Secondary battary and manufacturing method thereof

Abstract

The present disclosure relates to a secondary battery and a method for manufacturing the same, and may include: a case; a plurality of electrode assemblies accommodated inside the case, each comprising a positive tab and a negative tab; a connecting portion in which the plurality of electrode assemblies are electrically connected in series through the case; a positive terminal connected to a positive tab of one of the electrode assemblies; and a negative terminal connected to a negative tab of another of the electrode assemblies.

Description

Technology Field

[0001] The present disclosure relates to a secondary battery and a method for manufacturing the same. Background Technology

[0002] Secondary batteries are used as power sources for portable electronic devices, and several can be connected in series or parallel to be used in hybrid or electric vehicles, etc.

[0003] Generally, an electrode body including a positive electrode, a negative electrode, and a separator is housed in a packaging material, and an electrolyte is injected therein to form a single battery cell.

[0004] When battery cells are connected in series, the voltage can increase, but this may require a large amount of space relative to the required voltage, or the voltage that can be formed may be limited depending on the structural shape. Therefore, research is being conducted on methods to increase the voltage of the battery cells themselves and to ensure the stability of high-voltage battery cells. Prior art literature

[0005] (Patent Document 0001) KR 10-2373537 B1 The problem to be solved

[0006] According to one aspect of the present disclosures, a secondary battery in which electrode assemblies are connected in series in a simple structure and method, and a method for manufacturing the same can be provided.

[0007] According to another aspect of the present disclosure, a secondary battery and a method for manufacturing the same can be provided, which can be widely applied in green technology fields such as electric vehicles, battery charging stations, and other fields utilizing batteries, such as solar power generation and wind power generation. means of solving the problem

[0008] A secondary battery according to one embodiment of the present disclosure may include: a case having an internal receiving space; a plurality of electrode assemblies accommodated within the case, each including a positive electrode tab and a negative electrode tab, with tabs of the same polarity arranged in the same direction; a connecting part providing a serial connection structure in which the plurality of electrode assemblies are electrically connected in series through the case; a positive terminal connected to the positive electrode tab of one of the plurality of electrode assemblies through the serial connection structure and exposed to the outside of the case; and a negative terminal connected to the negative electrode tab of another of the plurality of electrode assemblies through the serial connection structure and exposed to the outside of the case.

[0009] Here, the above case can be provided as a conductive material in the shape of a cuboid.

[0010] In addition, the above connection may be formed by bending so that the positive tab or the negative tab, which is not connected to the positive terminal or the negative terminal, is connected to the inner wall of the case.

[0011] In addition, the above connection can be fixedly joined to the inner wall of the case through laser welding.

[0012] In addition, the above connection may further include an intermediate member provided on the inner wall of the case corresponding to the cathode tab to improve the heterogeneous material welding strength between the cathode tab and the case.

[0013] In addition, the secondary battery may further include an insulating member disposed between the electrode assembly and the connecting part to prevent an internal short circuit.

[0014] In addition, the insulating member may be formed of a non-conductive material.

[0015] In addition, the insulating member may be formed of an elastic body capable of elastic deformation.

[0016] In addition, the insulating member may be provided as a composite material including polycarbonate (PC) and glass fiber (GF).

[0017] In addition, the insulating member is positioned on the opposite side of the case inlet into which the electrode assembly is inserted, and may be installed at a position corresponding to a tab that is not connected to the positive terminal or the negative terminal.

[0018] A method for manufacturing a secondary battery according to another embodiment of the present disclosure may include: an electrode assembly alignment step of aligning a plurality of electrode assemblies, each having a positive tab and a negative tab formed thereon, such that tabs of the same polarity are arranged in the same direction; a case insertion step of inserting the plurality of electrode assemblies into a case; a terminal formation step of forming a positive terminal connected to the positive tab of one of the plurality of electrode assemblies on the outside of the case and forming a negative terminal connected to the negative tab of another of the plurality of electrode assemblies on the outside of the case; and a series connection step of bending the remaining positive tab and negative tab after forming the terminal and connecting them to the inner wall of the case so that the electrode assemblies are connected in series.

[0019] In addition, an insulating member for preventing internal short circuits can be installed between the electrode assembly and the bent positive tab or between the electrode assembly and the bent negative tab.

[0020] In addition, among the insulating members, the insulating member located far from the case insertion port into which the electrode assembly is inserted may be pre-installed at a position corresponding to a tab that is not connected to the positive terminal or the negative terminal inside the case prior to the case insertion step.

[0021] In addition, the above-mentioned bent positive or negative tab can be fixedly joined to the inner wall of the case through laser welding.

[0022] To improve the welding strength of dissimilar materials between the above-mentioned bent cathode tab and the inner wall of the case, an intermediate member may be installed on the inner wall of the case.

[0023] The features and advantages of the present disclosure will become more apparent from the following detailed description based on the accompanying drawings.

[0024] Prior to this, terms and words used in this specification and claims should not be interpreted in their ordinary and dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of this disclosure, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Effects of the invention

[0025] According to one embodiment of the present disclosure, the high voltage characteristics of a secondary battery can be improved by presenting a series connection structure of an electrode assembly by a simple structure and method. Brief explanation of the drawing

[0026] FIG. 1 is a schematic side view illustrating a secondary battery according to one embodiment of the present disclosure. FIG. 2 is an enlarged view of section "A" of FIG. 1. FIG. 3 is an enlarged view of section "B" of FIG. 1. FIG. 4 is a flowchart illustrating a method for manufacturing a secondary battery according to another embodiment of the present disclosure. Figure 5 is a reference diagram showing the process of inserting a plurality of electrode assemblies into a case. FIG. 6 is a reference diagram showing a state in which a terminal is formed on the outside of the case while the electrode assembly is inserted into the case, and the electrode assembly is connected in series with the case. Specific details for implementing the invention

[0027] The terms used to describe an embodiment of the present disclosure are not intended to limit the present disclosure. It should be understood that singular expressions include plural expressions unless otherwise specified in the context.

[0028] In assigning reference numerals to the components of the drawings, identical components are assigned the same reference numeral whenever possible, even if they are shown in different drawings, and similar components are assigned similar reference numerals.

[0029] Drawings may be schematic or exaggerated for the purpose of illustrating embodiments. In this document, expressions such as “have,” “may have,” “include,” or “may include” indicate the presence of such features (e.g., numerical values, functions, operations, or components such as parts) and do not exclude the presence of additional features.

[0030] Terms such as "one," "other," "another," "first," and "second" are used to distinguish one component from another, and the components are not limited by these terms.

[0031] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the attached drawings.

[0032] FIG. 1 is a schematic side view illustrating a secondary battery according to one embodiment of the present disclosure, FIG. 2 is an enlarged view illustrating part "A" of FIG. 1, FIG. 3 is an enlarged view illustrating part "B" of FIG. 1, FIG. 4 is a flowchart illustrating a method for manufacturing a secondary battery according to another embodiment of the present disclosure, FIG. 5 is a reference diagram showing a process of inserting a plurality of electrode assemblies into a case, and FIG. 6 is a reference diagram showing a state in which a terminal is formed on the outside of the case while the electrode assemblies are inserted into the case, and the electrode assemblies are connected in series with the case.

[0033] A secondary battery according to one embodiment of the present disclosure may include: a case (100) having an internal receiving space; a plurality of electrode assemblies (200) each receiving a plurality of electrode assemblies (200) and each including a positive electrode tab (210) and a negative electrode tab (220), with tabs of the same polarity arranged in the same direction; a connecting part (300) providing a serial connection structure in which the plurality of electrode assemblies (200) are electrically connected in series through the case (100); a positive terminal (400) connected to the positive electrode tab (210) of one of the electrode assemblies (200) through the serial connection structure and exposed to the outside of the case (100); and a negative terminal (500) connected to the negative electrode tab (220) of another electrode assembly among the plurality of electrode assemblies (200) through the serial connection structure and exposed to the outside of the case (100).

[0034] As illustrated in FIG. 1, a receiving space may be formed inside the case (100) to accommodate a plurality of electrode assemblies (200). The size of the receiving space of the case (100) may be determined by considering the size and number of electrode assemblies (200) accommodated inside.

[0035] Here, the case (100) may be provided as a cuboid-shaped conductive material.

[0036] The case (100) may be formed as a rectangular prism or a cube with a square cross-section, and may be provided with a hollow structure to form an internal receiving space. Additionally, the case (100) may be provided with an electrically conductive material to be electrically connected in series with a plurality of electrode assemblies (200).

[0037] In the secondary battery according to the present disclosure, a single case (100) may be applied, and if provided as necessary, two or more cases (100) may be connected to each other to maintain a short-circuit state.

[0038] The electrode assembly (200) can be accommodated inside the case (100), and a plurality of them may be provided to have a mutually serial connection structure inside the case (100) and inserted inside the case (100). Each of the plurality of electrode assemblies (200) may include a positive electrode tab (210) and a negative electrode tab (220).

[0039] As shown in FIG. 1, at both ends of each electrode assembly (200), a positive electrode tab (210) and a negative electrode tab (220) protruding outside the electrode assembly (200) may be provided.

[0040] Here, a plurality of electrode assemblies (200) may be arranged such that tabs of the same polarity are located in the same direction. That is, in the plurality of electrode assemblies (200), positive tabs (210) may be positioned in one direction of the electrode assembly (200) and negative tabs (220) may be positioned in the other direction.

[0041] The connecting portion (300) can provide a series connection structure that allows a plurality of electrode assemblies (200) to be electrically connected in series through a case (100) made of a conductive material.

[0042] Here, the connection portion (300) may be formed by bending so that the positive tab (210) or the negative tab (220), which is not connected to the positive terminal (400) or the negative terminal (500), is connected to the inner wall of the case (100).

[0043] Specifically, the connecting portion (300) can be defined as the positive tab (210) or negative tab (220) formed at both ends of the electrode assembly (200) that is not connected to the positive terminal (400) or negative terminal (500), and is formed to be bent through bending processing so as to be connected to the inner wall of the case (100).

[0044] In other words, the positive tab (210) or negative tab (220) provided at both ends of the electrode assembly (200) remains the positive tab (210) or negative tab (220) before bending, but if it is bent through bending, it can be interpreted as meaning the connecting part (300).

[0045] Meanwhile, the positive terminal (400) may be formed to be electrically connected to the positive tab (210) of one of the electrode assemblies (200) and exposed to the outside of the case (100).

[0046] Additionally, the negative terminal (500) may be formed to be electrically connected to the negative tab (220) of another electrode assembly (200) among the plurality of electrode assemblies (200) and exposed to the outside of the case (100).

[0047] For example, in the present disclosure, as shown in FIG. 1, when two electrode assemblies (200) are provided, the positive tab (210) of one of the two electrode assemblies (200) may be electrically connected to a positive terminal (400) and the negative tab (220) of the other electrode assembly (200) may be electrically connected to a negative terminal (500).

[0048] A positive terminal (400) may be formed on one side of the case (100), and a negative terminal (500) may be formed on the other side of the case (100). Here, the positive terminal (400) and the negative terminal (500) may be formed to be insulated from the case (100) by means of insulators (410, 510), respectively.

[0049] Here, the connecting part (300) can be fixedly connected to the inner wall of the case (100) through laser welding.

[0050] The bent positive tab (210) and negative tab (220) can be a connecting part (300), which can be electrically connected to the inner wall of the case (100) through laser welding.

[0051] The remaining positive tabs (210) and negative tabs (220) that are not connected to the positive terminal (400) or negative terminal (500) in the plurality of electrode assemblies (200) can become a connecting part (300) through bending processing, and as the connecting part (300) is electrically connected to a case (100) which is a conductive material through laser welding, the plurality of electrode assemblies (200) can be connected in a serial connection structure through the case (100).

[0052] The above connection portion (300) may further include an intermediate member (310) provided on the inner wall of the case (100) corresponding to the cathode tab (220) to improve the heterogeneous material welding strength between the cathode tab (220) and the case (100).

[0053] As shown in FIG. 2, an intermediate member (310) may be provided to facilitate welding and to improve welding quality and strength after welding when welding a cathode tab (220) and a case (100) of different materials.

[0054] For reference, the cathode tab (220) is typically made of copper (Cu) and the case (100) can be made of aluminum (Al). Since such dissimilar materials are difficult to weld and it is difficult to maintain a constant welding strength even after welding, a separate intermediate member (310) can be used to weld the dissimilar materials.

[0055] For example, copper and aluminum are metals with different physical and chemical properties, and when directly welding dissimilar materials, thermal conductivity, melting point, and coefficient of thermal expansion differ, which can cause thermal stress or non-uniform cooling and form brittle compounds at the joint.

[0056] Therefore, using the intermediate member (310) provides chemical compatibility to the dissimilar materials. Since the intermediate member (310) has suitable compatibility between the dissimilar materials, it can help suppress reactions between the dissimilar materials and enable stable bonding. In addition, the intermediate member (310) can mitigate the difference in thermal expansion coefficients between the dissimilar materials to prevent deformation or cracking caused by thermal stress and increase the strength of the bonding surface, thereby improving mechanical performance.

[0057] The intermediate member (310) may be provided on the inner wall of the case (100) corresponding to the negative electrode tab (220) that has been bent as shown in FIG. 2, among the connecting parts (300). This intermediate member (310) may be provided in a state of being pre-installed on the corresponding part of the inner wall of the case (100) for ease of welding. Here, the material of the intermediate member (310) may be selectively determined by considering the material of different materials, but if the negative electrode tab (220) is copper and the case (100) is made of aluminum, the intermediate member (310) may be provided with a material including at least one of zinc, silver, and nickel.

[0058] For reference, as shown in FIG. 3, the connecting part (300) formed by the bending process anode tab (210) may not be provided with an intermediate member (310). Since the anode tab (210) is made of aluminum of the same material as the case (100), it can be welded in the usual way without using an intermediate member (310).

[0059] Meanwhile, the secondary battery according to the present disclosure may further include an insulating member (600) disposed between the electrode assembly (200) and the connecting part (300) to prevent an internal short circuit.

[0060] As illustrated in FIGS. 2 and 3, an insulating member (600) may be placed between the electrode assembly (200) and the connecting member (300). As shown in FIG. 2, the insulating member (600) may be provided between the connecting member (300) and the electrode assembly (200) by a bent negative tab (220), and as shown in FIG. 3, it may also be placed between the connecting member (300) and the electrode assembly (200) by a bent positive tab (210) to prevent an internal short circuit from occurring due to the electrode assembly (200) swelling or being damaged.

[0061] Accordingly, the insulating member (600) can be formed of a non-conductive material.

[0062] Since the insulating member (600) is provided as a non-conductive material, it can be placed between the electrode assembly (200) and the connecting part (300) to prevent the electrode assembly (200) from coming into direct contact with the connecting part (300) even if the electrode assembly (200) swells or is damaged.

[0063] Here, the insulating member (600) may be formed of an elastic body capable of elastic deformation.

[0064] As the insulating member (600) is provided as an elastic body, it can prevent the electrode assembly (200) from coming into direct contact with the connecting part (300) between the electrode assembly (200) and the connecting part (300) by elastically deforming when the electrode assembly (200) swells or is damaged. Additionally, the insulating member (600) can be provided as a material with excellent chemical resistance to maintain durability against chemical substances such as electrolytes, and can be provided as a high-strength material.

[0065] Accordingly, the insulating member (600) may be provided as a composite material including polycarbonate and glass fiber.

[0066] As the insulating member (600) is provided as a composite material including polycarbonate and glass fiber, the insulating member (600) is a non-conductive material that is elastically deformable and has chemical resistance while securing strength and rigidity.

[0067] Here, glass fibers may be included in a ratio of 10 to 30 percent relative to the total composition. If the glass fibers have a ratio of 10 to 30 percent, the insulating member (600) has excellent processability and surface quality, but if it falls outside this range, processability and surface quality may be limited.

[0068] Here, the insulating member (600) may be pre-installed on the inner wall opposite to the case insertion port (110) into which the electrode assembly (200) is inserted.

[0069] Referring to FIG. 1, a plurality of insulating members (600) may be provided inside the case (100). Although the insulating members (600) may be installed so as to be positioned between the electrode assembly (200) and the connecting part (300) after inserting a plurality of electrode assemblies (200) into the case (100), the insulating members (600) of a specific part may be installed in advance inside the case (100) to improve installation convenience and reduce manufacturing time.

[0070] An insulating member (600) that can be pre-installed inside the case (100) may be located on the inner wall of the case (100) that is far from the case inlet (110) where the electrode assembly (200) is inserted. At this time, it may be pre-installed at a position corresponding to a tab (bent positive tab (210) or negative tab (220)) that is not connected to the positive terminal (400) or negative terminal (500).

[0071] Hereinafter, a method for manufacturing a secondary battery according to another embodiment of the present disclosure will be described with reference to FIGS. 4 to 6.

[0072] As illustrated in FIG. 4, a method for manufacturing a secondary battery according to another embodiment of the present disclosure comprises: an electrode assembly alignment step (S10) of aligning a plurality of electrode assemblies (200) having positive tabs (210) and negative tabs (220) formed thereon so that tabs of the same polarity are arranged in the same direction; a case insertion step (S20) of inserting the plurality of electrode assemblies (200) into a case (100); and a terminal formation step (S30) of forming a positive terminal (400) connected to the positive tab (210) of one of the plurality of electrode assemblies (200) on the outside of the case (100) and forming a negative terminal (500) connected to the negative tab (220) of another of the plurality of electrode assemblies (200) on the outside of the case (100). and may include a serial connection step (S40) in which the remaining positive electrode tab (210) and the negative electrode tab (220) formed after the terminal are bent and connected to the inner wall of the case (100) so that the electrode assemblies (200) are connected in series.

[0073] The electrode assembly alignment step (S10) may refer to a process of aligning a plurality of electrode assemblies (200), in which positive electrode tabs (210) and negative electrode tabs (220) are formed at both ends, such that tabs of the same polarity are arranged in the same direction.

[0074] As illustrated in FIG. 5, according to the electrode assembly alignment step (S10), a plurality of electrode assemblies (200) may have tabs of the same polarity (i.e., positive tab (210) or negative tab (220)) arranged in the same direction.

[0075] Accordingly, as shown in FIG. 5, for example, if the positive electrode tab (210) is placed on the left side of the electrode assembly (200), the negative electrode tab (220) can be arranged to be placed on the right side. At this time, the positive electrode tab (210) or the negative electrode tab (220) can be formed in a straight line extending parallel to the electrode assembly (200).

[0076] The case insertion step (S20) may mean the process of inserting a plurality of electrode assemblies (200) aligned as above into the case (100).

[0077] At this time, a plurality of electrode assemblies (200) can be inserted into the interior of the case (100) through a case insertion port (110) formed on one side of the case (100). At this time, an insulating member (600) and an intermediate member (310) may be pre-installed inside the case (100), which will be explained again later.

[0078] As illustrated in FIG. 6, the terminal forming step (S30) may mean the process of forming a positive terminal (400) on one side of the outside of the case (100) that is connected to the positive tab (210) of one electrode assembly (200) among the electrode assemblies (200) inserted into the case (100).

[0079] Additionally, the terminal forming step (S30) may also include the process of forming a negative terminal (500) on the other side of the case (100) that is connected to the negative tab (220) of another electrode assembly (200) among the electrode assemblies (200) inserted into the case (100).

[0080] The positive terminal (400) and the negative terminal (500) can be formed to be exposed to the outside of the case (100) and can be formed to be insulated from the case (100) by an insulator (410, 510).

[0081] The serial connection step (S40) may refer to a process of forming a connection part (300) by bending the remaining positive tab (210) and negative tab (220) that are connected to the positive terminal (400) and negative terminal (500), respectively.

[0082] Additionally, the serial connection step (S40) may include a process of electrically connecting a plurality of electrode assemblies (200) inside the case (100) through laser welding so that the bending processed positive electrode tab (210) and negative electrode tab (220), i.e., the connecting part (300), are electrically connected to the inner wall of the case (100) made of a conductive material.

[0083] Here, an insulating member (600) for preventing internal short circuits can be installed between the electrode assembly (200) and the bent positive tab (210), and between the electrode assembly (200) and the bent negative tab (220), respectively.

[0084] Although multiple insulating members (600) may be installed even after the electrode assembly (200) is inserted into the case (100), it is also possible to install insulating members (600) at specific locations that do not interfere or obstruct the process of inserting the electrode assembly (200) into the case (100) in advance to improve installation convenience and shorten manufacturing time.

[0085] Accordingly, among the insulating members (600), the insulating member (600) located far from the case insertion port (110) into which the electrode assembly (200) is inserted may be pre-installed at a position corresponding to a tab that is not connected to the positive terminal (400) or the negative terminal (500) inside the case (100) prior to the case insertion step (S20).

[0086] Referring to FIG. 5, among the plurality of insulating members (600), the insulating member (600) located far from the case inlet (110), that is, on the opposite side of the case inlet (110), can be pre-installed on the inner wall of the case (100), and can be installed at a position corresponding to a bending processed positive tab (210) or negative tab (220), which is defined as a tab that is not connected to the positive terminal (400) or negative terminal (500), i.e., a connecting part (300).

[0087] The insulating member (600) has been described in detail in one embodiment of the present disclosure described above, so it is omitted here.

[0088] Meanwhile, the above-mentioned bending process positive electrode tab (210) or negative electrode tab (220) can be fixedly connected to the inner wall of the case (100) through laser welding.

[0089] The electrode assembly (200) inserted inside the case (100) has the remaining positive tab (210) and negative tab (220) that are not connected to the positive terminal (400) or negative terminal (500) in the serial connection step (S40) bent toward the inner wall of the case (100) through bending processing, and the positive tab (210) or negative tab (220) thus bent can be fixedly joined to the case (100) through laser welding.

[0090] Here, an intermediate member (310) can be installed on the inner wall of the case (100) to improve the welding strength of different materials between the bent cathode tab (220) and the inner wall of the case (100).

[0091] The intermediate member (310) can be installed at a specific point on the inner wall of the case (100) corresponding to the bent cathode tab (220), and as shown in FIG. 5, when a specific insulating member (600) is installed inside the case (100) in advance, the intermediate member (310) can also be installed in advance at a corresponding point.

[0092] The present disclosure has been described in detail above through specific embodiments. The embodiments are intended to specifically explain the present disclosure, and the present disclosure is merely illustrative of the invention and is not intended to limit the appended claims. It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope and spirit of the invention, and that such variations and modifications fall within the scope of the appended claims. Explanation of the symbols

[0093] 100: Case 110: Case input slot 200: Electrode assembly 210: Positive tab 220: Negative tab 300: Connection part 310: Intermediate absence 400: Positive terminal 500: Negative terminal 600: Insulating member

Claims

Claim 1 A secondary battery comprising: a case having an internal receiving space; a plurality of electrode assemblies accommodated within the case, each including a positive tab and a negative tab, with tabs of the same polarity arranged in the same direction; a connecting part providing a serial connection structure in which the plurality of electrode assemblies are electrically connected in series through the case; a positive terminal connected to the positive tab of one of the plurality of electrode assemblies through the serial connection structure and exposed to the outside of the case; and a negative terminal connected to the negative tab of another of the plurality of electrode assemblies through the serial connection structure and exposed to the outside of the case. Claim 2 A secondary battery according to claim 1, wherein the case is provided as a cuboid-shaped conductive material. Claim 3 A secondary battery according to claim 1, wherein the connecting portion is formed by bending so that the positive tab or the negative tab not connected to the positive terminal or the negative terminal is connected to the inner wall of the case. Claim 4 A secondary battery according to claim 3, wherein the connecting portion is fixedly coupled to the inner wall of the case through laser welding. Claim 5 A secondary battery according to claim 3, wherein the connecting portion further comprises an intermediate member provided on the inner wall of the case corresponding to the cathode tab to improve the heterogeneous material welding strength between the cathode tab and the case. Claim 6 The secondary battery according to claim 1, wherein the secondary battery further comprises an insulating member disposed between the electrode assembly and the connecting portion to prevent an internal short circuit. Claim 7 In claim 6, the insulating member is formed of a non-conductive material, a secondary battery. Claim 8 A secondary battery according to claim 7, wherein the insulating member is formed of an elastic body capable of elastic deformation. Claim 9 A secondary battery according to claim 8, wherein the insulating member is provided as a composite material comprising polycarbonate and glass fiber. Claim 10 A secondary battery according to claim 6, wherein the insulating member is pre-installed on the inner wall opposite the case opening into which the electrode assembly is inserted. Claim 11 A method for manufacturing a secondary battery comprising: an electrode assembly alignment step of aligning a plurality of electrode assemblies, each having a positive tab and a negative tab formed thereon, such that tabs of the same polarity are arranged in the same direction; a case insertion step of inserting the plurality of electrode assemblies into a case; a terminal formation step of forming a positive terminal connected to the positive tab of one of the plurality of electrode assemblies on the outside of the case and forming a negative terminal connected to the negative tab of another of the plurality of electrode assemblies on the outside of the case; and a series connection step of bending the remaining positive tab and the negative tab after forming the terminals, and connecting them to the inner wall of the case to configure the electrode assemblies to be connected in series. Claim 12 A method for manufacturing a secondary battery according to claim 11, wherein an insulating member for preventing an internal short circuit is installed between the electrode assembly and the bent positive tab or between the electrode assembly and the bent negative tab. Claim 13 A method for manufacturing a secondary battery according to claim 12, wherein an insulating member located far from the case insertion port into which the electrode assembly is inserted among the insulating members is pre-installed at a position corresponding to a tab that is not connected to the positive terminal or the negative terminal inside the case prior to the case insertion step. Claim 14 A method for manufacturing a secondary battery according to claim 11, wherein the bending processed positive electrode tab or negative electrode tab is fixedly joined to the inner wall of the case through laser welding. Claim 15 A method for manufacturing a secondary battery according to claim 13, wherein an intermediate member is installed on the inner wall of the case to improve the heterogeneous material welding strength between the bent negative tab and the inner wall of the case.

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