Secondary batteries

Abstract

To provide a secondary battery with a short exhaust gas path.SOLUTION: A lithium ion battery 10 includes a flat winding body 40 in which an electrode sheet consisting of a positive electrode sheet and a negative electrode sheet is wound, a case 12 that accommodates the winding body 40, and a gas exhaust valve 70 provided at a position corresponding to the axial end of the winding body 40 of the case 12, and the gas exhaust valve 70 is provided at a position corresponding to the center of the winding body 40.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] In a secondary battery, it is known to provide a gas discharge valve in a case for housing an electrode body (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a configuration of a power storage module including a laminate in which bipolar electrodes including electrode plates, a positive electrode, and a negative electrode are laminated, a frame body provided with an opening communicating with a plurality of internal spaces, and a pressure regulating valve connected to the opening.

[0004] By the way, in a secondary battery, it is preferable to shorten the exhaust gas path.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In consideration of the above facts, an object of the present invention is to provide a secondary battery with a shortened exhaust gas path.

Means for Solving the Problems

[0007] The secondary battery according to the first aspect of the present invention includes a flat wound body in which an electrode sheet composed of a positive electrode sheet and a negative electrode sheet is wound, a case for housing the wound body, and a gas discharge valve provided at a position corresponding to an axial end portion of the wound body in the case, and the gas discharge valve is provided at a position corresponding to the center of the wound body.

[0008] In a secondary battery according to a second aspect of the present invention, the gas discharge valve is provided at positions corresponding to both axial ends of the winding body of the case, in the secondary battery according to the first aspect of the present invention.

[0009] In a secondary battery according to a third aspect of the present invention, in a secondary battery according to the first or second aspect of the present invention, the case for housing the winding body is formed to conform to the outer shape of the winding body, comprising a first case that contacts one long side surface of the winding body and a second case that contacts the other long side surface of the winding body.

[0010] In a secondary battery according to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, a current collector terminal is provided on one long side surface of the winding body, and a counter member is provided on the other long side surface of the winding body opposite to the current collector terminal, wherein the current collector terminal and the counter member are provided so as to avoid a position corresponding to the center of the winding body.

[0011] In a secondary battery according to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, a current collector terminal is provided on one long side surface of the winding body, and a counter member is provided on the other long side surface of the winding body opposite to the current collector terminal, wherein the counter member is formed by bending away from the winding body so as not to contact the central part of the winding body in the short direction. [Effects of the Invention]

[0012] In the secondary battery according to the first aspect of the present invention, the gas discharge valve is provided at a position corresponding to the center of the winding body, so that the gas generated at the center of the winding body is discharged from the winding body. Therefore, the exhaust gas path can be shortened.

[0013] In the secondary battery according to the second aspect of the present invention, the gas discharge valves are provided at positions corresponding to both axial ends of the winding body of the case, so that gas discharge valves are formed on both axial sides of the winding body. Therefore, regardless of which axial direction the gas generated in the winding body is discharged, the gas is discharged from the gas discharge valves. As a result, the exhaust gas path can be made shorter.

[0014] In a secondary battery according to a third aspect of the present invention, the case housing the winding body is formed to conform to the outer shape of the winding body, with a first case in contact with one long side surface of the winding body and a second case in contact with the other long side surface of the winding body, so that the winding body is held by the first case and the second case. As a result, misalignment of the gas discharge valve relative to the winding body is suppressed. Consequently, exhaust gas performance can be maintained.

[0015] In the secondary battery according to the fourth aspect of the present invention, the current collector terminal and the opposing member are positioned to avoid the position corresponding to the center of the winding body, so that the current collector terminal and the opposing member are not positioned in the gas passage between the winding body and the gas discharge valve. Therefore, the gas discharged from the winding body is discharged from the gas discharge valve without being obstructed by the current collector terminal and the opposing member. As a result, a decrease in exhaust gas efficiency can be suppressed.

[0016] In the secondary battery according to the fifth aspect of the present invention, the opposing member is formed by bending away from the winding body so as not to come into contact with the central part of the winding body in the short direction, so that the opposing member is not positioned in the gas passage between the winding body and the gas discharge valve. Therefore, the gas discharged from the winding body is discharged from the gas discharge valve without being obstructed by the opposing member. As a result, a decrease in exhaust gas efficiency can be suppressed. [Brief explanation of the drawing]

[0017] [Figure 1] This is a perspective view showing a lithium-ion battery according to this embodiment. [Figure 2] This is an exploded perspective view showing a lithium-ion battery according to this embodiment. [Figure 3]It is a cross-sectional view showing the lithium-ion battery according to this embodiment, and shows the A-A cross-section of FIG. 1. [Figure 4] It is a cross-sectional view showing the lithium-ion battery according to this embodiment, and shows the B-B cross-section of FIG. 1. [Figure 5] It is an exploded perspective view showing the current collector terminal and the opposing member according to this embodiment. [Figure 6] It is a cross-sectional view showing the lithium-ion battery according to this embodiment, and shows the H-H cross-section of FIG. 5. [Figure 7] It is a cross-sectional view showing the lithium-ion battery according to this embodiment, and shows the J-J cross-section of FIG. 5.

Mode for Carrying Out the Invention

[0018] Hereinafter, the secondary battery according to this embodiment will be described with reference to the drawings. The secondary battery according to this embodiment is, for example, a lithium-ion battery that constitutes a battery pack used as an in-vehicle power source for an electric vehicle, a hybrid vehicle, or the like. In each figure, arrow D indicates the longitudinal direction D of the lithium-ion battery 10, arrow E indicates the width direction E of the lithium-ion battery 10, and arrow F indicates the vertical direction F of the lithium-ion battery 10.

[0019] [Configuration of Lithium-Ion Battery 10] As shown in FIGS. 1 and 2, the lithium-ion battery 10 includes a case 12, a wound body 40 as an electrode body, a current collector terminal 50, and an opposing member 60.

[0020] (Case 20)[[ID=三十一]] As shown in FIG. 3, the case 12 is, for example, made of resin, and the first case 20 and the second case 30 form an accommodation space S for accommodating the wound body 40.

[0021] As shown in Figure 1, one side of the case 12 in the longitudinal direction D is fitted into the mounting groove 5A of the battery pack 5, which is the component to be mounted, and the case 12 is attached to the battery pack 5. The width W2 of one side of the case 12 in the longitudinal direction D is formed to be different from the width W1 of the other side of the case 12 in the longitudinal direction D. In other words, the case 12 is formed to have different thicknesses on the side where the positive electrode current collector terminal connected to the positive electrode sheet is located and on the side where the negative electrode current collector terminal connected to the negative electrode sheet is located.

[0022] <Case 1, 20> As shown in Figures 2 and 3, the first case 20 is formed in the shape of a rectangular box with a bottom wall 22, a first side wall 24, and a second side wall 26, with the other side in the width direction E being open.

[0023] The bottom wall portion 22 is formed in a rectangular plate shape with the width direction E being the plate thickness direction and extending in the longitudinal direction D.

[0024] The first side wall portion 24 is formed in pairs so as to rise from the upper and lower edges of the bottom wall portion 22 in the vertical direction F to the other side in the width direction E. The first side wall portion 24 is formed in the shape of a rectangular plate with the vertical direction F being the plate thickness direction and extending in the longitudinal direction D.

[0025] A first side wall portion 24, provided at the upper edge of the bottom wall portion 22 in the vertical direction F, has an elongated opening 24A that penetrates in the thickness direction. The opening 24A is formed on the other side of the longitudinal direction D from the center of the bottom wall portion 22 in the longitudinal direction D. A temperature sensing unit 72 for detecting the temperature inside the case 12 is provided in the opening 24A.

[0026] The second side wall portion 26 is formed in pairs so as to rise from one end edge in the longitudinal direction D of the bottom wall portion 22 to the other side in the width direction E. The second side wall portion 26 is formed in the shape of a rectangular plate with the longitudinal direction D being the plate thickness direction and extending in the vertical direction F.

[0027] A pair of second side wall portions 26 have elongated openings 26A that penetrate in the thickness direction of the plate.

[0028] As shown in Figure 4, the opening 26A is located at a position that coincides with the winding axis C of the winding body 40 from the viewpoint on the other side in the longitudinal direction D. In other words, the opening 26A is located at a position corresponding to the center of the winding body 40.

[0029] As shown in Figures 2 and 7, a gas exhaust valve 70 is attached to the second side wall portion 26, for example, by adhesive, so as to close the opening 26A. The gas exhaust valve 70 is provided at positions corresponding to both axial ends of the wound body 40 of the case 12. A counterbore hole 26B can be provided in the opening 26A to prevent the gas exhaust valve 70 from protruding outward from the second side wall portion 26.

[0030] The gas discharge valve 70 opens when the internal pressure of the case 12 reaches a predetermined pressure, and discharges the gas generated inside the case 12.

[0031] As shown in Figures 2 and 4, the first case 20 is insert-molded with the current collection terminals 50 as insert parts. The current collection terminals 50 are provided on both ends of the longitudinal direction D of the first case 20.

[0032] Inside the first case 20, there is a covering portion 28 that covers the current collection terminal 50, and a rectangular opening 28A that exposes the current collection terminal 50 to the inside of the first case 20.

[0033] The covering portion 28 is located in the center of the first case 20 in the vertical direction F. The openings 28A are located on the upper and lower sides of the first case 20 in the vertical direction F.

[0034] <Case 2, 30> As shown in Figures 2 and 3, the second case 30 is formed in the shape of a rectangular plate with the width direction E being the plate thickness direction and extending in the longitudinal direction D.

[0035] <Accommodation Space S> As shown in Figure 3, the first case 20 and the second case 30 are joined together, for example, by welding the periphery of the first case 20 and the periphery of the second case 30, thereby forming a housing space S for housing the wound body 40 inside the case 12. The housing space S is formed in a shape in which an elongated hole-like cross section extends in the longitudinal direction D. The housing space S is formed to conform to the outer shape of the wound body 40.

[0036] The inner wall surface 22A forming the housing space S of the first case 20 is in contact with one side (one long side) of the winding body 40 in the width direction E. The inner wall surface 32A forming the housing space S of the second case 30 is in contact with the other side (other long side) of the winding body 40 in the width direction E. The inner wall surfaces 22A and 32A are in contact with both end faces of the winding body 40 in the vertical direction F.

[0037] (Wound body 40) As shown in Figures 2 and 3, the winding body 40 is formed by winding a positive electrode sheet, a negative electrode sheet, and a separator sheet in a stacked state around a winding axis C, so that its cross-section is flattened. The winding body 40 includes a power generator 42, a positive electrode current collector 44, and a negative electrode current collector 46.

[0038] The power generator 42 is formed by laminating a region of a positive electrode sheet coated with positive electrode active material, a region of a negative electrode sheet coated with negative electrode active material, and a separator sheet. The power generator 42 has the function of storing electrical energy from the lithium-ion battery 10.

[0039] The positive electrode current collector 44 is formed by winding a positive electrode sheet without being coated with an active material. The negative electrode current collector 46 is formed by winding a negative electrode sheet without being coated with an active material.

[0040] (Collection terminal 50) As shown in Figure 2, the current collection terminals 50 are provided in pairs at both ends of the case 12 in the longitudinal direction D. A positive current collection terminal, which serves as the current collection terminal 50, is provided at one end of the case 12 in the longitudinal direction D, and a negative current collection terminal, which serves as the current collection terminal 50, is provided at the other end of the case 12 in the longitudinal direction D. The current collection terminals 50 are integrally formed with the first case 20 by insert molding.

[0041] As shown in Figure 5, the current collector terminal 50 is located on one side of the width direction E of the positive electrode current collector 44 and the negative electrode current collector 46. The current collector terminal 50 is made of a conductor (for example, copper). The current collector terminal 50 comprises a base portion 52, a protrusion 54, and an external connection terminal portion 56.

[0042] <Base 52> The base portion 52 is formed in a substantially rectangular plate shape with the width direction E being the plate thickness direction and extending in the vertical direction F. As shown in Figure 7, the base portion 52 is embedded and arranged inside the first case 20. The other side of the base portion 52 in the width direction E is covered by the covering portion 28.

[0043] <Convex part 54> As shown in Figure 5, the protrusions 54 are formed on the upper and lower parts of the base 52 in the vertical direction F, respectively. The protrusions 54 are formed to project from the base 52 to the other side in the width direction E. The protrusions 54 are formed in a rectangular shape when viewed from one side in the width direction E.

[0044] As shown in Figures 5 and 6, the protruding portion 54 has a recessed groove portion 54C that is recessed on one side in the width direction E and extends in the vertical direction F.

[0045] The groove portion 54C has a plurality of projections 54A (five in this embodiment) that protrude to the other side in the width direction E, and a crimping portion 54B that protrudes to the other side in the width direction E.

[0046] The projection 54A is formed in a roughly cylindrical shape with a sharp tip. As shown in Figure 4, the projection 54A is set to a length that does not protrude from the insertion hole 64A of the opposing member 60.

[0047] The crimping portion 54B is positioned above the projection 54A on the upper convex portion 54. The crimping portion 54B is positioned below the projection 54A on the lower convex portion 54.

[0048] The crimping portion 54B is formed in a cylindrical shape that protrudes to the other side in the width direction E. The crimping portion 54B is inserted into the through hole 64B of the opposing member 60 and crimped so that the opposing member 60 does not come off the current collection terminal 50. The crimping portion 54B is configured as a fastening member that fixes the opposing member 60 to the current collection terminal 50.

[0049] <External connection terminal section 56> The external connection terminal portion 56 is formed at the upper end of the current collection terminal 50 in the vertical direction F. The external connection terminal portion 56 is provided exposed so as not to protrude from the first side wall portion 24 of the first case 20.

[0050] (Opponent member 60) As shown in Figure 2, the opposing members 60 are provided in pairs at both ends of the case 12 in the longitudinal direction D.

[0051] As shown in Figure 5, the opposing member 60 is positioned opposite the current collection terminal 50 on the other side in the width direction E of the positive electrode current collection section 44 and the negative electrode current collection section 46. The opposing member 60 is made of a conductor (for example, copper).

[0052] The opposing member 60 comprises a pair of base portions 64, a protruding portion 62, and a connecting portion 63 that connects the base portions 64 and the protruding portion 62.

[0053] <Base section 64> The base portion 64 is formed on the upper and lower sides of the protruding portion 62 in the vertical direction F, respectively. The base portion 64 is positioned opposite the protrusion 54 of the current collection terminal 50. The base portion 64 is formed in a substantially rectangular plate shape with the width direction E being the plate thickness direction and extending in the vertical direction F.

[0054] As shown in Figures 5 and 6, the base portion 64 has a protruding ridge 64C that projects to the other side in the width direction E and extends in the vertical direction F. The protruding ridge 64C is formed to project toward the protrusion 54 of the current collection terminal 50. The protruding ridge 64C is formed to project in the thickness direction of the base portion 64. The protruding ridge 64C is designed so that the recessed groove 54C of the current collection terminal 50 fits into it via the positive current collection portion 44 or the negative current collection portion 46.

[0055] The recessed groove 54C has an insertion hole 64A into which the projection 54A of the current collector terminal 50 is inserted, and a through hole 64B into which the crimping portion 54B of the current collector terminal 50 is inserted.

[0056] The inner diameter of the insertion hole 64A is larger than the outer diameter of the projection 54A. The inner diameter of the through hole 64B is approximately the same as the outer diameter of the crimping portion 54B.

[0057] <Protrusion 62> As shown in Figures 4 and 5, the protrusion 62 is located on the other side of the base portion 64 in the width direction E. The protrusion 62 is positioned opposite the base portion 52 of the current collection terminal 50. The protrusion 62 is formed in a substantially rectangular plate shape with the width direction E being the plate thickness direction and extending in the vertical direction F. A recess 32C is formed in the second case 30 to avoid the protrusion 62.

[0058] <Connection part 63> The connecting portion 63 is formed in a plate shape with the vertical direction F being the plate thickness direction. The connecting portion 63 is formed to connect the end of the base portion 64 and the end of the protruding portion 62.

[0059] <Gas emission space U> As shown in Figure 4, the space enclosed by the covering portion 28, the protruding portion 62, and the connecting portion 63 constitutes a gas discharge space U, which serves as a discharge path for gas generated from the power generator 42 of the winding body 40. The gas discharge space U is located at a position that coincides with the opening 26A and the winding axis C of the winding body 40, when viewed from the other side in the longitudinal direction D. The gas discharge space U is located at a position corresponding to the center of the winding body 40.

[0060] The opposing member 60 is formed by bending to avoid the position corresponding to the gas discharge valve 70. The opposing member 60 is formed by bending away from the winding body so as not to come into contact with the central part of the winding body 40 in the short direction. The current collector terminal 50 is formed by bending to avoid the position corresponding to the gas discharge valve 70. The current collector terminal 50 is formed by bending away from the winding body so as not to come into contact with the central part of the winding body 40 in the short direction.

[0061] [Lithium-ion battery operation 10] In the lithium-ion battery 10 configured as described above, the output of the wound body 40 is taken out from the external connection terminal 56 and used as a power source for electric vehicles, hybrid vehicles, etc.

[0062] [Manufacturing method for lithium-ion battery 10] First, the first case 20 is molded by injection molding with the current collection terminal 50 as an insert. Next, the wound body 40 is installed in the first case 20.

[0063] In this case, the winding body 40 is installed in the first case 20 such that the positive electrode current collector 44 faces the current collector terminal 50 provided on one side of the case 12 in the longitudinal direction D, and the negative electrode current collector 46 faces the current collector terminal 50 provided on the other side of the case 12 in the longitudinal direction D. Furthermore, the winding body 40 is installed in the first case 20 by bringing one side of the winding body 40 in the width direction E (one long side) into contact with the inner wall surface 22A of the first case 20.

[0064] Next, the opposing members 60 are positioned on the other side of the width direction E of the positive electrode current collector 44 and on the other side of the width direction E of the negative electrode current collector 46.

[0065] Next, the opposing member 60 is pressed against the other side in the width direction E, crushing the positive electrode current collector 44 and the negative electrode current collector 46. Then, the projection 54A of the current collector terminal 50 pierces the positive electrode current collector 44 and the negative electrode current collector 46, and the projection 54A is inserted into the insertion hole 64A of the opposing member 60. The crimping portion 54B is also inserted into the through hole 64B of the opposing member 60.

[0066] Next, the crimped portion 54B is crimped to fix the opposing member 60 to the current collection terminal 50. Then, the periphery of the second case 30 and the periphery of the first case 20 are welded together using a welding device.

[0067] Next, the gas discharge valve 70 is attached to the opening 26A using adhesive. The temperature sensing unit 72 is then attached to the opening 24A. The temperature sensing unit 72 can also be attached to the first case 20 by insert molding.

[0068] [Effect] The lithium-ion battery 10 of this embodiment comprises a flat-shaped winding body 40 in which electrode sheets consisting of a positive electrode sheet and a negative electrode sheet are wound, a case 12 for housing the winding body 40, and a gas discharge valve 70 provided in the case 12 at a position corresponding to the axial end of the winding body 40, the gas discharge valve 70 being provided at a position corresponding to the center of the winding body 40 (see Figure 4).

[0069] By providing a gas exhaust valve 70 at a position corresponding to the axial end of the winding body 40 of case 12, the gas exhaust valve 70 is positioned at a location where the gap created when the electrode sheet is wound is opened. Therefore, when gas is generated in the winding body 40 due to thermal runaway, the gas exhaust valve 70 is positioned at a location where the gas is discharged from the winding body 40. As a result, the exhaust gas path can be shortened. Therefore, the size of the secondary battery can be reduced.

[0070] Incidentally, the central part of the wound body 40, where heat dissipation is minimal, becomes hot. Therefore, when thermal runaway occurs, gas tends to be generated from the center of the wound body 40.

[0071] The gas discharge valve 70 is positioned at a location corresponding to the center of the winding body 40, so that the gas generated at the center of the winding body 40 is discharged from the winding body 40. Therefore, the exhaust gas path can be made shorter.

[0072] In the lithium-ion battery 10 of this embodiment, the gas discharge valve 70 is provided at positions corresponding to both axial ends of the wound body 40 of the case 12 (see Figure 2).

[0073] The gas discharge valves 70 are positioned at locations corresponding to both axial ends of the winding body 40 of the case 12, so that gas discharge valves 70 are formed on both axial sides of the winding body 40. Therefore, regardless of the axial direction in which the gas generated in the winding body 40 is discharged, the gas is discharged from the gas discharge valves 70. As a result, the exhaust gas path can be shortened.

[0074] In the lithium-ion battery 10 of this embodiment, the case 12 that houses the wound body 40 is formed to conform to the outer shape of the wound body 40, with a first case 20 that contacts one long side surface of the wound body 40 and a second case 30 that contacts the other long side surface of the wound body 40 (see Figure 3).

[0075] The case 12 housing the winding body 40 is formed to conform to the outer shape of the winding body 40, with a first case 20 that contacts one long side of the winding body 40 and a second case 30 that contacts the other long side of the winding body 40. As a result, the winding body 40 is held in place by the first case 20 and the second case 30. This suppresses misalignment of the gas discharge valve 70 relative to the winding body 40. Consequently, exhaust gas performance can be maintained.

[0076] Furthermore, external vibrations (e.g., vehicle vibrations) prevent the winding body 40 from hitting the case 12. As a result, damage to the winding body 40 can be suppressed.

[0077] In the lithium-ion battery 10 of this embodiment, a current collector terminal 50 is arranged on one long side of the winding body 40, and a counter member 60 is arranged on the other long side of the winding body 40 opposite to the current collector terminal 50, with the current collector terminal 50 and the counter member 60 being arranged so as to avoid the position corresponding to the center of the winding body 40 (see Figure 4).

[0078] The current collector terminal 50 and the opposing member 60 are positioned to avoid the position corresponding to the center of the winding body 40, so that they are not located in the gas discharge passage between the winding body 40 and the gas discharge valve 70. Therefore, the gas discharged from the winding body 40 is discharged from the gas discharge valve 70 without being obstructed by the current collector terminal 50 and the opposing member 60. As a result, a decrease in exhaust gas efficiency can be suppressed.

[0079] The lithium-ion battery 10 of this embodiment includes a current collector terminal 50 positioned on one long side of the winding body 40, and a counter member 60 positioned on the other long side of the winding body 40 opposite the current collector terminal 50. The counter member 60 is formed to bend away from the winding body 40 so as not to come into contact with the central part of the winding body 40 in the short direction (see Figure 4).

[0080] The opposing member 60 is formed by bending away from the winding body 40 so as not to come into contact with the central part of the winding body 40 in the short direction. As a result, the opposing member 60 is not positioned in the gas discharge passage between the winding body 40 and the gas discharge valve 70. Therefore, the gas discharged from the winding body 40 is discharged from the gas discharge valve 70 without being obstructed by the opposing member 60. Consequently, a decrease in exhaust gas efficiency can be suppressed.

[0081] The secondary battery of the present invention has been described above based on the above embodiments. However, the specific configuration is not limited to these embodiments, and changes to the design are permitted as long as they do not deviate from the gist of the invention as described in each claim of the patent claims.

[0082] In the above embodiment, the gas discharge valve 70 is shown to be provided at positions corresponding to both axial ends of the wound body 40 of the case 12. However, the gas discharge valve may be provided on one axial side of the wound body 40 of the case 12.

[0083] In the above embodiment, the gas exhaust valve 70 is shown as being provided separately from the case 12. However, the gas exhaust valve may be formed integrally with the case 12.

[0084] In the above embodiment, the external connection terminal portion 56 is shown as being exposed so as not to protrude from the first side wall portion 24 of the first case 20. However, the external connection terminal portion 56 may be provided so as to protrude from the first side wall portion 24 of the first case 20.

[0085] In the above embodiment, the opposing member 60 was shown to be made of a conductor (for example, copper). However, the material of the opposing member is not limited to this embodiment, and it can also be made of resin, for example.

[0086] In the above embodiment, an example was shown in which a protruding ridge 64C is formed on the opposing member 60 in the thickness direction. However, the protruding ridge may also be formed on the current collection terminal.

[0087] In the above embodiment, an example was shown in which the fastening member that fixes the opposing member 60 to the current collection terminal 50 is a crimping portion 54B. However, the fastening member is not limited to this embodiment and can be, for example, a screw.

[0088] In the above embodiment, an example was shown in which the insertion hole 64A of the opposing member 60 is a through hole. However, the insertion hole of the opposing member can be a bottomed hole that does not go all the way through.

[0089] In the above embodiment, the gas exhaust valve 70 is shown to be located at a position corresponding to the center of the wound body 40 of the first case 20. However, the gas exhaust valve may also be located at other positions in the first case 20. [Explanation of Symbols]

[0090] 10. Lithium-ion battery (an example of a rechargeable battery) 20. Case 1 (An example of a case) 30. Case 2 (An example of a case) 40 Wound body 50 Current collector terminal 60 Opposing members 70 Gas discharge valve

Claims

1. A flattened wound body in which electrode sheets consisting of a positive electrode sheet and a negative electrode sheet are wound, A case for housing the aforementioned coiled body, A gas discharge valve is provided at a position corresponding to the axial end of the winding body of the case, Equipped with, The gas discharge valve is provided at a position corresponding to the center of the coiled body, A secondary battery comprising a case for housing the winding body, the case being formed to conform to the outer shape of the winding body, with a first case in contact with one long side surface of the winding body and a second case in contact with the other long side surface of the winding body.

2. A flat-shaped wound body in which an electrode sheet consisting of a positive electrode sheet and a negative electrode sheet is wound, A case for housing the aforementioned coiled body, A gas discharge valve is provided at a position corresponding to the axial end of the winding body of the case, Equipped with, The gas discharge valve is provided at a position corresponding to the center of the coiled body, A current collection terminal is positioned on one of the long sides of the aforementioned winding body, The other long side of the winding body is provided with an opposing member that is positioned opposite to the current collection terminal, The current collection terminal and the opposing member are arranged to avoid a position corresponding to the center of the wound body in a secondary battery.

3. A flat-shaped wound body in which an electrode sheet consisting of a positive electrode sheet and a negative electrode sheet is wound, A case for housing the aforementioned coiled body, A gas discharge valve is provided at a position corresponding to the axial end of the winding body of the case, Equipped with, The gas discharge valve is provided at a position corresponding to the center of the coiled body, A current collection terminal is positioned on one of the long sides of the aforementioned winding body, The other long side of the winding body is provided with an opposing member that is positioned opposite to the current collection terminal, The opposing member is formed to bend away from the winding body so as not to come into contact with the central part of the winding body in the short direction, in a secondary battery.

4. The gas discharge valve is provided at positions corresponding to both axial ends of the winding body of the case. A secondary battery according to any one of claims 1 to 3.

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