Rechargeable-battery battery

Abstract

A secondary battery according to one embodiment of the present invention comprises a case having an internal space with one end open, an electrode assembly disposed in the internal space of the case, and a cap plate coupled to the one end and having a first terminal portion and a second terminal portion electrically connected to the electrode assembly, wherein the electrode assembly has an uneven shape in the portion corresponding to the open end when viewed from a wide side, and may further include a first electrode lead disposed on one side of the electrode assembly and a second electrode lead disposed on the other side of the electrode assembly.

Description

Technology Field

[0001] The present invention relates to a secondary battery. Background Technology

[0003] Recently, prismatic lithium-ion batteries (secondary batteries) are being adopted in electric vehicles and Energy Storage Systems (ESS). Meanwhile, it is important to improve energy efficiency by increasing the size of the electrode assembly, particularly the electrode plate, which is housed within the prismatic case of the prismatic secondary battery.

[0004] To this end, the electrode assembly is configured by arranging rectangular electrode plates so as to overlap. However, space is required within the rectangular case to join the terminal portions of the electrode assembly and the cap plate, and this inevitably creates an inefficient space within the case.

[0005] Accordingly, there is a problem in that the energy density within the prismatic case of the prismatic secondary battery is reduced. The problem to be solved

[0007] The present invention provides a secondary battery capable of improving energy density within a rectangular case. means of solving the problem

[0009] A secondary battery according to one embodiment of the present invention comprises: a case having an internal space with one end open; an electrode assembly disposed in the internal space of the case; a cap plate coupled to the one end and having a first terminal portion and a second terminal portion electrically connected to the electrode assembly; a first electrode lead disposed on one side of the electrode assembly and connected to the first terminal portion by a first lead tab having a bent shape; and a second electrode lead disposed on the other side of the electrode assembly and connected to the second terminal portion by a second lead tab having a bent shape; wherein the electrode assembly has an uneven shape in a portion corresponding to the open end when viewed from a wide side, and the uneven shape has a concave portion and a convex portion, and the concave portion may be disposed at the lower part of at least one of the connection portion between the first terminal portion and the first lead tab and the connection portion between the second terminal portion and the second lead tab.

[0010] The above-mentioned concave portion may be located in the central portion of the electrode assembly.

[0011] The electrode assembly comprises a first electrode plate, a separator, and a second electrode plate, and the first electrode plate, the separator, and the second electrode plate may be stacked in the width direction of the case.

[0012] The first electrode lead is connected to the first electrode plate, and the second electrode lead can be connected to the second electrode plate.

[0013] The first terminal portion is electrically connected to the first electrode plate, and the second terminal portion is spaced apart from the first terminal portion and can be electrically connected to the second electrode plate.

[0014] The first and second lead tabs are provided with an insulating layer made of a material different from that of the case, and the insulating layer may be provided on one surface of the first and second lead tabs that is positioned opposite the inner surface of the case.

[0015] An insulating film may be disposed between the cap plate and the electrode assembly in an area excluding the area where the first and second terminal portions are disposed.

[0016] The above convex portion may be located in the central part of the electrode assembly.

[0017] The first terminal portion is electrically connected to the first electrode plate of the electrode assembly, the second terminal portion is spaced apart from the first terminal portion and is electrically connected to the second electrode plate of the electrode assembly, the first and second terminal portions are arranged in the central portion of the cap plate, and at least one of the connection portion between the first terminal portion and the first lead tab and the connection portion between the second terminal portion and the second lead tab may overlap with at least one of the central portion of the cap plate and the central portion of the electrode assembly.

[0018] An insulating film may be disposed between the cap plate and the electrode assembly in an area excluding the area where the first and second terminal portions are disposed.

[0019] A secondary battery according to another embodiment of the present invention comprises: a case having an internal space with one end open; an electrode assembly disposed in the internal space of the case and having a first electrode plate, a separator, and a second electrode plate; a cap plate coupled to the open end and having a first terminal portion electrically connected to the first electrode plate and a second terminal portion electrically connected to the second electrode plate; a first electrode lead disposed on one side of the electrode assembly and connected to the first terminal portion by a first lead tab having a bent shape; and a second electrode lead disposed on the other side of the electrode assembly and connected to the second terminal portion by a second lead tab having a bent shape; wherein, when viewed from a wide side, the electrode assembly has a convex shape in the portion disposed on the outer side of the first and second terminal portions among the portions corresponding to the open end, and a concave shape in the portion disposed corresponding to the first and second terminal portions, and the connection portion between the first terminal portion and the first lead tab and the connection portion between the second terminal portion and the second lead tab are the It can be positioned to correspond to the concave shape of the electrode assembly.

[0020] The first electrode plate, the separator, and the second electrode plate can be stacked in the width direction of the case.

[0021] delete Effects of the invention

[0022] The present invention has the effect of improving energy density within a rectangular case. Brief explanation of the drawing

[0024] FIG. 1 is a perspective view showing a secondary battery according to an exemplary embodiment of the present invention. FIG. 2 is a cross-sectional view showing a secondary battery according to an exemplary embodiment of the present invention. FIG. 3 is a perspective view showing an electrode assembly of a secondary battery according to an exemplary embodiment of the present invention. FIG. 4 is a perspective view showing a secondary battery according to an exemplary embodiment of the present invention. FIG. 5 is a cross-sectional view showing a secondary battery according to an exemplary embodiment of the present invention. FIG. 6 is a perspective view showing an electrode assembly of a secondary battery according to an exemplary embodiment of the present invention. Specific details for implementing the invention

[0025] Preferred embodiments of the present invention will be described below with reference to the attached drawings. However, embodiments of the present invention may be modified in various different forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. In the drawings, the shapes and sizes of elements may be exaggerated for clearer explanation.

[0027] FIG. 1 is a perspective view showing a secondary battery according to an exemplary embodiment of the present invention, FIG. 2 is a cross-sectional view showing a secondary battery according to an exemplary embodiment of the present invention, and FIG. 3 is a perspective view showing an electrode assembly of a secondary battery according to an exemplary embodiment of the present invention.

[0029] Referring to FIGS. 1 to 3, a secondary battery (100) according to an exemplary embodiment of the present invention may be configured to include, as an example, a case (110), an electrode assembly (120), and a cap plate (130).

[0031] The case (110) forms an internal space that accommodates an electrode assembly (120) and an electrolyte inside. As an example, the case (110) may have a rectangular shape with an open top. As such, since the top of the case (110) is open, the electrode assembly (120) can be inserted into the interior through the open top of the case (110). As an example, the case (110) may be made of a metal such as aluminum or stainless steel.

[0033] The electrode assembly (120) is placed in the internal space of the case (110). The electrode assembly (120) includes a first electrode plate (121), a second electrode plate (122), and a separator (123) formed in a thin plate or film shape, and can be formed in various shapes as needed, such as a laminated or wound shape. As an example, the first electrode plate (121) can act as a negative electrode, and the second electrode plate (122) can act as a positive electrode.

[0034] The first electrode plate (121) may be formed by applying a first electrode active material, such as graphite or carbon, to a first electrode current collector formed from a metal foil, such as copper, a copper alloy, nickel, or a nickel alloy. Additionally, the first electrode plate (121) includes a first electrode non-coated portion (121a), which is an area where the first electrode active material is not applied. The first electrode non-coated portion (121a) serves as a passage for current flow between the first electrode plate (121) and the outside of the first electrode plate (121). Meanwhile, the first electrode plate (121) may be provided with a first electrode lead (121b) connected to the first electrode non-coated portion (121a). As an example, the first electrode lead (121b) may be installed by joining it to the first electrode non-coated portion (121a) by welding. Additionally, the first electrode lead (121b) may be made of copper or a copper alloy. As an example, the first electrode lead (121b) is placed on one side of the electrode assembly (120).

[0035] The second electrode plate (122) may be formed by applying a second electrode active material, such as a transition metal oxide, to a second electrode current collector formed from a metal foil, such as aluminum or an aluminum alloy, for example. Additionally, the second electrode plate (122) includes a second electrode non-existent portion (not shown), which is an area where the second electrode active material is not applied. The second electrode non-existent portion also serves as a passage for current flow between the second electrode plate (122) and the outside of the second electrode plate (122). Meanwhile, the second electrode plate (122) may be provided with a second electrode lead (122b) connected to the second electrode non-existent portion. As an example, the second electrode lead (122b) may be installed by joining it to the second electrode non-existent portion by welding. Additionally, the second electrode lead (122b) may be made of aluminum or an aluminum alloy. As an example, the second electrode lead (122b) is placed on the other side of the electrode assembly (120).

[0036] The separator (123) is positioned between the first electrode plate (121) and the second electrode plate (122) to prevent short circuits and enable the movement of lithium ions. For example, the separator (123) may be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. As an example, the separator (123) may be placed one sheet at a time between the first and second electrode plates (121, 122), or a single separator (123) may be alternately folded from one side and the other side and inserted between multiple first and second electrode plates (121, 122). In other words, the separator (123) may be made of multiple sheets or may be composed of a single separator (123). However, it is not limited thereto, and the separator (123) may be varied in many ways as long as it is positioned between the first and second electrode plates (121, 122) to prevent short circuits and enable the movement of lithium ions.

[0037] Meanwhile, the first electrode plate (121), the second electrode (122), and the separator (123) can be arranged in the width direction (Y-axis direction of FIG. 1) of the case (110). Accordingly, the volume occupied by the electrode assembly (120) within the case (110) can be increased, thereby improving energy efficiency. Additionally, while the first electrode plate (121), the second electrode (122), and the separator (123) are arranged in the width direction (Y-axis direction of FIG. 1) of the case (110), the first and second electrode leads (121b, 122b) are placed at both ends of the electrode assembly (120). Accordingly, space efficiency can be further improved, and the manufacturing yield can be improved by increasing the size of the stacked first and second electrode plates (121, 122) while reducing the number of stacked first and second electrode plates (121, 122). Here, when defining the terms for direction, the length direction refers to the X-axis direction of FIG. 1, and the height direction refers to the Z-axis direction of FIG. 1.

[0038] In other words, the electrode assembly (120) is formed such that the length in the longitudinal direction is greater than the length in the width direction and the length in the height direction.

[0039] Meanwhile, when the electrode assembly (120) is viewed from the front, that is, when viewing the part with the widest area of ​​the electrode assembly (120), the electrode assembly (120) has an uneven shape on its upper portion. For example, the uneven shape may have a convex shape in the center of the electrode assembly (120). And, the uneven shape with a convex center may have a rectangular shape when viewed from the front.

[0040] Accordingly, the energy density of the secondary battery (100) can be improved by increasing the size of the electrode assembly (120). In other words, the size of the electrode assembly (120) can be increased while reducing the empty space inside the case (110).

[0041] However, the uneven shape is not limited to a rectangular shape, and the uneven shape can be changed in various ways.

[0042] Meanwhile, the separator (123) may have a shape corresponding to the shape of the electrode assembly (120), or may have a rectangular shape sized to cover the convex uneven portion of the electrode assembly (120). When the separator (123) has a rectangular shape, the upper edge of the separator (123) placed outside the convex uneven portion may be pressed by the first and second terminal portions (131, 132) to be described later.

[0043] Meanwhile, the electrode assembly (120) is housed in a case (110) together with an electrolyte. The electrolyte may consist of a lithium salt such as LiPF6 or LiBF4 in an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), or dimethyl carbonate (DMC). Additionally, the electrolyte may be in the form of a liquid or a gel.

[0045] The cap plate (130) is attached to the upper part of the case (110) to seal the case (110). For example, the case (110) and the cap plate (130) may be formed of aluminum and welded together. Meanwhile, the cap plate (130) is provided with a first terminal portion (131) electrically connected to a first electrode plate (121) and a second terminal portion (132) spaced apart from the first terminal portion (131) and electrically connected to a second electrode plate (122). Additionally, the cap plate (130) may have an electrolyte injection port (133) and a vent hole (134) positioned between the first and second terminal portions (131, 132). The electrolyte injection port (133) serves to allow the electrolyte to be injected into the interior of the case (110) after the cap plate (130) is attached to the case (110). And, the electrolyte injection port (133) is sealed by a sealing plug (133a) after the electrolyte is injected.

[0046] The vent hole (134) is sealed with a vent plate (134a) to allow the internal pressure of the secondary battery (110) to be released. When the internal pressure of the secondary battery (110) reaches a set pressure, the vent plate (134a) is cut open to open the vent hole (134). As an example, the vent plate (134a) may be provided with a notch (134a-1) that induces the cut.

[0047] The first and second terminal portions (131, 132) can each be installed in the terminal hole (133) of the cap plate (130). Meanwhile, the first and second gaskets (134, 135) are placed between the first and second terminal portions (131, 132) and the terminal hole (133) to seal and electrically insulate the first and second terminal portions (131, 132) and the cap plate (130).

[0048] In addition, the first and second gaskets (135, 136) prevent the electrolyte from leaking through the terminal holes by installing the first and second terminal portions (21, 22) on the cap plate (130).

[0049] The first and second lead tabs (141, 142) electrically connect the first and second terminal portions (131, 132) to the first and second electrode plates (121, 122) of the electrode assembly (120), respectively. That is, the first and second lead tabs (141, 142) can be joined and installed to the first and second terminal portions (131, 132) by welding.

[0050] Meanwhile, the first and second lead tabs (141, 142) may be provided with first and second insulating layers (141a, 142a) for insulation from the inner surface of the case (110). Accordingly, the first and second lead tabs (141, 142) and the case (110) can be electrically insulated.

[0051] For example, the first and second lead tabs (141, 142) may have a bent shape to connect the first and second electrode leads (121b, 122b), which are positioned to protrude from both sides of the electrode assembly (120), to the first and second terminal portions (131, 132) of the cap plate (130).

[0052] Meanwhile, an insulating film (150) for insulating the electrode assembly (120) and the cap plate (130) may be disposed between the electrode assembly (120) and the cap plate (130). The insulating film (150) may be provided with a through hole (not shown) through which the first and second terminal portions (131, 132) pass.

[0054] As described above, a space for welding the first and second terminal portions (131, 132) and the first and second lead tabs (141, 142) provided on the cap plate (130) is formed inside the case (110). However, since the electrode assembly (120) is provided with a convex portion having an uneven shape so as to be placed between the first and second terminal portions (131, 132), the energy density can be improved.

[0056] FIG. 4 is a perspective view showing a secondary battery according to an exemplary embodiment of the present invention, FIG. 5 is a cross-sectional view showing a secondary battery according to an exemplary embodiment of the present invention, and FIG. 6 is a perspective view showing an electrode assembly of a secondary battery according to an exemplary embodiment of the present invention.

[0058] Referring to FIGS. 4 to 6, a secondary battery (200) according to an exemplary embodiment of the present invention may be configured to include, as an example, a case (210), an electrode assembly (220), and a cap plate (230).

[0060] The case (210) forms an internal space that accommodates an electrode assembly (220) and an electrolyte inside. As an example, the case (210) may have a rectangular shape with an open top. As such, since the top of the case (210) is open, the electrode assembly (220) can be inserted into the interior through the open top of the case (210). As an example, the case (210) may be made of a metal such as aluminum or stainless steel.

[0062] The electrode assembly (220) is placed in the internal space of the case (210). The electrode assembly (220) includes a first electrode plate (221), a second electrode plate (222), and a separator (223) formed in a thin plate or film shape, and can be formed in various shapes as needed, such as a laminated or wound shape. As an example, the first electrode plate (221) can act as a negative electrode, and the second electrode plate (222) can act as a positive electrode.

[0063] The first electrode plate (221) may be formed by applying a first electrode active material, such as graphite or carbon, to a first electrode current collector formed from a metal foil, such as copper, a copper alloy, nickel, or a nickel alloy. Additionally, the first electrode plate (221) includes a first electrode non-coated portion (221a), which is an area where the first electrode active material is not applied. The first electrode non-coated portion (221a) serves as a passage for current flow between the first electrode plate (221) and the outside of the first electrode plate (221). Meanwhile, the first electrode plate (221) may be provided with a first electrode lead (221b) connected to the first electrode non-coated portion (221a). As an example, the first electrode lead (221b) may be installed by joining it to the first electrode non-coated portion (221a) by welding. Additionally, the first electrode lead (221b) may be made of copper or a copper alloy. As an example, the first electrode lead (221b) is positioned on one side of the electrode assembly (220).

[0064] The second electrode plate (222) may be formed by applying a second electrode active material, such as a transition metal oxide, to a second electrode current collector formed of a metal foil, such as aluminum or an aluminum alloy, for example. Additionally, the second electrode plate (222) includes a second electrode non-existent portion (not shown), which is an area where the second electrode active material is not applied. The second electrode non-existent portion also serves as a passage for current flow between the second electrode plate (222) and the outside of the second electrode plate (222). Meanwhile, the second electrode plate (222) may be provided with a second electrode lead (222b) connected to the second electrode non-existent portion. As an example, the second electrode lead (222b) may be installed by joining it to the second electrode non-existent portion by welding. Additionally, the second electrode lead (222b) may be made of aluminum or an aluminum alloy. As an example, the second electrode lead (222b) is disposed on the other side of the electrode assembly (220).

[0065] The separator (223) is positioned between the first electrode plate (221) and the second electrode plate (222) to prevent short circuits and enable the movement of lithium ions. For example, the separator (223) may be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene.

[0066] For example, the separator (223) may be placed one by one between the first and second electrode plates (221, 222), and a single separator (223) may be alternately folded from one side and the other side and inserted between multiple first and second electrode plates (221, 222). In other words, the separator (223) may be composed of multiple pieces or may be composed of a single separator (223). However, it is not limited thereto, and the separator (223) may be varied in various ways as long as it is placed between the first and second electrode plates (221, 222) to prevent short circuits and enable the movement of lithium ions.

[0067] Meanwhile, the first electrode plate (221), the second electrode (222), and the separator (223) can be arranged in the width direction (Y-axis direction of FIG. 1) of the case (210). Accordingly, the volume occupied by the electrode assembly (220) within the case (210) can be increased, thereby improving energy efficiency. Additionally, while the first electrode plate (221), the second electrode (222), and the separator (223) are arranged in the width direction (Y-axis direction of FIG. 1) of the case (210), the first and second electrode leads (221b, 222b) are placed at both ends of the electrode assembly (220). Accordingly, space efficiency can be further improved, and the manufacturing yield can be improved by increasing the size of the stacked first and second electrode plates (221, 222) while reducing the number of stacked first and second electrode plates (221, 222). Here, when defining the terms for direction, the length direction refers to the X-axis direction of FIG. 1, and the height direction refers to the Z-axis direction of FIG. 1.

[0068] In other words, the electrode assembly (220) is formed such that its length in the longitudinal direction is greater than its length in the width direction and its length in the height direction.

[0069] Meanwhile, when the electrode assembly (220) is viewed from the front, that is, when viewing the part with the widest area of ​​the electrode assembly (220), the electrode assembly (220) has an uneven shape on its upper portion. For example, the uneven shape may have a concave shape in the center of the electrode assembly (220). And, the uneven shape with a concave center may have a rectangular shape when viewed from the front.

[0070] Accordingly, the energy density of the secondary battery (200) can be improved by increasing the size of the electrode assembly (220). In other words, the size of the electrode assembly (220) can be increased while reducing the empty space inside the case (210).

[0071] However, the uneven shape is not limited to a rectangular shape, and the uneven shape can be changed in various ways.

[0072] Meanwhile, the separator (223) may have a shape corresponding to the shape of the electrode assembly (220), or may have a rectangular shape sized to cover the concave shape of the electrode assembly (220). When the separator (223) has a rectangular shape, the upper edge of the separator (223) placed inside the concave shape of the concave shape may be pressed by the first and second terminal parts (231, 232) to be described later.

[0073] Meanwhile, the electrode assembly (220) is housed in a case (210) together with an electrolyte. The electrolyte may consist of a lithium salt such as LiPF6 or LiBF4 in an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), or dimethyl carbonate (DMC). Additionally, the electrolyte may be in the form of a liquid or a gel.

[0075] The cap plate (230) is attached to the upper part of the case (210) to seal the case (210). For example, the case (210) and the cap plate (230) may be formed of aluminum and welded together. Meanwhile, the cap plate (230) is provided with a first terminal portion (231) electrically connected to a first electrode plate (221) and a second terminal portion (232) spaced apart from the first terminal portion (231) and electrically connected to a second electrode plate (222). Additionally, the cap plate (230) may have an electrolyte injection port (233) and a vent hole (234) positioned outside the first and second terminal portions (231, 232). The electrolyte injection port (233) serves to allow the electrolyte to be injected into the interior of the case (210) after the cap plate (230) is attached to the case (210). And, the electrolyte injection port (233) is sealed by a sealing plug (233a) after the electrolyte is injected.

[0076] The vent hole (234) is sealed with a vent plate (234a) to allow the internal pressure of the secondary battery (200) to be discharged. When the internal pressure of the secondary battery (200) reaches a set pressure, the vent plate (234a) is cut open to open the vent hole (234). As an example, the vent plate (234a) may be provided with a notch (234a-1) that induces the cut.

[0077] The first and second terminal portions (231, 232) can each be installed in the terminal hole (233) of the cap plate (230). Meanwhile, the first and second gaskets (234, 235) are placed between the first and second terminal portions (231, 232) and the terminal hole (233) to seal and electrically insulate the first and second terminal portions (231, 232) and the cap plate (230).

[0078] In addition, the first and second gaskets (235, 236) prevent the electrolyte from leaking through the terminal holes by installing the first and second terminal portions (231, 232) on the cap plate (230).

[0079] The first and second lead tabs (241, 242) electrically connect the first and second terminal portions (231, 232) to the first and second electrode plates (221, 222) of the electrode assembly (220), respectively. That is, the first and second lead tabs (241, 242) can be joined and installed to the first and second terminal portions (231, 232) by welding.

[0080] Meanwhile, the first and second lead tabs (241, 242) may be provided with first and second insulating layers (241a, 242a) for insulation from the inner surface of the case (210). Accordingly, the first and second lead tabs (241, 242) and the case (210) can be electrically insulated.

[0081] For example, the first and second lead tabs (241, 242) may have a bent shape to connect the first and second electrode leads (221b, 222b), which are positioned to protrude from both sides of the electrode assembly (220), to the first and second terminal portions (231, 232) of the cap plate (230).

[0082] Meanwhile, an insulating film (250) for insulating the electrode assembly (220) and the cap plate (230) may be disposed between the electrode assembly (220) and the cap plate (230). The insulating film (250) may be provided with a through hole (not shown) through which the first and second terminal portions (231, 232) pass.

[0084] As described above, a space for welding the first and second terminal portions (231, 232) and the first and second lead tabs (241, 242) provided on the cap plate (230) is formed inside the case (210). However, since the electrode assembly (220) is provided with a concave portion having an uneven shape positioned below the first and second terminal portions (231, 232), the energy density can be improved.

[0086] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be obvious to those skilled in the art that various modifications and variations are possible within the scope of the technical concept of the present invention as described in the claims. Explanation of the symbols

[0087] 100, 200 : Secondary battery 110, 210 : Case 120, 220 : Electrode assembly 130, 230: Cap plate

Claims

Claim 1 A secondary battery comprising: a case having an internal space with one end open; an electrode assembly disposed in the internal space of the case; a cap plate coupled to the one end and having a first terminal portion and a second terminal portion electrically connected to the electrode assembly; a first electrode lead disposed on one side of the electrode assembly and connected to the first terminal portion by a first lead tab having a bent shape; and a second electrode lead disposed on the other side of the electrode assembly and connected to the second terminal portion by a second lead tab having a bent shape; wherein the electrode assembly has an uneven shape in a portion corresponding to the open end when viewed from a wide side, the uneven shape has a concave portion and a convex portion, and the concave portion is disposed at the lower part of at least one of the connection portion between the first terminal portion and the first lead tab and the connection portion between the second terminal portion and the second lead tab. Claim 2 In claim 1, the concave portion is a secondary battery located in the central portion of the electrode assembly. Claim 3 In paragraph 2, the electrode assembly comprises a first electrode plate, a separator, and a second electrode plate, and the first electrode plate, the separator, and the second electrode plate are stacked in the width direction of the case, forming a secondary battery. Claim 4 In paragraph 3, the first electrode lead is connected to the first electrode plate, and the second electrode lead is connected to the second electrode plate, in a secondary battery. Claim 5 In paragraph 4, the first terminal portion is electrically connected to the first electrode plate, and the second terminal portion is spaced apart from the first terminal portion and electrically connected to the second electrode plate, forming a secondary battery. Claim 6 delete Claim 7 In claim 1, the first and second lead tabs are provided with an insulating layer made of a material different from that of the case, and the insulating layer is provided on one surface of the first and second lead tabs facing the inner surface of the case. Claim 8 A secondary battery according to claim 5, wherein an insulating film is disposed in an area between the cap plate and the electrode assembly, excluding the area where the first and second terminal portions are disposed. Claim 9 In claim 1, the convex portion is a secondary battery located in the central portion of the electrode assembly. Claim 10 A secondary battery according to claim 2 or 9, wherein the first terminal portion is electrically connected to the first electrode plate of the electrode assembly, the second terminal portion is spaced apart from the first terminal portion and is electrically connected to the second electrode plate of the electrode assembly, the first and second terminal portions are arranged in the central portion of the cap plate, and at least one of the connection portion between the first terminal portion and the first lead tab and the connection portion between the second terminal portion and the second lead tab overlaps with at least one of the central portion of the cap plate and the central portion of the electrode assembly. Claim 11 delete Claim 12 A secondary battery according to claim 1, wherein an insulating film is disposed in an area between the cap plate and the electrode assembly, excluding the area where the first and second terminal portions are disposed. Claim 13 A case having an internal space with one end open; an electrode assembly disposed in the internal space of the case and having a first electrode plate, a separator, and a second electrode plate; a cap plate coupled to the open end and having a first terminal portion electrically connected to the first electrode plate and a second terminal portion electrically connected to the second electrode plate; A secondary battery comprising: a first electrode lead disposed on one side of the electrode assembly and connected to the first terminal portion by a first lead tab having a bent shape, and a second electrode lead disposed on the other side of the electrode assembly and connected to the second terminal portion by a second lead tab having a bent shape; wherein, when viewed from a wide side, the electrode assembly has a convex shape in the portion disposed on the outer side of the first and second terminal portions among the portions corresponding to the open end, and a concave shape in the portion disposed corresponding to the first and second terminal portions, and the connection portion between the first terminal portion and the first lead tab and the connection portion between the second terminal portion and the second lead tab are disposed corresponding to the concave shape of the electrode assembly. Claim 14 In paragraph 13, the first electrode plate, separator, and second electrode plate are a secondary battery that is stacked in the width direction of the case.

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