Secondary battery

Abstract

The present invention provides a secondary battery with high reliability of the connection part between the terminal and the collector. A positive terminal (7) is inserted into a collector through hole (6c) provided in a positive collector (6) and is riveted in a countersunk hole (6d) provided in the positive collector (6). A convex portion (6e) is provided around the collector through hole (6c) on the bottom surface (6d1) of the countersunk hole (6d), a riveted portion (7x) in the positive terminal (7) covers the convex portion (6e), and the riveted portion (7x) in the positive terminal (7) is welded to the edge of the countersunk hole (6d).

Description

Technical Field

[0001] The present disclosure relates to a secondary battery. Background Art

[0002] Alkaline secondary batteries and non-aqueous electrolyte secondary batteries are used as driving power sources for electric vehicles (EV) and hybrid electric vehicles (HEV, PHEV).

[0003] In these secondary batteries, a battery case is formed by a metal outer body having an opening and a sealing plate for sealing the opening. An electrode body consisting of a positive electrode plate, a negative electrode plate and a separator is contained in the battery case together with an electrolyte. A positive terminal and a negative terminal are installed on the sealing plate. The positive terminal is electrically connected to the positive electrode plate via a positive electrode collector, and the negative terminal is electrically connected to the negative electrode plate via a negative electrode collector.

[0004] As a method for connecting the terminal and the current collector, there is a method, for example, in which a through hole is provided in the current collector, one end of the terminal is inserted into the through hole, and the front end of the terminal is riveted to the current collector, thereby connecting the terminal and the current collector. For example, Patent Document 1 discloses that a countersink is provided around the through hole of the current collector, the front end of the terminal is expanded in the countersink, and the expanded portion of the terminal and the edge of the countersink are welded and connected.

[0005] Prior Art Literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-76867

[0008] In a secondary battery in which a terminal is riveted in a countersunk hole of a current collector, a large gap may be formed between the riveted portion of the terminal and the current collector depending on the conditions of the terminal riveting. When such a large gap is formed, there is a concern that the connection between the terminal and the current collector may become unstable.

[0009] exist Fig.15 2 shows an example in which a terminal 507 is inserted into a collector through hole 506c provided in a base portion 506a of the collector, and the terminal 507 is riveted to the base portion 506a. Fig.15As shown, a large gap 90 may be generated between the riveted portion 507x of the terminal 507 and the bottom surface of the countersink 506d provided at the base 506a of the collector. In addition, a large gap 91 may be generated between the riveted portion 507x of the terminal 507 and the side surface of the countersink 506d provided at the base 506a of the collector. Moreover, due to the existence of the gap 90 or the gap 91, there is a concern that the reliability of the connection between the terminal and the collector is reduced. In addition, when the length of the riveted portion 507x of the terminal 507 is extended so that the large gap 91 is not generated between the riveted portion 507x of the terminal 507 and the side surface of the countersink 506d, a large gap 90 becomes easy to be generated between the riveted portion 507x of the terminal 507 and the bottom surface of the countersink 506d. In particular, when the terminal 507 is riveted and fixed to the collector by a single riveting, the gap 90 is easy to be generated. Summary of the invention

[0010] Problems to be solved by the invention

[0011] An object of the present disclosure is to provide a secondary battery in which the reliability of the connection portion between a terminal and a current collector is further improved.

[0012] Means for solving problems

[0013] A secondary battery in one embodiment of the present invention is a secondary battery comprising: an electrode body having a positive electrode plate and a negative electrode plate; an outer body having an opening for accommodating the electrode body; a sealing plate having a terminal mounting hole for sealing the opening; a current collector electrically connected to the positive electrode plate or the negative electrode plate; and a terminal connected to the current collector and inserted into the terminal mounting hole, the current collector having a current collector through-hole, a countersink formed around the current collector through-hole, the countersink having a bottom surface and a side surface, the terminal being inserted into the current collector through-hole and riveted in the countersink, a convex portion being provided on the bottom surface around the current collector through-hole, the riveted portion of the terminal covering the convex portion, and the riveted portion of the terminal being welded to the edge of the countersink.

[0014] According to the structure of a secondary battery in one embodiment of the present disclosure, it is possible to effectively suppress the generation of a large gap between the riveted portion of the terminal and the bottom surface of the countersink, and between the riveted portion of the terminal and the side surface of the countersink. Thus, a secondary battery with a high reliability of the connection portion between the terminal and the collector is achieved. In addition, by riveting the terminal in the countersink, the riveted terminal is deformed to contact both the bottom surface and the side surface of the countersink, making it more difficult to generate a gap between the riveted portion of the terminal and the collector. In addition, by welding the riveted portion of the terminal to the edge of the countersink, the terminal and the collector are more firmly connected.

[0015] A secondary battery in one embodiment of the present invention is a secondary battery comprising: an electrode body having a positive electrode plate and a negative electrode plate; an outer body having an opening for accommodating the electrode body; a sealing plate having a terminal mounting hole for sealing the opening; a current collector electrically connected to the positive electrode plate or the negative electrode plate; and a terminal connected to the current collector and inserted into the terminal mounting hole, the current collector having a current collector through-hole, a countersink formed around the current collector through-hole, the countersink having a bottom surface and a side surface, the terminal being inserted into the current collector through-hole and riveted in the countersink, the bottom surface being inclined so that in the radial direction of the current collector through-hole, the depth of the countersink gradually increases from the current collector through-hole toward the side surface, and the riveted portion of the terminal is welded to the edge of the countersink.

[0016] According to the structure of the secondary battery of one embodiment of the present disclosure, it is possible to effectively suppress the generation of a large gap between the riveted portion of the terminal and the bottom surface of the countersunk hole and between the riveted portion of the terminal and the side surface of the countersunk hole.

[0017] Effects of the Invention

[0018] According to the present disclosure, it is possible to provide a secondary battery in which the reliability of the connection portion between the terminal and the current collector is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram showing the prismatic secondary battery according to the embodiment with the front side wall of the prismatic exterior body and the front portion of the electrode body holder removed.

[0020] Figure 2 It is a top view of a square secondary battery according to an embodiment.

[0021] Figure 3 (a) is a plan view of the positive electrode plate according to the embodiment. Figure 3 (b) is a plan view of the negative electrode plate according to the embodiment.

[0022] Figure 4 It is a perspective view of a positive electrode terminal, an external insulating member, a sealing plate, an internal insulating member, and a positive electrode current collector before assembly.

[0023] Figure 5 This is a diagram showing a surface on the electrode body side of a positive electrode current collector according to an embodiment.

[0024] Figure 6 It is along Figure 5 Cross-sectional view along line VI-VI.

[0025] Figure 7It is a cross-sectional view near the positive terminal along the long side direction of the sealing plate, and is a cross-sectional view after the positive terminal is inserted into the through hole of the external insulating member, the terminal mounting hole of the sealing plate, the through hole of the internal insulating member, and the collector through hole of the positive electrode collector.

[0026] Figure 8 It is a cross-sectional view after the positive electrode terminal is caulked to the positive electrode current collector, and is a cross-sectional view of the vicinity of the positive electrode terminal along the long side direction of the sealing plate.

[0027] Fig. 9 (a) is Figure 8 The enlarged view near IX in FIG. 1 shows the state before laser welding. Fig. 9 (b) is Figure 8 The enlarged view near IX in the figure shows the state after laser welding.

[0028] Fig.10 It is a plan view of the vicinity of the connection portion between the positive electrode terminal and the positive electrode current collector, and is a diagram showing a state after laser welding.

[0029] Fig.11 It is a cross-sectional view of the positive electrode terminal and the positive electrode current collector according to Modification 1, and is a cross-sectional view of the vicinity of the caulked portion of the positive electrode terminal.

[0030] Fig.12 It is a cross-sectional view of the positive electrode terminal and the positive electrode current collector according to Modification 2, and is a cross-sectional view of the vicinity of the caulked portion of the positive electrode terminal.

[0031] Fig.13 It is a cross-sectional view of the positive electrode terminal and the positive electrode current collector according to Modification 3, and is a cross-sectional view of the vicinity of the caulked portion of the positive electrode terminal.

[0032] Fig.14 It is a cross-sectional view of the positive electrode terminal and the positive electrode current collector according to Modification 4, and is a cross-sectional view of the vicinity of the caulked portion of the positive electrode terminal.

[0033] Fig.15 It is a cross-sectional view of a positive electrode terminal and a positive electrode current collector according to a reference example, and is an enlarged cross-sectional view of a caulked portion of the positive electrode terminal.

[0034] Description of Reference Numerals

[0035] 100…Square secondary battery;

[0036] 200…Battery case;

[0037] 1…square outer body;

[0038] 2…sealing plate;

[0039] 2a…Terminal mounting hole;

[0040] 3…electrode body;

[0041] 4… positive plate;

[0042] 4a…positive electrode core;

[0043] 4b…positive electrode active material layer;

[0044] 40 ... a positive electrode core lamination portion;

[0045] 5…negative plate;

[0046] 5a…negative electrode core;

[0047] 5b…negative electrode active material layer;

[0048] 50 ... negative electrode core lamination portion;

[0049] 6…positive electrode current collector;

[0050] 6a…base;

[0051] 6b…lead portion;

[0052] 6c ... collector through hole;

[0053] 6d…countersinking;

[0054] 6d1…bottom;

[0055] 6d2…side;

[0056] 6e...convex part;

[0057] 6f…groove;

[0058] 7…Positive terminal;

[0059] 7a: flange portion;

[0060] 7b…insertion part;

[0061] 7x… riveted parts;

[0062] 8…negative electrode current collector;

[0063] 8a…base;

[0064] 8b…lead portion;

[0065] 9…Negative terminal;

[0066] 9a: flange portion;

[0067] 10…Inner side insulating member;

[0068] 11 ... external insulating member;

[0069] 12…Inner side insulating member;

[0070] 13 ... external insulating member;

[0071] 14…Insulation sheet;

[0072] 15…Gas discharge valve;

[0073] 16…electrolyte injection hole;

[0074] 17 ... sealing member;

[0075] 106a, 206a, 306a, 406a ... base;

[0076] 106c, 206c, 306c, 406c ... current collector through holes;

[0077] 106d, 206d, 306d, 406d… countersinking;

[0078] 106d1, 206d1, 306d1, 406d1...bottom;

[0079] 106d2, 206d2, 306d2, 406d2…side;

[0080] 106e, 206e, 306e...convex part;

[0081] 106f, 206f, 306f, 406f ... groove portion;

[0082] 106x, 206x, 306x, 406x…corners;

[0083] 107, 207, 307, 407… positive terminal;

[0084] 107x, 207x, 307x, 407x… riveted parts. DETAILED DESCRIPTION

[0085] Hereinafter, a prismatic secondary battery as a secondary battery according to an embodiment of the present disclosure will be described with reference to the drawings. The scope of the present disclosure is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical concept of the present invention.

[0086] First, the structure of a rectangular secondary battery 100 according to an embodiment will be described. Figure 1 as well as Figure 2As shown, the square secondary battery 100 has a square outer body 1 with an opening at the top, and a sealing plate 2 for sealing the opening. The battery shell 200 is composed of the square outer body 1 and the sealing plate 2. The square outer body 1 and the sealing plate 2 are respectively made of metal, for example, preferably aluminum or aluminum alloy. In the square outer body 1, a flat wound electrode body 3 formed by winding a strip-shaped positive plate and a strip-shaped negative plate with a strip-shaped separator is contained together with a non-aqueous electrolyte (omitted from the figure). A resin insulating sheet 14 is arranged between the square outer body 1 and the electrode body 3. A gas discharge valve 15 is provided on the sealing plate 2, which ruptures when the pressure in the battery shell 200 becomes above a given value, and the gas in the battery shell 200 is discharged to the outside of the battery shell 200. In addition, the electrolyte injection hole 16 provided in the sealing plate 2 is sealed by a sealing member 17.

[0087] like Figure 3 As shown in (a), the positive electrode plate 4 has a metal positive electrode core 4a and a positive electrode active material layer 4b formed on both sides of the positive electrode core 4a. At the end in the width direction, along the long side direction, the positive electrode plate 4 has a positive electrode core exposed portion where the positive electrode active material layer 4b is not formed on both sides of the positive electrode core 4a. The positive electrode core 4a is preferably made of aluminum or an aluminum alloy. The positive electrode active material layer 4b contains a positive electrode active material. As the positive electrode active material, for example, lithium transition metal composite oxides can be used. In addition, the positive electrode active material layer 4b preferably contains a binder and a conductive material. As the binder, a resin binder is preferably used, for example, polyvinylidene fluoride can be used. As a conductive component, a carbon component such as carbon black is preferred.

[0088] like Figure 3 As shown in (b), the negative electrode plate 5 has a metal negative electrode core 5a and a negative electrode active material layer 5b formed on both sides of the negative electrode core 5a. At the end of the negative electrode plate 5 in the width direction, along the long side direction, there is a negative electrode core exposed portion where the negative electrode active material layer 5b is not formed on both sides of the negative electrode core 5a. The negative electrode core 5a is preferably made of copper or a copper alloy. The negative electrode active material layer 5b contains a negative electrode active material. As the negative electrode active material, for example, carbon materials such as graphite and amorphous carbon, silicon materials such as silicon and silicon oxide, etc. can be used. The negative electrode active material layer 5b preferably contains a binder. As the binder, a resin binder is preferably used, for example, preferably containing styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC). The negative electrode active material layer 5b may also contain a conductive material as needed.

[0089] The wound electrode body 3 has a wound positive electrode core exposed portion at one end and a wound negative electrode core exposed portion at the other end. The wound positive electrode core exposed portion constitutes a positive electrode core laminated portion 40 on which positive electrode cores 4a are laminated. The wound negative electrode core exposed portion constitutes a negative electrode core laminated portion 50 on which negative electrode cores 5a are laminated.

[0090] A positive electrode collector 6 is connected to the positive electrode core laminated portion 40. The positive electrode collector 6 is connected to a positive electrode terminal 7 mounted on the sealing plate 2. An inner side insulating member 10 made of resin is arranged between the sealing plate 2 and the positive electrode collector 6. An outer side insulating member 11 made of resin is arranged between the sealing plate 2 and the positive electrode terminal 7. The positive electrode collector 6 and the positive electrode terminal 7 are electrically insulated from the sealing plate 2 by the inner side insulating member 10 and the outer side insulating member 11. The positive electrode collector 6 and the positive electrode terminal 7 are made of metal, for example, preferably aluminum or an aluminum alloy.

[0091] A negative electrode collector 8 is connected to the negative electrode core laminate 50. The negative electrode collector 8 is connected to a negative terminal 9 mounted on the sealing plate 2. An internal insulating member 12 made of resin is arranged between the sealing plate 2 and the negative electrode collector 8. An external insulating member 13 made of resin is arranged between the sealing plate 2 and the negative terminal 9. The negative electrode collector 8 and the negative terminal 9 are electrically insulated from the sealing plate 2 by the internal insulating member 12 and the external insulating member 13. The negative electrode collector 8 and the negative terminal 9 are made of metal, for example, preferably copper or a copper alloy. In addition, the negative terminal 9 preferably has a portion composed of copper or a copper alloy, and a portion composed of aluminum or an aluminum alloy. Moreover, it is preferred that the portion composed of copper or a copper alloy is connected to the negative electrode collector 8 composed of copper or a copper alloy, and the portion composed of aluminum or an aluminum alloy is exposed on the outer side of the sealing plate 2.

[0092] The positive terminal 7 includes a flange 7a disposed on the battery exterior side relative to the sealing plate 2 and an insertion portion 7b formed on one surface of the flange 7a. The insertion portion 7b penetrates a terminal mounting hole provided in the sealing plate 2 and is connected to the positive current collector 6 .

[0093] The negative terminal 9 includes a flange 9a disposed on the battery exterior side relative to the sealing plate 2 and an insertion portion (not shown) formed on one surface of the flange 9a. The insertion portion passes through a terminal mounting hole (not shown) provided in the sealing plate 2 and is connected to the negative electrode current collector 8.

[0094] The positive electrode current collector 6 includes a base portion 6a disposed between the sealing plate 2 and the electrode body 3 and a lead portion 6b extending from an end of the base portion 6a toward the electrode body 3. The base portion 6a is connected to a positive electrode terminal 7. The lead portion 6b is joined to the positive electrode core laminate portion 40.

[0095] The negative electrode current collector 8 includes a base 8a disposed between the sealing plate 2 and the electrode body 3 and a lead 8b extending from an end of the base 8a toward the electrode body 3. The base 8a is connected to a negative electrode terminal 9. The lead 8b is joined to the negative electrode core laminate 50.

[0096] [Installation to each component of the sealing plate]

[0097] Next, a method for attaching the positive electrode current collector 6 , the positive electrode terminal 7 , the negative electrode current collector 8 , and the negative electrode terminal 9 to the sealing plate 2 will be described.

[0098] Figure 4 It is a perspective view of the positive electrode terminal 7 , the external insulating member 11 , the sealing plate 2 , the internal insulating member 10 , and the base portion 6 a of the positive electrode current collector 6 .

[0099] Around the terminal mounting hole 2a provided in the sealing plate 2, an external insulating member 11 is arranged on the battery exterior side of the sealing plate 2, and an internal insulating member 10 and a base portion 6a of the positive electrode current collector 6 are arranged on the inner surface side of the sealing plate 2. Next, the insertion portion 7b of the positive terminal 7 is inserted from the battery exterior side into the through hole of the external insulating member 11, the terminal mounting hole 2a of the sealing plate 2, the through hole of the internal insulating member 10, and the current collector through hole 6c of the base portion 6a, and the front end side of the insertion portion 7b of the positive terminal 7 is riveted to the base portion 6a. Thus, the positive terminal 7, the external insulating member 11, the sealing plate 2, the internal insulating member 10, and the positive electrode current collector 6 are fixed integrally. In addition, the riveted portion of the front end of the positive terminal 7 may be welded to the base portion 6a.

[0100] Similarly, around the terminal mounting hole (not shown) provided in the sealing plate 2, an external insulating member 13 is arranged on the battery exterior side of the sealing plate 2, and an internal insulating member 12 and a base portion 8a of the negative electrode current collector 8 are arranged on the battery interior side of the sealing plate 2. Next, the negative terminal 9 is inserted from the battery exterior side into the through hole of the external insulating member 13, the terminal mounting hole of the sealing plate 2, the through hole of the internal insulating member 12, and the through hole of the base portion 8a, and the front end side of the negative terminal 9 is riveted to the base portion 8a. Thus, the negative terminal 9, the external insulating member 13, the sealing plate 2, the internal insulating member 12, and the negative electrode current collector 8 are fixed integrally. In addition, the riveted portion of the front end of the negative terminal 9 may be welded to the base portion 8a.

[0101] [Assembly of Prismatic Secondary Battery 100]

[0102] The positive electrode collector 6 mounted on the sealing plate 2 is joined to the positive electrode core laminate 40, and the negative electrode collector 8 mounted on the sealing plate 2 is joined to the negative electrode core laminate 50. Then, the electrode body 3 is covered with the insulating sheet 14, and the electrode body 3 covered by the insulating sheet 14 is inserted into the square outer body 1. Then, the sealing plate 2 is welded to the square outer body 1 by laser welding, and the opening of the square outer body 1 is sealed with the sealing plate 2. After the non-aqueous electrolyte is injected into the battery shell 200 from the electrolyte injection hole 16 of the sealing plate 2, the electrolyte injection hole 16 is sealed with a sealing member 17. Thus, a square secondary battery 100 is formed.

[0103] [Connection between terminal and current collector]

[0104] The detailed structure of the connection portion between the terminal and the current collector will be described using the positive electrode side as an example. The negative electrode side can also be configured in the same manner.

[0105] Figure 5 The figure shows the surface of the base portion 6 a of the positive electrode current collector 6 on the electrode body 3 side. Figure 6 It is along Figure 5 The cross-sectional view of the VI-VI line in FIG. Figure 5 as well as Figure 6 As shown in FIG. 1 , the base portion 6a of the positive electrode current collector 6 has a current collector through hole 6c into which the insertion portion 7b of the positive electrode terminal 7 is inserted. Countersunk holes 6d are provided around the current collector through hole 6c. Fig. 9 As shown in (a), the countersink 6d is a concave portion having a bottom surface 6d1 and a side surface 6d2. Fig. 9 In (a), the upper side is the electrode body 3 side.

[0106] On the bottom surface 6d1 of the countersunk hole 6d, a convex portion 6e is provided along the edge around the collector through hole 6c. Preferably, the convex portion 6e is annular in a plan view. However, it does not necessarily have to be annular. It can also be a convex portion 6e in a shape in which a part of the annular shape is cut off in a plan view. For example, a plurality of convex portions 6e in an arc shape in a plan view can also be formed. Preferably, the convex portion 6e is linear in a plan view. In addition, the surface of the convex portion 6e can be set as a curved surface.

[0107] It is preferable to provide an arc-shaped groove 6f around the countersunk hole 6d. By providing the groove 6f, the shape of the side surface 6d2 of the countersunk hole 6d is stabilized. The countersunk hole 6d and the groove 6f are preferably formed simultaneously by stamping using a mold having concave and convex shapes corresponding to their respective shapes. In this way, it is possible to suppress the metal near the edge of the countersunk hole 6d from flowing to the outer peripheral side, so that the R of the corner formed by the edge of the countersunk hole 6d can be reliably prevented from becoming larger. In addition, the groove 6f is not a necessary structure and may not be provided.

[0108] Figure 7It is a cross-sectional view showing the state after the insertion portion 7b of the positive terminal 7 is inserted into the through hole of the external insulating member 11, the terminal mounting hole 2a of the sealing plate 2, the through hole of the internal insulating member 10, and the collector through hole 6c of the base portion 6a of the positive electrode collector 6. Figure 7 This is a diagram showing a state before the insertion portion 7 b of the positive electrode terminal 7 is caulked. Figure 7 2 is a cross-sectional view of a cross section passing through the center of the current collector through-hole 6c and along the long side direction of the sealing plate 2. Figure 7 In the figure, the upper side is the electrode body 3 side.

[0109] Figure 8 is with Figure 7 2 is a cross-sectional view corresponding to the cross section shown.

[0110] Fig. 9 (a) is Figure 8 The enlarged view near IX in FIG. 1 is a view showing a state before the caulked portion 7 x of the positive electrode terminal 7 and the base portion 6 a of the positive electrode current collector 6 are laser welded.

[0111] Fig. 9 (b) is Figure 8 The enlarged view near IX in FIG. 1 is a view showing a state after the caulked portion 7 x of the positive electrode terminal 7 and the base portion 6 a of the positive electrode current collector 6 are laser welded.

[0112] By providing the convex portion 6e on the bottom surface 6d1 of the countersunk hole 6d of the base portion 6a, it is possible to effectively suppress the generation of a large gap between the riveted portion 7x of the positive terminal 7 and the base portion 6a. Therefore, the positive terminal 7 and the base portion 6a are more firmly connected. In addition, the riveted portion 7x of the positive terminal 7 and the edge of the countersunk hole 6d of the base portion 6a can be stably welded and connected. Therefore, the reliability of the connection portion between the positive terminal 7 and the base portion 6a is high.

[0113] Fig.10 1 is a diagram showing a state after laser welding of the caulked portion 7 x of the positive electrode terminal 7 and the base portion 6 a of the positive electrode current collector 6 , and is a plan view of the caulked portion 7 x of the positive electrode terminal 7 and the base portion 6 a of the positive electrode current collector 6 .

[0114] like Fig.10 As shown, the edge of the countersunk hole 6d provided at the base 6a of the positive electrode current collector 6 and the riveted portion 7x of the positive terminal 7 are welded and connected to form a welded portion 60. In addition, the welded portion 60 can be formed in a plurality of points or in a line. In addition, the welded portion 60 can also be formed in a ring shape. It is preferred to provide a convex portion 6e on a straight line connecting the center of the collector through hole 6c and the welded portion 60 in a plan view.

[0115] [Modification 1]

[0116] Fig.11 This is an enlarged cross-sectional view of the vicinity of the connection portion between the positive electrode terminal 107 and the base portion 106 a of the positive electrode current collector in the prismatic secondary battery according to Modification 1. Fig.11 is with Fig. 9 (a) corresponds to the cross-sectional view. Fig.11 The state before laser welding of the riveted portion 107x of the positive electrode terminal 107 and the base portion 106a of the positive electrode current collector is shown. In Modification 1, the shape of the countersunk hole 106d provided in the base portion 106a of the positive electrode current collector is different from that in the above-mentioned embodiment.

[0117] A current collector through hole 106c is provided at the base portion 106a of the positive electrode current collector. A countersink 106d is formed around the current collector through hole 106c. The countersink 106d has a bottom surface 106d1 and a side surface 106d2. On the bottom surface 106d1, a convex portion 106e is provided around the current collector through hole 106c. A groove portion 106f is provided around the countersink 106d.

[0118] The positive terminal 107 is inserted into the collector through hole 106c, and the front end is riveted in the countersunk hole 106d. The riveted portion 107x of the positive terminal 107 covers the convex portion 106e and contacts the bottom surface 106d1 and the side surface 106d2. Since the convex portion 106e is provided, a large gap is not easily generated between the riveted portion 107x of the positive terminal 107 and the base portion 106a.

[0119] In the positive electrode collector of modification example 1, a corner portion 106x is formed at the edge of the collector through hole 106c. The R of the corner portion 106x is preferably 0.05 mm or less. As a result, the positive terminal 107 is more firmly crimped to the base 106a of the positive electrode collector. Therefore, the positive terminal 107 and the base 106a of the positive electrode collector are more firmly connected. In addition, it is preferred to weld and connect the riveted portion 107x of the positive terminal 107 and the edge of the countersunk hole 106d by laser or the like.

[0120] The inner side surface of the current collector through hole 106c becomes one side surface of the convex portion 106e. Fig.11 The convex portion 106e is arranged at a position separated from the side surface 106d2.

[0121] [Modification 2]

[0122] Fig.12This is an enlarged cross-sectional view of the vicinity of the connection portion between the positive electrode terminal 207 and the base portion 206 a of the positive electrode current collector in the prismatic secondary battery according to Modification 2. Fig.12 is with Fig. 9 (a) corresponds to the cross-sectional view. Fig.12 The state before laser welding of the riveted portion 207x of the positive electrode terminal 207 and the base portion 206a of the positive electrode current collector is shown. In Modification 2, the shape of the countersunk hole 206d provided in the base portion 206a of the positive electrode current collector is different from that in the above-mentioned embodiment.

[0123] A collector through hole 206c is provided at the base 206a of the positive electrode current collector. A countersink 206d is formed around the collector through hole 206c. The countersink 206d has a bottom surface 206d1 and a side surface 206d2. On the bottom surface 206d1, a convex portion 206e is provided around the collector through hole 206c. The convex portion 206e has a curved surface portion. The convex portion 206e is arranged at a position separated from the side surface 206d2. A groove portion 206f is provided around the countersink 206d.

[0124] The positive terminal 207 is inserted into the collector through hole 206c, and the front end is riveted in the countersunk hole 206d. The riveted portion 207x of the positive terminal 207 covers the convex portion 206e and contacts the bottom surface 206d1 and the side surface 206d2. Since the convex portion 206e is provided, a large gap is not easily generated between the riveted portion 207x of the positive terminal 207 and the base portion 206a.

[0125] In the positive electrode collector of variant example 2, the protrusion 206e is formed at a position separated from the edge of the collector through hole 206c. In addition, a corner 206x is formed at the edge of the collector through hole 206c. The R of the corner 206x is preferably less than 0.05mm. As a result, the positive terminal 207 is more firmly crimped to the base 206a of the positive electrode collector. Therefore, the positive terminal 207 and the base 206a of the positive electrode collector are more firmly connected. In addition, it is preferred to weld and connect the riveted portion 207x of the positive terminal 207 and the edge of the countersunk hole 206d by laser or the like.

[0126] [Variation 3]

[0127] Fig.13 This is an enlarged cross-sectional view of the vicinity of the connection portion between the positive electrode terminal 307 and the base portion 306 a of the positive electrode current collector in the prismatic secondary battery according to Modification 3. Fig.13 is with Fig. 9 (a) corresponds to the cross-sectional view. Fig.13The state before laser welding of the riveted portion 307x of the positive electrode terminal 307 and the base portion 306a of the positive electrode current collector is shown. In Modification 3, the shape of the countersunk hole 306d provided in the base portion 306a of the positive electrode current collector is different from that in the above-mentioned embodiment.

[0128] The base 306a of the positive electrode current collector is provided with a current collector through hole 306c. A countersunk hole 306d is formed around the current collector through hole 306c. The countersunk hole 306d has a bottom surface 306d1 and a side surface 306d2. On the bottom surface 306d1, a convex portion 306e is provided around the current collector through hole 306c. The convex portion 306e is formed at the front end (at the Fig.13 The convex portion 306e is arranged at a position separated from the side surface 306d2. A groove portion 306f is provided around the countersunk hole 306d.

[0129] The positive terminal 307 is inserted into the collector through hole 306c, and the front end is riveted in the countersunk hole 306d. The riveted portion 307x of the positive terminal 307 covers the convex portion 306e and contacts the bottom surface 306d1 and the side surface 306d2. Since the convex portion 306e is provided, a large gap is not easily generated between the riveted portion 307x of the positive terminal 307 and the base portion 306a.

[0130] In the positive electrode collector of variant example 3, the convex portion 306e is formed at a position separated from the edge of the collector through hole 306c. In addition, a corner portion 306x is formed at the edge of the collector through hole 306c. The R of the corner portion 306x is preferably less than 0.05mm. As a result, the positive terminal 307 is more firmly crimped to the base 306a of the positive electrode collector. Thus, the positive terminal 307 and the base 306a of the positive electrode collector are more firmly connected. In addition, it is preferred to weld and connect the riveted portion 307x of the positive terminal 307 and the edge of the countersunk hole 306d by laser or the like.

[0131] [Variation 4]

[0132] Fig.14 This is an enlarged cross-sectional view of the vicinity of the connection portion between the positive electrode terminal 407 and the base portion 406 a of the positive electrode current collector in the prismatic secondary battery according to Modification 4. Fig.14 is with Fig. 9 (a) corresponds to the cross-sectional view. Fig.14 The state before laser welding of the riveted portion 407x of the positive electrode terminal 407 and the base portion 406a of the positive electrode current collector is shown. In Modification 4, the shape of the countersunk hole 406d provided in the base portion 406a of the positive electrode current collector is different from that in the above-mentioned embodiment.

[0133] The current collector through hole 406c is provided in the base portion 406a of the positive electrode current collector. A countersink 406d is formed around the current collector through hole 406c. The countersink 406d has a bottom surface 406d1 and a side surface 406d2. A groove portion 406f is provided around the countersink 406d.

[0134] The positive terminal 407 is inserted into the collector through hole 406c, and the front end is riveted in the countersunk hole 406d. The riveted portion 407x of the positive terminal 407 contacts the bottom surface 406d1 and the side surface 406d2. The bottom surface 406d1 is inclined so that the positive terminal 407 is in the radial direction of the collector through hole 406c (in Fig.14 In the left-right direction, the depth of the countersunk hole 406d gradually increases from the collector through hole 406c toward the side surface 406d2. Therefore, a large gap is not easily generated between the riveted portion 407x of the positive terminal 407 and the base portion 406a.

[0135] like Fig.14 As shown, the angle formed by the collector through hole 406c and the bottom surface 406d1 is preferably less than 90°. As a result, the positive terminal 407 is more firmly pressed against the base 406a of the positive electrode collector. Therefore, the positive terminal 407 and the base 406a of the positive electrode collector are more firmly connected.

[0136] In the positive electrode collector of modification example 4, a corner portion 406x is formed at the edge of the collector through hole 406c. The R of the corner portion 406x is preferably 0.05 mm or less. As a result, the positive terminal 407 is more firmly crimped to the base 406a of the positive electrode collector. Thus, the positive terminal 407 and the base 406a of the positive electrode collector are more firmly connected. In addition, it is preferred to weld and connect the riveted portion 407x of the positive terminal 407 and the edge of the countersunk hole 406d by laser or the like.

[0137] [other]

[0138] The top view shape of the collector through hole is preferably an ellipse or a racetrack shape. In addition, the cross-sectional shape of the insertion portion of the terminal in a direction parallel to the sealing plate is preferably set to the same shape as the top view shape of the collector through hole. Thus, the terminal can be prevented from rotating relative to the sealing plate. In addition, the top view shape of the collector through hole can also be a perfect circle.

[0139] The top view shape of the countersink is preferably an ellipse or a racetrack. With such a structure, the insertion portion of the terminal is riveted in the countersink, thereby more reliably preventing the terminal from rotating relative to the collector. In addition, the top view shape of the countersink may also be a perfect circle.

[0140] The depth of the countersink is not limited, but is, for example, preferably 0.2 to 1.0 mm, more preferably 0.2 to 0.5 mm, and further preferably 0.2 to 0.4 mm.

[0141] The width of the countersunk hole in the radial direction of the current collector through-hole (the distance from the edge of the current collector through-hole to the side surface of the countersunk hole) is preferably 0.5 to 3.0 mm, more preferably 0.5 to 2.0 mm, and even more preferably 0.5 to 1.3 mm.

[0142] The width of the projection in the radial direction of the current collector through-hole is preferably 0.3 to 2.0 mm, more preferably 0.5 to 1.5 mm, and even more preferably 0.6 to 1.0 mm.

[0143] The height of the convex portion is preferably smaller than the depth of the countersink. The height of the convex portion is more preferably 0.1 to 0.5 times the depth of the countersink.

[0144] The present invention is particularly effective when the terminal is fixed to the current collector by caulking at one time.

Claims

1. A secondary battery comprising: An electrode body having a positive electrode plate and a negative electrode plate; An outer body having an opening and accommodating the electrode body; A sealing plate having a terminal mounting hole for sealing the opening; a current collector disposed in the outer casing and electrically connected to the positive electrode plate or the negative electrode plate; and A terminal connected to the current collector and inserted into the terminal mounting hole, The current collector has a current collector through-hole, a countersink is formed on a surface around the current collector through-hole facing the electrode body, and the countersink has a bottom surface and side surfaces. The terminal is inserted into the collector through-hole and riveted in the countersunk hole. A convex portion is provided around the collector through hole in the bottom surface, and the riveted portion of the terminal covers the convex portion. The riveted portion of the terminal is welded to the side of the countersunk hole, In the thickness direction of the sealing plate, the height of the protrusion from the bottom surface is smaller than the depth of the side surface of the countersunk hole to the bottom surface. The surface of the riveted portion of the terminal facing the electrode body is inclined in a direction perpendicular to the thickness direction of the sealing plate so as to be away from the electrode body as it moves away from the collector through-hole. An outer end portion of the caulked portion of the terminal abuts against the side surface in a direction perpendicular to the thickness direction of the sealing plate.

2. The secondary battery according to claim 1, wherein A curved surface portion is formed on a surface of the convex portion.

3. The secondary battery according to claim 1 or 2, wherein: The front end of the riveted portion of the terminal is in contact with the side surface.

4. The secondary battery according to claim 1 or 2, wherein: The height of the convex portion is 0.1 to 0.5 times the depth of the countersink.

5. The secondary battery according to claim 1 or 2, wherein: The R of the corner portion of the edge of the current collector through-hole is 0.05 mm or less.

6. A secondary battery comprising: An electrode body having a positive electrode plate and a negative electrode plate; An outer body having an opening and accommodating the electrode body; A sealing plate having a terminal mounting hole for sealing the opening; a current collector disposed in the outer casing and electrically connected to the positive electrode plate or the negative electrode plate; and A terminal connected to the current collector and inserted into the terminal mounting hole, The current collector has a current collector through hole, and a countersunk hole is formed on a surface of the current collector through hole facing the electrode body. The countersink has a bottom surface and a side surface, The terminal is inserted into the collector through-hole and riveted in the countersunk hole. The bottom surface is inclined so that in the radial direction of the current collector through hole, the depth of the countersunk hole gradually increases from the current collector through hole toward the side surface. The riveted portion of the terminal is welded to the side of the countersunk hole, In the thickness direction of the sealing plate, the height of the inclined portion from the bottom surface is smaller than the depth of the side surface of the countersunk hole to the bottom surface. The surface of the riveted portion of the terminal facing the electrode body is inclined in a direction perpendicular to the thickness direction of the sealing plate so as to be away from the electrode body as it moves away from the collector through-hole. An outer end portion of the caulked portion of the terminal abuts against the side surface in a direction perpendicular to the thickness direction of the sealing plate.

7. The secondary battery according to claim 6, wherein The front end of the riveted portion of the terminal is in contact with the side surface.

8. The secondary battery according to claim 6 or 7, wherein: The R of the corner portion of the edge of the current collector through-hole is 0.05 mm or less.

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