Battery pack and bonding method

Abstract

An object of the present invention is to make the thickness of the joining portion thinner even if the gap space between the electrode sheets is narrow, wherein the first electrode sheet has a first electrode surface facing the second electrode sheet side, the first electrode surface has a portion joined to the second electrode sheet and a portion not joined to the second electrode sheet, and the portion of the first electrode surface not joined to the second electrode sheet is joined to a first conductive component.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a battery pack and a bonding method. Background Art

[0002] Patent Document 1 discloses a battery pack. The battery pack of Patent Document 1 includes a first cell and a second cell overlapping the first cell. The first cell includes a first battery body and a first electrode sheet protruding and extending from the first battery body. The second cell includes a second battery body and a second electrode sheet protruding and extending from the second battery body and joined to the first electrode sheet.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2016 / 020999 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In the battery pack of patent document 1, when trying to join other components (components other than the first electrode sheet and the second electrode sheet) to the first electrode sheet, the following situation occurs: the first electrode sheet, the second electrode sheet and the other components overlap into three layers, and the thickness of the joint between the first electrode sheet and the second electrode sheet is relatively thick. In a battery pack having a plurality of single cells, the gap space between two adjacent electrode sheets in the direction in which the plurality of single cells overlap is relatively narrow, so if the thickness of the joint between the first electrode sheet and the second electrode sheet is relatively thick, an undesirable situation will occur. For example, an undesirable situation such as a narrow working space for the joining operation will occur. Therefore, this specification provides a technology that can make the thickness of the joint between the first electrode sheet and the second electrode sheet thinner.

[0008] Solutions for solving problems

[0009] Alternatively, the battery pack disclosed in this specification includes a first single cell and a second single cell overlapping the first single cell. Alternatively, the first single cell includes a first battery body and a first electrode sheet protruding from the first battery body. Alternatively, the second single cell includes a second battery body and a second electrode sheet protruding from the second battery body and joined to the first electrode sheet. Alternatively, the first electrode sheet includes a first electrode surface facing the second electrode sheet side. Alternatively, the first electrode surface includes a portion to which the second electrode sheet is joined and a portion to which the second electrode sheet is not joined. Alternatively, a first conductive member is joined to a portion of the first electrode surface to which the second electrode sheet is not joined.

[0010] According to this structure, the first conductive member is bonded to the portion of the first electrode surface of the first electrode sheet to which the second electrode sheet is not bonded, so that the first electrode sheet, the second electrode sheet, and the first conductive member do not overlap into three layers, and the thickness of the bonded portion between the first electrode sheet and the second electrode sheet can be made thinner. Therefore, even if the gap between the first electrode sheet and the second electrode sheet is narrow, the thickness of the bonded portion is thin, so that, for example, a working space can be ensured when performing a bonding operation.

[0011] Alternatively, the second electrode sheet may be joined to the top end of the first electrode sheet in the direction in which the first electrode sheet protrudes. According to this structure, the joining portion between the first electrode sheet and the second electrode sheet is away from the first cell and the second cell, so that even if the first cell and the second cell are separated in the direction in which they overlap each other, the influence thereof can be suppressed from reaching the joining portion, and the second electrode sheet can be suppressed from peeling off from the first electrode sheet.

[0012] Alternatively, the first conductive member may be arranged next to the second electrode sheet in a direction perpendicular to the direction in which the first electrode sheet protrudes and in a direction perpendicular to the direction in which the first electrode sheet and the second electrode sheet overlap. According to this structure, when the second electrode sheet and the first conductive member are joined to the first electrode sheet, interference between the first battery body and the second battery body in the joining operation can be suppressed, and the joining operation can be performed smoothly.

[0013] Alternatively, the first conductive member extends in the direction in which the first electrode sheet protrudes, one end of the first conductive member is joined to the first electrode sheet, and the other end of the first conductive member protrudes from the first electrode sheet. According to this structure, the other end of the first conductive member is arranged at a position away from the first battery body. Therefore, it is easy to join other members (for example, the second conductive member) to the other end of the first conductive member.

[0014] Alternatively, the first conductive member may include a first conductive surface facing the first electrode sheet. Alternatively, the first conductive surface may include a portion joined to the first electrode sheet and a portion not joined to the first electrode sheet. Alternatively, a second conductive member may be joined to the portion of the first conductive surface not joined to the first electrode sheet. According to this structure, the first electrode sheet, the first conductive member, and the second conductive member will not overlap into three layers, and the thickness of the joined portion can be made thinner.

[0015] The first electrode sheet and the second electrode sheet may be joined by laser welding. According to this structure, the first electrode sheet and the second electrode sheet can be firmly joined.

[0016] Alternatively, the first electrode sheet and the second electrode sheet are laser welded at a position on the surface of the first electrode closer to the top side than the central portion. According to this structure, even when it is difficult to ensure a working space during the joining operation, interference between the first battery body and the second battery body in the joining operation can be suppressed, and the joining operation can be smoothly performed.

[0017] The first electrode sheet and the second electrode sheet may be joined by ultrasonic welding. According to this configuration, the thickness of the joint portion between the first electrode sheet and the second electrode sheet can be made thinner than when joined by brazing or the like.

[0018] Alternatively, the first electrode sheet and the first conductive member are joined by laser welding. According to this structure, the first electrode sheet and the first conductive member can be firmly joined. In addition, when the first electrode sheet and the second electrode sheet are also joined by laser welding, the joining operation can be performed under the same welding conditions, thereby simplifying the joining operation.

[0019] The first conductive member and the second conductive member may be joined by ultrasonic welding. According to this configuration, the thickness of the joined portion can be made thinner than when joining by soldering or the like.

[0020] Alternatively, the joining method disclosed in this specification is a joining method for a battery pack having a first single cell and a second single cell overlapping the first single cell. Alternatively, the first single cell has a first battery body and a first electrode sheet protruding from the first battery body. Alternatively, the second single cell has a second battery body and a second electrode sheet protruding from the second battery body. Alternatively, the first electrode sheet has a first electrode surface facing the second electrode sheet side. Alternatively, the joining method for a battery pack includes: a first step of joining the second electrode sheet to a portion of the first electrode surface; and a second step of joining the first conductive member to a portion of the first electrode surface to which the second electrode sheet is not joined.

[0021] According to this structure, the first electrode sheet, the second electrode sheet, and the first conductive member are not overlapped in three layers, and the thickness of the bonding portion between the first electrode sheet and the second electrode sheet can be made thin.

[0022] Alternatively, in the first step, the first electrode sheet and the second electrode sheet are joined by laser welding by irradiating laser along the first direction. Alternatively, in the second step, the first electrode sheet and the first conductive member are joined by laser welding by irradiating laser along the first direction which is the same as that in the first step.

[0023] According to this configuration, since the laser light is irradiated from the same direction in the first step and the second step, the second electrode sheet and the first conductive member can be bonded to the first electrode sheet at once. Therefore, the bonding operation can be simplified.

[0024] Alternatively, in the first step and / or the second step, laser light may be irradiated to multiple locations. According to this structure, the first electrode sheet and the second electrode sheet can be firmly joined. And / or, the first electrode sheet and the first conductive member can be firmly joined. In addition, when laser light is irradiated to multiple locations, the joining operation may be more complicated sometimes, but by irradiating the laser light from the same direction in the first step and the second step, the joining operation can be simplified even when laser light is irradiated to multiple locations. A simple joining operation can be used to perform a firm joining. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a perspective view schematically showing a battery pack according to an embodiment.

[0026] Figure 2 yes Figure 1 II-II sectional view.

[0027] Figure 3 It is a perspective view schematically showing a part of the battery pack according to the embodiment.

[0028] Figure 4 yes Figure 3 IV-IV cross-sectional view.

[0029] Figure 5 Yes Figure 3 The image is flipped upside down and left to right.

[0030] Figure 6 yes Figure 3 VI-VI section view. DETAILED DESCRIPTION

[0031] The battery pack of the embodiment will be described with reference to the accompanying drawings. Figure 1 As shown, the battery pack 1 of the embodiment includes a plurality of cells 2 . Figure 1The battery pack 1 shown is connected to a motor of an electric vehicle (electric vehicle, hybrid vehicle, etc.), for example. Each single cell 2 is a secondary battery that can be charged and discharged. Each single cell 2 is, for example, a lithium-ion battery. The battery pack 1 includes a first single cell 10 and a second single cell 20. The first single cell 10 and the second single cell 20 are arranged overlapping in the up-down direction. The following description focuses on the first single cell 10 and the second single cell 20. One of the multiple single cells 2 is set as the first single cell 10, and the other is set as the second single cell 20. In addition, the following description is based on the up-down, front-back, and left-right directions shown in the drawings. In addition, the up-down, front-back, and left-right directions shown in the drawings are directions used for the convenience of description.

[0032] (First Cell 10)

[0033] First, the first cell 10 is described. The first cell 10 is, for example, the cell 2 at the bottom of the plurality of cells 2 constituting the battery pack 1. The first cell 10 includes a first battery body 11, a first positive electrode sheet 12 (an example of a first electrode sheet), and a first negative electrode sheet 13. The first battery body 11 includes a housing 110, a diaphragm, a positive electrode plate, and a negative electrode plate (none of which is shown in the figure) arranged in the housing 110. In addition, a liquid or solid electrolyte is contained in the housing 110. In the housing 110, ions move between the positive electrode plate and the negative electrode plate via the diaphragm. Thus, charging or discharging is performed in the first cell 10. The thickness of the housing 110 in the up-down direction is very thin compared to the length of the housing 110 in the front-back direction and the length in the left-right direction. For example, the thickness of the housing 110 in the up-down direction is less than 1 / 10 of the length of the housing 110 in the front-back direction and the length in the left-right direction. In addition, the structure in the housing 110 is well known, so a detailed description is omitted.

[0034] The first positive electrode sheet 12 of the first cell 10 is described. The first positive electrode sheet 12 is made of, for example, aluminum (Al). Figure 2As shown, the first positive electrode sheet 12 protrudes from the first battery body 11 to the front side and extends to the front side. The first positive electrode sheet 12 is fixed to the shell 110 of the first battery body 11. The first positive electrode sheet 12 includes a base end portion 31, a top end portion 32 and a central portion 33. The base end portion 31 is fixed to the shell 110 of the first battery body 11. The base end portion 31 is electrically connected to the positive electrode plate arranged in the shell 110. The top end portion 32 is located at a position closer to the front side than the base end portion 31. The central portion 33 is located between the base end portion 31 and the top end portion 32 in the front-to-back direction. The first positive electrode sheet 12 includes an upper surface 34 and a lower surface 35. The upper surface 34 faces the second single cell 20 side (upper side). The lower surface 35 faces the side opposite to the second single cell 20 (lower side). In addition, the first positive electrode sheet 12 includes a first bent portion 36 and a second bent portion 37. The first positive electrode sheet 12 is bent at the first bent portion 36 and the second bent portion 37. The first bent portion 36 is located at a position on the rear side and lower side of the central portion 33 of the first positive electrode sheet 12. The first positive electrode sheet 12 is bent upward at the first bent portion 36. The second bent portion 37 is located at a position on the front side and upper side of the central portion 33 of the first positive electrode sheet 12. The first positive electrode sheet 12 is bent forward at the second bent portion 37.

[0035] like Figure 3 As shown, the first positive electrode sheet 12 includes a first electrode surface 41. The first electrode surface 41 is formed on a portion of the upper surface 34 of the first positive electrode sheet 12. The first electrode surface 41 is located on the front side of the first positive electrode sheet 12 relative to the second bent portion 37. The first electrode surface 41 faces the second battery cell 20 side (upper side). The first electrode surface 41 faces the second negative electrode sheet 23 side of the second battery cell 20. The first electrode surface 41 extends in the front-to-back direction and the left-to-right direction.

[0036] like Figure 4 As shown, the first electrode surface 41 includes a first portion 43 and a second portion 44. The first portion 43 and the second portion 44 are arranged in the left-right direction. The first portion 43 is located on the left side of the second portion 44 ( Figure 1 The first portion 43 faces the second negative electrode sheet 23 of the second battery cell 20. The second negative electrode sheet 23 is joined to the first portion 43. The second portion 44 is located to the right of the first portion 43 (towards the side of the first negative electrode sheet 13 shown in FIG. 1 ). Figure 1 The second portion 44 is a portion of the first electrode surface 41 other than the first portion 43. The second portion 44 does not face the second negative electrode sheet 23 of the second cell 20. The second portion 44 is not joined to the second negative electrode sheet 23. The second portion 44 is exposed from the second negative electrode sheet 23. The second portion 44 faces the first conductive member 70 described later. The first conductive member 70 is joined to the second portion 44.

[0037] like Figure 1As shown, the first negative electrode sheet 13 of the first cell 10 protrudes from the first battery body 11 to the front side and extends to the front side. The structure of the first negative electrode sheet 13 of the first cell 10 is the same as the structure of the second negative electrode sheet 23 of the second cell 20 described later. More specifically, the structure of the first negative electrode sheet 13 of the first cell 10 is the same as the structure of the second negative electrode sheet 23 when the bending direction of the first bent portion 56 of the second negative electrode sheet 23 is set to the opposite side after the second cell 20 described later is turned upside down and left and right. Therefore, the detailed description of the structure of the first negative electrode sheet 13 of the first cell 10 is omitted. The first negative electrode sheet 13 of the first cell 10 is not connected to the positive electrode sheet or negative electrode sheet of other cells, but is electrically connected to a device (for example, a motor of an electric vehicle, etc.) that uses the power of the battery pack 1.

[0038] (Second Cell 20)

[0039] Next, the second cell 20 is described. The second cell 20 is stacked on the upper side of the first cell 10. The second cell 20 includes a second battery body 21, a second positive electrode sheet 22, and a second negative electrode sheet 23 (an example of a second electrode sheet). The structure of the second battery body 21 is the same as the structure of the first battery body 11 of the first cell 10 described above, so a detailed description is omitted.

[0040] The second negative electrode sheet 23 of the second cell 20 is described. The second negative electrode sheet 23 is made of, for example, copper (Cu). Figure 2 As shown, the second negative electrode sheet 23 protrudes from the second battery body 21 to the front side and extends to the front side. The second negative electrode sheet 23 is fixed to the shell 210 of the second battery body 21. The second negative electrode sheet 23 includes a base end portion 51, a top end portion 52 and a central portion 53. The base end portion 51 is fixed to the shell 210 of the second battery body 21. The base end portion 51 is electrically connected to the negative electrode plate arranged in the shell 210. The top end portion 52 is located at a position closer to the front side than the base end portion 51. The central portion 53 is located between the base end portion 51 and the top end portion 52 in the front-to-back direction. The second negative electrode sheet 23 includes an upper surface 54 and a lower surface 55. The upper surface 54 faces the side opposite to the first single cell 10 side (upper side). The lower surface 55 faces the first single cell 10 side (lower side). In addition, the second negative electrode sheet 23 includes a first bent portion 56 and a second bent portion 57. The second negative electrode sheet 23 is bent at the first bent portion 56 and the second bent portion 57. The first bent portion 56 is located at the rear side and the upper side of the center portion 53 of the second negative electrode sheet 23. The second negative electrode sheet 23 is bent downward at the first bent portion 56. The second bent portion 57 is located at the front side and the lower side of the center portion 53 of the second negative electrode sheet 23. The second negative electrode sheet 23 is bent forward at the second bent portion 57.

[0041] like Figure 3 and Figure 4 As shown, the second negative electrode sheet 23 includes a second electrode surface 62. The second electrode surface 62 is formed on a portion of the lower surface 55 of the second negative electrode sheet 23. The second electrode surface 62 is located at a position of the second negative electrode sheet 23 that is closer to the front side than the second bent portion 57. The second electrode surface 62 extends in the front-to-back direction and the left-to-right direction. The second electrode surface 62 faces the first battery cell 10 side (lower side). The second electrode surface 62 faces the first positive electrode sheet 12 side of the first battery cell 10. The second electrode surface 62 faces the first portion 43 of the first electrode surface 41 of the first positive electrode sheet 12. The second electrode surface 62 is joined to the first portion 43 of the first electrode surface 41. The top end portion 52 of the second negative electrode sheet 23 is joined to the top end portion 32 of the first positive electrode sheet 12.

[0042] The second negative electrode sheet 23 and the first positive electrode sheet 12 are joined by laser welding, for example. Figure 5 As shown, the first positive electrode sheet 12 and the second negative electrode sheet 23 are joined by irradiating the lower surface 35 of the first positive electrode sheet 12 with laser light L. By irradiating the laser light L, a plurality of laser welded portions 91 are formed on the lower surface 35 of the first positive electrode sheet 12 .

[0043] like Figure 1 As shown, the second positive electrode sheet 22 of the second cell 20 protrudes from the second battery body 21 to the front side and extends to the front side. The structure of the second positive electrode sheet 22 of the second cell 20 is the same as the structure of the first positive electrode sheet 12 of the first cell 10 described above. More specifically, the structure of the second positive electrode sheet 22 of the second cell 20 is the same as the structure of the first positive electrode sheet 12 in the case where the bending direction of the first bent portion 36 of the first positive electrode sheet 12 is set to the opposite side after the first cell 10 is turned upside down and left and right. Therefore, the detailed description of the structure of the second positive electrode sheet 22 of the second cell 20 is omitted.

[0044] (First Conductive Member 70)

[0045] Next, the first conductive member 70 will be described. Figures 3 to 6 As shown, the first conductive member 70 extends in the front-to-back direction. The first conductive member 70 is a metal plate-shaped member. The first conductive member 70 is made of, for example, copper (Cu). The first conductive member 70 is arranged next to the second negative electrode sheet 23 of the second cell 20 in the left-right direction. The second negative electrode sheet 23 and the first conductive member 70 are arranged in the left-to-right direction. The first conductive member 70 includes a base end portion 75 (an example of one end) and a top end portion 76 (an example of the other end). The base end portion 75 is joined to the first positive electrode sheet 12 of the first cell 10. The top end portion 76 is located at a position further forward than the base end portion 75. The top end portion 76 is not joined to the first positive electrode sheet 12 of the first cell 10. The top end portion 76 protrudes from the first positive electrode sheet 12 to the front side in the front-to-back direction.

[0046] The first conductive member 70 includes a first conductive surface 71. The first conductive surface 71 faces the first positive electrode sheet 12 side (lower side) of the first cell 10. The first conductive surface 71 extends in the front-to-back direction and the left-to-right direction. The first conductive surface 71 includes a first portion 73 and a second portion 74. The first portion 73 and the second portion 74 are arranged in the front-to-back direction. The first portion 73 is located at a rearward position than the second portion 74. The first portion 73 faces the second portion 44 of the first electrode surface 41 of the first positive electrode sheet 12. The first positive electrode sheet 12 is joined to the first portion 73.

[0047] The first conductive member 70 and the first positive electrode sheet 12 are joined by, for example, laser welding. Figure 5 As shown, the first positive electrode sheet 12 and the first conductive member 70 are bonded to each other by irradiating the lower surface 35 of the first positive electrode sheet 12 with laser light L. The irradiation with laser light L forms a plurality of laser welded portions 92 on the lower surface 35 of the first positive electrode sheet 12 .

[0048] like Figures 3 to 6 As shown, the second portion 74 of the first conductive surface 71 of the first conductive member 70 is located at a position forward of the first portion 73. The second portion 74 is a portion of the first conductive surface 71 other than the first portion 73. The second portion 74 does not face the first positive electrode sheet 12 of the first cell 10. The first positive electrode sheet 12 is not joined to the second portion 74. The second portion 74 is exposed from the first positive electrode sheet 12. The second conductive member 80 is joined to the second portion 74.

[0049] (Second Conductive Member 80)

[0050] The second conductive member 80 is described. The second conductive member 80 is, for example, a metal wire for measuring the voltage of the first cell 10. The second conductive member 80 may also be covered by an insulator. In other examples, the second conductive member 80 may also be a metal plate-shaped member. The second conductive member 80 is, for example, made of copper (Cu). The second conductive member 80 is joined to the first conductive member 70 by, for example, ultrasonic welding or soldering. Ultrasonic welding is a joining method in which components are pressed and ultrasonic vibrations are applied while the components are in contact with each other, thereby welding the components. One end of the second conductive member 80 is joined to the second portion 74 of the first conductive surface 71 of the first conductive member 70. The other end of the second conductive member 80 is, for example, connected to a device (not shown) for measuring the voltage of the battery pack 1 and the voltage of each cell 2 (for example, the first cell 10) constituting the battery pack 1.

[0051] (Joining method)

[0052] Next, a method for joining the battery pack 1 is described. In the method for joining the battery pack 1, Figure 1 As shown in FIG. 1 , the first cell 10 and the second cell 20 are stacked in the vertical direction. Figures 1 to 5 As shown, the first positive electrode sheet 12 of the first cell 10 and the second negative electrode sheet 23 of the second cell 20 overlap in the vertical direction, and the first electrode surface 41 of the first positive electrode sheet 12 and the second electrode surface 62 of the second negative electrode sheet 23 are in contact with each other in a state of facing each other. The second electrode surface 62 of the second negative electrode sheet 23 is in contact with the first portion 43 of the first electrode surface 41 of the first positive electrode sheet 12.

[0053] Next, the first conductive member 70 is overlapped on the first electrode surface 41 side of the first positive electrode sheet 12. At this time, the first conductive member 70 is overlapped on the portion where the second negative electrode sheet 23 is not overlapped. That is, the first conductive member 70 is overlapped on the second portion 44 of the first electrode surface 41 of the first positive electrode sheet 12. The first conductive surface 71 of the first conductive member 70 is in contact with the second portion 44 of the first electrode surface 41.

[0054] Then, if Figure 5 As shown in FIG. 1 , in a state where the first positive electrode sheet 12 and the second negative electrode sheet 23 overlap in the vertical direction, the surface (lower surface 35) of the first positive electrode sheet 12 on the side opposite to the first electrode surface 41 is irradiated with laser light L (first step). The laser light L is irradiated in the direction from the lower side to the upper side. In the first step, the laser light L is irradiated on the surface (lower surface 35) on the side opposite to the first electrode surface 41 at a position closer to the tip side than the central portion 411 in the front-back direction of the first electrode surface 41. That is, when the length of the portion of the first positive electrode sheet 12 closer to the tip side than the second curved portion 37 is set to R, the laser light L is irradiated at a position R / 2 from the second curved portion 37 or a position closer to the tip side than the position R / 2. In the first step, the laser light L is irradiated in the left-right direction. In addition, the laser light L is irradiated at a predetermined interval (for example, an interval of 0.1 mm) at a plurality of locations in the front-back direction. In the first step, the first positive electrode sheet 12 is irradiated with laser light L, thereby joining the first positive electrode sheet 12 and the second negative electrode sheet 23 by laser welding.

[0055] Next, the second conductive member 80 is joined to the first conductive member 70. More specifically, the second conductive member 80 is joined to the second portion 74 of the first conductive surface 71 of the first conductive member 70. For example, the second conductive member 80 is joined to the first conductive member 70 by ultrasonic welding. Alternatively, soldering may be used for joining.

[0056] Next, in a state where the first positive electrode sheet 12 and the first conductive member 70 overlap in the vertical direction, the surface (lower surface 35) of the first positive electrode sheet 12 on the side opposite to the first electrode surface 41 is irradiated with laser light L (second step). In the second step, the laser light L is irradiated from the same direction as in the first step described above. That is, the laser light L is irradiated in a direction from the lower side to the upper side. In addition, in the second step, when the length of the portion of the first positive electrode sheet 12 closer to the top end than the second curved portion 37 is set to R, the laser light L is irradiated to the surface (lower surface 35) on the side opposite to the first electrode surface 41 at a position R / 2 from the second curved portion 37 or a position closer to the top end than the position R / 2. In the second step, the laser light L is irradiated in the front-back direction. In addition, the laser light L is irradiated to a plurality of locations in the left-right direction at a predetermined interval (for example, an interval of 0.1 mm). In the second step, the first positive electrode sheet 12 is irradiated with laser light L, thereby joining the first positive electrode sheet 12 and the first conductive member 70 by laser welding.

[0057] The battery pack 1 of the embodiment has been described above. As can be seen from the above description, in the battery pack 1 of the embodiment, the first single cell 10 includes the first battery body 11 and the first positive electrode sheet 12 protruding from the first battery body 11. The second single cell 20 includes the second battery body 21 and the second negative electrode sheet 23 protruding from the second battery body 21 and joined to the first positive electrode sheet 12. The first positive electrode sheet 12 includes the first electrode surface 41 facing the second negative electrode sheet 23 side. The first electrode surface 41 includes the first portion 43 to which the second negative electrode sheet 23 is joined and the second portion 44 to which the second negative electrode sheet 23 is not joined. The first conductive member 70 is joined to the second portion 44 to which the second negative electrode sheet 23 is not joined in the first electrode surface 41.

[0058] According to this structure, the first conductive component 70 is joined to a portion of the first electrode surface 41 of the first positive electrode sheet 12 to which the second negative electrode sheet 23 is not joined. Therefore, the first positive electrode sheet 12, the second negative electrode sheet 23 and the first conductive component 70 do not overlap into three layers in the up and down directions, and the thickness of the joining portion between the first positive electrode sheet 12 and the second negative electrode sheet 23 can be made thinner.

[0059] In the battery pack 1, the thickness in the vertical direction when the first single cell 10 and the second single cell 20 are stacked is very thin, and the gap between the first positive electrode sheet 12 and the second negative electrode sheet 23 is narrow. According to the above structure, the thickness of the joint portion between the first positive electrode sheet 12 and the second negative electrode sheet 23 is thin, so that, for example, a working space can be ensured during the joint operation. In the battery pack 1, it is particularly effective to make the thickness of the joint portion between the first positive electrode sheet 12 and the second negative electrode sheet 23 thin.

[0060] In the above-mentioned battery pack 1, the second negative electrode sheet 23 is joined to the top end portion 32 of the first positive electrode sheet 12 in the direction in which the first positive electrode sheet 12 protrudes (front-back direction). According to this structure, the joint portion between the first positive electrode sheet 12 and the second negative electrode sheet 23 is away from the first cell 10 and the second cell 20. Therefore, even if the first cell 10 and the second cell 20 are separated in the direction in which they overlap each other (up and down direction), it is possible to suppress the influence of the joint portion between the first positive electrode sheet 12 and the second negative electrode sheet 23. Therefore, it is possible to suppress the second negative electrode sheet 23 from peeling off from the first positive electrode sheet 12.

[0061] In the above-mentioned battery pack 1, the first conductive member 70 is arranged next to the second negative electrode sheet 23 in a direction perpendicular to the direction in which the first positive electrode sheet 12 protrudes (front-back direction) and in a direction perpendicular to the direction in which the first positive electrode sheet 12 and the second negative electrode sheet 23 overlap (up-down direction) (i.e., left-right direction). According to this structure, when the second negative electrode sheet 23 and the first conductive member 70 are joined to the first positive electrode sheet 12, it is possible to suppress the first battery body 11 and the second battery body 21 from interfering with the joining operation, and the joining operation can be smoothly performed.

[0062] In the above-mentioned battery pack 1, the first conductive member 70 extends in the direction (front-rear direction) in which the first positive electrode sheet 12 protrudes, the base end portion 75 of the first conductive member 70 is joined to the first positive electrode sheet 12, and the top end portion 76 of the first conductive member 70 protrudes from the first positive electrode sheet 12. According to this structure, the top end portion 76 of the first conductive member 70 is arranged at a position away from the first battery body 11. Therefore, other members (for example, the second conductive member 80) can be easily joined to the top end portion 76 of the first conductive member 70.

[0063] The first conductive member 70 includes a first conductive surface 71 facing the first positive electrode sheet 12. The first conductive surface 71 includes a first portion 73 joined to the first positive electrode sheet 12 and a second portion 74 not joined to the first positive electrode sheet 12. The second conductive member 80 is joined to the second portion 74 of the first conductive surface 71 not joined to the first positive electrode sheet 12. According to this structure, the first positive electrode sheet 12, the first conductive member 70, and the second conductive member 80 are not overlapped in three layers in the vertical direction, and the thickness of the joined portion can be made thin.

[0064] In the above-described assembled battery 1, the first positive electrode sheet 12 and the second negative electrode sheet 23 are joined by laser welding. According to this structure, the first positive electrode sheet 12 and the second negative electrode sheet 23 can be firmly joined.

[0065] In the above-mentioned battery pack 1, the first positive electrode sheet 12 and the second negative electrode sheet 23 are joined by laser welding at a position closer to the top side than the central portion 411 of the first electrode surface 41. According to this structure, even in the case where it is difficult to ensure a working space during the joining operation, it is possible to suppress the first battery body 11 and the second battery body 21 from interfering with the joining operation, and the joining operation can be smoothly performed.

[0066] In the above-mentioned battery pack 1, the first positive electrode sheet 12 and the first conductive member 70 are joined by laser welding. According to this structure, the first positive electrode sheet 12 and the first conductive member 70 can be firmly joined. In addition, since the first positive electrode sheet 12 and the second negative electrode sheet 23 are also joined by laser welding, the joining operation can be performed under the same welding conditions, so the joining operation can be simplified.

[0067] In the above-described battery pack 1, the first conductive member 70 and the second conductive member 80 are joined by ultrasonic welding. According to this structure, the thickness of the joined portion can be made thin.

[0068] In the above-mentioned method for joining the battery pack 1, in the first step, the laser light L is irradiated in the first direction (direction from the lower side to the upper side) to join the first positive electrode sheet 12 and the second negative electrode sheet 23 by laser welding. In addition, in the second step, the laser light L is irradiated in the same first direction as in the first step to join the first positive electrode sheet 12 and the first conductive member 70 by laser welding. According to this structure, since the laser light L is irradiated from the same direction in the first step and the second step, the second negative electrode sheet 23 and the first conductive member 70 can be joined to the first positive electrode sheet 12 at the same time. Therefore, the joining operation can be simplified.

[0069] In the above-mentioned method for joining the battery pack 1, the laser light L is irradiated to a plurality of locations at a predetermined interval in the first step and the second step. According to this structure, the first positive electrode sheet 12 and the second negative electrode sheet 23 can be firmly joined. In addition, the first positive electrode sheet 12 and the first conductive member 70 can be firmly joined. In addition, when the laser light L is irradiated to a plurality of locations, the joining operation may be more complicated. However, by irradiating the laser light L from the same direction in the first step and the second step, the joining operation can be simplified even when the laser light L is irradiated to a plurality of locations. A strong joining can be performed by a simple joining operation.

[0070] An embodiment has been described above, but the specific form is not limited to the above embodiment. In the following description, the same reference numerals are attached to the same configuration as the configuration in the above description, and the description thereof is omitted.

[0071] (1) In the above-mentioned embodiment, the first positive electrode sheet 12 and the second negative electrode sheet 23 are joined by laser welding, but the structure is not limited to this. In other embodiments, the first positive electrode sheet 12 and the second negative electrode sheet 23 can also be joined by ultrasonic welding. In addition, in the above-mentioned embodiment, the first positive electrode sheet 12 and the first conductive member 70 are joined by laser welding, but the structure is not limited to this. In other embodiments, the first positive electrode sheet 12 and the first conductive member 70 can also be joined by ultrasonic welding. Using this structure, the first positive electrode sheet 12 and the second negative electrode sheet 23 can also be firmly joined. In addition, the first positive electrode sheet 12 and the first conductive member 70 can be firmly joined.

[0072] (2) In laser welding, the position, direction, and number of irradiation lasers L are not particularly limited. For example, the lasers L may be irradiated to a position of the first positive electrode sheet 12 close to the second curved portion 37 (a position of the second negative electrode sheet 23 close to the second curved portion 57). In addition, the lasers L may be irradiated in a direction from the upper side toward the lower side (a direction opposite to the above-mentioned embodiment). In addition, the lasers L may be irradiated to only one portion of the first positive electrode sheet 12 (only one portion of the second negative electrode sheet 23).

[0073] (3) In the above-mentioned embodiment, the first positive electrode sheet 12 of the first cell 10 and the second negative electrode sheet 23 of the second cell 20 are joined. That is, the first cell 10 and the second cell 20 are connected in series. However, it is not limited to this structure. In other embodiments, the first positive electrode sheet 12 of the first cell 10 and the second positive electrode sheet 22 of the second cell 20 may be joined. Alternatively, the first negative electrode sheet 13 of the first cell 10 and the second negative electrode sheet 23 of the second cell 20 may be joined. That is, the first cell 10 and the second cell 20 may be connected in parallel.

[0074] (4) In the above embodiment, the first conductive member 70 and the second negative electrode sheet 23 are adjacent to each other in the left-right direction. However, the present invention is not limited to this structure. The first conductive member 70 and the second negative electrode sheet 23 may be adjacent to each other in the front-back direction.

[0075] The specific examples of the present invention are described in detail above, but these are only examples and are not intended to limit the claims. The technology described in the claims includes structures that have been subjected to various deformations and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings exert technical usefulness in a single manner or through various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the technology illustrated in this specification or the drawings can achieve multiple purposes at the same time, and achieving one of the purposes itself has technical usefulness.

[0076] Description of Reference Numerals

[0077] 1. Battery pack; 2. Cell; 10. 1st cell; 11. 1st battery body; 12. 1st positive electrode sheet; 13. 1st negative electrode sheet; 20. 2nd cell; 21. 2nd battery body; 22. 2nd positive electrode sheet; 23. 2nd negative electrode sheet; 41. 1st electrode surface; 43. 1st part; 44. 2nd part; 62. 2nd electrode surface; 70. 1st conductive component; 71. 1st conductive surface; 73. 1st part; 74. 2nd part; 80. 2nd conductive component.

Claims

1. A battery pack, wherein: The battery pack has: a first battery cell; and a second cell overlapping the first cell, The first cell includes a first cell body and a first electrode sheet protruding from the first cell body. The second cell includes a second cell body and a second electrode sheet protruding from the second cell body and joined to the first electrode sheet. The first electrode sheet has a first electrode surface facing the second electrode sheet. The first electrode surface includes a portion to which the second electrode sheet is bonded and a portion to which the second electrode sheet is not bonded. A first conductive member is bonded to a portion of the first electrode surface to which the second electrode sheet is not bonded, and is bonded to the side of the second electrode sheet in a direction perpendicular to a direction in which the first electrode sheet protrudes and a direction perpendicular to a direction in which the first electrode sheet and the second electrode sheet overlap. In the direction in which the first cell and the second cell overlap, the first electrode sheet, the second electrode sheet, and the first conductive member do not extend beyond a space between the first cell and the second cell. The first conductive member has a first conductive surface facing the first electrode sheet. The first conductive surface includes a portion bonded to the first electrode sheet and a portion not bonded to the first electrode sheet. A second conductive member is joined to a portion of the first conductive surface that is not joined to the first electrode sheet.

2. The battery pack according to claim 1, wherein: The second electrode sheet is joined to a tip portion of the first electrode sheet in a direction in which the first electrode sheet protrudes.

3. The battery pack according to claim 1 or 2, wherein: The first conductive member extends in a direction in which the first electrode sheet protrudes, one end of the first conductive member is joined to the first electrode sheet, and the other end of the first conductive member protrudes from the first electrode sheet.

4. The battery pack according to claim 1 or 2, wherein: The first electrode sheet and the second electrode sheet are joined by laser welding.

5. The battery pack according to claim 4, wherein: The first electrode sheet and the second electrode sheet are laser welded at a position closer to the tip side than the center portion of the surface of the first electrode.

6. The battery pack according to claim 1 or 2, wherein: The first electrode sheet and the second electrode sheet are bonded together by ultrasonic welding.

7. The battery pack according to claim 1 or 2, wherein: The first electrode sheet and the first conductive member are joined by laser welding.

8. The battery pack according to claim 1, wherein: The first conductive member and the second conductive member are joined by ultrasonic welding.

9. A method for joining a battery pack including a first cell and a second cell overlapping the first cell, wherein: The first cell includes a first cell body and a first electrode sheet protruding from the first cell body. The second cell includes a second cell body and a second electrode sheet protruding from the second cell body. The first electrode sheet has a first electrode surface facing the second electrode sheet. The joining method includes: A first step is to bond the second electrode sheet to a part of the surface of the first electrode; and In a second step, a first conductive member is bonded to a portion of the first electrode surface to which the second electrode sheet is not bonded, in a direction perpendicular to a direction in which the first electrode sheet protrudes and a direction perpendicular to a direction in which the first electrode sheet and the second electrode sheet overlap, next to the second electrode sheet. In the direction in which the first cell and the second cell overlap, the first electrode sheet, the second electrode sheet, and the first conductive member do not extend beyond a space between the first cell and the second cell. The first conductive member has a first conductive surface facing the first electrode sheet. The first conductive surface includes a portion bonded to the first electrode sheet and a portion not bonded to the first electrode sheet. The joining method further comprises: In a third step, a second conductive member is joined to a portion of the first conductive surface that is not in contact with the first electrode sheet.

10. The bonding method according to claim 9, wherein: In the first step, the first electrode sheet and the second electrode sheet are joined by laser welding by irradiating the electrode sheet in a first direction. In the second step, the first electrode sheet and the first conductive member are bonded to each other by laser welding by irradiating the laser in the first direction similar to that in the first step.

11. The bonding method according to claim 10, wherein: In the first step and / or the second step, a plurality of locations are irradiated with laser light.

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