Secondary battery

Abstract

A secondary battery having a structure in which an exhaust port is provided in a sealing portion such that a portion of the sealing portion provided with the exhaust port has a low bonding force (which is generated by fusion) so that the exhaust port is not easily released if a secondary battery made of steel or stainless steel (SUS) having a plating layer formed on a surface thereof is expanded by internal pressure. And the exhaust port is easy to break, so that the safety is improved. A secondary battery includes an electrode assembly having a positive electrode plate, a negative electrode plate, and a separator between the positive electrode plate and the negative electrode plate, and a case configured to receive the electrode assembly. The housing includes a metal layer and a sealing portion sealed on at least three sides by fusion. The sealing portion includes at least one exhaust port.

Description

Technical Field

[0001] The embodiment relates to a secondary battery. Background Art

[0002] A secondary battery is an electric power storage system that converts electrical energy into chemical energy, stores the chemical energy, and provides high energy density. Compared with non-rechargeable primary batteries, secondary batteries are rechargeable and are widely used in IT devices such as smart phones, mobile phones, laptop computers, and tablet computers. Recently, interest in electric vehicles that prevent environmental pollution has increased, and high-capacity secondary batteries are adopted in electric vehicles. Secondary batteries require characteristics such as high density, high output, and stability.

[0003] The information disclosed in this section is only for enhancing the understanding of the background of the present disclosure, and thus it may include information that does not form the prior art. Summary of the Invention

[0004] The embodiment provides a secondary battery configured to have a structure in which an exhaust port is provided in a sealing portion such that a portion of the sealing portion provided with the exhaust port has a low bonding force (the bonding force is generated by fusion) between a case lid and a case base, so that if the secondary battery made of steel or stainless steel (SUS) having a plating formed on its surface expands due to internal pressure, the exhaust port is easily broken, thereby improving safety.

[0005] It should be noted that the object of the present disclosure is not limited to the object described above, and other objects not mentioned in the present disclosure will be clearly understood by those skilled in the art from the following description.

[0006] The secondary battery according to the embodiment includes an electrode assembly and a case. The electrode assembly has a positive electrode plate, a negative electrode plate, and a separator provided between the positive electrode plate and the negative electrode plate. The case is configured to accommodate the electrode assembly. The case includes a metal layer. The case includes a sealing portion sealed by fusion on at least three sides of the case, and the sealing portion is provided with at least one exhaust port.

[0007] The metal layer may be made of steel or stainless steel (SUS) having a plating formed on its surface.

[0008] The exhaust port may be located at a substantially center of the sealing portion provided at one side of the case.

[0009] The secondary battery may include a positive electrode lead tab that contacts and is electrically connected to the positive electrode plate of the electrode assembly. A part of the positive electrode lead tab is exposed outside the housing. The secondary battery further includes a negative electrode lead tab that contacts and is electrically connected to the negative electrode plate of the electrode assembly. A part of the negative electrode lead tab is exposed outside the housing. The positive electrode lead tab and the negative electrode lead tab may be exposed to the outside from one side of the housing, and a sealing portion is located on the said one side of the housing.

[0010] The vent may be between the positive electrode lead tab and the negative electrode lead tab.

[0011] The sealing portion may include a first sealing portion extending in a second direction, which is the width direction of the housing. The first sealing portion may be located on one side of the housing, and the positive electrode lead tab and the negative electrode lead tab are exposed from the said one side of the housing. The sealing portion may further include two second sealing portions extending from one end of the first sealing portion and the other end of the first sealing portion opposite to the said one end. The two second sealing portions extend in a first direction, which is the longitudinal direction of the housing.

[0012] The vent may be substantially at the center of the first sealing portion or substantially at the center of any one of the second sealing portions.

[0013] The vent may be substantially at the center of the second sealing portion in the first direction.

[0014] The vent may be substantially located at the center of the first sealing portion in the second direction.

[0015] The vent may be spaced apart from the center of the second sealing portion in the first direction.

[0016] The vent may be a notch in the edge of the sealing portion.

[0017] The notch of the vent may be covered with an adhesive or a UV curable material.

[0018] The notch of the vent may be substantially perpendicular to the edge or at a predetermined angle to the edge.

[0019] The width of the sealing portion in the part provided with the vent may be at least about 50% of the width of the sealing portion in the remaining part of the sealing portion.

[0020] The pattern of the heat fusion layer of the sealing portion may have a smaller width at the part where the vent is located than at the remaining part of the sealing portion.

[0021] The housing may include a housing body and a housing cover. The housing body includes a recess configured to receive an electrode assembly and an extension portion extending outward from the recess. The housing cover is joined to the extension portion of the housing body by fusion, and the sealing portion may be the portion where the extension portion and the housing cover are joined to each other by fusion.

[0022] Each of the housing body and the housing cover may have a multi-layer structure including a stack body having an inner layer made of an insulating heat-fusion layer, a metal layer made of steel or stainless steel (SUS) having a plating formed on its surface, and an outer layer made of an insulating material.

[0023] The exhaust port may include two or more exhaust ports. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings incorporated in this specification illustrate preferred embodiments and, together with the detailed description of the subsequent exemplary embodiments, further illustrate the technical idea of the present disclosure, and the present disclosure should not be construed as being limited to the content shown in these drawings. In the drawings:

[0025] Figure 1 is a perspective view showing a secondary battery according to an embodiment;

[0026] Figure 2 is Figure 1 an exploded perspective view of the secondary battery shown in ;

[0027] Figure 3 is a schematic view showing Figure 1 and Figure 2 the structure of the housing in the secondary battery of ;

[0028] Figure 4 is a schematic view showing Figure 1 and Figure 2 the exploded perspective view of the electrode assembly in the secondary battery of ;

[0029] Figure 5 is Figure 4 the assembled perspective view of the electrode assembly shown in ;

[0030] Figure 6 is a perspective view showing Figure 1 and Figure 2 another embodiment of the electrode assembly in the secondary battery of ;

[0031] Figure 7 is a top view showing the position of the exhaust port in the secondary battery of Figure 1 and Figure 2 according to an embodiment of the present disclosure; and

[0032] Figures 8 to 11 is a view showing according to other embodiments of the present disclosureFigure 1 and Figure 2 Top view of the position of the exhaust port in a secondary battery Detailed implementation mode

[0033] Hereinafter, the implementation mode will be described in detail with reference to the accompanying drawings. It should be understood that the terms or words used in the specification and the appended claims should not be construed as limited to the general meaning and dictionary meaning, but should be interpreted based on the principle that allows the inventor to define appropriate terms for the best explanation, based on the meaning and concept according to the technical idea of the present disclosure. The implementation modes described in this specification and the structures shown in the drawings are only the most preferred implementation modes, not for all the technical ideas of the present disclosure. Therefore, it should be understood that various alternative equivalents and modifications may be possible when submitting this application. As used herein, the terms "comprising" (or "including") and / or "comprising... of" (or "including... of") are intended to indicate the existence of the stated drawings, numbers, steps, operations, components, elements, and / or their groups, and do not exclude the existence or addition of one or more other drawings, numbers, steps, operations, components, elements, and / or groups.

[0034] The drawings may not be to scale, and some components may be exaggerated in size to facilitate understanding of the present disclosure. In different implementation modes, the same components may be represented by the same reference numerals.

[0035] Referring to two comparable things as "the same" means that they are "substantially the same". Therefore, substantially the same may include deviations considered to be low in the art (such as deviations less than 5%). If a parameter is uniform in a given region, this may mean that the parameter is uniform from an average perspective.

[0036] Although various components are described using first, second, etc., the components are not limited by these terms. These terms are only used to distinguish one component from another component, and unless otherwise specified, the first component may be the second component.

[0037] Throughout the specification, unless otherwise specified, each component may be singular or plural.

[0038] If any configuration is set "above" (or "below") or "on" a component (or "beneath"), this may not only mean that the configuration is set adjacent to the upper surface (or lower surface) of the component, but also mean that another configuration may be interposed between the component and the configuration set on (or below) the component.

[0039] It should also be understood that if a component is described as "connected", "coupled" or "linked" to another component, the components can be directly connected or linked to each other, another component can be "interposed" between the other components, or the components can be "connected", "coupled" or "linked" to each other via another component.

[0040] Throughout the specification, unless otherwise specified, reference to "A and / or B" means A, B, or A and B, and reference to "C to D" means C or higher and D or lower, unless otherwise specified.

[0041] Figure 1 is a perspective view showing a secondary battery according to an embodiment, Figure 2 is Figure 1 an exploded perspective view of the secondary battery shown in Figure 3 and is a schematic view showing Figure 1 and Figure 2 the structure of the case in the secondary battery of.

[0042] Referring to Figures 1 to 3 , the secondary battery 100 may include an electrode assembly 110 and a case 120.

[0043] The electrode assembly 110 may be received in the case 120 having an electrolyte. In one or more embodiments, the electrolyte may include a lithium salt (such as LiPF6 or LiBF4) in an organic solvent (such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC)).

[0044] The electrode assembly 110 may include a negative electrode plate as a first electrode plate, a positive electrode plate as a second electrode plate, and a separator between the positive electrode plate and the negative electrode plate. The positive electrode plate may include a positive electrode lead tab 130 electrically connected to an uncoated portion of the positive electrode, and the negative electrode plate may include a negative electrode lead tab 140 electrically connected to an uncoated portion of the negative electrode. A first insulating tape 141 for insulating from the case 120 may be attached to the negative electrode lead tab 140, and a second insulating tape 131 for insulating from the case 120 may be attached to the positive electrode lead tab 130.

[0045] An exploded perspective view and an assembled perspective view of the electrode assembly 110 applicable to the secondary battery 100 are shown in Figure 4 and Figure 5 respectively. As shown in Figure 4 and Figure 5As shown in the figure, the electrode assembly 110 may include a negative electrode plate 112, a positive electrode plate 111, and a separator 113 disposed between the negative electrode plate 112 and the positive electrode plate 111. The electrode assembly 110 may be a stacked electrode assembly, in which a stack of the negative electrode plate 112, the separator 113, and the positive electrode plate 111 is repeatedly stacked multiple times. In other embodiments, as Figure 6 shown in the figure, the electrode assembly 110 may be a wound electrode assembly, in which a stack of the negative electrode plate 112, the separator 113, and the positive electrode plate 111 is wound. Figure 6 The electrode assembly 110 depicted in the figure may be referred to as an electrode core.

[0046] Figure 4 and Figure 5 The stacked electrode assembly 110 shown in the figure will be described. The electrode assembly 110 may be formed by sequentially stacking the positive electrode plate 111, the separator 113, and the negative electrode plate 112 (each of which is formed in the shape of a thin plate or film) into a cubic shape. The electrode assembly 110 may be formed into a cubic shape by sequentially stacking the separator 113, the positive electrode plate 111, the separator 113, and the negative electrode plate 112 multiple times in the third direction z.

[0047] The positive electrode plate 111 may be formed by applying a positive electrode active material (such as graphite or carbon) to a positive electrode current collector made of a metal foil (such as aluminum). The positive electrode active material may be formed on one surface or the opposite surface of the positive electrode current collector; however, the present disclosure is not limited thereto. In one or more embodiments, a chalcogenide compound may be used as the positive electrode active material. In one or more embodiments, a composite metal oxide (such as LiCoO2, LiMn2O4, LiNiO2, or LiNiMnO2) may be used as the positive electrode active material. A positive electrode uncoated portion (to which the positive electrode active material is not applied) may be formed at a part of the positive electrode current collector. The positive electrode current collector may include a positive electrode uncoated portion 111c (which is a portion where the positive electrode active material is not applied). The positive electrode uncoated portion 111c may be a positive electrode tab 111c, which is a channel for current to flow between the positive electrode plate 111 and the outside of the positive electrode. The positive electrode tab 111c may protrude from one end of the positive electrode plate 111 in the first direction x. The positive electrode tab 111c may be on one side of the positive electrode plate 111 in the second direction y and at one end of the positive electrode plate 111 in the first direction x. In the electrode assembly 110, the positive electrode tabs 111c of the plurality of stacked positive electrode plates 111 may be aligned or substantially aligned at the same position in the third direction z.

[0048] A plurality of positive electrode tabs 111c can be electrically connected to a single positive electrode lead tab 130 and can extend and protrude from the interior of the housing 120 in an outward direction. The positive electrode lead tab 130 can be formed in the shape of a flat plate having a thickness greater than the thickness of each positive electrode tab 111c. The second insulating tape 131 can be between the positive electrode lead tab 130 and the housing 120. The second insulating tape 131 can ensure electrical isolation between the housing 120 and the positive electrode lead tab 130.

[0049] The positive electrode active material 111b can be applied to a positive electrode current collector (which is a plate-shaped metal foil), and a separate positive electrode plate 111 having a single positive electrode tab 111c can be formed by stamping. Considering the phenomenon of lithium ion precipitation that may intermittently occur on the negative electrode plate 112 during charging, the positive electrode plate 111 can have dimensions smaller than those of the negative electrode plate 112 in the first direction x and the second direction y (i.e., the length direction and the width direction). The negative electrode plate 112 can have a larger planar size than the positive electrode plate 111.

[0050] The negative electrode plate 112 can be formed by applying a negative electrode active material 112b (such as a transition metal oxide) to a negative electrode current collector made of a metal foil (such as copper or nickel), and can include a negative electrode uncoated portion 112c (which is a portion where the negative electrode active material is not applied). In one or more embodiments, a carbon-based material, Si, Sn, tin oxide, tin alloy composite, transition metal oxide, lithium metal nitride, or metal oxide can be used as the negative electrode active material. The negative electrode uncoated portion 112c can be a negative electrode tab 112c, which is a channel for current to flow between the negative electrode plate 112 and the outside of the negative electrode. The negative electrode tab 112c can protrude from one end of the negative electrode plate 112 in the first direction x. The negative electrode tab 112c can be located at one end of the negative electrode plate 112 in the first direction x and on one side of the negative electrode plate 112 in the second direction y. The negative electrode tab 112c can be on one side of the negative electrode plate 112, and this side of the negative electrode plate 112 is opposite to the side from which the positive electrode tab 111c of the positive electrode plate 111 extends. The negative electrode tab 112c can protrude in the same direction as the positive electrode tab 111c and can be parallel (or substantially parallel) to the positive electrode tab 111c. In the electrode assembly 110, the negative electrode tabs 112c of a plurality of stacked negative electrode plates 112 can be aligned (or substantially aligned) at the same position in the third direction z.

[0051] The negative electrode active material can be applied to a negative electrode current collector (which is a plate-shaped metal foil), and a separate negative electrode plate 112 having a single negative electrode tab 112c can be formed by stamping.

[0052] A plurality of negative electrode tabs 112c can be electrically connected to a single negative electrode lead tab 140, and can extend and protrude from the inside of the housing 120 in an outward direction. The negative electrode lead tab 140 can be formed in the shape of a flat plate having a thickness greater than the thickness of each negative electrode tab 112c. A first insulating tape 141 can be between the negative electrode lead tab 140 and the housing 120. The first insulating tape 141 can ensure electrical isolation between the housing 120 and the negative electrode lead tab 140.

[0053] The separator 113 can be located between the positive electrode plate 111 and the negative electrode plate 112 to prevent electrical short - circuit and enable the movement of transition metal ions, and can be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. However, the present disclosure is not limited to these materials of the separator 113.

[0054] To more reliably prevent short - circuit between the positive electrode plate 111 and the negative electrode plate 112, the separator 113 can be formed to have a width and a length greater than those of the positive electrode plate 111 and the negative electrode plate 112 in both the first direction x and the second direction y. That is, the separator 113 can have a planar size larger than each of the positive electrode plate 111 and the negative electrode plate 112.

[0055] The separator 113 can be formed such that the thickness of one end of the separator 113 in the first direction x is greater than the thickness of the remaining portion of the separator 113. In one or more embodiments, the entire one end of the separator 113 in the first direction x can have an insulating portion having a thickness greater than that of the remaining portion of the separator 113. The insulating portion can overlap a part of each of the positive electrode tab 111c and the negative electrode tab 112c in the third direction z. The insulating portion can overlap a portion of the positive electrode tab 111c adjacent to the positive electrode current collector in the third direction z, and can overlap a portion of the negative electrode tab 112c adjacent to the negative electrode current collector in the third direction z.

[0056] Figure 6 is an exploded perspective view showing another embodiment of an electrode assembly of a secondary battery. Figure 6 The electrode assembly 110 shown in can be formed by stacking the positive electrode plate 111, the separator 113, and the negative electrode plate 112 and winding the stack into a pole core.

[0057] The positive electrode plate 111 can be formed by applying a positive electrode active material 111b (such as graphite or carbon) to a positive electrode current collector 111a made of a metal foil (such as aluminum), and may include a positive electrode uncoated portion 111c or a positive electrode tab 111c (which is a portion where the positive electrode active material 111b is not applied). The positive electrode tab 111c may include a plurality of positive electrode tabs 111c, and the positive electrode tab 111c may be located at one end of the electrode assembly 110 in the first direction x and on one side of the electrode assembly 110 in the second direction y. In the electrode assembly 110, the positive electrode tabs 111c of the wound positive electrode plate 111 may be aligned (or substantially aligned) at the same position in the third direction z.

[0058] The negative electrode plate 112 can be formed by applying a negative electrode active material 112b (such as a transition metal oxide) to a negative electrode current collector 112a made of a metal foil (such as copper or nickel), and may include a negative electrode uncoated portion 112c or a negative electrode tab 112c (which is a portion where the negative electrode active material 112b is not applied). The negative electrode tab 112c may include a plurality of negative electrode tabs 112c, and the negative electrode tab 112c may be located at one end of the electrode assembly 110 in the first direction x and on one side of the electrode assembly 110 in the second direction y. The negative electrode tab 112c may be on one side of the negative electrode plate 112, and this side of the negative electrode plate 112 is opposite to the side from which the positive electrode tab 111c of the positive electrode plate 111 extends. In the electrode assembly 110, the negative electrode tabs 112c of the wound negative electrode plate 112 may be aligned (or substantially aligned) at the same position in the third direction z.

[0059] The separator 113 may be between the positive electrode plate 111 and the negative electrode plate 112 to prevent electrical short - circuit and enable the movement of transition metal ions. The separator 113 may be similar to the separator 113 described in reference Figure 4 and Figure 5 description.

[0060] The housing 120 may be made of a rectangular film extending in the first direction x (which is the longitudinal direction of the housing 120), and may include a housing body 121 and a housing cover 122 that are hingedly coupled to each other.

[0061] The electrode assembly 110 may be accommodated in a recess 123 in the housing body 121 of the housing 120, and the housing cover 122 may be folded and coupled to the housing body 121 so that the housing 120 is sealed. The housing 120 may be referred to herein as a pouch for a secondary battery.

[0062] The housing 120 can be formed by folding a rectangular film extending in the first direction x around or relative to a folding portion 124 extending in the second direction y, where the second direction y is a direction perpendicular (or substantially perpendicular) to the first direction x and is the width direction of the housing 120. In one or more embodiments, the housing body 121 and the housing cover 122 can be separate components, and the folding portion 124 may not be provided. In the present disclosure, the housing 120 is not limited to an integrated housing (where the housing body 121 and the housing cover 122 are formed on or by a single film). However, hereinafter, for convenience of description, an example where the housing body 121 and the housing cover 122 are formed on a single rectangular film will be described.

[0063] The housing cover 122 can have a rectangular flat shape. The housing cover 122 can contact the housing body 121 and can be coupled to the housing body 121 via the folding portion 124. The housing cover 122 can cover the upper portion of the housing body 121.

[0064] The housing body 121 can include a recess 123 and an extension portion 125 surrounding one or more portions of the recess 123. The housing body 121 can include a recess 123 at approximately the center (where the electrode assembly 110 is received) and an extension portion 125 extending substantially in an outward direction from three sides of the recess 123. For convenience, the edge of the housing body 121 is defined as the extension portion 125, and this edge of the housing body 121 is positioned outward in the plane surrounding the recess 123, and the recess 123 is sealed with the edge of the housing cover 122. The extension portion 125 can be parallel (or substantially parallel) to the housing cover 122 and be coupled to the plane of the housing cover 122. The recess 123 of the housing body 121 can be formed by pressing or stretching so as to have a sufficient size to receive the electrode assembly 110. In one or more embodiments, the extension portion 125 can extend from the four sides of the recess 123 in an outward direction.

[0065] In one or more embodiments where the housing body 121 and the housing cover 122 are separate components, the extension portion 125 can be provided at the portion where the folding portion 124 is located. If the housing body 121 and the housing cover 122 are integrated into a single component, the extension portion 125 can be provided at the housing body 121 adjacent to the folding portion 124. However, in one or more embodiments, the extension portion 125 may not be provided at the housing body 121 adjacent to the folding portion 124.

[0066] Each of the housing cover 122 and the housing body 121 may include an inner layer 120a, a metal layer 120b, and an outer layer 120c. The inner layer 120a and the outer layer 120c may be formed on one surface and the other surface (i.e., the opposite surface) of the metal layer 120b, respectively. The metal layer 120b may be between the inner layer 120a and the outer layer 120c. The housing cover 122 and the housing body 121 may have the inner layer 120a on their surfaces facing each other, and the outer layer 120c on their surfaces facing the outside (e.g., away from each other). The housing cover 122 and the housing body 121 may have the same layer structure. The metal layer 120b may be a layer configured to maintain the mechanical strength of the housing 120 and block the introduction of gas into the housing and the discharge of gas from the housing. The metal layer 120b may include steel or stainless steel (SUS) with a plating formed on its surface. Since the housing 120 includes the metal layer 120b made of steel or stainless steel with a plating formed on its surface, the housing 120 may have a lower expansion rate compared to conventional aluminum in the case where gas is generated in the battery and the pressure in the battery increases.

[0067] Since the metal layer 120b is made of steel or stainless steel with a plating formed on its surface, the rigidity of the housing 120 may be increased compared to a case where other aspects are comparable to those using conventional aluminum.

[0068] The inner layer 120a may be a layer configured to protect the metal layer 120b from the influence of the electrolyte. The inner layer 120a may include an insulating heat-fused layer. In some embodiments, the inner layer 120a may include a polypropylene-based resin to stabilize the heat fusibility, heat resistance, and chemical resistance of the battery; however, the present disclosure is not limited thereto. The outer layer 120c may be a layer configured to protect the metal layer 120b from the influence of the external environment. Considering heat resistance, pinhole resistance, abrasion resistance, etc., the outer layer 120c may include an insulating material. In some embodiments, the outer layer 120c may include polyethylene terephthalate (PET) resin and / or nylon resin; however, the present disclosure is not limited thereto.

[0069] The housing cover 122 may cover the portion of the housing body 121 where the recess 123 is formed, and the edge of the recess 123 and the edge of the housing cover 122 may be heat-fused to each other. The inner layer 120a of the housing body 121 and the inner layer 120a of the housing cover 122 may be in contact with each other and bonded to each other by heat fusion along the extension portion 125.

[0070] In an embodiment where the extension portion 125 and the case cover 122 are in contact with each other and heat-fused to each other, the insulating tapes 131 and 141 of the positive electrode lead tab 130 and the negative electrode lead tab 140 may be between the extension portion 125 and the case cover 122. The portion of the case 120 sealed by the fusion between the extension portion 125 and the case cover 122 may be referred to as a sealing portion 126. The case 120 may be provided with the sealing portion 126 on at least three sides thereof.

[0071] The case 120 may have at least one exhaust port 129 in the sealing portion 126. The portion of the sealing portion 126 provided with the exhaust port 129 may be a portion of the sealing portion 126 that undergoes a lower bonding force (which is generated due to fusion) than the remaining portion of the sealing portion 126. The sealing portion 126 may include a first sealing portion 126a on the side from which the positive electrode lead tab 130 and the negative electrode lead tab 140 protrude. The first sealing portion 126a extends in the second direction y. The sealing portion 126 may further include two second sealing portions 126b configured to connect opposite ends of the folded portion 124 and opposite ends of the first sealing portion 126a to each other. The second sealing portions 126b extend in the first direction x. The first sealing portion 126a may connect corresponding ends of the two second sealing portions 126b to each other. The length of the second sealing portion 126b in the first direction x may be greater than the length of the first sealing portion 126a in the second direction y (for example, the second sealing portion 126b may be longer than the first sealing portion 126a). The case 120 may be most affected by an increase in the internal pressure of the case 120 at approximately the center of the second sealing portion 126b (which has a greater length than the first sealing portion 126a).

[0072] In one or more embodiments, as Figure 7 shown, in the secondary battery 100, the exhaust port 129 may be located at approximately the center in the first direction x of one of the second sealing portions 126b. In the case 120, the exhaust port 129 may be located at the center (or substantially or approximately the center) of the second sealing portion 126b in the first direction x, which is most affected by the internal pressure during an event. Although the expansion rate of the case 120 is low because the metal layer 120b is made of steel or stainless steel having a plating formed on its surface, the exhaust port 129 may be located at approximately the center of the second sealing portion 126b that is most affected by the internal pressure to facilitate the rupture of the exhaust port 129. In Figure 7 it, when the first sealing portion 126a is located on the upper side, the exhaust port 129 is shown as being located in the second sealing portion 126b on the right side, but the exhaust port may be located in the second sealing portion 126b on the left side.

[0073] The exhaust port 129 may be a cut (e.g., notch) made substantially perpendicular to the edge of the sealing portion 126. The exhaust port 129 may be perpendicular (or substantially perpendicular) to the direction in which the sealing portion 126 extends. Due to the cut, the portion of the sealing portion 126 provided with the exhaust port 129 may have a lower bonding force (which is generated due to fusion) between the housing cover 122 and the housing body 121 than the remaining portion of the sealing portion 126. The length b of the exhaust port 129 may not exceed approximately 50% of the width a of the sealing portion 126 in the y direction. The width c of the sealing portion 126 in the portion provided with the exhaust port 129 may be less than the width a of the sealing portion 126 in the remaining portion of the sealing portion 126. The width c of the sealing portion 126 in the portion provided with the exhaust port 129 may be at least approximately 50% of the width a of the sealing portion 126 in the remaining portion of the sealing portion 126. In one or more embodiments, the exhaust port 129 may include a cut (e.g., notch) oriented at an angle with respect to the extending direction of the sealing portion 126.

[0074] The exhaust port 129 may be formed by cutting the sealing portion 126 of the housing 120 using a general cutting device after the sealing portion 126 is fused. The exhaust port 129 may include an adhesive or a UV curable material so as to prevent (or at least mitigate) moisture from penetrating into the exposed metal layer 120b after a part of the sealing portion 126 is cut. In one or more embodiments, in the portion of the sealing portion 126 provided with the exhaust port 129, the hot fusion layer located at this portion of the sealing portion 126 of the housing 120 may have a fusion pattern having a smaller width than the fusion pattern of the hot fusion layer of the remaining portion of the sealing portion 126. This portion of the sealing portion 126 may have a lower bonding force between the housing cover 122 and the housing body 121 due to the fusion pattern.

[0075] In one or more embodiments, as Figure 8 shown, in the secondary battery 100, the exhaust port 129 may be located substantially at the center of the first sealing portion 126a in the second direction y. The exhaust port 129 may be located between the positive electrode lead tab 130 and the negative electrode lead tab 140 in the first sealing portion 126a. The exhaust port 129 may be located between the positive electrode lead tab 130 and the negative electrode lead tab 140, and the positive electrode lead tab 130 and the negative electrode lead tab 140 are most vulnerable to deterioration in the sealing portion 126 and may therefore be more vulnerable to increased internal pressure. The shape and structure of the exhaust port 129 may be similar to the shape and structure of the previously described exhaust port 129. However, the difference is that the exhaust port 129 is provided in one of the first sealing portion 126a instead of the second sealing portion 126b.

[0076] In one or more embodiments, as Figure 9 shown, the vent 129 may be located in each of the first sealing portion 126a and the second sealing portion 126b of the secondary battery 100. A plurality of vents 129 may be provided in the secondary battery 100. The vent 129 may include a first vent 129a and a second vent 129b. The first vent 129a is substantially located at the center of the first sealing portion 126a in the second direction y, and the center of the first sealing portion 126a is most affected by the internal pressure of the housing 120. The second vent 129b is substantially located at the center of the second sealing portion 126b in the first direction x. In the secondary battery 100, depending on the type and location of the event occurring in the housing 120, the vent 129 among the plurality of vents 129 that is more affected by the internal pressure may be opened first. The first vent 129a may be configured similarly to the vent Figure 8 shown, and the second vent 129b may be configured similarly to the vent Figure 7 shown.

[0077] In one or more embodiments, as Figure 10 and Figure 11 shown, the vent 129 may be spaced apart from the center of the second sealing portion 126b (which is more affected by the internal pressure of the housing 120 of the secondary battery 100) in the first direction x. The vent 129 may be located between the center of the second sealing portion 126b and the folding portion 124. If the housing 120 further expands such that the internal pressure is greater than the internal pressure that causes the vent to open when the vent is located at the center of the second sealing portion 126b, the vent 129 may open. If the vent is positioned closer to the center of the second sealing portion 126b (as Figure 11 shown), the vent 129 may open at a lower internal pressure than when the vent is positioned closer to the folding portion 124 (as Figure 10 shown). The position of the vent 129 may be varied in various ways to control the time when the vent 129 opens after an increase in internal pressure occurs. However, as Figure 7 shown, if the vent is located at the center of the second sealing portion 126b, the vent 129 may open the fastest, which may improve stability. In Figure 10 and Figure 11 when the first sealing portion 126a is located on the upper side, the vent 129 is shown to be located in the second sealing portion 126b on the right side, but the vent may be located on the second sealing portion 126b on the left side.

[0078] It is apparent from the above description that in a secondary battery according to various embodiments of the present disclosure, an exhaust port can be provided in a sealing portion such that a portion of the sealing portion provided with the exhaust port has a low bonding force (the bonding force is generated due to fusion) between the case lid and the case body, so that if the secondary battery made of steel or stainless steel (SUS) having a plating formed on its surface expands due to internal pressure, the exhaust port is easily broken, thereby improving safety.

[0079] The effects of the present disclosure are not limited to those described above, and from the above description of the exemplary embodiments, other technical effects not mentioned will be apparent to those skilled in the art.

[0080] The above is only one embodiment for implementing the secondary battery according to the present disclosure. The present disclosure is not limited to the above embodiment, and the technical spirit of the present disclosure reaches the extent that any ordinary person skilled in the art to which the present disclosure pertains can make various modifications without departing from the gist of the present disclosure claimed in the appended claims.

[0081] This application claims the priority and benefits of Korean Patent Application No. 10-2023-0184087, filed with the Korean Intellectual Property Office on December 18, 2023, the entire disclosure of which is incorporated herein by reference.

Claims

1. A secondary battery comprising: An electrode assembly, comprising a positive electrode plate, a negative electrode plate, and a separator between the positive electrode plate and the negative electrode plate; as well as a shell configured to accommodate the electrode assembly, the shell comprising a metal layer, wherein the housing comprises sealing portions sealed by fusion on at least three sides of the housing, and The sealing portion includes at least one exhaust port. 2 . The secondary battery according to claim 1 , wherein the metal layer comprises steel or stainless steel having a plating layer. 3 . The secondary battery according to claim 1 , wherein the vent is substantially at the center of the sealing portion.

4. The secondary battery according to claim 1, comprising: a positive electrode lead tab coupled to and electrically connected to the positive electrode plate of the electrode assembly, a portion of the positive electrode lead tab being exposed outside the case; as well as a negative electrode lead tab coupled to and electrically connected to the negative electrode plate of the electrode assembly, a portion of the negative electrode lead tab being exposed outside the case, The positive electrode lead tab and the negative electrode lead tab are exposed to the outside of the case from one side of the case, and the sealing portion is located at the one side of the case. 5 . The secondary battery according to claim 4 , wherein the exhaust port is between the positive electrode lead tab and the negative electrode lead tab.

6. The secondary battery according to claim 4, wherein the sealing portion comprises: a first sealing portion extending in a second direction, the second direction being a width direction of the case, the first sealing portion being on a side of the case from which the positive electrode lead tab and the negative electrode lead tab are exposed; as well as Two second sealing portions extend from one end of the first sealing portion and the other end of the first sealing portion in a first direction, the other end of the first sealing portion being opposite to the one end, and the first direction is a longitudinal direction of the housing. 7 . The secondary battery according to claim 6 , wherein the vent is substantially at the center of the first seal portion or substantially at the center of any one of the second seal portions. 8 . The secondary battery according to claim 6 , wherein the vent is substantially at a center of the second sealing portion in the first direction. 9 . The secondary battery according to claim 6 , wherein the vent is substantially at a center of the first sealing portion in the second direction. 10 . The secondary battery according to claim 6 , wherein the vent is spaced apart from a center of the second sealing portion in the first direction. 11 . The secondary battery according to claim 1 , wherein the vent comprises a notch in an edge of the sealing portion. 12 . The secondary battery according to claim 11 , wherein the notch of the vent is covered with an adhesive or a UV curable material. 13 . The secondary battery according to claim 11 , wherein the notch of the vent is substantially perpendicular to the edge or has a predetermined angle with the edge. 14 . The secondary battery according to claim 11 , wherein a width of the sealing portion in a portion where the vent is located is at least 50% of a width of the sealing portion in a remaining portion of the sealing portion. 15 . The secondary battery according to claim 1 , wherein the pattern of the heat fusion layer of the sealing portion has a smaller width at a portion where the vent is located than at a remaining portion of the sealing portion.

16. The secondary battery according to claim 1, wherein The housing comprises: a housing body including a recess and an extension portion, the recess being configured to accommodate the electrode assembly, the extension portion extending in an outward direction from the recess; as well as a housing cover joined to the extended portion of the housing body by fusion welding, and The sealing portion is a portion where the extending portion and the housing cover are bonded to each other by the fusion welding.

17. A secondary battery according to claim 16, wherein each of the shell body and the shell cover has a multilayer structure including a stack, the stack including an inner layer, a metal layer and an outer layer, the inner layer including an insulating heat-fused layer, the metal layer including steel or stainless steel with a coating, and the outer layer including an insulating material. 18 . The secondary battery according to claim 1 , wherein the vent includes a plurality of vents in the sealing portion.

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