Secondary battery, and Manufacturing method thereof

Abstract

The present invention relates to a secondary battery, and more specifically, to a secondary battery and a method for manufacturing the same, wherein the width of the electrode tab is formed wider than the width of the electrode lead, the electrode lead is inserted between the stacked electrode tabs, and the electrode lead, the electrode tab, and the remaining electrode tabs are each welded, or a coupling member is further provided on one side of the electrode lead and the coupling member is welded to the electrode lead and the electrode tabs, respectively, thereby preventing the electrode lead from being separated from the electrode tabs.

Description

Technology Field

[0001] The present invention relates to a secondary battery, and more specifically, to a secondary battery and a method for manufacturing the same, wherein the width of the electrode tab is formed wider than the width of the electrode lead, the electrode lead is inserted between the stacked electrode tabs, and the electrode lead, the electrode tab, and the remaining electrode tabs are each welded, or a coupling member is further provided on one side of the electrode lead and the coupling member is welded to the electrode lead and the electrode tabs, respectively, thereby preventing the electrode lead from being separated from the electrode tabs. Background Technology

[0002] Secondary batteries, which possess electrical characteristics such as high energy density and high applicability across product lines, are widely applied not only to portable devices but also to electric vehicles (EVs) or hybrid vehicles (HVs) driven by electric power sources.

[0003] Generally, a secondary battery is composed of an electrode assembly consisting of a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes, which is then embedded in a battery case made of a metal can or laminate sheet in a stacked or wound state, and then an electrolyte is injected or impregnated.

[0004] FIG. 1 is a schematic diagram showing the general structure of a conventional secondary battery. Referring to FIG. 1, a plurality of electrode tabs (5) are protruded from one end of the electrode assembly (3) to be electrically connected to an electrode lead (8). At this time, each electrode tab (5) is formed by extending in one direction from each electrode plate (4) of the electrode assembly (3), and the electrode tabs (5) are combined in a stacked structure and connected to the electrode lead (8). The electrode lead (8) is generally joined to the electrode tabs (5) by welding, and can be joined by being located on the upper or lower surface of the joined electrode tabs (5).

[0005] At this time, the following issues exist when welding the electrode leads and electrode tabs together.

[0006] First, regarding over-welding, there is a problem that the electrode tabs break when over-welded because the thickness of one electrode tab is very thin, ranging from a few μm to tens of μm.

[0007] Second, regarding the welding, in an electrode assembly with the structure described above, since welding for joining the electrode leads and electrode tabs proceeds only in one direction, there is a problem in that the electrode leads and electrode tabs easily separate when an external force is applied to the joined area. Prior art literature

[0008] Korean Published Patent Application No. 2017-0042134 (October 11, 2018) The problem to be solved

[0009] The present invention has been devised to solve the problems described above, and the purpose of the present invention is to provide a secondary battery capable of preventing the electrode lead from separating from the electrode tabs by forming the width of the electrode tab wider than the width of the electrode lead, inserting the electrode lead between the stacked electrode tabs, and welding the electrode lead, the electrode tab, and the remaining electrode tabs, respectively, or by further providing a coupling member on one side of the electrode lead and welding the coupling member to the electrode lead and the electrode tabs, respectively. means of solving the problem

[0010] A secondary battery according to one example of the present invention comprises: an electrode assembly; an electrode tab stacking portion in which electrode tabs protruding from one side of the electrode assembly are stacked; and an electrode lead that contacts at least one of the electrode tabs and is electrically connected to the electrode tabs; wherein the electrode tab stacking portion may be formed such that the width of the electrode tabs is wider than the width of the electrode lead, and may consist of an overlap portion that overlaps with the width of the electrode lead, and a remainder portion located on one or both sides in the width direction of the electrode lead that does not overlap with the width of the electrode lead.

[0011] The electrode lead can be inserted between the electrode tabs such that some of the electrode tabs located in the overlap portion are located on the upper part of the electrode lead and the remaining portion is located on the lower part of the electrode lead, and thus can be coupled with the electrode tabs located in the overlap portion.

[0012] The electrode tabs located in the above remaining portion can be combined with each other.

[0013] The electrode leads and the electrode tabs located in the overlap portion can be welded together through ultrasonic welding, and the electrode tabs located in the remaining portion can be welded together through laser welding.

[0014] The electrode lead has a tapered portion formed therein that becomes thinner from a certain point toward one end, and the tapered portion may be located between the electrode tabs.

[0015] A secondary battery according to another example of the present invention has the electrode lead in contact with the upper surface of an electrode tab located at the top of the electrode tab stacking portion or the lower surface of an electrode tab located at the bottom, and a coupling member may be further provided on the upper or lower portion of the electrode lead.

[0016] The above coupling member is formed such that the width of the coupling member is wider than the width of the electrode lead, so that the region of the coupling member corresponding to the electrode lead is coupled to the electrode lead, and the region of the coupling member corresponding to the remaining portion is coupled to the electrode tabs of the remaining portion.

[0017] The above-mentioned connecting member may be a plurality of metal foils stacked together.

[0018] The region of the above-mentioned coupling member corresponding to the electrode lead, the electrode lead, and the electrode tabs of the overlap portion can be welded together through ultrasonic welding, and the region of the above-mentioned coupling member corresponding to the remaining portion and the electrode tabs located in the remaining portion can be welded together through laser welding.

[0019] A method for manufacturing a secondary battery according to one example of the present invention comprises the step of preparing an electrode assembly;

[0020] The method comprises the steps of: forming an electrode tab stacking portion consisting of electrode tabs that protrude from one side of the electrode assembly and are stacked; and arranging an electrode lead to contact at least one of the electrode tabs; wherein the electrode tab stacking portion may be formed such that the width of the electrode tabs is wider than the width of the electrode lead, and may consist of an overlap portion that overlaps with the width of the electrode lead, and a remainder portion located on one or both sides in the width direction of the electrode lead that does not overlap with the width of the electrode lead.

[0021] In the step of arranging the electrode lead, the electrode lead can be inserted between the electrode tabs such that some of the electrode tabs located in the overlap portion are located on the upper part of the electrode lead and the remaining portions are located on the lower part of the electrode lead.

[0022] The method may further include the step of joining the electrode leads and the electrode tabs located in the overlap portion together, and joining the electrode tabs located in the remaining portion together.

[0023] The electrode leads and the electrode tabs located in the overlap portion can be welded together through ultrasonic welding, and the electrode tabs located in the remaining portion can be welded together through laser welding.

[0024] A method for manufacturing a secondary battery according to another example of the present invention may further include, in the step of arranging the electrode leads, arranging the electrode leads to contact the upper surface of an electrode tab located at the top of the electrode tab stacking portion or the lower surface of an electrode tab located at the bottom of the electrode tab stacking portion, and providing a coupling member on the upper or lower portion of the electrode leads.

[0025] The method may further include the step of joining the region of the joining member corresponding to the electrode lead, the electrode lead, and the electrode tabs of the overlap portion together, and joining the region of the joining member corresponding to the remainder and the electrode tabs of the remainder together.

[0026] The region of the above-mentioned coupling member corresponding to the electrode lead, the electrode lead, and the electrode tabs of the overlap portion can be welded together through ultrasonic welding, and the region of the above-mentioned coupling member corresponding to the remaining portion and the electrode tabs located in the remaining portion can be welded together through laser welding. Effects of the invention

[0027] According to the present invention, even if the welded portion between the electrode lead and the electrode tab is weak, the electrode lead can be supported by welding between the remaining electrode tabs formed on both sides of the electrode lead, thereby preventing the electrode lead from completely detaching from the electrode tab even if an external impact occurs, and accordingly, the electrical connectivity of the secondary battery can be improved.

[0028] Furthermore, unlike conventional methods, when welding electrode leads and electrode tabs together, the first welding is performed at the overlap portion and the second welding is performed at the remaining portion, rather than welding in a straight line at once on the upper or lower surface of the electrode lead. This prevents the electrode tabs from being completely severed even if over-welding occurs, thereby significantly reducing the defect rate during the production of secondary batteries. Brief explanation of the drawing

[0029] Figure 1 is a schematic diagram showing the general structure of a conventional secondary battery. FIG. 2 is a partial schematic diagram of a secondary battery according to an example of the present invention. Figure 3 is an exploded perspective view of Figure 2. Figure 4 is a top view of Figure 2. Figure 5 is another example of Figure 4. Fig. 6 is a side cross-sectional view of Fig. 2. FIG. 7 is a schematic diagram showing a side cross-section of an electrode lead and an electrode tab according to an example of the present invention. FIG. 8 is a partial schematic diagram of a secondary battery according to another example of the present invention. Fig. 9 is an exploded perspective view of Fig. 8. Fig. 10 is a top view of Fig. 8. Fig. 11 is a side cross-sectional view of Fig. 8. FIG. 12 is a flowchart of a method for manufacturing a secondary battery according to an example of the present invention. FIG. 13 is a flowchart of a method for manufacturing a secondary battery according to another example of the present invention. Specific details for implementing the invention

[0030] Hereinafter, the present invention will be described with reference to the attached drawings.

[0031] FIG. 2 is a partial schematic diagram of a secondary battery according to an example of the present invention, and FIG. 3 is an exploded perspective view of FIG. 2. As shown, the secondary battery (10) according to the present invention includes an electrode assembly (100), an electrode tab stacking portion (200), and an electrode lead (300).

[0032] The electrode assembly (10) may be structured such that an electrode plate (110) consisting of an anode plate and a cathode plate, and a separator of a predetermined shape interposed between the anode plate and the cathode plate are alternately stacked, and depending on the embodiment, it may be applied in various ways such as a wound type, a stack type, or a stack / folding type.

[0033] The electrode tab stacking portion (200) is formed by stacking multiple electrode tabs (210) that extend in one direction from each electrode plate (110) of the electrode assembly (100) and protrude from one side of the electrode assembly (100). In this case, the electrode tab stacking portion (200) corresponds to electrode tabs (210) having the same polarity that protrude from an electrode plate having the same polarity among the positive or negative electrodes.

[0034] In FIGS. 2 and 3, the positive plate and the negative plate are not depicted separately. When the positive plate and the electrode plate are stacked alternately, the positive tab stacking portion protruding from the positive plate is formed by stacking positive tabs extending from one direction of each positive plate, and the negative tab stacking portion protruding from the negative plate is formed by stacking negative tabs extending from the other direction of the negative plate, which is different from the direction of the positive plate. In the following description of the present invention, the positive tab and the negative tab, or the positive plate and the negative plate, will not be distinguished and will be referred to as the electrode tab and the electrode plate, respectively.

[0035] The electrode lead (300) is a plate-shaped plate or metal bar made of a conductive material and is electrically connected to the electrode tabs (210) by contacting at least one of the electrode tabs (210). This electrode lead (300) performs a function corresponding to a predetermined electrode interface that electrically connects the secondary battery and an external application device.

[0036] At this time, as shown in FIGS. 2 and 3, the width of the electrode tabs (210) can be formed wider than the width of the electrode lead (300), and accordingly, some areas of the electrode tabs (210) are coupled with the electrode lead (300), and the remaining areas not coupled with the electrode lead (300) can be further formed on one side or both sides of the electrode lead (300). That is, FIG. 4 is a top view of FIG. 2, and as illustrated, the width (w_200) of the electrode tabs is formed wider than the width (w_300) of the electrode lead, so that the electrode tab stacking portion (200) may be composed of an overlap portion (A) in which the electrode tab stacking portion (200) overlaps with the width of the electrode lead (300) when viewed from above, and a remainder portion (B) located on one or both sides in the width direction of the electrode lead (300) in which the electrode tab stacking portion (200) does not overlap with the width of the electrode lead (300). FIG. 4 illustrates that the remainder portion (B) is formed on both sides of the electrode lead (300), but as in FIG. 5, the remainder portion (B) may be formed only on one side of the electrode lead (300). However, as described below, the remaining portion (B) performs the function of preventing the electrode lead from detaching from the electrode tabs, and it may be more preferable to form it on both sides of the electrode lead in terms of preventing the electrode lead from detaching.

[0037] Here, as shown in FIGS. 2 and 3, the electrode lead (300) can be inserted between electrode tabs (210) in a laminated structure. More specifically, FIG. 6 is a side cross-sectional view of FIG. 2, and the electrode lead (300) can be inserted between the electrode tabs (210) such that some of the electrode tabs (210) are located at the top of the electrode lead (300) and the remaining parts are located at the bottom of the electrode lead (300), and as shown in FIG. 6, the electrode lead (300) can be inserted at approximately the middle of the stacked height of the electrode tabs (210). However, it is not limited thereto, and the electrode tabs (210) can be inserted biased toward the upper or lower side of the stacked height, and considering that the electrode lead (300) and the electrode tabs (210) are joined by welding, it may be preferable to insert it at a height at a certain upper or lower side rather than the middle.

[0038] At this time, in order to facilitate inserting the electrode lead (300) between the electrode tabs (210), one side of the electrode lead (300) that is inserted into the electrode tab (210) may be formed to be pointed. That is, FIG. 7 is a schematic diagram showing a cross-sectional view of an electrode lead and an electrode tab according to an example of the present invention. As shown in the figure, a tapered portion (T) may be formed in the electrode lead (300) such that the thickness decreases from a certain point toward one end, and the tapered portion (T) may be located between the electrode tabs (210). Accordingly, the inconvenience of having to separate the electrode tabs to insert the electrode lead between the electrode tabs can be eliminated, and the electrode lead can be easily inserted between the electrode tabs without separating the electrode tabs.

[0039] Meanwhile, as such, the electrode tabs (210) are formed wider than the electrode leads (300), and with the electrode leads (300) inserted between the stacked electrode tabs (210), the electrode leads (300) are joined to the electrode tabs (210) located in the overlap portion (A), and separately, the electrode tabs (210) located in the remaining portion (B) can be joined to each other. The electrode leads (300), the electrode tabs (210), and the electrode tabs (210) located in the remaining portion (B) can be closely joined to each other using a separate structure such as a clip, and in particular, can be welded to each other through welding.

[0040] In other words, while conventional secondary batteries have a structure in which electrode leads are disposed on the upper or lower part of the electrode tab stacking section and the electrode leads and electrode tabs are welded together, the present invention may have a structure in which lead tabs are inserted and disposed between the stacked electrode tabs and the electrode leads and electrode tabs are welded together. Furthermore, in conventional secondary batteries, the widths of the electrode leads and electrode tabs are formed substantially identically, so there are no electrode tabs formed in the width direction of the electrode leads, whereas in the present invention, the widths of the electrode tabs are formed widely, so that a remaining electrode tab section is formed on one or both sides in the width direction of the electrode leads, thereby allowing the electrode tabs located in the remaining section to be welded together.

[0041] Accordingly, according to the present invention, even if the welded portion between the electrode lead and the electrode tab is weak, the electrode lead can be supported by welding between the remaining electrode tabs formed on both sides of the electrode lead, thereby preventing the electrode lead from completely detaching from the electrode tab even if external impact occurs, and thus the electrical connectivity of the secondary battery can be improved. Furthermore, unlike conventional methods, to weld the electrode lead and the electrode tab together, the electrode lead and the electrode tab are not welded in a straight line at once from the upper or lower surface of the electrode lead, but a first weld is performed at the overlap portion and a second weld is performed at the remaining portion. This prevents the electrode tabs from completely breaking even if over-welding occurs, thereby significantly reducing the defect rate during the production of the secondary battery.

[0042] At this time, more specifically, the electrode tabs (210) located in the electrode lead (300) and the overlap portion (A) can be welded together through ultrasonic welding, and the electrode tabs (210) located in the remaining portion (B) can be welded together through laser welding. This is related to the welding strength and area; since the electrode tabs in the remaining portion are made of the same metal, welding them is relatively easy and can be done with weak welding, whereas the electrode tabs and electrode lead are made of dissimilar metals, making welding them difficult and requiring strong welding. Accordingly, the electrode tabs and electrode lead are joined relatively strongly through ultrasonic welding, which allows for strong welding and welding over a large area, while the electrode tabs themselves can be joined relatively weakly through laser welding, which allows for fine adjustment of welding strength and welding area. In this way, according to the present invention, the type of welding can be selected to suit the precise application between the electrode lead / electrode tabs or between the electrode tabs / electrode tabs.

[0043] Hereinafter, a secondary battery according to another example of the present invention will be described. Content that overlaps with what has been explained above will be omitted.

[0044] FIG. 8 is a partial schematic diagram of a secondary battery according to another example of the present invention, FIG. 9 is an exploded perspective view of FIG. 8, FIG. 10 is a top view of FIG. 8, and FIG. 11 is a side cross-sectional view of FIG. 8. As illustrated, the secondary battery (10) according to the present invention includes an electrode assembly (100), an electrode tab stacking portion (200), and an electrode lead (300), and further includes a coupling member (400).

[0045] In the secondary battery according to the present example, compared to the secondary battery according to the previous example, the electrode lead (300) is not inserted between the stacked electrode tabs (210), but can be placed on the upper or lower part of the electrode tab stacking section (200). FIGS. 8 and 9 show that the electrode lead is placed on the upper part of the upper and lower part of the electrode tab stacking section, and the electrode lead can be electrically connected to the electrode tabs by contacting the upper surface of the electrode tab located at the top of the electrode tab stacking section or by contacting the lower surface of the electrode tab located at the bottom.

[0046] In addition, the secondary battery (10) according to the present example may further include a coupling member (400) provided on the upper part of the electrode lead (300) when the electrode lead (300) is disposed on the upper part of the electrode tab stacking portion (200), or provided on the lower part of the electrode lead (300) when the electrode lead (300) is disposed on the lower part of the electrode tab stacking portion (200).

[0047] Here, the width of the electrode tabs (210) can be formed wider than the width of the electrode lead (300), and the width of the coupling member (400) can also be formed wider than the width of the electrode lead (300), so that a portion of the coupling member (400) is coupled with the electrode lead (300), and the remaining portion is coupled with the electrode tabs (210) of the remaining portion (B).

[0048] That is, in the secondary battery (10) of the present example, the electrode lead (300) is not inserted between the stacked electrode tabs (210) as in the previous example, but rather the electrode lead is placed on the upper or lower part of the electrode tab stacking section (200) as in the conventional method, and a separate coupling member (400) is further provided thereon. By coupling the coupling member (400) to the electrode lead (300) and the electrode tabs (210) of the remaining section (B) respectively, the electrode lead (300) can be firmly supported. Accordingly, not only can the effects such as preventing the electrode lead from detaching and selecting the welding strength, which the present invention intended to solve in the previous example, be maintained, but according to the present example, the process of inserting the electrode lead between the electrode tabs can be omitted, making it possible to manufacture the secondary battery more simply.

[0049] Here, the width of the coupling member (400) is formed to be wider than the width of the electrode lead (300), so that a portion of it can be coupled with the electrode lead (300) and the remaining portion can be coupled with the remaining portion (B) of the electrode tabs (210). Therefore, it may be formed to be wider than the width of the electrode lead (300) but smaller than the width of the upper or lower surface of the electrode tabs (210). However, considering that the coupling member (400) is a support for supporting the electrode lead (300), it may be more preferable to form it to be substantially the same as the width of the upper or lower surface of the electrode tabs (210) in consideration of the coupling force, etc.

[0050] Meanwhile, referring to FIG. 11, the coupling member (400) may be formed by stacking multiple metal foils (410), and the metal foils (410) may be made of the same material as each electrode tab (210). For example, in the case of a positive electrode tab, the coupling member (400) may be formed by stacking multiple aluminum foils, and in the case of a negative electrode tab, the coupling member (400) may be formed by stacking multiple copper foils. The coupling member (400) is formed by stacking at least one metal foil (410), and may be formed by stacking a relatively small number of metal foils (410), such as two or three sheets, or by stacking a relatively large number of metal foils (410), such as dozens of sheets. This can be appropriately selected considering the welding strength, the overall thickness of the secondary battery, etc.

[0051] Furthermore, as described above, the electrode lead (300), the electrode tabs (210) of the overlap portion (A), and the region (A') corresponding to the overlap portion (A) among the coupling member (400) can be welded together through ultrasonic welding, and the electrode tabs (210) of the remaining portion (B) and the region (B') corresponding to the remaining portion among the coupling member (400) can be welded together through laser welding. Here, the region (A') corresponding to the overlap portion among the coupling member refers to the part that overlaps with the electrode lead when the coupling member is viewed from above, and the region (B') corresponding to the remaining portion refers to the part that does not overlap with the electrode lead when the coupling member is viewed from above. This is illustrated in FIG. 10.

[0052] Hereinafter, a method for manufacturing a secondary battery according to another aspect of the present invention will be described.

[0053] FIG. 12 is a flowchart of a method for manufacturing a secondary battery according to an example of the present invention. The method for manufacturing a secondary battery according to the present example may include A1) a step of preparing an electrode assembly; A2) a step of forming an electrode tab stacking portion in which electrode tabs protruding from one side of the electrode assembly are stacked; and A3) a step of arranging an electrode lead to contact at least one of the electrode tabs. At this time, the electrode tab stacking portion may be formed such that the width of the electrode tabs is wider than the width of the electrode lead, as described above.

[0054] A2) In relation to the step of forming the electrode tab stacking portion, when the electrode assembly is prepared, electrode tabs protrude in the same direction from each electrode plate of the electrode assembly, so the electrode tabs protruding from each electrode plate can naturally be in a stacked state. At this time, conventionally, a process of welding the electrode tabs first to bind them together can be performed, but according to the present invention, in this step, the electrode tabs are not welded first, and they can simply be aligned to maintain the state in which the electrode tabs are stacked in a row.

[0055] Subsequently, in step A3), electrode leads can be inserted between the stacked electrode tabs. Accordingly, some of the electrode tabs located in the overlap portion may be located on the upper part of the electrode lead, and the remaining portion may be located on the lower part of the electrode lead.

[0056] After inserting the electrode leads in this manner, the present invention can connect the electrode tabs located in the overlapping portion with the A4) electrode leads and the electrode tabs located in the remaining portion. As previously explained, a separate structure such as a clip can be used to connect the electrode leads and the electrode tabs, or the electrode tabs to each other; in particular, to connect them, the present invention can weld each to each other.

[0057] Here, as described above, electrode tabs located in the electrode lead and the overlap portion can be welded together through ultrasonic welding, and electrode tabs located in the remaining portion can be welded together through laser welding, wherein the electrode lead / electrode tabs can be welded first, and the electrode tabs in the remaining portion can be welded second.

[0058] In a secondary battery manufactured in this manner, electrode tabs are positioned on both the upper and lower parts of the electrode lead, and the electrode tabs are welded together to support the electrode lead. This prevents the electrode lead from completely detaching from the electrode tab when it is separated from the electrode tab due to external impact, thereby stably improving the electrical connectivity of the secondary battery.

[0059] Meanwhile, below, a method for manufacturing a secondary battery according to another example of the present invention described through FIGS. 8 to 11 will be described. The manufacturing method according to this example includes, similar to the method for manufacturing a secondary battery according to one example of the present invention described above, B1) a step of preparing an electrode assembly, B2) a step of forming an electrode tab stacking portion in which electrode tabs protruding from one side of the electrode assembly are stacked, and B3) a step of arranging an electrode lead to contact at least one of the electrode tabs.

[0060] At this time, regarding the step (B2) of forming the electrode tab stacking portion, in the previous example, electrode leads are inserted between the stacked electrode tabs, so the electrode tabs were not welded together first; however, in this example, since the electrode leads are placed on the upper or lower part of the electrode tabs, a process of welding the electrode tabs together can be performed before placing the electrode leads. In this case, since the welding between the electrode tabs corresponds to welding between identical metals, laser welding can be performed. However, even in this example, since the electrode leads and the connecting member can be welded together at once after placing the electrode leads and providing the connecting member thereon, the electrode tabs may not be welded first in step B2).

[0061] In addition, regarding the step (B3) of arranging the electrode leads, in the previous example, the electrode leads were inserted between the electrode tabs, but in this example, the electrode leads can be arranged to contact the upper surface of the electrode tab located at the top of the electrode tab stacking section or the lower surface of the electrode tab located at the bottom.

[0062] After placing the electrode lead on the upper or lower part of the electrode tab stacking portion as described above, according to the present example, B4) the step of further providing a coupling member on the upper or lower part of the electrode lead may be included. That is, if the electrode lead is placed on the upper part of the electrode tab stacking portion, a coupling member may be further provided on the upper part of the electrode lead, and if the electrode lead is placed on the lower part of the electrode tab stacking portion, a coupling member may be further provided on the lower part of the electrode lead.

[0063] Subsequently, according to the present example, B5) a part of the coupling member can be coupled with the electrode lead and the electrode tabs, and the remainder of the coupling member can be coupled with the electrode tabs of the remaining part. More specifically, the region of the coupling member corresponding to the electrode lead, the electrode lead, and the electrode tabs of the overlap portion can be coupled with each other, and the region of the coupling member corresponding to the remaining part and the electrode tabs of the remaining part can be coupled with each other. In this case as described above, the region of the coupling member corresponding to the overlap portion and the electrode lead can be welded together through ultrasonic welding, and the region of the coupling member corresponding to the remaining part and the electrode tabs located in the remaining part can be welded together through laser welding. However, in the case of the present example, as previously discussed, the electrode tabs can be welded to each other before the electrode lead and the coupling member are welded together.

[0064] In a secondary battery manufactured in this manner, a coupling member is additionally positioned at the upper or lower part of the electrode lead, and the coupling member and the electrode tabs are welded together to support the electrode lead. This prevents the electrode lead from completely detaching from the electrode tab when it is separated from the electrode tab due to external impact, thereby stably improving the electrical connectivity of the secondary battery.

[0065] Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will understand that the present invention may be implemented in other specific forms without changing its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. Explanation of the symbols

[0066] 10: Secondary battery 100: Electrode assembly 110: Electrode plate 200: Electrode tab stacking part 210: Each electrode tab 300: Electrode lead 400: Connecting member 410: Each metal foil A: Overlap portion of the electrode tab stacking part B: Remaining part of the electrode tab stacking section A': Area corresponding to the electrode lead among the coupling members B': Area corresponding to the remaining part of the connecting member w_200: Width of electrode tab w_300: Width of electrode lead w_400: Width of the connecting member T: Tapered portion of the electrode lead

Claims

Claim 1 A secondary battery comprising: an electrode assembly; an electrode tab stacking portion in which electrode tabs protruding from one side of the electrode assembly are stacked; and an electrode lead that contacts at least one of the electrode tabs and is electrically connected to the electrode tabs; wherein the electrode tab stacking portion is formed such that the width of the electrode tabs is wider than the width of the electrode lead, and is composed of an overlap portion that overlaps with the width of the electrode lead, and a remainder portion located on one or both sides in the width direction of the electrode lead that does not overlap with the width of the electrode lead, and wherein the electrode lead is inserted in a laminate structure between the electrode tabs such that some of the electrode tabs located in the overlap portion are located on the upper part of the electrode lead and the remaining portions are located on the lower part of the electrode lead, and are coupled to each other with the electrode tabs located in the overlap portion. Claim 2 delete Claim 3 A secondary battery according to claim 1, characterized in that the electrode tabs located in the remaining portion are joined to each other. Claim 4 A secondary battery according to paragraph 3, characterized in that the electrode leads and the electrode tabs located in the overlap portion are welded together through ultrasonic welding, and the electrode tabs located in the remaining portion are welded together through laser welding. Claim 5 A secondary battery according to claim 1, wherein the electrode lead has a tapered portion formed such that its thickness decreases from a certain point toward one end, and the tapered portion is located between the electrode tabs. Claim 6 A secondary battery according to claim 1, wherein the electrode lead contacts the upper surface of an electrode tab located at the top of the electrode tab stacking portion or the lower surface of an electrode tab located at the bottom of the electrode tab stacking portion, and a coupling member is further provided on the upper or lower portion of the electrode lead. Claim 7 A secondary battery according to claim 6, wherein the coupling member is formed such that the width of the coupling member is wider than the width of the electrode lead, so that an area of ​​the coupling member corresponding to the electrode lead is coupled to the electrode lead, and an area of ​​the coupling member corresponding to the remainder is coupled to the electrode tabs of the remainder. Claim 8 A secondary battery according to claim 7, wherein the coupling member is a plurality of metal foils stacked together. Claim 9 A secondary battery according to claim 7, wherein the region corresponding to the electrode lead among the coupling members, the electrode lead, and the electrode tabs of the overlap portion are welded together through ultrasonic welding, and the region corresponding to the remainder among the coupling members, and the electrode tabs located in the remainder are welded together through laser welding. Claim 10 A method for manufacturing a secondary battery comprises: a step of preparing an electrode assembly; a step of forming an electrode tab stacking portion composed of electrode tabs that protrude from one side of the electrode assembly and are stacked; and a step of arranging an electrode lead to contact at least one of the electrode tabs; wherein the electrode tab stacking portion is formed such that the width of the electrode tabs is wider than the width of the electrode lead, and is composed of an overlap portion that overlaps with the width of the electrode lead and a remainder portion that does not overlap with the width of the electrode lead, and wherein, in the step of arranging the electrode lead, the electrode lead is inserted between the electrode tabs in a laminate structure such that some of the electrode tabs located in the overlap portion are located on the upper part of the electrode lead and the remaining portions are located on the lower part of the electrode lead. Claim 11 delete Claim 12 A method for manufacturing a secondary battery, further comprising the step of, in claim 10, joining the electrode leads and the electrode tabs located in the overlap portion together, and joining the electrode tabs located in the remaining portion together. Claim 13 A method for manufacturing a secondary battery according to claim 12, wherein the electrode leads and the electrode tabs located in the overlap portion are welded together through ultrasonic welding, and the electrode tabs located in the remaining portion are welded together through laser welding. Claim 14 A method for manufacturing a secondary battery according to claim 10, further comprising the step of, in the step of arranging the electrode leads, arranging the electrode leads to contact the upper surface of an electrode tab located at the top of the electrode tab stacking portion or the lower surface of an electrode tab located at the bottom of the electrode tab stacking portion, and providing a coupling member on the upper or lower part of the electrode leads. Claim 15 A method for manufacturing a secondary battery according to claim 14, further comprising the step of coupling a region corresponding to the electrode lead among the coupling members, the electrode lead, and the electrode tabs of the overlap portion together, and coupling a region corresponding to the remainder among the coupling members and the electrode tabs of the remainder together. Claim 16 A method for manufacturing a secondary battery according to claim 15, wherein the region corresponding to the electrode lead among the coupling members, the electrode lead, and the electrode tabs of the overlap portion are welded together through ultrasonic welding, and the region corresponding to the remainder among the coupling members and the electrode tabs located in the remainder are welded together through laser welding.

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