Electrode, electrode assembly, and secondary battery

Abstract

An electrode according to an embodiment of the present invention may comprise: a sheet part; and a tab part protruding from the sheet part and disposed closer to one side of the sheet part in the width direction. The edge of the tab part may include: an end line located at the outermost side of the tab part; a first side line located on one side of the tab part in the width direction; a second side line located on the other side of the tab part in the width direction; a first connection line connecting the first side line and the sheet part; and a second connection line connecting the second side line and the sheet part and longer than the first connection line.

Description

Electrodes, electrode assemblies and secondary batteries

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0082648, filed June 25, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to an electrode having a tab portion, an electrode assembly including a plurality of the electrodes, and a secondary battery in which the electrode assembly is accommodated in an outer material.

[0005] In recent years, rising energy prices due to the depletion of fossil fuels and growing concerns about environmental pollution have made the demand for eco-friendly alternative energy sources essential for future living. Research is continuing into various power generation technologies, such as solar, wind, and tidal power. Furthermore, significant interest is being focused on power storage devices, such as batteries, to more efficiently utilize the generated electricity.

[0006] Moreover, with the development of technology and increasing demand for electronic mobile devices and electric vehicles that use secondary batteries, the demand for secondary batteries as an energy source is rapidly increasing, and accordingly, much research is being conducted on secondary batteries that can meet various needs.

[0007] Secondary batteries can be classified into cylindrical secondary batteries, pouch-type secondary batteries, and square secondary batteries depending on the shape of the outer packaging material. Among them, a pouch-type secondary battery can accommodate an electrode assembly in which a positive electrode, a negative electrode, a separator, etc. are laminated inside a pouch-type outer packaging material. The electrode assembly can be manufactured in various types, such as a stack type, a jelly roll type, and a stack-and-fold type. The electrode assembly can include electrodes and separators that are alternately interposed. In particular, the electrode may be provided with a tab portion to which an electrode lead is connected.

[0008] Recently, secondary batteries are being designed with longer and thicker electrodes to increase energy density, driven by the trend toward higher capacity and higher output. However, conventional electrodes suffer from a bottleneck phenomenon, where heat and stress are concentrated in specific areas due to the narrow tab width relative to the electrode itself. In particular, high heat generated in specific areas can trigger electrolyte decomposition and electrode assembly degradation, limiting the application of high currents.

[0009] The problem to be solved by the present invention is to provide an electrode capable of applying a high current and relieving stress concentration, and an electrode assembly and a secondary battery including the electrode.

[0010] An electrode according to an embodiment of the present invention may include a sheet portion; and a tab portion protruding from the sheet portion and positioned closer to one side in the width direction of the sheet portion. An edge of the tab portion may include an end line positioned at the outermost side of the tab portion; a first side line positioned at one side in the width direction of the tab portion; a second side line positioned at the other side in the width direction of the tab portion; a first connection line connecting the first side line and the sheet portion; and a second connection line connecting the second side line and the sheet portion and being longer than the first connection line.

[0011] The first connecting line and the second connecting line may include at least one of an arc shape having a constant radius of curvature, a curved shape having a variable radius of curvature along the extension direction, or a straight shape oblique to the end line.

[0012] The length of the first side line and the second side line may be 20% or more of the distance between the edge of the sheet portion and the end line.

[0013] The edge of the tab portion may further include a first arc line connecting the end line and the first side line; and a second arc line connecting the end line and the second side line. The respective radii of curvature of the first arc line and the second arc line may be the same.

[0014] The first connecting line and the second connecting line may include an arc shape having a radius of curvature greater than the radius of curvature of the first arc line and the second arc line.

[0015] The length of the first side line may be greater than the length of the second side line.

[0016] A virtual reference line extending from an edge of the sheet portion, a first virtual side line extending from the first side line, a second virtual side line extending from the second side line, a first virtual arc line connecting the virtual reference line and the first virtual side line and having the same radius of curvature as the radius of curvature of the first arc line, and a second virtual arc line connecting the virtual reference line and the second virtual side line and having the same radius of curvature as the radius of curvature of the second arc line can be defined. The tab portion can include a basic area surrounded by the end line, the first and second arc lines, the first and second side lines, the first and second virtual side lines, the first and second virtual arc lines, and the virtual reference line; a first extended area surrounded by the first connecting line, the virtual reference line, the first virtual side line, and the first virtual arc line; and a second extended area surrounded by the second connecting line, the virtual reference line, the second virtual side line, and the second virtual arc line.

[0017] The sum of the areas of the first extended area and the second extended area may be 3% to 40% of the area of ​​the basic area.

[0018] An electrode assembly according to an embodiment of the present invention may include a plurality of electrodes; and a separator interposed between the plurality of electrodes. The electrode may include a sheet portion; and a tab portion protruding from the sheet portion and positioned closer to one side in the width direction of the sheet portion. An edge of the tab portion may include an end line positioned at the outermost end of the tab portion; a first side line positioned at one side in the width direction of the tab portion; a second side line positioned at the other side in the width direction of the tab portion; a first connection line connecting the first side line and the sheet portion; and a second connection line connecting the second side line and the sheet portion and being longer than the first connection line.

[0019] The electrode assembly may further include an electrode lead welded to the tab portion; and a cover member covering a weld portion where the electrode lead and the tab portion are welded to each other. The cover member may cover at least a portion of the first connection line and the second connection line.

[0020] With respect to the protrusion direction of the tab portion, the distance between the outer end of the weld portion and the outer end of the first connection line and the distance between the outer end of the weld portion and the outer end of the second connection line may be 20% or less of the protrusion length of the tab portion.

[0021] A secondary battery according to an embodiment of the present invention may include an electrode assembly including a plurality of electrodes and a separator interposed between the plurality of electrodes; and an outer material including a receiving portion for receiving the electrode assembly and a sealing portion positioned around the receiving portion. The electrode may include a sheet portion; and a tab portion protruding from the sheet portion and positioned closer to one side in the width direction of the sheet portion. An edge of the tab portion may include an end line positioned at the outermost end of the tab portion; a first side line positioned at one side in the width direction of the tab portion; a second side line positioned at the other side in the width direction of the tab portion; a first connection line connecting the first side line and the sheet portion; and a second connection line connecting the second side line and the sheet portion and being longer than the first connection line.

[0022] The first connection line and the second connection line may be arranged at a distance of 2.5 mm or more from the sealing portion of the outer material.

[0023] According to a preferred embodiment of the present invention, the tab portion may further include extended areas on both sides compared to conventional tab portions. Accordingly, the width of the sheet portion of the tab portion may be increased, and its area may be increased. This may improve the heat dissipation performance of the tab portion, and allow for the application of a higher current than before. In other words, there is an advantage in that the Quick Charge (QC) time through the application of a high current to the electrode may be shortened, and output may be improved.

[0024] In addition, the configurations according to preferred embodiments of the present invention may include effects that can be easily predicted by those skilled in the art.

[0025] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0026] Figure 1 is a perspective view of a secondary battery according to one embodiment of the present invention.

[0027] Figure 2 is a cross-sectional view taken along line A-A' of Figure 1.

[0028] Figure 3 is a plan view of an electrode assembly according to one embodiment of the present invention.

[0029] Figure 4 is a plan view showing an enlarged view of the area around the tab portion of an electrode according to one embodiment of the present invention.

[0030] Fig. 5 is a plan view showing the electrode lead welded to the tab portion of Fig. 4 passing through the sealing portion of the outer material.

[0031] Figure 6 is an enlarged plan view showing the area around the tab portion of an electrode according to another embodiment of the present invention.

[0032] Figure 7 is an enlarged plan view showing the area around the tab portion of an electrode according to another embodiment of the present invention.

[0033] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0034] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0035] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0036] In the drawing, each component of a secondary battery according to one embodiment of the present invention is schematically illustrated, and the size of the component or the thickness of the line may be expressed somewhat exaggerated for the convenience of understanding.

[0037] FIG. 1 is a perspective view of a secondary battery according to one embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line A-A' of FIG. 1, and FIG. 3 is a plan view of an electrode assembly according to one embodiment of the present invention.

[0038] A secondary battery (1) may include an outer case (10) and an electrode assembly (20) accommodated in the outer case (10).

[0039] The outer material (10) may be manufactured by molding a laminate film. More specifically, the outer material (10) may include a receiving portion (11) in which an electrode assembly (20) is received, and a sealing portion (12) positioned around the receiving portion (11). The receiving portion (11) may have a sunken shape. The receiving portion (11) may be similar to a cup shape and may thus be referred to as a cup portion.

[0040] The outer case (10) may include a pair of cases, at least one of which has a recessed housing (11) formed therein. The pair of cases may face each other with the electrode assembly (20) interposed therebetween, and the peripheral portion of the housing (11) may be sealed by heat fusion to form a sealing portion (12). The pair of cases may be connected at one end by a folding portion, or may be separate cases separated from each other. Since this is a well-known technique, a detailed description thereof will be omitted.

[0041] The electrode assembly (20) may include a plurality of electrodes (100) and a separator (200) interposed between the plurality of electrodes (100) (see FIG. 5). More specifically, the electrode assembly (20) may include a plurality of electrodes (100) and a separator (200) interposed between the plurality of electrodes to mutually insulate the plurality of electrodes (100). The electrode assembly (20) may be accommodated in the housing (11) of the outer material (10) together with an electrolyte.

[0042] The electrode assembly (20) may be of a stack type, a jelly roll type, a stack and folding type, etc., and the type of the electrode assembly (20) is not limited.

[0043] Each of the plurality of electrodes (100) included in the electrode assembly (20) may be provided with a tab portion (120). The tab portion (120) may act as a path through which electrons can move between the inside and the outside of the electrode assembly (20).

[0044] A plurality of tab portions (120) of a plurality of electrodes (100) can be welded together, and this process can be referred to as pre-welding. Pre-welding can be performed by ultrasonic welding, laser welding, or resistance welding.

[0045] More specifically, the electrode assembly (20) may include a plurality of positive electrode tabs joined to each other and a plurality of negative electrode tabs joined to each other. The positive electrode tabs and the negative electrode tabs may protrude in different directions from the electrode assembly (20), but are not limited thereto and may be formed to protrude in various directions, such as protruding in parallel in the same direction from one side.

[0046] The electrode assembly (20) may include a plurality of tab portions (120) and welded electrode leads (130). The electrode leads (130), together with the tab portions (120), may act as a path for current to flow between the electrode assembly (20) and an external load.

[0047] More specifically, the electrode assembly (20) may include a plurality of positive tabs and a welded positive lead, and a plurality of negative tabs and a welded negative lead. The positive leads and negative leads may protrude from the electrode assembly (20) in different directions, or may protrude in parallel in the same direction, depending on the protruding positions of the positive tabs and negative tabs.

[0048] The electrode lead (130) may protrude to the outside through the sealing portion (12) of the outer material (10). More specifically, the outer end of the electrode lead (130) may be located on the outside of the outer material (10), and the inner end of the electrode lead (130) may be welded to the tab portion (120).

[0049] The electrode lead (130) may be welded to the outermost tab portion (120) among the plurality of tab portions (120). That is, the electrode lead (130) may be welded to one of the thickness-wise surfaces of the pre-welded portion in which the plurality of tab portions (120) are welded to each other. However, this is not limited thereto, and it is also possible for the electrode lead (130) to be welded between some of the plurality of tab portions (120) and other parts.

[0050] The process of welding the electrode lead (130) and the plurality of tab portions (120) can be called main welding. Main welding can be performed by ultrasonic welding, laser welding, or resistance welding.

[0051] The welded portion (131) where the plurality of tab portions (120) and electrode leads (130) are welded to each other may be surrounded by a cover member (140). The welded portion (131) may be a portion where the plurality of tab portions (120) are welded to each other.

[0052] The cover member (140) may have an insulating material. For example, the cover member (140) may be an insulating tape.

[0053] A portion of the electrode lead (130) may be surrounded by an insulating member (150). The insulating member (150) may be positioned outside the cover member (140) with respect to the length direction of the electrode lead (130).

[0054] The insulating member (150) can surround a portion of the electrode lead (130) at a position corresponding to the sealing portion (12) and can be thermally bonded to the inner surface of the sealing portion (12). As a result, the electrode lead (130) and the outer material (10) can be insulated from each other while the sealing of the sealing portion (12) is maintained by the insulating member (150).

[0055] This insulating member (150) can be manufactured from a non-conductive insulator that does not conduct electricity well. Generally, as the insulating member (150), an insulating tape that is easy to attach to the electrode lead (130) and has a relatively thin thickness is widely used. However, the present invention is not limited thereto and various materials can be used as long as they can insulate the electrode lead (130).

[0056] FIG. 4 is a plan view showing an enlarged view of the area around the tab portion of an electrode according to one embodiment of the present invention, and FIG. 5 is a plan view showing an electrode lead welded to the tab portion of FIG. 4 passing through a sealing portion of an outer material.

[0057] An electrode (100) according to one embodiment of the present invention may include a sheet portion (110) and a tab portion (120).

[0058] The electrode (100) may be an anode or a cathode.

[0059] The sheet portion (110) can be formed by laminating a composite layer on a current collector. That is, the sheet portion (110) can be a holding portion of the electrode (100). The detailed materials and composition of the current collector and the composite layer are well known in the art, so a detailed description thereof will be omitted.

[0060] The sheet portion (110) may have a sheet shape with a predetermined width and length.

[0061] The tab portion (120) can protrude from the sheet portion (110). The function of the tab portion (120) is described above.

[0062] The edge of the tab (120) may include an end line (121), a first side line (122a), and a second side line (122b).

[0063] The end line (121) may be located at the outermost side of the tab portion (120). That is, the end line (121) may be the edge of the most protruding part of the tab portion (120). The end line (121) may be a straight line parallel to the edge (111) of the sheet portion (110).

[0064] Both side lines (122a)(122b) may be located on both sides in the width direction of the tab portion (120). More specifically, the first side line (122a) may be located on one side in the width direction of the tab portion (120), and the second side line (122b) may be located on the other side in the width direction of the tab portion (120). Both side lines (122a)(122b) may be straight lines perpendicular to the edge (111) of the sheet portion (110).

[0065] The edge of the tab (120) may further include a first arc line (124a) and a second arc line (124b).

[0066] The first arc line (124a) may connect the end line (121) and the first side line (122a). The second arc line (124b) may connect the end line (121) and the second side line (122b). Each arc line (124a) (124b) may be a curve having a constant radius of curvature. The respective radii of curvature of the first arc line (124a) and the second arc line (124a) may be the same.

[0067] The edge of the tab (120) may include a first connection line (123a) and a second connection line (123b).

[0068] The first connection line (123a) can connect the first side line (122a) and the sheet portion (110). More specifically, the first connection line (123a) can connect the first side line (122a) and the edge (111) of the sheet portion (110).

[0069] The second connection line (123b) can connect the second side line (122b) and the sheet portion (110). More specifically, the second connection line (123b) can connect the second side line (122b) and the edge (111) of the sheet portion (110).

[0070] In the present embodiment, the first connection line (123a) and the second connection line (123b) may include a curved shape with a variable radius of curvature along the direction of extension. In other words, each connection line (123a) (123b) may include a concave curved shape with an irregular curvature.

[0071] Conventional electrodes typically have the two side lines of the tab portion and the edge of the sheet portion connected to each other by connecting lines having a constant radius of curvature. For example, each virtual arc line (V3a) (V3b) illustrated in Fig. 4 may correspond to a connecting line of a conventional electrode and may have a constant radius of curvature.

[0072] On the other hand, the first connection line (123a) and the second connection line (123b) according to the present embodiment may be positioned further outward than each virtual arc line (V3a) (V3b), and the radius of curvature may be variable along the extension direction.

[0073] By this configuration, the tab portion (120) according to the present embodiment can further include extended areas (A2) (A3) on both sides compared to the conventional tab portion. Accordingly, the width of the sheet portion (110) side of the tab portion (120) can be widened, and the area can be increased. As a result, the heat dissipation performance of the tab portion (120) can be improved, and a higher current can be applied than before. That is, there is an advantage in that the Quick Charge (QC) time can be shortened through the application of a high current to the electrode (100), and the output can be improved.

[0074] In more detail, the tab section (120) may include a base area (A1), a first extended area (A2), and a second extended area (A3). To clearly define each area (A1) (A2) (A3), a virtual reference line (V1), a first virtual side line (V2a), a second virtual side line (V2b), a first virtual arc line (V3a), and a second virtual arc line (V3b) may be defined.

[0075] The virtual reference line (V1) may extend from the edge (111) of the sheet portion (110). That is, the virtual reference line (V1) may be a straight line positioned on the same line as the edge (111) of the sheet portion (110).

[0076] The first virtual side line (V2a) may extend from the first side line (122a), and the second virtual side line (V2b) may extend from the second side line (122b). That is, each virtual side line (V2a) (V2b) may be a straight line located on the same line as each side line (122a) (122b).

[0077] The first virtual arc line (V3a) can connect the virtual reference line (V1) and the first virtual side line (V2a), and the second virtual arc line (V3b) can connect the virtual reference line (V1) and the second virtual side line (V2b). Each virtual arc line (V3a) (V3b) can be a curve having a constant radius of curvature. The first virtual arc line (V3a) can have a radius of curvature that is the same as the radius of curvature of the first arc line (124a), and the second virtual arc line (V3b) can have a radius of curvature that is the same as the radius of curvature of the second arc line (124b).

[0078] The basic area (A1) of the tab portion (120) may be an area corresponding to the existing tab portion. More specifically, the basic area (A1) may be an area surrounded by an end line (121), first and second arc lines (124a) (124b), first and second side lines (122a) (122b), first and second virtual side lines (V2a) (V2b), first and second virtual arc lines (V3a) (V3b), and a virtual reference line (V1).

[0079] The first and second expansion areas (A2) (A3) of the tap portion (120) may be expanded areas compared to the existing tap portion. More specifically, the first expansion area (A2) of the tap portion (120) may be an area surrounded by a first connection line (123a), a virtual reference line (V1), a first virtual side line (V2a), and a first virtual arc line (V3a). The second expansion area (A3) of the tap portion (120) may be an area surrounded by a second connection line (123b), a virtual reference line (V1), a second virtual side line (V2b), and a second virtual arc line (V3b).

[0080] As described above, the heat dissipation performance of the tab portion (120) can be improved by the first and second expansion areas (A2) (A3), and a higher current can be applied than before.

[0081] The sum of the areas of the first expansion area (A2) and the second expansion area (A3) (hereinafter, “expansion area”) may be 3% to 40% of the area of ​​the basic area (A1). If the expansion area is less than 3% of the area of ​​the basic area (A1), the improvement in performance may be somewhat minimal. If the expansion area is greater than 40% of the area of ​​the basic area (A1), there is a concern that the expansion areas (A2)(A3) may interfere with the sealing portion (12) of the exterior material (10).

[0082] Meanwhile, the tab portion (120) may be arranged closer to one side in the width direction of the sheet portion (110). More specifically, the distance (d1) between one edge in the width direction of the sheet portion (110) and the first side line (122a) may be closer than the distance (d2) between the other edge in the width direction of the sheet portion (110) and the second side line (122b). Here, the second connection line (123b) of the tab portion (120) may be longer than the first connection line (123a). That is, the area of ​​the second expansion area (A3) may be wider than the area of ​​the first expansion area (A2).

[0083] In this way, the area of ​​the tab portion (120) can be secured widely while maintaining the length of each side line (122a) (122b) at a certain level.

[0084] The length (d4) of the first side line (122a) may be greater than or equal to the length (d5) of the second side line (122b). As described above, since the area of ​​the second extended area (A3) is greater than that of the first extended area (A2), even if the length (d5) of the second side line (122b) is less than or equal to the length (d4) of the first side line (122a), the area of ​​the second extended area (A3) can be secured to a certain level or greater. FIG. 4 illustrates an embodiment in which the length (d4) of the first side line (122a) and the length (d5) of the second side line (122b) are equal to each other.

[0085] The first side line (122a) and the second side line (122b) may have a length (d4) (d5) that forms a predetermined straight section.

[0086] In this regard, the manufacturing process of the electrode assembly (20) may include a process of laminating the electrode (100) and the separator (200), and a process of inspecting the meandering of the electrode (100) with respect to the separator (200). The sensor inspecting the meandering of the electrode (100) may perform the inspection based on the edge of the electrode (100). Therefore, the longer and more straight sections there are at the edge of the electrode (100), the more accurate the inspection can be. That is, when the first and second side lines (122a) (122b) have a predetermined length (d4) (d5), the accuracy of the meandering inspection for the electrode (100) can be improved.

[0087] In more detail, the length (d4) of the first side line (122a) and the length (d5) of the second side line (122b) may be 20% or more of the distance (d3) between the edge (111) of the sheet portion (110) and the end line (121) of the tab portion (120). If the lengths (d4) and (d5) of the first and second side lines (122a) (122b) are less than 20% of the distance (d3), the precision of the meandering inspection for the electrode (100) may be somewhat reduced.

[0088] As an experimental example, an analysis simulation was performed while varying the length (d4)(d5) of the side line (122a)(122b). In the case of the cathode, when the length (d4)(d5) of the side line (122a)(122b) was 4.5 mm, the stress at the notch was measured as 23.0 MPa and the stress at the weld was measured as 70.6 MPa, and when the length (d4)(d5) of the side line (122a)(122b) was 8 mm, the stress at the notch was measured as 50.8 MPa and the stress at the weld was measured as 60.5 MPa. In the case of the anode, when the length (d4)(d5) of the side line (122a)(122b) is 4.5 mm, the notched stress is measured as 35.0 Mpa and the weld stress is measured as 113.9 Mpa, and when the length (d4)(d5) of the side line (122a)(122b) is 8 mm, the notched stress is measured as 64.6 Mpa and the weld stress is measured as 98.2 Mpa. Here, the notched stress may mean the stress measured at the boundary between the side line (122a)(122b) of the tab part (120) and the connecting line (123a)(123b). In addition, the weld stress may mean the stress measured at the end of the weld part (131) in which a plurality of tab parts (120) are welded to each other.

[0089] That is, it can be confirmed that when the length (d4)(d5) of the side line (122a)(122b) is shortened, the notching stress decreases and the welding stress increases. Therefore, in order to prevent the notching stress and the welding stress from becoming excessively high, the length (d4)(d5) of the side line (122a)(122b) can be appropriately selected within the range of 4.5 mm to 8 mm.

[0090] Meanwhile, as described above, the cover member (140) can cover the welded portion (131) where a plurality of tab portions (120) and electrode leads (130) are welded to each other.

[0091] Here, the cover member (140) can cover at least a portion of the first connection line (123a) and the second connection line (123b) of the tab portion (120). For example, as illustrated in FIG. 5, the cover member (140) can cover a portion of the electrode lead (130) side of each connection line (123a) (123b). Accordingly, the cover member (140) can alleviate the notched portion stress applied to the tab portion (120), and can prevent a short circuit from occurring at the boundary between the side line (122a) (122b) and the connection line (123a) (123b) due to the notched portion stress.

[0092] Meanwhile, the outer end of the connecting line (123a)(123b) may be located within a predetermined distance from the welding part (131). The outer end of the connecting line (123a)(123b) may mean the boundary between the connecting line (123a)(123b) and the side line (122a)(122b).

[0093] In more detail, with respect to the protrusion direction of the tab portion (120), the distance (d6) between the outer end of the weld portion (131) and the outer end of the first and second connection lines (123a), and the distance (d7) between the outer end of the weld portion (131) and the outer end of the second connection line (123b), may be 20% or less of the protrusion length (d3) of the tab portion (120). The protrusion length (d3) of the tab portion (120) may be the distance between the edge (111) of the sheet portion (110) and the end line (121) of the tab portion (120).

[0094] Accordingly, since the length (d4)(d5) of the side line (122a)(122b) of the tab portion (120) is formed to be short at a certain level, the stress at the notching portion can be kept relatively low, and the occurrence of a short circuit from the edge of the tab portion (120) can be prevented. In addition, a cover member (140) having an appropriate size can easily cover the outer ends of the welding portion (131) and the connecting line (123a)(123b) together.

[0095] Meanwhile, in order to prevent the tab portion (120), particularly the extended area (A2) (A3) of the tab portion (120), from interfering with the sealing portion (12) of the exterior material (10), the first and second connection lines (123a) (123b) of the tab portion (120) may be arranged at a predetermined distance from the sealing portion (120) of the exterior material (10). Preferably, the first and second connection lines (123a) (123b) may be arranged at a distance of 2.5 mm or more from the sealing portion (120) of the exterior material (10).

[0096] The sealing portion (12) may be formed long along the perimeter of the outer material. The first and second connection lines (123a) (123b) may be positioned at a distance of 2.5 mm or more from the sealing portion (120) along the entire length of the sealing portion (12).

[0097] In this way, the tab portion (120) is prevented from interfering with the sealing portion (12) of the outer material (10), and the sealing portion (12) can be formed reliably.

[0098] FIG. 6 is an enlarged plan view illustrating the area around a tab portion of an electrode according to another embodiment of the present invention, and FIG. 7 is an enlarged plan view illustrating the area around a tab portion of an electrode according to another embodiment of the present invention.

[0099] Below, explanations that overlap with the previously explained content will be cited, and explanations will be focused on the differences.

[0100] The first and second connecting lines (123a)(123b) can be formed to have various shapes.

[0101] For example, referring to FIG. 6, the first and second connecting lines (123a) (123b) may have an arc shape with a constant radius of curvature. The first and second connecting lines (123a) (123b) may have a concave arc shape. More specifically, the first connecting line (123a) and the second connecting line (123b) may include an arc shape with a radius of curvature greater than the radius of curvature of the first arc line (124a) and the second arc line (124b).

[0102] As another example, referring to FIG. 7, the first and second connection lines (123a) (123b) may have a straight shape oblique to the end line (121).

[0103] However, it is not limited thereto, and the first and second connecting lines (123a) (123b) may be appropriately combined with the embodiments described above. That is, the first and second connecting lines (123a) (123b) may include at least one of an arc shape having a constant radius of curvature (Fig. 6), a curved shape having a variable radius of curvature along the extension direction (Fig. 4), or a straight shape oblique to the end line (Fig. 7).

[0104] Meanwhile, as previously described, the length (d4) of the first side line (122a) may be longer than the length (d5) of the second side line (122b). FIG. 6 illustrates an embodiment in which the length (d4) of the first side line (122a) is longer than the length (d5) of the second side line (122b), and FIG. 7 illustrates an embodiment in which the length (d4) of the first side line (122a) and the length (d5) of the second side line (122b) are the same.

[0105] The above description is merely an example of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention.

[0106] Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of ​​the present invention but to explain it, and the scope of the technical idea of ​​the present invention is not limited by these embodiments.

[0107] The scope of protection of the present invention should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

[0108] [Explanation of symbols]

[0109] 1: Secondary battery 10: Exterior material

[0110] 11: Storage section 12: Sealing section

[0111] 20: Electrode assembly 100: Electrode

[0112] 110: Seat 111: Edge (of seat)

[0113] 120: Tap section 121: End line

[0114] 122a: 1st side line 122b: 2nd side line

[0115] 123a: First connecting line 123b: Second connecting line

[0116] 124a: First arc line 124b: Second arc line

[0117] 130: Electrode lead 131: Welding part

[0118] 140: Cover member 150: Insulating member

[0119] 200: Membrane A1: Basic area

[0120] A2: First expansion area A3: Second expansion area

[0121] V1: Virtual reference line V2a: First virtual side line

[0122] V2b: Second virtual side line V3a: First virtual arc line

[0123] V3b: Second virtual arc line

Claims

1. Sheet part; and It includes a tab portion that protrudes from the sheet portion and is positioned closer to one side in the width direction of the sheet portion, The edge of the above tab is, End line located at the outermost side of the above tab; A first side line located on one side of the width direction of the above tab portion; A second side line located on the other side of the width direction of the above tab portion; A first connecting line connecting the first side line and the sheet portion; and An electrode including a second connection line that connects the second side line and the sheet portion and is longer than the first connection line.

2. In paragraph 1, The above first connection line and second connection line, An electrode comprising at least one of an arc shape having a constant radius of curvature, a curved shape having a variable radius of curvature along an extension direction, or a straight shape oblique to the end line.

3. In paragraph 1, An electrode in which the length of the first side line and the second side line is at least 20% of the distance between the edge of the sheet portion and the end line.

4. In paragraph 1, The edge of the above tab is, A first arc line connecting the end line and the first side line; and It further includes a second arc line connecting the end line and the second side line, The radius of curvature of each of the first and second arc lines is the same electrode.

5. In paragraph 4, The above first connection line and second connection line, An electrode including an arc shape having a radius of curvature greater than the radius of curvature of the first arc line and the second arc line.

6. In paragraph 1, An electrode in which the length of the first side line is greater than the length of the second side line.

7. In paragraph 4, When defining a virtual reference line extending from the edge of the sheet portion, a first virtual side line extending from the first side line, a second virtual side line extending from the second side line, a first virtual arc line connecting the virtual reference line and the first virtual side line and having a curvature radius equal to the curvature radius of the first arc line, and a second virtual arc line connecting the virtual reference line and the second virtual side line and having a curvature radius equal to the curvature radius of the second arc line, The above tab part, A basic area surrounded by the end line, the first and second arc lines, the first and second side lines, the first and second virtual side lines, the first and second virtual arc lines and the virtual reference line; a first extended area surrounded by the first connecting line, the virtual reference line, the first virtual side line, and the first virtual arc line; and An electrode comprising a second extension area surrounded by the second connecting line, the virtual reference line, the second virtual side line, and the second virtual arc line.

8. In paragraph 7, An electrode in which the sum of the areas of the first expansion region and the second expansion region is 3% to 40% of the area of ​​the basic region.

9. Multiple electrodes; and It includes a separator interposed between the plurality of electrodes, The above electrodes are, sheet; and It includes a tab portion that protrudes from the sheet portion and is positioned closer to one side in the width direction of the sheet portion, The edge of the above tab is, End line located at the outermost part of the above tab; A first side line located on one side of the width direction of the above tab portion; A second side line located on the other side of the width direction of the above tab portion; A first connecting line connecting the first side line and the sheet portion; and An electrode assembly including a second connection line that connects the second side line and the sheet portion and is longer than the first connection line.

10. In paragraph 9, Electrode leads welded to the above tab portion; and Further comprising a cover member covering a welded portion where the electrode lead and the tab portion are welded to each other, The above cover member is an electrode assembly that covers at least a portion of the first connection line and the second connection line.

11. In paragraph 10, An electrode assembly in which, with respect to the protrusion direction of the tab portion, the distance between the outer end of the weld portion and the outer end of the first connection line and the distance between the outer end of the weld portion and the outer end of the second connection line are 20% or less of the protrusion length of the tab portion.

12. An electrode assembly comprising a plurality of electrodes and a separator interposed between the plurality of electrodes; and It includes an outer material including a storage portion that accommodates the electrode assembly and a sealing portion located around the storage portion, The above electrodes are, sheet; and It includes a tab portion that protrudes from the sheet portion and is positioned closer to one side in the width direction of the sheet portion, The edge of the above tab is, End line located at the outermost part of the above tab; A first side line located on one side of the width direction of the above tab portion; A second side line located on the other side of the width direction of the above tab portion; A first connecting line connecting the first side line and the sheet portion; and A secondary battery including a second connection line that connects the second side line and the sheet portion and is longer than the first connection line.

13. In paragraph 12, The above first connection line and the second connection line are arranged at a distance of 2.5 mm or more from the sealing portion of the outer material.

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