Electrode assembly and method for manufacturing electrode assembly

Abstract

The present disclosure relates to an electrode assembly and a method for manufacturing the electrode assembly. An electrode assembly according to the present disclosure may comprise: a jelly roll in which a first electrode, a separator, and a second electrode are sequentially stacked and wound; and a finishing tape attached to surround the outer surface of the jelly roll at least once, wherein the finishing tape comprises an overlapping portion formed by at least partially overlapping one end and the other end of the finishing tape in the winding direction of the jelly roll.

Description

Electrode assembly and method for manufacturing electrode assembly

[0001] The present disclosure relates to an electrode assembly and a method for manufacturing the electrode assembly.

[0002]

[0003] Secondary batteries, unlike non-rechargeable primary batteries, are rechargeable and dischargeable. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for motor drives and power storage in hybrid and electric vehicles. These secondary batteries include an electrode assembly comprising a positive and negative electrode, a case housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0004] Secondary batteries are used in a variety of environments due to their excellent electrical properties. However, during the charging and discharging process, ions move within the battery, transferring electrical energy. This change in chemical energy causes the volume of the battery's jelly roll to increase or decrease. This repeated shrinkage and expansion during the charging and discharging process imposes uneven mechanical stress on the battery's interior, shortening its lifespan and leading to reduced battery performance through structural damage.

[0005] In particular, as the size of a battery (e.g., a cylindrical battery) manufactured by winding an electrode assembly increases, the tension on the side increases due to shrinkage and expansion of the jelly roll during the charging and discharging process after cell assembly, and as a result, the outer diameter of the central part in particular increases significantly or cracks occur on the side of the battery due to stretching.

[0006]

[0007] The problem to be solved by the present invention is to provide an electrode assembly and a battery including the same for solving the above technical problem.

[0008] 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.

[0009]

[0010] An electrode assembly of a secondary battery according to one embodiment of the present invention for solving a technical problem includes a jelly roll in which a first electrode, a separator, and a second electrode are sequentially laminated and wound, and a finishing tape attached so as to wrap the outer surface of the jelly roll at least once, and the finishing tape may include an overlapping portion formed by overlapping at least a portion of one end and the other end of the finishing tape in the winding direction of the jelly roll.

[0011] In one embodiment, the length of the finishing tape may be 100% to 300% of the circumferential length of the jelly roll.

[0012] In one embodiment, the length of the overlapping portion may be from 20 mm to 50 mm.

[0013] In one embodiment, the width of the finishing tape may be from 40% to 100% of the width of the jelly roll.

[0014] In one embodiment, the center of the width of the finishing tape may be the same as the center of the width of the jelly roll.

[0015] In one embodiment, the thickness of the finishing tape may be from 20 μm to 100 μm.

[0016] In one embodiment, the elongation of the finishing tape may be from 101% to 110%.

[0017] In one embodiment, the finishing tape may include a substrate layer and an adhesive layer applied to a portion of the substrate layer.

[0018] In one embodiment, the adhesive layer may be applied across the entire end edge of one side of the substrate layer.

[0019] In one embodiment, the closing tape may comprise polypropylene (PP).

[0020] In one embodiment, the closing tape may comprise polyethylene terephthalate (PET).

[0021] In one embodiment, the finishing tape may include PI (Polyimide).

[0022] In one embodiment, the finishing tape may comprise nitrile butadiene rubber (SBR).

[0023] In one embodiment, the finishing tape may include styrene butadiene rubber (SBR).

[0024] According to one embodiment, the finishing tape may include a central portion and an outer portion, and the thickness of the finishing tape may increase from the outer portion to the central portion.

[0025] In one embodiment, the diameter of the jelly roll may be from 40 mm to 50 mm.

[0026] A secondary battery according to one embodiment of the present invention includes an electrode assembly including a jelly roll in which a first electrode, a separator, and a second electrode are sequentially stacked and wound, a case in which the electrode assembly is accommodated, and a finishing tape attached so as to wrap the outer surface of the jelly roll at least once, wherein the finishing tape may include an overlapping portion formed by overlapping at least a portion of one end and the other end of the finishing tape in the winding direction of the jelly roll.

[0027] In one embodiment, the case may have a diameter of 41 mm to 51 mm.

[0028] According to one embodiment, the method may include a step of sequentially stacking and winding a first electrode, a separator, and a second electrode to produce a jelly roll, and a step of wrapping the outer surface of the jelly roll with a finishing tape at least once.

[0029] According to one embodiment, the step of wrapping the outer surface of the jelly roll with the finishing tape at least once may include the step of wrapping the outer surface of the jelly roll with the finishing tape such that at least a portion of one end and the other end of the finishing tape overlap in the winding direction of the jelly roll, thereby forming an overlapping portion.

[0030]

[0031] According to some embodiments of the present disclosure, the expansion suppression effect of the jelly roll can be maximized by overlapping the finishing tapes that wrap the exterior of the jelly roll constituting the electrode assembly of the secondary battery.

[0032] According to some embodiments of the present disclosure, when the length of the finishing tape wrapping the jelly roll of the electrode assembly is 200% or more of the circumferential length of the jelly roll, the suppression of jelly roll expansion due to charging and discharging of the secondary battery can be further strengthened.

[0033] According to some embodiments of the present disclosure, a finishing tape is placed in a central portion where cracks or tears are continuously found during the charging and discharging process of a secondary battery, thereby preventing cracks from occurring in advance and improving the durability and lifespan of the electrode assembly.

[0034] According to some embodiments of the present disclosure, it is possible to increase the power efficiency per weight of a secondary battery while suppressing an increase in the outer diameter of a central electrode assembly that causes defects in the secondary battery, without increasing the side thickness of the case of the secondary battery having a high density.

[0035] 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.

[0036]

[0037] 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.

[0038] FIG. 1 is a side view of an electrode assembly according to one embodiment of the present disclosure.

[0039] FIG. 2 is a schematic drawing of an electrode assembly including a finishing tape according to one embodiment of the present disclosure.

[0040] FIG. 3 is a plan view showing a cross-section of an electrode assembly according to one embodiment of the present disclosure.

[0041] FIG. 4 is a perspective view showing an electrode assembly according to one embodiment of the present disclosure.

[0042] FIG. 5 is a plan view showing a cross-section of an electrode assembly according to one embodiment of the present disclosure.

[0043] FIG. 6 is an exploded perspective view of an electrode assembly and a case of a secondary battery including the same according to one embodiment of the present disclosure.

[0044] Figure 7 is a cross-sectional view of a secondary battery according to one embodiment of the present disclosure.

[0045] Figure 8 is a flowchart illustrating an example of a method for manufacturing an electrode assembly according to the present disclosure.

[0046]

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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 also mean uniformity on average.

[0051] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0052] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0053] Any configuration being arranged "on the top (or bottom)" of a component or "on the upper (or lower) side" of a component may mean not only that any configuration is arranged in contact with the upper surface (or lower surface) of the component, but also that another configuration may be interposed between the component and any configuration arranged on (or under) the component. In addition, in the drawings, the portion between the upper and lower portions of the components depicted or the remaining portion excluding the upper and lower portions may be referred to as a "side" or a "side surface." Additionally, the direction toward the internal space of the component may be referred to as "inner," and the direction protruding into the open external space may be referred to as "outer." Relative terms such as "upper," "top," etc. may be used to describe the relationship between the configurations depicted in the drawings, and the present disclosure is not limited by such terms.

[0054] For ease of description, spatially relative terms such as "beneath," "below," "lower," "above," "upper," and the like may be used herein to describe the relationship of one element or feature to another element(s) or feature(s) as depicted in the drawings. It will be understood that spatially relative positions encompass 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 drawings is turned over, an element described as "beneath" or "lower" another element would be understood to be "above" or "upper" the other element. Thus, the term "beneath" can encompass both the above and below orientations.

[0055] Additionally, when a component is described as being "on," "connected to," or "coupled to" another component, it should be understood that the components may be directly connected or coupled to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through other components.

[0056] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Furthermore, the use of "may" when describing embodiments of the present disclosure refers to "one or more embodiments of the present disclosure." The use of phrases such as "one or more" before a list of elements modifies the list as a whole and does not modify individual elements in the list.

[0057] When reference is made throughout the specification to “A and / or B,” this means A, B, or A and B, unless otherwise stated, and when reference is made to “C through D,” this means C or more and D or less, unless otherwise stated.

[0058] Although terms such as first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, 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. Thus, a first element, component, region, layer, or section discussed below could also be termed a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0059] 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.

[0060] FIG. 1 is a side view of an electrode assembly according to one embodiment of the present disclosure.

[0061] Referring to FIG. 1, an electrode assembly (100) of a secondary battery according to one embodiment of the present invention may include a jelly roll (110) in which a first electrode, a separator (separation film), and a second electrode are sequentially laminated and wound, and a finishing tape (120) attached so as to wrap the outer surface (112) of the jelly roll (110) at least once.

[0062] The first electrode may be an electrode corresponding to the positive or negative electrode in a secondary battery. The second electrode may be an electrode corresponding to the opposite pole to the first electrode. For example, if the first electrode is the positive electrode, the second electrode may be the negative electrode. Conversely, if the first electrode is the negative electrode, the second electrode may be the positive electrode.

[0063] The outer surface (112) of the jelly roll (110) may include a separator or a substrate layer constituting the first electrode, which is arranged at the outermost or the bottommost when the jelly roll (110) is stacked. Specifically, the outer surface (112) of the jelly roll (110) may be one end of a separator that is extended from the separator to prevent the active material constituting the first electrode or the second electrode from being exposed to the outside. In another example, the outer surface (112) of the jelly roll (110) may be one end of a substrate layer formed by extending a non-coated portion of the substrate layer on which the active material constituting the first electrode or the second electrode is not applied.

[0064] The finishing tape (120) may include an overlapping portion (122) formed by overlapping at least a portion of one end and the other end of the finishing tape (120) in the winding direction of the jelly roll (110). That is, with reference to FIG. 1, one end of the finishing tape (120) may be fixed to the outer surface (112) of the jelly roll (110) and overlap the other end of the finishing tape (120) in the transverse direction in which the jelly roll (110) is wound, thereby forming the overlapping portion (122). Here, it is sufficient that one end and the other end of the finishing tape (120) overlap in the winding direction of the jelly roll (110), that is, in the transverse direction with reference to FIG. 1, and the winding direction of the finishing tape (120) does not necessarily have to be the same as the winding direction of the jelly roll (110). For example, the winding direction of the finishing tape (120) may be in the opposite direction parallel to the winding direction of the jelly roll (110).

[0065] According to one embodiment, the length of the overlapping portion (122) may be 20 mm to 50 mm. Specifically, the shortest distance between the outer periphery of one end of the finishing tape (120) and the outer periphery of the other end of the finishing tape (120) in the overlapping portion (122) may be 20 mm to 50 mm. According to one embodiment, the outer periphery of one end of the finishing tape (120) and the outer periphery of the other end of the finishing tape (120) are parallel to each other, so that the shape of the overlapping portion (122) when viewed from the side may be a rectangular shape, as illustrated in FIG. 1. Accordingly, the length of the horizontal side of the rectangle forming the overlapping portion (122) may be 20 mm to 50 mm.

[0066] According to one embodiment, the length of the closing tape (120) may be 100% to 300% of the circumference of the jelly roll (110). In addition, since the closing tape (120) is adhered to the outer surface (112) of the jelly roll (110) without any gaps, the length of the overlapping portion (122) may be determined according to the length of the closing tape (120). For example, when the length of the closing tape (120) is 200% or more of the circumference of the jelly roll (110), the length of the overlapping portion (122) may be greater than or equal to the circumference of the jelly roll (110).

[0067] According to some embodiments of the present disclosure, the expansion suppression effect of the jelly roll can be maximized by overlapping the finishing tapes that wrap the exterior of the jelly roll.

[0068] In particular, according to some embodiments of the present disclosure, when the length of the closing tape (120) is 200% or more of the circumferential length of the jelly roll (110), the suppression of the jelly roll (110) from expansion due to charging and discharging of the secondary battery can be further strengthened.

[0069] FIG. 2 is a schematic drawing of an electrode assembly (200) including a finishing tape according to one embodiment of the present disclosure.

[0070] Referring to FIG. 2, an electrode assembly (200) according to one embodiment of the present invention may include a jelly roll (210) in which a first electrode (213), a separator (214), and a second electrode (215) are sequentially stacked and wound, and a finishing tape (220) attached so as to wrap the outer surface (212) of the jelly roll (210) at least once.

[0071] According to one embodiment, the finishing tape (220) may include a substrate layer (224) and an adhesive layer (226) applied to a portion of the substrate layer (224).

[0072] The substrate layer (224) is preferably formed of a polymer material including rubber or plastic to have elasticity. That is, the finishing tape (220) including the substrate layer (224) can suppress expansion due to stress caused by elasticity when the jelly roll (210) expands due to the movement of electrons during charging / discharging of the secondary battery. For example, the substrate layer (224) may include PP (Polypropylene), PET (Polyethylene terephthalate), PI (Polyimide), Nitrile Butadiene Rubber (SBR), Styrene Butadiene Rubber (SBR), or a combination thereof.

[0073] In one embodiment, the substrate layer (224) may be woven from fibers such as aramid fibers and Nomex. A fabric woven from fibers can effectively suppress expansion due to tension between fibers when the jelly roll (210) expands. In another embodiment, the substrate layer (224) may include a ceramic insulator made of alumina (Al2O3), zirconia (ZrO2), epoxy resin, or a combination thereof. However, the substrate layer (224) of the finishing tape (220) is not limited to the above materials, and may include various materials with excellent durability and electrical insulation properties according to the selection of a person skilled in the art.

[0074] In addition, the substrate layer (224) may be formed of a material having a softening point of 150°C or higher so as not to be deformed by the temperature generated during charging / discharging of the secondary battery.

[0075] In one embodiment, the adhesive layer (226) may be applied to the entire end edge of one side of the substrate layer (224), as illustrated in FIG. 2. Specifically, the adhesive layer (226) may be applied on the inner side forming the overlapping portion (222) at the end edge of one side of the substrate layer (224). In another example, the adhesive layer (226) may be applied to the entire end surface of one side of the substrate layer (224). Specifically, the adhesive layer (226) may be applied on the inner side of the substrate layer (224) that contacts the outer surface (212) of the jelly roll (210).

[0076] According to one embodiment, the adhesive layer (226) may correspond to the size of the overlapping portion (222). Specifically, the width of the adhesive layer (226) may have the same size as the width of the overlapping portion (222).

[0077] The adhesive layer (226) may include any one of a polymer adhesive including acrylic or rubber, a liquid adhesive, a double-sided tape, or a combination thereof. The adhesive layer (226) is not limited to the above materials, and may include various materials with excellent adhesive properties and electrical insulation properties, depending on the selection of a person skilled in the art.

[0078] According to one embodiment, the closing tape (220) may further include a fixing layer (not shown). The fixing layer may be additionally applied to at least a portion of the inner side of the substrate layer (224) that comes into contact with the outer surface (212) of the jelly roll (210) to fix the closing tape (220) on the outer surface (212) of the jelly roll (210). The fixing layer may be composed of the same material as the adhesive layer (226).

[0079] FIG. 3 is a plan view showing a cross-section of an electrode assembly according to one embodiment of the present disclosure.

[0080] Referring to FIG. 3, in one embodiment, the thickness (329) of the finishing tape (320) wrapping the outer surface of the jelly roll (310) may be 20 μm to 100 μm. The thickness (329) of the finishing tape (320) may be changed according to the purpose and the selection of a person skilled in the art. If the thickness (329) of the finishing tape (320) is too thin, it may be difficult for the jelly roll (310) expansion suppressing effect of the finishing tape (320) to be exerted, and conversely, if the thickness (329) is too thick, the thickness of the overlapping portion (322) increases accordingly, which may cause significant damage to the electrode assembly when inserted into the secondary battery case or may cause a decrease in capacity in the same standard size.

[0081] According to one embodiment, the elongation of the closing tape (320) may be 101% to 110%. The elongation of the closing tape (320) may be changed according to the purpose and the selection of a person skilled in the art. If the elongation of the closing tape (320) is greater than 110%, stress may be concentrated due to excessive deformation, which may easily cause breakage of the secondary battery case. If the elongation of the closing tape (320) is less than 101%, it may react sensitively to external impact or force, which may easily cause deformation or damage to the closing tape (320) itself.

[0082] FIG. 4 is a perspective view showing an electrode assembly according to one embodiment of the present disclosure.

[0083] Referring to FIG. 4, the width (429) of the closing tape (420) may be 40% to 100% of the width (419) of the jelly roll (410). The width (429) of the closing tape (420) may be changed according to the purpose and the selection of a person skilled in the art. If the width (429) of the closing tape (420) is too small, it may be difficult for the jelly roll (410) expansion suppression effect of the closing tape (420) to be exerted, and conversely, if the width (429) is too large than the width (419) of the jelly roll (410), it may occupy the internal space of the secondary battery case, which may result in a decrease in capacity in the same standard size.

[0084] The center of the width (429) of the finishing tape (420) may be located at various locations according to the selection of a person skilled in the art, as long as one end of the width (429) of the finishing tape (420) does not exceed the width (419) of the jelly roll (410). For example, when the width (429) of the finishing tape (420) is 50% of the width (419) of the jelly roll (410), the center of the width (429) of the finishing tape (420) may be located at a distance within 25% of the width (419) of the jelly roll (410) from the center of the width (419) of the jelly roll (410). Preferably, the center of the width (429) of the finishing tape (420) may be the same as the center of the width (419) of the jelly roll (410). This will be described later in FIG. 5.

[0085] FIG. 5 is a plan view showing a cross-section of an electrode assembly according to one embodiment of the present disclosure.

[0086] Referring to FIG. 5, the center (521) of the width of the finishing tape (520) may be the same as the center (511) of the width of the jelly roll (510). Specifically, since the center of the jelly roll (510) receives a higher stress than the outer edge in the cross-section of the electrode assembly formed as the jelly roll (510) is wound, by separately arranging the finishing tape (520) with respect to the center (511) of the width of the jelly roll (510), expansion of the jelly roll (510) due to charging and discharging of the secondary battery can be prevented.

[0087] In secondary batteries, particularly lithium-ion batteries, the charging and discharging processes occur through the movement of lithium ions between the electrolyte and electrodes. During this process, the electrode assembly undergoes physical volume changes as it absorbs or releases lithium ions. This shrinkage and expansion can cause problems that significantly impact the battery's lifespan and performance. For example, in an electrode assembly wound and inserted into a secondary battery case, the electrodes located on the periphery may experience uneven mechanical stress due to the shrinkage and expansion of the electrode assembly.

[0088] In particular, electrodes located in the central portion of the side face can be observed to elongate and crack as tension increases with expansion. These cracks can eventually lead to internal short circuits or delamination, which can degrade battery performance or shorten its lifespan, significantly reducing the battery's safety and reliability.

[0089] According to one embodiment, the finishing tape (520) includes a central portion (527) and an outer portion (528), and the thickness of the finishing tape (520) may become thicker from the outer portion (528) to the central portion (527). In FIG. 5, the outline connecting the central portion (527) and the outer portion (528) is expressed to have a constant curvature, but is not limited thereto, and the outline connecting the central portion (527) and the outer portion (528) may include a straight line. Through this configuration, by making the thicknesses of the central portion (527) and the outer portion (528) of the finishing tape (520) different, the internal space of the secondary battery case is reduced, and at the same time, the center of the jelly roll (510) where expansion occurs is effectively protected, thereby effectively preventing cracks from occurring in the electrode assembly.

[0090] FIG. 6 is an exploded perspective view of an electrode assembly and a case of a secondary battery including the same according to one embodiment of the present disclosure.

[0091] A secondary battery according to one embodiment of the present invention may include an electrode assembly including a jelly roll (610) in which a first electrode, a separator, and a second electrode are sequentially stacked and wound, a case (630) in which the electrode assembly is housed, and a finishing tape (620) attached so as to wrap around the outer surface of the jelly roll (610) at least once. In addition, the finishing tape (620) may include an overlapping portion formed by overlapping at least a portion of one end and the other end of the finishing tape (620) in the winding direction of the jelly roll (610).

[0092] The first electrode, separator and second electrode may be impregnated with an electrolyte (not shown).

[0093] The case (630) forms the overall appearance of the secondary battery and may be formed of a conductive metal such as aluminum, aluminum alloy, stainless steel (e.g., SUS), or nickel-plated steel, or a polymer. In addition, the case (630) may provide a space in which an electrode assembly including a jelly roll (610) and a finishing tape (620) is accommodated. For the purpose of explaining the invention, the case (630) is illustrated in FIG. 6 as a cylindrical battery, but the scope of the present disclosure is not limited thereto and includes secondary batteries of any shape, such as square batteries and pouch batteries.

[0094] In one embodiment, when the jelly roll (610) is rolled into a cylindrical shape, the diameter of the jelly roll (610) may be 40 mm to 50 mm. In addition, the case (630) may have a shape corresponding thereto to accommodate the jelly roll (610). In one embodiment, when the jelly roll (610) is rolled into a cylindrical shape, the case (630) may have a cylindrical shape. In addition, the case (630) may have a diameter larger than the jelly roll (610) to accommodate the jelly roll (610). For example, the diameter of the case (630) may be 41 mm to 51 mm.

[0095] According to some embodiments of the present disclosure, a finishing tape is placed in a central portion where cracks or tears are continuously found during the charging and discharging process of a secondary battery, thereby preventing cracks from occurring in advance and improving the durability and lifespan of the electrode assembly.

[0096] FIG. 7 is a cross-sectional view of a secondary battery according to an embodiment of the present disclosure. Referring to FIG. 7, the secondary battery according to an embodiment of the present disclosure includes an electrode assembly (710) that performs charging and discharging, a case (720) housing the electrode assembly (710), a first current collector (730) connected to the electrode assembly (710), a second current collector (750), an electrode terminal (741), a vent cap plate (742), and a gasket (760). In FIG. 7, the vent cap plate (742) is illustrated as being disposed on the upper side of the secondary battery, and the electrode terminal (741) is disposed on the lower side of the secondary battery, but this is not limited thereto. Depending on the usage environment or requirements of the secondary battery, the vent cap plate (742) and the electrode terminal (741) may be changed to be disposed on the lower side and the upper side of the secondary battery, respectively.

[0097] An electrode assembly (710) is formed by winding a first electrode (711a, 711b), a separator (713), and a second electrode (712a, 712b) into a cylindrical jelly roll state with an empty core. The first electrode (711a, 711b) and the second electrode (712a, 712b) each include a coated portion (711a, 712a) in which an active material is applied to both sides of a substrate formed of a thin metal plate, and a non-coated portion (711b, 712b) in which the substrate is exposed because the active material is not applied.

[0098] The first electrode (711a, 711b) may be an electrode corresponding to a positive or negative electrode in a secondary battery. The second electrode (712a, 712b) may be an electrode corresponding to a pole opposite to the first electrode (711a, 711b). For example, if the first electrode (711a, 711b) is a positive electrode, the second electrode (712a, 712b) may be a negative electrode. Conversely, if the first electrode (711a, 711b) is a negative electrode, the second electrode (712a, 712b) may be a positive electrode.

[0099] For example, the first electrode (711a, 711b) may form a positive electrode by coating a positive electrode active material on an aluminum (Al) substrate, and the second electrode (712a, 712b) may form a negative electrode by coating a negative electrode active material on a copper (Cu) substrate. The non-coated portion (711b) of the first electrode and the non-coated portion (712b) of the second electrode are respectively provided at opposite ends of the electrode assembly (710) in the winding axis direction, but electrode terminals (741) and cases (720) having different polarities in the same direction are provided together. A vent cap plate (742) is positioned on the opposite side of the electrode terminal (741).

[0100] The case (720) is formed in a cylindrical shape to house the electrode assembly (710), and the electrode terminal (741) and the vent cap plate (742) are provided at each of the axial ends of the case (720) so as to face each other.

[0101] The electrode terminal (741) is connected to the first electrode (711a, 711b) through the first collector plate (730) via a rivet (743), and the case (720) is connected to the second electrode (712a, 712b) through the second collector plate (750). At this time, the vent cap plate (742) is electrically separated from the second collector plate (750) and the case (720) and has no polarity.

[0102] An electrode terminal (741) connected to a first electrode (711a, 711b) of an electrode assembly (710) inserted into a case (720) from the outside is installed on one side of the case. The case (720) has a partially open through hole (721) on one side.

[0103] For example, the electrode terminal (741) may be installed in a rivet structure in the through hole (721) of the case (720). For this purpose, the electrode terminal (741) may be connected to a rivet (743). One end of the rivet (743) is welded to the first collector plate (730) and is positioned to penetrate the through hole (721). The electrode terminal (741) is connected to the rivet (743) and is positioned on the outside of the case (720). The electrode terminal (741) may be formed to protrude beyond the outer surface of the case (720) around the through hole (721) and may be used as a positive electrode terminal. At this time, the first collector plate (730) becomes a positive electrode collector plate.

[0104] At this time, the first collector plate (730) is electrically connected to the uncoated portion (711b) of the first electrode through a rivet (743) and is electrically and mechanically connected to the electrode terminal (741). The first collector plate (730) is electrically connected to the electrode terminal (741) in a structure that reduces resistance by contacting most of the uncoated portion (711b) of the first electrode. The rivet (743) included in the electrode terminal (741) is installed in a state of electrical insulation from the case (720) while forming a gas-tight structure with respect to the electrolyte by interposing an insulator (723) in the through hole (721).

[0105] Here, the insulator (723) may be made of a polymer including ethylene propylene rubber (EPDM), polypropylene (PP), polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), or a combination thereof.

[0106] As another example, the insulator (723) may be made of a ceramic material including epoxy resin, alumina (Al2O3), zirconia (ZrO2), aramid fiber, Nomex, or a combination thereof. However, the material of the insulator (723) is not limited to the materials listed above, and may include various materials with excellent plasticity and insulation properties depending on the selection.

[0107] In one embodiment, the first collector plate (730) may include a metal plate (731) including at least one bridge (732). For example, the first collector plate (730) may be formed of a conductive metal, specifically, a conductive metal such as nickel, aluminum, copper, silver, zinc, tin, stainless steel (e.g., SUS), nickel-plated steel, or a combination (alloy) thereof. In addition, the metal plate (731) and the bridge (732) constituting the first collector plate (730) may be made of the same material to form an integral body.

[0108] Here, the bridge (732) of the first collector plate (730) may be configured to be ruptured when a current exceeding a set value flows. For example, the bridge (732) normally operates as a part of a circuit through which current flows, but when an excessive amount of current flows, it may function as a fuse that melts due to the generated heat and blocks the circuit.

[0109] An insulating tape (745) may be attached to one side of the first collector plate (730). The insulating tape (745) may be interposed between the first collector plate (730) and the case (720) or between the non-conductive portion (711b) of the first electrode and the case (720), and may serve to electrically insulate each component. In one embodiment, the central portion of the insulating tape (745) may include a perforation (746) corresponding to the shape of the rivet (743) so that the rivet (743) may come into contact with the first collector plate (730). In addition, the insulating tape (745) may include a side wall (747) so as to surround a portion of the electrode assembly (710).

[0110] Additionally, the case (720) has a fully open opening (722) to allow the electrode assembly (710) to be inserted into the other side. The vent cap plate (742) seals the opening (722) after the electrode assembly (710) is inserted into the case (720) and is electrically isolated from the case (720).

[0111] At this time, the second collector plate (750) is electrically connected to the non-conductive portion (712b) of the second electrode and is electrically connected to the case (720). The second collector plate (750) is connected to the case (720) in a structure that reduces resistance by contacting most of the non-conductive portion (712b) of the second electrode.

[0112] The second collector plate (750) includes a bottom portion (751) welded to the non-conductive portion (712b) of the second electrode, and wing portions (752) formed adjacent to the bottom portion (751) and welded to the beading portion (729). The second collector plate (750) is formed by cutting and bending a circular plate, and each of the bottom portions (751) and wing portions (752) is provided in multiple numbers and arranged alternately along the circumferential direction. In one embodiment, the wing portions (752) can be repeatedly formed by bending the axial direction (upward) and radial direction (outer) of the electrode assembly (710).

[0113] In one embodiment, when the non-coated portion (712b) of the second electrode and the bottom portion (751) of the second collector plate (750) are welded, the bottom portion (751) can form a welding line in the diameter direction of the second collector plate (750). Accordingly, the bottom portion (751) can be evenly connected along the circumferential direction in the area of ​​the non-coated portion (712b) of the second electrode, and the wing portion (752) can be evenly connected along the circumferential direction in the area of ​​the beaded portion (729). This can enable a uniform current flow along the circumferential direction in the entire area of ​​the beaded portion (729) of the case (720) from the non-coated portion (712b) of the second electrode.

[0114] In addition, since the second collector plate (750) has a hole (753) in the center, it can absorb and alleviate deformation caused by welding of the bottom portion (751) and the non-conductive portion (712b) of the second electrode, as well as vibration and shock that may be transmitted between the wing portion (752) and the bottom portion (751). The hole (753) can have a size that can absorb vibration and shock without increasing the current resistance between the wing portion (752) and the bottom portion (751).

[0115] The vent cap plate (742) is electrically isolated from the second collector plate (750) and is installed in the opening (722) of the case (720) through a crimping process. Alternatively, the vent cap plate (742) is installed in the opening (722) of the case (720) through a welding process. Due to the connection of the second collector plate (750), the case (720) can be used as a negative terminal. In this case, the second collector plate (750) becomes a negative collector plate.

[0116] The vent cap plate (742) may form a notch (744) on its inner surface. The notch (744) may be cut open to release internal pressure of the secondary battery to the outside when an abnormal event occurs in the secondary battery, thereby preventing a secondary explosion. Specifically, the notch (744) may be easily cut open by intensively receiving internal pressure in the event of an abnormal event. The notch (744) may be formed over the entire circumferential area of ​​the vent plate (742), or may be formed in multiple pieces spaced apart at set intervals.

[0117] A gasket (760) is interposed between the second collector plate (750) and the vent cap plate (742) and between the second collector plate (730) and the case (720) to seal the case by means of a beading portion (729) or a clamping process. In addition, the gasket (760) can form a gastight structure with respect to the electrolyte between the second collector plate (730) and the opening (722) of the case (720).

[0118] For example, the gasket (760) may include a polymer material or ceramic such as polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE or Teflon), polyethylene (PE), epoxy resin, silicone, polyvinylidene fluoride (PVDF), polypropylene (PP), polyacrylonitrile (PAN), or polyethylene oxide (PEO), but is not limited thereto, and may correspond to any one of the appropriate compounds used as an insulating material in the art.

[0119] The finishing tape (790) may be attached to wrap the outer surface of the jelly roll of the electrode assembly (710) at least once. Here, the finishing tape (790) may have at least one configuration or function among the finishing tapes (120, 220, 320, 420, 520, 620) described with reference to FIGS. 1 to 6. In addition, the electrode assembly (710) may be inserted into the case (720) with the finishing tape (790) attached, and the finishing tape (790) may be positioned between the electrode assembly (710) and the case (720). Accordingly, the assembled secondary battery prevents the electrode assembly (710) from moving up and down or forward and backward inside the case (720), thereby preventing separation of terminals or damage to components, and can suppress cracks in the case (720) or electrode assembly (710) due to excessive expansion of the electrode assembly (710) even when the electrode assembly (710) expands due to charging and discharging.

[0120] A secondary battery according to one embodiment of the present invention can be applied to automobiles, mobile phones, and / or various types of electrical devices, and the present invention is not limited thereto.

[0121] Figure 8 is a flowchart illustrating an example of a method for manufacturing an electrode assembly according to the present disclosure.

[0122] A method for manufacturing an electrode assembly (800) according to one embodiment may be initiated by sequentially stacking and winding a first electrode, a separator, and a second electrode to produce a jelly roll (S810). Here, the diameter of the jelly roll may be 40 mm to 50 mm.

[0123] Afterwards, the outer surface of the jelly roll can be wrapped at least once with a finishing tape and attached (S820). The length of the finishing tape may be 100% to 300% of the circumference of the jelly roll, the width of the finishing tape may be 40% to 100% of the width of the jelly roll, and the thickness of the finishing tape may be 20 μm to 100 μm. In addition, the finishing tape may include a central portion and an outer portion, and the thickness of the finishing tape may become thicker from the outer portion to the central portion.

[0124] In one embodiment, the finishing tape may include a substrate layer and an adhesive layer applied to a portion of the substrate layer, and the adhesive layer may be applied to the entire end edge of one side of the substrate layer. The substrate layer may include polypropylene (PP), polyethylene terephthalate (PET), polyimide (PI), nitrile butadiene rubber (SBR), styrene butadiene rubber (SBR), or a combination thereof.

[0125] In one embodiment, the step of wrapping the outer surface of the jelly roll with the finishing tape at least once may include the step of wrapping the outer surface of the jelly roll with the finishing tape such that at least a portion of one end and the other end of the finishing tape overlap in the winding direction of the jelly roll, thereby forming an overlapping portion. Here, the length of the overlapping portion may be 20 mm to 50 mm.

[0126] According to some embodiments of the present disclosure, it is possible to increase the power efficiency per weight of a secondary battery while suppressing an increase in the outer diameter of a central electrode assembly that causes defects in the secondary battery, without increasing the side thickness of the case of the secondary battery having a high density.

[0127] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various modifications and variations can be made by those skilled in the art within the scope of the technical idea of ​​the present invention and the equivalent scope of the claims to be described below. Those skilled in the art can make various substitutions, variations, and changes without departing from the technical idea of ​​the present invention, and therefore the present invention is not limited by the above-described embodiments and the attached drawings.

Claims

1. A jelly roll in which a first electrode, a separator, and a second electrode are sequentially laminated and wound; and Including a finishing tape attached to wrap the outer surface of the jelly roll at least once, An electrode assembly of a secondary battery, wherein the above-mentioned finishing tape includes an overlapping portion formed by overlapping at least a portion of one end and the other end of the finishing tape in the winding direction of the jelly roll.

2. In paragraph 1, An electrode assembly wherein the length of the above-mentioned finishing tape is 100% to 300% of the circumferential length of the above-mentioned jelly roll.

3. In paragraph 1, An electrode assembly wherein the length of the above-mentioned overlapping portion is 20 mm to 50 mm.

4. In paragraph 1, An electrode assembly wherein the width of the above finishing tape is 40% to 100% of the width of the above jelly roll.

5. In paragraph 1, An electrode assembly wherein the center of the width of the above finishing tape is the same as the center of the width of the above jelly roll.

6. In paragraph 1, An electrode assembly wherein the thickness of the above finishing tape is 20 μm to 100 μm.

7. In paragraph 1, An electrode assembly wherein the elongation of the above finishing tape is 101% to 110%.

8. In paragraph 1, An electrode assembly, wherein the above finishing tape includes a substrate layer and an adhesive layer applied to a portion of the substrate layer.

9. In paragraph 8, An electrode assembly, wherein the adhesive layer is applied to the entire edge of one end of the substrate layer.

10. In paragraph 1, The above finishing tape is an electrode assembly containing PP (Polypropylene).

11. In paragraph 1, The above finishing tape is an electrode assembly containing PET (Polyethylene terephthalate).

12. In paragraph 1, The above finishing tape is an electrode assembly containing PI (Polyimide).

13. In paragraph 1, The above finishing tape is an electrode assembly comprising nitrile butadiene rubber (SBR).

14. In paragraph 1, The above finishing tape is an electrode assembly containing styrene butadiene rubber (SBR).

15. In paragraph 1, The above finishing tape includes a central portion and an outer portion, An electrode assembly in which the thickness of the finishing tape becomes thicker from the outer portion to the central portion.

16. In paragraph 1, An electrode assembly wherein the diameter of the jelly roll is 40 mm to 50 mm.

17. An electrode assembly including a jelly roll in which a first electrode, a separator, and a second electrode are sequentially laminated and wound; A case in which the electrode assembly is stored; and Including a finishing tape attached to wrap the outer surface of the jelly roll at least once, A secondary battery, wherein the above-mentioned finishing tape includes an overlapping portion formed by at least a portion of one end and the other end of the finishing tape overlapping in the winding direction of the jelly roll.

18. In paragraph 17, A secondary battery having a case diameter of 41 mm to 51 mm.

19. A step of sequentially stacking and winding a first electrode, a separator, and a second electrode to produce a jelly roll; and A method for manufacturing an electrode assembly, comprising a step of attaching the outer surface of the jelly roll to be wrapped at least once with a finishing tape.

20. In paragraph 19, The step of attaching the outer surface of the jelly roll by wrapping it with the above finishing tape at least once is as follows: A method for manufacturing an electrode assembly, comprising a step of attaching the finishing tape to wrap around the outer surface of the jelly roll, such that at least a portion of one end and the other end of the finishing tape overlap in the winding direction of the jelly roll to form an overlapping portion.

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