Secondary battery

Abstract

The present invention relates to a secondary battery in which, because the top surface and the bottom surface of an electrode assembly have surface roughness, protrusions with increased surface roughness are provided on surfaces of a current collecting plate in contact with the top surface and the bottom surface of the electrode assembly, thereby enhancing contact force and thus reducing contact resistance. For example, disclosed is a secondary battery comprising: an electrode assembly including a first electrode plate, a separator, and a second electrode plate; a case accommodating the electrode assembly; a terminal passing through the case; and a first current collecting plate disposed between the top surface of the electrode assembly and the case and electrically connecting the first electrode plate to the terminal, wherein the first current collecting plate includes: a bottom surface in contact with the top surface of the electrode assembly; and a top surface opposite to the bottom surface. The bottom surface of the first current collecting plate includes protrusions protruding toward the electrode assembly, and the surface roughness of the protrusions is greater than the surface roughness of the top surface of the first current collecting plate.

Description

secondary battery

[0001] The present disclosure relates to a secondary battery.

[0002] Secondary batteries are power storage systems that offer superior energy density by converting electrical energy into chemical energy and storing it. Compared to non-rechargeable primary batteries, secondary batteries are rechargeable and are widely used in IT devices such as smartphones, cellphones, laptops, and tablet PCs. Recently, interest in electric vehicles has grown to prevent environmental pollution, leading to the adoption of high-capacity secondary batteries in electric vehicles. These secondary batteries require high density, high output, and stability.

[0003] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present invention, and therefore may include information that does not constitute prior art.

[0004] In the present invention, since the upper and lower surfaces of the electrode assembly have surface roughness, a protrusion with increased surface roughness is provided on the surface of the current collector plate that comes into contact with the upper and lower surfaces of the electrode assembly, thereby improving contact force and reducing contact resistance.

[0005] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0006] According to one embodiment of the present invention for solving the above technical problem, a secondary battery includes an electrode assembly having a first electrode plate, a separator, and a second electrode plate, a case in which the electrode assembly is accommodated, a terminal penetrating the case, and a first collector plate interposed between an upper surface of the electrode assembly and the case and electrically connecting the first electrode plate and the terminal, wherein the first collector plate includes a lower surface in contact with the upper surface of the electrode assembly and an upper surface opposite to the lower surface, and the lower surface of the first collector plate has a protrusion protruding in the direction of the electrode assembly, and a surface roughness of the protrusion may be greater than a surface roughness of the upper surface of the first collector plate.

[0007] The first collector plate may include a terminal connection portion in a circular plate shape that contacts and is electrically connected to the lower surface of the terminal, and a plate connection portion that contacts and is electrically connected to the first electrode tab exposed to the upper surface of the electrode assembly and is located on the outside of the terminal connection portion.

[0008] The above electrode plate connecting portion extends in the diametric direction, has a welding area welded to the upper surface of the electrode assembly, and has a protrusion provided in an area other than the welding area, and at least two of the protrusions may be provided in the diametric direction of the electrode plate connecting portion.

[0009] The upper surface of the above-mentioned plate connection part may be a flat plane.

[0010] The upper surface of the above-mentioned plate connection part may be provided with a concave portion corresponding to the above-mentioned protrusion.

[0011] The lower surface of the above-mentioned electrode plate connection part is roughened, so that the surface roughness may be greater than that of the upper surface of the above-mentioned electrode plate connection part.

[0012] The height of the above-mentioned protrusion may be equal to or lower than the height of the winding end protrusion that comes into contact with the winding end region of the electrode assembly and the height of the winding end protrusion that comes into contact with the winding end of the electrode assembly, which is located in the middle region other than the above-mentioned region.

[0013] The first electrode plate further includes a plurality of first electrode tabs that protrude upward from the upper surface of the electrode assembly and are bent and pressed in the winding axis direction of the electrode assembly,

[0014] The second electrode plate may further include a plurality of second electrode tabs that protrude downward from the lower surface of the electrode assembly and are bent and pressed in the direction of the winding axis of the electrode assembly.

[0015] The above electrode assembly may have a cumulative thickness, which is a height at which the first electrode tab is bent and compacted, that is, a central region higher than the winding leading edge and winding ending.

[0016] The electrode assembly may further include a second collector plate in the shape of a circular plate corresponding to the lower surface of the electrode assembly, and in contact with and electrically connected to the second electrode tab exposed to the lower surface of the electrode assembly.

[0017] The second collector plate has a circular flat surface in contact with the lower surface of the electrode assembly; and

[0018] It may include an extension extending downward from the edge of the above-mentioned flat portion and contacting the case.

[0019] The above-mentioned flat portion includes a plurality of protrusions protruding toward the lower surface of the electrode assembly on the upper surface of the second collector plate, and the surface roughness of the protrusions may be greater than the surface roughness of the lower surface of the second collector plate.

[0020] The surface roughness of the upper surface of the second collector plate may be greater than the surface roughness of the lower surface of the second collector plate.

[0021] The case includes an upper portion; and a body portion extending downward from an edge of the upper portion, wherein the terminal penetrates the upper portion of the case and can be coupled to the first collector plate.

[0022] The above case may further include a cap plate that seals the lower end of the body portion.

[0023] The case may further include a lower portion; and a body portion extending upward from an edge of the lower portion, and a cap plate sealing an upper end of the body portion.

[0024] The terminal can be coupled to the first collector plate by penetrating the cap plate.

[0025] The surface roughness of the lower surface of the above electrode assembly may be greater than the surface roughness of the upper surface.

[0026] The plurality of first electrode tabs may be arranged in a plurality of places spaced apart from each other along the winding direction, in the first bare portion where no electrode active material is applied on the first electrode plate.

[0027] The above plurality of first electrode tabs may not be provided at the winding tip and winding end of the first electrode plate.

[0028] According to the present invention, since the upper and lower surfaces of the electrode assembly have surface roughness, a protrusion having a high surface roughness is provided on the surface of the current collector plate that comes into contact with the upper and lower surfaces of the electrode assembly, thereby improving contact force and thereby reducing contact resistance, a secondary battery can be provided.

[0029] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0030] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0031] Figure 1 is a perspective view illustrating a secondary battery according to the present invention.

[0032] Figure 2 is a cross-sectional view of the secondary battery illustrated in Figure 1.

[0033] Figure 3 is a perspective view illustrating an electrode assembly in the secondary battery of Figure 1.

[0034] Figure 4 is a cross-sectional view of the electrode assembly of Figure 3.

[0035] Figure 5 is an exploded perspective view of the secondary battery of Figure 1, with the electrode assembly and the collector plate disassembled.

[0036] Fig. 6 is a cross-sectional view of the electrode assembly and the collector plate combined in Fig. 5.

[0037] Figure 7 is a plan view showing four areas randomly selected from the upper and lower surfaces of the electrode assembly in Figure 5.

[0038] Figure 8 is a bottom view of the first collector plate of the secondary battery illustrated in Figure 1.

[0039] Figures 9 to 12 are various examples of cross-sectional views taken along line A-A' in the first collector plate of the secondary battery of Figure 8.

[0040] FIGS. 13 to 16 are plan views illustrating various examples of the first collector plate in the secondary batteries illustrated in FIGS. 1 to 6.

[0041] Figure 17 is a cross-sectional view illustrating a secondary battery according to the present invention.

[0042] FIGS. 18A and 18B are perspective views illustrating a battery pack including an exemplary secondary battery according to the present invention.

[0043] FIGS. 19A and 19B are perspective and side views illustrating a vehicle including an exemplary battery pack according to the present invention.

[0044] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0045] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0046] Additionally, to facilitate understanding of the invention, the attached drawings may not be drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0047] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0048] Although the terms "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used solely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0049] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0050] Any configuration being placed "on (or under)" or "above (or below)" a component may mean not only that any configuration is placed in contact with the upper surface (or lower surface) of said component, but also that other configurations may intervene between said component and any configuration placed on (or below) said component.

[0051] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to each other, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component. Furthermore, when it is said that a part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where they are connected with another element in between.

[0052] When reference is made throughout the specification to "A and / or B," this means A, B, or A and B, unless otherwise stated. In other words, "and / or" includes all or any combination of the listed items. When reference is made to "C through D," this means C or more and D or less, unless otherwise stated.

[0053] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure.

[0054] FIG. 1 is a perspective view illustrating a secondary battery according to the present invention, and FIG. 2 is a cross-sectional view of the secondary battery illustrated in FIG. 1.

[0055] As illustrated in FIGS. 1 and 2, a secondary battery (100) according to the present invention may include an electrode assembly (110), a case (120) that accommodates the electrode assembly (110) and an electrolyte (optional) therein, and a terminal (150) coupled to a terminal hole (122a) provided at one end of the case (120), for example, an upper end. In addition, the secondary battery (100) may include a cap plate (160) that seals the other end of the case (110), for example, a lower end. Here, the cap plate (160) is coupled with the case (120) to accommodate the electrode assembly (110) therein, and thus may be viewed as a part of the case (120).

[0056] The secondary battery (100) may further include a first collector plate (130) that electrically connects the first electrode (111) of the electrode assembly (110) and the terminal (150) and a second collector plate (140) that electrically connects the second electrode (112) of the electrode assembly (110) and the case (120).

[0057] The electrode assembly (110) may include a separator (113), a first electrode plate (111) and a second electrode plate (112) positioned with the separator (113) between them, and may be wound in a jelly-roll shape.

[0058] The first electrode plate (111) may include a first substrate and a first active material layer positioned on the first substrate. A first electrode tab (111b) may extend outward from a first electrode non-conductive portion (111a) of the first substrate where the first active material layer is not positioned, and the first electrode tab (111b) may be electrically connected to a terminal (150) via a first current collector (130). The second electrode plate (112) may include a second substrate and a second active material layer positioned on the second substrate. A second electrode tab (112b) may extend outward from a second electrode non-conductive portion (112a) of the second substrate where the second active material layer is not positioned, and the second electrode tab (112b) may be electrically connected to a case (120) via a second current collector (140).

[0059] The first electrode tab (111b) and the second electrode tab (112b) may be positioned in opposite directions in the electrode assembly (110). The first electrode plate (111) may function as an anode. In this case, the first substrate may be composed of, for example, aluminum foil, and the first active material layer may include, for example, a transition metal oxide. The second electrode plate (112) may function as an anode. In this case, the second substrate may be composed of, for example, copper foil or nickel foil, and the second active material layer may include, for example, graphite.

[0060] The separator (113) functions to prevent short circuiting between the first electrode (111) and the second electrode (112) while allowing the movement of lithium ions. The separator (113) may be composed of, for example, a polyethylene film, a polypropylene film, a polyethylene-polypropylene film, etc.

[0061] In some examples, a compound capable of reversible intercalation and deintercalation of lithium (a lithiated intercalation compound) may be used as the cathode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from the group consisting of cobalt, manganese, nickel, and combinations thereof may be used.

[0062] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0063] As an example, a compound represented by any one of the following chemical formulas may be used. LiaA1-bXbO2-cDc(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaMn2-bXbO4-cDc(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaNi1-b-cCobXcO2-αDα(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); LiaNi1-b-cMnbXcO2-αDα(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); LiaNibCocL1dGeO2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); LiaNiGbO2(0.90≤a≤1.8, 0.001≤b≤0.1); LiaCoGbO2(0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn1-bGbO2 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn2GbO4 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn1-gGgPO4(0.90≤a≤1.8, 0≤g≤0.5); Li(3-f)Fe2(PO4)3(0≤f≤2); LiaFePO4(0.90≤a≤1.8).

[0064] In the chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L1 is Mn, Al, or a combination thereof.

[0065] A positive electrode for a lithium secondary battery may include a current collector (e.g., a first substrate) and a positive electrode active material layer formed on the current collector. The positive electrode active material layer includes a positive electrode active material and may further include a binder and / or a conductive material.

[0066] The content of the positive electrode active material may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive electrode active material layer, and the contents of the binder and conductive material may be 0.5 wt% to 5 wt%, respectively, with respect to 100 wt% of the positive electrode active material layer.

[0067] Aluminum may be used as the current collector, but is not limited thereto.

[0068] The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0069] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0070] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. The Si-based negative electrode active material can be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-based alloy, or a combination thereof.

[0071] The above silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles.

[0072] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0073] A negative electrode for a lithium secondary battery may include a current collector (e.g., a second substrate) and a negative electrode active material layer formed on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material.

[0074] For example, the negative electrode active material layer may include 90 to 99 wt% of the negative electrode active material, 0.5 to 5 wt% of the binder, and 0 to 5 wt% of the conductive material.

[0075] The above binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof. When an aqueous binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included.

[0076] The current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0077] An electrolyte for a lithium secondary battery may include a non-aqueous organic solvent and a lithium salt.

[0078] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0079] The above non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof, and may be used alone or in combination of two or more thereof.

[0080] Additionally, when using a carbonate solvent, a mixture of cyclic carbonate and chain carbonate can be used.

[0081] As described above, a lithium secondary battery may have a separator between the positive and negative electrodes. Such a separator may be a multilayer film of polyethylene, polypropylene, polyvinylidene fluoride, or two or more layers thereof.

[0082] The above separator may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof, positioned on one or both sides of the porous substrate.

[0083] The above organic material may include a polyvinylidene fluoride-based antibody or a (meth)acrylic polymer.

[0084] The above inorganic material may include inorganic particles selected from, but not limited to, Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0085] The organic and inorganic substances may be mixed and present in one coating layer, or a coating layer including an organic substance and a coating layer including an inorganic substance may be present in a laminated form.

[0086] The case (120) accommodates the electrode assembly (110) and the electrolyte, and together with the terminal (150) and the cap plate (160), can form the outer shape of the secondary battery (100). The case (120) can include a body portion (121) having a roughly cylindrical shape, and an upper portion (122) connected to one side of the body portion (121). That is, the body portion (121) can extend downward from an edge of the upper portion (122). A beading portion (123) deformed toward the inside can be positioned in the body portion (121), and a crimping portion (124) bent toward the inside can be positioned at an end on the opening side of the body portion (121). A terminal hole (122a) passing through the center can be provided in the upper portion (122). The upper part (122) can be connected by inserting a terminal (150) into a terminal hole (122a). A terminal gasket (125) for sealing and electrical insulation may be further interposed between the terminal hole (122a) and the terminal (150).

[0087] The beading portion (123) can prevent the electrode assembly (110) from moving inside the case (120) and can facilitate the fixing of the cap gasket (127) and the cap plate (160). The crimping portion (124) can firmly fix the cap plate (160) by pressing the edge of the cap plate (160) through the cap gasket (127). The case (123) can be made of, for example, nickel-plated iron, aluminum, an aluminum alloy, or stainless steel.

[0088] The first collector plate (130) may have one surface (e.g., the lower surface) that is in contact with and coupled to the first electrode tab (111b) of the electrode assembly (110), and the other surface (e.g., the upper surface) opposite the one surface may be in contact with and coupled to the terminal (150). The first collector plate (130) may be welded to and electrically connected to the first electrode tab (111b) of the electrode assembly (110). The first collector plate (130) may be welded and electrically connected while the other surface is in contact with the terminal (150). The first collector plate (130) may further include a protrusion (139) protruding in the direction of the electrode assembly (110) on one surface.

[0089] The second collector plate (140) may generally have a central portion (141) that contacts and is coupled with the second electrode tab (112b) of the electrode assembly (110), and an edge portion (142) that contacts and is coupled with the body portion (121) of the case (120). The second collector plate (140) may be electrically connected by welding the central portion (141) to the second electrode tab (112b) of the electrode assembly (110). The second collector plate (140) may be electrically connected by welding the edge portion (142) in a state in which it contacts the beading portion (123) of the case (120). The second collector plate (140) may further include a protrusion (149) that protrudes in the direction of the electrode assembly (110) at the central portion (141).

[0090] The terminal (150) may include a head (151) positioned on the outside of the case (120), and a fastening portion (152) extending inwardly from the center of the head (151) toward the inside of the case (120). The terminal (150) may be fixed and sealed by having the fastening portion (152) coupled to a terminal hole (122a) together with a terminal gasket (125) so as to pressurize the upper portion (122) of the case (120) from the inside through the terminal gasket (125). The terminal (150) may further be provided with a terminal groove (153) extending from the center of the head (151) toward the fastening portion (152). The terminal (150) may be welded to the first collector plate (130) from the outside through the terminal groove (153). The terminal (150) can be electrically connected to the first electrode (111) of the electrode assembly (110) through the first collector plate (130). The terminal (150) and the case (120) can have different polarities.

[0091] The cap plate (160) can be secured to the inside of the crimping portion (124) via the cap gasket (127) to seal the case (120). The cap plate (160) can include a safety vent (165) that is thinner than other areas due to a notch. When gas is generated due to overcharging or abnormal operation of the secondary battery (100), the safety vent (165) provided in the cap plate (160) can be cut along the notch. The cut safety vent (165) can prevent an explosion of the secondary battery (100) by releasing the gas to the outside.

[0092] Fig. 3 is a perspective view illustrating an electrode assembly in the secondary battery of Fig. 1, and Fig. 4 is a cross-sectional view of the electrode assembly of Fig. 3. In Figs. 3 and 4, the electrode assembly (110) is illustrated before the first electrode tab (111b) protruding upward and the second electrode tab (112b) protruding downward are bent.

[0093] In addition, FIG. 5 is a perspective view showing the electrode assembly (110) illustrated in FIG. 3 after the first electrode tab (111b) and the second electrode tab (112b) are bent toward the core. In addition, FIG. 5 is an exploded perspective view showing the electrode assembly (110) and the first collector plate (130) and the second collector plate (140) of the secondary battery of FIG. 1, in which they are exploded, and FIG. 6 is a cross-sectional view of FIG. 5.

[0094] Hereinafter, with reference to FIGS. 3 to 6, the structure and relationship of the electrode assembly (110), the first collector plate (130), and the second collector plate (140) will be described.

[0095] The first electrode plate (111) may be provided with a first electrode non-coated portion (111a) on the upper portion thereof, which is not coated with a first electrode active material. This first electrode non-coated portion (111a) may protrude upward from the electrode assembly (110). In addition, the first electrode non-coated portion (111a) may include a plurality of first electrode tabs (111b). The plurality of first electrode tabs (111b) may be positioned on the upper portion of the first electrode non-coated portion (111a) and may be arranged to be spaced apart from each other in one direction before winding. The plurality of first electrode tabs (111b) may not be provided at the winding leading end and / or the winding ending end. The plurality of first electrode tabs (111b) may be formed on the first electrode non-coated portion (111a) by laser notching, ultrasonic cutting, or punching. The above first electrode tab (111b) may protrude further upward than the second electrode plate (112) and separator (113) in the electrode assembly (110).

[0096] The second electrode plate (112) may be provided with a second electrode non-coated portion (112a) on the lower portion where the second electrode active material is not coated. In addition, the second electrode non-coated portion (112a) may include a plurality of second electrode tabs (112b). The plurality of second electrode tabs (112b) may be positioned on the lower portion of the second electrode non-coated portion (112a) and may be arranged to be spaced apart from each other in one direction before winding. The plurality of second electrode tabs (112b) may not be provided at the winding leading end and / or the winding ending end. The plurality of second electrode tabs (112b) may be formed on the second electrode non-coated portion (112a) by laser notching, ultrasonic cutting, or punching. A plurality of second electrode tabs (112b) like this may protrude further downward in the electrode assembly (110) compared to the first electrode plate (111) and the separator (113).

[0097] The electrode assembly (110) may have a first electrode tab (111b) that protrudes upward, and a second electrode tab (112b) that protrudes downward. The first electrode tab (111b) and the second electrode tab (112b) may be bent toward the core. That is, a plurality of first electrode tabs (111b) and a plurality of second electrode tabs (112b) may be bent and pressed from the winding end region toward the core. At this time, the first electrode tab (111b) and the second electrode tab (112b) may not be provided in some regions of the winding end so as not to cover the core hole (e.g., core) of the electrode assembly (110). The electrode assembly (110) may have surface roughness due to the step of the tabs on each of the upper surface (110a) and the lower surface (110b) by bending and compacting the first electrode tab (111b) and the second electrode tab (112b).

[0098] A first electrode tab (111b) may be positioned on the upper surface (110a) of the electrode assembly (110), and a second electrode tab (112b) may be positioned on the lower surface (110b). Fig. 7 shows four regions arbitrarily selected from the upper surface (110a) and the lower surface (110b) of the electrode assembly (110). Here, the four arbitrarily selected regions are shown as being symmetrical to each other with the core as the center, but any region may be selected as long as it has the same area. However, it is preferable that the four arbitrarily selected regions be regions that come into contact with the first collector plate (130) and the second collector plate (140). In addition, the four arbitrarily selected regions may be regions that are not welded to the first collector plate (130) and the second collector plate (140).

[0099] In addition, the surface roughness data, which is the result of the maximum height (Sz) and the average height (Sa) measured in the first region (a1), the second region (a2), the third region (a3), and the fourth region (a4) of the upper surface (110a) of the electrode assembly (110), and the maximum height (Sz) and the average height (Sa) measured in the first region (b1), the second region (b2), the third region (b3), and the fourth region (b4) of the lower surface (110b), may be as shown in Table 1 below. Here, the maximum height (Sz) is the height from the lowest point to the highest point (peak) within the area of ​​each region, and the average height (Sa) may be the average roughness in the area of ​​each region. The surface roughness may be measured through a contact-type or non-contact-type roughness measuring device.

[0100] Here, the surface roughness data for the upper surface (110a) and the lower surface (110b) of the electrode assembly (110) were measured for a total of three electrode assemblies (110), and Table 1 shows the experimental results for the first electrode assembly, Table 2 shows the experimental results for the second electrode assembly, and Table 3 shows the experimental results for the third electrode assembly. Here, the first electrode assembly, the second electrode assembly, and the third electrode assembly may be electrode assemblies having the same structure manufactured through the same process. Hereinafter, the unit may be μm.

[0101] Top surface (110a) SaSz Bottom surface (110b) SaSz First area (a1) 14.895 177.730 First area (b1) 39.596 191.190 Second area (a2) 14.140 127.890 Second area (b2) 20.413 154.590 Third area (a3) ​​12.433 123.550 Third area (b3) 35.470 164.840 Fourth area (a4) 14.658 281.420 Fourth area (b4) 38.03 1217.630 Average 14.03 177.648 Average 33.373 182.063 Standard deviation 0.96 363.583 Standard deviation 7.62 724.493

[0102] Top surface (110a) SaSz Bottom surface (110b) SaSz First area (a1) 13.076 128.230 First area (b1) 21.683 156.060 Second area (a2) 15.564 133.240 Second area (b2) 36.667 231.280 Third area (a3) ​​16.712 158.220 Third area (b3) 18.696 147.390 Fourth area (a4) 36.595 502.330 Fourth area (b4) 36.895 182.140 Average 19.97 1230.505 Average 24.485 179.218 Standard deviation 8.509 157.349 Standard deviation 8.363 32.666

[0103] Top surface (110a) SaSz Bottom surface (110b) SaSz First area (a1) 15.553165.060 First area (b1) 41.026214.340 Second area (a2) 18.525250.980 Second area (b2) 37.204211.560 Third area (a3) ​​13.827141.380 Third area (b3) 29.711156.110 Fourth area (a4) 24.906520.360 Fourth area (b4) 38.648236.500 Average 18.203269.445 Average 36.647204.628 Standard deviation 4.219150.496 Standard deviation 4.23129.632

[0104] Referring to the surface roughness data for the upper surface (110a) of the electrode assembly (110) in Tables 1 to 3, the average height (Sa) measured for each region may be 12 µm to 36 µm, and the maximum height (Sz) may be 123 µm to 520 µm. In addition, referring to the surface roughness data for the lower surface (110b) of the electrode assembly (110), the average height (Sa) measured for each region may be 18 µm to 41 µm, and the maximum height (Sz) may be 147 µm to 236 µm. Referring to the surface roughness data of the electrode assembly (110) in Tables 1 to 3, the upper surface (110a) and the lower surface (110b) of the electrode assembly (110) may have surface roughness due to uneven steps caused by the bending and compaction of the first electrode tab (111b) and the second electrode tab (112b). In addition, the surface roughness of the lower surface (110b) of the electrode assembly (110) may be greater than that of the upper surface (110a). When a flat first collector plate (130) comes into contact with the upper surface (110a) of the electrode assembly (110) having such surface roughness, lifting may occur due to the difference in roughness, and the electrical resistance may increase due to the low contact area. To prevent this, the contact area can be increased through a protrusion (139) protruding downward on the lower surface of the first collector plate (130) facing the upper surface (110a) of the electrode assembly (110). The protrusion (139) can contact and press the first electrode tab (111b) located on the upper surface (110a) of the electrode assembly (100).

[0105] In addition, when a flat second collector plate (140) comes into contact with the lower surface (110b) of the electrode assembly (110) having a surface roughness, lifting may occur due to the difference in roughness, and the electrical resistance may increase due to the low contact area. To prevent this, the contact area can be increased through a protrusion (149) protruding upward on the upper surface (140a) of the second collector plate (140) opposite the lower surface (110b) of the electrode assembly (110). The protrusion (149) can contact and press the second electrode tab (112b) located on the lower surface (110b) of the electrode assembly (100).

[0106] Referring to Fig. 8, it is a bottom view of the first collector plate (130) of the secondary battery (100) illustrated in Fig. 1. Fig. 9 is a cross-sectional view taken along line A-A' of Fig. 8. Hereinafter, the first collector plate (130) will be described with reference to Figs. 8 and 9.

[0107] First, the first collector plate (130) may be a circular metal plate having a shape corresponding to the upper surface (110a) of the electrode assembly (110). The planar size of the first collector plate (130) may be equal to or smaller than the size of the upper surface (110a) of the electrode assembly (110). The first collector plate (130) may be fixed and electrically connected to the first electrode tab (111b) of the electrode assembly (110) by welding while the lower surface (130b) is in contact with the upper surface (110a) of the electrode assembly (110). The first collector plate (130) may be fixed and electrically connected to the terminal (150) by welding while the upper surface (130a) is in contact with the lower surface of the terminal (150). The first collector plate (130) serves as a passage for current flow between the first electrode plate (111) of the electrode assembly (110) and the terminal (150).

[0108] The first collector plate (130) may include a terminal connection portion (131), a plate connection portion (132), and a fuse portion (135). The terminal connection portion (131) is located at the center of the first collector plate (130) and may be formed in a substantially circular shape. The lower surface of the fastening portion (152) of the terminal (150) may be welded to the upper surface of the terminal connection portion (131). The plate connection portion (132) is located on the outer side of the terminal connection portion (131) and may be in contact with and electrically connected to the first electrode tab (111b) of the electrode assembly (110). For example, the first electrode tab (111b) exposed to the upper surface (110a) of the electrode assembly (110) may be welded to the lower surface of the plate connection portion (132).

[0109] The fuse part (135) may be formed between the terminal connection part (131) and the plate connection part (132). The fuse part (135) may include a fuse hole (136) and a plate connection part (137). When a short circuit or overcurrent occurs in the secondary battery (100), the fuse part (135) may melt and cut the plate connection part (137) by the heat generated, thereby blocking the current flowing in the secondary battery (100).

[0110] The fuse hole (136) is formed in a roughly 'C' shape along a portion of the outer periphery of the terminal connection portion (131), so that both ends of the fuse hole (136) can face each other. The fuse hole (136) can separate the terminal connection portion (131) and the plate connection portion (132). That is, the terminal connection portion (131) and the plate connection portion (132) can be separated from each other by the fuse hole (136).

[0111] The plate connector (137) can connect the terminal connector (131) and the plate connector (132). When a short circuit or overcurrent occurs in the secondary battery (100), the plate connector (137) can melt and cut due to the generated heat to block the current, thereby improving safety.

[0112] The shape of the first collector plate (130) can be changed into various forms, for example, having a terminal connection portion (131), a polar plate connection portion (132), and a fuse portion (135).

[0113] The electrode plate connecting portion (132) may include a welding area (138) and a protrusion (139). The welding area (138) may be provided in a diametric direction outward from the center of the electrode plate connecting portion (132). Here, the welding area (138) may have a uniform width and divide the electrode plate connecting portion (132) into uniform areas. For example, although the number of welding areas (138) is illustrated as four, the number may be three or less, and the number of welding areas (138) is not limited here. Here, the welding area (138) may be an area welded to the upper surface (110a) of the electrode assembly (110) by welding.

[0114] Additionally, the plate connection portion (132) may be provided with a protrusion (139) on the lower surface (130b) of an area other than the welding area (138). That is, the protrusion (139) may not be provided on the lower surface of the welding area (138).

[0115] The electrode plate connection portion (132) of the first collector plate (130) may have an area where a protrusion (139) is formed on the lower surface (130b) and a welding area (138) that is welded to the upper surface (110a) of the electrode assembly (110) by welding.

[0116] The protrusion (139) may be provided to protrude downward from the lower surface (130b) of the first collector plate (130). A plurality of protrusions (139) may be provided on the lower surface (130b) of the first collector plate (130) so as to be spaced apart from each other. In FIG. 8, the protrusions (139) are illustrated in three rows in the diametric direction, but there may be at least two or more in the diametric direction. The protrusions (139) may be circular in plan view and may protrude in an approximately hemispherical shape. The diameter of the protrusions (139) in plan view may be approximately 1 mm to approximately 15 mm. In addition, the maximum height of the protrusions (139) may be approximately 0.4 mm to approximately 2.9 mm. The protrusions (139) may be highest at the center of the protrusion, and the height may become smaller as they go toward the edge. The height of the protrusion (139) may be the height from the lower surface (130b) of the first collector plate (130). In addition, the upper surface (130a) of the first collector plate (130) may be in the shape of a flat plate.

[0117] If the planar diameter of the protrusion (139) is less than about 1 mm, the height of the protrusion (139) cannot be increased to more than about 0.4 mm, so that the protrusion (139) may not easily contact the upper surface (110a) of the electrode assembly (110). In addition, if the planar diameter of the protrusion (139) exceeds about 15 mm, the number of protrusions (139) that can be provided on the lower surface (130b) of the first collector plate (130) is reduced, so that the area in contact with the upper surface (110a) of the electrode assembly (110) may not actually increase.

[0118] The protrusion (139) may be difficult to provide and form if its maximum height is less than approximately 0.4 mm. If the maximum height of the protrusion (139) exceeds approximately 2.9 mm, the height of the protrusion (139) may cause it to come into contact with the second electrode plate (112) within the electrode assembly (110), resulting in a short circuit.

[0119] The plane shape of such a protrusion (139) may have an elliptical or polygonal shape, and the shape may be changed in various ways.

[0120] In addition, the protrusion (139) can increase the contact area with the upper surface (110a) of the electrode assembly (110) by making the surface rougher than other areas through roughening treatment. That is, the first collector plate (130) can make easier contact with the upper surface (110a) of the electrode assembly (110) through surface roughness compared to when it only has the protrusion (139), thereby reducing the contact resistance. Here, a greater surface roughness may mean that the average height and / or maximum height in a plane and / or in a one-way line is larger through roughening treatment. The protrusion (139) can increase the surface roughness through roughening treatment. In one or more embodiments, the roughening treatment may be blasting, polishing, etching, or carbon high-temperature heat treatment.

[0121] The protrusion (139) may have a maximum height (Ry) of surface roughness of about 7 µm to about 9 µm, and an average height (Ra) of surface roughness of about 0.6 µm to about 0.9 µm. If the average height of the surface roughness of the protrusion (139) is less than about 0.6 µm, it may be difficult to increase the contact area with the upper surface (110a) of the electrode assembly (110) compared to when only the protrusion (139) is provided. If the average height of the surface roughness of the protrusion (139) is greater than about 0.9 µm or the maximum height is greater than about 9 µm, the electron movement path along the surface may be reduced due to the roughness, which may increase the resistance. The maximum height of the surface roughened protrusion (139) may be less than about 2.9 mm.

[0122] Referring to FIGS. 10 to 12, another example of a cross-sectional view taken along line A-A' of FIG. 8 is illustrated. FIGS. 10 to 12 illustrate another example of a cross-sectional view of the first collector plate (130).

[0123] Referring to FIG. 10, the first collector plate (130) may have a surface roughness not only on the surface of the protrusion (139), but also on the entire lower surface (130a) of the electrode plate connection portion (132) of the first collector plate (130). The entire lower surface (130a) of the electrode plate connection portion (132) of the first collector plate (130) may be roughened, thereby increasing contact with the upper surface (110a) of the electrode assembly (110). As another example, the entire lower surface (130a) of the first collector plate (130) may be roughened, thereby increasing the surface roughness of the lower surface (130a) of the terminal connection portion (131).

[0124] Referring to Fig. 11, the first collector plate (130) may further have a concave portion (139a) formed at a position corresponding to the position of the protrusion (139) on the upper surface (130a). That is, the protrusion (139) of the first collector plate (130) may be formed by pressing the flat first collector plate (130), so that the concave portion (139a) may be formed on the upper surface (130a) opposite to the surface on which the protrusion (139) is formed.

[0125] Referring to Fig. 12, the height of the protrusion (139) of the first collector plate (130) may be different. For example, the height (H1) of the winding tip protrusion (139x) that comes into contact with the winding tip region of the electrode assembly (110) adjacent to the terminal connection portion (131) and the height (H2) of the winding end protrusion (139y) that comes into contact with the winding end of the electrode assembly (110) may be equal to or lower than the height (H3) of the protrusion (139z) located in the intermediate region, which is another region.

[0126] This means that the electrode assembly (110) may have a cumulative thickness, which is a height at which the first electrode tab (111b) is bent and compacted, higher in the central region than at the winding tip and the winding end. For example, the electrode assembly (110) may have a cumulative thickness of the first electrode tab (111b) of approximately 0.2 mm or less at the winding tip and the winding end, and may be approximately 0.5 mm or less in the central region. Accordingly, the heights (H1, H2) of the winding tip protrusion (139x) and the winding end protrusion (139x) of the first collector plate (130) may be equal to or smaller than the height (H3) of the central region protrusion (139z). For example, the height (H3) of the central region protrusion (139z) may be approximately 0.4 mm to approximately 2.9 mm, and the heights (H1, H2) of the winding tip protrusion (139x) and the winding end protrusion (139x) may be approximately 0.4 mm to approximately 2.4 mm.

[0127] The second collector plate (140) may include a circular flat portion (141) corresponding to the lower surface (110b) of the electrode assembly (110), and an extension portion (142) extending downward from the edge of the flat portion (141).

[0128] Such a second collector plate (140) may further be provided with a protrusion (149) on the upper surface (140a) of the flat portion (141). The protrusion (149) may be provided to protrude upward from the upper surface (140a) of the flat portion (141) of the second collector plate (140). A plurality of protrusions (139) may be provided on the upper surface (140a) of the flat portion (141) of the second collector plate (140) so as to be spaced apart from each other. There may be at least two protrusions (149) in the diametric direction. The shape and size of the protrusion (149) may be similar to the shape and size of the protrusion (139) of the first collector plate (130).

[0129] The protrusion (149) can increase the surface roughness through roughening treatment. The protrusion (149) can have a greater surface roughness than other areas of the second collector plate (140). The protrusion (149) can have a maximum roughness height (Ry) of about 4.6 µm to about 5.6 µm and an average roughness height (Ra) of about 0.39 µm to about 0.44 µm. When the average roughness height of the protrusion (149) of the second collector plate (140) is less than about 0.39 µm, it may be difficult to increase the contact area between the second collector plate (140) and the lower surface (110b) of the electrode assembly (110) compared to when only the protrusion (149) is provided. If the average height of the roughness of the protrusion (149) of the second collector plate (140) is greater than approximately 0.44 ㎛ or the maximum height (Ry) is greater than approximately 5.6 ㎛, the electron movement path along the surface may be reduced, thereby increasing resistance.

[0130] The upper surface of the flat portion (141) of the second collector plate (140) can be in contact with and electrically connected to the lower surface (110b) of the electrode assembly (110). The upper surface of the flat portion (141) can be fixed and electrically connected to the second electrode tab (112b) exposed to the lower portion of the electrode assembly (110) by welding while in contact with the lower surface (110b) of the electrode assembly (110). Here, the flat portion (141) may not be provided with a protrusion (149) in the welding area where it is welded to the lower surface (110b) of the electrode assembly (110).

[0131] The extension portion (142) may extend downward from the edge of the flat portion (141). For example, a plurality of extension portions (142) may be provided so as to be spaced apart from each other along the edge of the flat portion (141). In addition, the extension portion (142) may be in contact with the inner surface of the beading portion (123). That is, the extension portion (142) may be rounded or bent along the beading portion (123). Here, the inner surface may be the inner surface of the case (120). The end of the extension portion (142) may be positioned between the beading portion (123) and the cap gasket (127). Such an extension portion (142) may be in contact with and joined to the beading portion (123) of the case (120). For example, the extension portion (142) may be joined by welding while in contact with the inner surface of the beading portion (123) of the case (120). The above second collector plate (140) serves as a current flow path between the second electrode plate (112) of the electrode assembly (110) and the case (120). That is, the case (120) may be a negative terminal.

[0132] As another example, the second collector plate (140) may increase surface roughness by roughening only the area where the flat portion (141) is located on the upper surface (140a). In this case, the surface roughness of the upper surface of the flat portion (141) and the surface of the protrusion (149) of the second collector plate (140) may be greater than that of the extended portion (142). That is, the surface roughness of the flat portion (141) and the protrusion (149) of the second collector plate (140) on the upper surface (140a) may be greater than or equal to that of the extended portion (142). In addition, the height of the protrusion (149) of the second collector plate (140) may be similar to that of the first collector plate (130) illustrated in FIG. 12, and the formation of the protrusion (149) may be formed by pressing, so that a groove corresponding to the protrusion (149) may be provided on the lower surface of the second collector plate (140).

[0133] Since the secondary battery (100) as described above has surface roughness on the upper surface (110a) and the lower surface (110b) due to the bending and compaction of the first electrode tab (111b) and the second electrode tab (112b) of the electrode assembly (110), the contact resistance between the electrode assembly (110) and the first collector plate (130) and between the electrode assembly (110) and the second collector plate (140) can be reduced by providing protrusions (139, 149) in the area where the electrode assembly (110) comes into contact with the first collector plate (130) and the second collector plate (140) to increase contact.

[0134] Figures 13 to 16 are plan views illustrating various examples of the first collector plate in the secondary batteries illustrated in Figures 1 to 6.

[0135] Referring to Fig. 13, the first current collector (230) may include a terminal connection portion (131), a plate connection portion (132), and a fuse portion (235). The fuse portion (235) may include a fuse hole (136), a plate connection portion (137), and a protrusion hole (236a). The protrusion hole (236a) may be formed at one end and the other end of the fuse hole (136), respectively. The protrusion holes (236a) formed at both ends of the fuse hole (136) may protrude in a direction approaching each other. The width of the protrusion hole (236a) may be smaller than the width of the fuse hole (136). The protrusion hole (236a) may reduce the width (W2) of the plate connection portion (137), i.e., the cross-sectional area through which current flows, thereby improving the function of the fuse portion (235).

[0136] Referring to Fig. 14, the first collector plate (330) may include a terminal connection portion (131), a plate connection portion (132), and a fuse portion (335). The fuse portion (335) may include a fuse hole (136), a plate connection portion (337), a protrusion hole (236a), and an extension hole (336b). The extension holes (336b) may extend from both ends of the fuse hole (136) toward the outside of the first collector plate (330) by the length of the plate connection portion (337). The extension holes (336b) formed at both ends of the fuse hole (136) may be parallel to each other. The extension holes (336b) may increase the length (L) of the plate connection portion (337), i.e., the length through which current flows, thereby improving the function of the fuse portion (335).

[0137] Referring to Fig. 15, the first collector plate (430) may include a terminal connection portion (131), a plate connection portion (132), and a fuse portion (435). The fuse portion (435) may include two fuse holes (436) spaced apart from each other, and two plate connection portions (437) positioned between the fuse holes (436). The two fuse holes (436) are positioned concentrically with respect to the center of the first collector plate (430) and may be symmetrical to each other. The angle (b) formed by the plate connection portion (437) with respect to the center of the first collector plate (430) may be about 30 to 50 degrees.

[0138] Referring to FIG. 16, the first collector plate (530) may include a terminal connection portion (131), a plate connection portion (132), and a fuse portion (535). The fuse portion (535) may include three fuse holes (536) spaced apart from each other, and three plate connection portions (537) positioned between the fuse holes (536). The three fuse holes (536) may be positioned concentrically with respect to the center of the first collector plate (530) and may be formed to have the same size. The angle (c) formed by the plate connection portions (537) with respect to the center of the first collector plate (530) may be about 8 to 15 degrees.

[0139] FIG. 17 is a cross-sectional view illustrating an exemplary secondary battery (100') according to the present disclosure. The secondary battery (100') illustrated in FIG. 17 may have a terminal (150) coupled to a cap plate (160). Additionally, a second electrode tab (112b) of an electrode assembly (110) may be directly welded to a lower portion (122') of a case (120').

[0140] The case (120') may include a lower portion (122') and a body portion (121) extending upward from the edge of the lower portion (122'). In addition, the lower portion (122') may include a safety vent (122a) that is thinner than other areas due to a notch. In the event that gas is generated due to overcharging or abnormal operation of the secondary battery (100'), the safety vent (122a) provided in the case (120') may be cut along the notch. The cut safety vent (122a) may release gas to the outside to prevent an explosion of the secondary battery (100').

[0141] The cap plate (160') can be joined by welding to the upper end, which is the end of the body part (121). In addition, a terminal (150) can be joined to a terminal hole provided in the cap plate (160'). Of course, the cap plate (160') and the terminal (150) can be electrically separated by a terminal gasket (125). The other configuration of the secondary battery (100') can be similar to the secondary battery (100) illustrated in FIGS. 1 and 2.

[0142] The secondary battery according to the above-described embodiment can be used to manufacture a battery pack.

[0143] FIGS. 18A and 18B are perspective views illustrating a battery pack including an exemplary secondary battery (100) according to the present invention. Referring to FIGS. 18A and 18B, the battery pack (300) may include a plurality of battery modules (200) and a housing (310) for accommodating the plurality of battery modules (200). For example, the housing (310) may include first and second housings (311, 312) that are coupled in a direction facing each other with the plurality of battery modules (200) interposed therebetween. The plurality of battery modules (200) may be electrically connected to each other using a bus bar (251), and the plurality of battery modules (200) may be electrically connected to each other in a series / parallel or series-parallel hybrid manner to obtain a required electrical output. In the drawings, for convenience of illustration, components such as a bus bar, a cooling unit, and an external terminal for electrically connecting battery cells are omitted. In some examples, the battery pack (300) may be mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may include a four-wheeled vehicle or a two-wheeled vehicle.

[0144] Figures 19a and 19b are perspective views and side views illustrating a vehicle (400, 500) including an exemplary battery pack (300) according to the present invention. In Figure 19a, the battery pack (300) may include a battery pack cover (311) (which may correspond to the first housing) which is a part of a vehicle underbody (410) and a pack frame (312) (which may correspond to the second housing) which is disposed at a lower portion of the vehicle underbody (410). The battery pack cover (311) and the pack frame (312) may be formed integrally with the vehicle floor (420). The vehicle underbody (410) separates the interior and exterior of the vehicle, and the pack frame (312) may be disposed at the exterior of the vehicle.

[0145] As illustrated in FIG. 19b, the vehicle (500) may be formed by combining additional components, such as a hood (510) at the front of the vehicle and fenders (520) positioned at the front and rear of the vehicle, respectively, with the vehicle body (400). The vehicle (500) includes a battery pack (300) including a battery pack cover (311) and a pack frame (312), and the battery pack (300) may be combined with the vehicle body component (400).

[0146] The above description is only one embodiment for implementing the secondary battery according to the present invention, and the present invention is not limited to the above-described embodiment, and as claimed in the following claims, it will be understood that the technical spirit of the present invention exists to the extent that various modifications can be implemented by anyone having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention.

[0147] The above description is only one embodiment for implementing the secondary battery according to the present invention, and the present invention is not limited to the above-described embodiment, and as claimed in the following claims, it will be understood that the technical spirit of the present invention exists to the extent that various modifications can be implemented by anyone having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention.

Claims

1. An electrode assembly having a first electrode plate, a separator, and a second electrode plate; A case in which the electrode assembly is accommodated; a terminal penetrating the case; and A first collector plate is interposed between the upper surface of the electrode assembly and the case, and electrically connects the first electrode plate and the terminal. A secondary battery in which the first collector plate includes a lower surface that contacts the upper surface of the electrode assembly and an upper surface opposite the lower surface, the lower surface of the first collector plate having a protrusion that protrudes in the direction of the electrode assembly, and the surface roughness of the protrusion is greater than the surface roughness of the upper surface of the first collector plate.

2. In paragraph 1, The above first collector plate is in the shape of a circular plate. A terminal connection portion that contacts and is electrically connected to the lower surface of the terminal; and A secondary battery including a first electrode tab exposed on the upper surface of the electrode assembly and electrically connected to the electrode plate connection portion, the electrode plate connection portion being located on the outer side of the terminal connection portion.

3. In paragraph 2, The above electrode plate connection portion extends in the diametric direction and has a welding area welded to the upper surface of the electrode assembly, The protrusion is provided in an area other than the above welding area, A secondary battery having at least two protrusions provided in the diameter direction of the electrode plate connecting portion.

4. In paragraph 3, A secondary battery in which the upper surface of the above-mentioned electrode connection part is a flat plane.

5. In paragraph 3, A secondary battery in which the upper surface of the above-mentioned electrode connection portion is provided with a concave portion corresponding to the above-mentioned protrusion portion.

6. In paragraph 3, A secondary battery in which the lower surface of the above-mentioned electrode plate connection portion is roughened, and the surface roughness is greater than that of the upper surface of the above-mentioned electrode plate connection portion.

7. In paragraph 3, The above protrusion is a secondary battery in which the height of the winding tip protrusion that comes into contact with the winding tip region of the electrode assembly and the height of the winding end protrusion that comes into contact with the winding end of the electrode assembly are equal to or lower than the height of the intermediate region protrusion located in the intermediate region other than the above protrusion.

8. In paragraph 1, The first electrode plate further includes a plurality of first electrode tabs that protrude upward from the upper surface of the electrode assembly and are bent and pressed in the winding axis direction of the electrode assembly, A secondary battery in which the second electrode plate protrudes downward from the lower surface of the electrode assembly and further includes a plurality of second electrode tabs bent and pressed in the winding axis direction of the electrode assembly.

9. In paragraph 8, The above electrode assembly is a secondary battery in which the cumulative thickness, which is the height at which the first electrode tab is bent and compacted, is higher in the central area than in the winding leading end and the winding ending.

10. In paragraph 8, A secondary battery further comprising a second collector plate in a circular plate shape corresponding to the lower surface of the electrode assembly and in contact with and electrically connected to the second electrode tab exposed to the lower surface of the electrode assembly.

11. In paragraph 10, The second collector plate has a circular flat surface in contact with the lower surface of the electrode assembly; and A secondary battery including an extension portion extending downward from an edge of the flat portion and in contact with the case.

12. In paragraph 11, A secondary battery in which the above-mentioned flat portion includes a plurality of protrusions protruding in the lower direction of the electrode assembly on the upper surface of the second collector plate, and the surface roughness of the protrusions is greater than the surface roughness of the lower surface of the second collector plate.

13. In paragraph 12, A secondary battery in which the surface roughness of the upper surface of the second collector plate is greater than the surface roughness of the lower surface of the second collector plate.

14. In paragraph 1, The case comprises an upper portion; and a body portion extending downward from an edge of the upper portion, The secondary battery having the terminal penetrating the upper part of the case and connected to the first collector plate.

15. In paragraph 14, A secondary battery, wherein the case further includes a cap plate that seals the lower end of the body.

16. In paragraph 1, The case comprises a lower portion; and a body portion extending upward from an edge of the lower portion, A secondary battery further comprising a cap plate that seals the upper end of the body.

17. In paragraph 16, A secondary battery in which the terminal penetrates the cap plate and is connected to the first collector plate.

18. In paragraph 8, The above electrode assembly is a secondary battery having a surface roughness on the lower surface greater than that on the upper surface.

19. In paragraph 8, A secondary battery in which the plurality of first electrode tabs are arranged in a plurality of first uncoated portions on the first electrode plate to which no electrode active material is applied, and are spaced apart from each other along the winding direction.

20. In paragraph 8, A secondary battery in which the above plurality of first electrode tabs are not provided at the winding tip and winding end of the first electrode plate.

Images