JP2014139904A - Square secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a square secondary battery which reliably and stably interrupts current when an internal pressure increases.SOLUTION: A square secondary battery 1 comprises: a battery cover 21 which seals a battery container 2 incorporating an electrode group 3; a through hole 21b mounted on the battery cover 21; a connecting terminal 52 inserted into the through hole 21b via an insulator 22; a lead 41 connected to the connecting terminal 52 inside the battery; and a diaphram 42 connected to the lead 41, in which the diaphram 42 is connected to a current collector plate 53 electrically connected to the electrode groupe 3 and has a curent interruption structure such that conduction between the connecting terminal 52 and the electrode groupe 3 is cut off by an increase of pressure inside the battery container, and the lead 41 is flat and fixes the diaphram 42 by the lead 41 via a sealing material 43.

Description

  The present invention relates to a prismatic secondary battery used for in-vehicle applications and the like.

  Conventionally, in a sealed lithium ion secondary battery mounted on a vehicle or other equipment, gas is accumulated inside due to overcharge, excessive temperature rise, damage due to external force, etc. Pressure may increase. Therefore, a weak point for safety is formed in the battery case of the sealed battery.

  For example, there is a battery case in which a member that is deformed by the internal pressure of the battery is used at a part of the battery case, and the fragile portion is damaged by the deformation of the member. There have been proposed ones in which a current path is interrupted due to breakage of a fragile portion, and ones in which the inside and outside of a sealed battery are communicated to discharge gas.

  In Patent Document 1, a sealing body lead and a diaphragm are provided between the external electrode terminal and the internal current collecting tab, and a peripheral edge of the diaphragm is sealed to a cylindrical sealing body lead extending in a direction perpendicular to the battery lid. It is said that when the battery internal pressure rises, the diaphragm is deformed and the fragile portion is broken, thereby interrupting the current path.

JP 2008-66255 A

  However, in the above-described conventional technology, for example, when the periphery of the diaphragm is sealed with a cylindrical sealing body lead extending in a direction perpendicular to the battery lid, the thickness portion of the sealing body lead to which the diaphragm is welded, or further processing Since the shape of the part to which is added becomes complicated and the flatness is difficult to be obtained, there is a possibility that the welding becomes unstable.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a prismatic secondary battery that can reliably and stably interrupt a current path when the internal pressure increases. It is.

  The prismatic secondary battery of the present invention that solves the above problems includes a battery container containing a flat electrode group, a battery lid that seals the battery container, and a connection terminal that is inserted through an opening that opens in the battery lid. A lead disposed in the battery container and connected to the connection terminal; a diaphragm connected to the lead and penetrating the connection terminal; and a diaphragm deformed by an increase in internal pressure of the battery container; The diaphragm is connected to a current collector plate electrically connected to the electrode group, and has a current blocking structure that cuts off the electrical connection between the connection terminal and the electrode group when the pressure inside the battery container increases. In the secondary battery, the diaphragm is caulked and fixed to the lead.

  According to the present invention, it is possible to obtain a rectangular secondary battery that reliably and stably cuts off current when the internal pressure increases. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

The external appearance perspective view of a square secondary battery. The disassembled perspective view of a square secondary battery. The exploded perspective view of an electrode group. The exploded perspective view of a lid assembly. Sectional drawing of a square secondary battery. The top view and sectional view on the AA line of a square secondary battery. The fragmentary sectional view of the positive electrode terminal composition part. The fragmentary sectional view of a negative electrode terminal structure part. Sectional drawing which shows the state before the electric current interruption structure of the positive electrode terminal structure part shown in FIG. 7 act | operates. Sectional drawing which shows the state after the electric current interruption structure act | operates. Sectional drawing explaining the structural example of the crimping | crimped part in 1st Embodiment. Sectional drawing explaining the method of crimping and fixing a diaphragm. Sectional drawing explaining the method of crimping and fixing a diaphragm. Sectional drawing explaining the method of crimping and fixing a diaphragm. Sectional drawing explaining the method of crimping and fixing a diaphragm. Sectional drawing explaining the structural example of the caulking part in 2nd Embodiment. Sectional drawing explaining the structural example of the crimping | crimped part in 3rd Embodiment.

  Next, embodiments of the present invention will be described below with reference to the drawings. In the following description, as an example of a prismatic secondary battery, a case of a prismatic lithium ion secondary battery used as a power source for an electric vehicle or a hybrid vehicle will be described as an example, but the present invention is not limited thereto. The present invention can also be applied to other prismatic secondary batteries.

[First Embodiment]
FIG. 1 is an external perspective view of a prismatic secondary battery according to the present embodiment, and FIG. 2 is an exploded perspective view of the prismatic secondary battery shown in FIG.

  As shown in FIGS. 1 and 2, the lithium ion secondary battery 1 that is a prismatic secondary battery has a configuration in which an electrode group 3 is accommodated in a battery container 2. The battery container 2 includes a battery can 11 having an opening 11 a and a battery lid 21 that seals the opening 11 a of the battery can 11. The electrode group 3 has a structure in which the separators 32 and 34 are interposed between the positive electrode plate 33 and the negative electrode plate 31, wound in a flat shape, and fixed with a tape 35.

  The battery can 11 and the battery lid 21 are both made of an aluminum alloy, and the battery lid 21 is welded to the battery can 11 by laser welding. The battery lid 21 is provided with a positive electrode terminal component 50 and a negative electrode terminal component 60 to constitute the lid assembly 4.

  The positive electrode terminal component 50 and the negative electrode terminal component 60 have a positive electrode connection terminal 52 and a negative electrode connection terminal 62 (a pair of electrode terminals). The positive electrode connection terminal 52 is disposed between the battery lid 21 via the positive electrode external insulation member 22, and the negative electrode connection terminal 62 is disposed between the battery lid 21 and the negative electrode external insulation member 23. Yes.

  In addition to the positive electrode terminal component 50 and the negative electrode terminal component 60, the battery lid 21 is opened when the pressure in the battery container 2 rises above a predetermined value, and discharges the gas in the battery container 2. A valve 71 and a liquid injection port 72 for injecting an electrolytic solution into the battery container 2 are disposed.

  The positive electrode connection terminal 52 and the negative electrode connection terminal 62 are disposed at positions separated from each other on one side and the other side in the longitudinal direction of the battery lid 21. The positive electrode connection terminal 52 and the negative electrode connection terminal 62 have a positive electrode external terminal 51 and a negative electrode external terminal 61 disposed on the outside of the battery lid 21, respectively. The positive electrode connection terminal 52 is made of an aluminum alloy, and the negative electrode connection terminal 62 is made of a copper alloy.

  The positive electrode terminal component 50 and the negative electrode terminal component 60 include a positive electrode current collector plate 53 and a negative electrode current collector plate 63 that extend from the inside of the battery lid 21 toward the bottom of the battery can 11 and are conductively connected to the electrode group 3. Each has. The electrode group 3 is disposed and supported between the positive electrode current collector plate 53 and the negative electrode current collector plate 63, and the power generation element assembly 5 is configured by the lid assembly 4 and the electrode group 3.

FIG. 3 is an external perspective view showing the details of the electrode group 3 shown in FIG.
The electrode group 3 is configured by stacking a positive electrode plate 33, a separator 32, a negative electrode plate 31, and a separator 34 in this order and winding them in a flat shape. As shown in FIG. 3, in the electrode group 3, the outermost electrode plate is the negative electrode plate 31, and the separator 34 is wound further outside.

  The separators 32 and 34 have a role of insulating the positive electrode plate 33 and the negative electrode plate 31. The negative electrode coating portion 31a of the negative electrode plate 31 is larger in the width direction than the positive electrode coating portion 33a of the positive electrode plate 33, so that the positive electrode coating portion 33a is always sandwiched between the negative electrode coating portions 31a. Yes.

  The positive electrode uncoated portion 33b and the negative electrode uncoated portion 31b are bundled at a plane portion and connected to current collector plates 53, 63 connected to the positive and negative external terminals 51, 61 by welding or the like. The separators 32 and 34 are wider than the negative electrode coated portion 31a in the width direction, but are bundled because they are wound at positions where the metal foil surface is exposed at the positive electrode uncoated portion 33b and the negative electrode uncoated portion 31b. This will not interfere with welding.

  The positive electrode plate 33 has a positive electrode coating portion 33a in which a positive electrode active material mixture is applied on both surfaces of a positive electrode foil that is a positive electrode current collector, and a positive electrode active portion 33 is disposed at one end in the width direction of the positive electrode foil. A positive electrode uncoated portion (foil exposed portion) 33b to which no material mixture is applied is provided.

  The negative electrode plate 31 has a negative electrode coating part 31a in which a negative electrode active material mixture is applied to both surfaces of a negative electrode electrode foil that is a negative electrode current collector, and a negative electrode active part is disposed at the other end in the width direction of the positive electrode foil. A negative electrode uncoated portion (foil exposed portion) 31b to which the material mixture is not applied is provided. The positive electrode uncoated portion 33b and the negative electrode uncoated portion 31b are regions where the metal surface of the electrode foil is exposed. As shown in FIG. 3, the winding axis direction (X direction) is on one side and the other side. Wound to be placed.

  In the negative electrode plate 31, 10 parts by weight of polyvinylidene fluoride (hereinafter referred to as PVDF) is added as a binder to 100 parts by weight of amorphous carbon powder as a negative electrode active material, and N as a dispersion solvent. -A negative electrode mixture in which methylpyrrolidone (hereinafter referred to as NMP) was added and kneaded was prepared. This negative electrode mixture was applied to both surfaces of a 10 μm thick copper foil (negative electrode foil) leaving the current collecting part (negative electrode uncoated part 31b). Then, the negative electrode active material application part thickness 70 micrometer negative electrode plate 31 which does not contain copper foil was obtained by drying, pressing, and cutting.

  In this embodiment, the case where amorphous carbon is used as the negative electrode active material is exemplified, but the present invention is not limited to this, and natural graphite capable of inserting and removing lithium ions and various artificial graphites are not limited thereto. The material may be a carbonaceous material such as a material or coke, and the particle shape is not particularly limited to a scale shape, a spherical shape, a fiber shape, a lump shape, or the like. However, in any carbonaceous material, the negative electrode active material application portion expands due to occlusion of lithium ions.

For positive electrode plate 33, 10 parts by weight of flaky graphite as a conductive material and 10 parts by weight of PVDF as a binder are added to 100 parts by weight of lithium manganate (chemical formula LiMn ₂ O ₄ ) as a positive electrode active material. A positive electrode mixture was prepared by adding and kneading NMP as a dispersion solvent. This positive electrode mixture was applied to both surfaces of an aluminum foil (positive electrode foil) having a thickness of 20 μm, leaving a solid current collecting portion (positive electrode uncoated portion 33b). Thereafter, drying, pressing, and cutting were performed to obtain a positive electrode plate 33 having a thickness of 90 μm, which does not include an aluminum foil.

  Further, in the present embodiment, the case where lithium manganate is used as the positive electrode active material is exemplified, but other lithium manganate having a spinel crystal structure or a lithium manganese composite oxide partially substituted or doped with a metal element or A lithium cobalt oxide or lithium titanate having a layered crystal structure, or a lithium-metal composite oxide in which a part thereof is substituted or doped with a metal element may be used.

  Moreover, in this Embodiment, although illustrated about the case where PVDF is used as the binder of the coating part in the positive electrode plate 33 and the negative electrode plate 31, polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile Polymers such as rubber, styrene butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene fluoride, acrylic resins, and mixtures thereof Can be used.

  4 is an exploded perspective view of the lid assembly shown in FIG. 2, FIG. 5 is a sectional view of the prismatic secondary battery, and FIG. 6 is a plan view of the prismatic secondary battery and a sectional view taken along line AA of the plan view. 7 is a partial cross-sectional view of the positive electrode terminal constituting portion of the lid assembly 4 shown in FIG. 5, and FIG. 8 is a partial cross-sectional view of the negative electrode terminal constituting portion. 9 is a cross-sectional view showing a state before the current interrupting structure of the positive electrode terminal component shown in FIG. 7 is activated, and FIG. 10 is a cross-sectional view showing a state after the current interrupting structure is activated.

  As shown in FIG. 4, the positive electrode terminal component 50 includes a positive electrode external terminal 51, a positive electrode connection terminal 52, a gasket 26, a positive electrode external insulation member 22, a lead 41, a seal member 43, a diaphragm 42, a positive electrode internal insulation member 24, a positive electrode A current collecting plate 53 is provided. The positive electrode connection terminal 52 is interposed between the battery lid 21 and the gasket 26, the positive electrode internal insulating member 24, and the lead 41. The positive electrode connection terminal 52 is electrically insulated from the battery lid 21, and the distal end of the fixed shaft 52 c faces the outer diameter side. The intervening parts are held by bending and caulking.

  As shown in FIGS. 5 and 6, the positive electrode current collector plate 53 is fixed to the battery lid 21 via the positive electrode internal insulating member 24. The battery lid 21 is provided with a convex portion 21 a that fixes the positive electrode internal insulating member 24 to the battery lid 21 by being inserted into the fixing hole 24 b of the positive electrode internal insulating member 24 and caulked. For example, as shown in the AA line cross-sectional view of FIG. 6, the convex portion 21 a is provided at two locations on the battery inner surface of the battery lid 21, and is inserted into the fixing hole 24 b of the positive electrode internal insulating member 24, and the convex portion 21 a. The positive electrode internal insulating member 24 is held by caulking and fixing the tip of the positive electrode.

  The positive electrode internal insulation member 24 is pin-shaped to fix the positive electrode current collection plate 53 to the positive electrode internal insulation member 24 by being inserted into a support hole 53c formed in the base 53d of the positive electrode current collection plate 53 and caulking. A portion 24a is provided. The holding portions 24a are provided, for example, at four locations, and are inserted into the support holes 53c (see FIG. 4) of the positive electrode current collector plate 53 to hold the positive electrode current collector plate 53 by applying heat to deform the tip. To do.

  The battery lid 21 and the positive electrode internal insulating member 24 are fixed to each other by the convex portion 21a, and the positive electrode internal insulating member 24 and the positive electrode current collector plate 53 are fixed to each other by the holding portion 24a. A positive electrode current collector plate 53 is integrated.

  As shown in FIG. 4, the negative electrode terminal component 60 includes a negative electrode external terminal 61, a negative electrode connection terminal 62, a gasket 26, a negative electrode external insulating member 23, a negative electrode internal insulating member 25, and a negative electrode current collector plate 63. The negative electrode connection terminal 62 is interposed between the battery lid 21 and the gasket 26, the negative electrode internal insulating member 25, and the negative electrode current collector plate 63. The negative electrode connection terminal 62 is electrically insulated from the battery lid 21. The intervening parts are held by bending to the radial side and caulking. The negative electrode connection terminal 62 and the negative electrode current collector plate 63 are joined by, for example, laser welding and are electrically connected.

  The positive electrode terminal component 50 has a current interrupting structure that interrupts current when the battery internal pressure increases. The current interruption structure is provided in a current path from the positive electrode connection terminal 52 to the positive electrode current collector plate 53.

  As shown in FIG. 7, the positive electrode connection terminal 52 is caulked and fixed between the battery lid 21 via a gasket 26, a positive electrode internal insulating member 24, and a lead 41. The lead 41 is crimped and electrically connected to the positive electrode connection terminal 52 inside the battery lid 21. As shown in FIG. 9, a diaphragm 42 is caulked and fixed to the lead 41 via a seal member 43.

  In the diaphragm 42, the central portion of the curved surface portion 42a and the joint portion 53a of the positive electrode current collector plate 53 are joined by, for example, laser welding, and are electrically connected to each other. The diaphragm 42 is connected to the lead 41, closes the through hole 52 d of the positive electrode connection terminal 52, and is deformed by an increase in the internal pressure of the battery container 2.

  A fragile portion 53 b is provided around the joint portion 53 a of the positive electrode current collector plate 53. When the diaphragm 42 of the positive electrode connection terminal 52 is deformed due to an abnormal increase in battery internal pressure, the fragile portion 53b of the positive electrode current collector plate 53 is broken, thereby cutting off the electrical connection. Thereby, the abnormal operation | movement of a battery can be stopped reliably and safely, maintaining the airtightness in a battery.

  The diaphragm 42 has a dome shape that protrudes toward the inside of the battery, and is deformed in a direction in which the height of the central portion, which is the top, becomes lower due to an increase in battery internal pressure, so that the junction of the positive electrode current collector plate 53 53a is urged toward the battery outer side (upward in FIG. 4) which is a direction orthogonal to the base 53d, the fragile portion 53b is broken to separate the joint 53a from the base 53d, and between the positive electrode current collector plate 53 It is configured to cut off the electrical connection.

Next, the structure of the positive electrode terminal structure part 50 in this embodiment is demonstrated in detail.
As shown in FIG. 4, the positive electrode connection terminal 52 includes a flat plate portion 52 a disposed along the upper surface that is outside the battery lid 21, and an insertion hole 52 b that opens into the flat plate portion 52 a and supports the positive external terminal 51. And a fixed shaft 52c that is inserted through the opening 21b of the battery cover 21 and penetrates the battery cover 21, and the tip protrudes into the battery on the back side of the battery cover 21, and the fixed shaft 52c includes A through hole 52d penetrating the center in the axial direction is provided.

  The positive electrode external terminal 51 includes a shaft portion 51a inserted into the insertion hole 52b of the positive electrode connection terminal 52, and a rectangular flat plate head portion 51b interposed and supported between the flat plate portion 52a and the positive electrode external insulating member 22. have. The shaft 51a is screwed with a thread that can be screwed into a nut to fasten the bus bar.

  The positive electrode external insulating member 22 is an insulating plate-like member interposed between the head portion 51 b of the positive electrode external terminal 51 and the upper surface of the battery lid 21, and communicates with the opening 21 b of the battery lid 21 to be positively connected. An opening 22a for inserting the fixed shaft 52c of the terminal 52 is provided.

  The gasket 26 has a ring shape with an L-shaped cross section that is fitted around the fixed shaft 52 c of the positive electrode connection terminal 52. The gasket 26 is inserted into the opening 21 b of the battery lid 21 and is fixed to the fixed shaft 52 c of the positive electrode connection terminal 52. The terminal sealing part which insulates and seals between the battery cover 21 is comprised. The gasket 26 is interposed between the flat plate portion 52a of the positive electrode connection terminal 52 and the battery lid 21 in a compressed state with a predetermined compression force by caulking the tip of the fixed shaft 52c of the positive electrode connection terminal 52.

  The positive electrode internal insulating member 24 is configured by an insulating plate-like member made of a synthetic resin material disposed along the lower surface of the battery lid 21, and is provided between the battery lid 21 and the lead 41 and between the battery lid and the battery lid 21. 21 and the positive electrode current collector plate 53 to insulate them. The positive electrode internal insulating member 24 has a predetermined plate thickness, and is provided with a through hole 24 c that communicates with the opening 21 b of the battery lid 21 and through which the fixed shaft 52 c is inserted. A part of the positive electrode internal insulating member 24 is interposed between the lead 41 and the battery lid 21, and is caulked and fixed to the battery lid 21 together with the positive electrode connection terminal 52 by caulking the tip of the fixed shaft 52 c. Has been.

  The positive electrode internal insulating member 24 is provided with a recess 24d communicating with the through hole 24c and accommodating the lead 41 and the diaphragm 42. As shown in FIG. 7, the recess 24 d is recessed in the lower surface of the positive electrode internal insulating member 24 and communicates with other space portions inside the battery.

  As shown in FIG. 4, the positive electrode internal insulating member 24 is provided with a plurality of fixing holes 24 b for fixing the positive electrode internal insulating member 24 to the battery lid 21 on the upper surface thereof. At a position facing the hole 24b, a convex portion 21a inserted through the fixed hole 24b is provided.

  The positive electrode internal insulating member 24 protrudes from the fixing hole 24b in a state where the convex portion 21a of the battery lid 21 is inserted into the fixing hole 24b and the upper surface of the positive electrode internal insulating member 24 is in contact with the lower surface of the battery lid 21. The tip of the convex portion 21a is crimped and engaged with the battery lid 21 by expanding the diameter by pressure deformation (see FIG. 6). The convex portion 21a of the battery lid 21 is formed by making the outer side of the battery concave by pressing in advance and making the inner side of the battery convex by that amount.

  A plurality of holding portions 24a for fixing the positive electrode current collector plate 53 are provided on the lower surface of the positive electrode internal insulating member 24 (see FIGS. 4 and 6). The plurality of holding portions 24a are respectively inserted into the plurality of support holes 53c provided in the base portion 53d of the positive electrode current collector plate 53, and are crimped by expanding the diameter by heating and deforming the tips protruding from the support holes 53c. . Further, when heating the plurality of holding portions 24 a, the current collector plate 53 is also heated together to thermally weld the base portion 53 d to the positive electrode internal insulating member 24. Therefore, the positive electrode current collecting plate 53 is integrally fixed to the positive electrode internal insulating member 24.

  The diaphragm 42 has a dome-shaped curved surface portion 42a that gradually decreases in diameter as it moves in the axial direction, and a flange portion 42b that expands radially outward from the outer peripheral edge of the curved surface portion 42a. The flange portion 42b expands along one plane toward the radially outer side, continues at a constant width over the entire circumference, and has a ring shape that is disposed in a groove 41b of the lead 41 described later. .

  The diaphragm 42 has a curved surface portion 42a facing and covering the opening end of the through hole 52d that opens to the lower end of the fixed shaft 52c, and the flange portion 42b is caulked and fixed to the lead 41 so as to hermetically seal between the leads. The space outside the battery and the space inside the battery communicated by the through hole 52d is partitioned.

  When the internal pressure of the battery case 2 rises above a preset upper limit value, the curved surface portion 42a is plastically deformed in a direction in which the height of the central portion is lowered due to a pressure difference from the outside of the battery case 2, and the positive electrode The fragile portion 53b of the current collector plate 53 is broken, and the material, plate thickness, cross-sectional shape, etc. are maintained so that the joint portion 53a is held at a position completely separated from the base portion 53d of the positive electrode current collector plate 53 even after the internal pressure is reduced. Is set. The central portion, which is the top of the curved surface portion 42a, is joined to the joint portion 53a of the positive electrode current collector plate 53 by laser welding. The joining of the central portion may be performed by resistance welding or ultrasonic welding in addition to laser welding.

  The curved surface portion 42a is gradually reduced in diameter as it moves in a direction away from the lead 41 along the central axis direction continuously to the flange portion 42b, and a first inclined surface portion having a linear cross section, and a first inclined surface portion And a second inclined surface portion that is bent continuously and extends at an inclination angle different from that of the first inclined surface portion and has a linear cross section.

  The curved surface portion 42a is deformed so as to move in the direction in which the first inclined surface portion expands due to the increase of the battery internal pressure, and the second inclined surface portion moves in the direction in which the height position of the central portion is lowered. The first inclined surface portion has an inclination angle smaller than 45 ° with respect to the central axis direction of the curved surface portion 42a, and the second inclined surface portion has an outer angle larger than 180 ° with respect to the first inclined surface portion. The inclination angle is as follows.

  As shown in FIG. 4, the positive electrode current collector plate 53 has a flat plate-like base portion 53 d that extends in parallel to face the lower surface of the battery lid 21, and a plurality of support holes 53 c have four corner positions, for example, They are formed so as to penetrate each other at a predetermined interval.

  A plurality of holding portions 24 a protruding from the lower surface of the positive electrode internal insulation member 24 are inserted into the plurality of support holes 53 c and caulked, and the positive electrode current collector plate 53 is integrated with the positive electrode internal insulation member 24. It is fixed by caulking.

  The base 53d is provided with a pair of edges formed by bending in a direction away from the battery lid 21 along the pair of long sides, and the rigidity is improved so as to maintain a planar shape. The pair of joining pieces 53e of the positive electrode current collector plate 53 is provided so as to protrude continuously from each edge.

  The positive electrode current collector plate 53 is provided with a joint portion 53 a that is joined to the central portion of the diaphragm 42. As shown in FIG. 9, the joint portion 53a is configured by a thin portion in which a part of the base portion 53d is thinned. The fragile portion 53b is configured by providing a groove portion in a thin portion so as to surround the periphery of the joint portion 53a, and is fragile by a diaphragm 42 that deforms in the battery outward direction (upward in FIG. 9) when the battery internal pressure rises. The joint portion 53a can be separated from the base portion 53d by being broken at the portion 53b.

  The fragile portion 53b breaks when a force in the pulling direction is applied to the battery lid 21 side due to the deformation of the diaphragm 42 due to the increase in the internal pressure of the battery case 2, while it is broken under normal use environment such as vibration during traveling. The dimensions and the like are set so that the strength does not break. Joining of the center part of the diaphragm 42 and the joint part 53a of the positive electrode current collector plate 53 is performed by laser welding, but resistance welding, ultrasonic welding, and the like are also possible.

  In the current interrupting structure having the above-described configuration, when the internal pressure of the battery container 2 rises above a preset upper limit value, the diaphragm 42 is arranged in a direction in which the protrusion height decreases due to a pressure difference with the outside of the battery container 2. The joint 53a surrounded by the weak part 53b of the positive current collector plate 53 is pulled in a direction orthogonal to the base part 53d, and the weak part 53b of the positive current collector 53 is broken. And as shown in FIG. 10, the junction part 53a is isolate | separated from the base 53d, and the electric current path between the positive electrode connection terminal 52 and the positive electrode current collecting plate 53 is interrupted | blocked.

  The lead 41 is made of a conductive disk member, and has an opening 41 a (see FIG. 4) through which the fixed shaft 52 c of the positive electrode connection terminal 52 passes through the opening 21 b of the battery lid 21. Reference) is provided.

  As shown in FIGS. 7 and 9, the lead 41 is disposed to face the lower surface of the battery lid 21 with the positive electrode internal insulating member 24 interposed between the lead 41 and the battery lid 21. By extending and caulking the tip of the protruding fixed shaft 52c radially outward, it is integrally fixed to the battery lid 21 while being electrically connected to the positive electrode connection terminal 52 and insulated from the battery lid 21. In the lead 41, a caulking portion 52e at the tip of the fixed shaft 52c protrudes from the opening 41a, and a through hole 52d communicating with the outside of the battery opens toward the inside of the battery.

FIG. 11 is a cross-sectional view illustrating a configuration example of a caulking portion in the first embodiment, and is an enlarged view of a portion B in FIG.
As shown in FIG. 11, the lead 41 is provided with a caulking portion 41 d for caulking and fixing the diaphragm 42. The caulking portion 41 d is caulked and fixed by sandwiching the flange portion 42 b of the diaphragm 42 from both sides in the axial direction of the diaphragm 42.

  The lead 41 is continuously recessed in a circumferential shape on a flat surface 41g exposed to the inside of the battery, and the groove 41b into which the flange portion 42b of the diaphragm 42 is inserted, and the flange portion 42b at a radially outer position of the groove 41b. The outer peripheral wall portion 41c rises to face the outer peripheral end face.

  The caulking portion 41d is inserted between the flange portion 42b and the flange portion 42b via the seal member 43, and the flange portion 42b is inserted into the groove 41b, and the distal end side of the outer peripheral wall portion 41c is bent radially inward over the entire circumference. It is formed. The caulking portion 41d extends in parallel with the groove bottom of the concave groove 41b, and sandwiches the flange portion 42b between the groove bottom of the concave groove 41b.

  The lead 41 is hermetically sealed between the lead 42 and the diaphragm 42 by caulking and fixing the flange portion 42b with the caulking portion 41d. The lead 41 has an abutment surface 41f that abuts on the inner peripheral end portion 42c of the flange portion 42b, and is electrically connected to the diaphragm 42.

  The seal member 43 has a U-shaped cross-section that sandwiches the flange portion 42b from both axial sides of the diaphragm 42. Between the flange portion 42b and the groove bottom of the concave groove 41b, the flange portion 42b and the outer peripheral wall portion 41c Between the flange portion 42b and the caulking portion 41d. A portion of the seal member 43 interposed between the flange portion 42b and the caulking portion 41d has a size that protrudes toward the curved surface portion 42a from the tip of the caulking portion 41d.

  The caulking portion 41d has a distal end portion 41e that is bent closer to the flange portion 42b than the proximal end side of the caulking portion 41d, and a part of the distal end portion 41e is bitten into the seal member 43 ( (Indicated by arrows in FIG. 11). Therefore, a pressing point that most presses the sealing member 43 can be formed, and the sealing member 43 can be pressed against the flange portion 42b from the concave groove 41b to the pressing point, so that the sealing can be ensured.

12 to 15 are sectional views for explaining a method of caulking and fixing the diaphragm to the lead.
The lead 41 is caulked and fixed between the battery lid 21 and the battery lid 21 by caulking portions 52 e of the positive electrode connection terminal 52 via the positive electrode internal insulating member 24.

  As shown in FIG. 12, the seal member 43 and the diaphragm 42 are approached from the lower side of the lead 41, and as shown in FIG. 13, the flange portion 42b of the diaphragm 42 is inserted into the concave groove 41b via the seal member 43 therebetween. Insert. As shown in FIGS. 12 and 13, the seal member 43 has a flat surface portion that is in contact with the upper surface of the flange portion 42 b and an outer peripheral wall portion that is bent and rises at the outer peripheral edge of the flat surface portion. It has a substantially L-shaped ring shape.

  14, the distal end side of the outer peripheral wall portion 41c is bent radially inward over the entire circumference, and the flange portion 42b is sandwiched from both sides in the axial direction. As shown in FIG. It is clamped between the groove bottom and the caulking portion 41d.

  According to the configuration described above, since the flange portion 42b of the diaphragm 42 is fixed by caulking, the diaphragm 42 can be easily and reliably fixed to the lead 41 and hermetically sealed.

  For example, in the case of the conventional method in which the diaphragm and the lead are welded in a circumferential shape, there is a problem that the welding distance is long and poor welding is likely to occur. Moreover, there exists a problem that the reliability of sealing may be impaired by the roundness of a diaphragm and the shift | offset | difference of the diameter of a welding location. On the other hand, in this embodiment, since it is fixed by caulking, the above-described problem during welding does not occur, and the sealing reliability is high.

Next, a method for producing the positive electrode terminal component 50 having the above configuration will be described.
(1) Joining of the positive electrode connection terminal 52, the positive electrode external insulating member 22, the positive electrode internal insulating member 24, and the like and the battery lid 21 First, the positive electrode external insulating member 22 and the gasket 26 are connected to the battery lid 21 outside the battery lid 21. It arranges and aligns with the opening part 21b. Then, the head portion 51 b of the positive electrode external terminal 51 is inserted into a recess provided in the positive electrode external insulating member 22, and the shaft portion 51 a of the positive electrode external terminal 51 is inserted into the insertion hole 52 b of the positive electrode connection terminal 52.

  Then, inside the battery lid 21, the positive electrode internal insulating member 24 is interposed between the battery lid 21 and the lead 41 so that the through hole 24 c of the positive electrode internal insulating member 24 and the opening 41 a of the lead 41 are formed. The positive electrode internal insulating member 24 and the lead 41 are arranged so as to be arranged on a concentric circle. And the convex part 21a of the battery cover 21 is inserted in the fixing hole 24b of the positive electrode internal insulation member 24, and the front-end | tip of the convex part 21a is made to protrude from the fixing hole 24b.

  Then, the positive electrode connection terminal 52 is approached from the upper side which is the battery outer side of the battery lid 21, the flat plate portion 52 a of the positive electrode connection terminal 52 is superimposed on the positive electrode external insulating member 22, and the fixed shaft of the positive electrode connection terminal 52 is fixed. 52c is inserted from the outside of the battery lid 21 into the opening 22a of the positive electrode external insulating member 22, the gasket 26, the opening 21b of the battery lid 21, the through hole 24c of the positive electrode internal insulating member 24, and the opening 41a of the lead 41. After that, the tip of the fixed shaft 52c is caulked. The gasket 26 is interposed between the fixed shaft 52c and the battery lid 21 to insulate and seal between them.

  Along with the caulking of the fixed shaft 52c, the caulking of the convex portion 21a of the battery lid 21 is performed. The projecting portion 21 a has a tip that protrudes from the fixing hole 24 b of the positive electrode internal insulating member 24 and has its diameter expanded by caulking to fix the positive electrode internal insulating member 24 to the battery lid 21. The positive electrode internal insulating member 24 is fixed to the battery lid 21 by two types of caulking, that is, caulking of the fixed shaft 52c and caulking of the convex portion 21a.

(2) Joining between the lead 41 and the diaphragm 42 The flange portion 42b of the diaphragm 42 is inserted into the concave groove 41b of the lead 41, joined together by caulking, and hermetically sealed. The lead 41 has a dome shape so as to avoid the caulking portion 52e of the positive electrode connection terminal 52, and a larger surface area of the diaphragm 42 can be secured in a smaller space. Therefore, when the internal pressure of the battery container 2 rises, the diaphragm 42 is easily deformed, and a reliable current interruption can be performed at a lower pressure.

(3) Joining of the positive electrode current collector plate 53 to the positive electrode internal insulating member 24 and the diaphragm 42 The positive electrode current collector plate 53 is provided with several support holes 53c in the base 53d. A holding portion 24a that is inserted through the support hole 53c is provided at a position facing the support hole 53c on a certain battery inner plane portion. The positive electrode current collector plate 53 is engaged with the positive electrode internal insulating member 24 by inserting the holding portion 24a into the support hole 53c and heat-deforming the tip of the holding portion 24a to expand the diameter, and the upper surface of the base portion 53d is The positive inner insulating member 24 is fixed in contact with the lower surface.

  Then, the joint portion 53 a of the positive electrode current collector plate 53 is joined to the center portion of the diaphragm 42. The joint portion 53a of the positive electrode current collector plate 53 is joined to the center portion of the diaphragm 42 by welding. Laser welding, resistance welding, ultrasonic welding, friction stir welding, or the like is possible for joining the central portion of the diaphragm 42 and the joint portion 53a of the positive electrode current collector plate 53. The positive electrode terminal component 50 is manufactured through the steps (1), (2), and (3) described above.

  The positive electrode current collecting plate 53 is fixed to the positive electrode internal insulating member 24 by the holding portion 24a, and the positive electrode internal insulating member 24 is engaged with the battery lid 21 by the convex portion 21a. Vibration and shock from the positive current collector 53 can be transmitted to the positive electrode internal insulation member 24, and can be transmitted from the positive electrode internal insulation member 24 to the battery lid 21 to be diffused throughout the battery container 2. It is possible to suppress the adverse effect on the weak parts such as the part 53b and the joint part 53a.

  In addition, regarding the fixing of the positive electrode current collector plate 53 and the positive electrode internal insulating member 24, since the processing step is easy, the case where the holding portion 24a is thermally deformed and engaged and thermally welded is described as an example. If firm fixation is required, it is also possible to fix using at least one of a screw, a rivet, and an adhesive instead of or in combination with heat deformation. Similarly, regarding the fixation of the battery lid 21 and the positive electrode internal insulating member 24, the convex portion 21a provided on the battery lid 21 is inserted into the fixing hole 24b of the positive electrode internal insulating member 24 and the tip of the convex portion 21a is pressurized and deformed. The case where the positive electrode internal insulating member 24 is engaged is described as an example, but at least one of a screw, a rivet, and an adhesive is used instead of or in addition to the pressure deformation at the tip of the convex portion 21a. It is also possible to fix the positive electrode internal insulating member 24 using

  In the present embodiment, the positive electrode current collector plate 53, the diaphragm 42, and the lead 41 are formed of aluminum or an aluminum alloy. In the lithium ion secondary battery 1, when the positive electrode side is made of an aluminum alloy and the negative electrode side is made of a copper alloy, the aluminum alloy is more easily deformed and broken easily than the copper alloy. Therefore, in this embodiment, the current interruption structure is provided on the positive electrode side.

  In order to assemble the lithium ion secondary battery 1, the lid assembly 4 having the positive electrode terminal component 50 manufactured by the above method is assembled, and then the bonding piece 53 e of the positive current collector 53 and the negative current collector 63 are joined. The wound electrode group 3 is joined to the piece 63e, and the power generation element assembly 5 is assembled. Then, the periphery of the wound electrode group 3 is covered with an insulating sheet (not shown) together with the positive electrode current collector plate 53 and the negative electrode current collector plate 63 and inserted into the battery can 11, and the opening 11 a of the battery can 11 is connected to the battery. The lid 21 is closed, and the battery lid 21 is joined and sealed to the battery can 11 by laser welding.

  Then, an electrolytic solution is injected into the battery container 2 from the liquid injection port 72, the liquid injection port 72 is closed with a liquid injection plug 73, and the battery lid 21 is joined and sealed by laser welding. The lithium ion secondary battery 1 assembled by the above-described assembly work is charged / discharged with respect to the external electronic device connected by the positive electrode connection terminal 52 and the positive electrode external terminal 51 and the negative electrode connection terminal 62 and the negative electrode external terminal 61. It becomes possible.

The lithium ion secondary battery 1 can have the following effects.
The lithium ion secondary battery 1 of the present embodiment has a configuration in which a diaphragm 42 is caulked and fixed to a lead 41 and the lead 41 and the diaphragm 42 are hermetically sealed. Therefore, as compared with the conventional case, the sealing can be performed easily and reliably, and the sealing reliability can be improved. And since the sealing member 43 is interposed both between the flange part 42b and the groove bottom of the recessed groove 41b and between the flange part 42b and the caulking part 41d, it has high sealing performance.

  The caulking portion 41d has a distal end portion 41e that is bent closer to the flange portion 42b than the proximal end side of the caulking portion 41d, and a part of the distal end portion 41e is bitten into the seal member 43. Yes. Therefore, a pressing point that most presses the sealing member 43 can be formed, and the sealing member 43 can be pressed against the flange portion 42b from the recessed groove 41b to the pressing point, thereby improving the sealing performance. it can.

  In the lithium ion secondary battery 1 of the present embodiment, the curved surface portion 42a of the diaphragm 42 has a dome shape. It is possible to easily obtain a stress sufficient to deform the diaphragm 42 in a limited space and break the fragile portion 53b. Accordingly, the rigidity of the fragile portion 53b can be made relatively strong even when the same breaking pressure is set, and the fragile portion 53b is prevented from being broken by vibration or impact, and when the internal pressure rises, the current is reliably and stably maintained. The route can be blocked.

  In the lithium ion secondary battery 1, the fixed shaft 52 c of the positive electrode connection terminal 52 that penetrates the battery lid 21 is caulked, and the positive electrode connection terminal 52 outside the battery lid 21 and the positive electrode current collector plate 53 inside the battery lid 21 are connected. The positive electrode connection terminal 52 and the positive electrode current collector plate 53 are integrally fixed to the battery lid 21 while being electrically connected to each other. Further, in addition to caulking and fixing by the fixed shaft 52c, a structure in which the positive electrode internal insulating member 24 is engaged with the battery lid 21 by the convex portion 21a and the positive electrode current collecting plate 53 is fixed to the positive electrode internal insulating member 24 by the holding portion 24a. Have.

  Therefore, external vibration and impact applied to the positive electrode current collector plate 53 can be transmitted from the positive electrode current collector plate 53 to the positive electrode internal insulating member 24, and can be transmitted from the positive electrode internal insulating member 24 to the battery lid 21. Compared with the case of only caulking and fixing by the fixing shaft 52c of 52, it is possible to prevent a load from being applied to a fragile portion such as the gasket 26 and the caulking portion 52e, and to maintain hermeticity.

  The positive electrode internal insulating member 24 is fixed to the battery lid 21 on the battery outer side, and is fixed to the positive electrode current collector plate 53 on the battery inner side. As a deterrent when vibration or impact from external pressure applied to the secondary battery 1 adversely affects the fragile portion 53b of the current interrupting structure through the positive electrode current collector plate 53 or the compression portion of the gasket 26 that keeps hermeticity. It becomes.

  The current interrupting structure is interposed in the current path between the wound electrode group 3 and the positive electrode connection terminal 52. For example, the fragile part of the current interrupting structure breaks due to an unexpected situation such as overcharge. However, if it is fixed only at the fragile part or welded part, the fragile part or welded part may break due to external vibration or impact, resulting in loss of sealing performance. There is also a possibility of causing malfunction and quality degradation.

  According to the present embodiment, by fixing the positive electrode internal insulating member 24 on both the inside and outside of the battery, it is possible to suppress the vibration and impact from being applied to the weakened portion 53b and the joint portion 53a of the base portion 53d, and in an unintended situation. Generation | occurrence | production of peeling of the junction part 53a and a fracture | rupture of the weak part 53b can be prevented. Therefore, it is possible to obtain the lithium ion secondary battery 1 having a current blocking structure with increased rigidity against vibration and impact.

  In the present embodiment, the case where the positive electrode terminal component 50 is provided with the current interruption structure has been described, but the negative electrode terminal component 60 may be similarly provided with the current interruption structure.

[Second Embodiment]
Next, a second embodiment will be described below with reference to FIG. In addition, about the component similar to 1st Embodiment, the detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol.

FIG. 16 is a cross-sectional view illustrating a configuration example of a caulking portion in the second embodiment, and corresponds to a portion B in FIG.
What is characteristic in the present embodiment is that the seal member 44 is interposed only on the curved surface portion 42a side of the flange portion 42b.

  The seal member 44 has a ring shape with a rectangular cross section that is circumferentially continuous along a lower surface that is a surface of the flange portion 42b on the curved surface portion 42a side. The seal member 44 is interposed only between the lower surface of the flange portion 42b and the caulking portion 41d. In the lead 41, the upper surface of the flange portion 42b is in contact with the groove bottom of the concave groove 41b and is electrically connected to the diaphragm 42.

  According to the configuration described above, as in the first embodiment, the flange portion 42b of the diaphragm 42 is fixed by caulking, so that the diaphragm 42 can be easily and reliably fixed to the lead 41 and hermetically sealed. As compared with the first embodiment, the caulking load can be reduced, and the assembling work can be facilitated. In addition, the lead 41 can be caulked while confirming that the seal member 44 is disposed at the regular position, and the positional deviation of the seal member 44 can be prevented. Therefore, the reliability of sealing can be further improved.

[Third Embodiment]
Next, a third embodiment will be described below with reference to FIG. In addition, about the component similar to 1st and 2nd embodiment, the detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol.

FIG. 17 is a cross-sectional view illustrating a configuration example of a caulking portion in the third embodiment, and corresponds to a portion B in FIG.
What is characteristic in the present embodiment is that the seal member 45 is interposed only between the flange portion 42b and the groove bottom of the concave groove 41b.

  The seal member 45 has a ring shape with a rectangular cross section that is circumferentially continuous along an upper surface that is a surface opposite to the curved surface portion 42a of the flange portion 42b. The seal member 45 is interposed only between the upper surface of the flange portion 42b and the groove bottom of the concave groove 41b. In the lead 41, the lower surface of the flange portion 42b is in contact with the caulking portion 41d and is electrically connected to the diaphragm 42.

  According to the configuration described above, as in the first and second embodiments, the flange portion 42b of the diaphragm 42 is fixed by caulking, so that the diaphragm 42 is easily and reliably fixed to the lead 41 and hermetically sealed. Can do. Since the seal member 45 is interposed between the flat surfaces of the upper surface of the flange portion 42b and the groove bottom of the concave groove 41b as compared with the second embodiment, the seal member 45 is uniformly pressed and is high. Sealability can be obtained.

  Further, since there is no possibility that the seal member 45 comes into contact with the first inclined surface portion of the diaphragm 42, it is not necessary to increase the accuracy of the dimensional shape and position of the seal member 45, and the manufacturing cost can be reduced and the implementation can be facilitated. .

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 Square secondary battery 2 Battery container 3 Electrode group 4 Lid assembly 5 Power generation element assembly 11 Battery can 11a Opening part 21 Battery cover 22 Positive electrode external insulation member 23 Negative electrode external insulation member 24 Positive electrode internal insulation member 24a Holding part 25 Negative electrode inside Insulating member 26 Gasket 31 Negative electrode plate 31a Negative electrode coated portion 31b Negative electrode uncoated portion 32 Separator 33 Positive electrode plate 33a Positive electrode coated portion 33b Positive electrode uncoated portion 34 Separator 35 Tape 41 Lead 42 Diaphragms 43, 44, 45 Seal member 51 Positive electrode external terminal 52 Positive electrode connection terminal 52a Flat plate portion 53 Positive electrode current collector plate 53a Joint portion 53b Weak portion 61 Negative electrode external terminal 62 Negative electrode connection terminal 63 Negative electrode current collector plate 71 Gas discharge valve 72 Injection port 73 Injection plug

Claims (8)

A prismatic secondary battery having a battery container containing a flat electrode group, a battery lid for sealing the battery container, and a connection terminal inserted into an opening opened in the battery lid,
A lead disposed in the battery container and connected to the connection terminal;
A diaphragm that is connected to the lead and closes the through-hole penetrating the connection terminal, and is deformed by an increase in internal pressure of the battery container;
Have
The rectangular secondary battery, wherein the diaphragm is fixed by caulking to the lead. The diaphragm has a dome-shaped curved surface portion that gradually decreases in diameter as it moves in the axial direction, and a flange portion that expands radially outward from the outer peripheral edge of the curved surface portion,
2. The prismatic secondary battery according to claim 1, wherein the lead includes a caulking portion that is caulked and fixed by sandwiching the flange portion from both axial sides of the diaphragm. The lead is continuously recessed in a flat shape on the flat surface of the lead so that the flange portion is inserted, and the lead is opposed to the outer peripheral end surface of the flange portion at a radially outer position of the groove. An outer peripheral wall that rises,
3. The prismatic secondary battery according to claim 2, wherein the caulking portion is formed by inserting the flange portion into the concave groove and bending the distal end side of the outer peripheral wall portion radially inward.   The prismatic secondary battery according to claim 3, further comprising a sealing member interposed between the flange portion and the caulking portion.   The prismatic secondary battery according to claim 3, further comprising a seal member interposed between the flange portion and a groove bottom of the concave groove.   The square secondary according to claim 3, further comprising a sealing member interposed between the flange portion and the groove bottom of the concave groove and between the flange portion and the caulking portion. battery.   7. The prismatic secondary battery according to claim 4, wherein the caulking portion has a distal end portion bent toward a side closer to the flange portion than a proximal end side of the caulking portion.   2. The current collecting plate according to claim 1, further comprising a current collecting plate that connects between the diaphragm and the electrode group, breaks due to deformation of the diaphragm, and interrupts conduction between the diaphragm and the electrode group. Square rechargeable battery.

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