Method for joining current collectors, joining structure for current collectors, and battery

Abstract

To suitably join a current collector to an electrode plate end part.SOLUTION: A secondary battery comprises a current collector 60 that is joined to an axial end 10e of an electrode body 10 subjected to arrangement of a plurality of electrode plate end parts 40 stacked in a thickness direction. When the current collector 60 is joined, a step of integrally coating each of the electrode plate end parts 40 with a resin in its joining position, and a step of solid phase-bonding a joining area 61 of the current collector 60 to an edge part 70 of each of the electrode plate end parts 40 integrated by a coating part 81 formed of the resin are executed.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a method for joining current collectors, a joining structure of current collectors, and a battery.

Background Art

[0002] Generally, for example, in a battery including an electrode body formed by laminating positive and negative electrodes with a separator interposed therebetween, the electrode body is connected to an external terminal through a current collector serving as a connection member while being housed in a case.

[0003] That is, each electrode forming the electrode body has an uncoated portion where the electrode active material is not applied at the end of its electrode plate. Further, these end portions of the electrode plates are arranged side by side in the thickness direction for each of the positive and negative polarities at the end position of the electrode body. And in many cases, each current collector on the positive electrode side and the negative electrode side is configured to be joined to a current collecting foil portion bundling these end portions of the electrode plates.

[0004] However, when such a current collecting foil structure is adopted, a larger tensile load is applied to the end portion of the electrode plate farther from the position serving as a reference for the current collecting foil. As a result, breakage of the end portion of the electrode plate due to such a tensile load, that is, so-called "foil breakage" or the like is likely to occur. And in order to alleviate the problem of the tensile load generated by such current collecting foil, by widely setting the uncoated portion that is easily plastically deformed, there is a problem that the area where the electrode active material is applied on the electrode plate, that is, the formation area of the electrode active material layer that effectively functions as an electrode becomes small.

[0005] On the other hand, for example, Patent Document 1 discloses a configuration in which a joining surface of a current collector is joined to an edge portion of each electrode plate end portion having a configuration as the uncoated portion without current collecting the end portions of each electrode plate. And in addition to this, it is described that by bending the edge portion of each electrode plate end portion into a substantially L shape, the joining area of the current collector is enlarged.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2006-32112 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, typically, the edges of the electrode plates are in the form of extremely thin foil. Therefore, in the conventional bonding structure described above, when the current collectors are bonded, the edges of each electrode plate, which are arranged in line in the thickness direction, may deform irregularly. This makes it difficult to ensure a uniform bonding state. [Means for solving the problem]

[0008] This document describes a method for joining current collectors, a joining structure for current collectors, and various types of batteries that solve the above problems. Embodiment 1 is a method for joining a current collector to an electrode body having a plurality of electrode plate ends arranged in the thickness direction, comprising the steps of: integrally covering each electrode plate end with a resin at the joining position of the current collector; and solid-state joining the joining portion of the current collector to the edges of each electrode plate end integrated by the covering portion formed by the resin.

[0009] According to the above configuration, by joining the joint portion of the current collector to the edges of each plate end, which are reinforced by being fixed as a single unit, the edges of each plate end, which are arranged in line in the thickness direction, are less likely to separate during joining. This prevents irregular deformation and ensures a uniform joining state of the current collector to the edges of each plate end. In addition, the joining position of the current collector to each plate end can be freely set.

[0010] Furthermore, by using solid-phase bonding, heat generation during bonding can be suppressed, thereby avoiding thermal degradation such as deterioration of the electrode active material due to that heat. In addition, the generation of sputtering, also known as scattering, can be suppressed. As a result, the current collector can be more suitably bonded to the ends of each electrode plate.

[0011] Embodiment 2 is a method for joining a current collector according to Embodiment 1, further comprising the step of partially removing the resin to expose the edges of each electrode plate end from the covering portion. According to the above configuration, the current collector can be easily attached to the edge of each electrode plate end. This allows for a more favorable attachment of the current collector to each electrode plate end.

[0012] Embodiment 3 is a method for joining a current collector according to Embodiment 1 or Embodiment 2, which includes a step of bending the edges of each electrode plate end that are exposed from the covering portion. According to the above configuration, the joining can be performed more easily. In addition, a uniform joining state can be ensured. As a result, the current collector can be more preferably joined to the end of each electrode plate.

[0013] Embodiment 4 is a method for joining current collectors according to any one of Embodiments 1 to 3, wherein the solid-phase joining uses a composite vibration joining or electromagnetic pressure joining. In other words, by employing these characteristic solid-phase bonding processes, heat generation during bonding can be effectively suppressed, thereby preventing thermal deformation and the generation of flying debris. Furthermore, even if there is an excess coating area that includes the end faces of each electrode plate and places the edges of each electrode plate end within the coating area, this excess coating area is removed during the solid-phase bonding process. As a result, the current collector can be bonded to the edges of each electrode plate end more easily and stably.

[0014] Embodiment 5 is a method for joining current collectors according to any one of Embodiments 1 to 4, wherein the resin used is a photocurable resin. According to the above configuration, a stable coating portion can be easily formed. In addition, there is an advantage that the formation time is short.

[0015] Aspect 6 is a current collector joining structure for joining a current collector to an electrode body having a plurality of electrode plate end portions arranged side by side in the thickness direction, and is configured using a resin that integrally coats each electrode plate end portion at the joining position of the current collector. And a joining portion of the current collector joined to an edge portion of each electrode plate end portion exposed from the coating portion.

[0016] According to the above configuration, a suitable joining state of the current collector to the electrode plate end portion can be ensured. Aspect 7 is the current collector joining structure according to aspect 6, in which the edge portions of each electrode plate end portion are joined to the joining portion in a bent state.

[0017] According to the above configuration, a more suitable joining state of the current collector to the electrode plate end portion can be ensured. Aspect 8 is a battery having the current collector joining structure according to aspect 6 or aspect 7.

[0018] According to the above configuration, a suitable joining state of the current collector to the electrode plate end portion can be ensured. And thereby, excellent battery performance and high reliability can be ensured.

Effects of the Invention

[0019] According to the present invention, a current collector can be more suitably joined to an electrode plate end portion.

Brief Description of the Drawings

[0020] [Figure 1] It is a perspective view of a secondary battery. [Figure 2] It is an exploded view of an electrode body. [Figure 3] It is a side view of a secondary battery. [Figure 4] It is a side view of an electrode body and a current collector. [Figure 5] It is a side view of an electrode body and a current collector. [Figure 6] It is a plan view showing the bonding position of the current collector with respect to the electrode body. [Figure 7] It is a side view of an electrode body provided with a covering portion that covers and integrally fixes each end portion of the electrode plates arranged in the thickness direction at the axial end portions. [Figure 8] It is a cross-sectional view of the covering portion made of resin and each end portion of the electrode plates covered by this covering portion. [Figure 9] It is a flowchart showing the formation procedure of the covering portion. [Figure 10] It is an image diagram of the solid-phase bonding process of the current collector with respect to the edge of each end portion of the electrode plates integrated by the covering portion. [Figure 11] It is an image diagram of composite vibration bonding. [Figure 12] It is an image diagram of electromagnetic pressure welding. [Figure 13] It is an image diagram of electromagnetic pressure welding. [Figure 14] It is a cross-sectional view of the current collector joined to the edge of each end portion of the electrode plates integrated by the covering portion. [Figure 15] It is a cross-sectional view of a covering portion of another example and each end portion of the electrode plates. [Figure 16] It is a cross-sectional view of a covering portion of another example and each end portion of the electrode plates. [Figure 17] It is a cross-sectional view showing another example of a joining method in which the edge of each end portion of the electrode plates is exposed by partially removing the resin forming the covering portion. [Figure 18] It is a cross-sectional view showing another example of a joining method in which the edge of each end portion of the electrode plates exposed from the covering portion is bent. [Figure 19] It is a cross-sectional view showing another example of a joining structure in which a current collector is joined to the edge of each end portion of the electrode plates that has been bent. [Figure 20] It is a side view of an electrode body showing another example regarding the bonding position of the current collector with respect to each end portion of the electrode plates.

Mode for Carrying Out the Invention

[0021] Hereinafter, an embodiment relating to a current collector joining method and joining structure will be described with reference to the drawings. (Secondary battery) As shown in Figure 1, the secondary battery 1 comprises an electrode body 10 that integrates a positive electrode 3, a negative electrode 4, and a separator 5, and a case 20 that houses this electrode body 10. The secondary battery 1 of this embodiment has a lithium-ion secondary battery configuration in which the electrode body 10 inside the case 20 is impregnated with a non-aqueous electrolyte (not shown).

[0022] More specifically, in the secondary battery 1 of this embodiment, the positive electrode 3, the negative electrode 4, and the separator 5 are stacked together, each having a sheet-like outer shape. The electrode body 10 of this embodiment is constructed as a wound body 10X in which these electrodes and the separator 5 are arranged radially, with the separator 5 sandwiched between the positive electrode 3 and the negative electrode 4, by winding the stack of these positive electrode 3, the negative electrode 4, and the separator 5.

[0023] Furthermore, the case 20 of this embodiment comprises a flattened, roughly rectangular box-shaped case body 21 and a lid member 22 that closes the open end 21x of the case body 21. In the secondary battery 1 of this embodiment, the electrode body 10, which is the wound body 10X, has a flattened wound shape that corresponds to the box shape of the case 20.

[0024] (Electrode sheet and electrode body) As shown in Figure 2, in the secondary battery 1 of this embodiment, the positive electrode 3 and the negative electrode 4 each have a configuration as an electrode sheet 35 comprising an electrode plate 31 having a sheet-like outer shape and an electrode active material layer 32 laminated on the electrode plate 31.

[0025] Specifically, for the electrode sheet 35P for the positive electrode 3, a composite paste containing lithium transition metal oxide, which serves as the positive electrode active material, is coated onto the electrode plate 31P on the positive electrode 3 side, which is made of aluminum or the like. Similarly, for the electrode sheet 35N for the negative electrode 4, a composite paste containing carbon-based material, which serves as the negative electrode active material, is coated onto the electrode plate 31N on the negative electrode 4 side, which is made of copper or the like. These composite pastes each contain a binder. In the secondary battery 1 of this embodiment, when these composite pastes dry, the corresponding positive electrode active material layer 32P and negative electrode active material layer 32N are formed on the positive and negative electrode sheets 35P and 35N, respectively.

[0026] Furthermore, in the secondary battery 1 of this embodiment, the positive and negative electrode sheets 35P and 35N are each shaped into strips. The electrode body 10 of this embodiment is configured such that the positive and negative electrode sheets 35P and 35N, which are stacked with a separator 5 in between, are wound around a winding axis L that extends in the width direction (left-right direction in Figure 2) of the strip shape.

[0027] In Figure 2, the separator 5 and each electrode sheet 35 are wound in such a way that the electrode sheet 35P constituting the positive electrode 3 is wound inward. However, this figure is just one example of the structure of the electrode body 10, and in some cases, the separator 5 and each electrode sheet 35 may be wound in such a way that the electrode sheet 35N constituting the negative electrode 4 is wound inward. This determines whether the electrode sheet 35 placed on the outermost shell of the electrode body 10 is the electrode sheet 35P constituting the positive electrode 3 or the electrode sheet 35N constituting the negative electrode 4.

[0028] (External terminals and connecting members) Furthermore, as shown in Figures 1 to 3, the lid member 22 of the case 20 is provided with a positive electrode terminal 38P and a negative electrode terminal 38N that protrude to the outside of the case 20, serving as external terminals 38 of the secondary battery 1. In addition, each electrode sheet 35 has an uncoated portion 39 formed on its electrode plate 31 where the electrode active material layer 32 is not formed. Specifically, in this embodiment, each electrode sheet 35 has an uncoated portion 39 at the widthwise ends of each electrode plate 31P, 31N, which are formed into a strip shape and coated with a composite paste containing the electrode active material, i.e., the electrode plate end 40P on the positive electrode 3 side and the electrode plate end 40N on the negative electrode 4 side. The secondary battery 1 of this embodiment is configured such that the electrode sheet 35P constituting the positive electrode 3 and the positive electrode terminal 38P are electrically connected, and the electrode sheet 35N constituting the negative electrode 4 and the negative electrode terminal 38N are electrically connected, utilizing these uncoated portions 39.

[0029] That is, as shown in Figure 2, in the electrode body 10 of this embodiment, with each electrode sheet 35 and separator 5 wound up, the electrode plate end 40P on the positive electrode 3 side, which has an uncoated portion 39, is positioned at the first axial end 10ea (the left end in Figure 2). The electrode plate end 40N on the negative electrode 4 side, which also has an uncoated portion 39, is positioned at the second axial end 10eb (the right end in Figure 2).

[0030] Furthermore, as shown in Figures 1 and 3, the electrode body 10 of this embodiment is housed in the case 20 with its winding axis L aligned along the longitudinal direction (left-right direction in Figure 3) of the lid member 22, which is a long, roughly rectangular plate. In this configuration, the secondary battery 1 of this embodiment is configured such that the electrode plate end 40P on the positive electrode 3 side and the electrode plate end 40N on the negative electrode 4 side are connected to their corresponding positive terminal 38P and negative terminal 38N, respectively, via positive and negative connecting members 50P and 50N.

[0031] Furthermore, in the secondary battery 1 of this embodiment, with the electrode body 10 housed in the case 20 as described above, a fluorine-based electrolyte 51 is injected into the case 20. This electrolyte 51 is prepared by dissolving a lithium salt, which serves as a supporting salt, in an organic solvent. Thus, the secondary battery 1 of this embodiment is configured such that the electrolyte 51 impregnates the electrode body 10 housed in the case 20.

[0032] (Current collector) Next, in the secondary battery 1 of this embodiment configured as described above, the current collector that constitutes a connecting member between the electrode body 10 and the external terminal will be described.

[0033] As shown in Figures 4 and 5, the electrode body 10 of this embodiment has a configuration as a wound body 10X, so that its positive and negative electrode plate ends 40 are arranged side by side in the thickness direction at its axial end 10e. Furthermore, the secondary battery 1 of this embodiment is equipped with current collectors 60 that are joined to each of the axial ends 10e of these electrode body 10. That is, as described above, the positive and negative electrode plate ends 40 arranged at each of the axial ends 10e of these electrode body 10 each have a configuration as an uncoated portion 39 on the electrode plate 31 where the electrode active material layer 32 is not formed (see Figure 2). Thus, the secondary battery 1 of this embodiment is configured so that each of these current collectors 60 acts as a positive and negative connecting member 50, electrically connecting the positive electrode 3 and negative electrode 4 constituting the electrode body 10 to their corresponding positive and negative external terminals 38.

[0034] Specifically, the current collector 60 of this embodiment includes a joint portion 61 joined to the axial end 10e of the electrode body 10, and an extension portion 62 continuous with the joint portion 61. In the current collector 60 of this embodiment, the joint portion 61 and the extension portion 62 have an elongated, substantially flat outer shape that extends along the direction (up and down in each figure) in which the edges 70 of each electrode plate end 40 extend at the axial end 10e of the electrode body 10. That is, the joint portion 61 of the current collector 60 of this embodiment is joined to the edges 70 of each electrode plate end 40 located at the axial end 10e of the electrode body 10. Furthermore, in the current collector 60 of this embodiment, the extension portion 62 extending from one longitudinal end of the joint portion 61 is connected to an external terminal 38 provided on its cover member 22. Note that in the current collector of this embodiment, the joint portion 61 is formed to be wider than the extension portion 62. In this embodiment, the secondary battery 1 is configured such that the current collector 60 functions as either a positive or negative connecting member 50 corresponding to the polarity of each electrode plate end 40 to which its joint portion 61 is joined.

[0035] (Arrangement of current collectors) As shown in Figure 6, the electrode body 10 of this embodiment has a configuration as a wound body 10X, and has first and second axial ends 10ea and 10eb where the electrode plate ends 40P and 40N of opposite polarities are arranged. Furthermore, this electrode body 10 has a flattened wound shape with first and second flattened surfaces S1 and S2 facing in opposite directions. Moreover, in this embodiment, the electrode body 10 has a configuration in which the current collector 60 is joined to the long side portion 80a on the first flattened surface S1 side at the first axial end 10ea, and the current collector 60 is joined to the long side portion 80b on the second flattened surface S2 side at the second axial end 10eb.

[0036] (Current collector joining structure and joining method) As shown in Figures 5 to 8, the electrode body 10 of this embodiment includes a covering portion 81 that integrally covers each electrode plate end 40 positioned at the joining position of the current collector 60 to the axial end 10e of the electrode body 10. That is, in the electrode body 10 of this embodiment, this covering portion 81 is provided on the long side portion 80 on one side to which either the positive or negative current collector 60 is joined. The secondary battery 1 of this embodiment is configured such that the joining portion 61 of the current collector 60 is joined to the edge portion 70 of each electrode plate end 40 which is integrated by this covering portion 81.

[0037] More specifically, as shown in Figure 8, the covering portion 81 of this embodiment is formed using resin. The secondary battery 1 of this embodiment is configured to use a photocurable resin 82 as the resin that forms this covering portion 81.

[0038] Specifically, as shown in Figure 9, in the electrode body 10 of this embodiment, first, a liquid photocurable resin 82 is applied to each electrode plate end 40 positioned at the joining position of the current collector 60 (step 101). For example, an acrylic or epoxy photocurable resin can be used as the photocurable resin 82. Next, ultraviolet light is irradiated onto the photocurable resin 82 applied to each electrode plate end 40 (step 102, UV irradiation). Furthermore, the photocurable resin 82 solidified by this UV irradiation forms a coating portion 81. Then, in the electrode body 10 of this embodiment, each electrode plate end 40 positioned at the joining position of the current collector 60 is integrated by the coating portion 81 formed thereon (step 103).

[0039] Furthermore, as shown in Figure 10, in the electrode body 10 of this embodiment, the joint portion 61 of the current collector 60 is assembled to the covering portion 81 from the axial side, that is, from the direction facing the end faces 40s of each electrode plate end 40 covered by the covering portion 81 (upper side in the figure). Then, in this embodiment, the current collector 60 is configured such that its joint portion 61 is joined to each electrode plate end 40 by a solid-phase bonding process.

[0040] Specifically, as shown in Figure 11, a composite vibration bonding process can be used for the solid-state bonding process of the current collector 60 to each electrode plate end 40. That is, composite vibration bonding is a type of ultrasonic bonding and is sometimes called ultrasonic composite vibration bonding. Its characteristic feature is that, unlike general ultrasonic bonding, the bonding tool 83 that vibrates the bonding portion 61 of the current collector 60 vibrates in an arc shape. Furthermore, this characteristic vibration trajectory of the bonding tool 83 enables bonding with a smaller amplitude. As a result, the heat generated when bonding the bonding portion 61 of the current collector 60 to the edge portion 70 of each electrode plate end 40 is suppressed, thereby suppressing thermal denaturation such as deterioration of the electrode active material due to heat and the generation of sputtering material.

[0041] Furthermore, as shown in Figures 12 and 13, electromagnetic pressure welding can be used as the solid-state bonding process for the current collector 60 to each plate end 40. That is, electromagnetic pressure welding is a method of bonding materials by using electromagnetic force, and is sometimes called electromagnetic seam welding. Specifically, a drive power supply 85 equipped with a large-capacity capacitor 84 is used to instantaneously supply a large current to the acceleration coil 86. Then, based on the electromagnetic force generated thereby, the joint portion 61 of the current collector 60 is accelerated, and this joint portion 61 of the current collector 60 is pressed against the edge portion 70 of each plate end 40.

[0042] Furthermore, this electromagnetic pressure welding has the characteristic of generating little heat during joining because the joint portion 61 of the current collector 60 is instantaneously joined to the edge portion 70 of each electrode plate end portion 40. As a result, similar to the composite vibration joint described above, thermal deformation and the generation of flying debris can be suppressed.

[0043] Furthermore, as shown in Figures 8, 10, and 11, in the electrode body 10 of this embodiment, a covering portion 81 is formed that integrally covers the edges 70 of each electrode plate end 40, including the end faces 40s of each electrode plate end 40, which are positioned at the joining position of the current collector 60. Moreover, any excess covering area α provided in this covering portion 81 is removed during the joining process by using the above-mentioned composite vibration bonding or electromagnetic pressure welding in the solid-state bonding process. Specifically, in composite vibration bonding, the resin of the excess covering area α is pushed into the gap between each electrode plate end 40 by the excitation, and in electromagnetic pressure welding, by the electromagnetic acceleration.

[0044] As shown in Figure 14, the secondary battery 1 of this embodiment is configured such that the joint portion 61 of the current collector 60 is joined to the edges 70 of each electrode plate end 40 exposed from the covering portion 81, more specifically, to the end faces 40s of each electrode plate end 40.

[0045] (action) Specifically, by joining the joint portion 61 of the current collector 60 to the edges 70 of each electrode plate end 40, which are reinforced by being covered and fixed together by the resin coating portion 81, the edges 70 of each electrode plate end 40 are less likely to separate during joining. As a result, a stable and uniform joining state is ensured without irregular deformation of each electrode plate end. In addition, by using a solid-phase bonding process in the joining process, heat generation during joining is suppressed.

[0046] Next, the effects of this embodiment will be described. (1) The secondary battery 1 includes a current collector 60 that is joined to the axial end 10e of an electrode body 10, which has a plurality of electrode plate ends 40 arranged in the thickness direction. When joining the current collector 60, the following steps are performed: one step of integrally covering each electrode plate end 40 with resin at the joining position, and the other step of solid-state bonding the joining portion 61 of the current collector 60 to the edges 70 of each electrode plate end 40 which are integrated by the covering portion 81 formed by the resin.

[0047] According to the above configuration, when joining, the edges 70 of each electrode plate end 40, which are arranged in line in the thickness direction, are less likely to separate. This prevents irregular deformation and ensures a uniform joining state of the current collector 60 to the edges 70 of each electrode plate end 40. In addition, the joining position of the current collector 60 to each electrode plate end 40 can be freely set.

[0048] Furthermore, by using solid-phase bonding, heat generation during bonding can be suppressed, thereby avoiding thermal degradation such as deterioration of the electrode active material due to that heat. In addition, the generation of sputtering, also known as sputtering, can be suppressed. As a result, the current collector 60 can be more preferably bonded to each electrode plate end 40.

[0049] (2) For solid-state bonding, composite vibration bonding or electromagnetic pressure welding shall be used. In other words, by employing these characteristic solid-phase bonding processes, heat generation during bonding can be effectively suppressed, thereby preventing thermal deformation and the generation of flying debris. Furthermore, even if there is an excess coating area α that includes the end face 40s of each electrode plate end 40, and places the edge 70 of each electrode plate end 40 within the coating area 81, this excess coating area α is removed during the solid-phase bonding process. As a result, the current collector 60 can be bonded to the edge 70 of each electrode plate end 40 more easily and stably.

[0050] (3) A photocurable resin 82 is used to form the covering portion 81 that covers and integrally fixes the edges 70 of each electrode plate end 40. This makes it possible to easily form the stable covering portion 81. In addition, there is the advantage of a short formation time.

[0051] The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0052] In the above embodiment, compound vibration bonding and electromagnetic pressure welding were exemplified as forms of solid-state bonding used to join the current collector 60 to each electrode plate end 40. However, the invention is not limited to these, and other solid-state bonding processes, such as general ultrasonic bonding, may be used as long as bonding can be performed in a solid state without causing excessive temperature rise.

[0053] In the above embodiment, an excess covering area α is formed in which the edge portion 70 of each electrode plate end 40, including the end face 40s of each electrode plate end 40, is placed within the covering portion 81. However, the configuration is not limited to this, and the covering portion 81 may be formed with the edge portion 70 of each electrode plate end 40 already exposed.

[0054] For example, as shown in Figure 15, the covering portion 81B may be formed such that the end face 40s of each electrode plate end 40 is flush with the surface 81s of the covering portion 81B. Furthermore, as shown in Figure 16, the covering portion 81C may be formed such that the end faces 40s of each electrode plate end 40 protrude from the surface 81s of the covering portion 81C.

[0055] Furthermore, as shown in Figures 17 to 19, after forming the covering portion 81D, the resin forming this covering portion 81D is partially removed. The resin removal process shown in Figure 17 is performed, for example, by so-called laser ablation using a UV pulsed laser. After this removal process, the edges 70 of each electrode plate end 40 exposed from the covering portion 81D' are bent. Note that the bending process of each electrode plate end 40 shown in Figure 18 is preferably performed using a jig or the like to form a uniform, approximately L-shaped bend. Then, as shown in Figure 19, the joint portion 61 of the current collector 60 is joined to the edges 70' of each bent electrode plate end 40.

[0056] In other words, by partially removing the resin and exposing the edges 70 of each electrode plate end 40 from the covering portion 81D', the current collector 60 can be easily joined to these edges 70 of each electrode plate end 40. Furthermore, by bending the edges 70 of each electrode plate end 40 exposed from the covering portion 81D' into a roughly L-shape, joining can be performed even more easily, and a uniform joining state can be ensured. As a result, the current collector 60 can be joined to each electrode plate end 40 more favorably.

[0057] In the above embodiment, the current collector 60 is joined to the edges 70 of each electrode plate end 40 located on the long side 80 of the flattened spiral shape at the axial end 10e of the electrode body 10. However, the joining position of the current collector 60 to the electrode body 10 is not limited to this and can be set arbitrarily.

[0058] For example, as shown in Figure 20, an additional electrode body 10F is provided, in which a covering portion 81F is formed on the curved portion 90 of its wound shape. The current collector 60F may then be solid-bonded to the edges 70 of each electrode plate end 40, which are integrated by this covering portion 81F.

[0059] In the above embodiment, a photocurable resin 82 was used to form the covering portion 81. However, the resin used to form the covering portion 81 may be changed as long as it is possible to cover and integrate each electrode plate end 40, that is, to fix each electrode plate end 40 in an integral state. The photocurable resin 82 has the advantage that it is easy to form the covering portion 81 and the formation time is short.

[0060] Furthermore, in the above alternative example, a UV pulsed laser was used for the resin removal process, but other configurations, such as using infrared light of 1 μm or more, may also be used. Additionally, the resin removal process may be carried out by a method other than so-called laser ablation.

[0061] In the above embodiment, the current collector 60 is provided with a joint portion 61 at the axial end 10e of the electrode body 10, which has an elongated, substantially flat outer shape extending along the direction in which the edges 70 of each electrode plate end 40 extend. However, the shape of the current collector 60 is not limited to this and can be arbitrarily changed. However, from the viewpoint of ensuring a uniform bonding state and stably bonding the current collector 60 to the edges 70 of each electrode plate end 40, it is desirable that the joint portion 61 of the current collector 60 has a flat bonding surface 61s.

[0062] In the above embodiment, the configuration is embodied in which positive and negative electrode sheets 35P and 35N, stacked with a separator 5 in between, are wound together to form the electrode body 10 of the secondary battery 1. However, the configuration is not limited to this, and may also be applied to a configuration in which a current collector 60 is joined to a planar stacked electrode body 10.

[0063] Furthermore, the above embodiment embodied a method for manufacturing a secondary battery 1 having the configuration of a lithium-ion secondary battery. However, it is not limited to this and may be applied to other types of batteries as well. The shape of the external terminals is not limited to the shapes shown in each figure, such as Figure 1 and Figure 20, and may be changed as desired. Similarly, the shape of the case 20, which forms the outer shape of the secondary battery 1, is not necessarily limited to a flat rectangular box shape, but may be changed as desired, for example, to a cylindrical shape. [Explanation of Symbols]

[0064] 1…Secondary battery 10...Electrode body 10e...Axial end 40…Pole plate end 60... Current collector 61…Joint part 70...edge

Claims

1. A method for joining a current collector, comprising joining a current collector to an electrode body having a plurality of electrode plate ends arranged in the thickness direction, The process involves integrally covering the ends of each electrode plate with resin at the joining position of the current collector, A method for joining a current collector, comprising the step of solid-state bonding the joint portion of the current collector to the edges of each electrode plate end, which are integrated by the coating portion formed by the resin.

2. The method for joining a current collector according to claim 1, further comprising the step of partially removing the resin to expose the edges of each electrode plate end from the covering portion.

3. The process includes bending the edges of each electrode plate end that are exposed from the covering portion. The method for joining current collectors according to claim 2.

4. The solid-state joint is performed using a composite vibration joint or electromagnetic pressure welding. The method for joining current collectors according to claim 1.

5. The method for joining current collectors according to claim 1, wherein the resin is a photocurable resin.

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