Secondary battery with electrode plates having improved flatness and method of manufacturing same
Patent Information
- Application Number
- KR1020250028114
- Authority / Receiving Office
- KR · KR
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-03-05
- Publication Date
- 2026-09-14
Smart Images
Figure PAT00004_ABST
Abstract
Description
Technology Field
[0001] The present invention relates to a secondary battery, and more specifically, to a secondary battery comprising an electrode plate having improved flatness and a method for manufacturing the same. Background Technology
[0003] Unlike primary batteries, which cannot be recharged, secondary batteries are batteries that can be charged and discharged. Generally, a secondary battery includes an electrode assembly consisting of positive and negative electrode plates and a separator.
[0004] The above positive or negative electrode plate can be manufactured by undergoing a coating process in which an active material composite is coated on one or both sides of a substrate, a rolling process in which the electrode plate coated with the composite by the coating process is compressed and stretched to make the electrode plate thin and flat, a slitting process in which the electrode plate coated in multiple rows is cut in the longitudinal direction to separate it into individual electrode plates, a notching process in which each separated electrode plate is cut in the transverse direction and unnecessary parts are removed, and a process of attaching an electrode tab to the uncoated portion of the electrode plate substrate.
[0005] One or more electrode tabs are attached to the electrode plate constituting the electrode assembly used in a secondary battery, and various lamination tapes may be attached depending on the case. The flatness of the electrode plate may be affected by a step difference caused by a height difference between the electrode plate substrate and the electrode tabs or lamination tapes.
[0006] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art. The problem to be solved
[0008] The present invention proposes a method for improving the flatness of an electrode plate constituting an electrode assembly. means of solving the problem
[0010] According to one aspect of the present invention for solving the above technical problem, a secondary battery is provided comprising: an electrode assembly including an electrode plate including an electrode tab attached to an electrode plate substrate; and an outer material in which the electrode assembly is housed, wherein the electrode plate of the electrode assembly further comprises a first flatness reinforcing layer applied to a stepped portion between the surface of the electrode tab and the surface of the electrode plate substrate.
[0011] According to another aspect of the present invention for solving the above technical problem, a method for manufacturing a secondary battery is provided, comprising the steps of: producing an electrode plate by coating an electrode material on a substrate; welding an electrode tab to the substrate of the produced electrode plate; applying a first flatness reinforcement layer to a stepped portion resulting from a height difference between the surface of the electrode tab and the surface of the substrate; producing an electrode assembly by winding the electrode plate to which the flatness reinforcement layer is applied; and housing the electrode assembly in a secondary battery casing.
[0012] However, the technical problems and means of solution that the present invention aims to solve are not limited to the above-mentioned contents, and other unmentioned problems and means of solution can be clearly understood by those skilled in the art from the description of the invention below. Effects of the invention
[0014] According to the present invention, the flatness of the electrode plates constituting the electrode assembly can be uniformly improved, thereby maximizing the space utilization and stacking density of the electrode plates of the secondary battery, which can result in an increase in capacity. Additionally, uniform electrochemical behavior (e.g., lithium ion mobility) between the flat electrode plates can be induced, which suppresses the increase in internal resistance, thereby extending the lifespan and improving the safety of the secondary battery.
[0015] The effects obtainable through the present invention are not limited to those described above, and other unmentioned technical effects will be clearly understood by those skilled in the art from the description of the invention below. Brief explanation of the drawing
[0017] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in the drawings. FIG. 1 schematically illustrates the appearance of a secondary battery electrode assembly according to some embodiment of the present invention. FIG. 2 schematically illustrates the external appearance of an electrode assembly according to another embodiment of the present invention. Figure 3 is a view of the electrode assembly of Figure 2 from the electrode tab side, intended to show the winding structure of each electrode plate. Figure 4a shows the unfolded state of the first electrode plate shown in Figure 3. Figure 4b shows the state in which the opposite side of the first electrode plate shown in Figure 4a is shown. Figure 5a shows the unfolded state of the second electrode plate shown in Figure 3. Figure 5b shows the state in which the opposite side of the second electrode plate shown in Figure 5a is shown. FIG. 6 is a flowchart of a method for manufacturing an electrode assembly according to some embodiments of the present invention. FIG. 7 is a flowchart of a method for manufacturing an electrode assembly according to another embodiment of the present invention. FIG. 8 shows a pouch-type secondary battery to which an electrode assembly according to some embodiment of the present invention is applied. FIG. 9 shows a cylindrical secondary battery to which an electrode assembly according to some embodiment of the present invention is applied. FIG. 10 shows a prismatic secondary battery to which an electrode assembly according to some embodiment of the present invention is applied. Figure 11 is an example of a secondary battery pack. Figure 12 is an example of a car equipped with a secondary battery pack. Specific details for implementing the invention
[0018] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Instead, based on the principle that the inventor can appropriately define the concepts of terms to best describe their invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely some preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. It should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.
[0019] Additionally, as used herein, “comprise, include” and / or “comprising, including” specify the presence of the mentioned features, numbers, steps, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, numbers, actions, parts, elements, and / or groups thereof.
[0020] Additionally, to aid in understanding the invention, the attached drawings are not drawn to actual scale, and the dimensions of some components may be exaggerated. Furthermore, the same reference numerals may be assigned to identical components in different embodiments.
[0021] The statement that two subjects of comparison are "identical" means that they are "substantially identical." Therefore, substantial identity may include deviations considered low in the industry, for example, deviations within 5%. Additionally, the statement that a parameter is uniform in a given area may mean that it is uniform from an average perspective.
[0022] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.
[0023] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.
[0024] The fact that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.
[0025] Furthermore, where one component is described as being "on," "connected to," or "coupled to" another component, it should be understood that while the components may be directly connected or coupled to each other, another component may be "interposed" between each component, or that each component may be "connected," "coupled," or "coupled" through another component.
[0026] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Additionally, the use of “may” when describing embodiments of the invention relates to “one or more embodiments of the invention.” Expressions such as “one or more” and “one or more” preceding a list of elements modify the entire list of elements and do not modify individual elements of the list.
[0027] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less, unless specifically stated otherwise.
[0028] When syntax such as "at least one of A, B, and C", "at least one of A, B, or C", "at least one selected from the group of A, B, and C", or "at least one selected from A, B, and C" is used to specify a list of elements A, B, and C, the syntax can refer to any suitable combination.
[0029] The term "use" may be considered synonymous with the term "utilize." As used herein, terms such as "substantially," "about," and similar terms are used as terms of approximation rather than degree, and are intended to account for the inherent variation of a measured or calculated value that would be recognized by a person skilled in the art.
[0030] In this specification, terms such as first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Accordingly, the first element, component, region, layer, or section discussed below may be named the second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.
[0031] For ease of explanation in describing the relationship between one element or feature and another element(s) or feature(s) as illustrated in the drawings, spatial relative terms such as "beneath," "below," "lower," "above," and "upper" may be used in the specification. Spatially relative positions are to be understood as encompassing different orientations of the device in use or operation, in addition to the orientations depicted in the figures. For example, if the device in the drawing is inverted, the other element is understood as "below" or "below," and the described element is understood as "above" or "upper" of the other element. Thus, the term "below" may encompass both the up and down directions.
[0032] The terms used in this specification are for describing embodiments of the invention and are not intended to limit the invention.
[0034] FIG. 1 schematically illustrates the appearance of a secondary battery electrode assembly according to some embodiment of the present invention.
[0035] As described above, the electrode assembly (10) can be formed by winding a first electrode plate (11), a separator (12), and a second electrode plate (13). Since the electrode assembly (10) is configured by winding the first electrode plate (11), the separator (12), and the second electrode plate (13) into a roll shape, it is called a wound electrode assembly or a jelly roll. The first electrode plate (11) of the electrode assembly (10) can act as a negative electrode and the second electrode plate (13) can act as a positive electrode, and vice versa.
[0036] The first electrode plate (11), when it is a negative electrode, is formed by applying a first electrode active material, such as graphite or carbon, to a first substrate formed of a metal foil such as copper, a copper alloy, nickel, or a nickel alloy, and may include a first electrode tab (14), which is an area where the first electrode active material is not applied. The first electrode tab (14) may be connected to an external first terminal (not shown). In some examples, the first electrode tab (14) may be formed by cutting it to protrude to one side in advance when manufacturing the first electrode plate (11), and may protrude further to one side than the separator (12) without separate cutting.
[0037] The second electrode plate (13), in the case of a positive electrode, is formed by applying a second electrode active material, such as a lithium transition metal oxide, to a second substrate formed of a metal foil such as aluminum or an aluminum alloy, and may include a second electrode tab (15) which is an area where the second electrode active material is not applied. The second electrode tab (15) may be connected to an external second terminal (not shown). In some examples, the second electrode tab (15) may be formed by cutting it to protrude to the other side when manufacturing the second electrode plate (13), and may protrude further to the other side than the separator (12) without separate cutting.
[0038] The separator (12) functions to prevent short circuits between the first electrode plate (11) and the second electrode plate (13) while allowing the movement of lithium ions. The separator (12) may be composed of, for example, a polyethylene film, a polypropylene film, a polyethylene-polypropylene film, etc.
[0039] In some embodiments, the electrode assembly (10) may be housed in a case (not shown) and filled with an electrolyte. In the case of a pouch-type secondary battery, the electrode assembly (10) may be housed in a pouch made of a flexible material, and in the case of a cylindrical or prismatic secondary battery, the electrode assembly (10) may be housed in a cylindrical or prismatic metal case.
[0041] A material that can be used in an electrode assembly including an electrode plate applied to the secondary battery of the present invention is described.
[0042] As a positive electrode active material, a compound capable of reversible intercalation and deintercalation of lithium (a lithated intercalation compound) may be used. Specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used.
[0043] The above composite oxide may be a lithium transition metal composite oxide, and specific examples include a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, a cobalt-free nickel-manganese-based oxide, or a combination thereof.
[0044] As an example, a compound represented by any one of the following chemical formulas may be used. Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G eO2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).
[0045] In the above 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; L 1 is Mn, Al, or a combination thereof.
[0046] A positive electrode for a lithium secondary battery may include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer may include a positive electrode active material and may further include a binder and / or a conductive material.
[0047] The content of the positive active material is 90% to 99.5% by weight with respect to 100% by weight of the positive active material layer, and the content of the binder and the conductive material may each be 0.5% to 5% by weight with respect to 100% by weight of the positive active material layer.
[0048] Al can be used for the above-mentioned current collector, but is not limited thereto.
[0049] 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.
[0050] A material capable of reversibly intercalating / deintercalating the above lithium ions may be a carbon-based negative electrode active material, such as 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, etc.
[0051] As a material capable of doping and dedoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The above Si-based negative electrode active material is silicon, a silicon-carbon composite, SiOx (0 <x≤2), Si계 합금, 또는 이들의 조합일 수 있다.
[0052] The 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.
[0053] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core.
[0054] A negative electrode for a lithium secondary battery comprises a current collector and a negative electrode active material layer located on the current collector. The negative electrode active material layer comprises a negative electrode active material and may further comprise a binder and / or a conductive material.
[0055] For example, the negative electrode active material layer may comprise 90% to 99% by weight of negative electrode active material, 0.5% to 5% by weight of binder, and 0% to 5% by weight of conductive material.
[0056] As the binder, a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof may be used. When an aqueous binder is used as the cathode binder, a cellulose-based compound capable of imparting viscosity may be further included.
[0057] As the above-mentioned cathode current collector, a material selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof may be used.
[0058] The electrolyte for lithium secondary batteries contains a non-aqueous organic solvent and a lithium salt.
[0059] The above-mentioned non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.
[0060] The above-mentioned 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 a mixture of two or more types.
[0061] In addition, when using carbonate-based solvents, cyclic carbonates and chain carbonates can be mixed and used.
[0062] Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. As such a separator, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used.
[0063] The above separator may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.
[0064] The above organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.
[0065] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include, but is not limited to, inorganic particles selected from SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.
[0066] The above organic and inorganic materials may exist mixed in a single coating layer, or may exist in a stacked form with a coating layer containing organic materials and a coating layer containing inorganic materials.
[0068] FIG. 2 schematically illustrates the appearance of an electrode assembly (10') according to another embodiment of the present invention.
[0069] The current capacity is increased by adding electrode tabs (14', 15') to the electrode assembly (10') shown in FIG. 1. As shown in FIG. 2, a structure in which multiple electrode tabs (14, 14', 15, 15') are formed is called a multi-tap structure. In the electrode assembly (10') of the multi-tap structure, the first electrode tabs (14, 14') and the second electrode tabs (15, 15') can be welded to each other, and terminals exposed to the outside can be electrically connected to these welded electrode tabs.
[0070] In FIG. 2, the substrate and electrode material of the first electrode plate (11) and the second electrode plate (13), and the material of the separator (12) are virtually identical to those described above for the electrode assembly (10) of FIG. 1, so a detailed description is omitted.
[0072] FIG. 3 is a view of the electrode assembly (10') of FIG. 2 from the electrode tabs (14, 14', 15, 15') to show the winding structure of each electrode plate. For ease of understanding, the separator (12) is not shown.
[0073] In the electrode assembly (10') of FIG. 3, the first electrode plate (11a, 11b, 11c, 11d) is assumed to be the positive electrode (+) and the second electrode plate (13a, 13b, 13c, 13d) is assumed to be the negative electrode (-), but the present invention is not limited thereto.
[0074] In the wound electrode assembly (10') according to the embodiment illustrated in FIG. 3, the positive electrode plate (positive plate) has a first two-sided uncoated portion (11a), which is a section where the positive material is not coated on both sides of the substrate, located at the outermost part to form the outer finishing portion. Additionally, as the positive plate enters the core of the electrode assembly (10'), it is sequentially composed of a single-sided uncoated portion (11b), which is a section where the positive material is coated on only one side of the substrate; a two-sided coated portion (11c), which is a section where the positive material is coated on both sides of the substrate; and a second two-sided uncoated portion (11d), which is a section where the positive material is not coated on both sides of the substrate. A first positive electrode tab (14) is attached to the second two-sided uncoated portion (11d) located in the core.
[0075] Additionally, a second electrode tab (14') is attached to the first two-sided unfinished portion (11a) having an outer finished surface in a position parallel to the first electrode tab (14). The first electrode tab (14) and the second electrode tab (14') can be welded together. Although two electrode tabs, the first electrode tab (14) and the second electrode tab (14'), are shown in FIG. 3, a greater number of electrode tabs is also possible.
[0076] In addition, in FIG. 3, the negative electrode plate (negative plate) is located inside the positive plate, and as it moves from the outside of the electrode assembly (10') into the core, it is composed of a first two-sided uncoated section (13a), which is a section where the negative material is not coated on both sides of the substrate; a two-sided coated section (13b), which is a section where the negative material is coated on both sides of the substrate; a single-sided uncoated section (13c), which is a section where the negative material is coated on only one side of the substrate; and a second two-sided uncoated section (13d), which is a section where the negative material is not coated on both sides of the substrate. A negative electrode tab (15) is attached to the second two-sided uncoated section (13d) located in the core.
[0077] Additionally, a second negative electrode tab (15') is attached to the first two-sided non-removable portion (11a) on the outer side in a position parallel to the first negative electrode tab (15). The first negative electrode tab (15) and the second negative electrode tab (15') can be welded together. Although two negative electrode tabs, the first negative electrode tab (15) and the second negative electrode tab (15'), are shown in FIG. 3, a greater number of negative electrode tabs is also possible.
[0078] As shown in FIG. 3, the first positive electrode tab (14), the second positive electrode tab (14'), the first negative electrode tab (15), and the second negative electrode tab (15') are each joined to the substrate of the corresponding electrode plate by welding, so a step difference S is created due to the height difference between the surface of each electrode tab and the surface of the substrate. These step differences S reduce the flatness of the final electrode assembly, and as a result, a bumpy electrode assembly may be produced. In addition, although not shown, if a lamination tape is attached to the electrode plate during the production of the electrode assembly, a step difference between the surface of the lamination tape and the surface of the electrode plate substrate is added, further worsening the flatness of the electrode plate. With the increase in energy capacity of secondary batteries recently becoming an important design factor, such deterioration in electrode plate flatness can hinder space utilization and stacking density of the secondary battery. Furthermore, uneven electrochemical behavior between electrode plates with poor flatness (e.g., lithium ion mobility) can increase internal resistance, shortening lifespan, and is disadvantageous in terms of mechanical rigidity, which can have an adverse effect on improving the performance of the secondary battery. Efforts are being made to improve the flatness of the electrode assembly of the secondary battery, particularly the wound electrode assembly, to 200 µm or less.
[0080] FIG. 4a shows the unfolded state of the first electrode plate (11) (positive electrode in this embodiment) shown in FIG. 3.
[0081] A flatness reinforcing layer may be applied around a first electrode tab (14) attached to one side of a second two-sided unoccupied portion (11d) in the core and a second electrode tab (14') attached to one side of a first two-sided unoccupied portion (11a) forming an outer finish. For example, the flatness reinforcing layer may include a lower flatness reinforcing layer (11e) applied to a stepped portion that may occur at the bottom of the electrode tabs (14, 14'), and / or a side flatness reinforcing layer (11f) applied to a stepped portion that may occur on the left or right side of the electrode tabs (14, 14').
[0082] Meanwhile, the first electrode tab (14) and / or the second electrode tab (14') may be attached to the opposite side of the display surface of the first electrode plate (11) shown in FIG. 4a. FIG. 4b shows the first electrode plate (11) shown in FIG. 4a in a flipped state so that the opposite side is visible. Similar to the case of FIG. 4a, a flatness reinforcing layer may be applied around the first electrode tab (14) attached to the other side of the second two-sided unoccupied portion (11d) in the core and the second electrode tab (14') attached to the other side of the first two-sided unoccupied portion (11a) forming the outer finish. Likewise, the flatness reinforcing layer may include a lower flatness reinforcing layer (11e) applied to the lower stepped portion of each electrode tab (14, 14') and a side flatness reinforcing layer (11f) applied to the stepped portion of the left or right side of each electrode tab (14, 14').
[0083] In some embodiments, the flatness reinforcing layer (11e, 11f) may be applied by applying an insulating material to the corresponding area of the electrode plate substrate. The insulating material used may be, for example, PI (polyimide) or a similar material (polysulfone, polyphenylsulfone, polyethersulfone, polyphenylene sulfide, etc.), ceramic, photocurable resin, etc. In other embodiments, the flatness reinforcing layer (11e, 11f) may be applied by attaching an insulating tape to the corresponding area of the electrode plate substrate.
[0085] FIG. 5a shows the unfolded state of the second electrode plate (13) (in this embodiment, the negative electrode) shown in FIG. 3.
[0086] A flatness reinforcing layer may be applied around a first negative electrode tab (15) attached to one side of a second two-sided non-reinforcing portion (13d) located in the core and a second negative electrode tab (15') attached to one side of a first two-sided non-reinforcing portion (13a) located on the outside. The flatness reinforcing layer may include a lower flatness reinforcing layer (13e) applied to the lower stepped portion of the electrode tabs (15, 15') and a side flatness reinforcing layer (13f) applied to the left and right stepped portions of the electrode tabs (15, 15').
[0087] Meanwhile, the first negative electrode tab (15) and / or the second negative electrode tab (15') may be attached to the opposite side of the display surface of the second electrode plate (13) shown in FIG. 5a. FIG. 5b shows the second electrode plate (13) shown in FIG. 5a in a flipped state so that the opposite side is visible. Similar to the case of FIG. 5a, a flatness reinforcing layer may be applied around the first negative electrode tab (15) attached to the other side of the second two-sided unoccupied portion (13d) in the core and the second negative electrode tab (15') attached to the other side of the first two-sided unoccupied portion (13a) in the outer side. Likewise, the flatness reinforcing layer may include a lower flatness reinforcing layer (13e) applied to the lower stepped portion of each electrode tab (15, 15') and a side flatness reinforcing layer (13f) applied to the left and right stepped portions of each electrode tab (15, 15').
[0088] In some embodiments, the flatness reinforcing layer (13e, 13f) may be applied by applying an insulating material to the corresponding area of the electrode plate substrate. The insulating material used may be, for example, PI (polyimide) or a similar material (polysulfone, polyphenylsulfone, polyethersulfone, polyphenylene sulfide, etc.), ceramic, photocurable resin, etc. In other embodiments, the flatness reinforcing layer (13e, 13f) may be applied by attaching an insulating tape to the corresponding area of the electrode plate substrate.
[0090] FIG. 6 is a flowchart of a method for manufacturing an electrode assembly according to some embodiments of the present invention.
[0091] An embodiment of a method for manufacturing an electrode assembly will be described with reference to FIGS. 3 to 5b described above.
[0092] 110: Coat the electrode material onto the substrate.
[0093] For example, as mentioned above, an electrode material is coated on one side and / or the other side of a substrate of a first electrode plate (11) which may be an anode plate, thereby forming a first two-sided uncoated portion (11a) in which the anode material is not coated on both sides of the substrate as shown in FIG. 3, a single-sided uncoated portion (11b) in which the anode material is coated on only one side of the substrate, a two-sided coated portion (11c) in which the anode material is coated on both sides of the substrate, and a second two-sided uncoated portion (11d) in which the anode material is not coated on both sides of the substrate.
[0094] In addition, an electrode material is coated on one side and / or the other side of a substrate of a second electrode plate (13) which may be a cathode plate, thereby forming a first two-sided uncoated portion (13a) in which the cathode material is not coated on both sides of the substrate as shown in FIG. 3, a two-sided coated portion (13b) in which the cathode material is coated on both sides of the substrate, a single-sided uncoated portion (13c) in which the cathode material is coated on only one side of the substrate, and a second two-sided uncoated portion (13d) in which the cathode material is not coated on both sides of the substrate.
[0095] 120: An electrode tab is welded to the substrate-free portion of each electrode plate (11, 13) manufactured as described above.
[0096] For example, in the first electrode plate (11), as shown in FIG. 3, a first positive electrode tab (14) can be welded to one side and / or the other side of the second two-sided unoccupied portion (11d) that will be located in the core of the electrode assembly after final winding. Additionally, a second positive electrode tab (14') can be welded to one side and / or the other side of the first two-sided unoccupied portion (11a) that will be located on the outside of the electrode assembly after final winding. Furthermore, in the second electrode plate (13) which may be a negative electrode plate, a first negative electrode tab (15) can be welded to one side and / or the other side of the second two-sided unoccupied portion (13d) that will be located in the core of the electrode assembly after final winding. Additionally, a second negative electrode tab (15') can be welded to one side and / or the other side of the first two-sided unoccupied portion (13a) that will be located on the outside of the electrode assembly after final winding.
[0097] 130: A first flatness reinforcing layer, in this case an insulating layer, is applied to the stepped portion that may be created due to the difference in height between the surface of the electrode tab and the surface of the substrate untreated portion.
[0098] For example, as shown in FIG. 4a or FIG. 4b, a first insulating layer may be applied to the stepped portions (e.g., lower and / or left and right sides) around the first electrode tab (14) welded to the second unpaired portion (11d) of the first electrode plate (11) and the second electrode tab (14') welded to the first unpaired portion (11a). Here, the "first" insulating layer (first flatness reinforcing layer) is named in correspondence with the "second" insulating layer (second flatness reinforcing layer) in FIG. 7, which will be described later. Meanwhile, as shown in FIG. 5a or 5b, a first insulating layer may be applied to the stepped portions (e.g., lower and / or left and right sides) around the first negative electrode tab (15) welded to the second uncoated portion (13d) on both sides of the second electrode plate (13) and the second negative electrode tab (15') welded to the first uncoated portion (13a) on both sides. Here, as mentioned above, insulating tape may be attached instead of applying an insulating layer. The material of the insulating layer to be applied may be, for example, PI (polyimide) or a similar material (polysulfone, polyphenylsulfone, polyethersulfone, polyphenylene sulfide, etc.), ceramic, photocurable resin, etc.
[0099] 140: An electrode assembly is fabricated by winding an electrode plate with an insulating layer (flatness reinforcement layer) applied.
[0100] For example, the first electrode plate (11) and the second electrode plate (13) are wound in a structure as shown in FIG. 3 to produce the electrode assembly (10) of FIG. 1 or the electrode assembly (10') of FIG. 2. When winding the first electrode plate (11) and the second electrode plate (13), a separator (12) is interposed between the first electrode plate (11) and the second electrode plate (13) and wound together, as described above with reference to FIG. 1.
[0101] Afterwards, the first electrode tab (14, 14') and the second electrode tab (15, 15') are welded respectively, and a strip conductor (not shown) is connected and placed in an outer material such as a pouch or can to manufacture a pouch-type, cylindrical-type, or prismatic secondary battery.
[0103] FIG. 7 is a flowchart of a method for manufacturing an electrode assembly according to another embodiment.
[0104] In the manufacturing method of FIG. 6, a first flatness reinforcing layer is applied to the stepped portion between the electrode plate substrate and the electrode tab attached thereto. However, during the manufacturing process of the electrode assembly (10), various lamination tapes may be attached to the electrode plate in addition to the electrode tab. A second flatness reinforcing layer may also be applied to the stepped portion that may occur between the electrode plate substrate and the lamination tape, similar to the electrode tab, to further ensure the improvement of the flatness of the electrode plate. FIG. 7 is a flowchart of a method for manufacturing such an electrode assembly.
[0105] 110: Coat the electrode material onto the substrate.
[0106] This step is virtually identical to step 110 described in Fig. 6, so the description is omitted.
[0107] 120: Weld electrode tabs to the unwelded portions of each electrode plate.
[0108] This step is also virtually identical to the 120 steps described in Fig. 6, so the explanation is omitted.
[0109] 130: A first insulating layer is applied to the step portion between the electrode tab and the substrate blank portion.
[0110] This step is also virtually identical to step 130 described in Fig. 6, so the explanation is omitted.
[0111] 150: In step 150, which is performed in addition to step 130 above, a second flatness reinforcing layer, here, an insulating layer is applied to the step between the lamination tape attached to the electrode plate and the electrode plate substrate.
[0112] As mentioned above, during the manufacturing process of the electrode assembly (10, 10'), if a step is created due to a height difference between the electrode plate and the lamination tape (not shown) attached to the electrode plate, a second flatness reinforcing layer is applied to this step. At this time, the second flatness reinforcing layer can also be applied in the same way as the first flatness reinforcing layer in step 130.
[0113] For example, as can be inferred from FIG. 4a or FIG. 4b, an insulating layer may be applied or an insulating tape may be attached to a stepped portion that may occur on the left or right side of a lamination tape (not shown) attached to the first electrode plate (11). Also, as can be inferred from FIG. 5a or FIG. 5b, an insulating layer may be applied or an insulating tape may be attached to a stepped portion that may occur on the left or right side of a lamination tape (not shown) attached to the second electrode plate (13).
[0114] 140: An electrode assembly is manufactured by winding electrode plates to which the first and second insulating layers (flatness reinforcing layers) are applied. When winding the electrode plates, a separator is interposed between the first electrode plate (11) and the second electrode plate (13) and wound together.
[0115] This step is also virtually identical to step 140 described in Fig. 6, so the explanation is omitted.
[0117] FIG. 8 schematically shows a pouch-type secondary battery to which an electrode assembly according to some embodiment of the present invention is applied.
[0118] The pouch-type secondary battery may be composed of an electrode assembly (10) and a pouch (20) that accommodates the electrode assembly (10). The first electrode tab (14) and the second electrode tab (15) of the electrode assembly (10) as shown in FIG. 1 may be electrically connected by welding to the external first strip terminal (16) and the second strip terminal (17), respectively. A tab film (18) for insulation from the pouch (20) may be attached to the first strip terminal (16) and the second strip terminal (17). The first strip terminal (16) and the second strip terminal (17) may be connected to a circuit board or electrical part of a battery application product (e.g., an electric device such as a mobile phone, tablet, or fan).
[0119] The pouch (20) can be sealed by the sealing portions (21) at the edges coming into contact with each other while the pouch (20) accommodates the electrode assembly (10), and sealing can be performed with a tab film (18) interposed between the sealing portions (21). The sealing portions (21) of the pouch (20) are made of a heat-fusion material, and since heat-fusion materials generally have weak adhesion to metal, a thin film-shaped tab film (18) can be interposed to fuse with the pouch (20).
[0121] FIG. 9 shows a cylindrical secondary battery to which an electrode assembly according to some embodiment of the present invention is applied.
[0122] This cylindrical secondary battery includes an electrode assembly (10, 10'), a case (38) that contains the electrode assembly (10, 10') and an electrolyte inside, a cap assembly (50) that is coupled to an opening of the case (38) and seals the case (38), and an insulating plate (37) located between the electrode assembly (10, 10') and the cap assembly (50) inside the case (38).
[0123] The case (38) accommodates the electrode assembly (10, 10') and the electrolyte, and together with the cap assembly (50), forms the outer shape of the battery. The case (38) may include a body portion (38b) in the shape of a rough cylinder and a bottom portion (38a) connected to one side of the body portion (38b). A beading portion (31) deformed toward the inside may be located in the body portion (38b), and a crimping portion (33) bent toward the inside may be located at the opening end of the body portion (38b).
[0124] The beading portion (31) can prevent the electrode assembly (10, 10') from moving inside the case (38) and facilitate the seating of the gasket (12) and the cap assembly (50). The crimping portion (33) can firmly secure the cap assembly (50) by pressing the edge of the cap assembly (50) through the gasket (12). The case (38) may be made of, for example, nickel-plated iron.
[0125] The cap assembly (50) can be fixed to the inside of the crimping portion (33) through the gasket (12) to seal the case (38). The cap assembly (50) may include a cap-up (51), a safety vent (52), a cap-down (53), an insulating member, and a subplate (54), but is not limited to these examples and can be modified in various ways.
[0126] The cap-up (51) may be located at the uppermost part of the cap assembly (50). The cap-up (51) may include a terminal portion that protrudes upward in a convex manner to be connected to an external circuit, and a discharge port for discharging gas may be located around the terminal portion.
[0127] The safety vent (52) may be located below the cap-up (51). The safety vent (52) may include a protrusion that protrudes downward in a convex manner and is connected to the subplate (54), and at least one notch located around the protrusion.
[0128] When gas is generated due to overcharging or abnormal operation of the secondary battery, the protrusion is deformed upward by pressure and separated from the subplate (54), while the safety vent (52) can be cut along the notch. The cut safety vent (52) can release the gas to the outside to prevent the explosion of the secondary battery.
[0129] The cap down (53) may be located below the safety vent (52). The cap down (53) may have a first opening for exposing the protrusion of the safety vent (52) and a second opening for gas discharge. An insulating member may be located between the safety vent (52) and the cap down (53) to insulate the safety vent (52) and the cap down (53).
[0130] The subplate (54) may be positioned below the cap-down (53). The subplate (54) may be fixed to the lower surface of the cap-down (53) to block the first opening of the cap-down (53), and the protrusion of the safety vent (52) may be fixed to the subplate (54). The first lead tab (35) drawn from the electrode assembly (10, 10') may be fixed to the subplate (54). Thus, the cap-up (51), safety vent (52), cap-down (53), and subplate (54) may be electrically connected to the first electrode (11) of the electrode assembly (10, 10').
[0131] An insulating plate (37) may be positioned to be in contact with an electrode assembly (10, 10') below the beading portion (13), and the insulating plate (37) may be provided with a tab opening for drawing out a first lead tab (35). A cap assembly (50) electrically connected to the first electrode (11) by the first lead tab (35) faces the electrode assembly (10, 10') with the insulating plate (37) in between, and may be insulated from the electrode assembly (10, 10') by the insulating plate (37). Meanwhile, another insulating plate (36) may be included for insulation between the electrode assembly (10, 10') and the bottom portion (38a) of the case (38).
[0133] FIG. 10 shows a prismatic secondary battery to which an electrode assembly according to some embodiment of the present invention is applied.
[0134] The separator functions to prevent a short circuit between the first electrode plate and the second electrode plate while allowing the movement of lithium ions. The separator may be composed of, for example, a polyethylene film, a polypropylene film, a polyethylene-polypropylene film, etc.
[0135] In some embodiments, the electrode assembly (10, 10') may be housed in a case (59) together with the electrolyte.
[0136] In the above electrode assembly (10, 10'), the first electrode tabs (43) and the second electrode tabs (44) protruding from the first electrode plate and the second electrode plate can be connected to the first current collector plate (41) and the second current collector plate (42), respectively.
[0137] The first current collector plate (41) and the second current collector plate (42) are each electrically connected to the first terminal (62) and the second terminal (63) through a connecting member (67). In some embodiments, the outer surface of the connecting member (67) may be screw-machined and may be fastened to the first terminal (62) and the second terminal (63) through screw connection. However, the present invention is not limited thereto, and the connecting member (67) may be joined to the first terminal (62) and the second terminal (63) by riveting or welding.
[0138] A secondary battery module can be manufactured by arranging and connecting secondary batteries according to the present invention in a transverse direction and / or a longitudinal direction. The arrangement direction and number of secondary batteries can be designed to obtain desired voltage and current specifications. A secondary battery pack (70) configured to apply the secondary battery module to an actual product (e.g., a vehicle) is illustrated in FIG. 11. The secondary battery pack can be manufactured by embedding a plurality of secondary battery modules in a pack housing designed for mounting on an actual product. The pack housing may include a fastening part and an electrical output part necessary for mounting on the product, as well as related elements such as a busbar for electrical connection of the secondary batteries, a cooling unit, and an external terminal. As shown in FIG. 12, the secondary battery pack can be mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle.
[0139] 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 obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols
[0141] 10 10' electrode assembly, 11 first electrode plate, 11a first uncoated side, 11b single uncoated side, 11c coated side, 11d second uncoated side, 11e 11f flatness reinforcement layer, 12 separator, 13 second electrode plate, 13a first uncoated side, 13b coated side, 13c single uncoated side, 13d second uncoated side, 13e 13f flatness reinforcement layer, 14 first electrode tab, 15 second electrode tab, 16 first strip conductor, 17 second strip conductor, 20 pouch, 21 sealing part, 38 59 case, 50 60 cap assembly
Claims
Claim 1 A secondary battery comprising: an electrode assembly including an electrode plate including an electrode tab attached to an electrode plate substrate; and an outer material in which the electrode assembly is housed, wherein the electrode plate of the electrode assembly further comprises a first flatness reinforcing layer applied to a stepped portion between the surface of the electrode tab and the surface of the electrode plate substrate. Claim 2 A secondary battery according to claim 1, wherein the first flatness reinforcing layer comprises a lower flatness reinforcing layer applied to the lower part of the electrode tab. Claim 3 A secondary battery according to claim 1, wherein the first flatness reinforcing layer comprises a side flatness reinforcing layer applied to the side of the electrode tab. Claim 4 A secondary battery according to one of claims 1 to 3, wherein the first flatness reinforcing layer comprises an insulating material applied to the electrode plate substrate. Claim 5 A secondary battery according to one of claims 1 to 3, wherein the first flatness reinforcing layer comprises an insulating tape attached to the electrode plate substrate. Claim 6 A secondary battery according to claim 1, wherein the electrode plate of the electrode assembly further comprises a lamination tape attached to the electrode plate substrate and a second flatness reinforcing layer applied to a stepped portion between the surface of the lamination tape and the surface of the electrode plate substrate. Claim 7 In claim 6, the second flatness reinforcing layer comprises an insulating material applied to the electrode plate substrate, in a secondary battery. Claim 8 A secondary battery according to claim 6, wherein the second flatness reinforcing layer comprises an insulating tape attached to the electrode plate substrate. Claim 9 In claim 1, the above-mentioned exterior material is an exterior pouch for a pouch battery, a secondary battery. Claim 10 In paragraph 1, the above-mentioned outer material is an outer can for a cylindrical or prismatic battery, a secondary battery. Claim 11 A method for manufacturing a secondary battery comprising: a step of producing an electrode plate by coating an electrode material onto a substrate; a step of welding an electrode tab to the substrate of the produced electrode plate; a step of applying a first flatness reinforcement layer to a stepped portion caused by a height difference between the surface of the electrode tab and the surface of the substrate; a step of producing an electrode assembly by winding the electrode plate to which the flatness reinforcement layer is applied; and a step of housing the electrode assembly in a secondary battery casing. Claim 12 A method for manufacturing a secondary battery according to claim 11, wherein the step of applying the first flatness reinforcing layer comprises applying the first flatness reinforcing layer to the lower part of the electrode tab. Claim 13 A method for manufacturing a secondary battery according to claim 11, wherein the step of applying the first flatness reinforcing layer comprises applying the first flatness reinforcing layer to the side of the electrode tab. Claim 14 A method for manufacturing a secondary battery, wherein, in any one of claims 11 to 13, the step of applying the first flatness reinforcing layer comprises applying an insulating material to the electrode plate substrate. Claim 15 A method for manufacturing a secondary battery, wherein in one of claims 11 to 13, the step of applying the first flatness reinforcing layer comprises attaching an insulating tape to the electrode plate substrate. Claim 16 A method for manufacturing a secondary battery according to claim 11, wherein the step of manufacturing the electrode plate further comprises attaching a lamination tape to the electrode plate substrate and further comprising applying a second flatness reinforcing layer to the stepped portion between the surface of the attached lamination tape and the surface of the electrode plate substrate. Claim 17 A method for manufacturing a secondary battery according to claim 16, wherein the step of applying the second flatness reinforcing layer comprises applying an insulating material to the electrode plate substrate. Claim 18 A method for manufacturing a secondary battery according to claim 16, wherein the step of applying the second flatness reinforcement layer comprises attaching an insulating tape to the electrode plate substrate. Claim 19 A method for manufacturing a secondary battery according to claim 11, wherein the step of accommodating the electrode assembly in a secondary battery outer material includes accommodating the electrode assembly in an outer pouch for a pouch battery. Claim 20 A method for manufacturing a secondary battery according to claim 11, wherein the step of accommodating the electrode assembly in a secondary battery outer casing includes accommodating the electrode assembly in an outer can for a cylindrical or prismatic battery.