Secondary battery and manufacturing method therefor

Abstract

A secondary battery according to one aspect of the present invention comprises an electrode assembly, an electrode lead, and a fixing unit. The electrode assembly may include an electrode part, and an electrode tab part that is formed on one end of the electrode part and is bent in one direction. The electrode lead may include a connection part and a lead-out part that is bent with respect to the connection part and extends, and the connection part may be welded to the electrode tab part. The fixing unit may be disposed on one end of the electrode assembly. The fixing unit may include an upper bracket having a first compression surface and a first opposing surface, a lower bracket having a second compression surface and a second opposing surface, a connecting portion connecting the upper bracket and the lower bracket, and a slit.

Description

Secondary battery and method of manufacturing the same

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0031258 dated March 11, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0002] The present invention relates to a secondary battery and a method for manufacturing the same.

[0003] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased rapidly, and the development of electric vehicles, energy storage batteries, robots, and satellites has accelerated, research on high-performance secondary batteries capable of repeated charging and discharging is actively underway.

[0004] Currently commercialized rechargeable batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium-ion batteries. Among these, lithium-ion batteries are gaining attention for their advantages, such as the ability to freely charge and discharge with almost no memory effect compared to nickel-based batteries, a very low self-discharge rate, and high energy density.

[0005] These lithium secondary batteries primarily use lithium-based oxides and carbon materials as the positive and negative active materials, respectively. Additionally, the lithium secondary battery comprises a positive member and a negative member coated with these positive and negative active materials, respectively; an electrode assembly in which the positive and negative members are arranged with a separator in between; and an outer casing that seals and encloses the electrode assembly together with an electrolyte.

[0006] Meanwhile, lithium secondary batteries can be classified according to the shape of the battery case into can-type secondary batteries, in which the electrode assembly is embedded in a metal can, and pouch-type secondary batteries, in which the electrode assembly is embedded in a pouch of aluminum laminate sheets. Furthermore, can-type secondary batteries can be further classified into cylindrical batteries and prismatic batteries depending on the shape of the metal can.

[0007] In the case of pouch-type secondary batteries, multiple thin-film tabs connected to electrode plates are welded to electrode leads, and the electrode assembly is housed within the pouch. At this stage, space must be secured for the welding of the tabs and electrode leads, which presents a problem in that it is difficult to increase the energy density per unit volume of the battery.

[0008] To solve the above problem, the objective of the present invention is to provide a secondary battery and a method for manufacturing the same that can increase energy density per unit volume by reducing the space occupied by thin film tabs, etc., inside the battery case.

[0009] To solve the above problem, the objective of the present invention is to provide a secondary battery and a method for manufacturing the same, wherein the electrode tab and the electrode lead can be easily welded.

[0010] A secondary battery according to one embodiment of the present invention comprises an electrode assembly, an electrode lead, and a fixing unit. The electrode assembly may have an electrode portion and an electrode tab portion formed at one end of the electrode portion and bent in one direction. The electrode lead may have a connecting portion and an extension portion that is bent and extended relative to the connecting portion, and the connecting portion may be welded to the electrode tab portion. A fixing unit may be disposed at one end of the electrode assembly. The fixing unit may have an upper bracket having a first pressure surface and a first opposing surface, a lower bracket having a second pressure surface and a second opposing surface, a pair of joints connecting the upper bracket and the lower bracket, and a slit defined by the upper bracket, the lower bracket, and the pair of joints.

[0011] In a secondary battery according to one embodiment of the present invention, an upper bracket, a lower bracket, and a pair of joints can be integrally molded.

[0012] A secondary battery according to one embodiment of the present invention may further include an insulating portion surrounding a part of the lead portion.

[0013] A secondary battery according to one embodiment of the present invention may further include a battery case having a first case and a second case. The first case may have a first electrode assembly receiving portion and a first bump region formed at least one end of the first electrode assembly receiving portion. The second case may have a second electrode assembly receiving portion and a second bump region formed at least one end of the second electrode assembly receiving portion. An electrode assembly may be received in the first electrode assembly receiving portion and the second electrode assembly receiving portion.

[0014] In a secondary battery according to one embodiment of the present invention, the lead portion may be extended outside the battery case.

[0015] In a secondary battery according to one embodiment of the present invention, the electrode tab portion may be pre-welded.

[0016] In a secondary battery according to one embodiment of the present invention, the first opposing surface of the upper bracket may face one side of the lead portion, and the second opposing surface of the lower bracket may face the other side of the lead portion.

[0017] In a secondary battery according to one embodiment of the present invention, a first pressure surface of the upper bracket may be in contact with the electrode tab portion, and a second pressure surface of the lower bracket may be in contact with the connection portion.

[0018] In a secondary battery according to one embodiment of the present invention, the length of the first opposing surface may be the same as the width (Wc) of the lead portion.

[0019] In a secondary battery according to one embodiment of the present invention, the distance (d) between the first opposing surface and the second opposing surface may be greater than the thickness of the lead portion.

[0020] In a secondary battery according to one embodiment of the present invention, the length of the slit (Ls) may be greater than the width (Wi) of the insulating portion.

[0021] In a secondary battery according to one embodiment of the present invention, inclined surfaces may be formed at both ends of the upper bracket and the lower bracket.

[0022] In a secondary battery according to one embodiment of the present invention, the width of the electrode tab portion may be 40 to 70% of the width of the electrode assembly.

[0023] In a secondary battery according to one embodiment of the present invention, the lead portion may be perpendicular to one end surface of the electrode assembly.

[0024] In a secondary battery according to one embodiment of the present invention, the inner walls of the first bump region and the second bump region may be made of the same material as the battery case.

[0025] In a secondary battery according to one embodiment of the present invention, the inner walls of the first bump region and the second bump region may be made of a material different from that of the battery case.

[0026] In a secondary battery according to one embodiment of the present invention, the first bump region and the second bump region may be symmetrical with respect to the center of the thickness direction of the electrode assembly.

[0027] In a secondary battery according to one embodiment of the present invention, the first bump region and the second bump region may be located at the center of the battery case along the width direction of the electrode assembly.

[0028] In a secondary battery according to one embodiment of the present invention, the shape of the inner wall surface of the first bump region and the second bump region can be matched with the outer surface of the upper bracket and the lower bracket, respectively.

[0029] In a secondary battery according to one embodiment of the present invention, the battery case may be a pouch.

[0030] A method for manufacturing a secondary battery according to one embodiment of the present invention includes a preparation step of preparing an electrode assembly having an electrode portion and an electrode tab portion; a joining step of joining the electrode tab portion and the electrode lead having a connecting portion and an outgoing portion extending vertically from the connecting portion; a rotation step of rotating the electrode lead joined to the electrode tab portion by 90°; and a fixing unit joining step of placing the fixing unit at one end of the electrode assembly by passing the outgoing portion through a slit of the fixing unit.

[0031] A secondary battery manufacturing method according to one embodiment of the present invention may further include an insulating portion placement step in which the insulating portion is arranged to surround a portion of the lead portion.

[0032] A method for manufacturing a secondary battery according to one embodiment of the present invention may further include a packaging step of accommodating an electrode assembly within a battery case.

[0033] As described above, according to one aspect of the present invention, the energy density per unit volume can be increased by reducing the space occupied by thin film tabs, etc., inside the battery case.

[0034] In addition, according to one aspect of the present invention, the electrode tab and the electrode lead can be easily welded.

[0035] FIG. 1 is a drawing showing a secondary battery in which electrode tab portions are formed in both directions according to an embodiment of the present invention.

[0036] FIGS. 2A and FIGS. 2B are drawings showing an anode member and a cathode member according to an embodiment of the present invention.

[0037] FIG. 3 is a drawing showing that an electrode tab portion is formed in a secondary battery according to one embodiment of the present invention.

[0038] FIG. 4 is a drawing showing an electrode lead according to one embodiment of the present invention.

[0039] FIG. 5 is a diagram showing the state in which the electrode tab portion and the electrode lead of a secondary battery are joined according to one embodiment of the present invention.

[0040] FIG. 6 is a drawing showing the state in which the electrode tab portion of a secondary battery according to one embodiment of the present invention is bent after being joined with the electrode lead.

[0041] FIG. 7 is a drawing showing a fixed unit of a secondary battery according to one embodiment of the present invention.

[0042] FIG. 8 is a drawing showing a cross-section of a fixed unit of a secondary battery according to one embodiment of the present invention.

[0043] FIG. 9 is a diagram showing the process of a lead portion of an electrode lead penetrating a slit of a fixed unit in a secondary battery according to one embodiment of the present invention.

[0044] FIG. 10 is a side cross-sectional view of an electrode tab portion and an electrode lead of a secondary battery according to one embodiment of the present invention in a state where they are fixed by a fixing unit.

[0045] FIG. 11 is a drawing showing a fixed unit of a secondary battery according to one embodiment of the present invention.

[0046] FIG. 12 is a drawing showing an electrode assembly in a secondary battery according to one embodiment of the present invention, which is cased by a battery case.

[0047] FIGS. 13a and FIGS. 13b are cross-sectional views of an electrode assembly in a secondary battery according to one embodiment of the present invention, in a state where the electrode assembly is cased by a battery case.

[0048] FIG. 14 is a flowchart illustrating a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0049] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0050] The terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this invention, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0051] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that in the accompanying drawings, identical components are indicated by the same reference numerals whenever possible. Furthermore, detailed descriptions of known functions and configurations that may obscure the essence of the present invention will be omitted. For the same reason, some components in the accompanying drawings may be exaggerated, omitted, or schematically depicted.

[0052] Hereinafter, a secondary battery according to one embodiment of the present invention will be described.

[0053] FIG. 1 is a drawing showing a secondary battery in which an electrode tab portion is formed in both directions according to an embodiment of the present invention, FIG. 2a and FIG. 2b are drawings showing a positive electrode member and a negative electrode member according to an embodiment of the present invention, FIG. 3 is a drawing showing that an electrode tab portion is formed in a secondary battery according to an embodiment of the present invention, FIG. 4 is a drawing showing an electrode lead according to an embodiment of the present invention, FIG. 5 is a drawing showing the state in which the electrode tab portion and the electrode lead of a secondary battery according to an embodiment of the present invention are joined, and FIG. 6 is a drawing showing the state in which the electrode tab portion of a secondary battery according to an embodiment of the present invention is bent after being joined with the electrode lead.

[0054] As illustrated in FIG. 1, a secondary battery (1000) according to an embodiment of the present invention includes an electrode assembly (1100), an electrode lead (1200), an insulating part (1300), a fixing part (1400), and a battery case (1500).

[0055] The electrode assembly (1100) comprises an electrode portion (1110) and an electrode tab portion (1120). The electrode portion (1110) comprises a plurality of unit electrode members (1111, 1112) and a separator (1113). An active material may be coated on the unit electrode members (1111, 1112). The plurality of unit electrode members (1111, 1112) may comprise an anode member (1111) on which an active material, such as a transition metal oxide, is coated on a metal plate such as aluminum, and a cathode member (1112) on which an active material, such as graphite or carbon, is coated on a metal plate such as copper or nickel. The separator (1113) is positioned between the plurality of unit electrode members (1111, 1112) to prevent short circuits between the unit electrode members (1111, 1112). The material of the separator (1113) may be polyethylene, polypropylene, or a composite thereof.

[0056] The electrode portion (1110) of the electrode assembly (1100) can be formed by placing a separator (1113) between an anode member (1111) and a cathode member (1112) that are alternately arranged. That is, in one embodiment, the electrode portion (1110) is formed by alternately stacking the anode member (1111), the separator (1113), the cathode member (1112), and the separator (1113) in that order. Accordingly, the electrode assembly (1100) can have a rectangular shape with a height (H) and a width (W). In another embodiment, the electrode portion (1110) can be formed by arranging the anode member (1111), the separator (1113), and the cathode member (1112) in that order and then winding it up.

[0057] As illustrated in FIGS. 2a and 2b, a blank tab (1121, 1122) on which no active material is applied is formed on a plurality of unit electrode members (1111, 1112). In this embodiment, a blank tab (1121) may be formed on one end of the positive electrode member (1111), and a blank tab (1122) may be formed on the other end of the negative electrode member (1112) opposite to the one end, but is not limited thereto. Meanwhile, in one embodiment, the unit electrode members (1111, 1112) and the blank tab (1121, 1122) may be formed integrally by cutting a predetermined portion of a metal plate using a laser or the like to leave the unit electrode members (1111, 1112) and the blank tab (1121, 1122).

[0058] The non-removable tabs (1121) of the positive electrode member (1111) overlap each other at a first position, and the non-removable tabs (1122) of the negative electrode member (1112) overlap each other at a second position. In another embodiment, there may be two or more positions where the non-removable tabs (1121, 1122) overlap in each of the positive electrode member (1111) and the negative electrode member (1112).

[0059] The electrode tab portion (1120; 1121A, 1122A) can be formed by connecting multiple non-reinforced tabs (1121, 1122) that overlap at the same location to each other using ultrasonic welding, laser welding, etc. (Fig. 3). By forming the electrode tab portion (1120; 1121A, 1122A), the movement of current generated in the electrode portion (1110) becomes easier.

[0060] The width of the electrode tab portion (1120; 1121A, 1122A) may be 40 to 70% of the width of the electrode assembly (1100). The present invention can increase the bonding stability with the electrode lead (1200) by forming the width of the electrode tab portion (1120) wide.

[0061] The electrode tab portion (1121A) formed by connecting the non-existent tab (1121) of the positive electrode member (1111) becomes the positive electrode tab, and the electrode tab portion (1122A) formed by connecting the non-existent tab (1122) of the negative electrode member (1112) becomes the negative electrode tab. In this embodiment, the positive electrode tab is formed in a direction perpendicular to one surface of the electrode assembly (1100), and the negative electrode tab is formed in a direction perpendicular to the other surface of the electrode assembly (1100). In this embodiment, the positive electrode tab (1121A) and the negative electrode tab (1122A) are described as protruding in different directions, but are not necessarily limited thereto, and the positive electrode tab (1121A) and the negative electrode tab (1122A) may protrude in the same direction from one end of the electrode assembly.

[0062] An electrode lead (1200) that supplies electricity to the outside of the secondary battery (1000) is connected to the electrode tab portion (1120; 1121A, 1122A) of the electrode assembly (1100) by spot welding or the like. Specifically, the positive lead is connected to the positive electrode tab portion (1121A) and extends outward, and the negative lead is connected to the negative electrode tab portion (1122A) and extends outward.

[0063] The electrode lead (1200) is joined to the electrode tab portion (1120). As illustrated in FIG. 4, the electrode lead (1200) has a connecting portion (1210) and an extraction portion (1220). The connecting portion (1210) is joined to the electrode tab portion (1120), and the extraction portion (1220) extends outside the battery case (1500). The connecting portion (1210) and the extraction portion (1220) have the same width (Wc). Preferably, the length in the width (Wc) direction of the connecting portion (1210) and the length in the width (Wt) direction of the electrode tab portion (1120) are also the same. The extraction portion (1220) is bent at a predetermined angle relative to the connecting portion (1210). In this embodiment, the angle at which the extraction portion (1220) is bent relative to the connecting portion (1210) is approximately 90°.

[0064] In this embodiment, the electrode lead (1200) may be an anode lead (1200a) and a cathode lead (1200b). The anode lead (1200a) and the cathode lead (1200b) may each extend in the same direction from one side of the electrode assembly, or they may each extend in different directions from one side and the other side of the electrode assembly.

[0065] The positive lead (1200a) and the negative lead (1200b) may be made of different materials. That is, the positive lead (1200a) may be made of the same aluminum material as the positive member (1111), and the negative lead (1200b) may be made of the same copper material as the negative member (1112) or nickel-coated copper material. Additionally, a portion of the electrode leads (1200; 1200a, 1200b) extending outside the battery case (1500) may be electrically connected to an external terminal.

[0066] As illustrated in FIG. 5, the electrode lead (1200) can be joined to the electrode tab portion (1120). More specifically, the connecting portion (1210) of the electrode lead (1200) and the electrode tab portion (1120) can be joined by a method such as spot welding. In this embodiment, the electrode lead (1200) may be a positive lead joined to the positive electrode tab portion (1121A) and a negative lead joined to the negative electrode tab portion (1122A).

[0067] In this embodiment, the connecting portion (1210) of the electrode lead (1200) can be joined to the lower side of the electrode tab portion (1120). When joining the connecting portion (1210) and the electrode tab portion (1120), the connecting portion (1210) can be positioned in a direction perpendicular to one end surface of the electrode assembly (1100), and the leading portion (1220) can be positioned in a direction parallel to one end surface of the electrode assembly (1100). The connecting portion (1210) is positioned to the lower side of the electrode tab portion (1120), and welding, etc., can be performed on the upper side of the electrode tab portion (1120), i.e., on side A. Accordingly, the connecting portion (1210) and the electrode tab portion (1120) can be joined.

[0068] After joining the connecting portion (1210) and the electrode tab portion (1120), the electrode lead (1200) can be rotated 90° upward (direction B) (Fig. 6). The electrode lead (1200) can be rotated so that the joined electrode tab portion (1120) faces one side of the electrode assembly (1100). Due to the rotation of the electrode lead (1200), the electrode tab portion (1120) is bent, and the lead portion (1220) becomes perpendicular to one side of the electrode assembly (1100). Due to the bending of the electrode tab portion (1120), the space occupied by the electrode tab portion (1120) within the battery case (1500) is reduced, and accordingly, the energy density can be increased.

[0069] In this embodiment, the connecting portion (1210) of the electrode lead (1200) is joined to the lower side of the electrode tab portion (1120), but is not limited thereto and in other embodiments, the connecting portion (1210) may be joined to the upper side of the electrode tab portion (1120). In this case as well, the electrode lead (1200) may be rotated 90° so that the joined electrode tab portion (1120) faces one side of the electrode assembly (1100). Due to the rotation of the electrode lead (1200), the lead portion (1220) of the electrode lead (1200) may be located at the center of the electrode assembly (1100) along the thickness direction of the electrode assembly (1100).

[0070] When joining the connecting part (1210) and the electrode tab part (1120), it is preferable to align the end of the connecting part (1210) and the end of the electrode tab part (1120). If the end of the connecting part (1210) and the end of the electrode tab part (1120) do not align, a step difference occurs at the joint between the connecting part (1210) and the electrode tab part (1120), and the battery case (1500) may be damaged due to this step difference.

[0071] The insulating portion (1300) is positioned on one side of the lead portion (1220) of the electrode lead (1200) and can wrap around a portion of the electrode lead (1200). The lead portion (1220) is drawn out to the outside of the battery case (1500), and the insulating portion (1300) is positioned at a location where the battery case (1500) is heat-fused. By means of the insulating portion (1300), the electrode lead (1200) can be drawn out to the outside of the battery case (1500) without contacting the battery case (1500). Accordingly, the insulating portion (1300) prevents electricity generated from the electrode assembly (1100) from flowing to the battery case (1500) through the electrode lead (1200) and can maintain the sealing of the battery case (1500). The insulating part (1300) is easy to attach to the electrode lead (1200) and mainly uses insulating tape with a relatively thin thickness, but is not limited to this and can use various materials capable of insulating the electrode lead (1200).

[0072] The insulating portion (1300) has a width (Wi) greater than the width of the electrode lead (1200) for the protection of the electrode lead (1200). Additionally, it is formed with a width greater than the width of the heat-sealed surface at the corner of the battery case (1500).

[0073] The fixing unit (1400) fixes the bent electrode tab portion (1120) and the electrode lead (1200). Due to the properties of the metal, the bent electrode tab portion (1120) tends to return to its original shape. If the electrode tab portion (1120) is unfolded and restored, the space occupied by the electrode tab portion (1120) within the battery case increases, and the battery case may be torn by the edges of the electrode tab portion (1120). Additionally, there is a problem that the defect rate of the manufactured secondary battery increases because the withdrawal direction of the electrode lead (1200) is not aligned in a certain direction. The fixing unit (1400) of the present invention fixes the bent electrode tab portion (1120) and the electrode lead (1200) to maintain the electrode tab portion (1120) in a bent state.

[0074] Even if the electrode tab portion (1120) and the electrode lead (1200) are formed with a wide width, the present invention can stably fix the electrode tab portion (1120) and the electrode lead (1200) by the fixing unit (1400).

[0075] The battery case (1500) is a pouch manufactured by forming a pouch film having a flexible material that accommodates an electrode assembly (1100) inside. Hereinafter, the battery case (1500) is described as a pouch. When a flexible pouch film (P) is drawn using a punch and a die, a portion of it is stretched to form a pocket-shaped receiving space.

[0076] A battery case (1500) may accommodate and seal an electrode assembly (1100) such that a portion of the electrode lead (1200) is exposed to the outside. The battery case (1500) may include a first case (1510) and a second case (1520). A first electrode assembly receiving portion (1511) may be formed in the first case (1510). A second electrode assembly receiving portion (1521) is formed in the second case (1520). An electrode assembly is accommodated within the first and second electrode assembly receiving portions (1511, 1521). The electrode assembly (1100) can be cased by receiving the electrode assembly (1100) in the first electrode assembly receiving portion (1511), covering the second case (1520) toward the first case (1510), and sealing the edges of the first and second cases (1510, 1520). The first case (1510) and the second case (1520) may be manufactured with one side connected to the other as shown in FIG. 1, but are not limited thereto and may be manufactured in various ways, such as being separated from each other and manufactured separately.

[0077] Bump regions (1512, 1522) may be formed at both ends of the electrode assembly receiving portions (1511, 1521). The bump regions (1512, 1522) are areas where the fixing unit (1400) and the lead are positioned when the electrode assembly (1100), in which the electrode lead (1200) is fixed by the fixing unit (1400), is received in the first electrode assembly receiving portion (1511) and the second electrode assembly receiving portion (1521). The bump regions (1512, 1522) are formed as concave surfaces so that the inner wall surface in contact with the fixing unit (1400) aligns with the outer surface of the fixing unit (14400). The bump regions (1512, 1522) casing the electrode assembly (1100) and serving to support the fixing unit (1400) so that it does not detach from one end of the electrode assembly (1100). In this embodiment, the thickness of the bump regions (1512, 1522) is formed to be the same as the thickness of the battery case (1500), but is not limited thereto, and the inner wall of the bump regions (1512, 1522) may be formed to be thicker than the thickness of the battery case (1500).

[0078] The bump area (1512, 1522) can be located in the center of the battery case along the width direction of the electrode assembly.

[0079] When forming electrode assembly receiving portions (1511, 1521) on a pouch film (P), only one electrode assembly receiving portion (1511, 1521) may be formed on a single pouch film, but is not limited thereto, and two electrode assembly receiving portions may be drawn and formed adjacent to each other on a single pouch film. The electrode assembly receiving portions (1511, 1521) formed on the first case (1510) and the second case (1520) may have the same depth, but are not limited thereto, and may have different depths.

[0080] FIG. 7 is a drawing showing a fixed unit of a secondary battery according to an embodiment of the present invention, FIG. 8 is a drawing showing a cross-section of a fixed unit of a secondary battery according to an embodiment of the present invention, FIG. 9 is a drawing showing the process of an electrode lead extraction portion penetrating a slit of a fixed unit in a secondary battery according to an embodiment of the present invention, FIG. 10 is a side cross-sectional view of a secondary battery according to an embodiment of the present invention in a state where an electrode tab portion and an electrode lead are fixed by a fixed unit, FIG. 11 is a drawing showing a fixed unit of a secondary battery according to an embodiment of the present invention.

[0081] For convenience of explanation, the explanation is based on the case where the bending direction of the electrode tab portion (1120) of the electrode assembly (1100) faces downward.

[0082] As shown in FIGS. 7 and 8, the fixed unit (1400) is equipped with an upper bracket (1410) and a lower bracket (1420), a pair of joints (1430), and a slit (1440).

[0083] The upper bracket (1410) is provided with a first pressure surface (1411) and a first opposing surface (1412). The first pressure surface (1411) is a surface that contacts the bent electrode tab portion (1120) when the fixed unit (1400) and the electrode assembly (1100) are combined. A concave surface may be formed on the first pressure surface (1411) to correspond to the curved electrode tab portion (1120). The first pressure surface (1411) supports the electrode tab portion (1120) to maintain its bent shape. An adhesive material may be applied to the first pressure surface (1411) so that it can be fixed to the electrode tab portion (1120).

[0084] The first opposing surface (1412) is the lower surface of the upper bracket (1410) and is a surface facing one side of the lead portion (1200) of the electrode lead (1200) when combined with the electrode assembly (1100). The length of the first opposing surface (1412) may be equal to or greater than the width (Wc) of the lead portion. By positioning the first opposing surface (1412) adjacent to the lead portion (1220) of the electrode lead (1200), the electrode lead (1200) may be prevented from being displaced beyond a predetermined range.

[0085] The lower bracket (1420) is provided with a second pressure surface (1421) and a second opposing surface (1422). The second pressure surface (1421) is a surface that contacts the connecting portion (1210) of the electrode lead (1200) when the fixed unit (1400) and the electrode assembly (1100) are combined. The second pressure surface (1421) presses the other side of the connecting portion (1210), on which the electrode tab portion (1120) is attached, thereby preventing the electrode tab portion (1120) from unfolding due to a restoring force. The second pressure surface (1421) may have a flat surface like the connecting portion (1210). The bent shape of the electrode tab portion (1120) is maintained by the first pressure surface (1411) and the second pressure surface (1421), and the electrode lead (1200) can maintain a constant shape without tilting or shaking due to external force. An adhesive material may be applied to the second pressure surface (1421) so that it can be fixed to the connecting part (1210).

[0086] The second opposing surface (1422) is the upper surface of the lower bracket (1420) and is a surface facing the other side of the lead portion (1220) of the electrode lead (1200) when the electrode assembly (1100) and the fixing unit (1400) are assembled. The length of the second opposing surface (1422) may be equal to or greater than the width (Wc) of the lead portion. By positioning the second opposing surface (1422) adjacent to the lead portion (1220) of the electrode lead (1200), the electrode lead (1200) may be prevented from being displaced beyond a predetermined range.

[0087] A pair of joints (1430) connect the upper bracket (1410) and the lower bracket (1420). The pair of joints (1430) are formed at a predetermined height and can be positioned between both ends of the upper bracket (1410) and the lower bracket (1420). By means of the pair of joints (1430), the upper bracket (1410) and the lower bracket (1420) can be connected with a portion of their length separated by a predetermined distance (d). The distance (d) between the upper bracket (1410) and the lower bracket (1420) can be greater than the thickness of the lead portion (1220) of the electrode lead (1200).

[0088] The slit (1440) is an opening defined by the upper bracket (1410), the lower bracket (1420), and a pair of joints (1430). The lead portion (1220) of the electrode lead can be drawn out into the slit (1440).

[0089] A fixing unit (1400) is positioned at one end of an electrode assembly (1100), and as shown in FIGS. 9 and 10, a slit (1440) is fitted into the lead portion (1220) of the electrode lead (1200), so that the first pressure surface (1410) and the second pressure surface (1420) of the fixing unit (1400) come into contact with the bent electrode tab portion (1120) and the connecting portion (1210), respectively. Accordingly, the fixing unit (1400) is joined to the electrode tab portion (1120) and the electrode lead (1200) to fix the bent electrode tab portion (1120) and the electrode lead (1200). The electrode lead (1200) can be inserted into a pouch in a state perpendicular to the electrode assembly (1100) by the fixing unit (1400).

[0090] Meanwhile, the upper bracket (1410), lower bracket (1420), a pair of joints (1430), and slit (1440) of the fixed unit (1400) can be formed integrally. For example, the fixed unit (1400) can be injection molded integrally from an insulating material such as PP.

[0091] The first opposing surface (1412) and the second opposing surface (1422) are spaced apart by a predetermined distance (d). The distance (d) between the first opposing surface (1412) and the second opposing surface (1422) defines the width of the slit (1440). For the placement of the fixed unit (1400), the pull-out portion (1220) and the insulating portion (1300) wrapped around the pull-out portion (1220) must pass through the slit (1440). To this end, the distance (d) between the first opposing surface (1412) and the second opposing surface (1422), i.e., the width of the slit (1440), can be formed to be greater than the thickness of the pull-out portion (1220). By forming the width of the slit (1440) to be greater than the thickness of the extraction portion (1220) and the insulating portion (1300) surrounding the extraction portion (1220), the extraction portion (1220) and the insulating portion (1300) can easily pass through the slit (1440).

[0092] Additionally, so that the lead portion (1220) and the insulating portion (1300) can easily pass through the slit (1440), the length (Ls) of the slit (1440) may be formed to be larger than the width (Wi) of the insulating portion (1300) (Fig. 11). For example, the length (Ls) of the slit (1440) may be formed to be 2 to 4 mm longer than the width (Wi) of the insulating portion (1300). When a fixing unit (1400) is placed at one end of the electrode assembly (1100), the lead portion (1220) is spaced apart from the slit (1440) by a predetermined distance.

[0093] The lead portion (1220) of the electrode lead (1200) is drawn out through the slit (1440), and the first pressure surface (1411) and the second pressure surface (1421) respectively contact and support the electrode tab portion (1120) and the connecting portion (1210), thereby allowing the electrode lead (1200) to be integrated with the fixed unit (1400).

[0094] Meanwhile, inclined surfaces may be formed at both ends of the upper bracket (1410) and the lower bracket (1420) so as not to impact the battery case (1500). Additionally, the corners of the upper bracket (1410) and the lower bracket (1420) may be formed as smooth curved surfaces. Due to the inclined surfaces and the curved corners of the upper bracket (1410) and the lower bracket (1420), the battery case (1500) is not torn or damaged even by the protrusion of the fixing unit (1400).

[0095] FIG. 12 is a drawing showing an electrode assembly in a secondary battery according to one embodiment of the present invention being cased by a battery case, and FIG. 13a and FIG. 13b are cross-sectional views of an electrode assembly in a secondary battery according to one embodiment of the present invention being cased by a battery case.

[0096] As illustrated in FIG. 12, after the electrode assembly (1100) is received in the electrode assembly receiving portion (1511) formed in the first case (1510), the second case (1520) can be folded so that the two electrode assembly receiving portions (1511, 1521) face each other. By doing so, the electrode assembly (1100) is received within the two electrode assembly receiving portions (1511, 1521). Since the first and second electrode assembly receiving portions (1511, 1521) facing each other receive a single electrode assembly (1100), a thicker electrode assembly can be received than when there is only one electrode assembly receiving portion. Additionally, when the first case (1510) and the second case (1520) are integrally connected to each other, the number of sides to be sealed can be reduced when performing a sealing process later. Therefore, the process speed can be improved, and the number of sealing processes can be reduced.

[0097] Bump regions (1512, 1513) are formed at both ends of the electrode assembly receiving portion (1511). The bump regions (1512, 1513) are areas where the fixed unit (1400) and the electrode lead (1200) being drawn out are placed when the electrode assembly (1100), with the electrode lead (1200) fixed thereto, is received in the first electrode assembly receiving portion (1511). The assembly of the fixed unit (1400) combined with the electrode tab portion (1120) and the electrode lead (1200) protrudes beyond the cross-section of the electrode assembly (1100). In the case of a rectangular pouch, due to the protruding part of the electrode assembly structure, a portion is created that cannot be cased in close contact with the electrode assembly (1100). The bump area (1512, 1513) is formed along the shape of the fixed unit (1400) of the electrode assembly (1100) so that the electrode assembly (1100) can be received and sealed in close contact with the pouch (1500).

[0098] As illustrated in FIGS. 13a and 13b, a first bump region (1512) is formed at one end of the first electrode assembly receiving portion (1511). The first bump region (1512) has an inner surface shape that matches the outer surface of the upper bracket (1410) of the fixing unit (1400).

[0099] Likewise, a second bump region (1522) is formed at both ends of the second electrode assembly receiving portion (1521). The second bump region (1522) has an inner surface shape that matches the outer surface of the lower bracket (1420) of the fixed unit (1400). The first bump region (1512) of the first electrode assembly receiving portion (1511) and the second bump region (1522) of the second electrode assembly receiving portion (1521) may have a symmetrical shape with respect to the slit from which the electrode lead (1200) is drawn, that is, with respect to the center of the thickness direction of the electrode assembly (1100).

[0100] In another embodiment, the inner wall forming the first and second bump regions (1512, 1522) may be formed to be thicker than the thickness of other regions of the battery case (1500). For example, the thickness of the inner wall of the bump region (1512, 1522) may be 2 to 3 times the thickness of other regions of the battery case (1500) (Fig. 13b). By forming the inner wall of the bump region (1512, 1522) thickly, the fixing unit (1400) and the electrode lead (1200) can be supported more stably. The inner wall of the bump region (1512, 1522) may be formed of the same material as the battery case (1500), but is not limited thereto and may be formed of a different material from the battery case (1500). For example, the inner wall of the bump region (1512, 1522) may be formed of an insulating material with a predetermined thickness. A pad made of insulating material may be attached to the inner wall of the bump area (1512, 1522). Alternatively, a pad made of heat dissipation material may be attached to the inner wall of the bump area (1512, 1522).

[0101] The first and second bump regions (1512, 1522) may be formed as concave surfaces so that the surface in contact with the fixed unit (1400) aligns with the outer surface of the fixed unit (1400). The first and second bump regions (1512, 1522) casing the electrode assembly (1100) and serving to support the fixed unit (1400) so that it does not detach from one end of the electrode assembly (1100).

[0102] Meanwhile, the battery case (1500) may include a degassing section (not shown) formed on the side of the electrode assembly receiving section (1511, 1521) that accommodates the electrode assembly (1100) and discharges gas generated inside the electrode assembly receiving section (1511, 1521) through a degassing hole (not shown). After housing the electrode assembly (1100) in the electrode assembly receiving section (1511, 1521) of the battery case (1500) and injecting an electrolyte, an activation process is performed, and gas is generated inside the battery case (1500), and a degassing process is performed to discharge this gas to the outside through the degassing section.

[0103] When the degassing process is completed, the degassing portion protruding to the side is removed, and the remaining side is folded at least once and fixed to the side of the battery case (1500) with tape.

[0104] FIG. 14 is a flowchart illustrating a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0105] As illustrated in FIG. 14, to manufacture a secondary battery according to an embodiment of the present invention, an electrode assembly is prepared (S3100). The electrode assembly (1100) comprises an electrode portion (1110) and an electrode tab portion (1120). The electrode portion (1110) comprises a plurality of unit electrode members (1111, 1112) and a separator (1113). The electrode portion (1110) of the electrode assembly (1100) can be formed by positioning a separator (1113) between an anode member (1111) and a cathode member (1112) that are alternately arranged. In one embodiment, the electrode portion (1110) is formed by alternately stacking the anode member (1111), the separator (1113), the cathode member (1112), and the separator (1113). Accordingly, the electrode assembly (1100) can have a rectangular shape having a height (H) and a width (W). In another embodiment, the electrode portion (1110) may be formed by arranging the positive electrode member (1111), the separator (1113), and the negative electrode member (1112) in that order and then winding them up.

[0106] A plurality of unit electrode members (1111, 1112) have a non-active tab (1121, 1122) formed thereon without an active material. In this embodiment, a non-active tab (1121) may be formed at one end of the positive electrode member (1111), and a non-active tab (1122) may be formed at the other end of the negative electrode member (1112) opposite to the one end, but is not limited thereto. The unit electrode members (1111, 1112) and the non-active tab (1121, 1122) may be formed integrally.

[0107] The non-existent tabs (1121) of the positive electrode member (1111) overlap each other at a first position, and the non-existent tabs (1122) of the negative electrode member (1112) overlap each other at a second position. Multiple non-existent tabs (1121, 1122) overlapped at the same position can be connected to each other by ultrasonic welding, laser welding, etc., to facilitate the movement of current, thereby forming an electrode tab portion (1120; 1121A, 1122A).

[0108] Next, the connection portion and the electrode tab portion of the electrode lead are joined (S3200). The electrode lead (1200) is joined to the electrode tab portion (1120). The electrode lead (1200) is provided with a connection portion (1210) and an extraction portion (1220). The connection portion (1210) and the electrode tab portion (1120) of the electrode lead (1200) can be joined by a method such as spot welding.

[0109] The connecting portion (1210) of the electrode lead (1200) can be joined to the lower side of the electrode tab portion (1120). When joining the connecting portion (1210) and the electrode tab portion (1120), the connecting portion (1210) can be positioned in a direction perpendicular to one end surface of the electrode assembly (1100), and the leading portion (1220) can be positioned in a direction parallel to one end surface of the electrode assembly (1100). The connecting portion (1210) and the electrode tab portion (1120) can be joined by performing welding or the like on the upper surface of the electrode tab portion (1120).

[0110] The electrode lead joined to the electrode tab portion is rotated 90° (S3300). The electrode lead (1200) can be rotated so that the joined electrode tab portion (1120) faces one side of the electrode assembly (1100). Due to the rotation of the electrode lead (1200), the electrode tab portion (1120) is bent, and the lead portion (1220) becomes perpendicular to one side of the electrode assembly (1100). Due to the bending of the electrode tab portion (1120), the space occupied by the electrode tab portion (1120) within the battery case (1500) is reduced, and the energy density can be increased accordingly.

[0111] An insulating portion is positioned to surround a portion of the lead portion (S3400). The insulating portion (1300) surrounds a portion of the electrode lead (1200). The insulating portion (1300) is positioned on one side of the lead portion (1220) of the electrode lead (1200).

[0112] The extraction portion (1220) is drawn out to the outside of the battery case (1500), and the insulating portion (1300) is positioned at a location where the battery case (1500) is heat-fused. By means of the insulating portion (1300), the electrode lead (1200) can be drawn out to the outside of the battery case (1500) without contacting the battery case (1500). Accordingly, the insulating portion (1300) prevents electricity generated from the electrode assembly (1100) from flowing to the battery case (1500) through the electrode lead (1200) and can maintain the sealing of the battery case (1500). The insulating portion (1300) mainly uses insulating tape that is easy to attach to the electrode lead (1200) and has a relatively thin thickness, but is not limited thereto and various materials capable of insulating the electrode lead (1200) can be used.

[0113] The insulating portion (1300) has a length greater than the width of the electrode lead (1200) to protect the electrode lead (1200). Additionally, it is formed with a width greater than the width of the heat-sealed surface at the corner of the battery case (1500).

[0114] A fixing unit is attached to one end of the electrode assembly (S3500). The fixing unit (1400) fixes the bent electrode tab portion (1120) and the electrode lead (1200).

[0115] The fixed unit (1400) is provided with an upper bracket (1410), a lower bracket (1420), a pair of joints (1430), and a slit (1440). The upper bracket (1410), the lower bracket (1420), the pair of joints (1430), and the slit (1440) are formed integrally. The lead portion (1220) of the electrode lead (1200) attached to the electrode assembly (1100) is allowed to pass through the slit (1440) so that the fixed unit (1400) is coupled to one side of the electrode assembly (1100).

[0116] The electrode tab portion (1120) and the connecting portion (1210), which are bent by the first pressure surface (1411) and the second pressure surface (1421) of the fixed unit (1400), are respectively compressed. Accordingly, the bent shape of the electrode tab portion (1120) is maintained, and the electrode lead (1200) can maintain a constant shape without tilting or shaking due to external force.

[0117] The displacement of the electrode lead can be maintained within a predetermined range by the first opposing surface of the upper bracket and the second opposing surface of the lower bracket.

[0118] An electrode assembly is housed within a battery case (S3600). The battery case (1500) houses and seals the electrode assembly (1100) such that a portion of the electrode lead (1200) is exposed to the outside.

[0119] The battery case (1500) includes a first case (1510) and a second case (1520). A first electrode assembly receiving portion (1511) is formed in the first case (1510). A second electrode assembly receiving portion (1521) is formed in the second case (1520). An electrode assembly is received within the first and second electrode assembly receiving portions (1511, 1521). An electrode assembly (1100) can be cased by receiving the electrode assembly (1100) in the first electrode assembly receiving portion (1511), covering the second case (1520) toward the first case (1510), and sealing the edges of the first and second cases (1510, 1520).

[0120] Although an embodiment of the present invention has been described above, those skilled in the art may modify and change the present invention in various ways by adding, changing, deleting, or adding components, etc., without departing from the spirit of the present invention as described in the claims, and such modifications and changes are also to be included within the scope of the rights of the present invention.

Claims

1. An electrode assembly having an electrode portion and an electrode tab portion formed at one end of the electrode portion and bent in one direction; An electrode lead having a connecting portion and a pull-out portion that is bent and extended relative to the connecting portion, wherein the connecting portion is welded to the electrode tab portion; and A fixing unit disposed at one end of the electrode assembly, comprising: an upper bracket having a first pressure surface and a first opposing surface; a lower bracket having a second pressure surface and a second opposing surface; a pair of joints connecting the upper bracket and the lower bracket; and a slit defined by the upper bracket, the lower bracket, and the pair of joints. A secondary battery characterized in that the lead portion of the electrode lead is fitted into the slit.

2. In Paragraph 1, A secondary battery characterized in that the upper bracket, the lower bracket, and the pair of joints are integrally molded.

3. In Paragraph 1 or 2, A secondary battery characterized by further including an insulating portion surrounding a part of the above-mentioned lead portion.

4. In Paragraph 1 or 2, A first case having a first electrode assembly receiving portion and a first bump region formed at least one end of the first electrode assembly receiving portion, and The battery case further comprises a second electrode assembly receiving portion and a second case having a second bump region formed at least one end of the second electrode assembly receiving portion. A secondary battery characterized in that the electrode assembly is received in the first electrode assembly receiving portion and the second electrode assembly receiving portion.

5. In Paragraph 4, A secondary battery characterized in that the above-mentioned extraction portion extends outside the battery case.

6. In Paragraph 1 or 2, A secondary battery characterized by the electrode tab portion being pre-welded.

7. In Paragraph 1 or 2, A secondary battery characterized in that the first opposing surface of the upper bracket faces one side of the lead portion, and the second opposing surface of the lower bracket faces the other side of the lead portion.

8. In Paragraph 1 or 2, A secondary battery characterized in that the first pressure surface of the upper bracket contacts the electrode tab portion, and the second pressure surface of the lower bracket contacts the connection portion.

9. In Paragraph 1 or 2, A secondary battery characterized in that the length of the first opposing surface is the same as the width (Wc) of the lead portion.

10. In Paragraph 1 or 2, A secondary battery characterized in that the distance (d) between the first opposing surface and the second opposing surface is greater than the thickness of the lead portion.

11. In Paragraph 3, A secondary battery characterized in that the length of the slit (Ls) is greater than the width (Wi) of the insulating portion.

12. In Paragraph 1 or 2, A secondary battery characterized by having inclined surfaces formed at both ends of the upper bracket and the lower bracket.

13. In Paragraph 1 or 2, A secondary battery characterized in that the width of the electrode tab portion is 40 to 70% of the width of the electrode assembly.

14. In Paragraph 1 or 2, A secondary battery characterized in that the above-mentioned lead portion is perpendicular to one end surface of the electrode assembly.

15. In Paragraph 3, A secondary battery characterized in that the inner walls of the first bump region and the second bump region are made of the same material as the battery case.

16. In Paragraph 3, A secondary battery characterized in that the inner walls of the first bump region and the second bump region are made of a material different from the battery case.

17. In Paragraph 3, A secondary battery characterized in that the first bump region and the second bump region are symmetrical with respect to the center of the thickness direction of the electrode assembly.

18. In Paragraph 3, A secondary battery characterized in that the first bump region and the second bump region are located at the center of the battery case along the width direction of the electrode assembly.

19. In Paragraph 3, A secondary battery characterized in that the shape of the inner wall surface of the first bump region and the second bump region matches the outer surface of the upper bracket and the lower bracket, respectively.

20. In Paragraph 3, A secondary battery characterized in that the above-mentioned battery case is a pouch.

21. A preparation step for preparing an electrode assembly having an electrode portion and an electrode tab portion; A joining step of joining the connecting portion and the electrode tab portion of an electrode lead having a connecting portion and a lead portion extending vertically from the connecting portion; A rotation step of rotating the electrode lead joined to the electrode tab portion by 90°; and A method for manufacturing a secondary battery characterized by including a fixing unit coupling step of penetrating the lead portion through the slit of the fixing unit and positioning the fixing unit at one end of the electrode assembly.

22. In Paragraph 21, After the above rotation step, A method for manufacturing a secondary battery, further comprising an insulating portion placement step in which the insulating portion is arranged to surround a portion of the lead portion.

23. In Paragraph 21 or 22, A method for manufacturing a secondary battery, further comprising a packaging step of accommodating the electrode assembly within a battery case.

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