Manufacturing method of secondary battery and secondary battery

Abstract

To more preferably perform welding of a lid member.SOLUTION: In a secondary battery 1, an opening part 50 is sealed by welding a lid member 22 fitted to the opening part 50 in a state where it is inserted into the opening part 50 of a case 20 housing an electrode body. In the lid member 22, an insulation part 55 of an electrode terminal 38 facing an outside of the case 20 is provided. Also, in a peripheral wall 60 of the case 20 forming the opening part 50, a notch part 61 is provided at a position that becomes a peripheral region α1 of the insulation part 55 in a state where the lid member 22 is fitted. In addition, by applying a laser beam L to the opening part 50 and a fitting part 51 of the lid member 22 from an insertion direction of the lid member 22 against the opening part 50, a region other than the peripheral region α1 is welded. Then, in the peripheral region α1, by applying the laser beam L at an angle θ inclined to the insertion direction of the lid member 22 to a boundary part β between an outer peripheral surface 22sb of the lid member 22 exposed into the notch part 61 and an end surface 61s of the notch part 61, the welding is performed.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a secondary battery and a secondary battery. [Background technology]

[0002] Conventionally, there is a secondary battery in which an opening of a case that houses an electrode body is sealed by welding a lid member to the opening. For example, Patent Document 1 describes a method of welding the lid member by irradiating a laser beam from the insertion direction of the lid member to the opening and the fitting part of the lid member while the lid member is inserted into the opening and fitted to the opening. By adopting such a so-called vertical welding method, the lid member can be efficiently welded.

[0003] In the secondary battery described in Patent Document 1, the cover member is provided with an insulating portion for the electrode terminal facing the outside of the case. Furthermore, the cover member has a recessed portion recessed into its outer surface near the insulating portion. This forms a space between the welded portion and the insulating portion, making it difficult for the insulating portion formed of resin to be damaged by the plume generated by heat during welding, that is, the smoke of evaporated metal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-10887 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, there is a problem in that it is difficult to appropriately design a space capable of effectively inhibiting the heat propagation during welding. [Means for solving the problem]

[0006] A method for producing a secondary battery that solves the above problems and various aspects of the secondary battery will be described below. Aspect 1 is a method for manufacturing a secondary battery in which a case that houses an electrode body is inserted into an opening and a lid member that fits into the opening is welded to seal the opening, and the lid member is provided with an insulating portion of an electrode terminal that faces outside the case, and a cutout is provided in a peripheral wall of the case that forms the opening at a position that will become the peripheral region of the insulating portion when the lid member is fitted, and the welding is performed other than the peripheral region by irradiating the opening and the fitting portion of the lid member from the insertion direction of the lid member into the opening with laser light, and the welding of the peripheral region is performed by irradiating the laser light to a boundary portion between the outer peripheral surface of the lid member exposed in the cutout and an end face of the cutout at an angle oblique to the insertion direction of the lid member.

[0007] According to the above method, when welding the peripheral area of ​​the insulating part, the irradiated laser light is less likely to be reflected toward the insulating part of the electrode terminal protruding outside the case. Furthermore, the plume rising from the welded part is less likely to be directed toward the outer surface of the lid member on which the insulating part is provided. This makes it possible to more effectively weld the lid member while protecting the insulating part of the electrode terminal provided on the lid member.

[0008] A second aspect is a method for manufacturing a secondary battery of the first aspect, wherein the cover member has a rectangular planar shape and is inserted into the opening, and the cutout portion is provided in a position aligned with the insulating portion in the short direction of the cover member fitted into the opening.

[0009] According to the above method, for secondary battery cases having a flat, roughly square box-like outer shape that is often used for battery collector cells, etc., a cover member can be more suitably welded to an opening having the same rectangular opening shape as the planar shape of the cover member.

[0010] Aspect 3 is a method for manufacturing a secondary battery of aspect 2, comprising: a first welding step of performing the welding other than the peripheral region using a laser irradiation unit arranged above the lid member; and a second welding step of performing the welding of the peripheral region using a pair of the laser irradiation units arranged at a first lateral position and a second lateral position above the case that sandwich the lid member in the short side direction.

[0011] According to the above method, the effect of heat caused by irradiation with laser light can be suppressed, and the insulating portion of the electrode terminal provided on the cover member can be appropriately protected, while the cover member can be efficiently welded to the opening of the case with a simple configuration.

[0012] A fourth aspect is the method for manufacturing a secondary battery according to any one of the first to third aspects, wherein, when performing the welding of the peripheral region, an inert gas is sprayed onto the peripheral region from above the case on the insulating portion side.

[0013] According to the above method, it is possible to prevent the plume rising from the welding portion from approaching the insulating portion of the electrode terminal provided on the lid member. In particular, when welding the peripheral area, the laser irradiation unit is not located above the lid member. Therefore, the inert gas can be efficiently sprayed from the insulating portion side to the peripheral area of ​​the insulating portion to be welded.

[0014] Aspect 5 is a method for manufacturing a secondary battery according to any one of Aspects 1 to 4, in which a corner between the outer peripheral surface of the lid member exposed in the cutout portion and the outer surface of the lid member from which the insulating portion protrudes is not melted.

[0015] According to the above method, the corner portion configured as the non-melted portion serves as a shielding wall, which makes it even more difficult for the laser light reflected from the welded portion or the plume rising from the welded portion to be directed toward the insulating portion of the electrode terminal provided on the cover member.

[0016] Aspect 6 is a method for manufacturing a secondary battery in which a case that houses an electrode body is inserted into an opening and a lid member that fits into the opening is welded to seal the opening, and the lid member is provided with an insulating portion of the electrode terminal that faces outside the case, and the peripheral wall of the case that forms the opening is provided with an extension portion that extends in the insertion direction of the lid member at a position that will become the peripheral region of the insulating portion when the lid member is fitted, and the welding of the peripheral region is performed by irradiating the opening and the fitting portion of the lid member from the insertion direction of the lid member into the opening with laser light, and the welding of the peripheral region is performed by irradiating the outer surface of a portion of the case having the extension portion at an angle inclined with respect to the insertion direction of the lid member to perform penetration welding between the case and the lid member.

[0017] According to the above method, when welding the peripheral area of ​​the insulating part, the irradiated laser light is less likely to be reflected toward the insulating part of the electrode terminal protruding outside the case. Furthermore, the plume rising from the welded part is less likely to be directed toward the outer surface of the lid member on which the insulating part is provided. This makes it possible to more effectively weld the lid member while protecting the insulating part of the electrode terminal provided on the lid member.

[0018] Aspect 7 is a method for manufacturing a secondary battery of aspect 6, wherein the cover member has a rectangular planar shape and is inserted into the opening, and the extension portion is provided in a position aligned with the insulating portion in the short direction of the cover member fitted into the opening.

[0019] According to the above method, for secondary battery cases having a flat, roughly square box-like outer shape that is often used for battery collector cells, etc., a cover member can be more suitably welded to an opening having the same rectangular opening shape as the planar shape of the cover member.

[0020] Aspect 8 is a method for manufacturing a secondary battery of aspect 7, comprising: a first welding step of performing the welding other than the peripheral region using a laser irradiation unit arranged above the lid member; and a second welding step of performing the welding of the peripheral region using a pair of the laser irradiation units arranged at a first lateral position and a second lateral position above the case that sandwich the lid member in the short side direction.

[0021] According to the above method, it is possible to efficiently weld the cover member to the opening of the case with a simple configuration while suppressing the effects of heat caused by irradiation with laser light and properly protecting the insulating portion of the electrode terminal provided on the cover member.

[0022] A ninth aspect is the method for manufacturing a secondary battery according to any one of the sixth to eighth aspects, wherein, when performing the welding of the peripheral region, an inert gas is sprayed onto the peripheral region from above the outside of the case.

[0023] According to the above method, it is possible to prevent the plume rising from the welding portion from approaching the insulating portion of the electrode terminal provided on the lid member. In particular, when welding the peripheral area, the laser irradiation unit is not located above the lid member. Therefore, the inert gas can be efficiently sprayed from above the outside of the case to the peripheral area of ​​the insulating portion to be welded.

[0024] Aspect 10 is the method for manufacturing a secondary battery according to any one of Aspects 6 to 8, in which the laser light irradiated to the peripheral region penetrates the case and is irradiated toward the insulating portion in the thickness direction of the lid member. This method makes it possible to prevent the penetrating laser light from being shifted from the lid member to enter the inside of the case and being irradiated to the electrode body.

[0025] Aspect 11 is a secondary battery comprising a cover member welded to an opening of a case that houses an electrode body while being inserted into the opening, the cover member having an insulating portion of an electrode terminal that faces the outside of the case, and a peripheral wall of the case that forms the opening has a notch at a position that is the peripheral area of ​​the insulating portion, and the secondary battery has a molten portion at a boundary between an outer circumferential surface of the cover member exposed in the notch and an end face of the notch, and a non-molten portion at a corner between the outer circumferential surface of the cover member exposed in the notch and an outer surface of the cover member from which the insulating portion protrudes.

[0026] According to the above configuration, when welding the peripheral area of ​​the insulating part, the irradiated laser light is less likely to be reflected toward the insulating part of the electrode terminal protruding outside the case. Furthermore, the plume rising from the welded part is less likely to be directed toward the outer surface of the lid member on which the insulating part is provided. This makes it possible to more effectively weld the lid member while protecting the insulating part of the electrode terminal provided on the lid member.

[0027] A twelfth aspect is a secondary battery comprising a cover member inserted into an opening of a case that contains an electrode body and welded to the opening, the cover member having an insulating portion for an electrode terminal that faces the outside of the case, and a peripheral wall of the case that forms the opening has an extension portion that extends in the insertion direction of the cover member at a position that becomes the peripheral area of ​​the insulating portion, and a molten portion is provided on the outer surface of the portion of the case that has the extension portion.

[0028] According to the above configuration, when welding the peripheral area of ​​the insulating part, the irradiated laser light is less likely to be reflected toward the insulating part of the electrode terminal protruding outside the case. Furthermore, the plume rising from the welded part is less likely to be directed toward the outer surface of the lid member on which the insulating part is provided. This makes it possible to more effectively weld the lid member while protecting the insulating part of the electrode terminal provided on the lid member. Effect of the Invention

[0029] According to the present invention, the lid member can be more suitably welded. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a perspective view of a secondary battery. [Diagram 2] FIG. 2 is an exploded view of the electrode assembly. [Diagram 3] FIG. 3 is a side view of the secondary battery. [Figure 4] FIG. 4 is an explanatory diagram of a process for welding a cover member fitted into an opening of a case by irradiation with laser light. [Diagram 5] FIG. 5 is a plan view of the cover member fitted into the opening of the case of the first embodiment. [Figure 6] FIG. 6 is a side view of the case in the embodiment with the lid member fitted into the opening. [Figure 7] FIG. 7 is an enlarged view of the vicinity of a cutout portion provided in the peripheral region of the insulating member of the embodiment. [Figure 8] FIG. 8 is a cross-sectional view of the vicinity of the cutout portion of the embodiment. [Figure 9] FIG. 9 is an explanatory diagram of laser welding in the peripheral region of the insulating member of the embodiment. [Figure 10] FIG. 10 is an enlarged view of the vicinity of the notch after laser welding in this embodiment. [Figure 11] FIG. 11 is an explanatory diagram of a reference example in which "vertical" laser welding is performed around the entire periphery of the cover member. [Figure 12] FIG. 12 is an explanatory diagram of a case where "corner welding" is performed on a cutout portion provided in the peripheral region of the embodiment. [Figure 13] FIG. 13 is an explanatory diagram of a first welding step in which "vertical" laser welding is performed on the non-peripheral region in this embodiment. [Figure 14] FIG. 14 is an explanatory diagram of a second welding step in which "corner welding" is performed on the peripheral region in this embodiment. [Figure 15] FIG. 15 is an explanatory diagram of a reference example in which "corner welding" is performed around the entire periphery of a cover member. [Figure 16]FIG. 16 is a plan view of the cover member fitted into the opening of the case of the second embodiment. [Figure 17] FIG. 17 is a side view of the case in the embodiment with the lid member fitted into the opening. [Figure 18] FIG. 18 is an enlarged view of the vicinity of a cutout portion provided in the peripheral region of the insulating member of the embodiment. [Figure 19] FIG. 19 is a cross-sectional view of the vicinity of the cutout portion of the same embodiment. [Figure 20] FIG. 20 is an explanatory diagram of laser welding in the peripheral region of the insulating member of the same embodiment. [Figure 21] FIG. 21 is an enlarged view of the vicinity of the notch after laser welding in this embodiment. [Figure 22] FIG. 22 is an explanatory diagram of a case where "corner welding" is performed on a cutout portion provided in the peripheral region of the same embodiment. [Figure 23] FIG. 23 is an explanatory diagram of a second welding step in which "corner welding" is performed on the peripheral region in this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] (First embodiment) Hereinafter, a first embodiment of a method for manufacturing a secondary battery and a secondary battery will be described with reference to FIGS.

[0032] (Lithium-ion secondary battery) 1, the secondary battery 1 includes an electrode assembly 10 in which a positive electrode 3, a negative electrode 4, and a separator 5 are integrated, and a case 20 that houses the electrode assembly 10. The secondary battery 1 of this embodiment has a configuration as a lithium ion secondary battery in which the electrode assembly 10 in the case 20 is impregnated with a non-aqueous electrolyte solution (not shown).

[0033] More specifically, in the secondary battery 1 of this embodiment, the positive electrode 3, the negative electrode 4, and the separator 5 are laminated with a sheet-like outer shape. Then, by winding up the laminate of the positive electrode 3, the negative electrode 4, and the separator 5, an electrode body 10 is formed in which the positive and negative electrodes and the separators 5 are alternately arranged in the radial direction with the separator 5 sandwiched between the positive electrode 3 and the negative electrode 4.

[0034] The case 20 of this embodiment includes a case body 21 having a flat, substantially rectangular box shape, and a lid member 22 that closes an open end 21x of the case body 21. The electrode body 10 of this embodiment has a flat outer shape that corresponds to the box shape of the case 20.

[0035] (Electrode sheet and electrode body) More specifically, as shown in Fig. 2, in the secondary battery 1 of this embodiment, the positive electrode 3 and the negative electrode 4 are each configured as an electrode sheet 35 including a current collector foil 31 having a sheet-like outer shape and an electrode active material layer 32 laminated on the current collector foil 31. Specifically, the electrode sheet 35P for the positive electrode 3 is formed by laminating a positive electrode active material layer 32P containing a lithium transition metal oxide as a positive electrode active material on a current collector foil 31P as a base material made of aluminum or the like. The electrode sheet 35N for the negative electrode 4 is formed by laminating a negative electrode active material layer 32N containing a carbon-based material as a negative electrode active material on a current collector foil 31N as a base material made of copper or the like.

[0036] Furthermore, in the secondary battery 1 of this embodiment, the positive and negative electrode sheets 35P, 35N are each shaped into a belt-like shape. The electrode body 10 of this embodiment has a configuration as a wound body in which the positive and negative electrode sheets 35P, 35N, which are stacked with the separator 5 sandwiched therebetween, are wound around a winding axis 10x extending in the width direction of the belt-like shape (the left-right direction in FIG. 2).

[0037] 2, the separator 5 and each electrode sheet 35 are wound in such a manner that the electrode sheet 35P constituting the positive electrode 3 is wound inward. However, this figure is one example showing the structure of the electrode body 10, and the separator 5 and each electrode sheet 35 may be wound in such a manner that the electrode sheet 35N constituting the negative electrode 4 is wound inward. This determines whether the electrode sheet 35 arranged on the outermost shell of the electrode body 10 is the electrode sheet 35P constituting the positive electrode 3 or the electrode sheet 35N constituting the negative electrode 4.

[0038] 1 to 3, the cover member 22 of the case 20 is provided with a positive electrode terminal 38P and a negative electrode terminal 38N that protrude to the outside of the case 20. Furthermore, each electrode sheet 35 has an uncoated portion 39 in which the electrode active material layer 32 is not formed on the current collector foil 31. The secondary battery 1 of this embodiment is configured such that, by utilizing these uncoated portions 39, the electrode sheet 35P constituting the positive electrode 3 and the positive electrode terminal 38P are electrically connected, and the electrode sheet 35N constituting the negative electrode 4 and the negative electrode terminal 38N are electrically connected.

[0039] Specifically, the electrode body 10 of this embodiment is housed in the case 20 with its winding axis 10x aligned along the longitudinal direction (left-right direction in FIG. 1) of the cover member 22, which is an elongated, generally rectangular plate. Furthermore, in this state, an uncoated portion 39P of an electrode sheet 35P constituting the positive electrode 3 is connected to a positive electrode terminal 38P via a connecting member 40P. Similarly, an uncoated portion 39N of an electrode sheet 35N constituting the negative electrode 4 is connected to a negative electrode terminal 38N via a connecting member 40N.

[0040] Furthermore, an electrolyte solution 45 is injected into the case 20. That is, the electrolyte solution 45 of the secondary battery 1 having a configuration as a lithium ion secondary battery is one in which a lithium salt serving as a supporting salt is dissolved in an organic solvent. Thus, the secondary battery 1 of this embodiment is configured such that the electrode body 10 sealed in the case 20 is impregnated with the electrolyte solution 45.

[0041] (Case opening and cover) 1 and 3, in the secondary battery 1 of this embodiment, the opening 50 of the case 20 formed by the opening end 21x of the case body 21 has a rectangular opening shape facing upward (upper side in Figs. 1 and 3). Furthermore, the lid member 22 of this embodiment also has a rectangular planar shape that is approximately the same as the opening shape of the opening 50. Thus, the secondary battery 1 of this embodiment is configured so that the lid member 22 fits into the opening 50 of the case 20 in a state where it is inserted.

[0042] As shown in Fig. 4, in the secondary battery 1 of this embodiment, the lid member 22 fitted into the opening 50 of the case 20 is welded to the opening 50. Specifically, in the secondary battery 1 of this embodiment, aluminum is used as the material of the case body 21 and the lid member 22. Furthermore, welding of the lid member 22 to the opening 50 is performed by irradiating the fitting portion 51 with a laser beam L, that is, so-called laser welding. Note that, for example, a galvano scanner 53 can be used as the laser irradiation portion 52. Thus, the secondary battery 1 of this embodiment is configured to seal the opening 50 of the case 20 to which the lid member 22 is fitted.

[0043] In detail, the lid member 22 of this embodiment has an insulating portion 55 of the electrode terminal 38 that faces the outside of the case 20 in a manner that protrudes from the upper surface 22sa of the lid member 22, which is the outer surface S, when fitted into the opening 50 of the case 20. That is, the secondary battery 1 of this embodiment has a positive electrode terminal 38P and a negative electrode terminal 38N that are provided in a manner that protrudes from the upper surface 22sa of the lid member 22. In addition, the lid member 22 is provided with a pair of insulating portions 55, 55 that protrude from the upper surface 22sa of the lid member 22 in a manner that surrounds the periphery of each of the electrode terminals 38. In the secondary battery 1 of this embodiment, each of the insulating portions 55 and the electrode terminal 38 has a substantially rectangular planar shape. Furthermore, each insulating portion 55 is formed using a resin that has a function of insulating between each of the electrode terminals 38 and the lid member 22 when interposed between them. As a result, the secondary battery 1 of this embodiment is configured such that the laser welding method is different between the peripheral region α1 of each insulating portion 55 provided on the lid member 22 and the non-peripheral region α0 spaced apart from each insulating portion 55 other than the peripheral region α1.

[0044] (The surrounding area of ​​the insulating part and the cutout part of the peripheral wall) As shown in Fig. 5 and Fig. 6, in the secondary battery 1 of this embodiment, the lid member 22 has a pair of electrode terminals 38, 38 serving as a positive electrode terminal 38P and a negative electrode terminal 38N at two positions spaced apart in the longitudinal direction (left-right direction in Fig. 5 and Fig. 6) of the rectangular planar shape. Furthermore, the distance between each of these electrode terminals 38 and the fitting portion 51 of the lid member 22 with respect to the opening 50 of the case 20 is smaller in the short-side direction (up-down direction in Fig. 5) than in the long-side direction based on the elongated shape of the lid member 22. Thus, in the secondary battery 1 of this embodiment, the fitting portion 51 between the opening 50 of the case 20 and the lid member 22 has a peripheral region α1 of each of these insulating portions 55 at a position where the insulating portions 55 of each of the electrode terminals 38 are aligned with the short-side direction of the lid member 22.

[0045] Specifically, the secondary battery 1 of this embodiment has a peripheral area α1 of the insulating portion 55 set at the opening 50 and the fitting portion 51 of the lid member 22 at two positions that sandwich one electrode terminal 38 in the short side direction of the lid member 22. The secondary battery 1 also has a peripheral area α1 of the insulating portion 55 set at the opening 50 and the fitting portion 51 of the lid member 22 for the other electrode terminal 38 at two positions that sandwich the other electrode terminal 38 in the short side direction of the lid member 22.

[0046] As shown in Figs. 5 to 7, in the secondary battery 1 of this embodiment, the peripheral wall 60 of the case 20 forming the opening 50 is provided with cutouts 61 at positions that will be the peripheral regions α1 of the insulating parts 55 when the lid member 22 is fitted. Specifically, each of these cutouts 61 is formed by partially cutting out the opening end 21x of the case body 21 that will be the opening 50 of the case 20. Furthermore, each of these cutouts 61 is provided in the peripheral walls 60a, 60a that form the long side portion of the opening 50 at positions that are aligned with the insulating parts 55 of the electrode terminals 38 and the lid member 22 in the short direction. In the secondary battery 1 of this embodiment, the cutouts 61 are utilized to perform laser welding of the lid member 22 to the opening 50 of the case 20 in the peripheral region α1 of each insulating part 55.

[0047] (Method of welding the area around the insulating part using a notch) As shown in Fig. 4, also in the secondary battery 1 of this embodiment, for the non-peripheral region α0 separated from each insulating portion 55 other than the peripheral region α1, laser welding is performed using a laser irradiation unit 52 arranged above the case 20, as in the conventional technology. That is, for the non-peripheral region α0, laser light L is irradiated to the opening 50 of the case 20 and the fitting portion 51 of the lid member 22 from the insertion direction of the lid member 22 into the opening 50 of the case 20 (from the top to the bottom in Fig. 4). Then, in the secondary battery 1 of this embodiment, the inner periphery of the opening 50 and the outer periphery of the lid member 22, which face each other at the fitting portion 51, are melted, and the opening 50 of the case 20 and the lid member 22 are joined together.

[0048] 7 to 9, in the peripheral region α1 of each insulating portion 55, the outer peripheral surface 22sb of the lid member 22 inserted and fitted into the opening 50 of the case 20 formed by the peripheral wall 60 is exposed in the cutout portion 61 of the peripheral wall 60 provided in each peripheral region α1. Furthermore, in the secondary battery 1 of this embodiment, the laser light L is irradiated to the boundary portion β between the outer peripheral surface 22sb of the lid member 22 exposed in the cutout portion 61 and the end face 61s of the cutout portion 61 at an angle θ inclined with respect to the insertion direction of the lid member 22 into the opening 50. In detail, the laser irradiation unit 52 is arranged outside the opening region γ above the case 20 in the opening direction of the opening 50, and the laser light L is irradiated to the boundary portion β between the outer peripheral surface 22sb of the lid member 22 and the end face 61s of the cutout portion 61. As a result, the secondary battery 1 of this embodiment is configured so that the outer peripheral surface 22sb of the lid member 22 and the end face 61s of the cutout portion 61 melt at the boundary portion β, thereby joining the opening 50 of the case 20 and the lid member 22.

[0049] Specifically, as shown in Fig. 10, a molten portion 65 is formed at a boundary portion β between the outer peripheral surface 22sb of the lid member 22 exposed in the cutout portion 61 and the end surface 61s of the cutout portion 61 by irradiation with laser light L in a manner to fill the cutout portion 61. Furthermore, in the secondary battery 1 of this embodiment, during laser welding in the peripheral region α1 of each insulating portion 55, a corner portion 66 between the outer peripheral surface 22sb of the lid member 22 exposed in the cutout portion 61 and the outer surface S of the lid member 22 from which the insulating portion 55 protrudes is not melted. In other words, a non-molten portion 67 is formed at a corner portion 66 between the outer peripheral surface 22sb of the lid member 22 and the upper surface 22sa of the lid member 22 which is the outer surface S. As a result, the secondary battery 1 of this embodiment is configured such that, when the lid member 22 is welded to the opening 50 of the case 20, the insulating portions 55 of each electrode terminal 38 provided on the lid member 22 are less susceptible to the effects of heat caused by the irradiation of the laser light L to the welded portion.

[0050] 11, a case is assumed in which laser light L is irradiated to a fitting portion 51 with the opening 50 of the case 20 over the entire circumference of the cover member 22, like the secondary battery 71 of the reference example shown in FIG. 11, from the insertion direction of the cover member 22 to the fitting portion 51 with the opening 50. Note that this laser welding is performed in a state in which the case 20 is fixed by a clamp block 73 that also serves as a heat dissipation block.

[0051] In this reference example, the laser irradiation unit 52 is disposed in the opening region γ above the case 20 in the opening direction of the opening 50, that is, above the lid member 22 (not shown). Such an irradiation method of the laser light L is sometimes called "vertical shooting". In this case, when welding the position corresponding to the peripheral region α1 of the insulating part 55, the laser light L irradiated to the opening 50 and the fitting part 51 of the lid member 22 may be reflected and hit the insulating part 55 of the electrode terminal 38 protruding outside the case 20. Furthermore, the plume 75 generated by the heat during the welding, that is, the smoke or spatter of the evaporated metal, may head toward the insulating part 55 and come into contact with the insulating part 55. This causes a problem that the surface of the insulating part 55 formed using the resin is easily affected by heat, such as melting or being so-called "scorched".

[0052] 9 and 12, in the secondary battery 1 of this embodiment, as described above, for the peripheral region α1 of the insulating portion 55, the laser light L is irradiated into the notch portion 61 provided in the peripheral wall 60 of the case 20 that forms the opening 50. Specifically, at this time, the laser irradiation unit 52 is disposed outside the opening region γ of the opening 50 above the case 20 in the opening direction of the opening 50. Thus, the laser light L is irradiated onto the notch portion 61 at an angle θ inclined with respect to the insertion direction of the lid member 22 into the opening 50.

[0053] Such a method of irradiating the laser light L is sometimes called "diagonal irradiation" in contrast to the above-mentioned "vertical irradiation". Furthermore, in the secondary battery 1 of this embodiment, the laser light L is irradiated to the boundary portion β between the outer peripheral surface 22sb of the lid member 22 exposed in the cutout portion 61 and the end surface 61s of the cutout portion 61, that is, the "corner" portion in the cutout portion 61. For this reason, such a method of irradiating the laser light L can also be called "corner irradiation".

[0054] That is, as in the secondary battery 1 of this embodiment, when the peripheral region α1 of the insulating portion 55 is welded, by adopting the above-mentioned "cornering", the irradiated laser light L is less likely to be reflected toward the insulating portion 55 of the electrode terminal 38 protruding outside the case 20. Furthermore, the plume 75 rising from the welded portion by irradiation of the laser light L is also less likely to be directed toward the outer surface S of the lid member 22 on which the insulating portion 55 of the electrode terminal 38 is provided. In particular, in the secondary battery 1 of this embodiment, by not melting the corner portion 66 between the outer peripheral surface 22sb of the lid member 22 located at the upper end of the cutout portion 61 and the upper surface 22sa of the lid member 22 which is the outer surface S, the corner portion 66 having the configuration of the non-melted portion 67 becomes a shielding wall. In addition, when this "cornering" is performed, the laser irradiation portion 52 is not located within the opening region γ of the opening 50 above the case 20 in the opening direction of the opening 50, that is, above the lid member 22. This allows the inert gas G to be efficiently sprayed from the insulating portion 55 side to the peripheral region α1 of the insulating portion 55, which is to be the welding site. Note that, for example, nitrogen gas or the like can be used as the inert gas G. This makes it possible to more effectively protect the insulating portion 55 of the electrode terminal 38 provided on the lid member 22 while welding the peripheral region α1.

[0055] (Welding process for cover parts) Next, the process of welding the cover member 22 to the opening 50 of the case 20 in the secondary battery 1 of this embodiment will be described in detail.

[0056] As shown in Fig. 13, in the secondary battery 1 of this embodiment, when the lid member 22 is welded to the opening 50 of the case 20, first, as a first welding step, welding of the non-peripheral region α0 separated from the insulating portion 55 of each electrode terminal 38 is performed. Specifically, in this first welding step, a laser irradiation unit 52 is used that is disposed within the opening region γ of the opening 50 (see Fig. 11) above the case 20 in the opening direction of the opening 50, that is, above the lid member 22. Then, this first welding step is performed by "vertical firing" in which laser light L is irradiated to the opening 50 of the case 20 and the fitting portion 51 of the lid member 22 from the insertion direction of the lid member 22 into the opening 50.

[0057] More specifically, in this first welding step, "vertical" laser welding is performed in such a manner that the irradiation position of the laser light L on the fitting portion 51 is moved along the circumferential direction of the lid member 22 fitted into the opening 50 of the case 20, excluding the peripheral region α1 of the insulating portion 55. Thus, in the secondary battery 1 of this embodiment, welding of the lid member 22 in the non-peripheral region α0 is completed in this first welding step.

[0058] In the secondary battery 1 of this embodiment, the temporary fixing positions of the lid member 22 relative to the opening 50 of the case 20 are set at a plurality of positions spaced apart in the circumferential direction of the lid member 22 in the non-peripheral region α0. Furthermore, in the first welding step, before the "real welding" of the non-peripheral region α0 by the "vertical driving" as described above, the "temporary welding" of each of these temporary fixing positions is performed by the same "vertical driving". That is, by performing such "temporary welding" in advance, when the "real welding" is performed to move the irradiation position of the laser light L to the opening 50 of the case 20 and the fitting portion 51 of the lid member 22, the deformation of the case 20 due to the generated heat is unlikely to occur. In other words, the planar shape of the rectangular lid member 22 and the opening shape of the opening 50 are unlikely to be distorted. And, in the secondary battery 1 of this embodiment, the lid member 22 is configured to be accurately welded to the opening 50 of the case 20.

[0059] Furthermore, as shown in FIG. 14, in the secondary battery 1 of this embodiment, following the first welding process, a second welding process is performed in which “corner” laser welding is performed on each cutout portion 61 provided in each peripheral region α1 of the insulating portion 55.

[0060] Specifically, this second welding step is performed using a pair of laser irradiation units 52a, 52b arranged at a first lateral position X1 and a second lateral position X2 above the case 20, sandwiching the lid member 22 fitted in the opening 50 opening upward of the case 20 in the short-side direction. That is, each of these laser irradiation units 52a, 52b is arranged outside the opening region γ of the opening 50 above the case 20, which is the opening direction of the opening 50. As a result, the laser light L is irradiated to each of the cutout portions 61 provided in each peripheral region α1 of the insulating portion 55 at an angle θ inclined with respect to the insertion direction of the lid member 22 into the opening 50.

[0061] Thus, in the secondary battery 1 of this embodiment, in the first and second welding steps, "vertical welding" of the non-peripheral region α0 spaced from each insulating portion 55 of the electrode terminal 38 and "corner welding" of the peripheral region α1 of each insulating portion 55 are sequentially performed. This allows the secondary battery 1 of this embodiment to efficiently perform laser welding of the lid member 22 to the opening 50 of the case 20, and is configured so that the insulating portions 55 of the electrode terminals 38 provided on the lid member 22 are less susceptible to the effects of heat.

[0062] (Operation of the first embodiment) For example, as in the case of a secondary battery 81 of a reference example shown in FIG. 15, a case is assumed in which "corner" laser welding is performed around the entire circumference of the lid member 22 fitted into the opening 50 of the case 20, similar to the peripheral region α1 of each insulating portion 55 in the secondary battery 1 of the present embodiment. In addition, in the case of such "corner" laser welding around the entire circumference of the lid member 22, the lid member 22 is fitted into the opening 50 in a state in which the lid member 22 protrudes slightly from the opening end 21x of the case body 21 constituting the opening 50 of the case 20. In other words, the corner portion 66 between the upper surface 22sa and the outer peripheral surface 22sb of the lid member 22 is exposed to the outside of the case 20 around the entire circumference of the lid member 22. Even when such a welding method is adopted, the insulating portion 55 of each electrode terminal 38 provided on the lid member 22 is less susceptible to the influence of the heat.

[0063] However, in the case of using a pair of laser irradiation units 52a, 52b arranged outside the opening region γ of the opening 50 above the case 20, similar to the secondary battery 1 of this embodiment, it is necessary to change the arrangement of these laser irradiation units 52a, 52b or the case 20. That is, the "cornering" of the long side portion of the lid member 22 is performed in a state in which the laser irradiation units 52a, 52b are arranged above the case 20 at two positions that sandwich the lid member 22 fitted into the opening 50 of the case 20 in the short direction, similar to the secondary battery 1 of this embodiment (see FIG. 14). In addition, the "cornering" of the short side portion of the lid member 22 is performed in a state in which the laser irradiation units 52a, 52b are arranged at two positions that sandwich the lid member 22 fitted into the opening 50 of the case 20 in the long direction. This creates a need to change the arrangement of the laser irradiation units 52a, 52b or the case 20 so that the planar shape of the long rectangular lid member 22 is rotated by approximately 90 degrees relative to one another.

[0064] Furthermore, in accordance with the above-mentioned relative rotation, it is necessary to change the distance between the laser irradiation units 52a, 52b arranged at two positions sandwiching the lid member 22 above the case 20. For this reason, when a configuration in which "corner-cut" laser welding is performed around the entire circumference of the lid member 22 is adopted, as in the case of the secondary battery 81 of the reference example shown in Fig. 15, the welding process becomes complicated. In addition, there is a problem that it is difficult to appropriately perform "corner-cut" laser welding on the four corners of the lid member 22, i.e., the portions where the long side portions and short side portions intersect.

[0065] In contrast, in the secondary battery 1 of this embodiment, the "corner-strike" laser welding is performed only on the peripheral region α1 of each insulating portion 55. Then, the non-peripheral region α0 separated from the insulating portion 55 of each electrode terminal 38 is laser-welded by "vertical-strike" laser welding to weld the lid member 22. As a result, it is possible to efficiently weld the lid member 22 to the opening 50 of the case 20 with a simple configuration while suppressing the influence of heat due to the irradiation of the laser light L and appropriately protecting the insulating portion 55 of each electrode terminal 38 provided on the lid member 22.

[0066] (Effects of the first embodiment) Next, the effects of the first embodiment will be described. (1-1) With the secondary battery 1 inserted into an opening 50 of a case 20 that houses an electrode body 10, the opening 50 is sealed by welding a lid member 22 that fits into the opening 50. The lid member 22 is provided with an insulating portion 55 of the electrode terminal 38 that faces the outside of the case 20. A notch 61 is provided in a peripheral wall 60 of the case 20 that forms the opening 50 at a position that will become a peripheral region α1 of the insulating portion 55 when the lid member 22 is fitted. Furthermore, a laser beam L is irradiated onto the opening 50 and the fitting portion 51 of the lid member 22 from the insertion direction of the lid member 22 into the opening 50, thereby welding a non-peripheral region α0 other than the peripheral region α1. Then, for the peripheral region α1, welding is performed by irradiating laser light L at an angle θ inclined with respect to the insertion direction of the cover member 22 to the boundary portion β between the outer peripheral surface 22sb of the cover member 22 exposed in the cutout portion 61 and the end face 61s of the cutout portion 61.

[0067] According to the above configuration, when welding the peripheral region α1 of the insulating portion 55, the irradiated laser light L is less likely to be reflected toward the insulating portion 55 of the electrode terminal 38 protruding outside the case 20. In addition, the plume 75 rising from the welded portion is less likely to be directed toward the outer surface S of the lid member 22 on which the insulating portion 55 is provided. This makes it possible to more effectively protect the insulating portion 55 of the electrode terminal 38 provided on the lid member 22 while welding the lid member 22.

[0068] (1-2) Lid member 22 has a rectangular planar shape and is inserted into opening 50. Notch 61 is provided at a position aligned with insulating portion 55 of electrode terminal 38 in the short direction of lid member 22 fitted into opening 50.

[0069] According to the above configuration, for a case 20 of a secondary battery 1 having a flat, roughly rectangular box-like outer shape that is often used for cells of battery collectors, etc., the cover member 22 can be more suitably welded to the opening 50 having the same rectangular opening shape as the planar shape of the cover member 22.

[0070] (1-3) When welding the lid member 22, a first welding step is performed in which a non-peripheral region α0 other than the peripheral region α1 is welded using the laser irradiation unit 52 arranged above the lid member 22. Then, following this first welding step, a second welding step is performed in which the peripheral region α1 is welded using a pair of laser irradiation units 52a, 52b arranged at a first lateral position X1 and a second lateral position X2 that sandwich the lid member 22 in the short side direction above the case 20.

[0071] According to the above configuration, the influence of heat due to irradiation with laser light L is suppressed, and the insulating portion 55 of the electrode terminal 38 provided on the cover member 22 is appropriately protected, while the cover member 22 can be efficiently welded to the opening 50 of the case 20 with a simple configuration.

[0072] (1-4) When welding the peripheral region α1, the inert gas G is sprayed onto the peripheral region α1 from the insulating portion 55 side above the case 20. According to the above configuration, it is possible to prevent the plume 75 rising from the welded portion from heading in a direction approaching the insulating portion 55 of the electrode terminal 38 provided on the lid member 22. In particular, when the peripheral region α1 is welded, the laser irradiation unit 52 is not positioned above the lid member 22. Therefore, the inert gas G can be efficiently sprayed from the insulating portion 55 side to the peripheral region α1 of the insulating portion 55, which is the welded portion.

[0073] (1-5) The corner 66 between the outer peripheral surface 22sb of the cover member 22 exposed in the cutout portion 61 and the upper surface 22sa of the cover member 22, which is the outer surface S of the outer peripheral surface 22sb, is not melted. According to the above configuration, the corner portion 66 configured as the non-melted portion 67 serves as a shielding wall. This makes it even more difficult for the laser light L reflected from the welded portion and the plume 75 rising from the welded portion to travel toward the insulating portion 55 of the electrode terminal 38 provided on the cover member 22.

[0074] Second embodiment Hereinafter, a second embodiment of a method for manufacturing a secondary battery and a secondary battery will be described with reference to FIGS.

[0075] (Peripheral area of ​​insulating part and extension of peripheral wall) As shown in Fig. 16 and Fig. 17, in the secondary battery 1 of this embodiment, the lid member 22 has a pair of electrode terminals 38, 38 serving as a positive electrode terminal 38P and a negative electrode terminal 38N at two positions spaced apart in the longitudinal direction (left-right direction in Fig. 16 and Fig. 17) of the rectangular planar shape. Furthermore, the distance between each of these electrode terminals 38 and the fitting portion 51 of the lid member 22 with respect to the opening 50 of the case 20 is smaller in the short-side direction (up-down direction in Fig. 16) than in the long-side direction based on the elongated shape of the lid member 22. Thus, in the secondary battery 1 of this embodiment, the fitting portion 51 between the opening 50 of the case 20 and the lid member 22 has a peripheral region α1 of each of these insulating portions 55 at a position where the insulating portions 55 of each of the electrode terminals 38 are aligned with the short-side direction of the lid member 22.

[0076] Specifically, the secondary battery 1 of this embodiment has a peripheral area α1 of the insulating portion 55 set at the opening 50 and the fitting portion 51 of the lid member 22 at two positions that sandwich one electrode terminal 38 in the short side direction of the lid member 22. The secondary battery 1 also has a peripheral area α1 of the insulating portion 55 set at the opening 50 and the fitting portion 51 of the lid member 22 for the other electrode terminal 38 at two positions that sandwich the other electrode terminal 38 in the short side direction of the lid member 22.

[0077] As shown in Figs. 16 to 18, in the secondary battery 1 of this embodiment, the peripheral wall 90 of the case 20 forming the opening 50 is provided with extensions 91 at positions that become the peripheral regions α1 of the insulating parts 55 when the lid member 22 is fitted. Specifically, each of these extensions 91 is formed by partially extending the opening end 21x of the case body 21 that becomes the opening 50 of the case 20 in the insertion direction of the lid member 22. Furthermore, each of these extensions 91 is provided in the peripheral walls 90a, 90a that form the long side portion of the opening 50 at positions that are aligned with the insulating parts 55 of the electrode terminals 38 in the short direction of the lid member 22. In the secondary battery 1 of this embodiment, the extensions 91 are utilized to perform laser welding of the lid member 22 to the opening 50 of the case 20 in the peripheral region α1 of each insulating part 55.

[0078] (Method of welding the area around the insulating part using the extension part) As shown in Fig. 4, also in the secondary battery 1 of this embodiment, for the non-peripheral region α0 separated from each insulating portion 55 other than the peripheral region α1, laser welding is performed using a laser irradiation unit 52 arranged above the case 20, as in the conventional technology. That is, for the non-peripheral region α0, laser light L is irradiated to the opening 50 of the case 20 and the fitting portion 51 of the lid member 22 from the insertion direction of the lid member 22 into the opening 50 of the case 20 (from the top to the bottom in Fig. 4). Then, in the secondary battery 1 of this embodiment, the inner periphery of the opening 50 and the outer periphery of the lid member 22, which face each other at the fitting portion 51, are melted, and the opening 50 of the case 20 and the lid member 22 are joined together.

[0079] As shown in Figs. 18 to 20, in the peripheral region α1 of each insulating portion 55, the lower portion of each insulating portion 55 is hidden in a side view by the extension portion 91 of the peripheral wall 90 provided in each peripheral region α1. Furthermore, in the secondary battery 1 of this embodiment, the laser light L is irradiated to the outer surface 91a of the portion having the extension portion 91 at an angle θ inclined with respect to the insertion direction of the lid member 22 into the opening 50. In detail, the laser light L is irradiated to the irradiation portion δ located outside the peripheral wall 90a facing the outer peripheral surface 22sb of the lid member 22 in a state where the laser irradiation portion 52 is arranged outside the opening region γ above the case 20 in the opening direction of the opening 50. Then, in the secondary battery 1 of this embodiment, the peripheral wall 90a and the lid member 22 are melted through the irradiation portion δ of the peripheral wall 90a of the case 20, so that the opening 50 of the case 20 and the lid member 22 are joined. Incidentally, for example, this laser welding is performed in a state where the case 20 is fixed by a clamp block 73 which also serves as a heat dissipation device.

[0080] Specifically, as shown in Figs. 20 and 21, the laser light L is irradiated to the irradiated portion δ located outside the peripheral wall 90a facing the outer peripheral surface 22sb of the lid member 22, and the molten portion 95 is formed in such a manner that the molten portion 95 penetrates the peripheral wall 90a and includes the lid member 22. In other words, the molten portion 95 is formed on the outer surface 91a of the portion having the extension portion 91 of the case 20. Furthermore, in the secondary battery 1 of this embodiment, when the peripheral region α1 of each insulating portion 55 is laser-welded, the laser light L penetrates the case 20 and is irradiated toward the insulating portion 55 in the thickness direction of the lid member 22. Thus, in the secondary battery 1 of this embodiment, when the lid member 22 is welded to the opening 50 of the case 20, the insulating portion 55 of each electrode terminal 38 provided on the lid member 22 is not easily affected by the heat caused by the irradiation of the laser light L to the welding portion.

[0081] As shown in Figs. 20 and 21, in the secondary battery 1 of this embodiment, as described above, for the peripheral region α1 of the insulating portion 55, the laser light L is irradiated to the irradiation portion δ of the peripheral wall 90 of the case 20 forming the opening 50. Specifically, at this time, the laser irradiation portion 52 is disposed outside the opening region γ of the opening 50 in the upper part of the case 20 in the opening direction of the opening 50. Then, the laser light L is irradiated to the irradiation portion δ at an angle θ inclined with respect to the insertion direction of the lid member 22 into the opening 50. Since the laser light L is irradiated at the angle θ, it is desirable that the irradiation portion δ is located on the upper side of the outer side of the peripheral wall 90a facing the outer circumferential surface 22sb of the lid member 22. The angle θ is desirably, for example, 60 degrees or less.

[0082] Such a method of irradiating the laser light L is sometimes called "diagonal irradiation" in contrast to "vertical irradiation". Furthermore, in the secondary battery 1 of this embodiment, the laser light L is irradiated to the irradiation portion δ of the outer surface 91a of the portion having the extension portion 91, that is, the "side surface" portion of the peripheral wall 90 of the case 20. For this reason, such a method of irradiating the laser light L can also be called "side surface irradiation".

[0083] That is, as shown in FIG. 22, when welding the peripheral region α1 of the insulating portion 55 as in the secondary battery 1 of this embodiment, by adopting the above-mentioned "side shot", the irradiated laser light L is less likely to be reflected toward the insulating portion 55 of the electrode terminal 38 protruding outside the case 20. Furthermore, the plume 75 rising from the welding portion by irradiation of the laser light L is also less likely to be directed toward the outer surface S of the lid member 22 on which the insulating portion 55 of the electrode terminal 38 is provided. In particular, in the secondary battery 1 of this embodiment, the extension portion 91 protrudes from the outer surface S of the lid member 22, so that the extension portion 91 serves as a shielding wall. In addition, during this "side shot", the laser irradiation portion 52 is not located within the opening region γ of the opening 50 above the case 20 in the opening direction of the opening 50, that is, above the lid member 22. Therefore, it is possible to efficiently blow the inert gas G from above the outside of the case 20 to the peripheral region α1 of the insulating portion 55 that is the welding portion. Incidentally, for example, nitrogen gas or the like can be used as the inert gas G. In the secondary battery 1 of this embodiment, this makes it possible to more effectively protect the insulating portion 55 of the electrode terminal 38 provided on the lid member 22 while welding the peripheral region α1 thereof.

[0084] (Welding process for cover parts) Next, the process of welding the cover member 22 to the opening 50 of the case 20 in the secondary battery 1 of this embodiment will be described in detail.

[0085] As shown in Fig. 13, in the secondary battery 1 of this embodiment, when the lid member 22 is welded to the opening 50 of the case 20, first, as a first welding step, welding of the non-peripheral region α0 separated from the insulating portion 55 of each electrode terminal 38 is performed. Specifically, in this first welding step, a laser irradiation unit 52 is used that is disposed within the opening region γ of the opening 50 (see Fig. 11) above the case 20 in the opening direction of the opening 50, that is, above the lid member 22. Then, this first welding step is performed by "vertical firing" in which laser light L is irradiated to the opening 50 of the case 20 and the fitting portion 51 of the lid member 22 from the insertion direction of the lid member 22 into the opening 50.

[0086] More specifically, in this first welding step, "vertical" laser welding is performed in such a manner that the irradiation position of the laser light L on the fitting portion 51 is moved along the circumferential direction of the lid member 22 fitted into the opening 50 of the case 20, excluding the peripheral region α1 of the insulating portion 55. Thus, in the secondary battery 1 of this embodiment, welding of the lid member 22 in the non-peripheral region α0 is completed in this first welding step.

[0087] In the secondary battery 1 of this embodiment, the temporary fixing positions of the lid member 22 relative to the opening 50 of the case 20 are set at a plurality of positions spaced apart in the circumferential direction of the lid member 22 in the non-peripheral region α0. Furthermore, in the first welding step, before the "real welding" of the non-peripheral region α0 by the "vertical driving" as described above, the "temporary welding" of each of these temporary fixing positions is performed by the same "vertical driving". That is, by performing such "temporary welding" in advance, when the "real welding" is performed to move the irradiation position of the laser light L to the opening 50 of the case 20 and the fitting portion 51 of the lid member 22, the deformation of the case 20 due to the generated heat is unlikely to occur. In other words, the planar shape of the rectangular lid member 22 and the opening shape of the opening 50 are unlikely to be distorted. And, in the secondary battery 1 of this embodiment, the lid member 22 is configured to be accurately welded to the opening 50 of the case 20.

[0088] Furthermore, as shown in FIG. 23, in the secondary battery 1 of this embodiment, following the first welding process, a second welding process is performed in which “side-hit” laser welding is performed on the irradiated portion δ of the outer surface 91a of the portion having each extension portion 91 provided in each peripheral region α1 of the insulating portion 55.

[0089] Specifically, this second welding step is performed using a pair of laser irradiation units 52a, 52b arranged at a first lateral position X1 and a second lateral position X2 above the case 20, sandwiching the lid member 22 fitted in the opening 50 opening upward of the case 20 in the short-side direction. That is, each of these laser irradiation units 52a, 52b is arranged outside the opening region γ of the opening 50 above the case 20, which is the opening direction of the opening 50. As a result, the laser light L is irradiated to the irradiation portion δ of the outer surface 91a of the portion having each extension portion 91 provided in each peripheral region α1 of the insulating portion 55 at an angle θ inclined with respect to the insertion direction of the lid member 22 into the opening 50.

[0090] Thus, in the secondary battery 1 of this embodiment, in the first welding step and the second welding step, "vertical welding" of the non-peripheral region α0 spaced apart from each insulating portion 55 of the electrode terminal 38 and "side welding" of the peripheral region α1 of each insulating portion 55 are sequentially performed. This allows the secondary battery 1 of this embodiment to efficiently perform laser welding of the lid member 22 to the opening 50 of the case 20, and is configured so that the insulating portions 55 of each electrode terminal 38 provided on the lid member 22 are less susceptible to the effects of heat.

[0091] (Operation of the second embodiment) In the secondary battery 1 of this embodiment, the "side-strike" laser welding is performed only on the peripheral region α1 of each insulating portion 55. Then, the non-peripheral region α0 separated from the insulating portion 55 of each electrode terminal 38 is laser-welded by "vertical strike" to weld the lid member 22. As a result, it is possible to efficiently weld the lid member 22 to the opening 50 of the case 20 with a simple configuration while suppressing the influence of heat due to the irradiation of the laser light L and appropriately protecting the insulating portion 55 of each electrode terminal 38 provided on the lid member 22.

[0092] (Effects of the second embodiment) Next, the effects of the second embodiment will be described. (2-1) The secondary battery 1 is inserted into the opening 50 of the case 20 that houses the electrode body 10, and the opening 50 is sealed by welding the lid member 22 that fits into the opening 50. The lid member 22 is provided with an insulating portion 55 of the electrode terminal 38 that faces the outside of the case 20. In addition, an extension portion 91 is provided on the peripheral wall 90 of the case 20 that forms the opening 50 at a position that becomes the peripheral region α1 of the insulating portion 55 when the lid member 22 is fitted. Furthermore, the non-peripheral region α0 other than the peripheral region α1 is welded by irradiating the opening 50 and the fitting portion 51 of the lid member 22 with laser light L from the insertion direction of the lid member 22 into the opening 50. Then, the peripheral region α1 is welded by irradiating the irradiation portion δ of the outer surface 91a of the portion having the extension portion 91 with laser light L at an angle θ inclined with respect to the insertion direction of the lid member 22.

[0093] According to the above method, when welding the peripheral region α1 of the insulating portion 55, the irradiated laser light L is less likely to be reflected toward the insulating portion 55 of the electrode terminal 38 protruding outside the case 20. In addition, the plume 75 rising from the welded portion is less likely to be directed toward the outer surface S of the lid member 22 on which the insulating portion 55 is provided. This makes it possible to more effectively protect the insulating portion 55 of the electrode terminal 38 provided on the lid member 22 while welding the lid member 22.

[0094] (2-2) Lid member 22 has a rectangular planar shape and is inserted into opening 50. Extension portion 91 is provided at a position aligned with insulating portion 55 of electrode terminal 38 in the short-side direction of lid member 22 fitted into opening 50.

[0095] According to the above method, for a case 20 of a secondary battery 1 having a flat, roughly square box-like outer shape that is often used for cells of battery collectors, etc., the cover member 22 can be more suitably welded to the opening 50 having the same rectangular opening shape as the planar shape of the cover member 22.

[0096] (2-3) When welding the lid member 22, a first welding step is performed in which a non-peripheral region α0 other than the peripheral region α1 is welded using the laser irradiation unit 52 arranged above the lid member 22. Then, following this first welding step, a second welding step is performed in which the peripheral region α1 is welded using a pair of laser irradiation units 52a, 52b arranged at a first lateral position X1 and a second lateral position X2 that sandwich the lid member 22 in the short side direction above the case 20.

[0097] According to the above method, the influence of heat due to irradiation with laser light L is suppressed, and the insulating portion 55 of the electrode terminal 38 provided on the cover member 22 is appropriately protected, while the cover member 22 can be efficiently welded to the opening 50 of the case 20 with a simple configuration.

[0098] (2-4) When welding the peripheral region α1, the inert gas G is sprayed onto the peripheral region α1 from above and outside the case 20. According to the above configuration, it is possible to prevent the plume 75 rising from the welding portion from heading in a direction approaching the insulating portion 55 of the electrode terminal 38 provided on the lid member 22. In particular, when the peripheral region α1 is welded, the laser irradiation unit 52 is not positioned above the lid member 22. Therefore, the inert gas G can be efficiently sprayed from above the case 20 onto the peripheral region α1 of the insulating portion 55, which is the welding portion.

[0099] (2-5) The laser light L irradiated to the peripheral region α1 penetrates the case 20 and is irradiated toward the insulating portion 55 in the thickness direction of the lid member 22. According to the above method, it is possible to prevent the laser light L that has penetrated from being deviated from the cover member 22 and entering the inside of the case 20 and irradiating the electrode body 10.

[0100] (Other embodiments) The above-described embodiments may be modified as follows: The above-described embodiments and the following modifications may be combined with each other to the extent that no technical contradiction occurs.

[0101] In the above embodiments, aluminum is used as the material of the case body 21 and the lid member 22 that constitute the case 20. However, this is not limited to this, and other metals may be used. Furthermore, the case body 21 and the lid member 22 may be made of different metals.

[0102] In each of the above-described embodiments, the opening 50 of the case 20 has a rectangular opening shape facing upward. The lid member 22 also has a rectangular planar shape that is substantially the same as the opening shape of the opening 50.

[0103] However, the present invention is not limited thereto, and the opening shape of the opening 50 and the planar shape of the lid member 22 may be arbitrarily changed. Furthermore, the arrangement of the electrode terminals 38 provided on the lid member 22 may also be arbitrary. That is, the peripheral area α1 of the insulating portion 55 may be arbitrarily set. Furthermore, at the set position of the peripheral area α1, the number and shapes of the notches 61 provided on the peripheral wall 60 and the extensions 91 provided on the peripheral wall 90 that form the opening 50 of the case 20 may also be arbitrarily changed in accordance with the arrangement of the electrode terminals 38.

[0104] In addition, in each of the above embodiments, the case 20 has the case body 21 in the shape of a flattened, generally rectangular box, but the shape of the case 20 may be changed as desired. Also, the opening 50 does not necessarily have to open upward.

[0105] In each of the above embodiments, when welding the non-peripheral region α0, the irradiation angle of the laser light L applied to the opening 50 and the fitting portion 51 of the lid member 22 from the insertion direction of the lid member 22 is also arbitrary. Moreover, the position of the laser irradiation unit 52 during this so-called "vertical firing" does not necessarily have to be within the opening region γ of the opening 50 above the case 20.

[0106] In the above first embodiment, when welding the peripheral region α1 of the insulating portion 55, the angle θ at which the laser light L is irradiated to the boundary portion β between the outer peripheral surface 22sb of the cover member 22 exposed in the cutout portion 61 and the end face 61s of the cutout portion 61 may be set arbitrarily.

[0107] In the first embodiment, first, so-called "vertical" laser welding is performed on the non-peripheral region α0 other than the peripheral region α1 of the insulating portion 55. Then, so-called "corner" laser welding is performed on the peripheral region α1 of the insulating portion 55. However, this is not limiting, and a configuration in which "corner" laser welding on the peripheral region α1 of the insulating portion 55 is performed first may be used.

[0108] In the second embodiment, when welding the peripheral region α1 of the insulating portion 55, the angle θ at which the laser light L is irradiated to the irradiation portion δ of the outer surface 91a of the portion having the extension portion 91 may be set arbitrarily.

[0109] In the second embodiment, first, so-called "vertical" laser welding is performed on the non-peripheral region α0 other than the peripheral region α1 of the insulating portion 55. Then, so-called "side" laser welding is performed on the peripheral region α1 of the insulating portion 55. However, this is not limiting, and a configuration in which "side" laser welding on the peripheral region α1 of the insulating portion 55 is performed first may be used.

[0110] In the second embodiment described above, the laser light L irradiated to the peripheral region α1 penetrates the case 20 and is irradiated toward the insulating portion 55 in the thickness direction of the lid member 22. However, this is not limited thereto, and the laser light L irradiated to the peripheral region α1 does not have to penetrate the case 20 and be irradiated toward the insulating portion 55 in the thickness direction of the lid member 22 as long as it is not irradiated to the electrode body 10 inside the case 20.

[0111] In each of the above embodiments, nitrogen gas is exemplified as the inert gas G to be sprayed onto the peripheral region α1 of the insulating portion 55 that is to be the welding site. However, the inert gas G to be used may be changed as desired.

[0112] In each of the above embodiments, the electrode assembly 10 of the secondary battery 1 has a configuration as a wound body, but the positive and negative electrode sheets 35P, 35N stacked with the separator 5 sandwiched therebetween do not necessarily have to be wound. In addition, the secondary battery 1 does not necessarily have to be a lithium ion secondary battery, and may be applied to other non-aqueous electrolyte secondary batteries. The terminal shapes of the positive electrode terminal 38P and the negative electrode terminal 38N are also not limited to the shapes shown in FIG. 1 and may be arbitrarily changed. [Explanation of symbols]

[0113] 1…Secondary battery 10...Electrode body 20…Case 22...Cover member 22sb…outer surface 38...Electrode terminal 50…Opening 51...Fitting part 55…Insulation section 60...Peripheral wall 61...Notch 61s...end face 73…Clamp block 90,90a…peripheral wall 91...Extending part 91a…External surface 95…Melted part G…Inert gas L…Laser light S...Outer surface α1…peripheral area α0: Non-peripheral area β...boundary part γ...Aperture area δ…Irradiation part θ…Angle

Claims

1. A method for manufacturing a secondary battery, comprising the steps of: sealing an opening of a case that houses an electrode assembly by welding a cover member that is fitted into the opening while the cover member is inserted into the opening; and insulating portions of electrode terminals that face outside the case are provided on the cover member, a peripheral wall of the case that defines the opening has a notch that is provided at a position that corresponds to a peripheral region of the insulating portion when the cover member is fitted to the peripheral wall; The welding is performed in a region other than the peripheral region by irradiating the opening and the fitting portion of the lid member with a laser beam from an insertion direction of the lid member into the opening, The welding of the peripheral region is performed by irradiating the laser light at an angle inclined with respect to the insertion direction of the cover member to a boundary portion between an outer peripheral surface of the cover member exposed in the cutout portion and an end face of the cutout portion. A method for manufacturing a secondary battery.

2. The cover member has a rectangular planar shape and is inserted into the opening. The notch portion is provided at a position aligned with the insulating portion in a short-side direction of the cover member fitted in the opening. The method for producing the secondary battery according to claim 1 .

3. a first welding step of performing the welding other than the peripheral region by using a laser irradiation unit disposed above the lid member; a second welding step of welding the peripheral region using a pair of the laser irradiation units arranged at a first lateral position and a second lateral position that sandwich the lid member in a short side direction above the case. The method for producing the secondary battery according to claim 2 .

4. When performing the welding of the peripheral region, an inert gas is blown onto the peripheral region from the insulating portion side above the case. A method for producing the secondary battery according to any one of claims 1 to 3.

5. The corner between the outer peripheral surface of the cover member exposed in the notch and the outer surface of the cover member from which the insulating portion protrudes is not melted. A method for producing the secondary battery according to any one of claims 1 to 3.

6. A method for manufacturing a secondary battery, comprising the steps of: sealing an opening of a case that houses an electrode assembly by welding a cover member that is fitted into the opening while the cover member is inserted into the opening; and insulating portions of electrode terminals that face outside the case are provided on the cover member, a peripheral wall of the case that defines the opening has an extension portion that extends in an insertion direction of the cover member at a position that becomes a peripheral region of the insulating portion when the cover member is fitted in the fitting state; The welding is performed in a region other than the peripheral region by irradiating the opening and the fitting portion of the lid member with a laser beam from an insertion direction of the lid member into the opening, The laser beam is irradiated to the outer surface of the portion of the case having the extension at an angle inclined with respect to the insertion direction of the lid member to perform penetration welding between the case and the lid member, thereby performing the welding of the peripheral region. A method for manufacturing a secondary battery.

7. The cover member has a rectangular planar shape and is inserted into the opening. The extension portion is provided at a position aligned with the insulating portion in a short-side direction of the cover member fitted in the opening. The method for producing a secondary battery according to claim 6 .

8. a first welding step of performing the welding other than the peripheral region by using a laser irradiation unit disposed above the lid member; a second welding step of welding the peripheral region using a pair of the laser irradiation units arranged at a first lateral position and a second lateral position that sandwich the lid member in a short side direction above the case. The method for producing the secondary battery according to claim 7 .

9. When performing the welding of the peripheral region, an inert gas is sprayed onto the peripheral region from above the outside of the case. A method for producing the secondary battery according to any one of claims 6 to 8.

10. The laser light irradiated to the peripheral region penetrates the case and is irradiated toward the insulating portion in the thickness direction of the lid member. A method for producing the secondary battery according to any one of claims 6 to 8.

11. a cover member welded to an opening of a case that houses the electrode assembly and is inserted into the opening, the cover member has an insulating portion for an electrode terminal that faces the outside of the case, A peripheral wall of the case that defines the opening has a notch at a position that corresponds to a peripheral region of the insulating portion, a fusion zone at a boundary between an outer peripheral surface of the cover member exposed in the cutout portion and an end surface of the cutout portion; a non-melted portion at a corner between an outer peripheral surface of the lid member exposed in the cutout portion and an outer surface of the lid member from which the insulating portion protrudes; Secondary battery.

12. a cover member welded to an opening of a case that houses the electrode assembly and is inserted into the opening, the cover member has an insulating portion for an electrode terminal that faces the outside of the case, A peripheral wall of the case that defines the opening has an extension portion that extends in an insertion direction of the cover member at a position that is to become a peripheral region of the insulating portion, The case has a fusion zone on the outer surface of the portion having the extension. Secondary battery.

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