Battery

Abstract

To appropriately join a non-coating part of a collector and a collector terminal.SOLUTION: A battery comprises: an electrode body that comprises a plurality of sheet-like collectors and electrode mixture layers each provided in each of the collectors, and includes non-coating parts in each of which each collector is exposed; and collector terminals 21 each joined to each of end parts of the electrode body in which the non-coating parts are laminated. The collector terminal 21 includes: a support part 22 including an opening 26 allowing a part of the end part of the electrode body to project; and a movable part 25 that includes a base end 29 coupled to the support part 22 and a free edge 30 positioned on a side opposite to the base end 29, and that is configured to be moved, when applied with an external force, from an initial position to a penetration insertion position in the open part 26, to contact the end part of the electrode body. There is formed a first groove part 31 to be inserted with the non-coating, between the movable part 25 at the penetration insertion position and the support part 22.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a battery having a current collecting structure. [Background technology]

[0002] Batteries such as lithium-ion secondary batteries and nickel-metal hydride secondary batteries include an electrode body that generates a battery reaction and a current collecting structure that electrically connects the electrode body and an external terminal. The electrode body is formed by winding or stacking a positive electrode sheet and a negative electrode sheet with a separator interposed therebetween. The electrode body has an uncoated portion at its end where the positive electrode composite or negative electrode composite is not coated and the current collector is exposed. The uncoated portion is formed by winding or stacking the positive electrode sheet and the negative electrode sheet, resulting in a stacked state at the end of the electrode body. A current collecting terminal, which is part of the current collecting structure, is joined to the uncoated portion by welding, ultrasonic welding, or the like.

[0003] Some current collecting terminals (electrode terminals) have grooves (slits) that allow uncoated portions to protrude (see, for example, Patent Document 1). The stacked uncoated portions are divided into several bundles (protruding ends). Each bundle of uncoated portions is inserted into a groove. Then, the bundle of uncoated portions protruding from the groove and the current collecting terminal are welded together to electrically connect the electrode body and the current collecting terminal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4918997 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the uncoated portion is metal foil and therefore easily bent. As shown in Fig. 12, when the uncoated portion 110 of the current collector 102 is inserted into the groove 101 of the current collecting terminal 100, the uncoated portion 110 may come into contact with the back surface 103 of the current collecting terminal 100 and bend. The bent uncoated portion 110 does not protrude from the groove 101. Because the uncoated portion 110 and the current collecting terminal 100 are welded from the front surface 105 of the current collecting terminal 100, if the uncoated portion 110 does not protrude from the groove 101, the uncoated portion 110 and the current collecting terminal 100 may not be properly joined. [Means for solving the problem]

[0006] A battery that solves the above problem comprises a plurality of sheet-like current collectors and an electrode composite layer provided on the current collectors, an electrode body having uncoated portions where the current collectors are exposed, and a current collecting terminal joined to the end of the electrode body where the uncoated portions are stacked, the current collecting terminal having a support portion with an opening that allows a portion of the end of the electrode body to protrude, a base end connected to the support portion and a free end located opposite the base end, and a movable portion that moves from an initial position to an insertion position where it contacts the end of the electrode body when an external force is applied, and a groove portion that penetrates the uncoated portion is formed between the movable portion and the support portion at the insertion position.

[0007] According to the above configuration, the uncoated portion protruding from the opening can be inserted into the groove by moving the movable portion of the current collector terminal from the initial position to the insertion position. As the movable portion moves, the groove gradually penetrates the uncoated portion from its end. As a result, deformation such as bending of the uncoated portion can be suppressed. This makes it possible to properly join the uncoated portion and the current collector terminal.

[0008] In a battery that solves the above problem, it is preferable that the portion of the groove through which the uncoated portion is inserted has different widths, and the width on the base end side is greater than the width of the end portion on the free end side. According to the above configuration, the width of the base end portion of the groove where the uncoated portion begins to be inserted is greater than the width of the free end portion, so that even if the uncoated portion and the first groove portion are slightly misaligned in the width direction, the uncoated portion can be guided into the first groove portion.

[0009] In a battery that solves the above problem, it is preferable that the groove formed between the support portion and the movable portion is a first groove portion, and the movable portion has a second groove portion that is a groove portion extending in the axial direction.

[0010] According to the above configuration, since the movable part also has a groove, the current collecting terminal and the electrode body can be joined with the uncoated part divided into even finer bundles. Furthermore, the second groove formed in the movable part has a larger width at the base end than at the free end, making it easier to insert the uncoated part into the second groove.

[0011] In a battery that solves the above problem, it is preferable that the portion of the second groove portion through which the uncoated portion is inserted has different widths, and the width on the base end side is greater than the width of the end portion on the free end side. According to the above configuration, the width of the base end portion of the second groove portion, where the uncoated portion begins to be inserted, is greater than the width of the free end portion thereof, so that the uncoated portion can be guided into the second groove portion even if the positions of the uncoated portion and the second groove portion are slightly misaligned in the width direction.

[0012] In the battery that solves the above problems, the support portion preferably has a frame portion that surrounds the opening. According to the above configuration, the opening is surrounded by the frame portion, so that the support portion can maintain a suitable strength.

[0013] In the battery that solves the above problems, it is preferable that the opening has a wide portion whose width is increased, and the frame portion extends along the shape of the opening. According to the above configuration, the frame surrounding the opening extends along the shape of the opening having the wide portion, so that when the current collecting terminal and the electrode body are joined by welding, heat loss from the frame is suppressed. This allows heat to be concentrated at the contact point between the current collecting terminal and the frame. This makes it possible to suppress welding defects between the current collecting terminal and the electrode body. [Effects of the Invention]

[0014] According to the present invention, bending of the uncoated portion of the current collector can be suppressed, thereby enabling the uncoated portion of the current collector and the current collecting terminal to be appropriately joined. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing a cross-sectional structure of a battery according to an embodiment of the present invention; [Figure 2] 3A and 3B are diagrams showing the structure of an electrode body in the same embodiment. [Figure 3] FIG. 2 is a perspective view of a current collecting terminal in the same embodiment. [Figure 4] FIG. 2 is a front view of the current collecting terminal in the embodiment. [Figure 5] 4 is a diagram showing a state in which a current collecting terminal is attached to the electrode body of the same embodiment. FIG. [Figure 6] FIG. 4 is an end view showing a state in which a current collecting terminal is attached to the electrode body of the embodiment. [Figure 7] 4 is a diagram showing a state in which a current collecting terminal is attached to the electrode body of the same embodiment. FIG. [Figure 8] FIG. 4 is an end view showing a state in which a current collecting terminal is attached to the electrode body of the embodiment. [Figure 9] FIG. 4 is an end view showing a state in which a current collecting terminal is joined to the electrode body of the embodiment. [Figure 10] FIG. 10 is a front view of a current collecting terminal according to another embodiment. [Figure 11] FIG. 10 is a front view of a current collecting terminal according to another embodiment. [Figure 12] FIG. 1 is an end view of a current collecting terminal according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0016] One embodiment of a battery will be described with reference to Figures 1 to 9. For example, a plurality of batteries are combined to form a battery pack. The battery pack is mounted on a vehicle such as an electric vehicle or a hybrid vehicle. In this embodiment, the battery will be described as a lithium ion secondary battery.

[0017] <Overall battery configuration> As shown in FIG. 1, the battery 1 includes a rectangular parallelepiped case 2 with an opening on the top side, a lid 3 that seals the case 2, and an electrode assembly 5 housed inside the case 2. The battery 1 forms a sealed battery container by attaching the lid 3 to the case 2. A non-aqueous electrolyte is housed inside the case 2. The battery 1 also includes a positive electrode external terminal 6P and a negative electrode external terminal 6N on the lid 3.

[0018] The electrode body 5 has an electrode body end portion 7P at one end and an electrode body end portion 7N at the other end. The electrode body end portion 7P is electrically connected to a current collecting terminal 21P. The current collecting terminal 21P is connected to an external terminal 6P via a connecting member 8P or the like. The electrode body end portion 7N is electrically connected to a current collecting terminal 21N. The current collecting terminal 21N is connected to an external terminal 6N via a connecting member 8N or the like. When the positive electrode external terminal 6P and the negative electrode external terminal 6N are described without distinction, they will be simply referred to as external terminals 6. When the current collecting terminals 21P, 21N are described without distinction, they will be simply referred to as current collecting terminals 21. When the electrode body end portions 7P, 7N are described without distinction, they will be simply referred to as electrode body end portions 7.

[0019] The configuration of the electrode assembly 5 will be described with reference to Fig. 2. The electrode assembly 5 includes a positive electrode sheet 10, a negative electrode sheet 11, and a separator 12. The positive electrode sheet 10 includes a long sheet-like positive electrode current collector 13 and positive electrode composite layers 14 provided on both sides of the positive electrode current collector 13. One end of the positive electrode sheet 10 in the short direction is provided with an uncoated portion 15 (unformed portion) where the positive electrode composite layer 14 is not formed and the positive electrode current collector 13 is exposed. The positive electrode composite layer 14 is an electrode composite layer containing a positive electrode active material.

[0020] The negative electrode sheet 11 includes a long sheet-like negative electrode current collector 16 and negative electrode composite layers 17 provided on both sides of the negative electrode current collector 16. One end of the negative electrode sheet 11 in the short direction is provided with an uncoated portion 18 where the negative electrode composite layer 17 is not formed and the negative electrode current collector 16 is exposed. The negative electrode composite layer 17 is an electrode composite layer containing a negative electrode active material.

[0021] The separator 12 is provided between the positive electrode sheet 10 and the negative electrode sheet 11 and at a position that will be the outermost when wound. The electrode assembly 5 illustrated in FIG. 2 is formed by winding a laminate in which the positive electrode sheet 10, the negative electrode sheet 11, and the separator 12 are stacked. The laminate is formed so that the longitudinal directions of the positive electrode sheet 10, the negative electrode sheet 11, and the separator 12 are aligned, and the uncoated portion 15 of the positive electrode sheet 10 and the uncoated portion 18 of the negative electrode sheet 11 protrude from different ends. The electrode assembly 5 is also formed into a flat shape by being pressed from its periphery. In the wound electrode assembly 5, the uncoated portion 15 of the positive electrode sheet 10 is stacked to form the electrode assembly end portion 7P. The uncoated portion 18 of the negative electrode sheet 11 is stacked to form the electrode assembly end portion 7N.

[0022] The materials of the positive electrode sheet 10 will be described. The positive electrode current collector 13 is formed from a metal foil or a thin metal plate. The positive electrode current collector 13 is made of, for example, an aluminum material containing aluminum as a main component. The positive electrode composite layer 14 includes a positive electrode active material, a conductive material, a binder, etc. Known positive electrode active material, conductive material, and binder can be used. For example, the positive electrode active material can be a lithium composite metal oxide, etc. The conductive material can be carbon black, etc. The binder can be polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), etc.

[0023] The material of the negative electrode sheet 11 will be described. The negative electrode current collector 16 is formed from a metal foil or a thin metal plate. The negative electrode current collector 16 is made of, for example, a copper material whose main component is copper. It also contains a positive electrode active material, a conductive material, a binder, etc. Known positive electrode active materials, conductive materials, and binders can be used. The negative electrode active material can be a carbon material such as graphite, hard carbon, soft carbon, or carbon nanotubes.

[0024] The separator 12 is a sheet made of a resin such as a polyolefin resin. An insulating layer may be provided on the surface of the separator 12. The insulating layer may be made of an insulating inorganic filler, an insulating resin, or the like.

[0025] <Collector terminal> Next, the configuration of the current collecting terminal 21 will be described with reference to Figures 3 and 4. The current collecting terminal 21P joined to the electrode body end 7P on the positive electrode side is made mainly of aluminum. The current collecting terminal 21N joined to the electrode body end 7N on the negative electrode side is made mainly of copper. The current collecting terminals 21P, 21N may be made of any material as long as they can be joined to the current collectors 13, 16, respectively.

[0026] 3, the current collecting terminal 21 has a front surface 21A and a back surface 21B. The current collecting terminal 21 is attached to the electrode body 5 with the back surface 21B facing the electrode body end portion 7P or the electrode body end portion 7N. The current collecting terminal 21 also includes a support portion 22 and a movable portion 25.

[0027] The support portion 22 has an elongated shape and includes a flat portion 23 and a frame portion 24. The flat portion 23 is connected to the external terminal 6 side. The frame portion 24 has an opening 26 on its inner side. The opening 26 penetrates the current collecting terminal 21 in the thickness direction. Of the frame portion 24, side portions 24A, 24B extending in the longitudinal direction of the current collecting terminal 21 are bent at multiple positions. Specifically, the side portions 24A, 24B are bent so that the back surface 21B of the central portion 24C protrudes beyond the back surface 21B of the flat portion 23. In other words, when the current collecting terminal 21 is attached to the electrode assembly end portion 7, the central portion 24C protrudes toward the electrode assembly 5. The side portions 24A, 24B each have an inclined portion 24D, a central portion 24C, and an inclined portion 24E. The inclined portions 24D, 24E are provided on both sides of the central portion 24C. A bottom portion 24F is provided between the tips of the side portions 24A, 24B.

[0028] The movable part 25 is provided in a cantilevered state on the flat part 23. The movable part 25 has a base end 29 that is an end in the longitudinal direction (axial direction) and is connected to the support part 22. The movable part 25 also has a free end 30 located on the opposite side of the base end 29. Figure 3 shows the movable part 25 in its initial position. Figure 4 shows the movable part 25 in its insertion position. At the insertion position, the movable part 25 contacts at least the electrode body ends 7P, 7N. At the insertion position, the movable part 25 is preferably located within the opening 26. The movable part 25 moves from its initial position to the insertion position when an external force is applied.

[0029] In the initial position, the movable part 25 has a posture in which it protrudes outward from the opening 26. In the initial position, the movable part 25 is inclined so as to move away from the opening 26 from the base end 29 toward the free end 30. The movable part 25 is bent in the same manner as the side parts 24A, 24B of the frame part 24. In addition, a groove part 32 is formed in the movable part 25. This groove part 32 will be referred to as a second groove part 32 hereinafter.

[0030] 4, the opening 26, the first groove 31 formed between the opening 26 and the movable portion 25, and the second groove 32 provided in the movable portion 25 will be described. The opening 26 has a first opening 27 having a width W1 and a second opening 28 continuous with the first opening 27. The width of the second opening 28 gradually increases from the first opening 27 toward the flat portion 23. The second opening 28 corresponds to the wide portion in the claims.

[0031] A first groove portion 31 is formed between the movable portion 25 and the frame portion 24 at the insertion position. The first groove portion 31 has a width that varies in the longitudinal direction. The first groove portion 31 formed between the second opening 28 and the movable portion 25 is called a guide groove 35. The first groove portion 31 formed between the first opening 27 and the movable portion 25 is called a narrow groove 36. The width W2 of the guide groove 35 gradually increases from the narrow groove 36 toward the flat portion 23. The first groove portion 31 located in the central portion 24C of the frame portion 24 is part of the guide groove 35 and part of the narrow groove 36.

[0032] The second groove portion 32 is composed of a guide groove 37 whose width W3 gradually increases and a narrow groove 38 whose width is constant. When the first groove portion 31 and the second groove portion 32 are not distinguished from each other, they will be simply referred to as groove portion 33. At the insertion position, the surface 21A of the movable portion 25 and the surface 21A of the frame portion 24 are flush (flat). The movable portion 25 has a central portion 25C that is flush with the central portion 24C of the frame portion 24. The second groove portion 32 located at the central portion 25C is part of the guide groove 37 and part of the narrow groove 38.

[0033] The uncoated portions 15, 18 are inserted through the central portion 24C of the frame portion 24 and the central portion 25C of the movable portion 25. That is, the portions of the first groove portion 31 through which the uncoated portions 15, 18 are inserted have different widths, with the width on the base end 29 side being larger than the width of the end portion on the free end 30 side. Also, the portions of the second groove portion 32 through which the uncoated portions 15, 18 are inserted have different widths, with the width on the base end 29 side being larger than the width of the end portion on the free end 30 side.

[0034] Furthermore, side portions 24A, 24B of frame portion 24 extend along the shape of opening 26. Side portions 24A, 24B have a constant width. That is, a pair of inclined portions 24D that define second opening 28 extend obliquely relative to the longitudinal direction such that the distance between each inclined portion 24D decreases from flat portion 23 toward central portion 24C when viewed from surface 21A.

[0035] <effect> Next, the function of the current collecting terminal 21 will be described with reference to Figures 5 to 8. Here, the case where the current collecting terminal 21N is attached to the electrode body end portion 7N will be described. Figures 5 and 7 show a simplified end face of the electrode body end portion 7N. The current collecting terminal 21 is attached by a worker.

[0036] 5, the current collecting terminal 21N is attached to the electrode body end 7N with the flat portion 23 facing the external terminal 6N. The flat portion 23 of the current collecting terminal 21N is abutted against the electrode body end 7N. In the initial position, the movable portion 25 is not in contact with the electrode body end 7N.

[0037] Figure 6 is an end view of the central portion 24C of the frame portion 24 cut in the width direction of the current collecting terminal 21. As shown in Figure 6, the uncoated portion 18 of the electrode body end portion 7N is divided into multiple bundles 40. The uncoated portions 18 are in close contact with each other. Each bundle 40 is inserted into an opening 26. By inserting each bundle 40 into the opening 26 in this way, the current collecting terminal 21 is positioned in the thickness direction of the electrode body end portion 7N.

[0038] 7, the free end 30 side of the movable part 25 of the current collecting terminal 21 is pressed toward the opening 26. This causes plastic deformation near the base end 29 of the movable part 25. The movable part 25 moves from the initial position to the insertion position.

[0039] In the process of moving the movable part 25 to the insertion position, the central part 25C of the movable part 25 gradually inserts the bundle 40 of uncoated parts 18 from the ends into the first groove part 31 and the second groove part 32. Because wide guide grooves 35, 37 are provided in the central part 24C of the frame part 24 and the central part 25C of the movable part 25, the uncoated parts 15, 18 will be inserted into the guide grooves 35, 37 even if the position of the bundle 40 is slightly misaligned with the position of the narrow grooves 36, 38. Because the widths of the guide grooves 35, 37 gradually decrease, the uncoated parts 15, 18 can be guided into the narrow narrow grooves 36, 38 as the movable part 25 moves.

[0040] As shown in Figure 8, when the movable part 25 moves to the insertion position, the bundle 40 protrudes from the portion of the first groove part 31 between the central part 24C of the frame part 24 and the movable part 25. In addition, the bundle 40 protrudes from the portion of the second groove part 32 between the central part 25C of the movable part 25. The narrow grooves 36, 38 (see Figure 4) have a minimum width that allows the bundle 40 of the uncoated part 18 to be inserted therethrough. Therefore, when the bundle 40 is inserted into the narrow grooves 36, 38, the bundles 40 are in a compressed state in which they are in close contact with each other.

[0041] Here, the current collecting terminal 21 of this embodiment will be compared with a current collecting terminal that has a groove but does not have a movable part 25. When attaching a current collecting terminal that has a groove but does not have a movable part 25, if an attempt is made to insert the entire electrode body end part 7 into the groove at the same time, it is expected that at least a part of the electrode body end part 7 will be displaced from the groove. The electrode body end part 7 that has been displaced from the groove will bend when it abuts against the back surface 21B of the current collecting terminal 21. The bent part does not protrude from the groove, and therefore cannot be properly welded to the current collecting terminal 21.

[0042] On the other hand, when attaching the current collecting terminal 21 of this embodiment to the electrode body end portion 7, the flat portion 23 is abutted against the electrode body end portion 7N to stabilize its posture, and the bundle 40 of uncoated portions 18 (or uncoated portions 15) is gradually inserted from the end of the central portions 24C, 25C. This makes it possible to prevent bending of the uncoated portions 18 (or uncoated portions 15). In particular, the guide grooves 35, 37 provided in the groove portion 33 make it possible to prevent bending of the uncoated portions 18 (or uncoated portions 15).

[0043] 8 is an end view of the central portion 24C of the frame portion 24 cut in the width direction of the current collecting terminal 21. As shown in FIG. 8, when the movable portion 25 is placed in the insertion position, each bundle 40 of the uncoated portions 18 protrudes from the first groove portion 31 and the second groove portion 32.

[0044] As shown in Fig. 9, the protruding portions of the bundle 40 are welded to the current collecting terminal 21N from the front surface 21A side of the current collecting terminal 21N. For example, the protruding portions are joined to the current collecting terminal 21N by laser welding, in which a laser beam is irradiated onto the protruding portions. In addition to laser welding, the bundle 40 and the current collecting terminal 21 may also be joined by arc welding, gas welding, electron beam welding, or the like. This forms a welded portion 41 where the bundle 40 of the uncoated portions 18 and the current collecting terminal 21N are joined.

[0045] Furthermore, the side portions 24A, 24B that define the guide groove 35 do not extend parallel to the longitudinal direction of the current collecting terminal 21, but extend along the guide groove 35. They have the same width as the side portions 24A, 24B that define the narrow groove 36. This minimizes the heat loss that occurs when heat from the molten portion is transferred to the surrounding unmolten frame portion 24. This makes it possible to prevent poor welding due to insufficient melting of the frame portion 24.

[0046] The effects of the above embodiment will be described. (1) By moving the movable part 25 of the current collecting terminal 21 from the initial position to the insertion position, the uncoated parts 15, 18 protruding from the opening 26 can be inserted into the first groove 31. As the movable part 25 moves, the first groove 31 gradually penetrates the uncoated parts 15, 18 from their ends. As a result, the uncoated parts 15, 18 can be more easily inserted into the groove 33, which can suppress deformation such as bending of the uncoated parts 15, 18. This allows the uncoated parts 15, 18 and the current collecting terminal 21 to be properly joined.

[0047] (2) The movable portion 25 has the second groove portion 32. Therefore, the current collecting terminal 21 and the electrode body can be joined in a state where the uncoated portions 15, 18 are divided into even smaller bundles. (3) The first groove portion 31 has a wide guide groove 35. The second groove portion 32 has a wide guide groove 37. The guide grooves 35, 37 are located on the base end 29 side, where the insertion of the uncoated portions 15, 18 begins. This allows the uncoated portions 15, 18, which tend to bend, to be easily inserted. Furthermore, the first groove portion 31 and the second groove portion 32 have narrow grooves 36, 38 that match the thickness of the bundle 40, which allows the uncoated portions 15, 18 to be compressed and properly welded.

[0048] (4) The opening 26 is surrounded by the frame 24, so that it can maintain a suitable strength. (5) The frame 24 surrounding the opening 26 extends along the shapes of the first opening 27 and the second opening 28. Therefore, when the current collecting terminal 21 and the electrode body 5 are joined by welding, heat loss in the frame 24 is suppressed, and heat can be concentrated at the contact portion between the current collecting terminal 21 and the frame 24. Therefore, welding defects can be suppressed.

[0049] <Other embodiments> The above embodiment can be modified and implemented as follows: The above embodiment and other embodiments below can be implemented in combination with each other within the scope of technical compatibility.

[0050] 10, the frame portion 24 may have different widths. Specifically, the inclined portion 24D may extend parallel to the longitudinal direction of the current collecting terminal 21 when viewed from the front surface 21A. In this configuration, the strength of the inclined portion 24D can be increased.

[0051] In the above embodiment, the guide grooves 35, 37 have a shape in which the width gradually changes. Alternatively, as shown in Figure 11, the guide grooves 55, 56 may have a constant width that is greater than the width of the narrow grooves 36, 38. This configuration also makes it easier to insert the bundle 40 of uncoated portions 15, 18.

[0052] In the above embodiment, the movable portion 25 includes one second groove portion 32, but may include a plurality of second groove portions 32. In the above embodiment, the current collecting terminal 21 includes a frame portion 24. Alternatively, the opening 26 may have a shape that opens on the opposite side from the flat portion 23. Furthermore, the second groove portion 32 may open on the free end 30 side. In this embodiment, the current collecting terminal 21 has a comb shape. In this embodiment, the movable portion 25 can also be provided to make it easier to insert the uncoated portions 15, 18 into the groove portions 33.

[0053] In the above embodiment, the first groove portion 31 and the second groove portion 32 have the guide grooves 35, 37 with large widths. Alternatively, the first groove portion 31 and the second groove portion 32 may have a constant width. Even in this embodiment, the current collecting terminal 21 includes the movable portion 25, which allows the uncoated portions 15, 18 to be inserted into the first groove portion 31 and the second groove portion 32 from their ends. Therefore, compared to a current collecting terminal 21 that does not include the movable portion 25, it is easier to insert the uncoated portions 15, 18 into the first groove portion 31 and the second groove portion 32.

[0054] In the above embodiment, the second groove 32 is formed in the movable part 25, but this may be omitted. Even in this embodiment, the first groove 31 can be formed between the opening 26 and the movable part 25, so that the bundle 40 of uncoated parts 15, 18 can be inserted into the first groove 31.

[0055] In the above embodiments, the battery 1 has been described as including a wound-type electrode assembly 5. Alternatively, the battery 1 may include a stacked-type electrode assembly. A stacked-type electrode assembly is formed by alternately stacking multiple positive electrode sheets and multiple negative electrode sheets with separators interposed therebetween. Either the positive electrode sheets or the negative electrode sheets may be housed in a pouch-shaped separator. A stacked-type electrode assembly has an end where uncoated portions of the positive electrode sheets are stacked and an end where uncoated portions of the negative electrode sheets are stacked. The current collecting terminal 21 is joined to the end of the stacked-type electrode assembly, as with the wound-type electrode assembly 5. Effects similar to those of the above embodiments can also be obtained with a battery including a stacked-type electrode assembly.

[0056] In the above embodiment, the battery 1 is embodied as a lithium-ion secondary battery. The battery may be any battery provided with a current collecting terminal. The battery may be a nickel-metal hydride secondary battery or other batteries. A nickel-metal hydride secondary battery includes a positive electrode composite containing a nickel oxide compound and a negative electrode composite containing a hydrogen storage alloy. The battery may also be a primary battery instead of a secondary battery. The positive electrode sheet and the negative electrode sheet may not include an electrode composite layer and may be made of a metal material.

[0057] The battery 1 may be used in vehicles such as electric vehicles, hybrid vehicles, gasoline vehicles, diesel vehicles, and other mobile objects. Alternatively, the battery 1 may be installed as a fixed power generating device for purposes other than as an energy source for mobile objects. [Explanation of symbols]

[0058] 5...Electrode body 13, 16...Current collector 14,17...electrode composite layer 15,18...Uncoated area 21...Current collector terminal 22...Support part 25...Movable part 26...Opening 31, 32...Groove

Claims

1. an electrode assembly including a plurality of sheet-shaped current collectors and electrode mixture layers provided on the current collectors, the electrode assembly having uncoated portions where the current collectors are exposed; a current collecting terminal joined to an end of the electrode body where the uncoated portion is laminated, The current collecting terminal is a support portion having an opening through which a portion of the end portion of the electrode body protrudes; a movable portion having a base end connected to the support portion and a free end located on the opposite side of the base end, the movable portion being movable from an initial position to a penetration position in contact with the end of the electrode body when an external force is applied; A battery in which a groove portion for inserting the uncoated portion is formed between the movable portion and the support portion at the insertion position.

2. The battery according to claim 1 , wherein the groove portion has a width different from that of the uncoated portion, the width of the groove portion being greater than the width of the free end portion.

3. The groove formed between the support portion and the movable portion is a first groove, The battery according to claim 1 , wherein the movable portion has a second groove portion that is a groove portion extending in the axial direction.

4. The battery according to claim 3 , wherein the portion of the second groove through which the uncoated portion is inserted has different widths, the width of the base end side being larger than the width of the free end side.

5. The battery according to claim 1 , wherein the support portion has a frame portion surrounding the opening.

6. The opening has a wide portion whose width is increased, The battery according to claim 5 , wherein the frame portion extends along the shape of the opening portion.

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