JP2016110859A - Current cutoff device and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current cutoff device capable of reducing the impact of the welding, of the peripheral portion of a reversal plate and the step of a rivet in the current cutoff device, on the reversal operation of the reversal plate, without increasing the laser output, and to provide a secondary battery.SOLUTION: In a current cutoff device and a secondary battery, a laser beam is irradiated in a direction crossing a reversal plate side tapered surface 33t and a rivet side tapered surface 45t, and a melting mark WR formed in a reversal plate 30 and a step 45 is formed to extend from the reversal plate side tapered surface 33t toward the rivet side tapered surface 45t (arrow LD direction).SELECTED DRAWING: Figure 8

Description

  The present invention relates to a current interrupting device used for a secondary battery and a structure of the secondary battery.

  A typical secondary battery includes a current interrupt device. The current interrupting device includes a current collecting terminal electrically connected to the battery element, an inversion plate joined to the current collecting terminal, an external terminal electrically connected to the inversion plate, and the like. The reversing plate receives the internal pressure, and the reversing plate is reversely deformed in a direction away from the current collecting terminal, whereby the conduction between the battery element and the external terminal is interrupted.

  In Japanese Patent Application Laid-Open No. 2014-086176 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2013-093208 (Patent Document 2), an inversion plate is disposed at a step portion formed on a rivet, and an edge portion of the inversion plate is disclosed. A technique is disclosed in which the entire circumference of the rivet and the step portion of the rivet are butted against each other.

JP 2014-086176 A JP 2013-093208 A

  The entire circumference of the peripheral part of the reversing plate and the step part of the rivet are joined by welding, but it is reversed due to the clearance during insertion, the inner diameter error of the step part of the rivet, and the outer diameter error of the reversing plate. A slight gap (clearance) is formed between the peripheral portion of the plate and the step portion of the rivet.

  Usually, welding irradiates a laser between the step part of a rivet and the peripheral part of an inversion board. In order to secure sufficient melt deposition to fill the gap (clearance), the rivet and the reverse plate are greatly welded. However, when the amount of melting in the welding of the rivet and the reverse plate is increased, the shrinkage after cooling increases, and the height of the reverse plate changes. As a result, the operating pressure of the reversing plate changes.

  On the other hand, in order to prevent the above-mentioned gap (clearance) from being generated, it is conceivable to press-fit the reverse plate into the step portion of the rivet. However, there is a possibility that pressure is applied to the reversing plate and the reversing plate is deformed. When deformation occurs in the reverse plate, the operating pressure of the reverse plate changes. Therefore, a method of performing welding in a state where a minimum gap (clearance) is formed between the edge portion of the reversing plate and the step portion of the rivet can be considered.

  However, as described above, even when welding is performed, there is a possibility that the operating pressure of the reversing plate may be adversely affected. It is conceivable that the bottom of the part and the reversing plate are overlapped and welded.

  When the welding position is moved to the inner peripheral side in this way, a thermal stress is locally generated at a position that is a starting point of deformation of the reversing plate (a position where the reversing plate is not supported by the bottom of the step portion of the rivet). As a result, the reverse plate softens and the operating pressure of the reverse plate changes.

  In addition, since the energy for penetrating the laser reversal plate increases, the amount of heat (output) of laser welding increases, and there is a concern about the adverse effects of heat transfer to the gasket used to improve the airtightness of the current interrupting device. The

  Furthermore, if it is considered that the rivet and the reversing plate are fixed at another part of the reversing plate, the effect on the reversing operation of the reversing plate is considered to increase. It is possible to enlarge it.

  The present invention has been made in view of the above problems, and in the welding of the peripheral portion of the reversing plate of the current interrupting device and the step portion of the rivet, the reversing operation of the reversing plate is performed without increasing the laser output. An object of the present invention is to provide a current interrupting device and a secondary battery that can reduce the influence on the battery.

  In the current interrupting device and the secondary battery, when the internal pressure of the exterior body containing the battery element rises, the current flow between the battery element and the external terminal provided outside the exterior body is interrupted. A current reversing device that reverses when the internal pressure of the exterior body rises, thereby reversing the electrical connection between the battery element and the external terminal. Are connected to each other, and a welding laser beam is irradiated to the entire circumference at a rivet having an annular step portion on which the peripheral portion of the reversing plate is placed, and a butt portion between the step portion and the peripheral portion. And a melted mark that has been welded all around.

  In a cross-sectional view including the center point of the reversing plate, the peripheral portion of the reversing plate extends from the outer peripheral end surface of the reversing plate to the bottom surface, and approaches the bottom surface of the stepped portion toward the center point side. A taper surface is provided, and the step portion of the rivet has a rivet side extending substantially parallel to the reversing plate side taper surface from a standing wall facing the outer peripheral end surface of the reversing plate toward the bottom surface of the step portion. A taper surface is provided, and the laser beam is irradiated in a direction intersecting the reverse plate side taper surface and the rivet side taper surface, whereby the melt mark formed on the reverse plate and the step portion. Is formed to extend from the reverse plate side tapered surface toward the rivet side tapered surface.

  As described above, according to the current interrupt device and the secondary battery, the melt marks formed on the reversing plate and the stepped portion are formed to extend from the reversing plate side tapered surface toward the rivet side tapered surface. . This is formed by irradiating the laser beam in a direction intersecting the reverse plate side taper surface and the rivet side taper surface, but by providing the reverse plate side taper surface at the peripheral edge of the reverse plate, The plate thickness in the normal direction with respect to the reverse plate side taper surface is thinner than the plate thickness of the reverse plate.

  The step portion of the rivet is provided with a rivet side taper surface extending substantially parallel to the reversal plate side taper surface from the standing wall facing the outer peripheral end surface of the reversal plate toward the bottom surface of the step portion. Thereby, the inversion board side taper surface and the rivet side taper surface will be in the state which opposes a fixed clearance gap in the full length.

  As a result, when the reverse plate side taper surface and the rivet side taper surface are joined by welding using a laser beam, the thickness is smaller than the original thickness of the reverse plate in the direction intersecting the reverse plate side taper surface. Therefore, the output of the laser beam penetrating the reverse plate side taper surface of the reverse plate can be made smaller than before, and the melting amount of the reverse plate and the rivet can be reduced. Thereby, the bad influence to the inversion board by the influence of the heat | fever at the time of laser beam irradiation can be made small.

  In addition, since the reverse plate side taper surface and the rivet side taper surface are inclined, the melted portion of the reverse plate and the rivet flows downward along the rivet side taper surface during welding using a laser beam. It becomes easy. As a result, the melted portion fills the gap between the reverse plate side taper surface and the rivet side taper surface and also fills the gap located below, so that the melted member is used effectively, and the reverse plate And the rivet can be joined better.

  According to the current interrupting device and the secondary battery, in welding the peripheral portion of the reversing plate of the current interrupting device and the step portion of the rivet, the influence on the reversing operation of the reversing plate without increasing the laser output. It is possible to provide a current interrupt device and a secondary battery that can reduce the size of the battery.

It is a top view which shows the secondary battery in embodiment. It is sectional drawing which shows the secondary battery in embodiment. It is arrow sectional drawing along the III-III line in FIG. FIG. 4 is an exploded perspective view corresponding to FIG. 3. It is a disassembled perspective sectional view of the inversion board and rivet in an embodiment. It is a perspective view which shows the welding state to the rivet of the inversion board in embodiment. It is a partial expanded sectional view of the peripheral part of an inversion board and the level difference part of a rivet before welding of an embodiment. It is a partial expanded sectional view of the peripheral part of an inversion board and the rivet after welding of an embodiment. It is a partial expanded sectional view of the inversion board and rivet of the peripheral part of an inversion board which shows the subject at the time of welding in related technology. It is a partial expanded sectional view of the inversion board and rivet of the peripheral part of an inversion board which shows the subject at the time of welding in related technology. It is a figure which shows the beam angle, the output (W), and the inversion board working pressure ((sigma)) in the comparative example 1 to the comparative example 4 and the Example 1 to Example 5. FIG.

  Hereinafter, embodiments will be described with reference to the drawings. When referring to the number, amount, etc., the scope of the present invention is not necessarily limited to the number, amount, etc., unless otherwise specified. The same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated.

  With reference to FIGS. 1-4, the secondary battery 100 in this Embodiment is demonstrated. 1 is a plan view showing the secondary battery 100, FIG. 2 is a cross-sectional view showing the secondary battery 100, FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1, and FIG. FIG. 4 is an exploded perspective view corresponding to FIG. 3.

  Referring to FIGS. 1 and 2, secondary battery 100 includes an exterior body 10, an electrode body 13, a positive external terminal 20 and a current collecting terminal 21, and a negative external terminal 24 and a current collecting terminal 25. . The exterior body 10 includes a bottomed cylindrical accommodating portion 11 and a sealing plate 12. The exterior body 10 accommodates the electrode body 13 (battery element) inside. The external terminals 20 and 24 are attached to the sealing plate 12. The electrode body 13 has a positive electrode core body, a negative electrode core body, and a separator (all not shown), and the positive electrode core body and the negative electrode core body are wound through the separator. A positive electrode core exposed portion 14 and a negative electrode core exposed portion 15 are respectively provided at both ends of the electrode body 13.

  The positive electrode core exposed portion 14 is electrically connected to the external terminal 20 via the current collecting terminal 21 and a current interrupt device 1 described later. The negative electrode core exposed portion 15 is electrically connected to the external terminal 24 via the current collecting terminal 25 and the current interrupting device 1. Since the current interrupting device 1 for the positive electrode and the current interrupting device 1 for the negative electrode have the same configuration, the details thereof will be described below with a focus on the current interrupting device 1 for the positive electrode.

  With reference to FIG. 3 and FIG. 4, the structure and manufacturing method of a current interrupting device will be described. For convenience of explanation, only the current collecting terminal 21, the reversing plate 30 (also referred to as a diaphragm), and the rivet 40 are illustrated in FIG. In addition to the current collecting terminal 21, gaskets 16, 17, 18, a conductive plate 19, a reversing plate 30, and a rivet 40 are provided in the vicinity of the sealing plate 12 and the external terminal 20 (see FIGS. 1 and 2). .

  A through hole 12H is formed in the sealing plate 12. The gaskets 17 and 18 are disposed inside the sealing plate 12 (inside the exterior body 10). The gasket 16 and the conductive plate 19 are disposed outside the sealing plate 12 (outside of the exterior body 10). The rivet 40 is caulked while being inserted into the through-hole 12 </ b> H, and fixes the conductive plate 19 and the gasket 16 to the sealing plate 12. In the state shown in FIG. 3, the current collecting terminal 21 is electrically connected to the external terminal 20 through the reversing plate 30, the rivet 40 and the conductive plate 19.

  The rivet 40 includes a caulking portion 41, a small diameter portion 42, a connection portion 43, a large diameter portion 44, and a step portion 45. The caulking portion 41 is formed on the opposite side of the small diameter portion 42 from the connection portion 43. The caulking portion 41 is formed by caulking the end portion side of the small diameter portion 42 after inserting the small diameter portion 42 into the through hole 12H. The step portion 45 is a portion formed outside the large-diameter portion 44 and has an annular shape as a whole. The step portion 45 includes a bottom surface 45b and a standing wall 45a rising from the bottom surface 45b. The detailed shape of the step 45 will be described later. The space inside the connecting portion 43, the large diameter portion 44, and the stepped portion 45 allows the reversing plate 30 described later to be reversed.

  The inversion plate 30 includes a top surface portion 31 (inversion portion), an inclined portion 32, and a peripheral edge portion 33, and is made of an aluminum alloy or the like. The plate thickness is about 0.1 mm to 0.3 mm. The top surface portion 31 has a circular shape. The inclined portion 32 has an annular shape that surrounds the periphery of the top surface portion 31. The peripheral portion 33 of the reversing plate 30 is formed outside the inclined portion 32 and has an annular shape. In the manufacturing process, the reversing plate 30 is fixed to the rivet 40 by welding the peripheral portion 33 of the reversing plate 30 and the stepped portion 45 of the rivet 40 to each other. The end face shape of the peripheral edge portion 33 will be described in detail later together with the step portion 45 of the rivet 40.

  The current collecting terminal 21 includes flat plate portions 21L and 21R, a thick portion 22, a thin portion 23, a through hole 23H, and an annular groove 23G, and is made of an aluminum alloy or the like. The flat plate portions 21L and 21R are welded to the positive electrode core exposed portion 14. The current collecting terminal 21 is electrically connected to the electrode body 13 by the welding. The top surface portion 31 of the reversing plate 30 is joined to the thin portion 23 by laser welding. The through hole 23H and the annular groove 23G are both provided in the thin portion 23.

  Next, fixation of the reversing plate 30 to the rivet 40 will be described with reference to FIGS. 5 and 6. FIG. 5 is an exploded perspective sectional view of the reversing plate 30 and the rivet 40, and FIG. 6 is a perspective view showing a welding state of the reversing plate 30 to the rivet 40.

  The rivet 40 is provided with an annular step 45 on which the peripheral edge 33 of the reversing plate 30 is placed. The height of the standing wall 45 a in the stepped portion 45 is approximately the same as the height of the peripheral edge portion 33 of the reversing plate 30. Further, the radial width of the standing wall 45 a in the stepped portion 45 is substantially the same as the radial width of the peripheral edge portion 33 of the reversing plate 30.

  In the manufacturing process, as shown in FIG. 6, the peripheral portion 33 of the reversing plate 30 is placed on the step portion 45 of the rivet 40, so that a butt portion is provided between the step portion 45 and the peripheral portion 33 over the entire circumference. It is formed. Next, temporary fixing welding (melting marks 50) is performed on a plurality of selected regions.

  Next, in the butt portion between the step portion 45 of the rivet 40 and the peripheral edge portion 33 of the reversing plate 30, the entire circumference is scanned while irradiating the welding laser beam (LB1) to perform the entire circumference welding. As a result, a melting mark 60 is formed on the entire circumference of the butt portion between the step 45 and the peripheral edge 33.

  Next, the shape of the peripheral edge portion 33 of the reversing plate 30 and the stepped portion 45 of the rivet 40 in the present embodiment will be described with reference to FIG. FIG. 7 is a partially enlarged cross-sectional view of the peripheral portion 33 of the reversing plate 30 and the stepped portion 45 of the rivet 40 before welding, and is a cross-sectional view including the center point CP (see FIG. 6) of the reversing plate 30.

  On the peripheral edge 33 of the reversing plate 30, a reversing plate-side taper surface 33t is provided that extends from the outer peripheral end surface 33a of the reversing plate 30 to the bottom surface 33b and approaches the bottom surface 45b of the stepped portion 45 toward the center point CP side. The intersecting angle (θ1) between the reversing plate-side tapered surface 33t of the reversing plate 30 and the bottom surface 33b of the reversing plate 30 is provided at an angle in the range of more than 90 ° and less than 180 °, but a preferable angle (θ1). Will be described in the examples described later.

  On the other hand, the step portion 45 of the rivet 40 extends substantially parallel to the reverse plate-side tapered surface 33t and the gap S from the standing wall 45a facing the outer peripheral end surface 33a of the reverse plate 30 toward the bottom surface 45b of the step portion 45. A rivet side tapered surface 45t is provided. The size of the gap S is preferably about 0.1 mm. The angle (θ2) at which the rivet-side tapered surface 45t and the bottom surface 45b of the stepped portion 45 intersect each other is set to an angle in the range of more than 90 ° and less than 180 °. As in the case of, it will be described in the embodiments described later.

  Next, with reference to FIG. 8, the melt mark WR by irradiation with the laser beam LB will be described. FIG. 8 is a partially enlarged cross-sectional view of the periphery of the reversing plate and the rivet after welding. The irradiation direction (seam welding) of the laser beam LB with which the reversing plate 30 is irradiated is irradiated in a direction intersecting with the reversing plate side taper surface 33t and the rivet side taper surface 45t. A conical surface-shaped melt mark WR formed on 34 extends from the reversing plate side taper surface 33t toward the rivet side taper surface 45t (in the direction of arrow LD in the figure).

  Referring to FIG. 7 again, regarding the irradiation angle (φ1) of the laser beam LB, the incident angle of the laser beam LB on the reverse plate-side tapered surface 33t is preferably 90 ° or more and 110 ° or less. Further, it is preferably 90 ° or more and 105 ° or less. This angle is in the range of 70 ° to 90 °, preferably 70 ° to 185 °, as an irradiation angle (φ2) with respect to the surface 33h of the peripheral portion 33 of the reversing plate 30.

  Here, with reference to FIG. 9 and FIG. 10, the subject at the time of welding in related technology is demonstrated. In FIG. 10, neither the outer peripheral end surface 33a of the reversing plate 30 nor the standing wall 45a of the stepped portion 45 is provided with a taper. In this case, the laser beam LB is irradiated between the outer peripheral end surface 33a and the standing wall 45a in order to fill a gap generated between the outer peripheral end surface 33a and the standing wall 45a.

  When the output of the laser beam LB is reduced in consideration of the influence of the heat of the laser beam LB, the melted portion does not reach the bottom surface 45b of the stepped portion 45, but remains in the melting between the outer peripheral end surface 33a and the standing wall 45a. It will be. As a result, the molten state becomes very unstable.

  On the other hand, when the output of the laser beam LB is increased in order to reach the bottom surface 45b of the stepped portion 45, the thermal influence on the reversing plate 30 and the gaskets 16 constituting the current interrupting device 1 The thermal influence on 17 and 18 cannot be ignored.

  On the other hand, as shown in FIG. 10, it is also conceivable that only the reversing plate 30 is provided with a reversing plate-side tapered surface 33t and the irradiation angle of the laser beam LB is inclined. In this case, since a large space is formed between the reversing plate side taper surface 33t and the standing wall 45a of the stepped portion 45, the peripheral portion 33 of the reversing plate 30 needs to be largely melted. It is necessary to increase the output of the beam LB.

  Referring to FIG. 8 again, in the present embodiment, the thickness in the normal direction with respect to the reverse plate side taper surface 33t is provided by providing the reverse plate side taper surface 33t at the peripheral edge portion 33 of the reverse plate 30. Is thinner than the thickness of the reversing plate 30. Further, the stepped portion 45 of the rivet 40 has a rivet-side tapered surface 45t extending substantially in parallel with the reversed plate-side tapered surface 33t from the standing wall 45a facing the outer peripheral end surface 33a of the reversed plate 30 toward the bottom surface of the stepped portion 45. Is provided. Thereby, the inversion board side taper surface 33t and the rivet side taper surface 45t will be in the state which opposes across the fixed clearance S in the full length.

  As a result, when the reversing plate side taper surface 33t and the rivet side taper surface 45t are joined by welding using the laser beam LB, the thickness (t1) is reversed in the direction intersecting the reversing plate side taper surface 33t. Since the thickness is smaller than the original thickness (t) of the plate 30, the output of the laser beam LB penetrating the reverse plate-side tapered surface 33t of the reverse plate 30 is made smaller than before, and the reverse plate 30 and the rivet 40 are melted. The amount can be reduced. Thereby, the bad influence to the inversion board 30 by the influence of the heat | fever at the time of irradiation of the laser beam LB can be made small.

  Further, since the reversing plate side taper surface 33t and the rivet side taper surface 45t are inclined, at the time of welding using the laser beam LB, the melting location of the reversing plate 30 and the rivet 40 is along the rivet side taper surface 45t. It becomes easy to flow downward (in the direction of arrow LF in the figure). As a result, the melted portion fills the gap between the reversing plate side taper surface 33t and the rivet side taper surface 45t and also fills the gap located below, so the melted member is effectively used. The reversal plate 30 and the rivet 40 can be joined better.

  In addition, since it is possible to improve the bonding between the reversing plate 30 and the rivet 40, it is not necessary to employ a configuration in which the reversing plate 30 is press-fitted into the rivet 40.

(Example)
Hereinafter, the laser beam irradiation angle, the output (W), and the reverse plate operating pressure variation (σ) in Examples 1 to 5 and Comparative Examples 1 to 5 will be described with reference to FIG. In this embodiment, an aluminum plate (A1050) having a thickness of 0.3 mm was used as the reversing plate 30. As the material of the rivet 40, the same aluminum plate (A1050) as the reversing plate 30 was used. As the laser beam LB, seam welding was performed.

  The comparative example 1 was implemented with the structure shown in FIG. Seam welding was performed by irradiating the laser beam LB to the gap (S = 0.1 mm) between the outer peripheral end surface 33a of the reversing plate 30 and the standing wall 45a of the stepped portion 45. As shown in FIG. 11, the output of the laser beam LB was 800 W. As a result, the reverse plate operating pressure variation (σ) was 0.051. Here, the reverse plate operating pressure variation (σ) is based on the result of measuring the operating pressure with respect to the 15 reverse plates 30. In order to perform stable welding, an output of 800 W was necessary. The minimum thickness after welding is secured about 0.2 mm to 0.3 mm, and there is no problem in strength. However, due to thermal shrinkage in the melted part, the value of the reverse plate working pressure variation (σ) is The numerical values were larger than those of the examples shown below.

  In Comparative Example 2, welding was performed with the configuration shown in FIG. Only the reverse plate 30 was provided with the reverse plate side taper surface 33t, and the laser beam LB was irradiated from above. The reverse plate side taper surface 33t was set to L = 0.3 mm and H = 0.2 mm. As the welding conditions, similarly to Comparative Example 1, an output of 800 W was required, and the value of the reverse plate operating pressure variation (σ) was 0.059.

  In Comparative Example 3, welding was performed with the configuration shown in FIG. However, the laser beam LB was irradiated from above. The reversing plate side taper surface 33t and the rivet side taper surface 45t are both L = 0.3 mm and H = 0.2 mm. Even when a tapered shape is adopted for the peripheral edge portion 33 of the reversing plate 30 and the stepped portion 45 of the rivet 40, the welding condition requires an output of 800 W as in Comparative Example 1, and the variation of the reversing plate working pressure varies. The value of (σ) was 0.062 equivalent to that of Comparative Example 1.

  Comparative Example 4 was performed with the configuration shown in FIG. Regarding the irradiation angle of the laser beam LB, the irradiation angle (φ2) with respect to the surface 33h of the peripheral portion 33 of the reversing plate 30 was set to 25 ° (see FIG. 7). Just by providing an inclination to the irradiation angle of the laser beam LB, the welding condition requires an output of 800 W as in Comparative Example 1, and the value of the reverse plate working pressure variation (σ) is the same as that in Comparative Example 1. It was equivalent to 0.058.

  In Example 1, welding was performed with the configuration shown in FIG. With respect to the irradiation angle (φ1) of the laser beam LB, the incident angle of the laser beam LB on the reversing plate side tapered surface 33t was set to 90 °. The reverse plate side taper surface 33t and the rivet side taper surface 45t are both L = 0.3 mm and H = 0.2 mm (taper angle 34 °).

  As a result, as welding conditions, welding was realized with an output of 500 W, and the value of the reverse plate operating pressure variation (σ) was 0.030 (see FIG. 11). By specifying the irradiation angle of the laser beam LB, the melting volume can be reduced, and the effect of reducing the shrinkage after cooling of the melted portion is to reduce the value of the reverse plate operating pressure variation (σ). It could be confirmed. When the incident angle with respect to the taper is increased, the plate thickness to be melted increases, so that the output increases. However, it was confirmed that a sufficient effect was obtained as compared with Comparative Example 2.

  In Example 2, similarly to Example 1, welding was performed with the configuration shown in FIG. With respect to the irradiation angle (φ1) of the laser beam LB, the incident angle of the laser beam LB on the reverse plate-side tapered surface 33t was set to 105 °. The reverse plate side taper surface 33t and the rivet side taper surface 45t are both L = 0.3 mm and H = 0.2 mm (taper angle 34 °).

  As a result, as the welding conditions, welding was realized with an output of 500 W, and the value of the variation in the reverse plate operating pressure (σ) was 0.032 (see FIG. 11). Similar to Example 1, it was confirmed that sufficient effects were obtained.

  In Example 3, similarly to Example 1, welding was performed with the configuration shown in FIG. With respect to the irradiation angle (φ1) of the laser beam LB, the incident angle of the laser beam LB on the reverse plate-side tapered surface 33t was set to 110 °. The reverse plate side taper surface 33t and the rivet side taper surface 45t are both L = 0.3 mm and H = 0.2 mm (taper angle 34 °).

  As a result, as the welding conditions, welding was realized with an output of 600 W, and the value of the reverse plate working pressure variation (σ) was 0.049 (see FIG. 11). Similar to Example 1, it was confirmed that sufficient effects were obtained. The value of the reverse plate working pressure variation (σ) is larger than that of the first embodiment because the output increases because the thickness of the plate to be melted increases as the incident angle with respect to the taper increases. Although it was caused by the above, it was confirmed that it was in a range having no problem.

  In Example 4, similarly to Example 1, welding was performed with the configuration shown in FIG. With respect to the irradiation angle (φ1) of the laser beam LB, the incident angle of the laser beam LB on the reverse plate-side tapered surface 33t was set to 105 °. The reverse plate side taper surface 33t and the rivet side taper surface 45t are both L = 0.3 mm and H = 0.15 mm (taper angle 27 °).

  As a result, as welding conditions, welding was realized with an output of 600 W, and the value of the reverse plate operating pressure variation (σ) was 0.041 (see FIG. 11). Similar to Example 1, it was confirmed that sufficient effects were obtained. Note that the value of the reverse plate working pressure variation (σ) was larger than that in Example 1 because the output increased because the thickness of the plate to be melted was increased by reducing the taper angle. , It was confirmed that there was no problem.

  In Example 5, similarly to Example 1, welding was performed with the configuration shown in FIG. With respect to the irradiation angle (φ1) of the laser beam LB, the incident angle of the laser beam LB on the reverse plate-side tapered surface 33t was set to 105 °. The reverse plate side taper surface 33t and the rivet side taper surface 45t are both L = 0.4 mm and H = 0.2 mm (taper angle 27 °).

  As a result, as the welding conditions, welding was realized with an output of 500 W, and the value of the variation in the reverse plate operating pressure (σ) was 0.035, which was favorable (see FIG. 11). Similar to Example 1, it was confirmed that sufficient effects were obtained. It should be noted that the value of the reverse plate working pressure variation (σ) was smaller than that in Example 1 because the thickness of the taper portion was reduced while being at the same angle as in Example 4, so that welding could be performed at a low output. Thus, it was possible to reduce the variation of the reverse plate operating pressure (σ).

  As mentioned above, although embodiment and the Example based on this invention were described, the content disclosed this time is an illustration and restrictive at no points. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Current interruption device, 10 exterior body, 11 accommodating part, 12 sealing board, 12H through-hole, 13 electrode body (battery element), 14 positive electrode core exposed part, 15 negative electrode core exposed part, 16, 17, 18 gasket, 19 Conductive plate, 20, 24 External terminal, 21, 25 Current collecting terminal, 21L, 21R Flat plate portion, 22 Thick portion, 23 Thin portion, 23H Through hole, 23G Annular groove, 30 Inversion plate (diaphragm), 31 Top surface portion (Reversing part), 32 inclined part, 33 peripheral edge part, 33a outer peripheral end face, 33t reverse plate side taper surface, 40 rivets, 41 crimping part, 42 small diameter part, 43 connecting part, 44 large diameter part, 45 step part, 45a standing wall 45b bottom surface, 45t rivet side taper surface, 60 melting mark, 100 secondary battery.

Claims (4)

A current interrupting device for interrupting a current flow between the battery element and an external terminal provided outside the exterior body when the internal pressure of the exterior body containing the battery element rises;
A circular reversal plate that blocks conduction between the battery element and the external terminal by reversing when the internal pressure of the exterior body rises,
A rivet having an annular step portion that is electrically connected to the external terminal and on which a peripheral portion of the reversing plate is placed;
At the butt portion between the stepped portion and the peripheral edge portion, a fusion mark in which all-around welding was performed while irradiating a laser beam for welding to the entire circumference;
With
In cross-sectional view including the center point of the reversing plate,
The peripheral portion of the reversing plate is provided with a reversing plate-side tapered surface that extends from the outer peripheral end surface of the reversing plate to the bottom surface and approaches the bottom surface of the stepped portion toward the center point side,
The step portion of the rivet is provided with a rivet side taper surface extending substantially parallel to the reversal plate side taper surface from the standing wall facing the outer peripheral end surface of the reversal plate toward the bottom surface of the step portion.
By irradiating the laser beam in a direction intersecting with the reverse plate side taper surface and the rivet side taper surface, the melting marks formed on the reverse plate and the stepped portion become the reverse plate side. A current interrupting device formed to extend from a tapered surface toward the rivet-side tapered surface. The angle at which the reverse plate-side tapered surface of the reverse plate intersects the bottom surface of the reverse plate is more than 90 ° and less than 180 °,
2. The current interrupting device according to claim 1, wherein an incident angle of the laser beam to the reverse plate side tapered surface is 90 ° or more and 110 ° or less.   The current interruption device according to claim 2, wherein an incident angle of the laser beam to the reverse plate side tapered surface is 90 ° or more and 105 ° or less. A battery element;
An exterior body that houses the battery element;
The flow of the electric current between the said battery element and the external terminal provided in the exterior of the said exterior body is interrupted | blocked when the internal pressure of the said exterior body rises, The any one of Claim 1 to 3 Current interrupting device,
A secondary battery comprising:
The exterior body is
A bottomed cylindrical housing portion having an opening and housing the battery element;
A sealing plate for closing the opening,
The current interrupting device is a secondary battery attached to the sealing plate.

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