JP2016225014A - Cylindrical secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the vibration of a wound electrode group in a sheet outer sheath.SOLUTION: In a cylindrical secondary battery having a wound electrode group on which an electrode and a separator are wound around a shaft core, a sealed space for housing the wound electrode group is formed of: a first lid member fixed on one end of the shaft core; a second lid member fixed on the other end of the shaft core; and a sheet outer sheath fixed to the first and second lid members and disposed in a manner to cover the outer periphery of the wound electrode group. The sheet outer sheath is of a laminate structure of resin laminated with a metal foil.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cylindrical secondary battery.

  A cylindrical wound electrode group (a wound electrode body) in which a sheet-like positive electrode and a sheet-like negative electrode are wound in a spiral shape through a separator, and a non-aqueous electrolyte solution is a sheet outer body ( A lithium ion secondary battery housed in a laminate film outer package is known (see Patent Document 1).

  In the secondary battery of Patent Document 1, a three-layer structure comprising an exterior resin layer made of nylon film or the like, a metal layer made of aluminum film or the like, and a heat-weldable resin layer made of modified polyolefin film or the like The exterior body comprised by the laminate film of this is used. The secondary battery is sealed by welding a laminate film at the welding and sealing portions at both ends of the sheet outer package.

JP 2008-171579 A

  In the secondary battery described in Patent Document 1, the external terminal is connected to the sheet-like electrode constituting the wound electrode group directly or via a lead body or the like inside the sheet exterior body. The group is held by external terminals that are taken out from both ends of the sheet outer package. However, in such a configuration, when the vibration acts on the secondary battery, the wound electrode group may vibrate within the sheet outer package.

  The cylindrical secondary battery according to claim 1 is a cylindrical secondary battery having a wound electrode group in which an electrode and a separator are wound around an axial core, the first lid member being fixed to one end of the axial core. And a second lid member fixed to the other end of the shaft core, and a sheet exterior body fixed to the first lid member and the second lid member and arranged to cover the outer periphery of the wound electrode group, A sealed space for accommodating the rotating electrode group is formed, and the sheet outer package has a laminated structure in which a resin is laminated on a metal foil.

  According to the present invention, it is possible to suppress vibration of the wound electrode group in the sheet outer package.

The schematic diagram which shows the external appearance of the secondary battery which concerns on this Embodiment. The cross-sectional schematic diagram of the secondary battery which concerns on this Embodiment. The exploded schematic diagram which shows the structure of an electric power generation unit. The perspective view of the state which cut a part of winding electrode group. The cross-sectional schematic diagram which shows the structure of an upper cover unit. The cross-sectional schematic diagram which shows the structure of a lower cover unit. The flowchart which shows the method of manufacturing a secondary battery. The schematic diagram explaining the position holding a secondary battery.

  Hereinafter, an embodiment in which the present invention is applied to a cylindrical lithium ion secondary battery (hereinafter simply referred to as a secondary battery) will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing the appearance of the secondary battery according to the present embodiment, and FIG. 2 is a schematic sectional view of the secondary battery according to the present embodiment. The secondary battery 10 according to the present embodiment is cylindrical, and has a positive external terminal provided at one end in the central axis direction (the vertical direction in the drawing) of the secondary battery 10 and a negative external terminal provided at the other end. Yes.

  As shown in FIG. 2, the secondary battery 10 includes a cylindrical sheet exterior body 200 having openings at both ends, and a power generation unit 100 disposed in the sheet exterior body 200. Hereinafter, for convenience of explanation, the vertical direction is defined as shown, and the side on which the upper lid unit 130 including the positive external terminal 133 is disposed is the upper side of the secondary battery 10 and the lower lid unit 140 including the negative external terminal 145 is provided. The arrangement side will be described as the lower side of the secondary battery 10.

  FIG. 3 is an exploded schematic view showing the configuration of the power generation unit 100. As shown in FIG. 3, the power generation unit 100 includes a wound electrode group 110 that is a charge / discharge element, an upper lid unit 130 that is fixed to the upper end of the shaft core 115 of the wound electrode group 110, and the wound electrode group 110. And a lower lid unit 140 fixed to the lower end of the shaft core 115.

  As shown in FIG. 2, the upper end opening of the sheet exterior body 200 is closed by the upper lid unit 130, and the lower end opening of the sheet exterior body 200 is closed by the lower lid unit 140. That is, the sheet exterior body 200, the upper lid unit 130, and the lower lid unit 140 are configured as a sealed container for forming a cylindrical sealed space, and a nonaqueous electrolytic solution (hereinafter simply referred to as electrolysis) is formed in the sealed container. (Referred to as liquid 105). An example of the electrolytic solution 105 is a solution in which a lithium salt is dissolved in a carbonate-based solvent.

  As shown in FIG. 1, the sheet outer package 200 is a portion in which a laminate film obtained by laminating a stainless steel metal foil and an insulating resin sheet is rolled into a cylindrical shape, and then the end portions of the laminate film are overlapped. A certain overlapping portion 201 is formed by laser welding. The laminated film constituting the sheet outer package 200 has a thickness of about 50 to 200 μm, for example, and has a three-layer structure in which metal foil is provided on both surfaces of the resin sheet via an adhesive layer, or an adhesive layer on one surface of the resin sheet. A laminated film having a two-layer structure in which a metal foil is provided through the film can be employed. In addition, it is good also as a multilayered structure of four or more layers.

  The laminate film that is the material of the sheet outer package 200 has a structure in which a resin sheet thicker than the thickness of the metal foil is laminated on the metal foil, is a flexible structure mainly composed of the resin sheet, and has good moldability. The cylindrical sheet outer package 200 has an upper end fixed to an outer peripheral side surface of an outer ring 144 in an upper lid unit 130 to be described later by laser welding, and an outer ring 148 in a lower lid unit 140 to be described later by laser welding. It is fixed to the outer peripheral side surface.

  FIG. 4 is a perspective view of a state where a part of the wound electrode group 110 is cut. As shown in FIG. 4, the wound electrode group 110 includes a shaft core 115 extending in the vertical direction, and a positive electrode 111, a negative electrode 112, a first separator 113, and a second separator 114 around the shaft core 115. It has a wound structure.

  The shaft core 115 is made of, for example, an insulating resin material such as polypropylene (PP) and has an elongated cylindrical shape having a hollow portion 115c. The shaft core 115 is provided with a fitting portion 151 at each of both end portions in a direction parallel to the winding central axis of the wound electrode group 110 (hereinafter referred to as an axial direction). The shaft core 115 is provided with a wound portion 150 between the fitting portions 151 at both ends where the positive electrode 111 and the negative electrode 112 are wound.

  A first separator 113, a negative electrode 112, a second separator 114, and a positive electrode 111 are stacked and wound on the winding portion 150 of the shaft 115. The first separator 113 and the second separator 114 are wound several times (one turn in FIG. 4) inside the innermost negative electrode 112. The first separator 113 and the second separator 114 are each formed of an insulating porous material such as a polyethylene porous film having a thickness of 40 μm.

  In the innermost periphery (axial core 115 side), the negative electrode 112 is wound more on the inner peripheral side than the positive electrode 111, and the start of the negative electrode 112 extends in the circumferential direction from the start of the positive electrode 111. Has been. In the outermost periphery (sheet outer package 200 side), the negative electrode 112 is wound more outward than the positive electrode 111, and the end of the negative electrode 112 is extended in the circumferential direction from the end of the positive electrode 111. Yes. A first separator 113 is wound around the outer periphery of the outermost negative electrode 112. The terminal end of the outermost first separator 113 is stopped with an adhesive tape 119 (see FIG. 3). In addition, after the 1st separator 113 and the 2nd separator 114 are wound several times in the outermost periphery, it may be stopped with the adhesive tape 119.

  The positive electrode 111 has an elongated positive electrode metal foil 111a formed of an aluminum foil, and a positive electrode mixture layer 111b in which a positive electrode mixture is applied to both surfaces of the positive electrode metal foil 111a. The upper side edge extending in the longitudinal direction (that is, the winding direction) of the positive electrode metal foil 111a is a positive electrode foil exposed portion 111c where the positive electrode mixture is not applied and the positive electrode metal foil 111a is exposed. A large number of positive electrode current collecting tabs (hereinafter referred to as positive electrode tabs 116) projecting upward along the axial direction are integrally formed at regular intervals along the longitudinal direction of the positive electrode metal foil 111a. Is formed.

  The positive electrode mixture includes a positive electrode active material, a positive electrode conductive material, and a positive electrode binder. Examples of the positive electrode active material include lithium oxides such as cobalt, manganese, and nickel. Examples of the positive electrode binder include polyvinylidene fluoride (PVDF) and fluororubber.

  Examples of the method for applying the positive electrode mixture to the positive electrode metal foil 111a include a roll coating method and a slit die coating method. A slurry obtained by kneading a dispersion solution in a positive electrode mixture is uniformly applied to both surfaces of an aluminum foil having a thickness of 20 μm, dried, pressed, and cut. An example of the coating thickness of the positive electrode mixture is about 40 μm on one side. When cutting the positive electrode metal foil 111a, the positive electrode tab 116 is integrally formed. The lengths of all the positive electrode tabs 116 are substantially the same.

  The negative electrode 112 has a long negative electrode metal foil 112a formed of a copper foil, and a negative electrode mixture layer 112b in which a negative electrode mixture is applied to both surfaces of the negative electrode metal foil 112a. The lower side edge extending in the longitudinal direction (that is, the winding direction) of the negative electrode metal foil 112a is a negative electrode foil exposed portion 112c where the negative electrode mixture is not applied and the copper foil is exposed. A large number of negative electrode current collecting tabs (hereinafter referred to as negative electrode tabs 117) projecting downward along the axial direction are integrally formed at equal intervals along the longitudinal direction of the negative electrode metal foil 112a. Is formed.

  The negative electrode mixture includes a negative electrode active material, a negative electrode binder, and a thickener. An example of the negative electrode active material is graphite carbon. Examples of the method for applying the negative electrode mixture to the negative electrode metal foil 112a include a roll coating method and a slit die coating method. A slurry obtained by kneading a dispersion solvent in a negative electrode mixture is uniformly applied to both sides of a rolled copper foil having a thickness of 10 μm, dried, and then cut. An example of the coating thickness of the negative electrode mixture is about 40 μm on one side. When the negative electrode metal foil 112a is cut by pressing, the negative electrode tab 117 is integrally formed. All the negative electrode tabs 117 have substantially the same length.

  The axial lengths of the first separator 113 and the second separator 114 are larger than the axial length of the negative electrode mixture layer 112b of the negative electrode 112. The axial length of the negative electrode mixture layer 112 b of the negative electrode 112 is larger than the axial length of the positive electrode mixture layer 111 b of the positive electrode 111. The length of the negative electrode mixture layer 112b in the axial direction and the length in the winding direction are larger than the length of the positive electrode mixture layer 111b in the axial direction and the length in the winding direction, so that the entire region of the positive electrode mixture layer 111b Is covered with the negative electrode mixture layer 112b.

  In the case of a lithium ion secondary battery, lithium, which is a positive electrode active material, is ionized, penetrates the separator, and is occluded by the negative electrode active material. In this case, if the negative electrode active material is not formed on the negative electrode side and the negative electrode metal foil 112a is exposed, lithium is deposited on the negative electrode metal foil 112a, causing an internal short circuit. As described above, by covering the entire region of the positive electrode mixture layer 111b with the negative electrode mixture layer 112b, it is possible to prevent such an internal short circuit due to lithium deposition.

  A fitting portion 151 provided at the upper end of the shaft core 115 is fixed to a positive electrode current collecting ring 127 (see FIG. 5) described later, and a fitting portion 151 provided at the lower end of the shaft core 115 is connected to a negative electrode collector described later. It is fixed to the electric ring 121 (see FIG. 6). In the present embodiment, the fitting portions 151 provided at the upper end and the lower end of the shaft core 115 have the same shape.

  The fitting portion 151 includes a flange portion 153 formed at the tip, and an annular fitting groove 152 provided on the outer peripheral surface between the flange portion 153 and the winding portion 150. The flange portion 153 has a tapered shape in which the diameter increases as the distal end portion moves from the distal end side toward the fitting groove 152. The outer diameter of the fitting groove 152 is smaller than the outer diameter of the wound portion 150 and smaller than the maximum value of the outer diameter of the flange portion 153.

  FIG. 5 is a schematic cross-sectional view showing the configuration of the upper lid unit 130, and is an enlarged view of a part of FIG. As shown in FIG. 5, when the flange portion 153 of the fitting portion 151 at the upper end of the shaft core 115 is press-fitted so as to penetrate the inside of the fitting cylindrical portion 127 b of the positive electrode current collecting ring 127 described later, the fitting groove 152 is fitted into the fitting cylindrical portion 127 b of the positive electrode current collecting ring 127. The fitting cylinder portion 127b is sandwiched between the flange portion 153 and the winding portion 150, and movement in the vertical direction is restricted. As a result, the shaft core 115 is prevented from coming off and coming off from the positive electrode current collecting ring 127, and the positive electrode current collecting ring 127 is fixed to the fitting portion 151 at the upper end of the shaft core 115. In addition, since the collar part 153 is a taper taper shape, the insertion property with respect to the fitting cylinder part 127b of the positive electrode current collection ring 127 is good. As shown in FIG. 4, the collar portion 153 is provided with a notch 154 cut into a concave cross section from the tip toward the winding portion 150, and has a bifurcated shape. For this reason, when the flange part 153 is inserted into the fitting cylinder part 127b, portions extending in the axial direction from both ends of the notch 154 are bent inward in the axial direction.

  As shown in FIG. 5, a positive electrode lead member 139 (see FIG. 3) to be described later is disposed in a notch 154 provided in the fitting portion 151 at the upper end of the shaft core 115. That is, the notch 154 of the fitting portion 151 at the upper end of the shaft core 115 also has a function of avoiding interference between the positive electrode lead member 139 and the shaft core 115.

  6 is a schematic cross-sectional view showing the configuration of the lower lid unit 140, and is an enlarged view of a part of FIG. As shown in FIG. 6, when the flange portion 153 of the fitting portion 151 at the lower end of the shaft core 115 is press-fitted so as to penetrate the inside of the fitting cylindrical portion 121 b of the negative electrode current collecting ring 121 described later, the fitting groove 152 is fitted into the fitting cylinder 121 b of the negative electrode current collecting ring 121. The fitting cylinder portion 121b is sandwiched between the flange portion 153 and the winding portion 150, and movement in the vertical direction is restricted. Accordingly, the shaft core 115 is prevented from coming off and coming off from the negative electrode current collecting ring 121, and the negative electrode current collecting ring 121 is fixed to the fitting portion 151 at the lower end of the shaft core 115. In addition, since the collar part 153 is a taper taper shape, the insertion property with respect to the fitting cylinder part 121b of the negative electrode current collection ring 121 is good. As shown in FIG. 4, the collar portion 153 is provided with a notch 154 cut into a concave cross section from the tip toward the winding portion 150, and has a bifurcated shape. For this reason, when the flange part 153 is inserted into the fitting cylinder part 127b, portions extending in the axial direction from both ends of the notch 154 are bent inward in the axial direction.

  As shown in FIG. 5, the upper lid unit 130 includes a positive current collecting ring 127 fitted and fixed to the upper end of the shaft core 115, a ring-shaped insulating plate 134, and a circular opening 134 a of the insulating plate 134. The connection plate 135 fitted in (see FIG. 3), the positive electrode lead member 139 fixed to each of the positive electrode current collecting ring 127 and the connection plate 135 by welding, the diaphragm 137 welded to the connection plate 135, and the diaphragm 137 A positive external terminal 133 fixed by caulking and welding, a gasket 143, and an exterior ring 144 are included.

  The positive electrode current collecting ring 127 is made of, for example, an aluminum-based metal. As shown in FIGS. 3 and 5, the positive electrode current collecting ring 127 includes a disk-shaped base 127 a and a fitting cylinder 127 b (not shown in FIG. 3) that protrudes downward at the center of the base 127 a. The upper cylindrical portion 127c that protrudes upward at the outer peripheral edge of the base portion 127a, and the flange portion 127d that extends outward in the radial direction of the wound electrode group 110 from the outer peripheral edge of the upper cylindrical portion 127c. As described above, as shown in FIG. 5, the positive electrode current collecting ring 127 is formed by pressing the fitting cylinder portion 127b into the fitting groove 152 formed in the fitting portion 151 at the upper end of the shaft core 115, thereby It is fixed and supported at the upper end of the core 115.

  As shown in FIG. 5, a large number of positive electrode tabs 116 and a pressing member 128 provided on the positive electrode 111 are welded to the outer periphery of the upper cylindrical portion 127 c of the positive electrode current collecting ring 127. As a welding method, first, a large number of positive electrode tabs 116 are brought into close contact with the outer periphery of the upper cylindrical portion 127 c of the positive electrode current collecting ring 127. Next, the presser member 128 is wound around the outer periphery of the positive electrode tab 116 in a ring shape and temporarily fixed. In this state, ultrasonic welding is performed, and the positive electrode tab 116 and the presser member 128 are joined to the upper cylindrical portion 127c.

  As shown in FIG. 3, an opening 127 e is formed in the base 127 a of the positive electrode current collecting ring 127. The opening 127e serves as a passage through which gas generated inside the battery passes when a diaphragm 137 described later is cleaved. One end of a positive electrode lead member 139 is joined to the upper surface of the base 127a of the positive electrode current collecting ring 127 by welding. The positive electrode lead member 139 is a flexible conductive member configured by laminating a plurality of aluminum foils.

  The insulating plate 134 is made of an insulating resin material and has an opening 134a and a cylindrical portion 134b protruding downward. As shown in FIG. 5, the cylindrical portion 134 b of the insulating plate 134 is fitted inside the upper cylindrical portion 127 c of the positive electrode current collecting ring 127, and the connection plate 135 is fitted into the opening 134 a of the insulating plate 134. ing. The other end of the positive electrode lead member 139 is joined to the lower surface of the connection plate 135 by welding.

  The connection plate 135 is formed of an aluminum-based metal, and has a substantially dish shape in which almost the entire portion excluding the central portion has a uniform thickness and the central side is bent to a slightly lower position. At the center of the connection plate 135, a thin-walled dome-shaped protrusion 135a is formed. As shown in FIG. 3, a plurality of openings 135 b are formed around the protrusions 135 a in the connection plate 135. The opening 135b serves as a passage through which gas generated inside the battery passes when a diaphragm 137 described later is cleaved.

  As shown in FIG. 5, the protrusion 135 a of the connection plate 135 is joined to the bottom surface of the central portion of the diaphragm 137 by resistance welding or friction stir welding. When the internal pressure of the battery rises, the central portion of the diaphragm 137 is deformed so as to expand upward, that is, the diaphragm 137 warps upward. When the internal pressure of the battery reaches a predetermined current cutoff pressure, the connection between the projection 135a and the diaphragm 137 is cut off due to the deformation of the diaphragm 137, and the conduction between the positive external terminal 133 and the positive current collecting ring 127 is cut off. Is done. That is, the connection plate 135 and the diaphragm 137 constitute a current interrupt mechanism that interrupts current.

  Diaphragm 137 is formed of an aluminum-based metal. As shown in FIGS. 3 and 5, the diaphragm 137 has a circular cut 137 a centering on the center of the diaphragm 137. The notch 137a is formed by crushing the upper surface side into a V shape by pressing and thinning the remaining part.

  The diaphragm 137 is provided for ensuring the safety of the battery, and when the internal pressure of the battery rises and reaches a predetermined gas discharge pressure, the diaphragm 137 has a function of cleaving at the cut 137a and releasing the internal gas. A gas discharge mechanism is configured. The above-described current cutoff pressure is set to a pressure lower than the gas discharge pressure. When the internal pressure of the battery increases, the current cutoff mechanism operates as the first stage, and the gas discharge mechanism operates as the second stage. .

  As shown in FIG. 5, the diaphragm 137 is caulked and fixed at the peripheral edge of the positive external terminal 133 at the peripheral edge, and is integrated with the positive external terminal 133. As shown in FIG. 3, the diaphragm 137 initially has a side wall 137 b that rises upward at the peripheral edge. The positive electrode external terminal 133 is accommodated in the side wall 137b, and the side wall 137b is bent and fixed to the upper surface side of the positive electrode external terminal 133 by caulking, whereby the diaphragm 137 is fixed to the positive electrode external terminal 133.

  The positive external terminal 133 is made of iron such as carbon steel, and nickel plating is applied to both front and back surfaces. As shown in FIGS. 3 and 5, the positive external terminal 133 includes an annular peripheral portion 133a that contacts the diaphragm 137, a cylindrical portion that protrudes upward from the inner peripheral edge of the peripheral portion 133a, and an upper opening of the cylindrical portion. A hat type having a terminal portion 133b composed of a disc portion provided so as to close the cover. An opening 133c is formed in the disk portion of the terminal portion 133b. The opening 133c serves as a passage through which gas generated inside the battery passes when the diaphragm 137 is cleaved. The positive external terminal 133 is electrically connected to the positive current collecting ring 127 and functions as one power output terminal of the secondary battery 10.

  As shown in FIG. 5, the gasket 143 is provided so as to cover a caulking fixing portion that is a connection portion between the diaphragm 137 and the positive electrode external terminal 133 and an outer peripheral edge portion of the flange portion 127 d of the positive electrode current collecting ring 127. .

  As shown in FIG. 5, the caulking fixing portion between the positive electrode external terminal 133 and the diaphragm 137, the insulating plate 134, and the flange portion 127 d of the positive electrode current collecting ring 127 are laminated and the exterior is interposed through the gasket 143. The ring 144 is sandwiched between the inner contact portion 144a and the outer contact portion 144c so as to be integrated.

  The gasket 143 is made of, for example, an insulating rubber such as a fluorine resin. As shown in FIG. 3, the gasket 143 is initially provided with an outer peripheral wall portion 143b that rises substantially vertically from the outer peripheral edge of the annular base portion 143a upward.

  The exterior ring 144 is made of a stainless material. The outer ring 144 is initially provided with an outer peripheral wall portion 144b that rises substantially vertically upward from the outer peripheral edge of the annular inner contact portion 144a.

  By pressing or the like, the outer peripheral wall portion 144b of the outer ring 144 and the outer peripheral wall portion 143b of the gasket 143 are bent, that is, caulking is performed. Thereby, as shown in FIG. 5, after the front end side of the outer peripheral wall portion 144b is bent, it becomes an outer contact portion 144c. By the caulking process, the positive electrode external terminal 133, the diaphragm 137, the insulating plate 134, and the positive electrode current collecting ring 127 are fixed by the exterior ring 144 through the gasket 143.

  As shown in FIGS. 3 and 6, the lower lid unit 140 includes a negative current collector ring 121 fitted and fixed to the lower end of the shaft core 115, and a negative electrode external terminal 145 fixed to the negative current collector ring 121 by welding. The gasket 147 and the exterior ring 148 are configured.

  The negative electrode current collecting ring 121 is made of, for example, a copper-based metal. The negative electrode current collecting ring 121 includes a disk-shaped base 121a, a fitting cylinder 121b protruding upward at the center of the base 121a, and a lower cylinder 121c protruding downward at the outer peripheral edge of the base 121a. And a flange 121d extending from the outer peripheral edge of the lower cylindrical portion 121c toward the radially outer side of the wound electrode group 110. As described above, the negative electrode current collector ring 121 is formed by inserting the fitting cylinder portion 121b into the fitting groove 152 formed in the fitting portion 151 at the lower end of the shaft core 115 as shown in FIG. It is fixed and supported at the lower end of the core 115.

  As shown in FIG. 3, an opening for allowing the electrolyte solution 105 (see FIG. 2) injected into the hollow portion 115 c of the shaft core 115 to penetrate into the wound electrode group 110 is formed in the base portion 121 a of the negative electrode current collecting ring 121. 121e is formed. The opening 121e also serves as a passage through which a gas generated inside the battery passes when a negative electrode external terminal 145 described later is cleaved.

  As shown in FIG. 6, a large number of negative electrode tabs 117 and a pressing member 122 provided on the negative electrode 112 are welded to the outer periphery of the lower cylindrical portion 121 c of the negative electrode current collecting ring 121. As a welding method, first, a large number of negative electrode tabs 117 are brought into close contact with the outer periphery of the lower cylindrical portion 121 c of the negative electrode current collecting ring 121. Next, the holding member 122 is wound around the outer periphery of the negative electrode tab 117 in a ring shape and temporarily fixed. In this state, ultrasonic welding is performed, and the negative electrode tab 117 and the holding member 122 are joined to the lower cylindrical portion 121c. The flange 121d of the negative electrode current collecting ring 121 is joined to the negative electrode external terminal 145 by resistance welding, laser welding, or the like.

  The negative external terminal 145 is made of iron such as carbon steel, and nickel plating is applied to both front and back surfaces. As shown in FIGS. 3 and 6, the negative electrode external terminal 145 has a disk shape, and a concave portion 145 b that is recessed toward the inside of the container is provided at the center. A liquid injection hole 145c for injecting the electrolytic solution 105 is formed at the bottom of the recess 145b. The negative external terminal 145 is electrically connected to the negative current collecting ring 121 and functions as the other power output terminal of the secondary battery 10.

  As shown in FIG. 6, the injection hole 145 c is sealed with a sealing plug 146 after the electrolyte solution 105 is injected. The sealing plug 146 includes a base 146a that contacts the bottom surface of the recess 145b, and a protrusion 146b that protrudes from the base 146a and is fitted into the liquid injection hole 145c. Since the sealing plug 146 is laser-welded in a state where the base portion 146a is in close contact with the bottom surface of the concave portion 145b, it is possible to prevent spatter from entering the container.

  The negative external terminal 145 has a circular cut 145 a centering on the center of the negative external terminal 145. The notch 145a is formed by crushing the lower surface side into a V shape by pressing and thinning the remaining part. The negative electrode external terminal 145 constitutes a gas discharge mechanism having a function of cleaving at the cut 145a and releasing the internal gas when the internal pressure of the battery rises and reaches a predetermined gas discharge pressure. The gas discharge pressure for cleaving the diaphragm 137 and the gas discharge pressure for cleaving the negative electrode external terminal 145 may be set to the same value or different values. At least the gas discharge pressure set for each of the diaphragm 137 and the negative electrode external terminal 145 is set to a pressure higher than the above-described current cutoff pressure.

  The negative electrode external terminal 145 and the flange portion 121d of the negative electrode current collecting ring 121 are sandwiched between the outer contact portion 148a and the inner contact portion 148c of the outer ring 148 via the gasket 147, and are integrated. It has become.

  The gasket 147 is made of, for example, an insulating rubber such as a fluorine resin. As shown in FIG. 3, the gasket 147 is initially provided with an outer peripheral wall portion 147b that rises substantially vertically from the outer peripheral edge of the annular base portion 147a upward.

  The exterior ring 148 is formed of a stainless material. The outer ring 148 is initially provided with an outer peripheral wall portion 148b that rises substantially vertically upward from the outer peripheral edge of the annular outer contact portion 148a.

  The outer peripheral wall portion 147b of the gasket 147 is bent together with the outer peripheral wall portion 148b of the exterior ring 148 by pressing or the like, that is, caulking is performed. Thereby, as shown in FIG. 6, after the front end side of the outer peripheral wall part 148b is bent, it becomes an inner contact part 148c. By the caulking process, the negative external terminal 145 and the negative current collecting ring 121 are fixed by the exterior ring 148 via the gasket 147.

  FIG. 7 is a flowchart illustrating a method for manufacturing a secondary battery. With reference to FIG. 7, an example of the manufacturing method of a secondary battery is demonstrated. As shown in FIG. 7, the secondary battery 10 includes a sheet outer package manufacturing process S100, a wound electrode group manufacturing process S110, an upper lid unit manufacturing process S120, a lower lid unit manufacturing process S130, an assembly process S140, and a sheet outer package- The outer ring welding process S150, the liquid injection process S160, and the liquid injection hole sealing process S170 are performed.

-Sheet exterior body manufacturing process-
In the sheet exterior body manufacturing step S100, a rectangular laminate film in which a resin sheet is laminated on a metal foil is prepared. The length of the laminate film in the longitudinal direction is a length obtained by adding the length of the overlapping portion 201 to the outer peripheral length of the secondary battery 10. The length of the laminate film in the short direction is substantially the same as the height of the secondary battery 10.

  The laminate film is rounded into a cylindrical shape using an elliptical columnar jig (not shown) and the like, and the overlapping portion is obtained by bringing the inner peripheral surface of one end of the laminate film into contact with the outer peripheral surface of the other end. 201 is formed and laser welding is performed. In laser welding, the jig is arranged on the inner peripheral side of the overlapping portion 201 shown in FIG. 1, and laser is irradiated from the outer peripheral side of the overlapping portion 201, and laser is emitted along the longitudinal direction of the overlapping portion 201, that is, the axial direction. Scan.

  The welded portion 210 formed in the overlapping portion 201 shown in FIG. 1 can improve the strength as the welding area increases. In the present embodiment, the laser spot diameter is adjusted so that the welding width is 0.5 mm or more. As a result, when the internal pressure of the battery rises, the welded part 210 is damaged due to the shearing force acting on the welded part 210 of the overlapping part 201 before the current interruption mechanism and the gas discharge mechanism are activated, and the laminate film It can prevent that both ends are divided.

  After performing laser welding in the overlapping portion 201 in the axial direction, as shown in FIG. 1, each of the upper end portion and the lower end portion of the overlapping portion 201 is further laser-welded to form the reinforcing welded portion 230. Thereby, the sheet exterior body 200 is produced.

-Winding electrode group production process-
In the wound electrode group manufacturing step S110 shown in FIG. 7, the positive electrode 111 and the negative electrode 112 are wound around the wound portion 150 of the shaft core 115 via the first separator 113 and the second separator 114. A rotating electrode group 110 is produced.

-Upper lid unit manufacturing process-
The upper lid unit manufacturing step S120 includes steps S121 to S125. In step S121, the positive electrode lead member 139 is welded to the positive electrode current collecting ring 127, and the process proceeds to the next step. In addition, the positive electrode lead member 139 can arrange | position the center part to the notch 154 in the fitting part 151 of the axial center 115, and can contact both ends to the positive electrode current collection ring 127 (refer FIG. 5). If the notch 154 is not provided, the positive electrode lead member 139 may be disposed on the fitting portion 151, and the positive electrode lead member 139 may contact unintentionally at the center portion of the connection plate 135.

  The width of the positive electrode lead member 139 is preferably the same as or slightly smaller than the width of the notch 154. Note that if the width of the positive electrode lead member 139 is reduced, the cross-sectional area may be reduced and the electrical resistance may be increased. For this reason, when reducing the width of the positive electrode lead member 139, it is preferable to increase the thickness of the positive electrode lead member 139 by that amount to ensure a necessary cross-sectional area.

  In step S122, the positive electrode current collecting ring 127 is fitted and fixed to the fitting portion 151 at the upper end of the shaft core 115, and the process proceeds to the next step S123. In step S123, a horn is arranged on the outer peripheral side of the positive electrode current collecting ring 127, an anvil (receiving part) is arranged on the inner peripheral side of the positive electrode current collecting ring 127, and the positive electrode current collecting ring 127 and the positive electrode of the wound electrode group 110 are arranged. The tab 116 is joined by ultrasonic welding, and the process proceeds to the next step S124. In addition, in this process S123, since it is necessary to ensure the arrangement space of a horn and an anvil, this process S123 needs to be performed before process S124 and process S125 mentioned later.

  In step S124, the connection plate 135 and the positive electrode lead member 139 are welded, and the process proceeds to the next step S125. In step S <b> 125, the outer ring 144 is caulked together with the gasket 143, and the upper lid unit 130 is manufactured by integrating the positive electrode external terminal 133, the diaphragm 137, the insulating plate 134, and the positive electrode current collecting ring 127 with the outer ring 144.

-Lower lid unit manufacturing process-
The lower lid unit manufacturing step S130 includes steps S132 to S135. In step S132, the negative electrode current collecting ring 121 is fitted and fixed to the fitting portion 151 at the lower end of the shaft core 115, and the process proceeds to the next step S133. In step S133, a horn is disposed on the outer peripheral side of the negative electrode current collecting ring 121, an anvil (receiving part) is disposed on the inner peripheral side of the negative electrode current collecting ring 121, and the negative electrode current collecting ring 121 and the negative electrode of the wound electrode group 110 are disposed. The tab 117 is joined by ultrasonic welding, and the process proceeds to the next step S135. In addition, in this process S133, since it is necessary to ensure the arrangement space of a horn and an anvil, this process S133 needs to be performed before process S135 mentioned later.

  In step S135, the outer ring 148 is caulked together with the gasket 147, and the negative electrode external terminal 145 and the negative electrode current collecting ring 121 are integrated with the outer ring 144 to produce the lower lid unit 140.

  When the upper lid unit 130 and the lower lid unit 140 are produced, the power generation unit 100 in which the upper lid unit 130 and the lower lid unit 140 are fixed to the shaft core 115 of the wound electrode group 110 is produced. Note that either the upper lid unit 130 or the lower lid unit 140 may be manufactured first. When the power generation unit 100 is manufactured, the process proceeds to the next step S140.

-Assembly process-
In the assembly step S140, the power generation unit 100 is inserted inside the cylindrical sheet outer package 200 produced in the step S100, and positioning for welding in the next step S150 is performed. Thereby, the sheet exterior body 200 is disposed so as to cover the outer periphery of the wound electrode group 110. Since the sheet exterior body 200 has flexibility and is easily bent, the power generation unit 100 is inserted in a state where the cylindrical shape is maintained by a jig (not shown) or the like.

-Sheet outer body-Exterior ring welding process-
In the sheet exterior body-exterior ring welding step S150, as shown in FIG. 1, laser welding is performed at the overlapping portion between the outer peripheral side surface of the exterior ring 144 and the upper end portion of the sheet exterior body 200 to form a welded portion 220a. Similarly, laser welding is performed at the overlapping portion between the outer peripheral side surface of the exterior ring 148 (see FIG. 6) and the lower end portion of the sheet exterior body 200 to form a welded portion 220b. As a result, a sealed container is formed in which the upper lid unit 130, the lower lid unit 140, and the sheet exterior body 200 serve as a sealed space in which the wound electrode group 110 is accommodated.

  In the present embodiment, since the overlapping portion 201 is formed in which both ends of the laminate film that is the material of the sheet outer package 200 overlap, the gap between the laminate film and the outer rings 144 and 148 in the vicinity of the overlapping portion 201 is formed. A slight gap is formed. However, in the present embodiment, since the reinforcement welding portion 230 is formed in advance, it is possible to ensure the penetration at the overlapping portion 201 and to seal the inside of the battery. Laser welding starts at the overlapping portion 201, and after wrapping, overlaps at the overlapping portion 201 and ends. As a result, a sufficient amount of penetration at the overlapping portion 201 can be ensured, and stable welding can be achieved.

-Injection process-
In the liquid injection step S160 shown in FIG. 7, the upper lid unit 130 is disposed on the lower side, and the lower lid unit 140 is disposed on the upper side. Is attached to the liquid injection hole 145c. The inside of the container is depressurized, and then a predetermined amount of electrolytic solution 105 is injected. When the injection of the electrolytic solution 105 is completed, the process proceeds to the next step S170.

-Injection hole sealing process-
In the liquid injection hole sealing step S170, the liquid injection hole 145c is sealed with the sealing plug 146. The sealing plug 146 is fixed to the negative electrode external terminal 145 by laser welding. Thereby, the secondary battery 10 is completed.

  FIG. 8 is a schematic diagram for explaining a position where the secondary battery 10 is held. In the drawing, the support portion S is indicated by a white triangle (Δ). The secondary battery 10 can be supported as follows, for example. In FIG. 8A, the support portions S are disposed at both axial ends of the sheet exterior body 200 that is in contact with the exterior rings 144 and 148, and the exterior rings 144 and 148 are attached from the radially outer side of the secondary battery 10. I support it. In FIG. 8B, the support portion S is in direct contact with the exterior rings 144 and 148 to support the exterior rings 144 and 148 from the axially outer side of the secondary battery 10. In FIG. 8C, the outer rings 144 and 148 of the secondary battery 10 are supported by the support portion S from the radially outer side and the axially outer side of the secondary battery 10. That is, FIG. 8C is a support method in which the support method of FIG. 8A and the support method of FIG. 8B are combined.

  By supporting the exterior rings 144 and 148 having higher bending rigidity than the sheet exterior body 200, it is possible to prevent an external force that directly deforms the sheet exterior body 200 from acting on the support body S.

According to the embodiment described above, the following operational effects can be obtained.
(1) The upper lid unit 130 fixed to the upper end of the shaft core 115, the lower lid unit 140 fixed to the lower end of the shaft core 115, and the wound electrode group fixed to the upper lid unit 130 and the lower lid unit 140. A sealed space for accommodating the wound electrode group 110 was formed with the sheet outer package 200 disposed so as to cover the outer periphery of 110. The sheet exterior body 200 has a laminated structure in which a resin is laminated on a metal foil. Thus, by supporting the upper lid unit 130 and the lower lid unit 140 (see FIG. 8), when a vibration or impact is applied to the secondary battery 10 through the support portion, the wound electrode group in the sealed space. It can suppress that 110 vibrates.

  In the secondary battery described in Patent Document 1, the external terminal is connected to the sheet-like electrode constituting the wound electrode group directly or via a lead body or the like inside the sheet exterior body. The group is held by external terminals that are taken out from both ends of the sheet outer package. For this reason, when a vibration or impact acts on the secondary battery, the wound electrode group vibrates in the sheet exterior body, and the connection portion between the sheet-like electrode and the external terminal constituting the wound electrode group (or the sheet-like electrode and the lead) There is a risk that the secondary battery may be damaged, such as damage to the connection part with the body. On the other hand, according to the present embodiment, since the wound electrode group 110 can be suppressed from vibrating in the sealed space, the risk of damage to the secondary battery due to vibration and impact can be reduced. That is, according to the present embodiment, it is possible to provide the secondary battery 10 having excellent vibration resistance.

(2) The upper lid unit 130 and the lower lid unit 140 are respectively connected to current collecting rings 127 and 121 connected to current collecting tabs 116 and 117 formed on the electrodes, and externally connected to the current collecting rings 127 and 121. Terminals 133 and 145, exterior rings 144 and 148 to which the sheet exterior body 200 is fixed, and exterior rings 144 and 148, current collecting rings 127 and 121, and external terminals 133 and 145 as insulators Gaskets 143 and 147 are included. Current collecting rings 127 and 121 and external terminals 133 and 145 are fixed by caulking exterior rings 144 and 148 via gaskets 143 and 147. As described above, when the current collecting tabs 116 and 117 are connected to the current collecting rings 127 and 121, the connecting portions are weak in strength as compared with other components. However, in the present embodiment, since the vibration of the wound electrode group 110 in the sealed space can be suppressed, the connection portion between the current collecting tabs 116 and 117 and the current collecting rings 127 and 121 is damaged. Can be prevented.

(3) The metal foil of the sheet outer package 200 and the outer rings 144 and 148 are each made of a stainless material. For this reason, according to this Embodiment, compared with the case where the sheet | seat exterior body 200 is formed using the laminate film which consists of aluminum metal foil and a resin sheet, an improvement in intensity | strength can be aimed at. Thereby, when the internal pressure of a battery rises, it can prevent that a metal foil fractures | ruptures due to the tensile stress which acts on the metal foil of the sheet | seat exterior body 200, before a current interruption mechanism and a gas discharge mechanism operate | move.

(4) In the secondary battery 10, the upper lid unit 130 is provided with a current interruption mechanism. By providing a current interruption mechanism in at least one lid unit, when the pressure inside the container becomes high, the secondary battery 10 can be protected by stopping charging or discharging.

(5) The liquid injection hole 145c is provided in the lower lid unit 140. By providing the liquid injection hole 145c in at least one lid unit, a space capable of accommodating the electrolytic solution 105 is defined by the sheet exterior body 200, the upper lid unit 130, and the lower lid unit 140, and then the liquid injection hole 145c. The electrolytic solution 105 can be injected via

(6) A gas discharge mechanism is provided in both the upper lid unit 130 and the lower lid unit 140. Thereby, when the gas is generated due to heat generation due to abnormality such as overcharge and the pressure inside the container becomes high, the gas discharge mechanism of either or both of the upper lid unit 130 and the lower lid unit 140 is operated. Thus, the gas can be effectively discharged from the inside and the pressure in the container can be reduced.

(7) Patent Document 1 describes a configuration in which a current is interrupted in response to a signal from a strain gauge before the sheet exterior body is destroyed. However, in such a configuration, if a problem such as the signal wiring being cut occurs, current interruption may not be performed properly.

  On the other hand, according to the present embodiment, the wound electrode group 110 can be firmly fixed in the sealed space, and therefore a mechanism that can mechanically cut off current and discharge gas without control. (A current interruption mechanism and a gas discharge mechanism) can be provided. For this reason, in the present embodiment, it is possible to more reliably realize the interruption of the current and the discharge of the gas at an arbitrary pressure lower than the pressure at which the sheet exterior body 200 is destroyed, as compared with the technique of Patent Document 1. it can.

(8) As shown in FIG. 7, a cylindrical sheet exterior body 200 is prepared in advance, and the power generation unit 100 is inserted into the sheet exterior body 200 so that the sheet exterior body 200 and the exterior ring 144 are welded. . For this reason, according to the present embodiment, compared with the case where the overlapping portion 201 is laser-welded after the laminate film that is the material of the sheet outer package 200 is wound around the power generation unit 100, the thermal influence on the wound electrode group 110 is increased. Can be reduced.

(9) The overlapping portion 201 was formed by bringing the inner peripheral surface of one end of the laminate film into contact with the outer peripheral surface of the other end, and laser welding was performed. Thereby, compared with butt welding, the joint strength of the edge parts of a laminate film can be improved.

(10) By the way, in the case of a cylindrical secondary battery, in recent years, in order to increase the capacity of the battery, rather than expanding the diameter and winding many electrodes, the elongated shape has an increased area in the axial direction from the viewpoint of heat dissipation. There is a growing demand for shaped batteries. However, when a metal battery can is formed by deep drawing or the like, there is a problem that it is difficult to form the battery can into an elongated shape. In this embodiment mode, a long and thin laminate film may be rolled into a cylindrical shape, so that an elongated battery can be easily manufactured.

(11) At the upper end portion of the shaft core 115, a fitting portion 151 that fits with the positive electrode current collecting ring 127 that is a constituent member of the upper lid unit 130 is provided. A fitting portion 151 that fits with the negative electrode current collecting ring 121 that is a constituent member of the lower lid unit 140 is provided at the lower end portion of the shaft core 115. Each tip part of the fitting part 151 at both ends of the shaft core 115 is formed in a tapered shape. Accordingly, the upper lid unit 130 and the shaft core 115 can be easily fitted and fixed, and the lower lid unit 140 and the shaft core 115 can be easily fitted and fixed.

The following modifications are also within the scope of the present invention, and one or a plurality of modifications can be combined with the above-described embodiment.
(Modification 1)
The manufacturing method of the secondary battery 10 is not limited to the above-described embodiment.
(Modification 1-1)
In the sheet exterior body manufacturing step S100, when the laminate film is rolled into a cylindrical shape, a method may be employed in which the inner peripheral surfaces of both end portions are bonded together and welded. However, in this case, the welded portion that has been pasted out protrudes to the outside as an ear, which may be undesirable in the subsequent process. For this reason, it is preferable to overlap and weld the inner peripheral surface of the one end part of a laminate film on the outer peripheral surface of the other end part like the embodiment mentioned above.

(Modification 1-2)
In the sheet exterior body manufacturing step S100, when the laminate film is rolled into a cylindrical shape, a method may be employed in which the end faces of both end portions are butted and welded. As in the above-described embodiment, no step is formed in the overlapping portion 201. In the embodiment described above, a gap is generated between the inner peripheral surface of the end portion disposed on the outer peripheral side and the outer rings 144 and 148 among the end portions of the laminated film. A gap can be prevented from being generated. As a result, according to this modification, it is possible to improve the welding strength between the sheet outer package 200 and the outer rings 144 and 148.

(Modification 2)
In the present specification, various shapes can be adopted as the shape of each constituent member as long as it is configured to achieve the effects of the present invention. For example, in the present specification, the cylindrical shape, the columnar shape, the circular shape, the elliptical columnar shape, and the rectangular shape are not limited to a complete cylindrical shape, a cylindrical shape, a circular shape, an elliptical columnar shape, and a rectangular shape. Including substantially cylinders, cylinders, circles, elliptic cylinders, and rectangles.

(Modification 3)
In the above-described embodiment, the example in which the current blocking mechanism is provided in the upper lid unit 130 on the positive electrode side and the liquid injection hole 145c is provided in the lower lid unit 140 on the negative electrode side has been described, but the present invention is not limited to this. . A current interruption mechanism may be provided in the lower lid unit 140 on the negative electrode side, and a liquid injection hole 145c may be provided in the upper lid unit 130 on the positive electrode side.

  Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other embodiments conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Secondary battery, 100 Electric power generation unit, 105 Electrolyte, 110 Winding electrode group, 111 Positive electrode, 111a Positive electrode metal foil, 111b Positive electrode mixture layer, 111c Positive electrode foil exposed part, 112 Negative electrode, 112a Negative electrode metal foil, 112b Negative electrode mixture layer, 112c negative electrode foil exposed portion, 113 first separator, 114 second separator, 115 axial core, 115c hollow portion, 116 positive electrode tab, 117 negative electrode tab, 119 adhesive tape, 121 negative electrode current collecting ring, 121a base, 121b fitting cylinder part, 121c lower cylinder part, 121d collar part, 121e opening part, 122 holding member, 127 positive current collecting ring, 127a base part, 127b fitting cylinder part, 127c upper cylinder part, 127d collar part, 127e opening part 128 Pressing member, 130 Upper lid unit, 133 Positive external terminal 133a Peripheral part, 133b Terminal part, 133c Opening part, 134 Insulating plate, 134a Opening part, 134b Tube part, 135 Connection plate, 135a Protruding part, 135b Opening part, 137 Diaphragm, 137a Notch, 137b Side wall, 139 Positive electrode lead member 140, lower lid unit, 143 gasket, 143a base, 143b outer wall, 144 exterior ring, 144a inner contact, 144b outer wall, 144c outer contact, 145 negative external terminal, 145a notch, 145b recess, 145c Injection hole, 146 sealing plug, 146a base, 146b protrusion, 147 gasket, 147a base, 147b outer wall, 148 exterior ring, 148a outer contact, 148b outer wall, 148c inner contact, 150 捲Kaito, 151 Engaging portion, 152 groove, 153 hook,-out 154 notches, 200 sheets exterior body, 201 overlapping portion, 210 weld 220a weld 220b weld 230 reinforcing welds

Claims (5)

A cylindrical secondary battery having a wound electrode group in which an electrode and a separator are wound on a shaft core,
A first lid member fixed to one end of the shaft core; a second lid member fixed to the other end of the shaft core; and the wound electrode fixed to the first lid member and the second lid member With a sheet outer package disposed so as to cover the outer periphery of the group, a sealed space for accommodating the wound electrode group is formed,
The sheet outer package is a cylindrical secondary battery having a laminated structure in which a resin is laminated on a metal foil. The cylindrical secondary battery according to claim 1,
Each of the first lid member and the second lid member includes a current collecting ring connected to a current collecting tab formed on the electrode, an external terminal connected to the current collecting ring, and the sheet exterior body. An exterior ring to be fixed, and an insulator disposed between the exterior ring and the current collecting ring and the external terminal,
The current collector ring and the external terminal are fixed to each other by caulking the exterior ring via the insulator. The cylindrical secondary battery according to claim 2,
The metal foil of the sheet exterior body and the exterior ring are each a cylindrical secondary battery made of a stainless material. The cylindrical secondary battery according to any one of claims 1 to 3,
A current interrupting mechanism is provided in either one of the first lid member and the second lid member,
A liquid injection hole is provided in either one of the first lid member and the second lid member,
A cylindrical secondary battery in which a gas discharge mechanism is provided on both the first lid member and the second lid member. The cylindrical secondary battery according to any one of claims 1 to 4,
A first fitting portion that is fitted to a component of the first lid member is provided at one end of the shaft core,
A second fitting portion that is fitted to a constituent member of the second lid member is provided at the other end of the shaft;
Each tip part of the first fitting part and the second fitting part is a cylindrical secondary battery formed in a tapered shape.

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