the first electrode collector, the long side end of the first electrode collector along the winding direction including an uncoated portion of the first electrode not provided with the electrode active material layer, a battery can containing the electrode assembly and including an opening, a cap plate configured to seal the opening of the battery can, and an electrode terminal riveted to the battery can, the current collector being provided at one end of the electrode assembly where the uncoated portion of the first electrode is exposed, including a central portion corresponding to the winding core of the electrode assembly, the central portion including a first welded portion having a thickness thinner than the remaining thickness of the current collector. The components of the current collector are as described above.

[0168] The secondary battery according to an embodiment of the present specification can be used to manufacture a battery pack. Fig. 14 is a diagram showing a schematic configuration of a battery pack according to an embodiment of the present invention.

[0169] 14, a battery pack 200 according to an embodiment of the present invention includes an assembly in which secondary battery cells 201 are electrically connected, and a pack housing 202 that accommodates the assembly. The cylindrical secondary battery cells 201 are the battery cells according to the above-mentioned embodiment. For convenience of illustration, components such as a bus bar for electrically connecting the cylindrical secondary battery cells 201, a cooling unit, and external terminals are omitted in the drawings.

[0170] The battery pack 200 can be mounted on an automobile. The automobile may be, for example, an electric automobile, a hybrid automobile, or a plug-in hybrid automobile. The automobile includes a four-wheeled automobile or a two-wheeled automobile. FIG. 15 is a diagram for explaining an automobile including the battery pack 200 of FIG. 14.

[0171] 15, an automobile V according to an embodiment of the present specification includes a battery pack 200 according to an embodiment of the present specification. The automobile V is operated by receiving power from the battery pack 200 according to an embodiment of the present invention.

[0172] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is of course possible for a person having ordinary knowledge in the technical field to which the present invention pertains to make various modifications and variations within the technical spirit of the present invention and the equivalent scope of the following claims.

Claims

1. An electrode assembly in which a first electrode, a second electrode, and a separator provided therebetween are wound up, the first electrode and the second electrode each including a non-coated portion at a long side end portion thereof that is not coated with an active material and is exposed to the outside of the separator; and a current collector provided at one end of the electrode assembly where an uncoated portion of the first electrode is exposed, the current collector including a central portion corresponding to a winding core of the electrode assembly and a peripheral portion provided around the central portion and in contact with the one end of the electrode assembly; the peripheral portion includes one or more first through holes provided so that at least a portion of the uncoated portion of the first electrode passes through the first through holes, a non-coated portion of the first electrode exposed to the outside through the first through-hole of the current collector plate is bent one or more times so as to contact an upper portion of the current collector plate.

2. The secondary battery of claim 1 , wherein the central portion of the current collector further includes a central hole provided in a portion corresponding to a winding core of the electrode assembly.

3. An electrode assembly in which a first electrode, a second electrode, and a separator provided between them are wound up, the first electrode and the second electrode each having a long side end portion that is not coated with an active material and includes a plain portion exposed to the outside of the separator; and a current collector provided at one end of the electrode assembly where an uncoated portion of the first electrode is exposed, the current collector including a central portion corresponding to a winding core of the electrode assembly and a peripheral portion provided around the central portion and in contact with the one end of the electrode assembly; the peripheral portion includes one or more first through holes provided so that at least a portion of the uncoated portion of the first electrode passes through the first through holes, a non-coated portion of the first electrode exposed to the outside through the first through hole of the current collector plate is folded one or more times in a winding core direction of the electrode assembly.

4. The secondary battery according to claim 1 , wherein the peripheral portion of the current collector plate includes two or more first through holes spaced apart in a winding direction of the electrode assembly.

5. The secondary battery according to claim 1 , wherein the peripheral portion of the current collector plate includes one or more first through hole groups including two or more first through holes spaced apart from the center toward any one of the outer periphery directions.

6. The secondary battery according to claim 5 , wherein the first through-hole group includes two to six first through-holes spaced apart from the center toward any one of the outer peripheries.

7. 6. The secondary battery according to claim 5, wherein the peripheral portion of the current collector plate includes two to six of the first through hole groups, and each of the first through hole groups is spaced apart from each other in the winding direction of the electrode assembly.

8. 6. The secondary battery according to claim 5, wherein the peripheral portion of the current collector plate includes two of the first through hole groups, the two first through hole groups being arranged to face each other across the center portion.

9. An electrode assembly in which a first electrode, a second electrode, and a separator provided between them are wound up, the first electrode and the second electrode each having a long side end portion that is not coated with an active material and includes a plain portion exposed to the outside of the separator; and a current collector provided at one end of the electrode assembly where an uncoated portion of the first electrode is exposed, the current collector including a central portion corresponding to a winding core of the electrode assembly and a peripheral portion provided around the central portion and in contact with the one end of the electrode assembly; the peripheral portion includes one or more first through holes provided so that at least a portion of the uncoated portion of the first electrode passes through the first through holes, The peripheral portion of the current collector plate includes one or more first through hole groups including two or more first through holes spaced apart from the center toward any one of the outer periphery directions, A secondary battery, wherein a peripheral portion of the current collector plate includes three to six of the first through hole groups, and each of the first through hole groups is arranged spaced apart from each other in the winding direction of the electrode assembly.

10. An electrode assembly in which a first electrode, a second electrode and a separator provided between them are wound up, the first electrode and the second electrode each having a long side end portion that is not coated with an active material and includes a plain portion exposed to the outside of the separator; and a current collector provided at one end of the electrode assembly where an uncoated portion of the first electrode is exposed, the current collector including a central portion corresponding to a winding core of the electrode assembly and a peripheral portion provided around the central portion and in contact with the one end of the electrode assembly; the peripheral portion includes one or more first through holes provided so that at least a portion of the uncoated portion of the first electrode passes through the first through holes, At least one of the first through holes is provided in contact with an edge of the current collector plate.

11. The secondary battery according to claim 1 , wherein the first through-holes are slit-shaped or dot-shaped.

12. The secondary battery according to claim 1 , wherein the peripheral portion of the current collector plate further includes one or more second through holes.

13. The peripheral portion of the current collector plate includes two or more first through hole groups, The peripheral portion of the current collector further includes one or more second through holes, The secondary battery according to claim 5 , wherein the second through-hole is provided between two adjacent groups of the first through-holes.

14. The secondary battery according to claim 1 , wherein the current collector plate further includes an electrode tab.

15. A battery pack comprising a plurality of the secondary batteries according to any one of claims 1 to 14.

16. A motor vehicle comprising at least one battery pack according to claim 15.

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