Storage element

Abstract

A storage element (battery) (1) includes an electrode body (20) having a current collector tab (28, 29) formed of a plurality of protrusions (24b, 26b) protruding from a first straight portion (20c) on one side in the stacking direction of electrode sheets (21, 22), and the electrode body (20) is housed in a case (external body) (10). In addition, a current collector (60A, 60B) electrically connected to an external terminal (50A, 50B) arranged in the case (10) is provided, and the current collector (60A, 60B) is connected to the current collector tab (28, 29) arranged in the stacking direction of the electrode sheets (21, 22) on the side of the second straight portion (20d) where the protrusions (24b, 26b) are not provided.

Description

[0001] This application is a divisional application of an invention patent application with an application date of December 11, 2015, application number 201580072645.9, and invention name “Electrical Storage Element”. Technical Field

[0002] The present invention relates to an electric storage element including a non-electrolyte secondary battery such as a lithium ion secondary battery. Background Art

[0003] Patent document 1 discloses a storage element, which includes an electrode body, which is wound into an oblong shape in a plan view with a separator sandwiched between a positive electrode sheet and a negative electrode sheet. In the electrode body, a positive electrode collector tab and a negative electrode collector tab are provided at intervals on a first straight line portion of one side of a pair of opposing straight line portions. A separator is arranged above the collector tab, and above the separator, the collector tab is electrically connected to the collector.

[0004] The electric storage element of Patent Document 1 requires a large space for arranging the electric collector above the first straight portion where the electric collector tab of the electrode body is protruding. Therefore, when manufacturing an electric storage element of the same height, the electrode body must be made smaller, and the capacity of the electric storage element is reduced.

[0005] Prior Art Literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-70918 Summary of the invention

[0008] -Problems to be solved by the invention-

[0009] An object of the present invention is to achieve a higher capacity of an electric storage element.

[0010] -Methods for solving the problem-

[0011] The present invention provides a storage element, comprising: an electrode body, having positive electrode sheets and negative electrode sheets alternately stacked with separators sandwiched therebetween, and a positive collector terminal and a negative collector terminal composed of a plurality of protrusions protruding from a first portion on one side of the stacking direction of each electrode sheet, the electrode body being accommodated in a shell; a positive external terminal and a negative external terminal, arranged in the shell; and a positive collector and a negative collector, arranged between the electrode body and the shell, electrically connected to the external terminals, and respectively electrically connected to the collector terminals arranged in the stacking direction of each electrode sheet on a second portion side on the other side of the stacking direction of each electrode sheet.

[0012] In the storage element of the present invention, the collector connector protrudes from the first part side of the electrode body, and the connection portion between the collector connector and the collector body is located on the second part side where the collector connector does not protrude. Therefore, the height of the end of the electrode body can be reduced, and the distance between the electrode body and the shell can be reduced. Therefore, when manufacturing a storage element of the same height, the electrode body can be enlarged, so that a high capacity can be achieved.

[0013] -Effects of the Invention-

[0014] According to the electric storage device according to the present invention, the end portion of the electrode body can be reduced in height and the capacity of the electric storage device can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a longitudinal sectional view of the non-electrolyte secondary battery according to the first embodiment of the present invention.

[0016] Figure 2 yes Figure 1 An exploded perspective view of a non-electrolyte secondary battery.

[0017] Figure 3 It is a three-dimensional diagram of the electrode body.

[0018] Figure 4 This is an expanded view of the electrode body.

[0019] Figure 5 yes Figure 1 An enlarged view of part V.

[0020] Figure 6 yes Figure 1 An enlarged view of part VI.

[0021] Figure 7 It is a three-dimensional diagram of the electrode body and the current collector.

[0022] Figure 8 yes Figure 1 A partially broken perspective view of a non-electrolyte secondary battery.

[0023] Fig. 9 yes Figure 1 A partially exploded side view of a non-electrolyte secondary battery.

[0024] Fig.10 yes Figure 1 A cross-sectional view of a portion of a non-electrolyte secondary battery.

[0025] Fig.11A It is a cross-sectional view showing the assembly process of the current collecting tab.

[0026] Fig. 11B It is a cross-sectional view showing a state where the current collecting tab is assembled.

[0027] Fig.12 It is a top view of the electrode body and the current collector.

[0028] Fig.13A It is a top perspective view of the upper partition.

[0029] Fig. 13B It is a bottom perspective view of the upper partition.

[0030] Fig.14A It is a cross-sectional view showing the assembly process of the electrode body and the cover.

[0031] Fig. 14B It is a cross-sectional view showing another assembly step of the electrode body and the cover.

[0032] Fig.15 It is a partial cross-sectional view of the non-electrolyte secondary battery according to the second embodiment.

[0033] Fig.16 It is a partial cross-sectional view of a non-electrolyte secondary battery according to a third embodiment.

[0034] Fig.17 It is a plan view of the electrode body and the current collector according to the third embodiment.

[0035] Fig.18 This is a partial cross-sectional view showing a modified example of the non-electrolyte secondary battery.

[0036] -Explanation of symbols-

[0037] 1 Battery (storage element)

[0038] 10. Outer body (housing)

[0039] 11 Shell body

[0040] 11a Opening

[0041] 11b Bottom wall

[0042] 11c Long side wall

[0043] 11d Short side wall

[0044] 12 Cover

[0045] 12a Outer side

[0046] 12b Inside side

[0047] 20 Electrode body

[0048] 20a end

[0049] 20b End

[0050] 20c First straight line

[0051] 20d Second straight line

[0052] 20e Bend

[0053] 21. Positive electrode sheet

[0054] 22 Negative electrode sheet

[0055] 23 Bulkhead

[0056] 24. Positive metal foil

[0057] 24a Uncoated part

[0058] 24b Protrusion

[0059] 24b' First protrusion

[0060] 24b” Second protrusion

[0061] 25 Positive electrode active material layer

[0062] 26 Negative electrode metal foil

[0063] 26a Uncoated part

[0064] 26b Protrusion

[0065] 26b' First protrusion

[0066] 26b” Second protrusion

[0067] 27 Negative electrode active material layer

[0068] 28 Positive electrode collector connector

[0069] 28a Joint

[0070] 28b Non-joined part

[0071] 28c 1st bending part

[0072] 28d Second bending part

[0073] 29 Negative collector connector

[0074] 29a Joint

[0075] 29b Non-joined part

[0076] 29c 1st bending part

[0077] 29d Second bending part

[0078] 30 Insulation sheet

[0079] 40 Bottom spacer

[0080] 50A, 50B external terminals

[0081] 51A, 51B Plate-shaped part

[0082] 52 Shaft

[0083] 52a Expanded diameter

[0084] 53 Rivet

[0085] 53a Jaw

[0086] 53b Expanded diameter

[0087] 60A, 60B current collector

[0088] 61A, 61B Welded portion (joined portion)

[0089] 61a Lower surface

[0090] 61b Upper surface

[0091] 62A, 62B Fastened portion

[0092] 63A, 63B Edge

[0093] 64A, 64B Step

[0094] 65A, 65B through hole

[0095] 66A, 66B Avoidance Section

[0096] 70A, 70B upper seal

[0097] 80A, 80B lower seal

[0098] 90 Upper spacer

[0099] 91 Central

[0100] 91a Opening

[0101] 92A, 92B Current collector housing

[0102] 93A, 93B Side wall

[0103] 94A, 94B Upper wall

[0104] 94a Front End

[0105] 95A, 95B Lower wall

[0106] 95a Front End

[0107] 96A, 96B Insertion slot

[0108] 97A, 97B Fastened portion arrangement portion

[0109] 97a Bottom wall

[0110] 97b Inner peripheral wall portion

[0111] 97c Outer peripheral wall portion

[0112] 98A, 98B opening

[0113] A Winding shaft

[0114] B Centerline

[0115] C1, C2 bending positions. DETAILED DESCRIPTION

[0116] Hereinafter, the embodiments of the present invention will be described with reference to the attached drawings. In addition, in the following description, terms indicating specific directions or positions (for example, terms including "upper", "lower", "side", and "end") are used as needed, but the use of these terms is to facilitate the understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. In addition, the following description is essentially only an example and is not intended to limit the present invention, its application or its use.

[0117] (First embodiment)

[0118] Figure 1 as well as Figure 2 A lithium ion secondary battery (hereinafter simply referred to as a battery) 1 according to a first embodiment of the present invention is shown.

[0119] (Overall composition)

[0120] Reference Figure 1 as well as Figure 2 The battery 1 includes: an outer casing 10, an electrode body 20, an insulating sheet 30, a bottom separator 40, positive and negative external terminals 50A, 50B, positive and negative current collectors 60A, 60B, upper seals 70A, 70B, lower seals 80A, 80B, and an upper separator 90.

[0121] The outer body (shell) 10 includes: a shell body 11, and a cover 12 that closes the opening 11a of the shell body 11. In the present embodiment, the shell body 11 and the cover 12 are made of aluminum or aluminum alloy. The shell body 11 includes: a bottom wall portion 11b in the shape of a rectangular plate, a pair of long side wall portions 11c, 11c rising from the long sides of the bottom wall portion 11b, and a pair of short side wall portions 11d, 11d rising from the short sides of the bottom wall portion 11b. The cover 12 is generally in the shape of a rectangular plate. The upper ends of the long side wall portion 11c and the short side wall portion 11d define the opening 11a of the shell body 11. The electrode body 20 is accommodated in the shell body 11 filled with an electrolyte. The electrode body 20 is covered with an insulating sheet 30. A bottom separator 40 is sandwiched between the electrode body 20 and the bottom wall portion 11b of the shell body 11. The lower seals 80A and 80B and the upper spacer 90 are also accommodated in the housing body 11 .

[0122] Refer to Figure 3 as well as Figure 4 The electrode body 20 is a component formed by overlapping and winding a positive electrode sheet 21, a negative electrode sheet 22, and two separators 23, 23 made of a microporous resin sheet, which are all long strips of a certain width, into a generally high-flattened oblong shape. Between a layer of the positive electrode sheet 21 and a layer of the negative electrode sheet 22 adjacent thereto, one of the two separators 23, 23 is sandwiched. The axis (winding axis) of winding the positive electrode sheet 21, the negative electrode sheet 22, and the two separators 23, 23 is at Figure 3 The winding axis A of the electrode body 20 is generally in the direction in which the bottom wall portion 11b and the opening 11a of the case body 11 are opposed to each other ( Figure 1 The rotatable housing 10 is in an extended posture (in the up-down direction) and is housed in the shell body 11.

[0123] like Figure 3 As shown, the end portions 20a, 20b of the electrode body 20 viewed in the extending direction of the winding axis A include a pair of straight portions 20c, 20d facing each other, and a pair of curved portions 20e, 20e facing each other to connect the straight portions 20c, 20d.

[0124] The positive electrode sheet 21 includes a strip-shaped positive electrode metal foil 24 and positive electrode active material layers 25 formed on both sides of the positive electrode metal foil 24. Figure 3 as well as Figure 4 The positive electrode active material layer 25 is provided at the end portion (lower side in the middle) extending to the side edge of the positive electrode metal foil 24. Figure 3 as well as Figure 4 At the end portion (the upper side in the center), the positive electrode active material layer 25 is not provided, but an uncoated portion 24a is provided to expose the positive electrode metal foil 24.

[0125] The negative electrode sheet 22 includes a strip-shaped negative electrode metal foil 26 and negative electrode active material layers 27 formed on both sides of the negative electrode metal foil 26. Figure 3 as well as Figure 4 The negative electrode active material layer 27 is provided at the end (lower side in the figure) of the negative electrode sheet 22 until the side of the negative electrode metal foil 26. Figure 3 as well as Figure 4 At the end portion (the upper side in the center), the negative electrode active material layer 27 is not provided, but an uncoated portion 26a is provided to expose the negative electrode metal foil 26.

[0126] The positive electrode metal foil 24 is provided with a plurality of protrusions 24b protruding outward in the width direction from the uncoated portion 24a at intervals in the long side direction. In a state where the positive electrode sheet 21, the negative electrode sheet 22, and the separators 23, 23 are overlapped and wound, a tab-shaped portion (positive electrode current collector tab 28) is formed in which the plurality of protrusions 24b overlap each other and protrude from the electrode body 20. The negative electrode metal foil 26 is also provided with a plurality of protrusions 26b similar to the protrusions 24b of the positive electrode metal foil 24, and these protrusions 26b overlap each other to form a negative electrode current collector tab 29 protruding from the electrode body 20.

[0127] Reference Figure 3 The positive electrode current collecting tab 28 and the negative electrode current collecting tab 29 are connected from one end 20a ( Figure 3 In addition, the positive electrode current collector tab 28 and the negative electrode current collector tab 29 protrude from one side (the upper end) of the pair of straight portions 20c and 20d relative to the center line B in the long-side direction when the end 20a of the electrode body 20 is viewed from the extending direction of the winding axis A. Figure 3 The first straight portion 20c (in the front side) protrudes.

[0128] On one end side of the cover 12 ( Figure 1 The positive external terminal 50A is configured on the other end side ( Figure 1 The external terminal 50B of the negative electrode is arranged on the right side in the middle. The external terminals 50A and 50B include plate-like parts 51A and 51B arranged on the outer side surface (upper side surface) 12a of the cover 12. A connecting member such as a bus bar is welded to the plate-like parts 51A and 51B to connect to the external circuit.

[0129] Reference Figure 1 as well as Figure 2 And refer to Figure 5The positive electrode external terminal 50A includes a plate-shaped portion 51A disposed on the outer side surface 12a of the cover 12, and a cylindrical shaft portion 52 protruding downward from the lower surface of the plate-shaped portion 51A. The plate-shaped portion 51A and the shaft portion 52 are integrally formed. The shaft portion 52 penetrates the cover 12 and protrudes into the interior of the case body 11.

[0130] The expanded diameter portion 52a is provided at the lower end of the shaft portion 52 of the positive electrode external terminal 50A, whereby the positive electrode external terminal 50A is fastened and fixed to the cover 12. Specifically, the positive electrode external terminal 50A and the collector 60A are fixed to the cover 12 by sandwiching an upper seal 70A made of insulating resin, the cover 12, a lower seal 80A of insulating resin, and the positive electrode collector 60A (fastened portion 62A described later) between the plate-like portion 51A of the external terminal 50A and the expanded diameter portion 52a. The upper seal 70A is sandwiched between the outer side surface 12a of the cover 12 and the external terminal 50A, and the lower seal 80A is sandwiched between the inner side surface (lower side surface) 12b of the cover 12 and the collector 60A. In the present embodiment, the positive electrode external terminal 50A and the collector 60A are made of aluminum or an aluminum alloy.

[0131] Reference Figure 1 as well as Figure 2 And refer to Figure 6 The negative electrode external terminal 50B includes a plate-shaped portion 51B disposed on the outer side surface 12a of the cover 12, and a rivet 53 independent of the plate-shaped portion 51B. The jaw 53a at the upper end of the rivet 53 is pressed into a through hole formed in the plate-shaped portion 51B, thereby fixing the rivet 53 to the plate-shaped portion 51B. The rivet 53 protrudes downward from the lower surface of the plate-shaped portion 51B, penetrates the cover 12, and protrudes into the interior of the case body 11.

[0132] The expanded diameter portion 53b is provided at the lower end of the rivet 53 of the negative electrode external terminal 50B, thereby the negative electrode external terminal 50B is fastened and fixed to the cover 12. Specifically, the upper seal 70B made of insulating resin, the cover 12, the upper seal 70B made of insulating resin, and the negative electrode collector 60B are sandwiched between the plate-shaped portion 51B of the external terminal 50B and the expanded diameter portion 53b, so that the negative electrode external terminal 50B and the collector 60B are fixed to the cover 12. The lower seal 80B is sandwiched between the outer side surface 12a of the cover 12 and the external terminal 50B, and the lower seal 80B is sandwiched between the inner side surface 12b of the cover 12 and the negative electrode collector 60B. In the present embodiment, the plate-shaped portion 51B of the negative electrode external terminal 50B is made of aluminum or an aluminum alloy, the rivet 53 is made of copper or a copper alloy, and the negative electrode collector 60B is made of copper or a copper alloy.

[0133] like Figure 7As shown most clearly, the positive electrode current collector 60A includes a welded portion 61A and a fastened portion 62A. The welded portion 61A is welded to the positive electrode current collector tab 28 of the electrode body 20, and is electrically and mechanically connected. As described above, the fastened portion 62A is fastened and fixed to the cover 12 by the enlarged diameter portion 52a formed on the shaft portion 52 of the positive electrode external terminal 50A. Similarly, the negative electrode current collector 60B includes a welded portion 61B and a fastened portion 62B. The welded portion 61B is welded to the negative electrode current collector tab 29 of the electrode body 20, and is electrically and mechanically connected. As described above, the fastened portion 62B is fastened and fixed to the cover 12 by the enlarged diameter portion 53b of the rivet 53 formed on the negative electrode external terminal 50B.

[0134] like Figure 8 as well as Fig. 9 As shown most clearly, the upper separator 90 is sandwiched between the electrode body 20 and the inner side surface 12 b of the lid 12 .

[0135] (Details of collector connector)

[0136] like Fig.10 As shown most clearly, the collector terminals 28 and 29 are located at a straight line portion (first portion) 20c on one side of a pair of straight line portions 20c and 20d in which the electrode sheets 21 and 22 are stacked by winding, and the base side is bent toward the straight line portion (second portion) 20d on the other side, and the front end side is electrically connected to the collectors 60A and 60B arranged in the stacking direction of the electrode sheets 21 and 22 on the straight line portion 20d side.

[0137] Reference Fig.10 And refer to Fig.11A , B, the current collecting tabs 28, 29 include: a front end side joint portion 28a, 29a where the protrusions 24b, 26b are joined to each other by welding, and a base side non-joined portion 28b, 29b which is not joined to each other. The joint portions 28a, 29a are bent so that the protrusions 24b, 26b are bent integrally. The non-joined portions 28b, 29b are bent so that the protrusions 24b, 26b can be freely bent at different curvatures.

[0138] The total length L of the current collector tabs 28 and 29 is set to a size that can be folded twice between the electrode body 20 and the cover 12. The first bent portions 28c and 29c are located on the side of the stacked electrode sheets 21 and 22, and are bent from the first straight portion 20c side to the second straight portion 20d side. The second bent portions 28d and 29d are located closer to the current collectors 60A and 60B than the first bent portions 28c and 29c, and are bent from the second straight portion 20d side to the first straight portion 20c side. The second bent portions 28d and 29d are located near the connecting portion of the current collectors 60A and 60B, that is, the second welded portions 61A and 61B. Although these bent portions 28c, 29c, 28d, and 29d are set as the first and second from the base side of the current collector tabs 28 and 29, this is not intended to indicate the order of bending.

[0139] In addition, the total length L of the current collector tabs 28 and 29 is set to a size that allows the first and second bent portions 28c, 29c, 28d, and 29d to have a predetermined flexibility (gap). Specifically, the dimension L2 from the first bent portion 28c and 29c to the second bent portion 28d and 29d is longer than the dimension (distance) L1 from the first bent portion 28c and 29c to the base side end portion of the current collector tabs 28 and 29 in the second welded portion 61A and 61B. The dimension difference L3 between L1 and L2 is set to a length that does not interfere with the second bent portion 28d and 29d of the connecting portion 95A and 95B of the upper spacer 90.

[0140] The non-joined portions 28b and 29b of the collector tabs 28 and 29 are set such that the total length of the outer protrusions 24b and 26b gradually increases with respect to the first protrusions 24b' and 26b' located in the center of the stacking direction. Specifically, the collector tabs 28 and 29 are formed into a line-symmetrical shape with respect to the first protrusions 24b' and 26b' located in the center of the stacking direction of the electrode sheets 21 and 22 of the first straight portion 20c. Fig.11A As shown most clearly in FIG. 1 , the first protrusions 24b' and 26b' are arranged to extend on one side relative to the continuous electrode sheets 21 and 22, and the protrusion dimension from the end 20a is set to the total length L. The other protrusions 24b and 26b are arranged obliquely from the electrode sheets 21 and 22 toward the front ends of the first protrusions 24b' and 26b', and are set to have the same dimensions as the front ends. Fig. 11BAs shown, the joints 28a and 29a are formed by welding the front ends of all the protrusions 24b and 26b. Thus, the protrusions 24b and 26b forming the non-joining portions 28b and 29b of the first bent portions 28c and 29c are provided with different optimal gaps. In addition, the number of the protrusions 24b and 26b is not limited to an odd number, and can be an even number. In the case of an even number, a line-symmetrical shape is formed with a pair of first protrusions 24b' and 26b' located in the center of the stacking direction as a reference.

[0141] (Details of current collector)

[0142] Reference Fig.10 And refer to Figure 7 as well as Fig.12 The current collectors 60A and 60B electrically connect the current collector tabs 28 and 29 to the external terminals 50A and 50B of the cover 12. The current collectors 60A and 60B have escape portions 66A and 66B for avoiding interference with the first bent portions 28c and 29c of the current collector tabs 28 and 29 in addition to the welded portions 61A and 61B as the joined portions and the fastened portions 62A and 62B as the connecting portions.

[0143] like Fig.12 As shown most clearly, the edges 63A and 63B of the welded portions 61A and 61B and the fastened portions 62A and 62B of the current collectors 60A and 60B are located on a straight line. The welded portions 61A and 61B and the fastened portions 62A and 62B are each rectangular in a plan view. The width H1 of the welded portions 61A and 61B in the direction in which the current collector tabs 28 and 29 protrude is narrower than the width H2 of the fastened portions 62A and 62B. The fastened portions 62A and 62B and the welded portions 61A and 61B are arranged in a direction intersecting with the direction in which the current collector tabs 28 and 29 protrude ( Figure 3 adjacent to the outside of the center line B).

[0144] like Figure 7 As shown most clearly, between the welded portions 61A, 61B and the fastened portions 62A, 62B, step portions 64A, 64B are provided for arranging the fastened portions 62A, 62B on the upper side of the upper spacer 90. The collector tabs 28, 29 are welded to the welded portions 61A, 61B on the side opposite to the protruding direction of the step portions 64A, 64B, i.e., the lower surface 61a side. The fastened portions 62A, 62B are provided with through holes 65A, 65B through which the shaft portions 52 of the external terminals 50A, 50B and the rivets 53 pass.

[0145] like Fig.12As shown most clearly, due to the difference in width H1, H2 of the welded portions 61A, 61B and the fastened portions 62A, 62B, the spaces adjacent to each other in the direction in which the collector tabs 28, 29 of the welded portions 61A, 61B protrude are the escape portions 66A, 66B. The width H2 of the fastened portions 62A, 62B is wider than the width in the stacking direction of the straight portions 20c, 20d of the electrode body 20. The fastened portions 62A, 62B are located at the end portion 20a of the electrode body 20, straddling the first and second straight portions 20c, 20d. The escape portions 66A, 66B are provided in the portion above the first straight portion 20c of the welded portions 61A, 61B. That is, by providing a portion ( Fig.12 A cutout is provided at the front end (joining portion 28a, 29a side) in the direction in which the current collecting tabs 28, 29 protrude, thereby forming escape portions 66A, 66B.

[0146] (the details of the upper spacer)

[0147] Reference Fig.10 And refer to Fig. 9 as well as Fig.13A , B, the upper separator 90 as a whole is in the same elongated rectangular shape as the cover 12, and includes: a central portion 91, and a pair of current collector housing portions 92A, 92B extending from the central portion. One end of the current collector housing portions 92A, 92B is connected to the central portion 91, and the other end is connected to the fastened portion arrangement portions 97A, 97B located on the bent portions 20e, 20e of the electrode body 20. An opening 91a is provided in the central portion 91 to face the safety valve provided in the cover 12.

[0148] The current collector housing 92A, 92B includes side walls 93A, 93B, upper walls 94A, 94B extending from the upper ends of the side walls 93A, 93B, and lower walls 95A, 95B extending from the lower ends of the side walls 93A, 93B substantially parallel to the upper walls 94A, 94B. Between the upper walls 94A, 94B and the front ends 94a, 95a of the lower walls 95A, 95B, there are formed horizontally long openings 98A, 98B into which the front ends of the current collector tabs 28, 29 including the second bent portions 28d, 29d are inserted.

[0149] The side wall portions 93A and 93B are located on the second straight portion 20d side of the electrode body 20. The upper wall portions 94A and 94B extend from the second straight portion 20d side to the first straight portion 20c side between the welded portions 61A and 61B of the current collectors 60A and 60B and the inner side surface 12b of the cover 12. The front end 94a of the upper wall portions 94A and 94B is located near the escape portions 66A and 66B so as to cover the welded portions 61A and 61B of the current collectors 60A and 60B. The lower wall portions 95A and 95B extend from the second straight portion 20d side to the first straight portion 20c side between the end portion 20a of the electrode body 20 and the current collector tabs 28 and 29. The front end 95a of the lower wall portions 95A, 95B is located on the first straight portion 20c of the electrode body 20, between the second protrusions 24b", 26b" at the side ends of the second straight portion 20d and the first protrusions 24b', 26b' at the center. In other words, there are no lower wall portions 95A, 95B on the upper portion of the first straight portion 20c, and a space is formed in which the collector terminals 28, 29 can be arranged toward the openings 98A, 98B.

[0150] Reference Figure 8 as well as Fig.13A Insertion grooves 96A and 96B are provided at the side ends of the fastened portion placement portions 97A and 97B of the upper wall portions 94A and 94B. When the welded portions 61A and 61B of the current collectors 60A and 60B are placed in the current collector housing portions 92A and 92B, the step portions 64A and 64B of the current collectors 60A and 60B are located in the insertion grooves 96A and 96B. As a result, the fastened portions 62A and 62B of the current collectors 60A and 60B are located on the fastened portion placement portions 97A and 97B.

[0151] like Fig.13A As shown in FIG. 1 and FIG. 2, the fastened portion arrangement portion 97A, 97B includes a bottom wall portion 97a and an inner peripheral wall portion 97b formed on the bottom wall portion 97a. The enlarged diameter portions 52a, 53b of the external terminals 50A, 50B are located inside the inner peripheral wall portion 97b. On the bottom wall portion 97a, an outer peripheral wall portion 97c is further provided to arrange the fastened portions 62A, 62B of the current collectors 60A, 60B so as to surround the inner peripheral wall portion 97b.

[0152] Next, the assembly process of the battery 1 will be described.

[0153] like Figure 7 as well as Fig.12As shown, the electrode body 20 is arranged horizontally so that the first straight portion 20c side where the current collector tabs 28 and 29 protrude is located at the bottom. Next, the current collectors 60A and 60B are arranged so that the fastened portions 62A and 62B are located above the welded portions 61A and 61B, and the electrode body 20 is located on the side of the edges 63A and 63B of the welded portions 61A and 61B. Then, the welded portions 61A and 61B of the current collectors 60A and 60B are arranged on the upper surface of the front end of the current collector tabs 28 and 29, and the current collector tabs 28 and 29 are connected to the lower surface 61a side of the welded portions 61A and 61B by ultrasonic welding.

[0154] Next, if Fig.14A As shown, the electrode body 20 is arranged so that the first straight portion 20c that makes the collector tabs 28 and 29 protrude is located at the top. Next, the upper seals 70A, 70B and the external terminals 50A, 50B are installed on the outer side surface 12a of the cover 12, and the arrangement is made so that the inner side surface 12b is located at the top. Next, the lower seals 80A, 80B and the fastened portions 62A, 62B of the collectors 60A, 60B are arranged on the inner side surface 12b of the cover 12. Then, the shaft portions 52 and rivets 53 of the external terminals 50A, 50B are fastened to electrically connect the external terminals 50A, 50B to the collectors 60A, 60B. As a result, the electrode body 20 is electrically connected to the external terminals 50A, 50B via the collector tabs 28, 29 and the collectors 60A, 60B.

[0155] If the cover 12 is assembled to the electrode body 20, then, Fig. 11B as well as Fig.14A As shown in FIG. 1 , the current collector tabs 28 and 29 are bent 180 degrees around the bend position C1 near the welded portions 61A and 61B of the current collectors 60A and 60B. The bending direction of the current collector tabs 28 and 29 is opposite to the second straight portion 20d so that the cover 12 is located on the upper side in the assembled state. Next, as shown in FIG. Fig. 11B as well as Fig. 14B As shown by the middle arrow, the current collecting tabs 28 and 29 are bent 90 degrees around the bending position C2 on the base side. The current collecting tabs 28 and 29 are bent toward the second straight portion 20d so that the cover 12 is located on the upper side in the assembled state.

[0156] Therefore, if Fig. 9As shown, the cover 12 is arranged parallel to the end 20a of the electrode body 20. In this state, the first bent portions 28c, 29c of the collector tabs 28, 29 are located on the first straight portion 20c, and the top of the protruding upper side passes through the escape portions 66A, 66B and is located above the lower surface 61a of the collectors 60A, 60B. In other words, the top of the first bent portion 28c, 29c is located between the lower surface (opposing surface) 61a of the collectors 60A, 60B facing the electrode body 20 and the cover 12 of the outer body 10. The second bent portions 28d, 29d of the collector tabs 28, 29 are located on the second straight portion 20d, and the welded portions 61A, 61B that join the collector tabs 28, 29 are also located on the second straight portion 20d.

[0157] Next, the upper separator 90 is arranged in the lateral direction of the second straight portion 20d of the electrode body 20 and inserted between the electrode body 20 and the cover 12 from the lateral direction. Specifically, the upper separator 90 is arranged so that the front ends 94a and 95a of the current collector housing portions 92A and 92B face the electrode body 20. Next, as shown in FIG. Figure 8 as well as Fig.10 As shown, the upper wall portions 94A and 94B are inserted between the welded portions 61A and 61B and the inner side surface 12b of the cover 12, and the lower wall portions 95A and 95B are inserted between the current collector tabs 28 and 29 and the end portion 20a of the electrode body 20. Thus, the joint portion including the welded portions 61A and 61B and the second bent portions 28d and 29d of the current collectors 60A and 60B is arranged in the current collector housing portions 92A and 92B.

[0158] Next, if Figure 1 as well as Fig.10 As shown, after the outer periphery of the electrode body 20 and the upper separator 90 is covered by the insulating sheet 30, the electrode body 20 and the insulating sheet 30 are housed inside the case body 11. Finally, the cover 12 is pressed toward the case body 11, and the cover 12 is welded to the opening 11a of the case body 11 to seal.

[0159] At the end 20a side of the electrode body 20 of the battery 1 assembled in this way, the base (non-joining portion 28b, 29b) side of the current collector tabs 28, 29 is located at the first straight portion 20c side of the electrode body 20, and the front end (joining portion 28a, 29a) side of the current collector tabs 28, 29 is located at the second straight portion 20d side. As a result, the first bent portions 28c, 29c of the current collector tabs 28, 29 are located at the first straight portion 20c side, and the welded portions 61A, 61B of the current collectors 60A, 60B joined to the current collector tabs 28, 29 are located at the second straight portion 20d side. That is, the portion where the first bent portions 28c, 29c protruding by providing a gap are arranged and the portion where the enlarged joining portions 28a, 29a are arranged are arranged adjacent to each other in the lateral direction at the end 20a of the electrode body 20. Therefore, the end 20a of the electrode body 20 can be made shorter, and the distance between the electrode body 20 and the lid 12 can be reduced. Therefore, when manufacturing batteries 1 of the same height, the electrode body 20 can be made larger, thereby achieving higher capacity.

[0160] In addition, since the collector tabs 28 and 29 are formed to have a total length L that can be folded twice at the end 20a of the electrode body 20, the workability when connecting the collectors 60A and 60B connected to the collector tabs 28 and 29 to the external terminals 50A and 50B can be improved. In detail, when the shaft 52 and the rivet 53 of the external terminals 50A and 50B are fastened, it is possible to simply configure so that the fastening device does not contact the electrode body 20. Further, since the collector tabs 28 and 29 are the total length L in which the second bent portions 28d and 29d are arranged near the welded portions 61A and 61B of the collectors 60A and 60B, the assembly of the collectors 60A and 60B and the external terminals 50A and 50B is improved, and is set as short as possible. Therefore, the resistance when energized can be reduced as much as possible.

[0161] In addition, since the dimension L2 from the first bent portion 28c, 29c to the second bent portion 28d, 29d is longer than the dimension L1 from the first bent portion 28c, 29c of the current collector tabs 28, 29 to the welded portion 61A, 61B of the current collector 60A, 60B, the current collector tabs 28, 29 themselves, the first bent portions 28c, 29c, and the second bent portions 28d, 29d can be made flexible. Therefore, the vibration and impact applied to the current collector tabs 28, 29 can be reduced during assembly and during driving after being mounted on the vehicle. Therefore, the current collector tabs 28, 29 can be prevented from being stretched or broken.

[0162] Furthermore, in the first bent portions 28c and 29c of the collector tabs 28 and 29, the full length of the outer protrusions 24b and 26b is gradually lengthened with reference to the first protrusions 24b' and 26b' in the center of the stacking direction. Furthermore, the first bent portions 28c and 29c are obtained by bending the non-joined portions 28b and 29b of the collector tabs 28 and 29. Therefore, different optimal gaps can be independently set for each protrusion 24b and 26b. Therefore, the extension and fracture of each protrusion 24b and 26b can be reliably prevented.

[0163] (Second embodiment)

[0164] Fig.15 The battery 1 of the second embodiment is shown. In the second embodiment, the second bent portion 28d, 29d is bent at the lower part of the welded portion 61A, 61B of the collector 60A, 60B, which is different from the first embodiment. In the second embodiment, the same action and effect as the first embodiment can be obtained, and the total length of the collector tabs 28, 29 can be shortened as much as possible, so that the resistance when the power is turned on can be reduced. In addition, since the collector tabs 28, 29 connected to the collectors 60A, 60B do not contact the outer body 10, as shown in the figure, the upper separator 90 may not be arranged in the outer body 10. Alternatively, the upper separator 90 of the side wall portions 93A, 93B without the collector housing 92A, 92B can be used. Therefore, since the number of components can be reduced or the structure of the upper separator 90 can be simplified, cost reduction can be achieved.

[0165] (Third embodiment)

[0166] Fig.16 The third embodiment shows a battery 1. The third embodiment is different from the first embodiment in that the current collector tabs 28 and 29 are joined to the upper surfaces 61b of the welded portions 61A and 61B of the current collectors 60A and 60B, and the sides 63A and 63B of the welded portions 61A and 61B are used to bend the second bent portions 28d and 29d.

[0167] like Fig.17As shown, when the current collectors 60A and 60B are assembled to the current collector tabs 28 and 29, similarly to the first embodiment, the electrode body 20 is arranged horizontally so that the first straight portion 20c side is located at the bottom, and the current collectors 60A and 60B are arranged so that the fastened portions 62A and 62B are located above the welded portions 61A and 61B. In addition, the electrode body 20 is arranged on the sides 63A and 63B of the welded portions 61A and 61B, and the current collector tabs 28 and 29 are arranged on the upper surface 61b side of the welded portions 61A and 61B of the current collectors 60A and 60B. And, the current collector tabs 28 and 29 are connected to the upper surface 61b side of the welded portions 61A and 61B by ultrasonic welding.

[0168] Next, similarly to the first embodiment, the collectors 60A, 60B connected to the collector tabs 28, 29 are arranged on the inner side surface 12b of the cover 12 provided with the upper seals 70A, 70B, the external terminals 50A, 50B and the lower seals 80A, 80B, and the collectors 60A, 60B are connected to the external terminals 50A, 50B by fastening.

[0169] Next, when the current collector tabs 28 and 29 are bent and the cover 12 is placed on the end 20a of the electrode body 20, first, the current collector tabs 28 and 29 are bent so as to be wound around the sides 63A and 63B of the current collectors 60A and 60B to form the second bent portions 28d and 29d. Next, the current collector tabs 28 and 29 are bent 90 degrees on the base side and the cover 12 is placed on the end 20a of the electrode body 20.

[0170] Then, similarly to the first embodiment, after the upper spacer 90 is disposed between the electrode body 20 and the lid 12 , the insulating sheet 30 is disposed on the outer periphery. Next, the electrode body 20 is disposed inside the case body 11 , and the opening 11 a of the case body 11 is sealed by the lid 12 .

[0171] In such a third embodiment, the same action and effect as in the first embodiment can be obtained. Furthermore, since the second bent portions 28d and 29d can be formed to be wound around the current collectors 60A and 60B, the workability can be improved. In addition, as in the second embodiment, the total length of the current collector tabs 28 and 29 can be shortened as much as possible. In addition, since the current collector tabs 28 and 29 do not contact the outer casing 10, it is also possible to configure the outer casing 10 without configuring the upper spacer 90, or without configuring the side wall portions 93A and 93B of the current collector housing portions 92A and 92B.

[0172] In addition, the battery 1 of the present invention is not limited to the above-mentioned embodiment, and various modifications can be made.

[0173] For example, although the current collecting tabs 28 and 29 can be bent twice between the electrode body 20 and the lid 12, they can also be bent as follows. Fig.18 As shown, only one bend (first bend portion 28c, 29c) is made. Alternatively, the bend may be made three or more times. That is, in the current collectors 60A and 60B, as long as the first bend portion 28c and 29c are arranged on the first straight portion 20c side where the current collector tabs 28 and 29 protrude, and the welded portions 61A and 61B of the current collectors 60A and 60B are arranged on the second straight portion 20d side where the current collector tabs 28 and 29 do not protrude, the number of bends of the current collector tabs 28 and 29 can be changed as desired.

[0174] In addition, although the current collector tabs 28 and 29 are set so that the total length of the protrusions 24b and 26b located on the outside gradually increases, it is also possible to set the total length of all protrusions 24b and 26b to be the same. In addition, although the protrusions 24b and 26b are welded to form the joints 28a and 29a and the non-joints 28b and 29b, it is also possible not to form the joints 28a and 29a in advance.

[0175] In addition, although the electrode body 20 is housed in the case body 11 so that the current collecting tabs 28 and 29 are located on the opening 11a side, it can also be housed in the case body 11 so that the current collecting tabs 28 and 29 are located on the one short side wall portion 11d side. In this case, the external terminals 50A and 50B can also be arranged in the case body 11.

[0176] In addition, the present invention is not limited to a wound electrode body 20 in which a strip-shaped positive electrode sheet 21, a negative electrode sheet 22 and a separator 23 are wound around a winding axis A, but can also be applied to a stacked electrode body in which rectangular positive electrode sheets, negative electrode sheets and separators are stacked in one direction.

[0177] Furthermore, the present invention is not limited to secondary batteries such as non-electrolyte secondary batteries including lithium ion batteries, and can also be applied to various power storage elements including primary batteries and capacitors.

Claims

1. A power storage element comprising: An electrode body having electrode sheets stacked with separators therebetween and a current collector tab consisting of a plurality of protrusions protruding from a first portion on one side of the stacking direction of the electrode sheets, the electrode body being accommodated in a case; An external terminal is disposed on the housing; and a current collector disposed between the electrode body and the case, electrically connected to the external terminal, and electrically connected to the current collector tab on the second portion side on the other side of the stacking direction of the electrode sheet, The housing includes a housing body and a cover for closing an opening of the housing body. The current collecting tab has a first bent portion bent from the first portion side to the second portion side, The top portion of the first bent portion that protrudes toward the current collector is located between a surface of the electrode body that faces the current collector and the lid of the case.

2. The electric storage element according to claim 1, wherein The electrode body is wound around a winding axis by overlapping the separator between the electrode sheets, and the end portion observed from the direction in which the winding axis extends is an oblong shape having a pair of straight portions facing each other and a pair of curved portions facing each other so as to connect the straight portions. The current collecting tab is disposed on a first straight portion, which is one side of the first portion, of the pair of straight portions, and the current collecting tab is connected to the current collector on a second straight portion, which is the other side of the second portion.

3. The electric storage element according to claim 1 or 2, wherein: The current collecting tab has two or more bent portions, and the two or more bent portions include the first bent portion located on the electrode sheet side and the second bent portion located on the current collector side and bent from the second portion side toward the first portion side.

4. The electric storage element according to claim 3, wherein The second bent portion of the collector joint is arranged between the collector and the shell, and the dimension from the first bent portion of the collector joint to the second bent portion is set to be longer than the dimension from the first bent portion of the collector joint to the connection portion between the collector joint and the collector.

5. The electric storage element according to claim 4, wherein The current collecting tabs are joined to each other in a state where the other protrusions are arranged with the first protrusion located at the center of the stacking direction of the electrode sheets as a reference and the other protrusions are inclined toward the tip of the first protrusion.

6. The electric storage element according to claim 1 or 2, wherein: The current collector is provided with a relief portion where the top portion of the first bent portion is arranged.

7. The electric storage element according to claim 6, wherein The current collector further comprises: a joined portion joined to the current collecting tab; and a connecting portion connected to the external terminal and disposed adjacent to the joined portion in a direction intersecting the stacking direction. In the stacking direction, the width of the joined portion is narrower than the width of the connecting portion, The escape portion is formed by a space formed by the joined portions being adjacent to each other in the stacking direction.

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