Secondary battery and secondary battery module

Abstract

To provide a secondary battery and a secondary battery module, in which the airtightness in a terminal part is secured.SOLUTION: A secondary battery in an embodiment includes: an exterior can having a first penetration hole and an exterior can engagement part; an electrode group accommodated in the exterior can and including a positive electrode and a negative electrode; a lead electrically connected to at least one of the positive electrode and the negative electrode; an insulated gasket having an opening part disposed along an inner wall of the first penetration hole; an external terminal having a shaft part disposed in the opening part, with the shaft part electrically connected to the lead, and fixed by caulking to the exterior can through the insulated gasket; and a terminal insulator for insulating the exterior can and the external terminal and disposed between the exterior can and a connection member electrically connectable to the external terminal. The terminal insulator has a first engaged part engaged with the exterior can engagement part, and a second engaged part engaged with a connection member engagement part of the connection member.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] FIELD An embodiment of the present invention relates to a secondary battery and a secondary battery module. [Background technology]

[0002] In recent years, secondary batteries such as lead-acid batteries and nickel-metal hydride batteries have been used as power sources for electric vehicles, hybrid vehicles, electric motorcycles, forklifts, etc. Recently, there has been active development toward the adoption of lithium-ion secondary batteries, which have high energy density, and development is being carried out while taking into consideration factors such as long life and safety.

[0003] When these secondary batteries are used as large-scale, high-capacity power sources, a secondary battery module is used in which multiple secondary batteries are connected in series or in parallel. The multiple secondary batteries are electrically connected to each other via external terminals of the secondary batteries using connecting members such as bus bars.

[0004] In the secondary battery module, a load is applied from the bus bar to the terminal portion of the secondary battery, specifically, the external terminal, due to vibration. In addition, when the secondary battery module is energized, the bus bar thermally expands due to a temperature rise caused by Joule heat, and a load is applied from the bus bar to the external terminal. This load applied to the external terminal loosens the seal portion of the insulating gasket that crimps the external terminal, and there is a problem that the airtightness inside the secondary battery cannot be guaranteed. Furthermore, when a large current is passed through the secondary battery module, it is common to design the bus bar to be thicker in order to suppress the temperature rise caused by Joule heat. However, when the bus bar becomes thicker, the load applied to the external terminal during energization tends to become larger. This makes the problem that the airtightness inside the secondary battery cannot be guaranteed even more pronounced. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-71104 A [Patent Document 2] JP 2012-142298 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a secondary battery and a secondary battery module that ensure airtightness at the terminals. [Means for solving the problem]

[0007] In order to achieve the above object, a secondary battery according to an embodiment of the present invention comprises an outer can having a first through hole and an outer can engaging portion, an electrode group including a positive electrode and a negative electrode housed in the outer can, a lead electrically connected to at least one of the positive electrode and the negative electrode, an insulating gasket having an opening disposed along an inner wall of the first through hole, an external terminal having a shaft portion disposed in the opening, the shaft portion being electrically connected to the lead and being crimped and fixed to the outer can via the insulating gasket, and a terminal insulator that insulates the outer can from the external terminal and is disposed between a connecting member capable of being electrically connected to the external terminal and the outer can. The terminal insulator has a first engaging portion that engages with the outer can engaging portion and a second engaging portion that engages with a connecting member engaging portion of the connecting member. [Brief description of the drawings]

[0008] [Figure 1] 1 is a perspective view illustrating a secondary battery according to a first embodiment; [Diagram 2] 1 is a perspective view showing a secondary battery according to a first embodiment, the secondary battery being disassembled into individual components; [Diagram 3] FIG. 1 is a perspective view illustrating a terminal structure of a secondary battery according to a first embodiment. [Figure 4] 4 is a cross-sectional view of a longitudinal section taken along line XX in FIG. 3, as viewed from the direction of the arrow, in the terminal structure of the secondary battery according to the first embodiment. [Diagram 5]4 is a cross-sectional view of a crimped portion when a vertical cross section taken along line YY in FIG. 3 is viewed from the direction of an arrow in the terminal structure of the secondary battery according to the first embodiment. [Figure 6] FIG. 2 is a schematic plan view of the terminal structure of the secondary battery according to the first embodiment. [Figure 7] FIG. 11 is a perspective view illustrating a terminal structure of a secondary battery according to a second embodiment. [Figure 8] 8 is a cross-sectional view of a crimped portion in a longitudinal section taken along line ZZ in FIG. 7, as viewed from the direction of the arrow, in the terminal structure for a secondary battery according to the second embodiment. [Figure 9] FIG. 13 is a perspective view illustrating a secondary battery module according to a third embodiment. [Figure 10] 10 is a cross-sectional view of a crimped portion when a vertical cross section taken along line WW in FIG. 9 is viewed from the direction of an arrow in the terminal structure of a secondary battery module according to a third embodiment. [Figure 11] FIG. 13 is a perspective view illustrating a secondary battery module according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a secondary battery and a secondary battery module according to embodiments will be described with reference to the drawings.

[0010] (First embodiment) A secondary battery 1 according to a first embodiment will be described with reference to Figs. 1 and 2. Fig. 1 is a perspective view that shows a schematic diagram of the secondary battery according to the first embodiment, and Fig. 2 is a perspective view that shows a schematic diagram of the secondary battery according to the first embodiment in a state where each component is disassembled. As shown in Figs. 1 and 2, the secondary battery 1 includes an outer can 3 and an electrode group 5. The outer can 3 includes an outer can body 4 and a lid member 7. The outer can body 4 has a space therein and is in the shape of a rectangular cylinder with an opening 2 provided on the upper surface. The lid member 7 closes the opening 2. The outer can body 4 and the lid member 7 are formed of a metal such as aluminum, an aluminum alloy, iron, copper, or stainless steel.

[0011] The electrode group 5 is housed inside the exterior can 3. The electrode group 5 is produced by sandwiching a separator (not shown) between the positive electrode 9 and the negative electrode 11, winding them into a spiral shape, and then pressure-molding the whole into a flat shape. The positive electrode 9 has a positive electrode current collector 9a and a positive electrode active material layer (not shown) laminated on one or both sides of the positive electrode current collector 9a. The positive electrode current collector 9a has a positive electrode current collector tab 9b as a portion where the positive electrode active material layer is not applied. On the other hand, the negative electrode 11 has a negative electrode current collector 11a and a negative electrode active material layer (not shown) laminated on one or both sides of the negative electrode current collector 11a. The negative electrode current collector 11a has a negative electrode current collector tab 11b as a portion where the negative electrode active material layer is not applied. Each of these positive electrode current collecting tabs 9b and negative electrode current collecting tabs 11b is clamped by two pairs of clips (backup leads) 34a, 34b arranged inside the outer can 3. The electrode group 5 may have a stack structure produced by alternately stacking a plurality of positive electrodes 9 and a plurality of negative electrodes 11. When using an electrode group 5 with a stack structure, the connection structure with the outer can 3 is changed as appropriate. The electrode group 5 is not limited to a wound type or a stack structure.

[0012] The positive electrode 9 is prepared by applying a slurry containing a positive electrode active material to a positive electrode current collector 9a made of aluminum foil or aluminum alloy foil. Examples of the positive electrode active material include oxides, sulfides, and polymers that can absorb and release lithium ions, but are not limited to these. Preferred positive electrode active materials include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, and lithium iron phosphate.

[0013] The negative electrode 11 is prepared by applying a slurry containing a negative electrode active material to a negative electrode current collector 11a made of aluminum foil, aluminum alloy foil, copper foil, or the like. Examples of the negative electrode active material include, but are not limited to, metal oxides, metal sulfides, metal nitrides, and carbon materials capable of absorbing and releasing lithium ions. A preferred negative electrode active material is a material whose lithium ion absorbing and releasing potential is 0.4 V or more more noble than the metallic lithium potential. Such a negative electrode active material can suppress the alloy reaction between aluminum or an aluminum alloy and metallic lithium. Therefore, such a negative electrode active material enables the use of aluminum or an aluminum alloy for the negative electrode current collector 11a and the negative electrode-related components. Preferred negative electrode active materials include titanium oxide, lithium titanium oxide, niobium titanium oxide, niobium oxide, tungsten oxide, amorphous tin oxide, tin silicon oxide, silicon oxide, and silicon. When a carbon material that absorbs and releases lithium ions is used as the negative electrode active material, it is preferable to use copper foil for the negative electrode current collector 11a. The carbon material used as the negative electrode active material has a lithium ion absorption and release potential of about 0 V relative to the potential of metallic lithium.

[0014] The separator is made of an electrically insulating material, such as cellulose, polyethylene, polypropylene, ethylene-propylene copolymer, or ethylene-butene copolymer.

[0015] Inside the exterior can 3, the electrode group 5 is impregnated with an electrolyte (not shown). The electrolyte is injected from an injection port 13 provided in the cover member 7, and the injection port 13 is closed with a sealing plate 15 after the electrolyte is injected. The electrolyte is a non-aqueous electrolyte prepared by dissolving an electrolyte (e.g., a lithium salt) in a non-aqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone (γ-BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), and 2-methyltetrahydrofuran. The non-aqueous solvent may be used alone or in combination of two or more. Examples of the electrolyte include lithium salts such as lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenic (LiAsF6), and lithium trifluoromethasulfonate (LiCF3SO3). The electrolyte may be used alone or in combination of two or more. The amount of the electrolyte dissolved in the non-aqueous solvent is preferably 0.2 mol / L or more and 3 mol / L or less.

[0016] Furthermore, on the surface of the lid member 7, a gas exhaust valve 16 is formed together with the liquid inlet 13. The liquid inlet 13 and the gas exhaust valve 16 do not have to be provided on the secondary battery 1. Furthermore, a pair of external terminals 17 are attached to the surface of the lid member 7. The external terminals 17 are made of a conductive material such as metal. One of the external terminals 17 is a positive electrode external terminal 17a, and the other is a negative electrode external terminal 17b. The external terminal 17 has a rectangular head 18 and a shaft portion 20 extending downward from the head 18. The shaft portion 20 is inserted into a pair of through holes 19a, 19b provided on the surface of the lid member 7.

[0017] A pair of terminal insulators 21a, 21b are provided between the pair of external terminals 17a, 17b and the cover member 7. The terminal insulator 21 insulates the external terminal 17 from the cover member 7. The terminal structure of the secondary battery according to the first embodiment will be described with reference to Figs. 3 to 5. Fig. 3 is a perspective view that shows a schematic view of the terminal structure of the secondary battery according to the first embodiment. Fig. 4 is a cross-sectional view of the longitudinal section taken along line XX in Fig. 3 as viewed from the direction of the arrow in the terminal structure of the secondary battery according to the first embodiment. Fig. 5 is a cross-sectional view of the crimped portion of the longitudinal section taken along line YY in Fig. 3 as viewed from the direction of the arrow in the terminal structure of the secondary battery according to the first embodiment. 3 to 5, the terminal insulator 21 has a substantially square base portion 24 in which a through hole 22 is formed, a side wall portion 26 rising upward from the four sides of the base portion 24, a first engagement portion 28 extending downward from four corners of the bottom surface of the side wall portion 26, and a second engagement portion 30 extending upward from four corners of the top surface of the side wall portion 26. The first engagement portion 28 engages with an outer can engagement portion 23 provided on the surface of the lid member 7. The second engagement portion 30 is connected to a connection member (not shown) such as a bus bar.

[0018] The terminal insulator 21 is not limited to any material as long as it is insulating, but it is preferable to use a thermoplastic resin. Representative synthetic resins include polypropylene (PP), tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), polyphenylene sulfide (PPS), etc.

[0019] An insulating gasket 25 is disposed on the inner wall of the through hole 22 of the terminal insulator 21. The insulating gasket 25 has a cylindrical tube portion 14 and flange portions 12 formed in a brim shape at both open ends of the tube portion 14. The tube portion 14 is inserted into the through hole 22 of the terminal insulator 21, and the flange portions 12 cover the periphery of the through hole 22 of the terminal insulator 21.

[0020] The shaft portion 20 of the external terminal 17 is inserted into the cylindrical portion 14 of the insulating gasket 25, the through hole 22 of the terminal insulator 21, and the through hole of the cover member 7, and then connected to a pair of leads 27 provided inside the exterior can 3. The leads 27 are made of a conductive material such as metal. As a result, the positive electrode current collector tab 9b and the negative electrode current collector tab 11b of the electrode group 5 are electrically connected to the external terminal 17 via the leads 27. The head 18 of the external terminal 17 is accommodated in a space surrounded by the base portion 24 and the side wall portion 26 of the terminal insulator 21.

[0021] When the shaft portion 20 is pressurized in the axial direction while the position of the head 18 of the external terminal 17 is fixed, the shaft portion 20 expands and deforms. As a result, the shaft portion 20 of the external terminal 17 and the insulating gasket 25 are compressed, and the shaft portion 20 of the external terminal 17 is crimped and fixed to the cover member 7 and the lead 27 via the insulating gasket 25. The external terminal 17 and the cover member 7 are crimped and fixed via the insulating gasket 25, thereby ensuring the insulation and airtightness of the secondary battery 1. When the external terminal 17 and the cover member 7 are crimped and fixed, the flange portion 12 is fixed between the head 18 of the external terminal 17 and the cover member 7 while filling the gap with the seat portion 24 of the terminal insulator 21. As a result, the gap between the insulating gasket 25 and the terminal insulator 21 disappears, and a structure that prevents short circuits due to migration is possible.

[0022] A pair of insulating guards 29 and an internal insulating member 31 are disposed inside the exterior can 3. The positive electrode side lead, which is one of the leads 27, and the positive electrode current collector tab 9b are each prevented from contacting the exterior can 3 by the corresponding one of the insulating guards 29, and are electrically insulated from the exterior can 3. The negative electrode side lead, which is one of the leads 27, and the negative electrode current collector tab 11b are each prevented from contacting the exterior can 3 by the corresponding one of the insulating guards 29, and are electrically insulated from the exterior can 3. Each of the insulating guards 29 is fixed to the electrode group 5 by an insulating tape 33. The internal insulating member 31 is disposed between the electrode group 5 and the lid member 7. The positive electrode current collector tab 9b, the negative electrode current collector tab 11b, and the lead 27 are electrically insulated from the lid member 7 by the internal insulating member 31.

[0023] In the first embodiment, the first engagement portion 28 of the terminal insulator 21 is a convex portion, and the outer can engagement portion 23 is a concave portion. The convex portion of the first engagement portion 28 and the concave portion of the outer can engagement portion 23 are engaged with each other. As a result, when the external terminal 17 is connected to the bus bar via the second engagement portion 30 and the external terminal 17 receives a load from the bus bar, the load can be distributed not only to the insulating gasket 25 but also to the terminal insulator 21. The first engagement portion 28 and the outer can engagement portion 23 are engaged with each other at the four corners of the bottom surface of the side wall portion 26, so that the load from the bus bar can be evenly received by the terminal insulator 21. When the first engagement portion 28 and the outer can engagement portion 23 are not engaged with each other, the load received by the external terminal 17 from the bus bar is received only by the insulating gasket 25, and the sealing property of the insulating gasket 25 is reduced. As a result, a gap is generated between the external terminal 17 and the lid member 7 at the portion where the external terminal 17 and the lid member 7 are crimped and fixed via the insulating gasket 25, and the airtightness of the secondary battery 1 is not ensured. Furthermore, the engagement between the convex portion of the first engagement portion 28 and the concave portion of the outer can engagement portion 23 suppresses the terminal insulator 21 from being misaligned from the cover member 7. This ensures the insulation between the external terminal 17 and the cover member 7.

[0024] The depth of the recess of the outer can engaging portion 23 is preferably ⅓ or more and ⅔ or less of the thickness of the lid member 7. If the depth of the recess of the outer can engaging portion 23 is less than ⅓ of the thickness of the lid member 7, the engagement between the first engaging portion 28 and the outer can engaging portion 23 is insufficient. This reduces the effect of the terminal insulator 21 receiving the load that the external terminal 17 receives from the bus bar. Furthermore, if the depth of the recess of the outer can engaging portion 23 is deeper than ⅔ of the thickness of the lid member 7, the strength of the lid member 7 is weakened.

[0025] The engagement position 38 between the first engagement portion 28 and the outer can engagement portion 23 will be described with reference to Fig. 6. Fig. 6 is a schematic plan view of the terminal structure of the secondary battery according to the first embodiment. As shown in Fig. 6, it is preferable that the linear distance I from the center of the seat portion 24 to the center of the engagement position 38 is 1 / 3 or more and 2 / 3 or less in the longitudinal direction of the side wall portion 26. If the linear distance I is less than 1 / 3 of the longitudinal direction of the side wall portion 26, the formation of the first engagement portion 28 may cause deformation of the seat portion 24. If the linear distance I is longer than 2 / 3 of the longitudinal direction of the side wall portion 26, the terminal insulator 21 may be deformed by the load received from the bus bar.

[0026] In the first embodiment, the first engagement portion 28 is a cylindrical convex portion, and the outer can engagement portion 23 is a cylindrical concave portion, but the shapes are not particularly limited as long as the first engagement portion 28 and the outer can engagement portion 23 can engage with each other. The first engagement portion 28 may be a concave portion, and the outer can engagement portion 23 may be a convex portion, and the shapes are not particularly limited as long as the first engagement portion 28 and the outer can engagement portion 23 can engage with each other. In addition, it is sufficient that one or more first engagement portions 28 and one or more outer can engagement portions 23 are provided. Furthermore, the planar shapes of the seat portion 24 and the side wall portion 26 of the terminal insulator 21 are not limited to a substantially square shape, and may be rectangular, circular, or the like.

[0027] In the first embodiment, the second engagement portion 30 is a cylindrical protrusion, but the shape is not limited thereto. The second engagement portion 30 may be a protrusion and may have a different shape from the first engagement portion 28. In addition, one or more second engagement portions 30 may be provided. Furthermore, from the viewpoint of reducing the load from the bus bar to the external terminal 17, the second engagement portion 30 is preferably provided on the same axial line as the first engagement portion 28, but the position at which the second engagement portion 30 is provided is not limited thereto. The second engagement portion 30 may be provided on any one of the upper surfaces of the side wall portion 26, and may be provided on the surface opposite to the surface on which the first engagement portion 28 is provided.

[0028] According to the present embodiment, exterior can engagement portion 23 provided on the surface of lid member 7 engages with first engagement portion 28 of terminal insulator 21. As a result, external terminal 17 is connected to the bus bar via second engagement portion 30, and when external terminal 17 receives a load from the bus bar, the load can be distributed not only to insulating gasket 25 but also to terminal insulator 21. Therefore, even when external terminal 17 receives a load from the bus bar, the sealing property of insulating gasket 25 is ensured, so that a secondary battery that ensures airtightness at the terminal portion can be provided.

[0029] Furthermore, according to this embodiment, the load that the external terminal 17 receives from the bus bar can be distributed not only to the insulating gasket 25 but also to the terminal insulator 21, thereby improving the vibration resistance of the secondary battery 1. In addition, the resistance of the bus bar to thermal expansion while the secondary battery 1 is energized is also improved, making it possible to design the bus bar to be thicker. This makes it possible to pass a large current through the secondary battery 1.

[0030] Second Embodiment The terminal structure of the secondary battery 1 according to the second embodiment will be described with reference to Figs. 7 and 8. Fig. 7 is a perspective view showing the terminal structure of the secondary battery 1 according to the second embodiment. Fig. 8 is a cross-sectional view of a crimped portion in the terminal structure of the secondary battery 1 according to the second embodiment, taken along line ZZ in Fig. 7, as seen from the direction of the arrow. The second embodiment differs from the first embodiment in that the terminal insulator 21 is changed to a terminal insulator 41. Since the second embodiment is the same as the first embodiment except for the terminal insulator 41, the same parts are denoted by the same reference numerals and detailed description thereof will be omitted.

[0031] 7 and 8, the terminal insulator 41 has a first engagement portion 42 extending downward from the bottom surface of the side wall portion 26 and a second engagement portion 44 extending upward from the upper surface of the side wall portion 26. In the second embodiment, the first engagement portion 42 is a protruding portion having a rectangular prism shape, and the outer can engagement portion 46 is a recessed portion having a rectangular prism shape. The second engagement portion 44 is a protruding portion having a rectangular prism shape. Here, the corners of the protruding portion of the second engagement portion 44 may be chamfered or formed into an arc shape.

[0032] According to the present embodiment, similarly to the first embodiment, exterior can engagement portion 46 provided on the surface of lid member 7 engages with first engagement portion 42 of terminal insulator 41. As a result, external terminal 17 is connected to the bus bar via second engagement portion 44, and when external terminal 17 receives a load from the bus bar, the load can be distributed not only to insulating gasket 25 but also to terminal insulator 41. Therefore, even when external terminal 17 receives a load from the bus bar, the sealing property of insulating gasket 25 is ensured, so that a secondary battery 1 that ensures airtightness at the terminal portion can be provided.

[0033] Furthermore, according to this embodiment, the load that the external terminal 17 receives from the bus bar can be distributed not only to the insulating gasket 25 but also to the terminal insulator 41, thereby improving the vibration resistance of the secondary battery 1. In addition, the resistance to thermal expansion of the bus bar while the secondary battery 1 is energized is also improved, making it possible to design the bus bar to be thicker. This makes it possible to pass a large current through the secondary battery 1.

[0034] (Third embodiment) A secondary battery module 51 according to a third embodiment will be described with reference to FIGS. 9 and 10. FIG. 9 is a perspective view showing a secondary battery module according to the third embodiment, which includes a plurality of secondary batteries 1 according to the first embodiment. FIG. 10 is a cross-sectional view of a crimped portion when a vertical cross section taken along line WW in FIG. 9 is viewed from the direction of the arrow in a terminal structure of a secondary battery module according to the third embodiment. The secondary battery module 51 includes a connection member 53 such as a bus bar for electrically connecting the external terminal 17. The connection member 53 is formed of a conductive material such as metal, and has a connection member engagement portion 54 that engages with the second engagement portion 30 of the terminal insulator 21. The connection member engagement portion 54 is a through hole, and the second engagement portion 30 of the terminal insulator 21 is inserted into the connection member engagement portion 54. This can suppress misalignment of the connection member 53 with respect to the terminal insulator 21.

[0035] After the second engagement portion 30 is inserted into the connection member engagement portion 54, the head 18 of the external terminal 17 and the connection member 53 are welded via a pair of welds 57. Examples of welding methods include laser welding, resistance welding, and ultrasonic welding. As a result, the multiple secondary batteries 1 are electrically connected by the connection member 53 and connected in series. Note that the connection of the secondary batteries 1 is not limited to series, and parallel connection is also possible. In addition, a pair of secondary batteries 1 of the first embodiment may be connected, or a secondary battery 1 and another secondary battery different from the secondary battery 1 may be connected.

[0036] The second engaging portion 30 is inserted into the connecting member engaging portion 54, and the second engaging portion 30 may be fixed to the connecting member engaging portion 54 by press-fitting. This enhances the effect of suppressing misalignment of the connecting member 53 with respect to the terminal insulator 21. Furthermore, since the second engaging portion 30 and the connecting member engaging portion 54 are fixed, the load that the external terminal 17 receives from the connecting member 53 can also be received by the engaging portion between the second engaging portion 30 and the connecting member engaging portion 54. As a result, the load that the external terminal 17 receives from the connecting member 53 is received by both the engaging portion between the exterior can engaging portion 23 and the first engaging portion 28 and the engaging portion between the second engaging portion 30 and the connecting member engaging portion 54. This enhances the effect of suppressing the load on the insulating gasket 25.

[0037] The second engaging portion 30 may be fixed to the connecting member engaging portion 54 by heat crimping. When the second engaging portion 30 is fixed to the connecting member engaging portion 54 by heat crimping, as shown in FIG. 10, the protruding portion 55 of the second engaging portion 30 protruding from the connecting member engaging portion 54 is melted by heat. The second engaging portion 30 is deformed by heat and fixed to the inner wall of the connecting member engaging portion 54. The terminal insulator 21 is a thermoplastic resin, and heat near the melting point of the thermoplastic resin used is applied to the protruding portion 55. The height P from the upper surface of the side wall portion 26 of the second engaging portion 30 to the upper surface of the connecting member 53 after heat crimping is preferably 1.1 to 2.6 times the thickness of the connecting member 53. When the height P is less than 1.1 times the thickness of the connecting member 53, the rigidity of the second engaging portion 30 is high, but the head 18 of the external terminal 17 needs to be thinned, and the rigidity of the external terminal 17 is reduced. Furthermore, if the height P is greater than 2.6 relative to the thickness of the connecting member 53, the second engagement portion 30 will be deformed by the load received from the connecting member 53, and the effect of the terminal insulator 21 receiving the load received by the external terminal 17 from the connecting member 53 will be reduced.

[0038] Further, the second engagement portion 30 is provided excluding the imaginary line between the pair of welded portions 57. The imaginary line is a straight line Q connecting the centers of the welded portions 57 on the pair of external terminals 17, as shown in Fig. 9. By providing the second engagement portion 30 so as not to come into contact with the straight line Q, an increase in electrical resistance between the external terminals 17 during current flow is suppressed.

[0039] According to this embodiment, not only do the exterior can engaging portion 23 provided on the surface of the lid member 7 engage with the first engaging portion 28 of the terminal insulator 21, but the second engaging portion 30 also engages with the connecting member engaging portion 54. As a result, when the external terminal 17 receives a load from the connecting member 53, the load can be dispersed not only by the insulating gasket 25 but also by both the engaging portion between the exterior can engaging portion 23 and the first engaging portion 28 and the engaging portion between the second engaging portion 30 and the connecting member engaging portion 54. Therefore, even when the external terminal 17 receives a load from the connecting member 53, the sealing property of the insulating gasket 25 is ensured, so that the airtightness of the secondary battery 1 used in the secondary battery module 51 can be ensured.

[0040] Furthermore, according to this embodiment, the load that the external terminal 17 receives from the connection member 53 can be distributed not only by the insulating gasket 25 but also by both the engagement portion between the outer can engagement portion 23 and the first engagement portion 28 and the engagement portion between the second engagement portion 30 and the connection member engagement portion 54, so that the vibration resistance of the secondary battery 1 used in the secondary battery module 51 is increased. In addition, the resistance of the connection member 53 to thermal expansion during current flow of the secondary battery 1 used in the secondary battery module 51 is also increased, so that it is possible to design the connection member 53 to be thicker. Therefore, it is possible to pass a large current through the secondary battery 1 used in the secondary battery module 51.

[0041] (Fourth embodiment) A secondary battery module 61 according to a fourth embodiment will be described with reference to Fig. 11. Fig. 11 is a perspective view showing a schematic view of a secondary battery module according to the fourth embodiment. The fourth embodiment differs from the third embodiment in that the terminal insulator 21 is changed to the configuration of the terminal insulator 41 according to the second embodiment. Since the fourth embodiment is the same as the third embodiment except for the terminal insulator 41, the same parts are denoted by the same reference numerals and detailed description thereof will be omitted.

[0042] The second engagement portion 44 of the terminal insulator 41 is inserted into the connection member engagement portion 54, and the second engagement portion 44 is preferably fixed to the connection member engagement portion 54 by press-fitting or heat caulking.

[0043] According to this embodiment, similarly to the third embodiment, not only do the exterior can engaging portion 46 provided on the surface of the lid member 7 engage with the first engaging portion 42, but also the second engaging portion 44 engages with the connecting member engaging portion 54. As a result, when the external terminal 17 receives a load from the connecting member 53, the load can be dispersed not only by the insulating gasket 25 but also by both the engaging portion between the exterior can engaging portion 46 and the first engaging portion 42 and the engaging portion between the second engaging portion 44 and the connecting member engaging portion 54. Therefore, even when the external terminal 17 receives a load from the connecting member 53, the sealing property of the insulating gasket 25 is ensured, and therefore the airtightness of the secondary battery 1 used in the secondary battery module 61 can be ensured.

[0044] Furthermore, according to this embodiment, the load that the external terminal 17 receives from the connection member 53 can be distributed not only by the insulating gasket 25 but also by both the engagement portion between the outer can engagement portion 46 and the first engagement portion 42 and the engagement portion between the second engagement portion 44 and the connection member engagement portion 54, so that the vibration resistance of the secondary battery 1 used in the secondary battery module 61 is increased. In addition, the resistance of the connection member 53 to thermal expansion during current flow of the secondary battery 1 used in the secondary battery module 61 is also increased, so that it is possible to design the connection member 53 to be thicker. Therefore, it is possible to pass a large current through the secondary battery 1 used in the secondary battery module 61.

[0045] According to at least one of the embodiments of the secondary battery module described above, the outer can engaging portion engages with the first engaging portion, and the second engaging portion engages with the connecting member engaging portion. This allows the load that the external terminal receives from the connecting member to be distributed between the engaging portion between the outer can engaging portion and the first engaging portion and the engaging portion between the second engaging portion and the connecting member engaging portion. Therefore, even if the external terminal receives a load from the connecting member, the sealing property of the insulating gasket is guaranteed, so that the airtightness of the secondary battery used in the secondary battery module can be guaranteed. In addition, a secondary battery that is highly resistant to vibration and capable of passing a large current can be provided.

[0046] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0047] 1...secondary battery, 2...opening, 3...outer can, 4...outer can body, 5...electrode group, 7...lid member, 9...positive electrode, 9a...positive electrode current collector, 9b...positive electrode current collector tab, 11...negative electrode, 11a...negative electrode current collector, 11b...negative electrode current collector tab, 12...flange portion, 13...filling port, 14...tubular portion, 15...sealing plate, 16...gas exhaust valve, 17a, 17b...external terminal, 18...head, 20...shaft portion, 21a, b...terminal insulator, 22...through hole, 23...outer can engagement portion, 24 ...base portion, 25...insulating gasket, 26...side wall portion, 27...lead, 28...first engagement portion, 29...insulating guard, 30...second engagement portion, 31...internal insulating member, 34...backup lead, 38...engagement position, 41...terminal insulator, 42...first engagement portion, 44...second engagement portion, 46...outer can engagement portion, 51...secondary battery module, 53...connecting member, 54...connecting member engagement portion, 55...protrusion, 57...welded portion, 61...secondary battery module.

Claims

1. an outer can having a first through hole and an outer can engagement portion; an electrode group housed in the outer can and including a positive electrode and a negative electrode; a lead electrically connected to at least one of the positive electrode and the negative electrode; an insulating gasket having an opening disposed along an inner wall of the first through hole; an external terminal having a shaft portion disposed in the opening, the shaft portion being electrically connected to the lead, and being crimped and fixed to the outer can via the insulating gasket; a terminal insulator that insulates the outer can from the external terminal and is disposed between a connection member that can be electrically connected to the external terminal and the outer can, The terminal insulator is a secondary battery having a first engagement portion that engages with the outer can engagement portion, and a second engagement portion that engages with the connection member engagement portion of the connection member.

2. The secondary battery according to claim 1 , wherein the outer can engaging portion is a recess, and the first engaging portion is a first protrusion.

3. The secondary battery according to claim 1 , wherein the second engagement portion is a second protrusion, and the second protrusion is provided on a surface opposite to a surface on which the first engagement portion is provided.

4. The outer can includes an outer can body having an opening; a cover member that covers the opening and has the recessed portion provided therein; 3. The secondary battery according to claim 2, wherein the depth of the recess from the surface of the lid member is equal to or greater than 1 / 3 and equal to or less than 2 / 3 of the thickness of the lid member.

5. the external terminal has a virtual line that can be connected to another external terminal via the connection member; The secondary battery according to claim 3 , wherein the second protrusion is provided at a position other than the imaginary line.

6. The secondary battery according to any one of claims 1 to 5, a secondary battery module comprising the connection member electrically connected to the external terminal;

7. The secondary battery according to claim 3 ; the connecting member electrically connected to the external terminal, The connection member engagement portion has a second through hole, The second protrusion is disposed in the second through hole of the secondary battery module.

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