Secondary battery including vent plate and method for manufacturing secondary battery

Abstract

The present disclosure provides a secondary battery including a vent plate and a method for manufacturing the secondary battery. A secondary battery according to the present disclosure may comprise: an electrode assembly formed by winding a first electrode, a separator, and a second electrode; a case accommodating the electrode assembly; and a vent plate sealing an opening on one side of the case. The electrode assembly and the vent plate may be electrically insulated, and the center portion of the vent plate may protrude in a direction in which the electrode assembly accommodated in the case is located.

Description

Secondary battery including a vent plate and method for manufacturing a secondary battery

[0001] The present disclosure relates to a secondary battery comprising a vent plate and a method for manufacturing the secondary battery.

[0002] Unlike primary batteries, which cannot be recharged, secondary batteries are batteries capable of both charging and discharging. Low-capacity secondary batteries are used in small portable electronic devices such as smartphones, feature phones, laptop computers, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as power sources for motor drive systems and power storage batteries in hybrid and electric vehicles. Such secondary batteries include an electrode assembly consisting of a positive electrode and a negative electrode, a case housing the assembly, and electrode terminals connected to the electrode assembly.

[0003] Although rechargeable batteries are used in various environments due to their excellent electrical characteristics, conventional small batteries have had limitations in terms of designable energy density. Since the amount of electrical energy that can be stored is limited relative to the size and weight of the battery, there is a gradually increasing demand for large batteries with higher energy density in applications such as electric vehicles.

[0004] During the repeated charging and discharging of a secondary battery over a long period, gas is generated inside the battery, causing the internal pressure to rise. Additionally, heat is generated by electrochemical reactions within the battery, causing the cells to gradually deform or warp, resulting in changes to the overall specifications.

[0005] 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.

[0006] The problem that the present invention aims to solve is to provide a secondary battery and a method for manufacturing a secondary battery to solve the above technical problem.

[0007] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems can be clearly understood by those skilled in the art from the description of the invention below.

[0008] A secondary battery according to one embodiment of the present invention for solving the above technical problem comprises an electrode assembly formed by winding a first electrode, a separator, and a second electrode, a case housing the electrode assembly, and a vent plate sealing an opening on one side of the case, wherein the electrode assembly and the vent plate are electrically insulated, and the center of the vent plate may protrude in the direction in which the electrode assembly housed within the case is located.

[0009] According to one embodiment of the present disclosure, the vent plate may include a material exhibiting ferromagnetism.

[0010] According to one embodiment of the present disclosure, the vent plate may comprise ferrite or martensite-based stainless steel.

[0011] According to one embodiment of the present disclosure, the vent plate may include austenitic SUS.

[0012] According to one embodiment of the present disclosure, a step may exist between the center of the vent plate and the outer portion surrounding the center.

[0013] According to one embodiment of the present disclosure, the vent plate may have a convex arch shape in the direction in which the electrode assembly accommodated within the case is located.

[0014] According to one embodiment of the present disclosure, the vent plate may include a circumferential notch.

[0015] According to one embodiment of the present disclosure, the notch may be located on the outer portion surrounding the center of the vent plate.

[0016] According to one embodiment of the present disclosure, the case includes a clamping portion for fixing a vent plate, and the secondary battery may further include a current collector plate that electrically connects the electrode assembly and the case, and an insulating member interposed between the clamping portion and the vent plate.

[0017] According to one embodiment of the present disclosure, the diameter of the case may be 40 mm to 50 mm.

[0018] A method for manufacturing a secondary battery according to an embodiment of the present invention for solving a technical problem comprises the steps of winding a first electrode, a separator, and a second electrode to form an electrode assembly, inserting the electrode assembly into a case, and sealing an opening on one side of the case with a vent plate, wherein the electrode assembly of the secondary battery and the vent plate are electrically insulated, and the center of the vent plate may protrude in the direction in which the electrode assembly accommodated in the case is located.

[0019] A method for manufacturing a secondary battery according to one embodiment of the present disclosure may further include the step of removing internal air of a sealed case so that the center of the vent plate protrudes further in the direction in which the electrode assembly is located.

[0020] A method for manufacturing a secondary battery according to one embodiment of the present disclosure further includes the step of fixing a vent plate by bending a clamping portion of a case, and an insulating member may be interposed between the clamping portion and the vent plate.

[0021] According to some embodiments of the present disclosure, the structure of the vent plate of a secondary battery is modified to protrude in the direction of the electrode assembly inside the cell, thereby preventing deformation of the overall cell dimensions or specifications even with an increase in internal cell pressure.

[0022] According to some embodiments of the present disclosure, external protrusion of the central portion of the vent plate is prevented even during long-term use of the secondary battery, thereby extending the lifespan of the secondary battery and providing a standardized secondary battery cell.

[0023] According to some embodiments of the present disclosure, the material of the vent plate can be modified to improve durability and impart new properties to enable the movement and assembly of secondary battery cells using magnets.

[0024] However, 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.

[0025] 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 such drawings.

[0026] FIG. 1 is a cross-sectional view showing an example of a secondary battery according to one embodiment of the present disclosure.

[0027] FIG. 2 is a plan view showing the appearance of a vent plate before and after use according to one embodiment of the present disclosure.

[0028] FIG. 3 is a perspective view showing a vent plate according to one embodiment of the present disclosure.

[0029] FIG. 4 is a longitudinal cross-sectional view of a vent plate according to one embodiment of the present disclosure, cut along line AA of FIG. 3.

[0030] FIG. 5 is a cross-sectional view showing an example of a secondary battery according to one embodiment of the present disclosure.

[0031] FIG. 6 is a plan view showing a cross-section of a case before a vent plate is attached to it according to one embodiment of the present disclosure.

[0032] FIG. 7 is a cross-sectional view showing an example of a secondary battery according to one embodiment of the present disclosure.

[0033] FIG. 8 is a flowchart illustrating an example of a method for manufacturing a secondary battery according to the present disclosure.

[0034] 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 of the most 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0040] The statement that any component is positioned on the "upper (or lower) side" or the "upper (or lower) side" of a component implies not only that any component is positioned in contact with the upper (or lower) surface of said component, but also that another component may be interposed between said component and any component positioned on (or below) said component. Additionally, the area between the upper and lower parts of a component depicted in the drawings, or the remaining part excluding the upper and lower parts, may be referred to as a "side" or "lateral side." Furthermore, the direction facing the internal space of the component may be referred to as the "inner side," and the direction protruding into the open external space may be referred to as the "outer side." Such relative terms, such as "upper" and "upper side," may be used to describe the relationship between components depicted in the drawings, and the present disclosure is not limited by such terms.

[0041] Spatial relative terms such as "beneath," "below," "lower," "above," and "upper" may be used herein for ease of explanation to describe the relationship between one element or feature and another element(s) or feature(s) as illustrated in the drawings. 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, an element described as "below" or "below" is understood as "above" or "upper" of another element. Thus, the term "below" may encompass both the up and down directions.

[0042] 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.

[0043] 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 present disclosure relates to “one or more embodiments of the present disclosure.” Expressions such as “one or more” preceding a list of elements modify the entire list of elements and do not modify individual elements of the list.

[0044] 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.

[0045] 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.

[0046] The terms used in this specification are intended to describe embodiments of the present disclosure and are not intended to limit the present disclosure.

[0047] FIG. 1 is a cross-sectional view showing an example of a secondary battery according to one embodiment of the present disclosure.

[0048] Referring to FIG. 1, a secondary battery (100) according to one embodiment of the present invention may include an electrode assembly (110) formed by winding a first electrode, a separator, and a second electrode, a case (120) housing the electrode assembly (110), a vent plate (130) sealing an opening on one side of the case (120), and a current collector (140) located at the bottom of the vent plate (130).

[0049] 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 electrode to the first electrode. For example, if the first electrode is a positive electrode, the second electrode may be a negative electrode. Conversely, if the first electrode is a negative electrode, the second electrode may be a positive electrode.

[0050] In one embodiment, the electrode assembly (110) is formed in a jelly roll state by sequentially winding the first electrode, the separator, and the second electrode. The first electrode and the second electrode each include a coated portion in which an active material is applied to both sides of a substrate formed by a thin metal plate, and an uncoated portion (112) in which the substrate is exposed and the active material is not applied. As an example, the first electrode may form a positive electrode by coating a positive active material on an aluminum (Al) substrate, and the second electrode may form a negative electrode by coating a negative active material on a copper (Cu) substrate. The first electrode, the second electrode, and the separator may be impregnated with an electrolyte (not shown).

[0051] The outer surface of the electrode assembly (110) may include a separator or a substrate layer constituting the electrode. Specifically, the outer surface of the electrode assembly (110) may be one end of a separator that extends 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 of the electrode assembly (110) may be one end of a substrate layer formed by extending a blank portion of the substrate layer on which the active material constituting the first electrode or the second electrode is not coated.

[0052] For the purpose of explaining the invention, the secondary battery (100) in FIGS. 1 to 8 below is shown in the form of a cylindrical secondary battery, but the scope of the present disclosure is not limited thereto. The secondary battery (100) of the present invention is not limited to a cylindrical secondary battery and includes secondary batteries of any shape, such as a prismatic secondary battery, a pouch secondary battery, or a coin secondary battery.

[0053] The case (120) forms the overall exterior of the secondary battery (100) and may be formed of a conductive metal such as aluminum, aluminum alloy, stainless steel (e.g., SUS), or nickel-plated steel. Additionally, the case (120) may provide a space for accommodating the electrode assembly (110). For example, if the secondary battery (100) is a cylindrical secondary battery, the case (120) may have the shape of a cylinder.

[0054] The case (120) has a fully open opening to allow the electrode assembly (110) to be inserted on the other side. A vent plate (130) can be coupled to seal the opening after the electrode assembly (110) is inserted into the case (120). To seal the opening of the case (120), the case (120) may include a clamping part (122). The clamping part (122) will be described in detail later in FIG. 6.

[0055] The vent plate (130) is configured to cover the opening of the case (120) and seals the interior of the secondary battery (100) from the external environment to prevent leakage of electrolyte, etc., protects the internal components of the secondary battery (100) from external moisture or dust, and provides a welded or contact area to an external component (e.g., an external terminal) to electrically connect the secondary battery cell.

[0056] The electrode assembly (110) can be electrically connected to a current collector (140) located at the bottom of the vent plate (130). For example, the non-removable portion (112) of the electrode assembly (110) can be welded and joined to the current collector (140). The current collector (140) can protrude toward the electrode assembly (110) so as to be welded to the non-removable portion (112) of the electrode assembly (110).

[0057] Specifically, the unwelded portion (112) of the electrode assembly (110) and the current collector (140) may be welded using any one of ultrasonic welding, laser welding, resistance welding, TIG welding (Tungsten Inert Gas Welding), or a combination thereof. The welding method is not limited to the types of welding listed above, and various methods generally used for welding two materials may be used at the choice of a person skilled in the art.

[0058] Additionally, in one embodiment, the vent plate (130) may be electrically insulated from the current collector (140). As a result, the vent plate (130) may be electrically insulated from the electrode assembly (110). The secondary battery (100) may further include a gasket (not shown) interposed between the vent plate (130) and the current collector (140). Here, the gasket may perform an insulating function by being composed of a structure that creates a gap between the vent plate (130) and the current collector (140) while simultaneously sealing the secondary battery (100), or by a material that disconnects the electrical connection.

[0059] In one embodiment, the center (132) of the vent plate (130) may protrude in the direction in which the electrode assembly (110) housed within the case (120) is located. Specifically, the vent plate (130) may have a shape in which the outer portion (134) is positioned on the clamping portion (122) of the case (120), and the center (132) protrudes further toward the electrode assembly (110) than the clamping portion (122). The degree of protrusion of the center (132) may be varied according to selection within a range in which the center (132) does not come into contact with the current collector (140).

[0060] The shape and configuration of the vent plate (130) will be described later in FIGS. 3 to 5.

[0061] According to one embodiment of the present disclosure, the vent plate (130) may include a material exhibiting ferromagnetism. Specifically, the vent plate (130) may include at least a portion of a ferromagnetic material so that the secondary battery (100) can be moved and assembled by being fixed or attached to an external device or means that generates a magnetic field without mechanical assembly or chemical attachment processes.

[0062] For example, the vent plate (130) may comprise an alloy such as Alnico, Permalloy, Silicon Steel, Neodymium (NdFeB), composed of iron (Fe), nickel (Ni), cobalt (Co), manganese (Mn), zinc (Zn), chromium (Cr), titanium (Ti), or a combination including these.

[0063] According to one embodiment, the vent plate (130) may comprise a ferrite stainless steel (SUS) made of an alloy of iron and chromium. Specifically, at least a portion of the vent plate (130) may comprise SUS 430, SUS 409, SUS 446, or a combination including these.

[0064] According to one embodiment, the vent plate (130) may comprise a martensitic SUS made of an alloy of iron and chromium containing high carbon. Specifically, at least a portion of the vent plate (130) may comprise SUS 410, SUS 420, SUS 440, or a combination including these.

[0065] According to one embodiment of the present disclosure, the vent plate (130) may include a paramagnetistic SUS alloy. For example, the vent plate (130) may include an austenitic SUS alloy composed of iron, nickel, and chromium. Specifically, at least a portion of the vent plate (130) may include SUS 304, SUS 316, SUS 310, SUS 321, or a combination thereof. The austenitic SUS is an alloy containing 16 to 26% chromium, 6 to 12% nickel, and 62% to 78% iron, and may have excellent corrosion resistance and machinability compared to aluminum (Al), and excellent mechanical properties against external stress.

[0066] According to some embodiments of the present disclosure, by providing a vent plate (130) made of a paramagnetic SUS alloy material, the external protrusion of the center (132) of the vent plate (130) is prevented even during long-term use of the secondary battery (100), thereby extending the lifespan of the secondary battery (100) and providing a standardized secondary battery (100).

[0067] In addition, according to some embodiments of the present disclosure, the material of the vent plate (130) may be modified to a ferromagnetic material to improve durability, and new characteristics and processes may be imparted to enable the movement and assembly of the secondary battery (100) using an external device such as a magnet.

[0068] FIG. 2 is a plan view showing the appearance of a vent plate before and after use according to one embodiment of the present disclosure.

[0069] Referring to FIG. 2, the vent plate (230) according to one embodiment of the present disclosure may protrude outwardly from the electrode assembly (210) as the secondary battery is actually used. Specifically, according to the results of an actual use test for a secondary battery with a case (220) diameter of 40 mm to 50 mm, when the height difference between the center (242) of the vent plate (240) after swelling due to use of the secondary battery and the center (232) of the vent plate (230) before swelling is denoted as d, the d of the secondary battery that has reached the end of its lifespan is 0.25 mm to 0.5 mm. The description of the configuration other than that is the same as the description given above with reference to FIG. 1.

[0070] Compared to the illustrated embodiment of the present invention, the secondary battery of another embodiment corresponding to the control group includes the same electrode assembly (210) and case (220) as the secondary battery of the present invention, but the shape and material of the vent plate (230) may differ from the secondary battery of the present invention described above in FIG. 1. Specifically, the secondary battery vent plate of another embodiment may include an aluminum alloy.

[0071] In a secondary battery according to one embodiment of the present disclosure, the height difference (d) between the center (242) of the vent plate (240) after the lifespan of the secondary battery has ended and the center (232) of the vent plate (230) before use can be reduced to 25% compared to the height difference between the center of the vent plate of another embodiment including an aluminum alloy.

[0072] FIG. 3 is a perspective view showing a vent plate according to one embodiment of the present disclosure. FIG. 4 is a longitudinal cross-sectional view of a vent plate according to one embodiment of the present disclosure taken along line AA of FIG. 3.

[0073] Referring to FIGS. 3 and 4, a vent plate (300) according to one embodiment may include a center (310) and an outer portion (320) surrounding the center (310). Additionally, the heights of the center (310) and the outer portion (320) may differ, so that a step (330) exists between them. Specifically, the center (310) and the outer portion (320) of the vent plate (300) may be planes parallel to each other. Here, the center (310) may protrude in one direction (or downward direction) relative to the outer portion (320). Subsequently, when the vent plate (300) seals the opening of the case of the secondary battery, the vent plate (300) may be positioned such that the direction of protrusion of the center (310) is in the direction in which the electrode assembly is located.

[0074] According to one embodiment, the vent plate (300) may include a notch (340) configured to break when pressure exceeding a set value is applied. Specifically, the notch (340) may function as a vent that deforms or ruptures when the internal pressure of the secondary battery exceeds a certain pressure (operating pressure) to release gas generated inside the secondary battery to the outside of the secondary battery.

[0075] The location or shape of the notch (340) may vary. For example, the vent plate (300) may include a circumferential notch (340) as shown in FIGS. 3 and 4. The notch (340) may be formed continuously over the entire area along the circumferential direction of the vent plate (300), or it may be formed in multiple numbers spaced apart at predetermined intervals. The cross-section of the notch (340) may be semicircular or gradually narrowing wedge-shaped, but is not limited thereto.

[0076] As illustrated in FIG. 4, in one embodiment, a notch (340) may be formed on one side in the direction of the protrusion of the vent plate (300), that is, in the direction of the electrode assembly. In the event of an abnormal event such as a short circuit within the electrode assembly in the secondary battery, the notch (340) is directly exposed to the gas generated in the secondary battery and then receives concentrated internal pressure, allowing it to be easily cut to release the internal pressure of the secondary battery to the outside, thereby preventing a secondary explosion.

[0077] According to one embodiment of the present disclosure, the notch (340) may be located in the outer portion (320) to surround the center (310) of the vent plate (300). According to another embodiment of the present disclosure, the notch (340) may be located in the center (310) of the vent plate (300). Specifically, when the location of the notch (340) is in the center (310) of the vent plate (300), the fracture pressure of the notch (340) may be high, and when the location of the notch (340) is in the outer portion (320) of the vent plate (300), the fracture pressure of the notch (340) may be low. Accordingly, the location of the notch (340) on the vent plate (300) may be varied depending on the design of the fracture pressure of the notch (340).

[0078] FIG. 5 is a cross-sectional view showing an example of a secondary battery according to one embodiment of the present disclosure.

[0079] Referring to FIG. 5, a vent plate (530) according to one embodiment of the present disclosure may have a convex arch shape in the direction in which the electrode assembly (510) accommodated in the case (520) is located.

[0080] Specifically, the vent plate (530) may include a convex arch shape at its center (532). Additionally, the portion of the vent plate (530) that contacts the case (520), excluding the center (532), may include a ring-shaped plane to facilitate clamping. The heights of the ring-shaped plane and the center (532) of the vent plate (530) may differ from each other, so that a step may exist between them.

[0081] When the vent plate (530) seals the opening of the case (520) of the secondary battery, the vent plate (530) may be positioned such that the protruding direction of the center (532) is the direction in which the electrode assembly (510) is located. The degree of protrusion of the center (532) may be varied according to selection within a range in which the center (532) does not come into contact with the current collector (540).

[0082] According to some embodiments of the present disclosure, the structure of the vent plate (530) prevents the external protrusion of the center (532) of the vent plate (530) even during long-term use of the secondary battery, thereby extending the lifespan of the secondary battery and providing a standardized secondary battery cell.

[0083] Other details regarding the configuration are as described above with reference to Fig. 1.

[0084] FIG. 6 is a plan view showing a cross-section of a case before a vent plate is attached to it according to one embodiment of the present disclosure.

[0085] Referring to FIG. 6, the case (610) may have an opening on one side to allow an electrode assembly to be inserted. A vent plate (630) may be attached to seal the opening after the electrode assembly is inserted into the case (610). To seal the opening of the case (610), the case (610) may include a clamping part (612) for pressing and fixing the vent plate (630).

[0086] In one embodiment, the case (610) may include a clamping portion (612) for fixing a vent plate (630) positioned to seal an opening. Specifically, the clamping portion (612) is formed to be recessed towards the center in the diameter direction of the case (610) from one side around the opening of the case (610), thereby preventing vertical movement of the electrode assembly located on the lower side and simultaneously providing a structure in which the vent plate (630) seated on the upper side is fixed.

[0087] The outer portion (632) of the vent plate (630) has a larger diameter than the recessed structure of the clamping portion (612) and can be positioned over the recessed structure. The center (634) of the vent plate (630) has a smaller diameter than the recessed structure of the clamping portion (612) and can be positioned so that the center (634) protruding toward the electrode assembly is closer to the electrode assembly than the clamping portion (612). The notch (639) of the vent plate (630) can be located on the outer portion (632) near the center (634) of the vent plate (630) so as not to be obscured by the clamping portion (612) or the insulating member (650) to be described later for operation.

[0088] A secondary battery according to one embodiment may further include a current collector plate (620) that electrically connects the electrode assembly and the case (610). Additionally, the clamping portion (612) may provide a contact surface through which the current collector plate (620) and the case (610) can be electrically connected. Specifically, the current collector plate (620) may include a bottom portion (621) connected to the non-removable portion of the electrode assembly, a wing portion (622) connected to the clamping portion (612), and a hole (623) that penetrates the bottom portion (621) to absorb and mitigate vibration and shock and corresponds to the winding core of the electrode assembly. The wing portion (622) and the bottom portion (621) of the current collector plate (620) are integrally formed so that the electrode assembly and the case (610) can be electrically connected to each other.

[0089] A secondary battery according to one embodiment may further include an insulating member (650) interposed between a clamping part (612) and a vent plate (630). The insulating member (650) may be interposed between a current collector plate (620) and a vent plate (630) and between a current collector plate (620) and a case (610) to seal the periphery of the clamping part (612).

[0090] FIG. 7 is a cross-sectional view showing an example of a secondary battery according to one embodiment of the present disclosure.

[0091] Referring to FIG. 7, a secondary battery according to one embodiment of the present disclosure includes an electrode assembly (710) that performs charging and discharging, a case (720) that houses the electrode assembly (710), a first current collector plate (730) and a second current collector plate (750) connected to the electrode assembly (710), an electrode terminal (741), a vent plate (742), and a gasket (760). In FIG. 7, the vent plate (742) is shown positioned on the upper part of the secondary battery and the electrode terminal (741) is shown positioned on the lower part of the secondary battery, but is not limited thereto. Depending on the usage environment or requirements of the secondary battery, the vent plate (742) and the electrode terminal (741) may be changed to be positioned on the lower part and the upper part of the secondary battery, respectively.

[0092] The electrode assembly (710) is formed into a cylindrical jelly roll state with an empty core by winding the first electrode (711a, 711b), separator (713), and second electrode (712a, 712b). 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 by a thin metal plate, and an uncoated portion (711b, 712b) in which the substrate is exposed and the active material is not applied.

[0093] 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.

[0094] For example, the first electrode (711a, 711b) can be formed as a positive electrode by coating a positive active material on an aluminum (Al) substrate, and the second electrode (712a, 712b) can be formed as a negative electrode by coating a negative active material on a copper (Cu) substrate. The uncoated portion (711b) of the first electrode and the uncoated portion (712b) of the second electrode are respectively provided at both ends in the winding axis direction of the electrode assembly (710), but electrode terminals (741) and cases (720) having different polarities are provided together in the same direction. A vent plate (742) is located on the opposite side of the electrode terminal (741).

[0095] The case (720) is formed as a cylinder to house the electrode assembly (710), and the electrode terminal (741) and the vent plate (742) are respectively provided at both ends of the case (720) in the axial direction so as to face each other.

[0096] According to one embodiment of the present disclosure, the diameter of the case (720) may be 40 mm to 50 mm.

[0097] The electrode terminal (741) is connected to the first electrode (711a, 711b) via the first current collector plate (730) through a rivet (743), and the case (720) is connected to the second electrode (712a, 712b) via the second current collector plate (750). At this time, the vent plate (742) is electrically separated from the second current collector plate (750) and the case (720) and does not have polarity.

[0098] An electrode terminal (741) connected to the first electrode (711a, 711b) of the electrode assembly (710) inserted into the case (720) from the outside is installed on one side of the case. The case (720) has a through hole (721) that is partially open on one side.

[0099] For example, the electrode terminal (741) may be installed in a through hole (721) of the case (720) in a rivet structure. To this end, the electrode terminal (741) may be connected to a rivet (743). One end of the rivet (743) is welded to the first current collector plate (730) and positioned to pass through the through hole (721). The electrode terminal (741) is connected to the rivet (743) and positioned on the outside of the case (720). The electrode terminal (741) may be formed to protrude above the outer surface of the case (720) around the through hole (721) and used as an anode terminal. At this time, the first current collector plate (730) becomes an anode current collector plate.

[0100] At this time, the first current collector plate (730) is electrically connected to the unoccupied portion (711b) of the first electrode through a rivet (743) and is electrically and mechanically connected to the electrode terminal (741). The first current collector plate (730) is electrically connected to the electrode terminal (741) in a structure that reduces resistance by contacting most of the unoccupied 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 hermetic structure against the electrolyte by interposing an insulator (723) in the through hole (721).

[0101] Here, the insulator (723) may be made of a polymer comprising ethylene propylene rubber (EPDM), polypropylene (PP), polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), or a combination thereof.

[0102] 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 choice.

[0103] In one embodiment, the first current collector plate (730) may include a metal plate (731) comprising at least one bridge (732). For example, the first current collector plate (730) may be composed of a conductive metal, specifically a conductive metal such as nickel, aluminum, copper, silver, zinc, tin, stainless steel (e.g., SUS), or nickel-plated steel or a combination thereof (alloy). Additionally, the metal plate (731) and the bridge (732) constituting the first current collector plate (730) may all be made of the same material to form a single unit.

[0104] Here, the bridge (732) of the first collector plate (730) can be configured to break when a current exceeding a set value flows. For example, the bridge (732) normally operates as part of a circuit through which current flows, but when a current exceeding the necessary amount flows, it can act as a fuse that melts due to the heat generated to cut off the circuit.

[0105] An insulating tape (745) may be attached to one side of the first current collector plate (730). The insulating tape (745) may be interposed between the first current collector plate (730) and the case (720) or between the uninsulated portion (711b) of the first electrode and the case (720) to perform the function of electrically insulating each component. In one embodiment, the central portion of the insulating tape (745) may include a perforation (746) corresponding to the shape of a rivet (743) so that the rivet (743) can come into contact with the first current collector plate (730). Additionally, the insulating tape (745) may include a side wall (747) to wrap around a part of the electrode assembly (710).

[0106] Additionally, the case (720) has a fully open opening (722) to allow the electrode assembly (710) to be inserted on the other side. The vent plate (742) seals the opening (722) after the electrode assembly (710) is inserted into the case (720) and is electrically separated from the case (720).

[0107] At this time, the second current collector plate (750) is electrically connected to the non-electrical portion (712b) of the second electrode and is electrically connected to the case (720). The second current collector plate (750) is connected to the case (720) in a structure that reduces resistance by contacting most of the non-electrical portion (712b) of the second electrode.

[0108] The second current collector plate (750) includes a bottom portion (751) welded to the non-bonded portion (712b) of the second electrode and a wing portion (752) formed adjacent to the bottom portion (751) and welded to the beading portion (729). The second current collector plate (750) is formed by cutting and bending a circular plate, and is provided with a plurality of bottom portions (751) and wing portions (752), respectively, and is arranged alternately with one another along the circumferential direction. In one embodiment, the wing portion (752) can repeatedly form an axial (upward) bend and a radial (outer) bend of the electrode assembly (710).

[0109] In one embodiment, when the uncoated portion (712b) of the second electrode and the bottom portion (751) of the second current collector plate (750) are welded, the bottom portion (751) can form a weld line in the diameter direction of the second current collector plate (750). Thus, the bottom portion (751) can be evenly connected along the circumferential direction in the area of ​​the uncoated portion (712b) of the second electrode, and the wing portion (752) can be evenly connected along the circumferential direction in the area of ​​the beading portion (729). This enables a uniform current flow along the circumferential direction from the uncoated portion (712b) of the second electrode to the entire area of ​​the beading portion (729) of the case (720).

[0110] Additionally, the second collector plate (750) is provided with a hole (753) in the center, so it can absorb and mitigate deformation caused by welding between the bottom part (751) and the non-welded part (712b) of the second electrode, as well as vibrations and shocks that may be transmitted between the wing part (752) and the bottom part (751). The hole (753) may have a size within a range that can absorb vibrations and shocks without increasing current resistance between the wing part (752) and the bottom part (751).

[0111] The vent plate (742) is electrically separated from the second current collector plate (750) and installed in the opening (722) of the case (720) by a crimping process. Alternatively, the vent plate (742) is installed in the opening (722) of the case (720) through a welding process. The vent plate (742) may have the same or similar configuration as the vent plates (130, 230, 330, 530, 630) described with reference to FIGS. 1 to 6. Due to the connection of the second current collector plate (750), the case (720) can be used as a negative terminal. At this time, the second current collector plate (750) becomes a negative current collector plate.

[0112] The vent plate (742) may have a notch (744) formed on its inner surface. The notch (744) can be cut open to release internal pressure from the secondary battery to the outside in the event of an abnormal event in the secondary battery, thereby preventing a secondary explosion. Specifically, the notch (744) is designed to be easily cut open by receiving concentrated internal pressure during an abnormal event. The notch (744) may be formed over the entire area along the circumferential direction of the vent plate (742), or it may be formed in multiple locations spaced apart at set intervals.

[0113] The gasket (760) is interposed between the second current collector plate (750) and the vent plate (742) and between the second current collector plate (730) and the case (720), and acts as a seal through the beading portion (729) or the clamping process. Additionally, the gasket (760) can form an airtight structure against the electrolyte between the second current collector plate (730) and the opening (722) of the case (720).

[0114] For example, the gasket (760) may include polymer materials 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), or ceramics, but is not limited thereto, and may be any one of the suitable compounds used as insulating materials in the industry.

[0115] The sealing tape (790) can be attached to wrap the outer surface of the jelly roll of the electrode assembly (710) at least once. Additionally, the electrode assembly (710) is inserted into the case (720) with the sealing tape (790) attached, and the sealing tape (790) can be positioned between the electrode assembly (710) and the case (720). Thus, the secondary battery assembled is prevented from moving the electrode assembly (710) up and down or forward and backward within the case (720), thereby preventing the separation of terminals or damage to the components, and even when the electrode assembly (710) expands due to charging and discharging, cracks in the case (720) or the electrode assembly (710) caused by excessive expansion of the electrode assembly (710) can be suppressed.

[0116] A secondary battery according to one embodiment of the present invention may be applied to automobiles, mobile phones, and / or various types of electric devices, etc., but the present invention is not limited thereto.

[0117] FIG. 8 is a flowchart illustrating an example of a method for manufacturing a secondary battery according to the present disclosure.

[0118] A method for manufacturing a secondary battery (800) according to one embodiment of the present invention may be disclosed by winding a first electrode, a separator, and a second electrode to form an electrode assembly (S810). Here, the diameter of the electrode assembly may be 40 mm to 50 mm.

[0119] Afterwards, the electrode assembly can be inserted into the case (S820).

[0120] Then, one side opening of the case can be sealed with a vent plate (S830). Here, the electrode assembly of the secondary battery and the vent plate are electrically insulated, and the center of the vent plate may protrude in the direction in which the electrode assembly housed within the case is located. Specifically, in one embodiment, a step may exist between the center of the vent plate and the outer portion surrounding the center. In another embodiment, the vent plate may have a convex arch shape in the direction in which the electrode assembly housed within the case is located.

[0121] According to one embodiment, the vent plate may include a material exhibiting ferromagnetism. For example, the vent plate may include ferrite or martensitic stainless steel. According to another embodiment, the vent plate may include austenitic stainless steel.

[0122] Additionally, a vent plate according to one embodiment may include a circumferential notch. Here, the notch may be located on the outer edge surrounding the center of the vent plate.

[0123] A method for manufacturing a secondary battery (800) according to one embodiment of the present disclosure may further include a step of removing internal air of a sealed case using an air pressure regulating device, such as a vacuum pump, so that the center of the vent plate protrudes further in the direction where the electrode assembly is located. Additionally, through the step of removing internal air of the sealed case, the interior of the secondary battery may have negative pressure relative to the exterior. Due to the negative pressure inside the secondary battery, the internal gas capacity of the secondary battery according to the present invention increases, and accordingly, the lifespan of the secondary battery may increase. Specifically, the magnitude of the negative pressure inside the secondary battery may be set to 0.5 kgf / cm2 to 0.7 kgf / cm2.

[0124] A method (800) for manufacturing a secondary battery according to one embodiment of the present disclosure may further include the step of fixing a vent plate by bending a clamping portion of a case. Here, an insulating member may be interposed between the clamping portion and the vent plate.

[0125] According to some embodiments of the present disclosure, the structure of the vent plate of a secondary battery is modified to protrude in the direction of the electrode assembly inside the cell, thereby preventing deformation of the overall cell dimensions or specifications even with an increase in internal cell pressure.

[0126] The flowchart of FIG. 8 and the description above are merely examples of the present disclosure, and the scope of the present disclosure is not limited to the flowchart of FIG. 8 and the description above. For example, one or more steps in the flowchart and the description above may be added, changed, or deleted, the order of one or more steps may be changed, and one or more steps may be performed simultaneously.

[0127] Although the present invention has been described above by means of 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. Since various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention without departing from it, by those skilled in the art to which the present invention belongs, the present invention is not limited by the aforementioned embodiments and attached drawings.

Claims

1. An electrode assembly formed by winding a first electrode, a separator, and a second electrode; A case housing the above electrode assembly; and A vent plate that seals an opening on one side of the above case Includes, The electrode assembly and the vent plate are electrically insulated, A secondary battery, wherein the center of the above-mentioned vent plate protrudes in the direction in which the electrode assembly accommodated within the above-mentioned case is located.

2. In Paragraph 1, The above vent plate is a secondary battery comprising a ferromagnetic material.

3. In Paragraph 2, The above vent plate comprises a ferrite or martensitic SUS, a secondary battery.

4. In Paragraph 1, The above vent plate comprises austenitic SUS, a secondary battery.

5. In Paragraph 1, A secondary battery having a step difference between the central part of the above-mentioned vent plate and the outer part surrounding the central part.

6. In Paragraph 1, The above-mentioned vent plate has a convex arch shape in the direction in which the electrode assembly accommodated within the case is located, in a secondary battery.

7. In Paragraph 1, The above vent plate is a secondary battery including a circumferential notch.

8. In Paragraph 7, The above notch is located on the outer edge surrounding the center of the above vent plate, a secondary battery.

9. In Paragraph 1, The above case includes a clamping part for fixing the vent plate, and The above secondary battery is, A current collector plate that electrically connects the electrode assembly and the case; and A secondary battery further comprising an insulating member interposed between the clamping portion and the vent plate.

10. In Paragraph 1, A secondary battery having a case diameter of 40 mm to 50 mm.

11. A step of forming an electrode assembly by winding the first electrode, the separator, and the second electrode; The step of inserting the above electrode assembly into a case; and The method includes the step of sealing one side opening of the above case with a vent plate, and The electrode assembly and the vent plate are electrically insulated, A method for manufacturing a secondary battery, wherein the center of the above-mentioned vent plate protrudes in the direction in which the electrode assembly accommodated in the above-mentioned case is located.

12. In Paragraph 11, A method for manufacturing a secondary battery, further comprising the step of removing internal air of the sealed case so that the center of the vent plate protrudes further in the direction in which the electrode assembly is located.

13. In Paragraph 11, The method further includes the step of fixing the vent plate by bending the clamping portion of the above case, and A method for manufacturing a secondary battery, wherein an insulating member is interposed between the clamping part and the vent plate.

14. In Paragraph 11, A method for manufacturing a secondary battery, wherein the above-mentioned vent plate comprises a material exhibiting ferromagnetism.

15. In Paragraph 11, A method for manufacturing a secondary battery, wherein the above-mentioned vent plate comprises ferrite or martensite-based SUS (stainless steel).

16. In Paragraph 11, A method for manufacturing a secondary battery, wherein the above-mentioned vent plate comprises an austenitic SUS.

17. In Paragraph 11, A method for manufacturing a secondary battery, wherein a step exists between the central part of the above-mentioned vent plate and the outer part surrounding the central part.

18. In Paragraph 11, A method for manufacturing a secondary battery, wherein the above-mentioned vent plate has a convex arch shape in the direction in which the electrode assembly accommodated within the above-mentioned case is located.

19. In Paragraph 11, A method for manufacturing a secondary battery, wherein the above-mentioned vent plate includes a cylindrical notch.

20. In Paragraph 19, A method for manufacturing a secondary battery, wherein the above notch is located on the outer portion surrounding the center of the above vent plate.

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