Prismatic secondary battery

Abstract

A highly reliable prismatic secondary battery with a high volumetric energy density is provided. [Solution] In the prismatic secondary battery of the present invention, the electrode body includes first and second electrode body elements each including a positive electrode plate and a negative electrode plate, and the first and second electrode body elements are each aligned in the short-side direction of the sealing plate, a first tab group of one of the positive and negative electrode plates in the first electrode body element and a second tab group of one of the positive and negative electrode plates in the second electrode body element are electrically connected to a current collecting member, and in the current collecting member, a connection portion with the first tab group and a connection portion with the second tab group are aligned in the short-side direction of the sealing plate, and an electrolyte injection hole is arranged between the connection portion with the first tab group and the connection portion with the second tab group in the short-side direction of the sealing plate.

Description

[Technical field]

[0001] The present invention relates to a prismatic secondary battery. [Background technology]

[0002] 2. Description of the Related Art Prismatic secondary batteries, such as nonaqueous electrolyte secondary batteries, are used as driving power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs, PHEVs), and the like.

[0003] In these prismatic secondary batteries, a battery case is formed by a cylindrical prismatic exterior body with a bottom and an opening, and a sealing plate that seals the opening. An electrode assembly consisting of a positive electrode plate, a negative electrode plate, and a separator is housed in the battery case together with an electrolyte. A positive electrode terminal and a negative electrode terminal are attached to the sealing plate. The positive electrode terminal is electrically connected to the positive electrode plate via a positive electrode current collector, and the negative electrode terminal is electrically connected to the negative electrode plate via a negative electrode current collector.

[0004] The positive electrode plate includes a metallic positive electrode core and a positive electrode active material mixture layer formed on the positive electrode core surface. A positive electrode core exposed portion where the positive electrode active material mixture layer is not formed is formed in a part of the positive electrode core. A positive electrode current collector is connected to this positive electrode core exposed portion. The negative electrode plate includes a metallic negative electrode core and a negative electrode active material mixture layer formed on the negative electrode core surface. A negative electrode core exposed portion where the negative electrode active material mixture layer is not formed is formed in a part of the negative electrode core. A negative electrode current collector is connected to this negative electrode core exposed portion.

[0005] For example, Patent Document 1 proposes a prismatic secondary battery using a wound electrode assembly having a wound positive electrode core exposed portion at one end and a wound negative electrode core exposed portion at the other end. Patent Document 2 proposes a prismatic secondary battery using an electrode assembly having a positive electrode core exposed portion and a negative electrode core exposed portion provided at one end. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2009-032640 A [Patent Document 2] JP 2008-226625 A Summary of the Invention [Problem to be solved by the invention]

[0007] Regarding secondary batteries for vehicles, particularly prismatic secondary batteries used in EVs, PHEVs, and the like, there is a demand for the development of prismatic secondary batteries with higher volumetric energy density and larger battery capacity. In the case of the prismatic secondary battery disclosed in the above Patent Document 1, the battery case requires left and right spaces for arranging the wound positive electrode core exposed portion and the wound negative electrode core exposed portion, and an upper space between the sealing plate and the wound electrode body, which makes it difficult to increase the volumetric energy density of the prismatic secondary battery. In contrast, as in the prismatic secondary battery disclosed in the above Patent Document 2, by arranging the positive electrode core exposed portion and the negative electrode core exposed portion on the sealing plate side, a prismatic secondary battery with high volumetric energy density can be easily obtained.

[0008] A main object of the present invention is to provide a prismatic secondary battery having improved volumetric energy density and higher reliability. [Means for solving the problem]

[0009] A prismatic secondary battery according to one embodiment of the present invention comprises an electrode body including a positive electrode plate and a negative electrode plate, a prismatic exterior body having an opening and housing the electrode body, a sealing plate sealing the opening and having a longitudinal direction and a transverse direction, an electrolyte injection hole provided in the sealing plate, a tab provided on the positive electrode plate or the negative electrode plate, a tab group consisting of a plurality of tabs, a terminal electrically connected to the tab group and attached to the sealing plate, a current collecting member electrically connected to the tab group and the terminal, and an insulating member disposed between the sealing plate and the current collecting member, and the electrode body comprises a first electrode body element including the positive electrode plate and the negative electrode plate, and a second electrode body element including the positive electrode plate and the negative electrode plate. and a second electrode body element including an electrode plate, the first electrode plate element and the second electrode body element being aligned in a short-side direction of a sealing plate, a first tab group of one of the positive and negative electrode plates in the first electrode body element and a second tab group of one of the positive and negative electrode plates in the second electrode body element being electrically connected to a current collecting member, in the current collecting member, a connection portion with the first tab group and a connection portion with the second tab group being aligned in the short-side direction of the sealing plate, and an electrolyte injection hole being disposed between the connection portion with the first tab group and the connection portion with the second tab group in the short-side direction of the sealing plate. Effect of the Invention

[0010] According to the present invention, a prismatic secondary battery having a higher volumetric energy density and high reliability can be provided. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view of a prismatic secondary battery according to an embodiment; [Diagram 2] 2 is a cross-sectional view of the prismatic secondary battery taken along line II-II in FIG. 1. [Diagram 3] FIG. 2 is a plan view of a positive electrode plate according to the embodiment. [Figure 4] FIG. 2 is a plan view of a negative electrode plate according to the embodiment. [Diagram 5] FIG. 2 is a plan view of an electrode body element according to an embodiment. [Figure 6] 2 is a perspective view of a positive electrode terminal, an outer insulating member, a sealing plate, a first insulating member, and a conductive member. FIG. [Figure 7]FIG. 4 is a bottom view of the sealing plate after each component is attached. [Figure 8] 8A is a cross-sectional view taken along line VIIIA-VIIIA in FIG. 7, FIG. 8B is a cross-sectional view taken along line VIIIB-VIIIB in FIG. 7, and FIG. 8C is a cross-sectional view taken along line VIIIC-VIIIC in FIG. [Figure 9] FIG. [Figure 10] FIG. 10A is a perspective view of the first positive current collector and the second insulating member before assembly, FIG. 10B is a perspective view of the first positive current collector and the second insulating member after assembly, and FIG. 10C is a perspective view of the first positive current collector and the second insulating member after fixing. [Figure 11] 8B is an enlarged view of the vicinity of the connection portion between the deformation plate and the first positive electrode current collector in FIG. 8A. FIG. [Figure 12] FIG. 2 is a perspective view of a sealing plate with components attached thereto. [Figure 13] FIG. 4 is a cross-sectional view taken along the longitudinal direction of the sealing plate in the vicinity of the negative electrode terminal. [Figure 14] 11A to 11C are diagrams showing a method of attaching a tab to a current collecting member. [Figure 15] FIG. 13 is a diagram showing a step of disposing a second positive electrode current collector on a sealing plate via a second insulating member. [Figure 16] 1. FIG. 2 is a cross-sectional view of the sealing plate and its vicinity taken along the line XVI-XVI in FIG. [Figure 17] FIG. 4 is a diagram showing the inner surface of the sealing plate of the battery before each component is attached. [Figure 18] FIG. 4 is a perspective view of an internal insulating member on the negative electrode side. [Figure 19] 1. FIG. 4 is a cross-sectional view of the vicinity of the sealing plate of a prismatic secondary battery according to a modified example taken along the line XVI-XVI in FIG. [Figure 20] 20 is an enlarged view of the vicinity of the first positive electrode tab group in FIG. 19. [Figure 21] 20 is an enlarged view of the vicinity of the second positive electrode tab group in FIG. 19. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The configuration of the prismatic secondary battery 20 according to the embodiment will be described below. Note that the present invention is not limited to the following embodiment.

[0013] FIG. 1 is a perspective view of a prismatic secondary battery 20. FIG. 2 is a cross-sectional view of the II-II section of FIG. 1. As shown in FIGS. 1 and 2, the prismatic secondary battery 20 includes a battery case 100 including a prismatic exterior body 1 in the form of a bottomed rectangular cylinder having an opening, and a sealing plate 2 that seals the opening of the prismatic exterior body 1. The prismatic exterior body 1 and the sealing plate 2 are each preferably made of metal, for example, aluminum or an aluminum alloy. A laminated electrode body 3 in which a positive electrode plate and a negative electrode plate are laminated with a separator interposed therebetween is accommodated in the prismatic exterior body 1 together with an electrolyte. A resin insulating sheet 14 is disposed between the electrode body 3 and the prismatic exterior body 1.

[0014] A positive electrode tab 40 and a negative electrode tab 50 are provided at the end of the electrode body 3 on the sealing plate 2 side. The positive electrode tab 40 is electrically connected to the positive electrode terminal 7 via the second positive electrode current collector 6b and the first positive electrode current collector 6a. The negative electrode tab 50 is electrically connected to the negative electrode terminal 9 via the second negative electrode current collector 8b and the first negative electrode current collector 8a. Here, the first positive electrode current collector 6a and the second positive electrode current collector 6b constitute the positive electrode current collector 6. Also, the first negative electrode current collector 8a and the second negative electrode current collector 8b constitute the negative electrode current collector 8. Note that the positive electrode current collector 6 can be formed as one component. Also, the negative electrode current collector 8 can be formed as one component.

[0015] The positive electrode terminal 7 is fixed to the sealing plate 2 via a resin external insulating member 11. The negative electrode terminal 9 is fixed to the sealing plate 2 via a resin external insulating member 13. The positive electrode terminal 7 is preferably made of a metal, more preferably made of aluminum or an aluminum alloy. The negative electrode terminal 9 is preferably made of a metal, more preferably made of copper or a copper alloy.

[0016] It is preferable that the conductive path between the positive electrode plate and the positive electrode terminal 7 is provided with a current interruption mechanism 60 that operates when the pressure inside the battery case 100 reaches or exceeds a predetermined value, and interrupts the conductive path between the positive electrode plate and the positive electrode terminal 7. A current interruption mechanism may be provided in the conductive path between the negative electrode plate and the negative electrode terminal 9.

[0017] The sealing plate 2 is provided with a gas exhaust valve 17 that breaks when the pressure inside the battery case 100 reaches or exceeds a predetermined value, and exhausts gas inside the battery case 100 to the outside of the battery case 100. The operating pressure of the gas exhaust valve 17 is set to a value higher than the operating pressure of the current interruption mechanism 60.

[0018] The sealing plate 2 is provided with an electrolyte injection hole 15. After the electrolyte is injected into the battery case 100 through the electrolyte injection hole 15, the electrolyte injection hole 15 is sealed with a sealing plug 16. As the sealing plug 16, a blind rivet is preferably used.

[0019] Next, a method for manufacturing the prismatic secondary battery 20 and each of its components will be described in detail. [Preparation of positive electrode plate] A positive electrode slurry containing lithium nickel cobalt manganese composite oxide as a positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, a carbon material as a conductive agent, and N-methyl-2-pyrrolidone (NMP) as a dispersion medium is prepared. This positive electrode slurry is applied to both sides of a rectangular aluminum foil having a thickness of 15 μm as a positive electrode core. Then, by drying, the NMP in the positive electrode slurry is removed, and a positive electrode active material mixture layer is formed on the positive electrode core. Then, a compression process is performed so that the positive electrode active material mixture layer has a predetermined thickness. The positive electrode plate thus obtained is cut into a predetermined shape.

[0020] FIG. 3 is a plan view of the positive electrode plate 4 produced by the above-mentioned method. As shown in FIG. 3, the positive electrode plate 4 has a main body in which a positive electrode active material mixture layer 4b is formed on both sides of a rectangular positive electrode core 4a. The positive electrode core 4a protrudes from the end side of the main body, and this protruding positive electrode core 4a constitutes a positive electrode tab 40. The positive electrode tab 40 may be a part of the positive electrode core 4a as shown in FIG. 3, or another member may be connected to the positive electrode core 4a to form the positive electrode tab 40. In addition, a positive electrode protective layer 4d having an electrical resistance larger than the electrical resistance of the positive electrode active material mixture layer 4b is preferably provided in a portion of the positive electrode tab 40 adjacent to the positive electrode active material mixture layer 4b. [Preparation of negative electrode plate] A negative electrode slurry containing graphite as a negative electrode active material, styrene butadiene rubber (SBR) as a binder, carboxymethyl cellulose (CMC) as a thickener, and water is prepared. This negative electrode slurry is applied to both sides of a rectangular copper foil having a thickness of 8 μm as a negative electrode core. Then, the negative electrode slurry is dried to remove the water in the negative electrode slurry, and a negative electrode active material mixture layer is formed on the negative core. Then, a compression process is performed so that the negative electrode active material mixture layer has a predetermined thickness. The negative electrode plate thus obtained is cut into a predetermined shape.

[0021] Fig. 4 is a plan view of the negative electrode plate 5 produced by the above-mentioned method. As shown in Fig. 4, the negative electrode plate 5 has a main body in which a negative electrode active material mixture layer 5b is formed on both sides of a rectangular negative electrode core 5a. The negative electrode core 5a protrudes from an end side of the main body, and this protruding negative electrode core 5a constitutes a negative electrode tab 50. The negative electrode tab 50 may be a part of the negative electrode core 5a as shown in Fig. 4, or another member may be connected to the negative electrode core 5a to form the negative electrode tab 50. [Fabrication of electrode elements] Fifty positive electrode plates 4 and fifty-one negative electrode plates 5 are prepared by the above-mentioned method, and these are stacked with a rectangular separator made of polyolefin interposed therebetween to prepare a laminated electrode body element (3a, 3b). As shown in FIG. 5, the laminated electrode body element (3a, 3b) is prepared so that the positive electrode tabs 40 of each positive electrode plate 4 are stacked at one end, and the negative electrode tabs 50 of each negative electrode plate 5 are stacked at the other end. Separators are arranged on both outer surfaces of the electrode body element (3a, 3b), and each electrode plate and separator can be fixed in a stacked state with tape or the like. Alternatively, an adhesive layer may be provided on the separator, and the separator and the positive electrode plate 4 and the separator and the negative electrode plate 5 may be respectively adhered to each other.

[0022] The size of the separator in a plan view is preferably the same as or larger than the negative electrode plate 5. The positive electrode plate 4 may be disposed between two separators, and the edges of the separators may be heat-welded, after which the positive electrode plate 4 and the negative electrode plate 5 may be laminated. When producing the electrode body elements (3a, 3b), a long separator may be used, and the positive electrode plate 4 and the negative electrode plate 5 may be laminated while folding the long separator zigzag. Alternatively, a long separator may be used, and the positive electrode plate 4 and the negative electrode plate 5 may be laminated while winding the long separator.

[0023] [Installing each part on the sealing plate (positive electrode side)] 2, 6 to 8, a method of attaching the positive electrode terminal 7 and the first positive electrode current collector 6a to the sealing plate 2, and a configuration in the vicinity of the positive electrode terminal 7 will be described. FIG. 6 is a perspective view of the positive electrode terminal 7, the outer insulating member 11, the sealing plate 2, the first insulating member 10, and the conductive member 61 before assembly. FIG. 7 is a view showing the inner surface side of the sealing plate 2 after each part is attached. In FIG. 7, the positive electrode tab 40 and the negative electrode tab 50 are not shown. FIG. 8A is a cross-sectional view of the vicinity of the positive electrode terminal 7 along the line VIIIA-VIIIA in FIG. 7. FIG. 8B is a cross-sectional view of the vicinity of the positive electrode terminal 7 along the line VIIIB-VIIIB in FIG. 7. FIG. 8C is a cross-sectional view of the vicinity of the positive electrode terminal 7 along the line VIIIC-VIIIC in FIG. 7.

[0024] In the sealing plate 2, the external insulating member 11 is disposed on the battery outer surface side near the positive terminal mounting hole 2a, and the first insulating member 10 and the conductive member 61 are disposed on the battery inner surface side near the positive terminal mounting hole 2a. Next, the insertion portion 7b provided on one side of the flange portion 7a in the positive terminal 7 is inserted into the first terminal insertion hole 11a of the external insulating member 11, the positive terminal mounting hole 2a of the sealing plate 2, the second terminal insertion hole 10d of the first insulating member 10, and the third terminal insertion hole 61c of the conductive member 61. Then, the tip of the insertion portion 7b is crimped onto the conductive member 61. As a result, the positive terminal 7, the external insulating member 11, the sealing plate 2, the first insulating member 10, and the conductive member 61 are fixed. Note that, by crimping the insertion portion 7b of the positive terminal 7, an expanded diameter portion having an outer diameter larger than the inner diameter of the third terminal insertion hole 61c of the conductive member 61 is formed on the tip side of the insertion portion 7b. The crimped portion of the insertion portion 7b of the positive terminal 7 and the conductive member 61 are preferably welded by laser welding, etc. Furthermore, the first insulating member 10 and the outer insulating member 11 are preferably made of resin.

[0025] As shown in FIG. 6 and FIG. 8, the first insulating member 10 has a first insulating member body 10a disposed so as to face the sealing plate 2. A pair of first side walls 10b is provided at both ends of the first insulating member body 10a in the longitudinal direction of the sealing plate 2. A pair of second side walls 10c is provided at both ends of the first insulating member body 10a in the lateral direction of the sealing plate 2. A second terminal insertion hole 10d is provided in the first insulating member body 10a. A first connecting portion 10e is provided on the outer surface side of the second side wall 10c. The first connecting portion 10e is preferably provided in the center of the second side wall 10c in the longitudinal direction of the sealing plate 2. In addition, a second connecting portion 10f is provided on the outer surface side of the second side wall 10c. The second connecting portion 10f is preferably provided at the end of the second side wall 10c in the longitudinal direction of the sealing plate 2. A first groove 10x is provided on the surface of the first insulating member main body 10a facing the sealing plate 2, and a second groove 10y is provided on the surface of the first insulating member main body 10a facing the conductive member 61. The second groove 10y is located on the outer periphery side of the first groove 10x. A recess 10g is provided in a corner of the surface of the first insulating member main body 10a facing the sealing plate 2.

[0026] As shown in FIG. 6 and FIG. 8, the conductive member 61 has a conductive member base portion 61a arranged to face the first insulating member main body portion 10a, and a tubular portion 61b extending from the edge of the conductive member base portion 61a toward the electrode body 3. The cross-sectional shape of the tubular portion 61b parallel to the sealing plate 2 may be circular or rectangular. A flange portion 61d is provided at the end of the tubular portion 61b on the electrode body 3 side. A conductive member opening portion 61f is provided at the end of the tubular portion 61b on the electrode body 3 side. A pressing protrusion 61e is provided on the surface of the conductive member base portion 61a facing the first insulating member 10. The pressing protrusion 61e presses the first insulating member 10 toward the sealing plate 2. The pressing protrusion 61e is preferably formed on the edge of the third terminal insertion hole 61c or in the vicinity thereof.

[0027] Next, the deforming plate 62 is arranged so as to close the conductive member opening 61f of the conductive member 61, and the periphery of the deforming plate 62 is welded to the conductive member 61 by laser welding or the like. As a result, the conductive member opening 61f of the conductive member 61 is sealed by the deforming plate 62. Note that the conductive member 61 and the deforming plate 62 are each preferably made of a metal, and more preferably made of aluminum or an aluminum alloy.

[0028] FIG. 9 is a perspective view of the deformation plate 62. In FIG. 9, the upper side is the electrode body 3 side, and the lower side is the sealing plate 2 side. As shown in FIG. 9, the deformation plate 62 has a stepped protrusion 62a protruding toward the electrode body 3 side at the center. The stepped protrusion 62a includes a first protrusion 62a1 and a second protrusion 62a2 having a smaller outer diameter than the first protrusion 62a1 and protruding from the first protrusion 62a1 toward the electrode body 3 side. The deformation plate 62 has an annular rib 62b protruding toward the electrode body 3 side at the outer periphery. The surface of the deformation plate 62 on the electrode body 3 side is provided with an annular thin portion 62c. The deformation plate 62 may have any shape as long as it can seal the conductive member opening 61f of the conductive member 61.

[0029] Next, a method for fixing the second insulating member 63 and the first positive electrode current collector 6a will be described with reference to Fig. 10. In Fig. 10, the surface of the prismatic secondary battery 20 that faces the electrode body 3 is located on the upper side, and the surface that faces the sealing plate 2 is located on the lower side.

[0030] As shown in FIG. 10A, the first positive electrode collector 6a has a connection hole 6c. The edge of the connection hole 6c is welded to the deformable plate 62. In the first positive electrode collector 6a, four fixing holes 6d are provided around the connection hole 6c. The number of fixing holes 6d may be one, but preferably two or more are provided. In the first positive electrode collector 6a, a misalignment prevention hole 6e is provided around the connection hole 6c. The number of misalignment prevention holes 6e may be one, but preferably at least two are provided. The misalignment prevention hole 6e is preferably disposed between the fixing holes 6d and the fixing holes 6d. In addition, the fixing hole 6d preferably has a small diameter portion 6d1 and a large diameter portion 6d2 having an inner diameter larger than the small diameter portion 6d1. The large diameter portion 6d2 is preferably disposed closer to the electrode body 3 than the small diameter portion 6d1.

[0031] As shown in FIG. 8 and FIG. 10A, the second insulating member 63 has an insulating member first region 63x arranged to face the deformable plate 62, an insulating member second region 63y arranged to face the sealing plate 2, and an insulating member third region 63z connecting the insulating member first region 63x and the insulating member second region 63y. An insulating member first opening 63a is provided in the center of the insulating member first region 63x. In the insulating member first region 63x, a third wall portion 63b is provided at an end in the longitudinal direction of the sealing plate 2. A third connection portion 63d is provided on the third wall portion 63b. In addition, in the insulating member first region 63x, a fourth wall portion 63c is provided at both ends in the lateral direction of the sealing plate 2. A fourth connection portion 63e is provided on the fourth wall portion 63c. In addition, four fixing protrusions 63f are provided on the surface of the insulating member first region 63x on the electrode body 3 side. In addition, two misalignment prevention protrusions 63g are provided. Four claw portions 63h are provided on the surface of the insulating member first region 63x facing the sealing plate 2. The insulating member second region 63y is disposed at a position closer to the sealing plate 2 than the insulating member first region 63x. In the insulating member second region 63y, an insulating member second opening 63i is provided at a position facing the electrolyte injection hole 15 provided in the sealing plate 2. An insulating member annular rib 63k extending toward the electrode body 3 is provided on the edge of the insulating member second opening 63i.

[0032] As shown in FIG. 10B, the first positive electrode current collector 6a is placed on the second insulating member 63 so that the fixing protrusion 63f of the second insulating member 63 is placed in the fixing hole 6d of the first positive electrode current collector 6a and the misalignment prevention protrusion 63g of the second insulating member 63 is placed in the misalignment prevention hole 6e of the first positive electrode current collector 6a. Then, the tip of the fixing protrusion 63f of the second insulating member 63 is deformed by thermal caulking or the like. As a result, as shown in FIG. 8C and FIG. 10C, an enlarged diameter portion 63f1 is formed at the tip of the fixing protrusion 63f of the second insulating member 63, and the second insulating member 63 and the first positive electrode current collector 6a are fixed.

[0033] As shown in FIG. 8C, it is preferable that the expanded diameter portion 63f1 formed at the tip of the fixing projection 63f of the second insulating member 63 is disposed within the large diameter portion 6d2 of the fixing hole 6d.

[0034] The misalignment prevention projections 63g of the second insulating member 63 are not thermally caulked, unlike the fixing projections 63f.

[0035] The outer diameter of the fixing protrusion 63f is preferably larger than the outer diameter of the misalignment prevention protrusion 63g. The inner diameter of the small diameter portion 6d1 of the fixing hole 6d of the first positive electrode current collector 6a is preferably larger than the inner diameter of the misalignment prevention hole 6e of the first positive electrode current collector 6a.

[0036] Next, as shown in FIGS. 8A to 8C, the second insulating member 63 to which the first positive electrode current collector 6a is fixed is connected to the first insulating member 10 and the conductive member 61.

[0037] As shown in FIG. 8B, the fourth connection portion 63e of the second insulating member 63 is connected to the first connection portion 10e of the first insulating member 10. Also, as shown in FIG. 8C, the claw portion 63h of the second insulating member 63 is connected to the flange portion 61d of the conductive member 61. As a result, the second insulating member 63 is connected to each of the first insulating member 10 and the conductive member 61. Note that the second insulating member 63 does not necessarily have to be connected to both the first insulating member 10 and the conductive member 61. However, it is preferable that the second insulating member 63 is connected to at least one of the first insulating member 10 and the conductive member 61. As a result, even if a strong impact or vibration is applied to the prismatic secondary battery 20, it is possible to suppress the application of a load to the fragile portion of the first positive electrode collector 6a. Therefore, it is possible to suppress damage or breakage of the fragile portion of the first positive electrode collector 6a.

[0038] The deformation plate 62 is welded to the first positive electrode collector 6a. FIG. 11 is an enlarged view of the vicinity of the connection portion of the deformation plate 62 and the first positive electrode collector 6a in FIG. 8A. As shown in FIG. 11, the second protrusion 62a2 of the deformation plate 62 is disposed in the connection hole 6c of the first positive electrode collector 6a. The second protrusion 62a2 of the deformation plate 62 and the edge of the connection hole 6c of the first positive electrode collector 6a are welded to each other by laser welding or the like. The connection portion of the deformation plate 62 and the first positive electrode collector 6a is formed at a position corresponding to the insulating member first opening 63a of the second insulating member 63.

[0039] In addition, in the first positive electrode collector 6a, a thin portion 6f is provided around the connection hole 6c. The thin portion 6f is provided with an annular notch 6g so as to surround the connection hole 6c. An annular connection rib 6h is formed on the edge of the connection hole 6c. This connection rib 6h is welded to the deformation plate 62. In addition, the first positive electrode collector 6a and the deformation plate 62 may be welded in an annular shape around the entire circumference of the connection hole 6c, or may have a portion that is not welded but is not annular. In addition, the first positive electrode collector 6a and the deformation plate 62 may be welded at a plurality of separated points on the edge of the connection hole 6c.

[0040] Here, the operation of the current interrupt mechanism 60 will be described. When the pressure inside the battery case 100 increases, the deformation plate 62 deforms so that the center part of the deformation plate 62 moves toward the sealing plate 2 side. When the pressure inside the battery case 100 reaches a predetermined value or more, the deformation plate 62 deforms and the notch 6g provided in the thin part 6f of the first positive electrode collector 6a breaks. This cuts off the conductive path from the positive electrode plate 4 to the positive electrode terminal 7. In this way, the current interrupt mechanism 60 includes the first positive electrode collector 6a, the deformation plate 62, and the conductive member 61. When the prismatic secondary battery 20 is in an overcharged state and the pressure inside the battery case 100 increases, the current interrupt mechanism 60 operates and cuts off the conductive path from the positive electrode plate 4 to the positive electrode terminal 7, thereby preventing further progress of overcharging. The operating pressure at which the current interrupt mechanism 60 operates can be determined appropriately.

[0041] Before welding the deformable plate 62 and the first positive electrode current collector 6a, gas is fed into the inside of the conductive member 61 through a terminal through-hole 7c formed in the positive electrode terminal 7, so that a leak inspection can be performed on the welded portion of the conductive member 61 and the deformable plate 62. The terminal through-hole 7c is sealed by a terminal sealing member 7x. The terminal sealing member 7x is preferably made of a metal member 7y and a rubber member 7z.

[0042] Fig. 12 is a perspective view of the sealing plate 2 to which the first insulating member 10, the conductive member 61, the deformable plate 62, the second insulating member 63, and the first positive electrode current collector 6a are attached. As shown in Fig. 12, the second insulating member 63 is provided with a third connection portion 63d at an end portion in the longitudinal direction of the sealing plate 2. The first insulating member 10 is provided with a second connection portion 10f at both ends in the lateral direction of the sealing plate 2. [Installing each part on the sealing plate (negative electrode side)] A method of attaching the negative electrode terminal 9 and the first negative electrode current collector 8a to the sealing plate 2 will be described with reference to FIG. 2 and FIG. 13. The external insulating member 13 is disposed on the outer surface of the battery near the negative electrode terminal mounting hole 2b provided in the sealing plate 2, and the internal insulating member 12 and the first negative electrode current collector 8a are disposed on the inner surface of the battery near the negative electrode terminal mounting hole 2b. Next, the negative electrode terminal 9 is inserted into the through hole of the external insulating member 13, the negative electrode terminal mounting hole 2b of the sealing plate 2, the through hole of the internal insulating member 12, and the through hole of the first negative electrode current collector 8a. Then, the tip of the negative electrode terminal 9 is crimped onto the first negative electrode current collector 8a. As a result, the external insulating member 13, the sealing plate 2, the internal insulating member 12, and the first negative electrode current collector 8a are fixed. It is preferable that the crimped portion of the negative electrode terminal 9 and the first negative electrode current collector 8a are welded and connected by laser welding or the like. Moreover, it is preferable that the inner insulating member 12 and the outer insulating member 13 are each made of resin. [Connection between current collector and tab] FIG. 14 is a diagram showing a method of connecting a positive electrode tab 40 to the second positive electrode current collector 6b and a method of connecting a negative electrode tab 50 to the second negative electrode current collector 8b. Two electrode body elements are prepared by the above-mentioned method, and are respectively the first electrode body element 3a and the second electrode body element 3b. The first electrode body element 3a and the second electrode body element 3b may have exactly the same configuration or may have different configurations. Here, the multiple positive electrode tabs 40 of the first electrode body element 3a constitute the first positive electrode tab group 40a. The multiple negative electrode tabs 50 of the first electrode body element 3a constitute the first negative electrode tab group 50a. The multiple positive electrode tabs 40 of the second electrode body element 3b constitute the second positive electrode tab group 40b. The multiple negative electrode tabs 50 of the second electrode body element 3b constitute the second negative electrode tab group 50b.

[0043] A second positive electrode current collector 6b and a second negative electrode current collector 8b are disposed between the first electrode body element 3a and the second electrode body element 3b. A first positive electrode tab group 40a consisting of a plurality of stacked positive electrode tabs 40 protruding from the first electrode body element 3a is disposed on the second positive electrode current collector 6b, and a first negative electrode tab group 50a consisting of a plurality of stacked negative electrode tabs 50 protruding from the first electrode body element 3a is disposed on the second negative electrode current collector 8b. A second positive electrode tab group 40b consisting of a plurality of stacked positive electrode tabs 40 protruding from the second electrode body element 3b is disposed on the second positive electrode current collector 6b, and a second negative electrode tab group 50b consisting of a plurality of stacked negative electrode tabs 50 protruding from the second electrode body element 3b is disposed on the second negative electrode current collector 8b. The first positive electrode tab group 40a and the second positive electrode tab group 40b are each connected to the second positive electrode current collector 6b by welding to form a welded connection 90. The first negative electrode tab group 50a and the second negative electrode tab group 50b are each connected to the second negative electrode current collector 8b by welding to form a welded connection 90. The welded connection can be performed as follows.

[0044] The stacked tabs (first positive electrode tab group 40a, second positive electrode tab group 40b, first negative electrode tab group 50a, second negative electrode tab group 50b) and the current collectors (second positive electrode current collector 6b, second negative electrode current collector 8b) are sandwiched by welding jigs from above and below, and welding is performed. The welding method here is preferably ultrasonic welding or resistance welding. Note that the pair of welding jigs is a pair of resistance welding electrodes in the case of resistance welding, and a horn and anvil in the case of ultrasonic welding. Note that the tabs (first positive electrode tab group 40a, second positive electrode tab group 40b, first negative electrode tab group 50a, second negative electrode tab group 50b) and the current collectors (second positive electrode current collector 6b, second negative electrode current collector 8b) can also be connected by laser welding.

[0045] As shown in FIG. 14, the second positive electrode current collector 6b has a current collector first region 6b1 and a current collector second region 6b2. The positive electrode tab 40 is connected to the current collector first region 6b1. The current collector first region 6b1 is provided with a current collector second opening 6z. The current collector first region 6b1 and the current collector second region 6b2 are connected by a current collector third region 6b3. After the second positive electrode current collector 6b is connected to the first positive electrode current collector 6a, the current collector second opening 6z is disposed at a position corresponding to the electrolyte injection hole 15 provided in the sealing plate 2. The current collector second region 6b2 is provided with a current collector first opening 6y. A current collector first recess 6m is provided around the current collector first opening 6y. In addition, target holes 6k are provided on both sides of the current collector first opening 6y in the short-side direction of the sealing plate 2.

[0046] As shown in Fig. 14, the second negative electrode current collector 8b has a current collector first region 8b1 and a current collector second region 8b2. A negative electrode tab 50 is connected to the current collector first region 8b1. A current collector first opening 8y is provided in the current collector second region 8b2. A current collector first recess 8f is provided around the current collector first opening 8y. In addition, target holes 8e are provided on both sides of the current collector first opening 8y in the short-side direction of the sealing plate 2. [Connection between the first positive electrode collector and the second positive electrode collector] As shown in FIG. 2, FIG. 7, FIG. 8, etc., the second positive electrode collector 6b is disposed on the second insulating member 63 so that the collector protrusion 6x of the first positive electrode collector 6a is positioned within the collector first opening 6y of the second positive electrode collector 6b. Then, the collector protrusion 6x of the first positive electrode collector 6a and the edge of the collector first opening 6y of the second positive electrode collector 6b are welded by irradiating an energy beam such as a laser. This connects the first positive electrode collector 6a and the second positive electrode collector 6b. Note that it is preferable that the first positive electrode collector 6a and the second positive electrode collector 6b are welded and connected in the collector first recess 6m.

[0047] 2 and 8, the distance between the sealing plate 2 and the current collector first region 6b1 is smaller than the distance between the sealing plate 2 and the current collector second region 6b2 in the direction perpendicular to the sealing plate 2. With this configuration, the space occupied by the current collecting portion can be made smaller, resulting in a prismatic secondary battery with a higher volumetric energy density.

[0048] When the first positive electrode collector 6a and the second positive electrode collector 6b are welded together by irradiation with an energy beam such as a laser, it is preferable to use the target hole 6k as a target for image correction.

[0049] As shown in Fig. 8A, a collector second recess 6w is formed on the surface of the first positive electrode collector 6a facing the second insulating member 63, on the back side of the collector protrusion 6x. This is preferable because it makes it easier to form a larger welded connection between the first positive electrode collector 6a and the second positive electrode collector 6b. In addition, the formation of the collector second recess 6w can prevent the second insulating member 63 from being damaged by heat during welding when the first positive electrode collector 6a and the second positive electrode collector 6b are welded together.

[0050] [Connection between the first negative electrode current collector and the second negative electrode current collector] 13, the second negative electrode current collector 8b has a current collector first region 8b1 and a current collector second region 8b2. A negative electrode tab 50 is connected to the current collector first region 8b1. A current collector first opening 8y is provided in the current collector second region 8b2. The current collector first region 8b1 and the current collector second region 8b2 are connected by a current collector third region 8b3.

[0051] As shown in FIG. 13, the second negative electrode current collector 8b is disposed on the inner insulating member 12 such that the collector protrusion 8x of the first negative electrode current collector 8a is positioned within the collector first opening 8y of the second negative electrode current collector 8b. Then, the collector protrusion 8x of the first negative electrode current collector 8a and the edge of the collector first opening 8y of the second negative electrode current collector 8b are welded by irradiating an energy beam such as a laser. This connects the first negative electrode current collector 8a and the second negative electrode current collector 8b. It is preferable that the first negative electrode current collector 8a and the second negative electrode current collector 8b are welded and connected in the collector first recess 8f. The second negative electrode current collector 8b is provided with a target hole 8e in the same manner as the second positive electrode current collector 6b. In a direction perpendicular to the sealing plate 2, the distance between the sealing plate 2 and the current collector first region 8b1 is smaller than the distance between the sealing plate 2 and the current collector second region 8b2. Note that the second negative electrode current collector 8b can be connected to the negative electrode terminal 9 without using the first negative electrode current collector 8a.

[0052] As shown in Fig. 13, a collector second recess 8w is formed on the surface of the first negative electrode collector 8a facing the inner insulating member 12 and on the back side of the collector protrusion 8x. This is preferable because it makes it easier to form a larger welded connection between the first negative electrode collector 8a and the second negative electrode collector 8b. In addition, the formation of the collector second recess 8w can prevent the inner insulating member 12 from being damaged by heat during welding when the first negative electrode collector 8a and the second negative electrode collector 8b are welded together.

[0053] It is preferable that the current-collector protrusions 6x and the current-collector protrusions 8x each have a non-circular shape in a plan view, and preferably have a rectangular, elliptical or track-like shape. [Bending the tab and preparing the electrode body] 15A to 15C are diagrams showing a process of arranging the second positive electrode current collector 6b, to which the first positive electrode tab group 40a of the first electrode body element 3a and the second positive electrode tab group 40b of the second electrode body element 3b are connected, on the sealing plate 2 via the second insulating member 63.

[0054] As shown in FIG. 15A, the second insulating member 63 is disposed on the inner surface side of the sealing plate 2 facing the battery. Here, the second insulating member 63 has a base portion 630a (corresponding to the insulating member second region 63y described above). In the base portion 630a, a first wall portion 630b extending in a direction away from the sealing plate 2 is provided at one end in the short-side direction of the sealing plate 2, and a second wall portion 630c extending in a direction away from the sealing plate 2 is provided at the other end in the short-side direction of the sealing plate 2. In the base portion 630a, an insulating member second opening 63i is provided at a position facing the electrolyte injection hole 15 of the sealing plate 2. Around the insulating member second opening 63i, an insulating member annular rib 63k extending in a direction away from the sealing plate 2 is provided.

[0055] Next, as shown in FIG. 15B, the second positive electrode current collector 6b is placed on the sealing plate 2 via the second insulating member 63. The base portion 630a of the second insulating member 63 is placed between the second positive electrode current collector 6b and the sealing plate 2. The first wall portion 630b and the second wall portion 630c are each in a state of protruding in a direction away from the sealing plate 2 from the surface of the second positive electrode current collector 6b to which the first positive electrode tab group 40a and the second positive electrode tab group 40b are connected. After the state of FIG. 15B is achieved, the second positive electrode current collector 6b is welded and connected to the first positive electrode current collector 6a.

[0056] 15C, the first positive electrode tab group 40a and the second positive electrode tab group 40b are curved so as to gather the first electrode body element 3a and the second electrode body element 3b into one. Here, the first positive electrode tab group 40a and the second positive electrode tab group 40b are curved in different directions.

[0057] The first positive electrode tab group 40a is connected to a region of the second positive electrode current collector 6b that is arranged along the sealing plate 2. The tip of the first positive electrode tab group 40a is located on the central side in the short-side direction of the sealing plate 2. The first positive electrode tab group 40a is bent near the first wall portion 630b and connected to each positive electrode plate. The outer surface of the first positive electrode tab group 40a on the first wall portion 630b side is in contact with the inner surface of the first wall portion 630b (the side surface on the central side in the short-side direction of the sealing plate 2).

[0058] The second positive electrode tab group 40b is connected to a region of the second positive electrode current collector 6b that is arranged along the sealing plate 2. The tip of the second positive electrode tab group 40b is located on the central side in the short-side direction of the sealing plate 2. The second positive electrode tab group 40b is bent near the second wall portion 630c and connected to each positive electrode plate. The outer surface of the second positive electrode tab group 40b on the second wall portion 630c side is in contact with the inner surface of the second wall portion 630c (the side surface on the central side in the short-side direction of the sealing plate 2).

[0059] The outer surface of the first positive electrode tab group 40a on the first wall portion 630b side is in contact with the inner surface of the first wall portion 630b, and the outer surface of the second positive electrode tab group 40b on the second wall portion 630c side is in contact with the inner surface of the second wall portion 630c. With this configuration, the curved first positive electrode tab group 40a to the second positive electrode tab group 40b are curved into an intended shape. Therefore, the curved first positive electrode tab group 40a to the second positive electrode tab group 40b can be more effectively prevented from protruding outward in the short-side direction of the sealing plate 2, curving into an unintended shape, or bending. For example, if the first positive electrode tab group 40a to the second positive electrode tab group 40b protrude outward in the short-side direction of the sealing plate 2, or curved or bent into an unintended shape, the positive electrode tab 40 may be broken or damaged, or may cause an unintended short circuit. Furthermore, the first positive electrode tab group 40a to the second positive electrode tab group 40b that protrude outward in the short-side direction of the sealing plate 2 may reduce the ease of insertion when inserting the electrode body 3 into the rectangular exterior body 1.

[0060] The negative electrode side is preferably configured similarly to the positive electrode side. The inner insulating member 12 is preferably provided with a base portion disposed between the sealing plate 2 and the second negative electrode current collector 8b, and a wall portion provided on the base portion and extending in a direction away from the sealing plate 2. The first negative electrode tab group 50a and the second negative electrode tab group 50b are preferably brought into contact with the inner surfaces of the wall portions.

[0061] It is preferable to bundle the first electrode body element 3a and the second electrode body element 3b together with tape or the like. Alternatively, it is preferable to bundle the first electrode body element 3a and the second electrode body element 3b together by placing them in an insulating sheet 14 formed into a box or bag shape. Alternatively, it is preferable to fix the first electrode body element 3a and the second electrode body element 3b by adhesion. [Installing the cover] After connecting the second positive electrode collector 6b to the first positive electrode collector 6a and connecting the second negative electrode collector 8b to the first negative electrode collector 8a, it is preferable to connect a resin cover portion 80 to the first insulating member 10 and the second insulating member 63 before assembling the first electrode body element 3a and the second electrode body element 3b together. The cover portion 80 is not an essential component and can be omitted. As shown in FIG. 2, in the prismatic secondary battery 20, the cover portion 80 is disposed between the first positive electrode collector 6a and the electrode body 3. The cover portion 80 is connected to the second connection portion 10f of the first insulating member 10 and the third connection portion 63d of the second insulating member 63. It is preferable that the cover portion 80 is connected to at least one of the first insulating member 10 and the second insulating member 63. [Regarding prismatic secondary battery 20] FIG. 16 is a cross-sectional view of the vicinity of the sealing plate 2 taken along the line XVI-XVI in FIG. The first positive electrode tab group 40a and the second positive electrode tab group 40b are each curved, and are connected to a portion of the second positive electrode current collector 6b that is disposed along the sealing plate 2. Due to this configuration, the prismatic secondary battery 20 becomes a prismatic secondary battery with a higher volumetric energy density.

[0062] The second insulating member 63 as an insulating member has a base portion 630a arranged between the sealing plate 2 and the second positive electrode current collector 6b as a positive electrode current collector, and a first wall portion 630b protruding from one end of the base portion 630a in the short direction of the sealing plate 2 toward the electrode body 3. The first wall portion 630b is arranged between the first positive electrode tab group 40a and the side surface of the rectangular exterior body 1 that is closer to the first positive electrode tab group 40a (the left side surface in FIG. 16). This results in a structure in which the first positive electrode tab group 40a and the rectangular exterior body 1 are less likely to come into direct contact with each other. This results in a more reliable rectangular secondary battery.

[0063] The base portion 630a of the second insulating member 63 as an insulating member has a second wall portion 630c that protrudes from the other end in the short direction of the sealing plate 2 toward the electrode body 3. The second wall portion 630c is disposed between the second positive electrode tab group 40b and the side surface of the rectangular exterior body 1 that is closer to the second positive electrode tab group 40b (the left side surface in FIG. 16). This results in a structure in which the second positive electrode tab group 40b and the rectangular exterior body 1 are less likely to come into direct contact with each other. This results in a more reliable rectangular secondary battery.

[0064] The outer surface of the first positive electrode tab group 40a on the first wall portion 630b side is in contact with the inner surface of the first wall portion 630b. With this configuration, it is possible to prevent the first positive electrode tab group 40a from taking on an unintended shape. This makes it possible to more effectively prevent the positive electrode tabs 40 constituting the first positive electrode tab group 40a from being broken or damaged. Alternatively, it is possible to more effectively prevent the occurrence of an unexpected short circuit between positive and negative electrodes.

[0065] The outer surface of the second positive electrode tab group 40b on the second wall portion 630c side is in contact with the inner surface of the second wall portion 630c. With this configuration, it is possible to prevent the second positive electrode tab group 40b from taking on an unintended shape. This makes it possible to more effectively prevent the positive electrode tabs 40 constituting the second positive electrode tab group 40b from being broken or damaged. Alternatively, it is possible to more effectively prevent the occurrence of an unexpected short circuit between positive and negative electrodes.

[0066] As shown in FIG. 16, the end of the insulating sheet 14 on the sealing plate 2 side is preferably located closer to the sealing plate 2 than the lower end of the first wall portion 630b. That is, the insulating sheet 14 preferably extends from between the rectangular outer casing 1 and the electrode body 3 to between the rectangular outer casing 1 and the first wall portion 630b. Also, the end of the insulating sheet 14 on the sealing plate 2 side is preferably located closer to the sealing plate 2 than the lower end of the second wall portion 630c. That is, the insulating sheet 14 preferably extends from between the rectangular outer casing 1 and the electrode body 3 to between the rectangular outer casing 1 and the second wall portion 630c. This results in a state in which the insulating sheet 14 and the first wall portion 630b overlap in the short-side direction of the sealing plate 2, and also in a state in which the insulating sheet 14 and the second wall portion 630c overlap in the short-side direction of the sealing plate 2. This more reliably prevents the first positive electrode tab group 40a to the second positive electrode tab group 40b from coming into direct contact with the rectangular exterior body 1. In addition, in the short-side direction of the sealing plate 2, the thickness of the first wall portion 630b and the thickness of the second wall portion 630c are preferably greater than the thickness of the insulating sheet 14.

[0067] 16, in the short-side direction of the sealing plate 2, the distance between the rectangular outer casing 1 and the first wall portion 630b is greater than the distance between the rectangular outer casing 1 and the electrode body 3. In addition, in the short-side direction of the sealing plate 2, the distance between the rectangular outer casing 1 and the second wall portion 630c is greater than the distance between the rectangular outer casing 1 and the electrode body 3. With this configuration, it is possible to more reliably prevent the first positive electrode tab group 40a to the second positive electrode tab group 40b from coming into direct contact with the rectangular outer casing 1.

[0068] In addition, the positive electrode current collector 6 is composed of a first positive electrode current collector 6a and a second positive electrode current collector 6b, and the first positive electrode tab group 40a and the second positive electrode tab group 40b are connected to the second positive electrode current collector. This makes it possible to fabricate a prismatic secondary battery having a higher volumetric energy density by a simpler method.

[0069] As shown in Fig. 17, a first recess 2c is provided on the surface of the sealing plate 2 facing the electrode body 3. In addition, as shown in Fig. 6, a first protrusion 70 is provided on a portion of the second insulating member 63 facing the sealing plate 2. In the prismatic secondary battery 20, the first protrusion 70 is disposed within the first recess 2c. This makes it possible to prevent the second insulating member 63 from being significantly misaligned with respect to the sealing plate 2 within a plane parallel to the sealing plate 2.

[0070] The shapes of the first protrusion 70 and the first recess 2c are not particularly limited. When viewed from a direction perpendicular to the sealing plate 2, the shape of the first protrusion 70 is preferably circular. When viewed from a direction perpendicular to the sealing plate 2, the shape of the first recess 2c is preferably circular, and more preferably elliptical.

[0071] The difference in width between the first recess 2c and the first protrusion 70 in the short-side direction of the sealing plate 2 is preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less.

[0072] When viewed from a direction perpendicular to the sealing plate 2, the width of the first recess 2c in the longitudinal direction of the sealing plate 2 is preferably larger than the width of the first recess 2c in the lateral direction of the sealing plate 2.

[0073] It is preferable that the difference between the width of the first recess 2c and the width of the first protrusion 70 in the longitudinal direction of the sealing plate 2 is larger than the difference between the width of the first recess 2c and the width of the first protrusion 70 in the lateral direction of the sealing plate 2. With this configuration, it is possible to suppress misalignment of the second insulating member 63 with respect to the sealing plate 2 in the lateral direction of the sealing plate 2, and it is also possible to easily assemble the second insulating member 63 to the sealing plate 2.

[0074] The shape of the first convex portion 70 and the first concave portion 2c in a plan view is preferably linear or dot-like, and is more preferably dot-like.

[0075] In the longitudinal direction of the sealing plate 2, the first recess 2c is preferably disposed between the gas exhaust valve 17 and the electrolyte injection hole 15. In the longitudinal direction of the sealing plate 2, the second insulating member 63 is preferably connected to other components on the positive electrode terminal 7 side of the electrolyte injection hole 15. With this configuration, the second insulating member 63 is directly or indirectly connected to the sealing plate 2 at a plurality of locations farther apart, so that the second insulating member 63 can be more effectively prevented from shifting relative to the sealing plate 2 in a plane parallel to the sealing plate 2. In the prismatic secondary battery 20, the second insulating member 63 is connected to the first insulating member 10 fixed to the sealing plate 2. In addition, the second insulating member 63 is fixed to the conductive member 61 fixed to the sealing plate 2 via the first insulating member 10 and the positive electrode terminal 7.

[0076] In the short-side direction of the sealing plate 2, the first recess 2c is preferably shifted toward the end of the sealing plate 2 from the center of the sealing plate 2. With this configuration, even when the first recess 2c is provided in the sealing plate 2, a decrease in the strength of the sealing plate 2 can be suppressed. Therefore, the sealing plate 2 becomes less likely to deform.

[0077] In the prismatic secondary battery 20, the second insulating member 63 is disposed between the deformable plate 62 and the first positive electrode current collector 6a, and has an insulating member first region 63x fixed to the first positive electrode current collector 6a, and an insulating member second region 63y disposed on the sealing plate 2. A first convex portion is formed in the insulating member second region of the second insulating member 63. This can prevent the second insulating member 63 from shifting relative to the sealing plate 2, thereby preventing a load from being applied to the fragile portion of the current interrupt mechanism 60. Alternatively, it can prevent the first positive electrode tab group 40a to the second positive electrode tab group 40b from being damaged.

[0078] The depth of the first recess 2c is preferably 30% to 70% of the thickness of the sealing plate 2 around the first recess 2c. In addition, in the short-side direction of the sealing plate 2, the distance from the center of the sealing plate 2 to the first recess 2c is preferably 1 / 10 or more of the length of the sealing plate 2, more preferably 1 / 8 or more, and even more preferably 1 / 5 or more.

[0079] As shown in Fig. 17, a second recess 2d is provided on the surface of the sealing plate 2 facing the electrode body 3. In addition, as shown in Fig. 6, a second protrusion 71 is provided on a portion of the first insulating member 10 facing the sealing plate 2. In the prismatic secondary battery 20, the second protrusion 71 is disposed within the second recess 2d. This makes it possible to prevent the first insulating member 10 from being significantly misaligned with respect to the sealing plate 2 within a plane parallel to the sealing plate 2.

[0080] The shapes of the second protrusion 71 and the second recess 2d are not particularly limited. When viewed from a direction perpendicular to the sealing plate 2, the shape of the second protrusion 71 is preferably circular. When viewed from a direction perpendicular to the sealing plate 2, the shape of the second recess 2d is preferably circular, and more preferably elliptical.

[0081] The difference in width between the second recess 2d and the second protrusion 71 in the short-side direction of the sealing plate 2 is preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less.

[0082] The second convex portion 71 and the second concave portion 2d preferably have a linear or dotted shape in plan view, and more preferably have a dotted shape.

[0083] The second insulating member 63, which is disposed between the deformable plate 62 and the first positive electrode current collector 6a and fixed to the first positive electrode current collector 6a, is preferably connected to the first insulating member 10. In such a case, by disposing the second convex portion 71 provided on the first insulating member 10 in the second concave portion 2d provided on the sealing plate 2 and preventing the first insulating member 10 from being significantly displaced relative to the sealing plate 2, it is possible to more effectively prevent a load from being applied to the fragile portion of the current-interrupt mechanism 60.

[0084] In the longitudinal direction of the sealing plate 2, the second recess 2d is preferably disposed outside the positive electrode terminal mounting hole 2a. With this configuration, a decrease in the strength of the sealing plate 2 can be suppressed compared to a case in which the second recess 2d is provided inside the positive electrode terminal mounting hole 2a in the longitudinal direction of the sealing plate 2. In addition, in the lateral direction of the sealing plate 2, the second recess 2d is preferably disposed closer to the end of the sealing plate 2 than the center of the sealing plate 2. In addition, when the first recess 2c is formed in the sealing plate 2, it is preferable that the first recess 2c is formed on one side of the center of the sealing plate 2 and the second recess 2d is formed on the other side of the center of the sealing plate 2 in the lateral direction of the sealing plate 2.

[0085] The depth of the second recess 2d is preferably 30% to 70% of the thickness of the sealing plate 2 around the second recess 2d. In addition, in the short-side direction of the sealing plate 2, the distance from the center of the sealing plate 2 to the second recess 2d is preferably 1 / 10 or more of the length of the sealing plate 2, more preferably 1 / 8 or more, and even more preferably 1 / 5 or more.

[0086] As shown in Fig. 17, a third recess 2e is provided on the surface of the sealing plate 2 facing the electrode body 3. As shown in Fig. 18, a third protrusion 72 is provided on a portion of the inner insulating member 12 arranged between the sealing plate 2 and the second negative electrode current collector 8b, facing the sealing plate 2. In the prismatic secondary battery 20, the third protrusion 72 is disposed within the third recess 2e. This makes it possible to prevent the inner insulating member 12 from being significantly misaligned with respect to the sealing plate 2 in a plane parallel to the sealing plate 2.

[0087] The shapes of the third protrusion 72 and the third recess 2e are not particularly limited. When viewed from a direction perpendicular to the sealing plate 2, the shape of the third protrusion 72 is preferably circular. When viewed from a direction perpendicular to the sealing plate 2, the shape of the third recess 2e is preferably circular, and more preferably elliptical.

[0088] The difference in width between the third recess 2e and the third protrusion 72 in the short-side direction of the sealing plate 2 is preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less.

[0089] When viewed in a direction perpendicular to the sealing plate 2, it is preferable that the width of the third recess 2e in the longitudinal direction of the sealing plate 2 be greater than the width of the third recess 2e in the lateral direction of the sealing plate 2.

[0090] It is preferable that the difference between the width of the third recess 2e and the width of the third protrusion 72 in the longitudinal direction of the sealing plate 2 is larger than the difference between the width of the third recess 2e and the width of the third protrusion 72 in the lateral direction of the sealing plate 2. With this configuration, it is possible to suppress misalignment of the inner insulating member 12 with respect to the sealing plate 2 in the lateral direction of the sealing plate 2, and it is also possible to easily assemble the inner insulating member 12 to the sealing plate 2.

[0091] The shape of the third convex portion 72 and the third concave portion 2e in a plan view is preferably linear or dot-like, and more preferably dot-like. In the short-side direction of the sealing plate 2, the third recess 2e is preferably shifted toward the end of the sealing plate 2 from the center of the sealing plate 2. With this configuration, even when the sealing plate 2 has the third recess 2e, a decrease in the strength of the sealing plate 2 can be suppressed.

[0092] In the short-side direction of the sealing plate 2, it is preferable that the first recess 2c having the first protrusion 70 disposed therein, which is provided on the second insulating member 63 arranged between the sealing plate 2 and the second positive electrode current collector 6b, is located on one side of the center of the sealing plate 2, and the third recess 2e having the third protrusion 72 disposed therein, which is provided on the inner insulating member 12 arranged between the sealing plate 2 and the second negative electrode current collector 8b, is located on the other side of the center of the sealing plate 2. With such a configuration, it is possible to prevent the strength of the sealing plate 2 from decreasing. [Variation 1] The prismatic secondary battery according to Modification 1 has a similar configuration to the prismatic secondary battery 20 according to the above-described embodiment, except that the first positive electrode tab group 40a and the second positive electrode tab group 40b have different shapes. Fig. 19 is a cross-sectional view of the prismatic secondary battery according to Modification 1, corresponding to Fig. 16. Fig. 20 is an enlarged view of the vicinity of the first positive electrode tab group 40a in Fig. 19. Fig. 21 is an enlarged view of the vicinity of the second positive electrode tab group 40b in Fig. 19.

[0093] The first positive electrode tab group 40a and the second positive electrode tab group 40b are each curved, and are connected to a portion of the second positive electrode current collector 6b that is disposed along the sealing plate 2. This configuration results in a prismatic secondary battery with a higher volumetric energy density.

[0094] The second insulating member 63 as an insulating member has a base portion 630a arranged between the sealing plate 2 and the second positive electrode current collector 6b as a current collecting member, and a first wall portion 630b protruding from one end of the base portion 630a in the short direction of the sealing plate 2 toward the electrode body 3. The first wall portion 630b is arranged between the first positive electrode tab group 40a and the rectangular exterior body 1. This results in a structure in which the first positive electrode tab group 40a and the rectangular exterior body 1 are unlikely to come into direct contact with each other. This results in a more reliable rectangular secondary battery.

[0095] A base portion 630a of the second insulating member 63 serving as an insulating member is provided with a second wall portion 630c that protrudes from the other end in the short direction of the sealing plate 2 toward the electrode body 3. The second wall portion 630c is disposed between the second positive electrode tab group 40b and the rectangular exterior body 1. This results in a structure in which the second positive electrode tab group 40b and the rectangular exterior body 1 are less likely to come into direct contact with each other. This results in a more reliable rectangular secondary battery.

[0096] In addition, the positive electrode current collector 6 is composed of a first positive electrode current collector 6a and a second positive electrode current collector 6b, and the first positive electrode tab group 40a and the second positive electrode tab group 40b are connected to the second positive electrode current collector. This makes it possible to fabricate a prismatic secondary battery having a higher volumetric energy density by a simpler method.

[0097] 20, the first positive electrode tab group 40a has a first connection region 500 arranged on the second positive electrode current collector 6b, and a first curved region 501 that extends from an end of the first connection region 500 on the first wall portion 630b side toward the electrode body 3 and curves so as to bulge toward the first wall portion 630b. A first recessed region 502 that is recessed toward the center of the sealing plate 2 in the short side direction of the sealing plate 2 (to the right in FIG. 20) is provided in the electrode body 3 of the first curved region 501 on the surface of the first positive electrode tab group 40a on the rectangular exterior body 1 side.

[0098] 21, the second positive electrode tab group 40b has a second connection region 503 arranged on the second positive electrode current collector 6b, and a second curved region 504 that extends from an end of the second connection region 503 on the second wall portion 630c side toward the electrode body 3 and curves so as to bulge toward the second wall portion 630c. A second recessed region 505 that is recessed toward the center of the sealing plate 2 in the short side direction of the sealing plate 2 (left side in FIG. 21) is provided in the electrode body 3 of the second curved region 504 on the surface of the second positive electrode tab group 40b on the rectangular exterior body 1 side.

[0099] In the short-side direction of sealing plate 2 (left-right direction in FIG. 19), when the distance between the portion of first curved region 501 located closest to rectangular exterior body 1 and the portion of second curved region 504 located closest to rectangular exterior body 1 is D1 and the distance between first wall portion 630b and second wall portion 630c is D2, it is preferable that D2 ≧ D1. With this configuration, direct contact of first positive electrode tab group 40a to second positive electrode tab group 40b with the rectangular exterior body 1 can be more reliably prevented.

[0100] The outer surface of the first curved region 501 may be in contact with the first wall portion 630b. The outer surface of the second curved region 504 may be in contact with the second wall portion 630c. With such a configuration, it is possible to more effectively prevent the first positive electrode tab group 40a to the second positive electrode tab group 40b from being formed into an unintended shape. Therefore, it is possible to more effectively prevent the positive electrode tabs 40 constituting the first positive electrode tab group 40a to the second positive electrode tab group 40b from being broken or damaged. Alternatively, it is possible to more effectively prevent the occurrence of an unexpected short circuit between positive and negative electrodes.

[0101] In the prismatic secondary battery 20 according to the embodiment described above, an example has been shown in which the second insulating member 63 has a base portion 630a, a first wall portion 630b, and a second wall portion 630c that are disposed between the sealing plate 2 and the second positive electrode current collector 6b. Instead of providing the second insulating member 63 with a base portion and a wall portion, the first insulating member 10 may have a base portion that is disposed between the sealing plate 2 and the second positive electrode current collector 6b, and a wall portion that extends from the base portion to the electrode body 3 side.

[0102] In the prismatic secondary battery 20 according to the embodiment described above, an example has been shown in which the base portion 630a is provided with the first wall portion 630b and the second wall portion 630c. However, only one of the first wall portion 630b and the second wall portion 630c may be provided. It is preferable to provide both the first wall portion 630b and the second wall portion 630c on the base portion 630a.

[0103] In the prismatic secondary battery 20 according to the embodiment described above, the positive electrode tabs 40 are divided into the first positive electrode tab group 40a and the second positive electrode tab group 40b, but they may be one tab group. It is preferable to provide the first positive electrode tab group 40a and the second positive electrode tab group 40b.

[0104] Although the prismatic secondary battery 20 according to the above embodiment has a current interruption mechanism 60, it is not necessary to provide the current interruption mechanism 60. When the current interruption mechanism 60 is not provided, the positive electrode side can have the same configuration as the negative electrode side of the prismatic secondary battery 20.

[0105] In the prismatic secondary battery 20 according to the above embodiment, the positive current collecting member is made up of two components, the first positive current collector 6a and the second positive current collector 6b, but the positive current collecting member can be made up of one component. Also, in the prismatic secondary battery 20 according to the above embodiment, the negative current collecting member is made up of two components, the first negative current collector 8a and the second negative current collector 8b, but the negative current collecting member can be made up of one component.

[0106] In the prismatic secondary battery 20 according to the embodiment described above, the first positive electrode tab group 40a and the second positive electrode tab group 40b, and the first negative electrode tab group 50a and the second negative electrode tab group 50b are curved in different directions. However, the present invention is not limited to this, and the first positive electrode tab group 40a and the second positive electrode tab group 40b may be curved in the same direction, and the first negative electrode tab group 50a and the second negative electrode tab group 50b may be curved in the same direction.

[0107] In the rectangular secondary battery 20 according to the above-described embodiment, an example has been shown in which the positive electrode terminal 7 and the negative electrode terminal 9 are insulated from the sealing plate 2, but one of the positive electrode terminal 7 and the negative electrode terminal 9 can be electrically connected to the sealing plate 2.

[0108] The gas exhaust valve 17 provided in the sealing plate 2 is preferably a thin-walled portion provided in the sealing plate 2. Such a thin-walled portion serving as the gas exhaust valve 17 is formed, for example, by press molding. Alternatively, a through hole may be provided in the sealing plate 2, the through hole may be blocked with a thin-walled valve body, and the valve body may be connected to the sealing plate 2 by welding. <Other> The portion to be broken due to the deformation of the deformable plate is preferably a weak portion provided in the current collecting member, a connection portion between the current collecting member and the deformable plate, or a weak portion provided in the deformable plate. The weak portion is preferably a thin portion, a notch, or the like.

[0109] The first insulating member, the second insulating member, and the cover are preferably made of resin, for example, polypropylene, polyethylene, perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), or the like.

[0110] In the above-described embodiment, the electrode body 3 is composed of two electrode body elements 3a and 3b, but the present invention is not limited to this. The electrode body 3 may be a single laminated electrode body. The electrode body 3 may be a single wound electrode body in which a long positive electrode plate and a long negative electrode plate are wound with a separator interposed therebetween. The two electrode body elements 3a and 3b are not limited to being laminated electrode bodies, and may be wound electrode bodies in which a long positive electrode plate and a long negative electrode plate are wound with a separator interposed therebetween.

[0111] In the case where the electrode body is a laminated electrode body having a plurality of positive plates and a plurality of negative plates, or in the case where the electrode body is a wound electrode body and is arranged so that the winding axis is perpendicular to the sealing plate, it is preferable that the end of the positive plate, the end of the negative plate, and the end of the separator are located on the sealing plate side in the electrode body. With such a configuration, when an electrolyte injection hole is provided in the sealing plate, the electrolyte injection property into the electrode body is improved. In such a case, it is preferable that the sealing plate side end of the separator protrudes toward the sealing plate 2 side more than the sealing plate side end of the negative electrode active material mixture layer in the negative electrode plate. Also, it is preferable that the sealing plate side end of the separator protrudes toward the sealing plate side more than the sealing plate side end of the positive electrode active material mixture layer in the positive electrode plate. Also, it is preferable that the positive electrode plate and the separator are bonded by an adhesive layer, and the negative electrode plate and the separator are bonded by an adhesive layer. With this configuration, it is possible to reliably prevent the positive electrode active material layer and the negative electrode active material layer from coming into contact with the second insulating member and being damaged. [Explanation of symbols]

[0112] 20 Prismatic secondary battery 1...Rectangular exterior body 2...Sealing plate 2a Positive terminal mounting hole 2b Negative terminal mounting hole 2c...First recess 2d: Second recess 2e Third recess 100···Battery case 3...Electrode body 3a...First electrode body element 3b Second electrode body element 4. Positive electrode plate 4a...Positive electrode core 4b Positive electrode active material mixture layer 4d...Positive electrode protective layer 40 Positive electrode tab 40a: First positive electrode tab group 40b Second positive electrode tab group 500 First connection area 501...First curved region 502: First recessed area 503 Second connection area 504...Second curved region 505...Second recess area 5 Negative electrode plate 5a...Negative electrode core 5b Negative electrode active material mixture layer 50 Negative electrode tab 50a...First negative electrode tab group 50b Second negative electrode tab group 6 Positive electrode current collecting member 6a...First positive electrode current collector 6c Connection hole 6d...Fixing hole 6d1...Small diameter part 6d2...Large diameter section 6e Hole for preventing slippage 6f Thin section 6g...notch 6h...connecting rib 6x...Current collector protrusion 6w... Current collector second recess 6b...Second positive electrode current collector 6b1... Current collector first region 6b2... Current collector second area 6b3...Current collector third area 6k target hole 6m... Current collector first recess 6y... First opening of current collector 6z... 2nd opening of current collector 7 Positive terminal 7a...Tsubabe 7b Insertion part 7c...Terminal through hole 7x...Terminal sealing material 7y Metal parts 7z Rubber parts 8. Negative electrode current collecting member 8a...First negative electrode current collector 8x...Current collector protrusion 8w···Current collector second recess 8b...Second negative electrode current collector 8b1... Current collector first area 8b2... Current collector second area 8b3...Current collector third area 8e Target hole 8f... First recess of current collector 8y...Current collector first opening 9...Negative terminal 10... First insulating member 10a... First insulating member body 10b...1st side wall 10c...Second side wall 10d...Second terminal insertion hole 10e···First connection part 10f...Second connection part 10g···Concave 10x...First groove 10y...Second groove 11...External insulating member 11a...First terminal insertion hole 12...Inner insulating member 13 External insulating member 14. Insulation sheet 15...Electrolyte injection hole 16....Sealing plug 17 Gas exhaust valve 60...Current interruption mechanism 61...Conductive member 61a...Conductive member base portion 61b...Tubular part 61c Third terminal insertion hole 61d Flange part 61e Pressing protrusion 61f Conductive member opening 62... Deformed plate 62a...Stepped protrusion 62a1...1st protrusion 62a2...Second protrusion 62b Annular rib 62c: Annular thin-walled section 63... Second insulating member 63x Insulating member first area 63a... Insulating member first opening 63b...Third wall section 63c...4th wall section 63d...Third connection part 63e... 4th connection part 63f...Fixing protrusion 63f1... Expanded diameter part 63g···Protrusions to prevent slippage 63h...Claw part 63y Insulating member second region 63i Insulating member second opening 63k···Insulating member annular rib 630a···Base part 630b...1st wall section 630c...Second wall section 63z Insulating member third area 70···First protrusion 71...Second protrusion 72...Third protrusion 80 Cover part 90... Welded connection

Claims

1. An electrode assembly including a positive electrode plate and a negative electrode plate; A rectangular exterior body having an opening and housing the electrode assembly; a sealing plate that seals the opening and has a longitudinal direction and a lateral direction; an electrolyte injection hole provided in the sealing plate; A tab provided on the positive electrode plate or the negative electrode plate; a tab group consisting of a plurality of the tabs; a terminal electrically connected to the tab group and attached to the sealing plate; a current collecting member electrically connected to the tab group and the terminal; an insulating member disposed between the sealing plate and the current collecting member, The electrode body includes a first electrode body element including a positive electrode plate and a negative electrode plate, and a second electrode body element including a positive electrode plate and a negative electrode plate, The first electrode element and the second electrode element are aligned in a short-side direction of the sealing plate, a first tab group of one of the positive and negative electrode plates in the first electrode body element and a second tab group of one of the positive and negative electrode plates in the second electrode body element are electrically connected to the current collecting member; In the current collecting member, a connection portion with the first tab group and a connection portion with the second tab group are Arranged in the short side direction of the sealing plate, the first tab group and the second tab group are each curved; a surface of the current collector opposite to a surface on which a connection portion with the first tab group and a connection portion with the second tab group are formed overlaps the insulating member; the electrolyte injection hole is disposed between a connection portion with the first tab group and a connection portion with the second tab group in a short-side direction of the sealing plate; Prismatic secondary battery.

2. The insulating member has an opening in a region facing the electrolyte injection hole. The prismatic secondary battery according to claim 1 .

3. The insulating member has a rib disposed around the opening and protruding from the insulating member toward the electrode body. The prismatic secondary battery according to claim 2 .

4. In a short-side direction of the sealing plate, the first tab group is bent so as to fall toward the second tab group, and the second tab group is bent so as to fall toward the first tab group. The prismatic secondary battery according to any one of claims 1 to 3.

5. An insulating sheet is interposed between the electrode body and the rectangular exterior body. The prismatic secondary battery according to any one of claims 1 to 4.

Images