Method of manufacturing secondary battery and secondary battery

Abstract

To attain suppression of occurrence of laser penetration when joining a case body and a sealing plate.SOLUTION: A method of manufacturing a secondary battery includes the steps of: positioning a case body 30 and a sealing plate 40 so as to provide a level difference between an edge portion 37 and an outer end surface 46 of the sealing plate 40 in a first direction; and when the level difference is defined as H1, a maximum clearance between an opening 35 and the outer end surface 46 in a second direction orthogonal to the first direction is defined as L, and an inclination angle θ of an optical axis A of laser light 4 with respect to the first direction is defined as θ, joining portions of the case body 30 and the sealing plate 40 by irradiating the edge portion 37 and the outer end surface 46 with the laser light 4 with the optical axis A being inclined at an angle equal to or more than a numerical value of θ that satisfies a relation of tan θ=L / H1.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] Japanese Patent Laid-Open Publication No. 2018-202478 (Patent Document 1) is a prior art document that discloses the configuration of a laser sealing device. The laser sealing device described in Patent Document 1 covers the opening of a container and seals the opening with a laser beam. The laser beam is split into a first laser beam and a second laser beam. The first laser beam is irradiated near the joining surface of the opening of the container. The second laser beam is irradiated near the joining surface of the lid. Since the laser beam is less likely to hit the joining surface, spatter is suppressed from occurring on the joining surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-202478 Summary of the Invention [Problem to be solved by the invention]

[0004] In the laser sealing device described in Patent Document 1, if the gap between the case body and the sealing plate becomes larger than the irradiation position of the divided laser beams, the laser beam may enter the inside of the battery from between the case body and the sealing plate, which is known as laser leakage. In this case, the electrode body in the battery may be damaged by the laser beam being irradiated on the electrode body in the battery.

[0005] The present technology has been made to solve the above-mentioned problems, and aims to provide a method for manufacturing a secondary battery that can suppress the occurrence of laser voids when joining the case body and the sealing plate, and a secondary battery. [Means for solving the problem]

[0006] The present technology provides the following method for manufacturing a secondary battery.

[0007] [1] a step of preparing an electrode body, a case body having an edge portion defining an opening at one end in a first direction, and a sealing plate capable of sealing the opening; a step of accommodating the electrode body in the case body through the opening; positioning the case body and the sealing plate so that a step is provided between the edge portion and an outer end face of the sealing plate that is located on the opposite side to an inner end face that faces the electrode body in the first direction; When the step is H1, the maximum gap between the opening and the outer end surface in a second direction perpendicular to the first direction is L, and the tilt angle of the optical axis of the laser light with respect to the first direction is θ, irradiating the edge and the outer end surface with the laser light, the optical axis of which is tilted at an angle equal to or greater than the value of θ that satisfies the relationship tanθ=L / H1, to join a portion of the case body and the sealing plate.

[0008] [2] In the step of joining a portion of the case body and the sealing plate, The step H1 is equal to or greater than 0.3 mm and equal to or less than 1.4 mm, The maximum gap L is 0.05 mm or more and 0.2 mm or less, The method for manufacturing a secondary battery according to [1], wherein the inclination angle θ is equal to or greater than 2° and equal to or less than 10°, and satisfies the relationship tan θ=L / H1.

[0009] [3] In the step of positioning the case body and the sealing plate, The method for manufacturing a secondary battery according to [1] or [2], wherein the outer end surface is positioned farther from the electrode body than the edge portion in the first direction.

[0010] [4] The edge portion includes a first portion located on an outer circumferential side and a second portion located on an inner circumferential side, the first portion is provided so as to protrude further outward from the case body than the second portion in the first direction, The method for manufacturing a secondary battery according to any one of [1] to [3], wherein in the step of positioning the case body and the sealing plate, the second part and the sealing plate abut in the first direction.

[0011] The present technology provides the following secondary battery.

[0012] [5] An electrode body; a case body that houses the electrode body and has an edge that defines an opening at one end in a first direction; a sealing plate including an inner end surface facing the electrode body and an outer end surface located on the opposite side to the inner end surface, and sealing the opening, The opening has a shape that allows the electrode body to be inserted therethrough, a joint portion is formed to join the edge portion and the outer end surface; a step is provided between an end of the joint portion and the outer end surface in the first direction, The secondary battery, wherein the step is 0.23 mm or more and 1 / 7 or less of the thickness of the sealing plate in the first direction.

[0013] [6] The secondary battery according to [5], wherein the outer end surface is farther from the electrode body in the first direction than the edge portion. [Effects of the Invention]

[0014] According to the present technology, it is possible to suppress the occurrence of laser voids when joining the case body and the sealing plate. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view showing a configuration of a secondary battery according to a first embodiment of the present technology. [Figure 2] 2 is a cross-sectional view of the structure of the periphery of the joint between the case body and the sealing plate of FIG. 1, as viewed in the direction of the arrows along line II-II. [Figure 3] 3 is a flowchart showing a method for manufacturing a secondary battery according to the first embodiment of the present technology. [Figure 4] FIG. 2 is a perspective view showing a state in which an electrode body is inserted into a case main body. [Figure 5] 1 is a cross-sectional view showing a state in which a case body and a sealing plate are positioned according to the first embodiment of the present technology. [Figure 6] FIG. 10 is a top view showing the position where the case body and the sealing plate are temporarily joined. [Figure 7] 1 is a cross-sectional view showing the positional relationship between a case body, a sealing plate, and the tilt angle of a laser when the case body and the sealing plate are temporarily joined together in accordance with the first embodiment of the present technology. [Figure 8] FIG. 10 is a cross-sectional view showing the inclination angle of the laser beam when the case body and the sealing plate are temporarily joined together. [Figure 9] FIG. 10 is a cross-sectional view showing the positional relationship between the case body, the sealing plate, and the tilt angle of the laser when the case body and the sealing plate are temporarily joined together in a comparative example. [Figure 10] 10 is a graph showing the results of a test to confirm whether or not laser leakage occurs when joining the case body and the sealing plate, based on the correlation between the first step, the maximum gap, and the tilt angle of the laser. [Figure 11] 10 is a graph showing the region where laser leakage does not occur when joining the case body and the sealing plate, based on the correlation between the laser irradiation angle and the first step for each gap between the case body and the sealing plate. [Figure 12] 2 is a cross-sectional view showing a configuration of a joint between a case body and a sealing plate according to the first embodiment of the present technology. [Figure 13] 10 is a graph showing the correlation between the first step and the second step. [Figure 14] 10 is a cross-sectional view showing the positional relationship between a case body, a sealing plate, and the tilt angle of a laser when the case body and the sealing plate are temporarily joined together in accordance with a second embodiment of the present technology. FIG. [Figure 15]FIG. 11 is a cross-sectional view showing a state in which a case body and a sealing plate are positioned according to a third embodiment of the present technology. [Figure 16] 11 is a flowchart showing a method for manufacturing a secondary battery according to a third embodiment of the present technology. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

[0017] In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiments.

[0018] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain feature is included, other features may or may not be included.

[0019] Furthermore, when geometric terms and terms expressing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in a single state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0020] In this specification, the term "secondary battery" is not limited to lithium ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium ion batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode.

[0021] Furthermore, "secondary batteries" can be installed in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs), etc. However, the use of "secondary batteries" is not limited to in-vehicle use.

[0022] In the drawings, the direction in which the positive and negative electrode terminals of the secondary battery are aligned is the X direction, the direction in which the first and second side surfaces of the case are aligned is the Y direction, and the Z direction, which is the first direction, is the direction perpendicular to the plane in which the main surface of the outer end surface of the sealing plate extends. The direction parallel to the plane in which the main surface of the outer end surface of the sealing plate extends is the second direction. Furthermore, for the sake of convenience, the scale of each component of the secondary battery has been changed in the drawings, and some of the components have been omitted for illustrative purposes.

[0023] (Embodiment 1) First, the overall structure of the secondary battery will be described. Fig. 1 is a perspective view showing the configuration of a secondary battery according to a first embodiment of the present technology.

[0024] 1, the secondary battery 1 has a rectangular shape. The secondary battery 1 is, for example, a lithium ion battery. The secondary battery 1 according to the first embodiment of the present technology includes an electrode assembly 10 and a case 20.

[0025] The electrode body 10 in this embodiment is, for example, a wound electrode body. Furthermore, the electrode body 10 is not limited to a wound electrode body, and may be a laminated (stacked) electrode body.

[0026] The electrode assembly 10 includes a positive electrode, a negative electrode, and a separator (not shown). The positive electrode, negative electrode, and separator are all strip-shaped sheets. The separator is sandwiched between the positive electrode and negative electrode. The electrode assembly 10 is formed by winding a laminate of the positive electrode, negative electrode, and separator. A separator is disposed on the outermost periphery of the wound electrode assembly 10.

[0027] The case 20 has a rectangular parallelepiped shape and forms the external appearance of the secondary battery 1. The case 20 accommodates the electrode assembly 10 and an electrolyte solution (not shown). The case 20 is made of, for example, an aluminum alloy.

[0028] The case 20 includes a case body 30 and a sealing plate 40. The case body 30 houses the electrode assembly 10.

[0029] The case body 30 has a bottom surface portion 31, a first side surface portion 32, a second side surface portion 33, and a third side surface portion .

[0030] The bottom surface portion 31 is made of a flat surface that is perpendicular to the Z direction. The bottom surface portion 31 faces the sealing plate 40 in the Z direction.

[0031] Each side of the first side surface portion 32 and the second side surface portion 33 is formed of a plane perpendicular to the Y direction. The first side surface portion 32 and the second side surface portion 33 face each other in the Y direction. Each side of the first side surface portion 32 and the second side surface portion 33 has the largest area among the multiple side surfaces of the case body 30. Each side of the first side surface portion 32 and the second side surface portion 33 has a rectangular shape when viewed in the Y direction. When viewed in the Y direction, each side of the first side surface portion 32 and the second side surface portion 33 has a rectangular shape with the X direction as the longitudinal direction and the Z direction as the lateral direction. Each side of the first side surface portion 32 and the second side surface portion 33 stands upright from the bottom surface portion 31.

[0032] The third side surface portion 34 is made of a flat surface perpendicular to the X direction. A pair of third side surface portions 34 is provided on the secondary battery 1. The pair of third side surface portions 34 are arranged side by side in the X direction. The pair of third side surface portions 34 are erected from the bottom surface portion 31. Each of the pair of third side surface portions 34 connects the ends of the first side surface portion 32 and the second side surface portion 33 to each other.

[0033] An opening 35, which will be described later, is formed in the case body 30. The opening 35 is formed by the ends of the first side surface portion 32, the second side surface portion 33, and a pair of third side surface portions 34 in the Z direction. The opening 35 has a shape that allows the electrode body 10 to be inserted therethrough.

[0034] The sealing plate 40 is a flat plate extending on the XY plane. The sealing plate 40 seals the opening 35.

[0035] An electrode terminal 41 is provided on the sealing plate 40. The electrode terminals include a positive electrode terminal 42 and a negative electrode terminal 43. The positive electrode terminal 42 and the negative electrode terminal 43 are spaced apart from each other in the X direction. The positive electrode terminal 42 and the negative electrode terminal 43 are joined to a bus bar (not shown) by laser welding or the like.

[0036] A plurality of secondary batteries 1 are arranged in the Y direction. The plurality of secondary batteries 1 are stacked such that the first side surface portions 32 and the second side surface portions 33 of the secondary batteries 1 adjacent to each other in the Y direction face each other. As a result, the positive electrode terminals 42 and the negative electrode terminals 43 are alternately arranged in the Y direction in which the plurality of secondary batteries 1 are stacked.

[0037] 2 is a cross-sectional view of the structure around the joint between the case body and the sealing plate in FIG. 1, as viewed in the direction of the arrows along line II-II.

[0038] The case body 30 has a post-joining edge 36. The post-joining edge 36 defines an opening 35 at one end of the case body 30 in the first direction (Z direction). In this embodiment, the post-joining edge 36 is the interface between the joint 50 (the portion where the case body and the sealing plate are fused together) and the portion formed only by the case body 30.

[0039] The sealing plate 40 includes an inner end surface 45 and an outer end surface 46. The inner end surface 45 is the surface located on the inner space side of the case body 30. The inner end surface 45 extends on the XY plane. The inner end surface 45 faces the electrode body 10.

[0040] The outer end surface 46 is a surface located on the outside of the secondary battery 1. The outer end surface 46 extends on the XY plane. The outer end surface 46 is located on the opposite side of the inner end surface 45 in the first direction (Z direction). The outer end surface 46 is farther from the electrode body 10 in the first direction (Z direction) than the edge portion 36.

[0041] A joint 50 is formed in the case 20. The joint 50 joins the edge 36 and the outer end surface 46. The joint 50 is formed by fusing together an edge 37 of the case body 30 before joining and an outer edge 49 of the sealing plate 40, which will be described later.

[0042] The thickness of sealing plate 40 in the first direction (Z direction) is preferably equal to or greater than the joining depth of joint 50 and equal to or greater than three times the first step H1 described below. This prevents joint 50 from melting into the inside of case body 30 when joining case body 30 and sealing plate 40, and ensures a sufficient joining area between case body 30 and sealing plate 40.

[0043] Hereinafter, a method for manufacturing the secondary battery 1 according to the first embodiment of the present technology will be described. Fig. 3 is a flowchart showing a method for manufacturing the secondary battery according to the first embodiment of the present technology. Fig. 4 is a perspective view showing a state in which an electrode body is inserted into a case body. Fig. 5 is a cross-sectional view showing a state in which the case body and the sealing plate according to the first embodiment of the present technology are positioned. Fig. 6 is a top view showing a position at which the case body and the sealing plate are temporarily joined. Fig. 7 is a cross-sectional view showing the positional relationship between the case body, the sealing plate, and the tilt angle of the laser when temporarily joining the case body and the sealing plate according to the first embodiment of the present technology. Fig. 8 is a cross-sectional view showing the tilt angle of the laser light when temporarily joining the case body and the sealing plate.

[0044] As shown in FIGS. 3 to 5, first, the electrode body 10, the case body 30, and the sealing plate 40 are prepared (step S10). The case body 30 has a pre-bonding edge 37 formed thereon. The pre-bonding edge 37 defines an opening 35 at one end in the first direction (Z direction). The pre-bonding edge 37 is a portion located at the end of the case body 30 in the first direction (Z direction) before the case body 30 and the sealing plate 40 are bonded together. The sealing plate 40 is formed into a shape that allows it to seal the opening 35.

[0045] Next, as shown in FIGS. 3 and 4, the electrode body 10 is housed in the case body 30 through the opening 35 (step S11).

[0046] 3 and 5, the case body 30 and the sealing plate 40 are positioned (step S12). Specifically, the case body 30 and the sealing plate 40 are positioned so that a first step H1 is provided between the edge portion 37 before joining and the outer end surface 46 of the sealing plate 40 in the first direction (Z direction).

[0047] The case body 30 is fixed to a jig (not shown). The sealing plate 40 is held by a holding device 2. The holding device 2 holds the sealing plate 40 by suctioning the outer end surface 46 of the sealing plate 40 using, for example, an air suction pad. When positioning the sealing plate 40, the position may be determined by a camera (not shown).

[0048] In the process of positioning the case body 30 and the sealing plate 40 in this embodiment (process S12), the outer end surface 46 is positioned farther from the electrode body 10 in the first direction (Z direction) than the edge portion 37 before joining.

[0049] 3 and 6, the case body 30 and the sealing plate 40 are partially joined together (step S13). That is, the case body 30 and the sealing plate 40 are temporarily joined together. The case body 30 and the sealing plate 40 are temporarily joined together by irradiating them with laser light.

[0050] The case body 30 and the sealing plate 40 are temporarily joined by a plurality of temporary joints 60. The plurality of temporary joints 60 are arranged at intervals from one another at the planned joining location of the case body 30 and the sealing plate 40. The temporary joints 60 are formed by moving the laser light approximately 1 mm from the sealing plate 40 side toward the case body 30 side (the direction of the arrow in FIG. 6).

[0051] Parameters to be considered when temporarily joining the case body 30 and the sealing plate 40 include the first step between the edge 37 and the outer end face 46 before joining, the maximum gap between the opening 35 and the outer end face 46, and the inclination angle of the optical axis of the laser light with respect to the first direction (Z direction).

[0052] 7, the first step H1 is a step before the case body 30 and the sealing plate 40 are joined together. Specifically, the first step H1 is a step that exists between the edge portion 37 and the outer end surface 46 of the sealing plate 40 before joining in the first direction (Z direction).

[0053] The reference position of the first step is the inner edge of the edge portion 37 before joining for the case body 30, and the outermost edge of the outer end face 46 for the sealing plate 40.

[0054] A gap may occur between the case body 30 and the sealing plate 40 due to dimensional tolerances of the case body 30 and the sealing plate 40, or deformation due to pressure when the case body 30 or the sealing plate 40 is held. The size of the gap varies in the circumferential direction in which the case body 30 and the sealing plate 40 are joined. As shown in FIG. 7 , the maximum gap between the opening 35 and the outer end surface 46 in a second direction (the Y direction in the cross section shown in FIG. 7 ) perpendicular to the first direction is defined as L.

[0055] The reference position of the maximum gap L is the inner end of the edge portion 37 before joining for the case body 30, and the outermost edge of the outer end face 46 for the sealing plate 40, similar to the reference position of the first step H1.

[0056] 7 and 8, a laser oscillator 3 oscillates a laser beam 4. The laser beam 4 is tilted with respect to a first direction (Z direction). The tilt angle of an optical axis A of the laser beam 4 with respect to the first direction is defined as θ.

[0057] 8, the direction in which the optical axis A extends (DR1 direction) is parallel to a line segment connecting the center of the width of the laser beam 4 immediately after being emitted from the laser oscillator 3 and the center of the width of the laser beam 4 at the irradiation position of the edge portion 37 or the outer end face 46. The tilt angle θ is the tilt angle of the direction in which the optical axis A extends (DR1 direction) with respect to the first direction (Z direction). In this embodiment, the optical axis A of the laser beam 4 is tilted from the sealing plate 40 side toward the joining position of the edge portion 37 or the outer end face 46.

[0058] 7, in the present embodiment, outer end surface 46 has a main surface portion 47, a recessed portion 48, and an outer edge portion 49. Main surface portion 47 occupies most of outer end surface 46. Recessed portion 48 is formed on the outer periphery of main surface portion 47, thereby separating main surface portion 47 from outer edge portion 49. Temporary bond portion 60 is formed by fusing together pre-bonded edge portion 37 of case body 30 and outer edge portion 49 of sealing plate 40.

[0059] By providing the recesses 48, heat generated by the recesses 48 on the outer edge portion 49 side is less likely to escape to the main surface portion 47 side, making it easier to concentrate the heat of the laser light 4 on the outer edge portion 49 and melt the outer edge portion 49. If the first step H1 is made large, even if the outer edge portion 49 is farther away from the focus of the laser light 4, the heat of the laser light 4 is more likely to concentrate on the outer edge portion 49, making it easier to melt the outer edge portion 49. This makes it easier to form the temporary bonded portion 60.

[0060] When joining a portion of the case body 30 and the sealing plate 40, laser light 4, whose optical axis A is tilted at an angle equal to or greater than the value of θ that satisfies the relationship tan θ = L / H1, is irradiated onto the edge portion 37 and the outer end face 46 before joining, thereby joining the portion of the case body 30 and the sealing plate 40. After being irradiated onto the edge portion 37 and the outer end face 46, the laser light 4 is reflected to the outside of the case body 30.

[0061] The inclination angle θ in this embodiment indicates the angle at which the laser beam 4, when irradiated from the end P1 of the outer edge 49 toward the pre-bonded edge 37, strikes the innermost end P2 of the edge 37. Therefore, if the inclination angle θ is a value greater than θ that satisfies tan θ=L / H1, the laser beam 4 will be irradiated from the end P1 of the outer edge 49 of the sealing plate 40 to a position outside the innermost end P2 of the edge 37, and the laser beam 4 will not be directed toward the maximum gap L.

[0062] In the process of joining a portion of case body 30 and sealing plate 40 of the present embodiment, step H1 is, for example, 0.3 mm or more and 1.4 mm or less. Maximum gap L is, for example, 0.05 mm or more and 0.2 mm or less. Inclination angle θ is, for example, 2° or more and 10° or less, and satisfies the relationship tan θ=L / H1.

[0063] Next, the entire periphery of the case body 30 and the sealing plate 40 are joined (step S14). That is, the case body 30 and the sealing plate 40 are finally joined. The case body 30 and the sealing plate 40 are finally joined by irradiating them with laser light 4. By finally joining the case body 30 and the sealing plate 40, the opening 35 is sealed by the sealing plate 40.

[0064] The conditions for this joining are that the beam diameter of the laser beam 4 is, for example, 0.8 mm or more and 1.0 mm or less at the positions where the laser beam 4 is irradiated onto the edge portion 36 and the outer end face 46. The output of the laser beam 4 is, for example, 6000 W. The moving speed of the laser beam 4 during joining is, for example, 300 mm / s. The tilt angle θ is, for example, 0°.

[0065] Here, the temporary joining of the case body and the sealing plate in the secondary battery according to the comparative example will be described. Fig. 9 is a cross-sectional view showing the positional relationship between the case body, the sealing plate, and the tilt angle of the laser when the case body and the sealing plate are temporarily joined together in the comparative example.

[0066] As shown in FIG. 9, in the manufacturing method of the secondary battery 9 according to the comparative example, the case body 30 and the sealing plate 90 are positioned so that the edge portion 37 before joining and the outer end surface 96 of the sealing plate 90 are in approximately the same position in the first direction (Z direction).

[0067] In the temporary joining of the case body 30 and the sealing plate 90 according to the comparative example, the laser beam 4 is irradiated at the same inclination angle θ as in the first embodiment. The laser beam 4 penetrates into the inside of the case body 30 from the maximum gap L between the case body 30 and the sealing plate 90. In other words, laser beam leakage occurs in the temporary joining of the case body 30 and the sealing plate 90 according to the comparative example. When laser beam leakage occurs in the case body 30, the electrode body 10 is damaged by being irradiated with the laser beam 4. In this comparative example, the separator of the electrode body 10 is damaged.

[0068] On the other hand, as shown in FIG. 7 , in the secondary battery 1 according to the first embodiment, a first step H1 is provided in the temporary joining. By providing the first step H1, the outer end surface 46 of the sealing plate 40 blocks the path through which the laser light 4 inclined at the inclination angle θ enters the interior of the case body 30. This makes it possible to prevent the laser light 4 from entering the interior of the case body 30. That is, in the temporary joining of the case body 30 and the sealing plate 40 according to the present embodiment, laser leakage can be prevented. As a result, damage to the electrode body 10 is suppressed. In this comparative example, damage to the separator of the electrode body 10 is suppressed.

[0069] A test was conducted to confirm that the configuration of the secondary battery 1 according to the present embodiment described above suppresses the occurrence of laser leakage into the inside of the case body 30. Fig. 10 is a graph showing the test results for confirming the occurrence of laser leakage when joining the case body and the sealing plate based on the correlation between the first step, the maximum gap, and the tilt angle of the laser.

[0070] As test conditions, the beam diameter of the laser light 4 was 0.6 mm at the position where the laser light 4 irradiated the edge portion 36 and the outer end surface 46. The output of the laser light 4 was 3000 W. The movement speed of the laser light 4 during joining was 150 mm / s. The tilt angle θ was 0° or more and 8° or less. The tilt angle θ was calculated by adjusting the target position. The first step height H1 was 0 mm or more and 1 mm or less. The maximum gap L was 0.1 mm. The maximum gap L was estimated from the manufacturing tolerances of the case body 30 and the sealing plate 40. The maximum gap L was formed by inserting a shim between the case body 30 and the sealing plate 40.

[0071] Tests were conducted by setting various first step heights H1 and inclination angles θ. In test T1, laser leakage occurred when the first step height H1 was 0.5 mm and the inclination angle θ was 8°. The occurrence of laser leakage is indicated by an "x". Similarly, laser leakage also occurred in tests T2 to T6.

[0072] On the other hand, in test T7, when the first step height H1 was 0.8 mm and the inclination angle θ was 8°, no laser leakage occurred. The absence of laser leakage is indicated by "○". In test T8, no laser leakage occurred either.

[0073] The relationship between the above test results and the curve C1 shown in Figure 10 was confirmed. The curve C1 shows tanθ=0.1 / H1, which is obtained by substituting L=0.1 into the formula tanθ=L / H1.

[0074] The region where the angle is less than the numerical value of θ that satisfies the relationship tanθ=0.1 / H1 is region R1, indicated by tanθ<0.1 / H1. In tests T1 to T6, which fall within region R1, laser leakage occurred. In addition, the region where the angle is greater than the numerical value of θ that satisfies the relationship tanθ=0.1 / H1 is region R2, indicated by tanθ>0.1 / H1. In tests T7 and T8, which fall within region R2, laser leakage did not occur. In this way, it was confirmed that the occurrence of laser leakage changes with curve C1 as the boundary line.

[0075] FIG. 11 is a graph showing the region where laser leakage does not occur when joining the case body and the sealing plate, based on the correlation between the laser irradiation angle and the first step for each gap between the case body and the sealing plate.

[0076] As shown in Figure 11, curve C1 indicates tan θ = 0.1 / H1 when the maximum gap is 0.1 mm, curve C2 indicates tan θ = 0.05 / H1 when the maximum gap is 0.05 mm, and curve C3 indicates tan θ = 0.2 / H1 when the maximum gap is 0.2 mm.

[0077] In addition to the region R2, the region of angles greater than or equal to tan θ=0.05 / H1 is region R3, where tan θ>0.05 / H1. The region of angles greater than or equal to tan θ=0.2 / H1 is region R4, where tan θ>0.2 / H1.

[0078] When the maximum gap is 0.05 mm, the occurrence of laser voids is suppressed under the conditions in region R3. When the maximum gap is 0.2 mm, the occurrence of laser voids is suppressed under the conditions in region R4.

[0079] By setting the first step height H1, the maximum gap L between the case body 30 and the sealing plate 40, and the tilt angle θ of the optical axis A of the laser light 4 so as to satisfy tan θ=L / H, and irradiating the laser light 4 at an angle equal to or greater than the tilt angle θ, laser leakage is suppressed during the temporary bonding of the case body 30 and the sealing plate 40. As the maximum gap L increases, the first step height H1 and the tilt angle θ are increased, thereby suppressing laser leakage.

[0080] Next, the correlation between the first step H1 before joining the case body 30 and the sealing plate 40 and the second step after joining will be described. Fig. 12 is a cross-sectional view showing the configuration of the joining portion between the case body and the sealing plate in embodiment 1 of the present technology. Fig. 13 is a graph showing the correlation between the first step and the second step.

[0081] 12, a second step H2 is provided in the case 20 after temporary joining and final joining. The second step H2 is a step that is located in the first direction (Z direction) between the end of the joint 50 and the outer end surface 46. The reference position of the second step H2 is the end of the joint 50 in the first direction for the joint 50, and is the main surface 47 that constitutes the outer end surface 46 for the sealing plate 40.

[0082] For example, when the first step is set to 0.8 mm and temporary joining is performed, and then the entire circumference is finally joined, the second step H2 becomes -0.3 mm, with the outer end face 46 as the reference and the direction downward being negative.

[0083] As shown in Fig. 13, the second step H2 was confirmed for various first step H1. In Fig. 13, the confirmation results of the second step H2 for various first step H1 are indicated by "○". The correlation between the first step H1 and the second step H2 was an approximate straight line of y = -0.44x, where x is the first step and y is the second step.

[0084] In the present embodiment, the second step H2, when expressed as an absolute value, is 0.23 mm or more and is 1 / 7 or less of the thickness of the sealing plate 40 in the first direction (Z direction).

[0085] The range of the second step H2 is desirably determined by the thickness of the sealing plate 40. As described above, the test results show that the first step (x) and the second step (y) have the relationship y=-0.44x.

[0086] When the thickness of the sealing plate is t, it is desirable that the thickness (t) of the sealing plate be at least three times the first step (x). Therefore, x = (1 / 3)t. Substituting this equation into y = -0.44x, we obtain y = -0.44x × ((1 / 3)t) ≒ -(1 / 7)t.

[0087] When the second step height H2 is expressed as an absolute value, the upper limit of the second step height H2 varies depending on the thickness of the sealing plate. For this reason, the upper limit of the second step height H2 is expressed as y=(1 / 7)t, which is the absolute value of the relational expression y=-(1 / 7)t between the second step height (y) and the sealing plate thickness (t).

[0088] When expressing second step height H2 as an absolute value, the lower limit of second step height H2 is calculated from the minimum thickness of sealing plate 40. Since the bonding depth of bonding portion 50 is 1.6 mm, sealing plate 40 must be at least 1.6 mm thick. When the sealing plate thickness is 1.6 mm, substituting t=1.6 into y=-(1 / 7)t, which is the relationship between second step height (y) and sealing plate thickness (t), yields y=-0.23. Therefore, the lower limit of second step height H2 is y=0.23, which is the absolute value of y=-0.23.

[0089] In the method for manufacturing the secondary battery 1 according to the first embodiment of the present technology, when the case body 30 and the sealing plate 40 are temporarily joined together, a first step H1 is provided at the joining position of the case body 30 and the sealing plate 40, and the optical axis A of the laser light 4 is tilted at an inclination angle θ. This allows the first step H1 to block the laser light 4 that enters the inside of the case body 30 through the maximum gap L, thereby preventing laser leakage when the case body 30 and the sealing plate 40 are temporarily joined together. As a result, it is possible to improve the robustness (resistance to external influences such as the gap) of the temporary joining when a gap occurs between the case body 30 and the sealing plate 40.

[0090] In the manufacturing method of the secondary battery 1 according to the first embodiment of the present technology, even if the maximum gap L between the case body 30 and the sealing plate 40 varies, by setting the first step H1 and the inclination angle θ of the optical axis A of the laser light 4 to match the size of the maximum gap L, it is possible to suppress laser leakage when temporarily joining the case body 30 and the sealing plate 40.

[0091] In the method for manufacturing the secondary battery 1 according to the first embodiment of the present technology, the laser beam 4 is moved approximately 1 mm from the sealing plate 40 side toward the case body 30 side (the direction of the arrow in FIG. 6 ), thereby forming the temporary bond 60. This prevents the laser beam 4 from entering the gap between the case body 30 and the sealing plate 40, while allowing the laser beam 4 to be sufficiently irradiated onto the edge 37 and outer edge 49 before bonding, ensuring a sufficient bonding depth, thereby enabling the case body 30 and the sealing plate 40 to be reliably temporarily bonded together.

[0092] In the manufacturing method for the secondary battery 1 and the secondary battery 1 according to the first embodiment of the present technology, the outer end surface 46 is disposed in a position in the first direction (Z direction) farther from the electrode body 10 than the edge portion 37 before joining or the edge portion 36 after joining, thereby increasing the internal space of the case body 30. This increases the volume occupied by the electrode body 10 inside the case body 30, and improves the performance of the secondary battery 1.

[0093] In the secondary battery 1 according to the first embodiment of the present technology, a first step H1 of 0.23 mm or more and 1 / 7 or less of the thickness of the sealing plate 40 is provided between the end of the joint 50 between the case body 30 and the sealing plate 40 and the outer end face 46 of the sealing plate 40, thereby making it possible to suppress laser voids when temporarily joining the case body 30 and the sealing plate 40. This in turn makes it possible to suppress damage to the separator of the electrode assembly 10.

[0094] (Embodiment 2) Hereinafter, a description will be given of a method for manufacturing a secondary battery and a secondary battery according to embodiment 2 of the present technology. The method for manufacturing a secondary battery and a secondary battery according to embodiment 2 of the present technology differ from the method for manufacturing secondary battery 1 and secondary battery 1 according to embodiment 1 of the present technology in the configuration of the sealing plate and the direction of laser light irradiation, and therefore, the description of the configuration that is similar to the method for manufacturing secondary battery 1 and secondary battery 1 according to embodiment 1 of the present technology will not be repeated.

[0095] FIG. 14 is a cross-sectional view showing the positional relationship between the case body, the sealing plate, and the tilt angle of the laser when the case body and the sealing plate are temporarily joined together according to the second embodiment of the present technology.

[0096] 14, when the case body 30 and the sealing plate 40A are temporarily joined together in the second embodiment of the present technology, the sealing plate 40A is positioned closer to the electrode body 10 than the pre-joining edge 37 of the case body 30. The laser light 4A is inclined from the case body 30 side toward the joining position of the edge 37 or the outer end face 46A.

[0097] In the manufacturing method for a secondary battery and the secondary battery according to the second embodiment of the present technology, when the Z direction is the height direction, the position of the sealing plate 40A is lowered, and the height of the secondary battery can be reduced.

[0098] (Embodiment 3) Hereinafter, a secondary battery according to embodiment 3 of the present technology will be described. The secondary battery according to embodiment 3 of the present technology differs from secondary battery 1 according to embodiment 1 of the present technology in the configuration of the case body and the method of positioning the case body and the sealing plate, and therefore, the description of the configuration that is the same as secondary battery 1 according to embodiment 1 of the present technology will not be repeated.

[0099] Fig. 15 is a cross-sectional view showing a state in which a case body and a sealing plate are positioned according to embodiment 3 of the present technology. Fig. 16 is a flowchart showing a method for manufacturing a secondary battery according to embodiment 3 of the present technology.

[0100] 15, the edge portion 37B before joining according to this embodiment includes a first portion 38B and a second portion 39B. The first portion 38B is located on the outer periphery side of the case body 30B. The second portion 39B is located on the inner periphery side of the case body 30B. A third step portion H3 is formed between the first portion 38B and the second portion 39B. As a result, the first portion 38B is provided so as to protrude further outward from the case body 30B in the first direction (Z direction) than the second portion 39B.

[0101] 16, the electrode body 10, the case body 30, and the sealing plate 40B are prepared (step S30). A first portion 38B and a second portion 39B are provided in the case body 30B (step S31). Thereafter, the electrode body 10 is housed in the case body 30B (step S32).

[0102] As shown in FIGS. 15 and 16, in the step of positioning the case body 30B and the sealing plate 40B (step S33), the second portion 39B and the inner end surface 45B of the sealing plate 40B abut against each other in the first direction (Z direction).

[0103] With the second portion 39B and the sealing plate 40B in contact with each other in the first direction (Z direction), the pre-joined edge portion 37B and the outer end surface 46B are temporarily joined and permanently joined (steps S34 and S35).

[0104] In the manufacturing method for a secondary battery and the secondary battery according to the third embodiment of the present technology, by providing a first portion 38B that protrudes further than the second portion 39B on the edge 37B before joining, the case body 30B and the sealing plate 40B can be positioned so that the second portion 39B and the sealing plate 40B abut in the first direction (Z direction). This allows the case body 30B and the sealing plate 40B to be positioned without using a holding device for holding the sealing plate 40B. Furthermore, because the first step H1 can be provided without being affected by operational variations in the manufacturing equipment, the case body 30B and the sealing plate 40B can be stably positioned.

[0105] In the manufacturing method of the secondary battery according to the third embodiment of the present technology, the formation of the third step portion H3 facilitates adhesion between the second portion 39B and the inner end surface 45B of the sealing plate 40B, thereby suppressing laser leakage.

[0106] Note that the first step in each of the above-described embodiments does not refer to a step that occurs due to manufacturing tolerances of the case body and the sealing plate when the design value is a state in which there is no step between the case body and the sealing plate.

[0107] Furthermore, in the above-described embodiments, the laser beam is not tilted when the case body and the sealing plate are permanently joined. By positioning the starting point of the laser beam for permanent joining at the temporary joined location, laser beam leakage at the start of joining is prevented. When the entire circumference is subsequently joined, the joined locations gradually melt, blocking the laser beam at the joined locations themselves, preventing laser beam leakage.

[0108] Although the embodiments of the present technology have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0109] 1, 9 Secondary battery, 2 Holding device, 3 Laser oscillator, 4, 4A Laser light, 10 Electrode body, 20 Case, 30, 30B Case body, 31 Bottom surface, 32 First side surface, 33 Second side surface, 34 Third side surface, 35 Opening, 36, 36B Edge portion after joining, 37 Edge portion before joining, 38B First portion, 39B Second portion, 40, 40A, 40B, 90 Sealing plate, 41 Electrode terminal, 42 Positive electrode terminal, 43 Negative electrode terminal, 45 Inner end surface, 46, 46A, 46B, 96 Outer end surface, 47 Main surface, 48 Recess, 49 Outer edge, 50 Joint, 60 Temporary joint, A Optical axis, C1, C2, C3 Curve, H1 First step, H2 Second step, H3 Third step, L maximum gap.

Claims

1. a step of preparing an electrode body, a case body having an edge portion defining an opening at one end in a first direction, and a sealing plate capable of sealing the opening; a step of accommodating the electrode body in the case body through the opening; a step of positioning the case body and the sealing plate so that a step is provided between the edge portion and an outer end face of the sealing plate that is located on the opposite side to an inner end face of the sealing plate that faces the electrode body in the first direction; When the step is H1, the maximum gap between the opening and the outer end surface in a second direction perpendicular to the first direction is L, and the tilt angle of the optical axis of the laser light with respect to the first direction is θ, irradiating the edge and the outer end surface with the laser light, the optical axis of which is tilted at an angle equal to or greater than the value of θ that satisfies the relationship tan θ = L / H1, to join a portion of the case body and the sealing plate.

2. In the step of joining a portion of the case body and the sealing plate, The step H1 is equal to or greater than 0.3 mm and equal to or less than 1.4 mm, The maximum gap L is 0.05 mm or more and 0.2 mm or less, The method for manufacturing a secondary battery according to claim 1 , wherein the inclination angle θ is equal to or greater than 2° and equal to or less than 10°, and satisfies the relationship tan θ=L / H1.

3. In the step of positioning the case body and the sealing plate, 3. The method for manufacturing a secondary battery according to claim 1, wherein the outer end surface is disposed at a position farther from the electrode body than the edge portion in the first direction.

4. The edge portion includes a first portion located on an outer circumferential side and a second portion located on an inner circumferential side, the first portion is provided so as to protrude further outward from the case body than the second portion in the first direction, 3 . The method for manufacturing a secondary battery according to claim 1 , wherein in the step of positioning the case body and the sealing plate, the second portion and the sealing plate abut against each other in the first direction.

5. An electrode body; a case body that houses the electrode body and has an edge that defines an opening at one end in a first direction; a sealing plate including an inner end surface facing the electrode body and an outer end surface located on the opposite side to the inner end surface, and sealing the opening, The opening has a shape that allows the electrode body to be inserted therethrough, a joint portion is formed to join the edge portion and the outer end surface; a step is provided between an end of the joint portion and the outer end surface in the first direction, the step is 0.23 mm or more and 1 / 7 or less of the thickness of the sealing plate in the first direction.

6. The secondary battery according to claim 5 , wherein the outer end surface is farther from the electrode body in the first direction than the edge portion.

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