Method of manufacturing secondary battery and secondary battery

Abstract

To provide a method of manufacturing a secondary battery capable of enlarging a battery capacity while suppressing the cost of manufacture due to an increase in the number of components.SOLUTION: A method of manufacturing a secondary battery comprising an electrode body 40, a battery terminal etc., includes: a junction step of joining a downstream side of a positive electrode tab group 51 extending from an end face of the electrode body 40 in an extension direction to a junction surface Ma of a collector terminal 27 in a positive electrode battery terminal and joining a downstream side of a negative electrode tab group 56 in the extension direction to a junction surface Mb of a collector terminal 28 in a negative electrode battery terminal; and an alignment step of relatively moving the positive electrode battery terminal, the negative electrode battery terminal and the electrode body 40 in a Y-axis direction, folding the positive electrode tab group 51 and the negative electrode tab group 56 toward the side of the electrode body 40 in end portions 27b1 and 28b1 of electrode junction parts 27b and 28b along surface shapes of the electrode junction parts 27b and 28b of the collector terminals 27 and 28, and aligning the electrode body 40 between the positive electrode battery terminal and the negative electrode battery terminal.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a secondary battery and a secondary battery. [Background technology]

[0002] Conventionally, secondary batteries used in electric vehicles such as electric automobiles that use a motor as a drive source include an electrode assembly, a case that houses the electrode assembly, battery terminals that are attached to the case and electrically connected to the electrode assembly, etc. As a secondary battery that includes such an electrode assembly, for example, a battery manufactured by the method disclosed in Patent Document 1 has been proposed.

[0003] In the battery described in Patent Document 1, the battery terminal is composed of a first current collector and a second current collector, and a group of tabs extending from the electrode body are connected to the second current collector in a folded state, and the second current collector is welded to the first current collector. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 060009 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the battery disclosed in Patent Document 1 requires a process for joining the first current collector and the second current collector, which increases the equipment costs and the cost of processing the parts. Furthermore, the second current collector has recesses and through-holes necessary for welding, which increases the cost of the parts. Furthermore, the joints between the first and second current collectors overlap, which reduces the volume of the electrode assembly in the case. Thus, the battery disclosed in Patent Document 1 has room for improvement in terms of manufacturing costs and battery capacity due to the large number of parts.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a method for manufacturing a secondary battery that can increase battery capacity while suppressing manufacturing costs due to an increase in the number of parts, and a secondary battery. [Means for solving the problem]

[0007] The method for producing a secondary battery according to the present invention for achieving the above object is characterized by the following features: A method for manufacturing a secondary battery comprising: a housing having an opening; a lid attached to the opening of the housing; a flat electrode assembly formed by laminating a positive electrode material and a negative electrode material with a separator interposed therebetween; and a positive electrode battery terminal and a negative electrode battery terminal each attached to the lid, the electrode body has a band-shaped positive electrode tab group formed by stacking tabs of the positive electrode material extending from one end face in a second direction orthogonal to a first direction that is a thickness direction of the electrode body, and a band-shaped negative electrode tab group formed by stacking tabs of the negative electrode material extending from the other end face in the second direction, the positive battery terminal and the negative battery terminal have current collecting terminals including plate-shaped electrode joints disposed along the end faces of the electrode body between the housing and each end face of the electrode body in the second direction, the electrode joint portion has a surface facing the housing as a joint surface, a joining process in which a downstream side of the extension direction of the positive electrode tab group is joined to the joining surface of the current collector terminal of the positive battery terminal, and a downstream side of the extension direction of the negative electrode tab group is joined to the joining surface of the current collector terminal of the negative battery terminal; and an alignment step of, after the joining step, moving the positive and negative battery terminals and the electrode body relative to each other along the first direction, folding back the ends of the electrode junctions in the first direction toward the electrode body while aligning the positive and negative tab groups with the surface shapes of the electrode junctions of the current collector terminals, and aligning the electrode body between the positive and negative battery terminals.

[0008] According to the above-described characteristic configuration, since the battery terminal has a current collecting terminal including a plate-shaped electrode joint portion, when attaching the electrode body to the current collecting terminal, which is the battery terminal, a process for joining the components that make up the current collecting terminal is not required. Furthermore, processing such as providing a through-hole in part of the current collecting terminal for joining to other components is also not required. Therefore, processing costs and equipment costs related to the battery terminal can be reduced, and the manufacturing costs of the secondary battery can be reduced. Furthermore, the components constituting the current collecting terminal do not overlap with each other, thereby preventing the current collecting terminal from becoming larger. Therefore, with a secondary battery manufactured by the above manufacturing method, the dimension of the electrode body in the second direction can be secured to be long, thereby increasing the battery capacity, without changing the shape of the casing to increase its size.

[0009] Further features of the method for producing a secondary battery according to the present invention include: In the alignment process, at least a portion of the positive electrode tab group and the negative electrode tab group are stored in a state where they are folded back once or multiple times between the respective electrode joints and the end faces of the electrode body in the second direction.

[0010] According to the above-described characteristic configuration, in addition to folding back at the end of the electrode joint, one or more additional foldings are performed, resulting in multiple folding backs in the alignment process. By folding back multiple times in this manner in the alignment process, it is possible to align the electrode assembly while absorbing the difference between the inner and outer circumferences of the tabs that make up each tab group when stored.

[0011] Further features of the method for producing a secondary battery according to the present invention include: The electrode junction is chamfered.

[0012] According to the above characteristic configuration, damage to the tab group can be suppressed when the tab group is bent so as to conform to the surface shape of the electrode joint portion.

[0013] Further features of the method for producing a secondary battery according to the present invention include: The joint surface of the electrode joint portion is inclined so that the distance to the electrode body decreases toward one side in the first direction.

[0014] According to the above characteristic configuration, when each tab group is folded toward the electrode body, it is folded along the inclined joint surface. Therefore, the bendability of the tab group is improved, and the tab group can be stored in a state where it is aligned with the inclined joint surface of the electrode joint portion. Furthermore, the improved storage property of the tabs allows the dimension of the electrode body in the first direction to be increased, and the capacity of the secondary battery can also be increased.

[0015] The secondary battery according to the present invention has the following characteristic configuration: A secondary battery comprising: a housing having an opening; a lid attached to the opening of the housing; a flat electrode body formed by laminating a positive electrode material and a negative electrode material with a separator interposed therebetween; and a positive electrode battery terminal and a negative electrode battery terminal each attached to the lid, The electrode body is It is housed inside the housing, a band-shaped positive electrode tab group formed by stacking tabs of the positive electrode material extends from one end face in a second direction orthogonal to a first direction which is the thickness direction of the electrode body, and a band-shaped negative electrode tab group formed by stacking tabs of the negative electrode material extends from the other end face, the positive battery terminal and the negative battery terminal have current collecting terminals including electrode junctions; the electrode joint portion is a plate-like member disposed along the end surface of the electrode body between each end surface of the electrode body in the second direction and the housing, and a surface facing the housing is a joint surface; The positive electrode tab group and the negative electrode tab group are joined at the downstream side in the extension direction to the joining surfaces of the current collecting terminals of the positive electrode battery terminal and the negative electrode battery terminal, and are folded back toward the electrode body at the end of the electrode joining portion in the first direction while following the surface shape of the electrode joining portion of each of the current collecting terminals, and are stored between each of the electrode joining portions and the end face of the electrode body in the second direction.

[0016] According to the above-described characteristic configuration, since the battery collector terminal has a current collecting terminal including a plate-shaped electrode joint portion, when attaching the electrode body to the current collecting terminal, which is the battery terminal, a process for joining the components that make up the current collecting terminal is not required. Furthermore, processing such as providing a through hole in the current collecting terminal for joining to other components is also not required. Therefore, the secondary battery can reduce processing costs and equipment costs related to the battery terminal. Furthermore, the components constituting the current collecting terminal do not overlap with each other, which would increase the size of the current collecting terminal. Therefore, the secondary battery can secure a long dimension in the second direction of the electrode body and increase the battery capacity without changing the shape of the casing to increase the size of the casing. [Effects of the Invention]

[0017] As described above, the method for manufacturing a secondary battery and the secondary battery according to the present invention can increase the battery capacity while suppressing an increase in the number of parts. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is an exploded perspective view of a secondary battery according to a first embodiment; [Figure 2] FIG. 1 is a cross-sectional view showing a schematic configuration of a secondary battery. [Figure 3] FIG. 2 is a perspective view showing a partially developed electrode assembly. [Figure 4] 3A to 3C are diagrams showing a flow of a method for manufacturing a secondary battery according to the first embodiment. [Figure 5] FIG. 10 is a plan view for explaining a joining step. [Figure 6] FIG. 10 is a plan view for explaining an alignment step. [Figure 7] FIG. 4 is a partially enlarged view showing the state in which the electrode body is assembled to the current collecting terminal. [Figure 8] FIG. 2 is a partial plan view of a first modified example of the first embodiment. [Figure 9] FIG. 10 is a partial plan view of a second modified example of the first embodiment. [Figure 10] FIG. 10 is a partial plan view of a third modified example of the first embodiment. [Figure 11]FIG. 10 is a perspective view of a fourth modified example of the first embodiment. [Figure 12] FIG. 10 is a partial side view of a fifth modified example of the first embodiment. [Figure 13] FIG. 4 is a plan view of a secondary battery according to a second embodiment. [Figure 14] FIG. 10 is a partial side view of a modified example of the second embodiment. [Figure 15] FIG. 10 is a partial side view showing a current collecting terminal according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] A secondary battery according to one embodiment of the present invention will be described below with reference to the drawings. In the following, an example in which the secondary battery is a lithium-ion secondary battery will be described. In addition, in the following, each description and each drawing will be appropriately simplified for clarity.

[0020] First Embodiment [Overview of Secondary Battery 1] An overview of a secondary battery 1 according to this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is an exploded perspective view of the secondary battery 1. FIG. 2 is a cross-sectional view showing a schematic configuration of the secondary battery 1. In the following description, the direction parallel to the height direction of the secondary battery 1 is referred to as the Z-axis direction, the direction parallel to the winding axis direction of the electrode body 40 is referred to as the X-axis direction, and the direction parallel to the thickness direction of the electrode body 20 is referred to as the Y-axis direction. The Z-axis direction is parallel to the up-down direction, and the X-axis and Y-axis directions are perpendicular to each other and parallel to the horizontal direction. In this embodiment, the Y-axis direction corresponds to the "first direction," the X-axis direction corresponds to the "second direction," and the Z-axis direction corresponds to the "third direction."

[0021] 1 and 2, the secondary battery 1 includes a battery case 10 consisting of a case body 11 and a sealing plate 13, battery terminals PS and NS consisting of external terminals 25, 26 and current collecting terminals 27, 28 attached to the sealing plate 13, and one electrode body 40 electrically connected to the current collecting terminals 27, 28. The secondary battery 1 is a sealed secondary battery in which the one electrode body 40 and the current collecting terminals 27, 28 are housed inside the case body 11, the opening of the case body 11 is sealed with the sealing plate 13, and an electrolyte is poured into the inside of the case body 11.

[0022] [Configuration of battery case 10] As shown in FIGS. 1 and 2, a battery case 10 of this embodiment is composed of a case body 11 that is roughly rectangular and has an open top, and a sealing plate 13 that seals the opening of the case body 11. In the battery case 10 of this embodiment, the case body 11 and the sealing plate 13 are both made of aluminum, but this is not limited to this. Various metals and alloys can be used as materials for the case body 11 and the sealing plate 13. In this embodiment, the case body 11 corresponds to the "casing," and the sealing plate 13 corresponds to the "lid."

[0023] In this embodiment, the sealing plate 13 has a shape corresponding to the shape of the opening of the case body 11 and is configured to be able to seal the opening of the case body 11. Specifically, the sealing plate 13 in this embodiment is made of a flat plate member that is generally rectangular when viewed in the Z-axis direction. The sealing plate 13 has a positive battery terminal PS disposed at one end in the longitudinal direction (X-axis direction) and a negative battery terminal NS disposed at the other end in the longitudinal direction.

[0024] In this embodiment, the outer peripheral edge 13a of the sealing plate 13 and the opening edge 11a of the case body 11 are laser welded together, and the opening of the case body 11 is closed by the sealing plate 13, as will be described in detail later.

[0025] [Configuration of electrode body 40] Fig. 3 is a perspective view showing a partially developed electrode assembly 40. As shown in Fig. 3, the electrode assembly 40 is composed of a wound body obtained by stacking long strip-shaped positive electrode material 41 and negative electrode material 46 with a similarly strip-shaped separator 49 interposed therebetween, winding the stack, and then compressing the stack into a flat shape. In this embodiment, the positive electrode material 41 is aluminum foil, and the negative electrode material 46 is copper foil.

[0026] The cathode material 41 has a cathode coated portion 41a in which a cathode active material is applied to both sides, and a cathode uncoated portion 41b at one end in the X-axis direction where the cathode active material is not applied. The cathode material 41 also has a plurality of cathode tabs 42 that extend outward from the end on one side in the X-axis direction at intervals and have different lengths in the X-axis direction. The spacing between the plurality of cathode tabs 42 is set so that, after winding, a cathode tab group 51 is formed in the center of the electrode body 40 in the height direction. The length of each cathode tab 42 is set so that, after winding, the length increases from one side in the Y-axis direction to the other side.

[0027] The negative electrode material 46 has a negative electrode coated portion 46a in which a negative electrode active material is coated on both sides, and a negative electrode uncoated portion 46b in which the negative electrode active material is not coated at the end on the other side in the X axis direction. The negative electrode material 46 also has a plurality of negative electrode tabs 47 that extend outward from the end on the other side in the X axis direction at intervals and have different lengths in the X axis direction. The spacing between the plurality of negative electrode tabs 47 is set so that, after winding, a negative electrode tab group 56 is formed in the center of the electrode body 40 in the height direction. The length of each negative electrode tab 47 is set so that, after winding, the length increases from one side to the other side in the Y axis direction.

[0028] The separator 49 is disposed so as to insulate the positive electrode coated portion 41a of the positive electrode material 41 from the negative electrode coated portion 46a of the negative electrode material 46. The separator 49 can be made of an insulating material (such as a porous insulating resin material) that is permeable to ions.

[0029] The electrode body 40 has a band-shaped positive electrode tab group 51 extending from one end face in the winding axis direction (X-axis direction) and a band-shaped negative electrode tab group 56 extending from the other end face. The positive electrode tab group 51 and the negative electrode tab group 56 are formed by stacking the positive electrode tabs 42 and the negative electrode tabs 47 in layers when the positive electrode material 41 and the negative electrode material 46, on which the plurality of positive electrode tabs 42 and the negative electrode tabs 47 are formed, are wound.

[0030] The positive electrode tab group 51 of this embodiment extends along the winding axis direction from one end of the electrode assembly 40, from a portion on one side in the thickness direction (Y axis) of the electrode assembly 40 and on the central side in the height direction (Z axis) of the electrode assembly 40 when viewed from the winding axis direction (X axis direction). On the other hand, the negative electrode tab group 56 extends along the winding axis direction from a portion on one side in the thickness direction of the electrode assembly 40 and on the central side in the height direction of the electrode assembly 40 when viewed from the winding axis direction, of the other end of the electrode assembly 40. Note that the positive electrode tab group 51 and the negative electrode tab group 56 are strip-shaped with their longitudinal direction parallel to the X axis direction of the electrode assembly 40 when viewed from the thickness direction of the electrode assembly 40, and the length of the tabs 42, 47 constituting each tab group 51, 56 in the X axis direction increases from one side to the other side in the Y axis direction. Thus, the tab groups 51 and 56 extend from both ends of the electrode body 40 in the X-axis direction, which is perpendicular to the Y-axis direction that is the thickness direction of the electrode body 40.

[0031] [Configuration of the positive electrode side and negative electrode side] In this embodiment, the secondary battery 1 includes, as its positive electrode side configuration, a positive battery terminal PS consisting of a positive electrode external terminal 25 and a positive electrode current collector terminal 27, a positive electrode insulating member 29, and a positive electrode gasket 31. The secondary battery 1 also includes, as its negative electrode side configuration, a negative electrode battery terminal NS consisting of a negative electrode external terminal 26 and a negative electrode current collector terminal 28, a negative electrode insulating member 30, and a negative electrode gasket 32.

[0032] Although detailed description will be omitted, in the secondary battery 1 of this embodiment, the positive electrode external terminal 25 and the positive electrode current collector terminal 27, and the negative electrode external terminal 26 and the negative electrode current collector terminal 28 are integrated by crimping to form the respective battery terminals PS and NS. In this embodiment, the positive electrode external terminal 25 and the positive electrode current collector terminal 27 that constitute the positive electrode battery terminal PS are both made of aluminum. On the other hand, with regard to the negative electrode battery terminal NS, the negative electrode external terminal 26 is made of aluminum, and the negative electrode current collector terminal 28 is made of copper.

[0033] In this embodiment, the positive electrode external terminal 25 and the negative electrode external terminal 26 are insulated from the sealing plate 13 by a positive electrode gasket 31 and a negative electrode gasket 32. The positive electrode current collector terminal 27 and the negative electrode current collector terminal 28 are insulated from the sealing plate 13 by a positive electrode insulating member 29 and a negative electrode insulating member 30. Airtightness is maintained between each battery terminal PS, NS and the sealing plate 13 by each insulating member 29, 30 and each gasket 31, 32. In this embodiment, the insulating members 29, 30 and the gaskets 31, 32 are made of PFA resin, but the material is not limited to PFA resin. The insulating members 29, 30 and the gaskets 31, 32 may be made of any insulating material.

[0034] In this embodiment, each of the current collecting terminals 27, 28 is formed by bending a plate-like member and has a base 27a, 28a that is crimped to the corresponding external terminal 25, 26, and an electrode joint 27b, 28b that is continuous with the base 27a, 28a. That is, each of the current collecting terminals 27, 28 is a single member having the electrode joint 27b, 28b. Note that "being a single member" means that the current collecting terminals 27, 28 are made of a clad material, and does not mean that the electrode joint 27b, 28b and other portions are formed as different members and then joined together by ultrasonic welding or the like.

[0035] In this embodiment, each current collecting terminal 27, 28 has a generally rectangular shape when viewed in the Z-axis direction, and is disposed on the lower surface of the sealing plate 13 with its base 27a, 28a extending horizontally. The electrode joint 27b, 28b of each current collecting terminal 27, 28 is a generally rectangular portion when viewed in the X-axis direction that extends downward in the Z-axis direction from the end of the base 27a, 28a, and is disposed between the electrode assembly 40 and the end side wall of the case body 11. Each electrode joint 27b, 28b has a first surface Ma, Mb (a surface facing the end side wall of the case body 11) on the outer side in the X-axis direction, and a second surface M1, M2 opposite the first surface Ma, Mb. In this embodiment, the first surfaces Ma, Mb are "joint surfaces."

[0036] The downstream side in the extension direction of each tab group 51, 56 is joined to the first surfaces Ma, Mb of the electrode joints 27b, 28b of each current collecting terminal 27, 28. Each tab group 51, 56 is folded back toward the electrode assembly 40 at the end of each electrode joint 27b, 28b in the Y-axis direction while following the surface shape of the electrode joint 27b, 28b, and is stored between each electrode joint 27b, 28b and the end face of the electrode assembly 40 in the X-axis direction. Specifically, the positive electrode tab group 51 is folded back toward the electrode assembly 40 at an end 27b1 on one side in the X-axis direction of the electrode joint 27b while the upstream side in the extension direction of the joint portion A with the electrode joint 27b follows the first surface Ma, and is stored between the second surface M1 of the electrode joint 27b and the end face of the electrode assembly 40. In addition, the negative electrode tab group 56 is folded back toward the electrode body 40 at the end 28b1 on one side of the electrode joint 28b in the X-axis direction, with the upstream side of the joint portion A with the electrode joint 28b in the extension direction along the first surface Mb, and is stored between the second surface M2 of the electrode joint 28b and the end face of the electrode body 40 (see also Figure 6).

[0037] Next, a method for manufacturing the secondary battery 1 will be described. The method for manufacturing the secondary battery 1 includes a joining step and an alignment step. Each step will be described below with reference to FIGS. 4 to 7. FIG. 4 is a diagram showing the flow of the method for manufacturing the secondary battery 1. FIG. 5 is a plan view for explaining the joining step. FIG. 6 is a plan view for explaining the alignment step. FIG. 7 is a partially enlarged view showing the state in which the electrode body 40 is assembled to the negative electrode current collector terminal 28.

[0038] [Joining process] The bonding process is a process of electrically connecting the prefabricated electrode body 40 and the battery terminals PS, NS attached to the sealing plate 13. Note that the fabrication of the electrode body 40 and the attachment of the battery terminals PS, NS to the sealing plate 13 may be performed appropriately using known methods. In the bonding process, the downstream side in the extension direction of each tab group 51, 56 is bonded to the first surfaces (bonding surfaces) Ma of the current collecting terminals 27, 28 of each battery terminal PS, NS.

[0039] 5 , with the current collecting terminals 27, 28 and the electrode assembly 40 arranged at different positions in the Y-axis direction, the current collecting terminals 27, 28 and the tab groups 51, 56 of the electrode assembly 40 are arranged so that the first surfaces Ma, Mb of the electrode joints 27b, 28b face the downstream portions of the tab groups 51, 56 corresponding to the electrode joints 27b, 28b along the Y-axis direction. That is, the positive current collecting terminal 27 and the positive electrode tab group 51 of the electrode assembly 40 face the first surface Ma of the electrode joint 27b. Furthermore, the negative current collecting terminal 28 and the negative electrode tab group 56 of the electrode assembly 40 face the first surface Mb of the electrode joint 28b.

[0040] Next, each electrode joint 27b, 28b is joined to each tab group 51, 56. Specifically, the first surfaces Ma, Mb of each electrode joint 27b, 28b are brought into contact with the surfaces of each tab group 51, 56 downstream in the extension direction that face the first surfaces Ma, Mb. Next, an anvil (not shown) is pressed against the second surfaces M1, M2 of each electrode joint 27b, 28b, and a horn is pressed against the surface of each tab group 51, 56 opposite the surface facing the first surfaces Ma, Mb along the X-axis direction to apply pressure. Thereafter, ultrasonic vibrations are applied in the vertical direction by the horn. This joins each electrode joint 27b, 28b to each tab group 51, 56.

[0041] In this embodiment, the current collecting terminals 27, 28 and the electrode body 40 are disposed at different positions in the Y-axis direction, which makes it possible to perform ultrasonic bonding using a horn and anvil by utilizing the space between the positive current collecting terminal 27 and the negative current collecting terminal 28, where the electrode body 40 will ultimately be disposed.

[0042] [Alignment process] The alignment process is a process performed after the joining process. In the alignment process, the battery terminals PS, NS and the electrode body 40 are moved relative to each other along the Y-axis direction, and the tab groups 51, 56 are folded back toward the electrode body 40 at the ends 27b1, 28b1 of the electrode joints 27b, 28b in the Y-axis direction while aligning them with the surface shapes of the electrode joints 27b, 28b of the current collecting terminals 27, 28, thereby aligning the electrode body 40 with the battery terminals PS, NS.

[0043] Specifically, in this embodiment, as shown in Fig. 6, the electrode assembly 40 is moved between the positive electrode joint 27b and the negative electrode joint 28b. At this time, each tab group 51, 56 is folded back at the end portion 27b1, 28b1 so that the upstream side in the extension direction of the joining portion A with the electrode joints 27b, 28b is aligned with the first surfaces Ma, Mb and the second surfaces M1, M2, and is also folded back once between the second surfaces M1, M2 and the end surfaces of the electrode assembly 40. As a result, as shown in Fig. 7, a portion of each tab group 51, 56 is folded between both end surfaces of the electrode assembly 40 and the electrode joints 27b, 28b, and the electrode assembly 40 can be aligned between the current collecting terminals 27, 28.

[0044] In this manner, in this embodiment, two folds are performed in the alignment process: one at the end 27b1, 28b1 of the electrode junctions 27b, 28b, and one between each electrode junction 27b, 28b and the end face of the electrode body 40.

[0045] Then, the electrode body 40, which is integrated with the sealing plate 13 and each battery terminal PS, NS, is placed inside the case body 11, and laser light of a predetermined output is irradiated onto the boundary between the opening edge portion 11a of the case body 11 and the outer peripheral edge portion 13a of the sealing plate 13, welding the case body 11 and the sealing plate 13 together to close the opening of the case body 11.

[0046] As described above, in the manufacturing method of the secondary battery 1 of this embodiment, when attaching the electrode assembly 40 to the current collector terminals 27, 28 of the battery terminals PS, NS, a step for joining the components constituting the current collector terminals 27, 28 to each other is not required, and no processing for joining the current collector terminals 27, 28 to other components is required. This reduces the costs associated with the battery terminals PS, NS, and ultimately reduces the manufacturing cost of the secondary battery 1. Furthermore, because the size of the current collector terminals 27, 28 is also reduced, the dimension of the electrode assembly 40 in the X-axis direction can be increased and the volume of the electrode assembly 40 in the battery case 10 can be increased without changing the shape of the battery case 10 to increase its size. This allows a secondary battery 1 with a large battery capacity to be manufactured without changing the size of the battery case 10 (specifically, the length in the X-axis direction).

[0047] [Modification 1 of the first embodiment] Next, a secondary battery according to Modification 1 of the first embodiment will be described. In this Modification 1, as shown in FIG. 8 , in the secondary battery 1, the electrode joint portion 28b of the negative current collector terminal 28 is chamfered (chamfered portion 33). Specifically, the chamfered portion 33 is provided at a corner of the electrode joint portion 28b of the negative current collector terminal 28 that comes into contact with the negative electrode tab group 56 (in other words, at a corner of the end portion 28b1 on one side in the Y-axis direction). Although not shown, the chamfered portion 33 is also provided at the electrode joint portion 27b of the positive current collector terminal 27 that faces the positive electrode tab group 51. This makes it possible to easily prevent damage to the tab group 56(51) when the tab group 56(51) is bent so as to conform to the surface shape of the electrode joint portion 28b(27b) of the current collector terminal 28(27).

[0048] [Modification 2 of the First Embodiment] Next, a secondary battery 1 according to a second modification of the first embodiment will be described. In the second modification, as shown in FIG. 9 , the first surface Mb (bonding surface) of the electrode joint portion 28b of the negative current collector terminal 28 is inclined so that the distance to the electrode assembly 40 decreases toward one side in the Y-axis direction, and the inclined portion is formed as an inclined surface 34. In the second modification, the entire first surface Mb is the inclined surface 34. Although not shown, the first surface Ma (bonding surface) of the electrode joint portion 27b of the positive current collector terminal 27 is also inclined so that the distance to the electrode assembly 40 decreases toward one side in the Y-axis direction, and the inclined portion is formed as an inclined surface 34 (in the second modification, the entire first surface Ma is the inclined surface 34). In addition, in the alignment process, the tab group 56 (51) is folded back toward the electrode assembly 40 so as to follow the outer periphery of the electrode joint portion 28b (27b) on one side in the X-axis direction. As a result, when each tab group is folded back toward the electrode body, it is folded back along the inclined joint surface (inclined surface 34). Therefore, the bendability of the tab group 56 (51) is improved, and the tab groups 51, 56 can be stored along the inclined surface 34 of the electrode joint 28b (27b). As a result, the secondary battery 1 can increase the dimension of the electrode body 40 in the X-axis direction and increase the battery capacity. Note that in this modified example 2, the entire first surfaces Ma, Mb of each electrode joint 27b, 28b form the inclined surface 34, but only one side in the Y-axis direction of the joint portion A on the first surfaces Ma, Mb may be inclined.

[0049] [Modification 3 of the First Embodiment] Next, a secondary battery 1 according to a third modification of the first embodiment will be described. In this third modification, as shown in FIG. 10 , in the alignment step, a jig J is used to press the negative electrode tab group 56 when folding the negative electrode tab group 56 between the second surface M2 of the electrode joint portion 28b and the end face of the electrode body 40. The jig J is, for example, a rod-shaped member. A similar jig is used on the positive electrode side. Because the jig J presses the tab group 56 (51) in the Y-axis direction, the tab group 56 (51) can be efficiently accommodated between the electrode joint portion 28b (27b) and the end face of the electrode body 40.

[0050] [Fourth Modification of the First Embodiment] Next, a secondary battery 1 according to a fourth modification of the first embodiment will be described. In this fourth modification, as shown in FIG. 11 , a first portion 28bA (27bA) having a predetermined thickness and a second portion 28bB (28bB) whose outer surface is set back from the first portion 28bA (27bA) are continuous in the Z-axis direction in the electrode joint portion 28b (27b) of the current collecting terminal 28 (27). That is, the second portion 27bB (28bB) has a thinner thickness than the first portion 28bA (27bA). In the electrode joint portion 28b (27b) of the current collecting terminal 28 (27), the outer surface of the second portion 28bB (27bB) can be used as a first surface (joining surface) Mb (Ma) with the tab group 56 (51). As a result, when the tab group 56 (51) is joined to the second portion 28bB (27bB) of the electrode joint 28b (27b) of the current collecting terminal 28 (27), the dimension in the X-axis direction can be reduced by the amount of the thinner plate thickness, thereby enabling a compact configuration of the secondary battery 1. Note that by thinning only the plate thickness of the portion (second portion 27bB, 28bB) where the tab group 56 (51) is joined, deterioration of the conduction resistance at the electrode joint 28b (27b) can be minimized.

[0051] [Fifth Modification of the First Embodiment] Next, a secondary battery 1 according to a fifth modification of the first embodiment will be described. In the secondary battery 1 according to the first embodiment, the electrode body 40 is aligned between the current collecting terminals 27, 28. For example, disturbances such as vehicle vibrations may cause the electrode body 40 to shift in position in the Y-axis direction or rotate around an axis along the X-axis direction. Therefore, in the fifth modification, as shown in FIG. 12 , the current collecting terminals 28 (27) and the electrode body 40 are covered with a box-shaped insulating film F with an open top, and the upper end of the insulating film F is welded to the underside of the sealing plate 13. This allows the insulating film F to prevent the electrode body 40 from shifting in position in the Y-axis direction or rotating around the axis.

[0052] Second Embodiment Next, a second embodiment will be described. Differences from the first embodiment will be mainly described below, and similarities to the first embodiment will not be described. In the second embodiment, as shown in FIG. 13 , two electrode assemblies 40 are joined to current collecting terminals 27 and 28. In this case, during the joining process, the length of the tab group 51 and 56 of the electrode assembly 40 that is closer to the electrode joints 27b and 28b of the two electrode assemblies 40 as viewed in the Z-axis direction is set to be shorter than the tab group 51 and 56 of the other electrode assembly 40. This allows the tip positions of the tab groups 51 and 56 of the two electrode assemblies 40 to be aligned at the joint area A. In this state, the two electrode bodies 40, 40 can be assembled to the collector terminals 27, 28 by joining each tab group 51, 56 to the first surface (joining surface) Ma, Mb of each electrode joint portion 27b, 28b, and aligning the electrode body 40 between the collector terminals 27, 28 while appropriately folding back each tab group 51, 56.

[0053] [Modification of the second embodiment] Next, a modified example of the second embodiment will be described. In this modified example, as shown in Fig. 14, the lengths of the tab groups 51, 56 of the two electrode assemblies 40, 40 are set to be the same. In this way, during the joining process, one end 51a, 56a of the tab group 51, 56 of the electrode assembly 40 arranged closer to the electrode joint portions 27b, 28b as viewed in the Z-axis direction protrudes from the joining site A. However, in this case, by appropriately cutting the one end 51a, 56a, which is the protruding portion, the tip ends of the tab groups 51, 56 of the two electrode assemblies 40, 40 can be easily aligned.

[0054] Third Embodiment Next, a third embodiment will be described. The following mainly describes differences from the first and second embodiments, and omits a description of similarities between the first and second embodiments. In the third embodiment, as shown in FIG. 15 , four electrode bodies 40 are joined to the current collecting terminals 27, 28. In this case, in the joining step, two electrode bodies 40 are arranged on either side of the current collecting terminals 27, 28 in the Y-axis direction, and in the positioning step, the four electrode bodies 40 are moved relative to one another. That is, when viewed in the Z-axis direction, the two electrode bodies 40 are inserted between the current collecting terminals 27, 28 from both sides. In this manner, the four electrode bodies 40 can be assembled to the current collecting terminals 27, 28.

[0055] [Another embodiment] [1] In the above embodiment, the tab groups 51, 56 are folded back once between the second surfaces M1, M2 of the electrode joints 27b, 28b and the end surface of the electrode body 40, but the present invention is not limited to this. The tab groups 51, 56 may be folded back two or more times between the second surfaces M1, M2 of the electrode joints 27b, 28b and the end surface of the electrode body 40.

[0056] [2] In the above embodiment, the tab groups 51, 56 extend from a portion of each end face of the electrode assembly 40 that is located on one side in the thickness direction (Y-axis direction) of the electrode assembly 40 when viewed from the winding axis direction (X-axis direction). However, the present invention is not limited to this. For example, the tab groups 51, 56 may extend from a central portion of each end face of the electrode assembly 40 in the thickness direction (Y-axis direction) of the electrode assembly 40 when viewed from the winding axis direction (X-axis direction).

[0057] [3] In the above embodiment, the secondary battery 1 is described as having one, two, or four electrode bodies 40, but the present invention is not limited to such an embodiment. The number of electrode bodies may be three, five or more, or four or more. In this case, by stacking multiple tab groups according to the number of electrode bodies and joining them to one electrode joint, the number of electrode bodies can be increased while suppressing an increase in the number of parts.

[0058] [4] In the above embodiment, the positive electrode tab group 51 and the negative electrode tab group 56 of each electrode assembly 40 are positioned at the same position in the Z-axis direction, but this is not limited to this. The positive electrode tab group and the negative electrode tab group of each electrode assembly may be positioned above or below the center in the Z-axis direction. The positive electrode tab group and the negative electrode tab group of each electrode assembly may be positioned at different positions in the Z-axis direction.

[0059] [5] In the above embodiment, the electrode assembly 40 is a wound body, but the present invention is not limited to this. The electrode assembly 40 is not particularly limited as long as it has a structure including a positive electrode tab group and a negative electrode tab group, and various structures used in general sealed secondary batteries can be employed.

[0060] The configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradiction arises. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Explanation of symbols]

[0061] 1: Secondary battery 11: Case body (housing) 13: Sealing plate (lid body) 27,28: Current collector terminal 27b, 28b: Electrode joint 27b1,28b1: End 33: Chamfered part 34: Inclined surface 40: Electrode body 41: Cathode material 42: Positive electrode tab 46: Anode material 47: Negative electrode tab 51: Positive electrode tab group 56: Negative electrode tab group Ma,Mb: Joint surface PS: Positive battery terminal (battery terminal) NS: Negative battery terminal (battery terminal)

Claims

1. A method for manufacturing a secondary battery comprising: a housing having an opening; a lid attached to the opening of the housing; a flat electrode assembly formed by laminating a positive electrode material and a negative electrode material with a separator interposed therebetween; and a positive electrode battery terminal and a negative electrode battery terminal each attached to the lid, the electrode body has one end surface in a second direction orthogonal to a first direction that is a thickness direction of the electrode body, from which a band-shaped positive electrode tab group formed by stacking tabs of the positive electrode material extends, and the other end surface in the second direction has a band-shaped negative electrode tab group formed by stacking tabs of the negative electrode material extends, the positive battery terminal and the negative battery terminal have current collecting terminals including plate-shaped electrode joints disposed along the end faces of the electrode body between the housing and each end face of the electrode body in the second direction, the electrode joint portion has a surface facing the housing as a joint surface, a joining process in which a downstream side of the extension direction of the positive electrode tab group is joined to the joining surface of the current collector terminal of the positive battery terminal, and a downstream side of the extension direction of the negative electrode tab group is joined to the joining surface of the current collector terminal of the negative battery terminal; and an alignment step of, after the joining step, moving the positive battery terminal and the negative battery terminal relative to the electrode body along the first direction, folding back the ends of the electrode joint portions in the first direction toward the electrode body while aligning the positive electrode tab group and the negative electrode tab group with the surface shapes of the electrode joint portions of the current collector terminals, and aligning the electrode body between the positive electrode battery terminal and the negative electrode battery terminal.

2. 2. The method for manufacturing a secondary battery according to claim 1, wherein in the alignment step, at least a portion of the positive electrode tab group and the negative electrode tab group are stored in a state where they are folded back once or multiple times between the electrode joint portion and the end face of the electrode body in the second direction.

3. The method for manufacturing a secondary battery according to claim 1 , wherein the electrode joint portion is chamfered.

4. The method for manufacturing a secondary battery according to claim 1 , wherein the joining surface of the electrode joining portion is inclined so that the distance to the electrode body decreases toward one side in the first direction.

5. A secondary battery comprising: a housing having an opening; a lid attached to the opening of the housing; a flat electrode body formed by laminating a positive electrode material and a negative electrode material with a separator interposed therebetween; and a positive electrode battery terminal and a negative electrode battery terminal each attached to the lid, The electrode body is It is housed inside the housing, a band-shaped positive electrode tab group formed by stacking tabs of the positive electrode material extends from one end face in a second direction orthogonal to a first direction that is the thickness direction of the electrode body, and a band-shaped negative electrode tab group formed by stacking tabs of the negative electrode material extends from the other end face, the positive battery terminal and the negative battery terminal have current collecting terminals including electrode junctions; the electrode joint portion is a plate-like member disposed along the end surface of the electrode body between each end surface of the electrode body in the second direction and the housing, and a surface facing the housing is a joint surface; the positive electrode tab group and the negative electrode tab group are folded back toward the electrode body at the end of the electrode junction in the first direction while following the surface shape of the electrode junction of each of the current collector terminals, with the downstream side in the extension direction joined to the joining surface of the current collector terminal of each of the positive electrode battery terminal and the negative electrode battery terminal, and are stored between each of the electrode junctions and the end face of the electrode body in the second direction.

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