JP6650326B2 - Battery pack and method of manufacturing battery pack - Google Patents

Description

  The present invention relates to an assembled battery in which a plurality of unit cells are stacked and a method for manufacturing the assembled battery.

  2. Description of the Related Art Conventionally, there is an assembled battery in which a plurality of unit cells each having a flat battery body are stacked (see Patent Document 1). The unit cell includes an electrode tab connected to a current collector foil constituting an electrode in the power generation element and transmitting and receiving a current. The electrode tabs of each cell are electrically connected by a bus bar having conductivity.

  In Patent Literature 1, the bus bar includes a concave portion and a convex portion which are formed in a wave shape in a direction orthogonal to the laminating direction so that each electrode tab is sandwiched independently in the laminating direction. The electrode tab of each unit cell is joined to the bus bar in a state of being independently inserted into a plurality of recesses of the bus bar (for example, see Patent Document 1).

JP-T-2012-515418A

  In order to improve the connection quality between the electrode tab and the bus bar in the configuration of Patent Literature 1, it is necessary to join the electrode tab in a state where the tip of the electrode tab is sufficiently inserted into the recess of the bus bar. However, there is variation in each position of the unit cells in a direction intersecting the stacking direction of the unit cells. Therefore, when the tip of the electrode tab is to be inserted into the recess of the bus bar in the configuration of Patent Document 1, the tip of the electrode tab of the unit cell that is shifted toward the side near the bus bar is sufficiently inserted into the recess of the bus bar. However, the tip of the electrode tab of the unit cell shifted farther from the bus bar is not always fully inserted into the recess of the bus bar.

  In order to fully insert the tip of the electrode tab of a unit cell that is farther away from the bus bar into the recess of the bus bar, it is necessary to bring the bus bar closer to the unit cell. However, from the state where the tip of the electrode tab of the unit cell shifted to the side closer to the bus bar is sufficiently inserted into the recess of the bus bar, when the bus bar is further moved closer to the unit cell, the unit cell shifted to the closer side. Of the electrode tab is pushed by the bus bar. Therefore, there is a problem that a load is applied to the electrode tab. As a result, for example, the electrical connection between the current collector foil and the electrode tabs constituting the electrode in the power generation element may be unstable.

  An object of the present invention is to improve the connection quality between an electrode tab and a bus bar while reducing the load on the electrode tab even when the positions of the cells in the direction intersecting the cell stacking direction vary. An object of the present invention is to provide an assembled battery and a method of manufacturing the assembled battery.

  To achieve the above object, an assembled battery according to the present invention includes a battery group in which a plurality of flat cells having electrode tabs for transmitting and receiving current are stacked in a thickness direction thereof, and at least two flat battery cells are attached to the battery group. And a plate-shaped bus bar for electrically connecting the electrode tabs of the single cells. The bus bar has a main part extending along the stacking direction of the unit cells, and a plurality of convex parts protruding from the main part toward each of the electrode tabs. Each of the electrode tabs corresponds to a base end extending toward the main part of the bus bar and a base end that is continuous with the base end through the bending point and extends in a direction intersecting the direction in which the base end extends. And a tip portion abutting on the convex portion.

  Further, a method of manufacturing an assembled battery according to the present invention for achieving the above object is a flat unit cell including an electrode tab for transmitting and receiving a current, wherein the electrode tab has a base end extending in one direction. And a distal end portion that is continuous with the base end portion via the inflection point and extends in a direction crossing the one direction. Further, a plate-shaped bus bar electrically connecting the electrode tabs of at least two unit cells, wherein a plurality of convex portions projecting from the plate-shaped main part are prepared, and the unit cell is prepared. A plurality of batteries are stacked in the thickness direction to form a battery group. Then, by attaching the bus bar to the battery group in a state where the main portion is along the stacking direction of the unit cells and each of the plurality of convex portions is directed to the corresponding electrode tab, the tip portion of each electrode tab and the bus bar are attached. Are brought into contact with the corresponding projections.

  ADVANTAGE OF THE INVENTION According to the assembled battery and the manufacturing method of an assembled battery which concern on this invention, an electrode tab bends at a bending point when the front-end | tip part of an electrode tab is pushed by the bus bar. Due to the bending operation, at least a part of the force applied from the bus bar to the tip of the electrode tab due to the tip of the electrode tab being pushed by the bus bar is absorbed. Therefore, while reducing the load on the electrode tab shifted to the side closer to the bus bar, the tip of the electrode tab of the unit cell shifted to the side farther from the bus bar can be sufficiently brought into contact with the bus bar. Therefore, even when the positions of the cells in the direction intersecting the cell stacking direction vary, the connection quality between the electrode tabs and the bus bars can be improved while reducing the load on the electrode tabs. And a method for manufacturing the assembled battery.

It is a perspective view which shows the battery pack which concerns on embodiment. FIG. 2 is an exploded perspective view showing a protective cover, a bus bar unit, and a battery group by removing an upper pressure plate, a lower pressure plate, and left and right side plates from the battery pack shown in FIG. 1. FIG. 4 is a perspective view schematically showing a state in which an anode-side electrode tab of a first cell sub-assembly and a cathode-side electrode tab of a second cell sub-assembly are joined by a bus bar. It is a perspective view which shows the principal part in the state which joined the bus bar to the electrode tab of the laminated unit cell by a cross section. FIG. 4B is a side view showing FIG. 4A from the side. FIG. 4B is an enlarged view of a region 5A shown in FIG. 4B with the bus bar removed. FIG. 4B is an enlarged view of a region 5A shown in FIG. 4B. It is an enlarged view of area | region 6A shown in FIG. 5A. FIG. 6B is an enlarged view corresponding to FIG. 6A and illustrating a state in which a bending portion is bent. 5 is a flowchart illustrating a method of manufacturing the battery pack according to the embodiment. It is a perspective view which shows typically the state which attached some members of the bus bar unit to the battery group. It is a perspective view showing typically the state where the bus bar of the bus bar unit is laser-welded to the electrode tab of the unit cell. FIG. 4B is a cross-sectional view corresponding to FIG. 4B in a state where the bus bar is laser-joined to the electrode tabs of the stacked unit cells. It is an enlarged view of the area | region 11 shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. The size and ratio of each member in the drawings are exaggerated for convenience of explanation and may be different from the actual size and ratio. In the drawing, the azimuth is indicated using arrows represented by X, Y, and Z. The direction of the arrow represented by X crosses the stacking direction of the single cells 110 and indicates a direction along the longitudinal direction of the single cells 110. The direction of the arrow represented by Y indicates the direction that intersects the stacking direction of the cells 110 and extends along the short direction of the cells 110. The direction of the arrow represented by Z indicates the stacking direction of the unit cells 110.

  First, the battery pack 100 of the present embodiment will be described with reference to FIGS.

  FIG. 1 is a perspective view showing an assembled battery 100 according to the present embodiment. FIG. 2 is an exploded view of the assembled battery 100 shown in FIG. 1 in which the upper pressing plate 151, the lower pressing plate 152, and the left and right side plates 153 are removed, and the protective cover 140, the bus bar unit 130, and the battery group 100G are disassembled. It is a perspective view. FIG. 3 shows a busbar in which the anode-side electrode tab 113A of the first cell sub-assembly 100M (unit cells 110 connected in parallel for every three pairs) and the cathode-side electrode tab 113K of the second cell subassembly 100N (unit cells 110 connected in parallel for every three units). It is a perspective view which shows the state joined by 131 typically disassembled. FIG. 4A is a perspective view showing a cross section of a main part in a state where the bus bar 131 is joined to the electrode tab 113 of the stacked unit cells 110. FIG. 4B is a side view showing FIG. 4A from the side. FIG. 5A is an enlarged view of area 5A shown in FIG. 4B with bus bar 131 removed. FIG. 5B is an enlarged view of a region 5A shown in FIG. 4B. FIG. 6A is an enlarged view of a region 6A shown in FIG. 5A. FIG. 6B is an enlarged view corresponding to FIG. 6A showing a state in which the bending portion 113d is bent.

  In the state shown in FIG. 1, the left front side is referred to as the “front side” of the entire battery pack 100 and each component, the right rear side is referred to as the “back side” of the entire battery pack 100 and each component, and the right hand side. The front side and the back side of the left hand are referred to as the left and right “sides” of the entire battery pack 100 and each component. 2, 8 and 9, the projection 131b of the bus bar 131 is omitted.

  As shown in FIGS. 1 and 2, the battery pack 100 has a stacked body 100S including a battery group 100G in which a plurality of flat cells 110 are stacked in the thickness direction. The assembled battery 100 further includes a protective cover 140 attached to the front side of the stacked body 100S, and a housing 150 that accommodates the stacked body 100S in a state where each of the unit cells 110 is pressed along the stacking direction Z of the unit cells 110. And The stacked body 100S includes a battery group 100G, and a bus bar unit 130 attached to the front side of the battery group 100G and integrally holding a plurality of bus bars 131. The protection cover 140 covers and protects the bus bar unit 130. The bus bar unit 130 includes a plurality of bus bars 131 and a bus bar holder 132 for integrally attaching the plurality of bus bars 131 in a matrix. Of the plurality of bus bars 131, an anode-side terminal 133 is attached to an end on the anode side, and a cathode-side terminal 134 is attached to an end on the cathode side.

  The assembled battery 100 of the present embodiment is, in brief, attached to the battery group 100G and a battery group 100G in which a plurality of flat unit cells 110 each having an electrode tab 113 for transmitting and receiving a current are stacked in the thickness direction. And a plate-shaped bus bar 131 for electrically connecting the electrode tabs 113 of at least two unit cells 110 to each other. The bus bar 131 has a main portion 131a extending along the stacking direction Z of the unit cells 110, and a plurality of convex portions 131b projecting from the main portion 131a toward each of the electrode tabs 113. Each of the electrode tabs 113 is continuous with the base end 113a extending toward the main part 131a of the bus bar 131 and the base end 113a through the bending point 113b, and extends in the direction X1 in which the base end 113a extends. A leading end 113c extending in the intersecting direction and abutting on the corresponding convex portion 131b. Hereinafter, the battery pack 100 of the present embodiment will be described in detail.

  As shown in FIG. 3, the battery group 100G includes a first cell sub-assembly 100M including three unit cells 110 electrically connected in parallel and a second cell sub-assembly 100N including three other unit cells 110 electrically connected in parallel. And are connected in series by a bus bar 131.

  As described later with reference to FIGS. 5A and 5B, the electrode tab 113 has a bent shape at a bending point 113b. The first cell subassembly 100M and the second cell subassembly 100N have the same configuration except for the bending direction of the tip 113c of the electrode tab 113 of the unit cell 110. Specifically, the second cell subassembly 100N is obtained by reversing the top and bottom of the unit cell 110 included in the first cell subassembly 100M. In the present embodiment, the lower side in the stacking direction Z such that the bending direction of the distal end 113c of the electrode tab 113 of the second cell subassembly 100N is the same as the bending direction of the distal end 113c of the electrode tab 113 of the first cell subassembly 100M. Are aligned. Each unit cell 110 has a pair of spacers 120 (first spacer 121 and second spacer 122) attached thereto.

  The unit cell 110 corresponds to, for example, a flat lithium ion secondary battery. As shown in FIGS. 4A and 4B, the cell 110 has a battery body 110H in which a power generation element 111 is sealed with a pair of laminated films 112, and is electrically connected to the power generation element 111 and led out from the battery body 110H. And a thin plate-shaped electrode tab 113. The external dimensions of the cell 110 can be, for example, a length in the longitudinal direction X of 280 mm to 300 mm, a length in the short direction Y of 200 to 225 mm, and a thickness of 5 to 10 mm, but are not limited thereto.

  The power generating element 111 is configured by laminating a plurality of members each having a positive electrode and a negative electrode sandwiched between separators. The power generating element 111 supplies power while receiving and supplying power from the outside, and discharging to an external electric device.

  The laminate film 112 is configured by covering both sides of the metal foil with an insulating sheet. The pair of laminate films 112 cover the power generating element 111 from both sides along the laminating direction Z, and seal four sides thereof. As shown in FIGS. 4A and 4B, the pair of laminate films 112 are formed by leading the anode-side electrode tab 113A and the cathode-side electrode tab 113K outward from between the one end portions 112a along the short direction Y. I have.

  The electrode tab 113 includes an anode-side electrode tab 113A and a cathode-side electrode tab 113K, as shown in FIGS. 3, 4A and 4B, and is separated from one end 112a of the pair of laminated films 112 from each other. Extends outward. The anode-side electrode tab 113A is made of aluminum in accordance with the characteristics of the anode-side components in the power generation element 111. The cathode-side electrode tab 113K is made of copper in accordance with the characteristics of the cathode-side components in the power generation element 111. The thickness of the anode-side electrode tab 113A may be, for example, 0.4 mm. The thickness of the cathode-side electrode tab 113K may be, for example, 0.2 mm.

  As shown in FIG. 3, the assembled battery 100 includes three cells 110 electrically connected in parallel (first cell subassembly 100M) and another three cells 110 electrically connected in parallel (second cell subassembly 100N). Are connected in series. Therefore, the top and bottom of the unit cell 110 are exchanged for each of the three unit cells 110 so that the positions of the anode-side electrode tab 113A and the cathode-side electrode tab 113K of the unit cell 110 intersect in the stacking direction Z. I have.

  In the first cell subassembly 100M shown in the lower part of FIG. 3, the anode-side electrode tab 113A is arranged on the right side in the figure, and the cathode-side electrode tab 113K is arranged on the left side in the figure. On the other hand, in the second cell subassembly 100N shown in the upper part of FIG. 3, the cathode side electrode tab 113K is arranged on the right side in the figure, and the anode side electrode tab 113A is arranged on the left side in the figure.

  In addition, as shown in FIG. 3, the distal end portion 113c of each electrode tab 113 is disposed on the same surface side of the multilayer body 100S. A double-sided tape 160 is attached to the unit cells 110 located on the upper surfaces of the first cell sub-assembly 100M and the second cell sub-assembly 100N.

  As will be described later with reference to FIGS. 5A and 5B, the electrode tab 113 has a bent shape at a bending point 113b, and the electrode tab 113 is simply replaced with the top and bottom of each of the three cells 110. Are not aligned. For this reason, in the present embodiment, the electrode tabs 113 are bent so that the distal ends 113c of the electrode tabs 113 of all the cells 110 are lower than the base end 113a of the electrode tabs 113 along the stacking direction Z. .

  As shown in FIG. 3, the pair of spacers 120 (the first spacer 121 and the second spacer 122) are provided between the stacked unit cells 110.

  As shown in FIGS. 3 and 4B, the first spacer 121 is disposed along one end 112a of the laminate film 112 from which the electrode tab 113 of the unit cell 110 protrudes. As shown in FIGS. 1 and 2, the first spacer 121 has a stacked reference surface 121a with which the bus bar unit 130 contacts.

  The second spacer 122 is provided along the other end 112b of the laminate film 112, as shown in FIG.

  Each of the unit cells 110 is laminated with a pair of spacers 120 (first spacer 121 and second spacer 122) and then laminated in the laminating direction Z. The pair of spacers 120 (the first spacer 121 and the second spacer 122) are made of reinforced plastics having an insulating property.

  The busbar unit 130 includes a plurality of busbars 131 integrally as shown in FIG. The bus bar 131 is made of a metal having conductivity, and electrically connects the tip portions 113c of the electrode tabs 113 of at least two unit cells 110.

  As shown in FIG. 3, the bus bar 131 includes an anode-side bus bar 131A that is laser-welded to the anode-side electrode tab 113A of one cell 110, and a cathode-side electrode tab of another cell 110 that is adjacent along the stacking direction Z. The cathode side bus bar 131K to be laser welded to the 113K is joined and integrally formed.

  The anode-side bus bar 131A and the cathode-side bus bar 131K have the same shape, and are each formed in an L shape. The anode-side bus bar 131A and the cathode-side bus bar 131K are overlapped with the top and bottom inverted. Specifically, the bus bar 131 joins a bent portion of one end of the anode-side bus bar 131A along the stacking direction Z and a bent portion of one end of the cathode-side bus bar 131K along the stacking direction Z, It is integrated.

  The anode-side bus bar 131A is made of aluminum similarly to the anode-side electrode tab 113A. The cathode-side bus bar 131K is made of copper, similarly to the cathode-side electrode tab 113K. The anode-side bus bar 131A and the cathode-side bus bar 131K made of different metals are joined to each other by ultrasonic joining. The thickness of the anode-side bus bar 131A may be, for example, 0.6 mm. The thickness of the cathode-side bus bar 131K may be, for example, 0.4 mm.

  As illustrated in FIG. 3, when the assembled battery 100 is configured by connecting a plurality of sets of three unit cells 110 connected in parallel over a plurality of sets, as illustrated in FIG. Laser welding is performed on the anode-side electrode tabs 113A of the three unit cells 110 adjacent to each other along the stacking direction Z. Similarly, the bus bar 131 laser-welds the portion of the cathode-side bus bar 131K to the cathode-side electrode tabs 113K of three cells 110 adjacent to each other along the stacking direction Z.

  However, among the bus bars 131 arranged in a matrix, the bus bar 131 (indicated by reference numeral 131 (A) in FIG. 8) located at the upper right in the drawing of FIG. 8 has 21 unit cells 110 (3 parallel, 7 series). , And is composed of only the anode-side bus bar 131A. The anode-side bus bar 131A is laser-bonded to the anode-side electrode tabs 113A of the three uppermost unit cells 110 of the battery group 100G. Similarly, among the bus bars 131 arranged in a matrix, the bus bar 131 (indicated by reference numeral 131 (B) in FIG. 8) located at the lower left in FIG. ) Corresponds to the cathode-side terminal, and is composed of only the cathode-side bus bar 131K. The cathode-side bus bar 131K is laser-bonded to the cathode-side electrode tabs 113K of the three lowermost cells 110 of the battery group 100G.

  As shown in FIG. 2, the bus bar holder 132 integrally holds a plurality of bus bars 131 in a matrix so as to face the electrode tabs 113 of each of the unit cells 110 that are stacked. The bus bar holder 132 is made of a resin having an insulating property and is formed in a frame shape.

  As shown in FIG. 2, the anode-side terminal 133 corresponds to the anode-side terminal of the battery group 100G formed by alternately stacking the first cell sub-assemblies 100M and the second cell sub-assemblies 100N. The anode-side terminal 133 is made of a conductive metal plate.

  As shown in FIG. 2, the cathode terminal 134 corresponds to a cathode-side terminal of the battery group 100G formed by alternately stacking the first cell subassemblies 100M and the second cell subassemblies 100N. The cathode terminal 134 is made of a conductive metal plate.

  In the present embodiment, the electrode tab 113 and the bus bar 131 are connected by the contact between the electrode tab 113 and the bus bar 131. With reference to FIGS. 5A, 5B, 6A, and 6B, a configuration related to contact between the electrode tab 113 and the bus bar 131 will be described in further detail.

  Referring to FIGS. 5A, 5B, 6A and 6B, battery pack 100 reduces at least a part of force F acting on electrode tab 113 due to being pushed by bus bar 131, by bending electrode tab 113. It has an absorbing structure that absorbs by operation. Specifically, the bus bar 131 includes a main portion 131a extending along the stacking direction Z of the unit cells 110, and a plurality of convex portions 131b protruding from the main portion 131a toward each of the electrode tabs 113. Have. Each of the electrode tabs 113 is continuous with the base end 113a extending toward the main part 131a of the bus bar 131 and the base end 113a via the bending point 113b, in the direction in which the base end 113a extends. A tip portion 113c extending in a direction intersecting X1 and abutting on a corresponding convex portion 131b.

  As shown in FIG. 4B, there are variations in the positions of the cells 110 in the direction X that intersects the stacking direction Z. Therefore, when the bus bar 131 is attached to the battery group 100G such that the electrode tab 113 of the cell 110 that is shifted farther away from the bus bar 131 and the bus bar 131 abut, the cell 110 that is shifted closer to the bus bar 131 is shifted. The tip portion 113 c of the electrode tab 113 is pushed by the bus bar 131. When the tip 113c of the electrode tab 113 is pressed by the bus bar 131, for example, a problem occurs in that the electrical connection between the current collector foil constituting the electrode and the electrode tab 113 in the power generation element 111 becomes unstable. There is a risk.

  As described above, each of the electrode tabs 113 is continuous with the base end 113a extending toward the main part 131a of the bus bar 131 and the base end 113a through the bending point 113b, and the base end 113a extends. And a tip portion 113c extending in a direction intersecting the direction X1 and abutting on the corresponding convex portion 131b.

  As a result, the electrode tab 113 of the unit cell 110 (A) that is displaced closer to the bus bar 131 is changed from the state shown in FIG. 5A to the state shown in FIG. 5B due to the tip 113c being pushed by the bus bar 131. To bend at the bending point 113b. By this bending operation, the electrode tab 113 can absorb at least a part of the force F acting on the distal end portion 113c when pushed from the bus bar 131. Therefore, even if the positions of the cells 110 in the direction X intersecting with the stacking direction Z vary, the load on the electrode tab 113 is reduced, and the electrodes of the cells 110 shifted far from the bus bar 131 are reduced. The tab 113 and the bus bar 131 can be sufficiently contacted. As a result, the electric connection between the electrode tab 113 and the bus bar 131 can be prevented without causing a problem such as an unstable electrical connection between the current collector foil constituting the electrode and the electrode tab 113 in the power generation element 111. Connection quality can be improved. Furthermore, laser welding can be performed in a state where the tip 113c of the electrode tab 113 of the unit cell 110 and the projection 131b of the bus bar 131 are sufficiently in contact with each other, so that welding quality can be improved.

  Referring to FIG. 6A, a bending portion 113d that bends when a distal end portion 113c and a convex portion 131b are relatively pressed against each other is arranged at a base end portion 113a of the electrode tab 113 in the present embodiment. The bending portion 113d in the present embodiment has a shape in which a part of the base end portion 113a protrudes in the stacking direction Z. The size of the bending portion 113d is not limited as long as the tip portion 113c and the protrusion 131b are bent by being relatively pressed. For example, the length R2 of the bending portion 113d in the direction X1 in which the base end portion 113a extends may be 2 to 3 mm. Further, the height H2 of the bending portion 113d can be set to 2 to 3 mm.

  As shown in FIG. 6B, when the tip 113c of the electrode tab 113 is pressed by the bus bar 131, the bending portion 113d is deformed as follows. In other words, the length R2 of the bent portion 113d in the direction X1 in which the base end portion 113a extends is reduced, and the height H2 of the bent portion 113d is increased. As described above, when the bending portion 113d bends, a part of the force F acting on the tip portion 113c due to the pushing of the tip portion 113c of the electrode tab 113 by the bus bar 131 is absorbed. Therefore, the electrode tab 113 and the bus bar 131 can be sufficiently contacted while the load on the electrode tab 113 is further reduced.

  Referring to FIG. 5B again, in the present embodiment, the convex portion 131b of the bus bar 131 and the first spacer 121 are separated by a gap.

  Thus, the protrusion 131b of the bus bar 131 and the first spacer 121 are not pressed relatively to each other, and the protrusion 131b of the bus bar 131 and the tip 113c of the electrode tab 113 are in contact with each other. That is, there is no need to relatively press the convex portion 131b of the bus bar 131 and the first spacer 121 in order to make the convex portion 131b of the bus bar 131 abut on the distal end portion 113c of the electrode tab 113. Therefore, when manufacturing the assembled battery 100, a jig for pressing the convex portion 131b of the bus bar 131 and the first spacer 121 relatively is not required, so that the manufacture of the assembled battery 100 is facilitated. In addition, since it is not necessary to provide the first spacer 121 with a portion on which the protrusion 131b of the bus bar 131 is pressed, the first spacer 121 can be reduced in size and the battery pack 100 can be reduced in weight.

  Further, since a gap is formed between the convex portion 131b of the bus bar 131 and the first spacer 121, heat applied when the distal end portion 113c of the electrode tab 113 and the bus bar 131 are laser-welded, Propagation to one spacer 121 can be prevented. Therefore, it is possible to prevent the first spacer 121 from being damaged when the electrode tab 113 and the bus bar 131 are laser-welded.

  The dimensions of the base 113a and the tip 113c of the electrode tab 113, the dimensions of the protrusion 131b of the bus bar 131, and the initial value α1 of the angle α formed between the base 113a and the tip 113c are as long as the following conditions are satisfied. Not limited. That is, there is no limitation as long as the condition that at least a part of the force F acting on the electrode tab 113 due to being pushed by the bus bar 131 is absorbed by the bending operation of the electrode tab 113 is satisfied. However, referring to FIG. 5A, initial value α1 of angle α is a value of angle α formed between base end 113a of electrode tab 113 and tip 113c in a state where tip 113c is not in contact with bus bar 131. is there. In the present embodiment, the electrode tabs 113 are configured so that the electrode tabs 113 of all the cells 110 have the same initial value α1, but the present invention is not limited to this.

  In the present embodiment, the dimensions and the like described above are determined so as to satisfy the following conditions (i) and (ii) in addition to the above conditions. That is, (i) when the bus bar 131 is attached to the battery group 100G, the contact between the tip portions 113c of the electrode tabs 113 of all the cells 110 and the projection 131b of the bus bar 131 is completed, and (ii) the bus bar 131 Is attached to the battery group 100G, the angle α2 formed between the base end 113a and the front end 113c of the electrode tab 113 of the unit cell 110 (A) shifted to the position closest to the bus bar 131 is 90 ° or more. It is determined to satisfy the condition of being maintained.

  Referring to FIG. 5A, as a dimension satisfying the above-described conditions (i) and (ii), length P of base end portion 113a of electrode tab 113 may be, for example, 6 to 8 mm. Further, the length Q of the distal end portion 113c of the electrode tab 113 can be 5 to 6 mm. However, the length P of the base end portion 113a of the electrode tab 113 in the present embodiment means the distance from the junction between the electrode tab 113 and the battery body 110H in the direction X intersecting the stacking direction Z to the bending point 113b. I do.

  Referring to FIG. 5B, length R1 of protrusion 131b in stacking direction Z may be, for example, 2 to 3 mm. Further, the height H1 of the protrusion 131b may be, for example, 2 to 3 mm.

  Then, the initial value α1 of the angle α formed between the base end 113a and the front end 113c can be determined, for example, as follows.

  Referring to FIG. 2, bus bar unit 130 is attached to battery group 100 </ b> G in a state where bus bar unit 130 is in contact with lamination reference surface 121 a of first spacer 121. At this time, as shown in FIG. 4B, the bus bar 131 is arranged at a position away from the lamination reference plane 121a by a predetermined distance U. On the other hand, as described above, the positions of the stacked unit cells 110 in the direction X intersecting with the stacking direction Z vary. Therefore, when the bus bar 131 is arranged at a position separated by a predetermined distance U from the lamination reference surface 121a, the distance D (see FIG. 5B) between the bus bar 131 and the battery body 110H varies. Here, the distance between the battery body 110H of the unit cell 110 (A) closest to the bus bar 131 and the bus bar 131 is Dmin, and the unit cell 110 (B) shifted to the position farthest from the bus bar 131. The distance between the battery main body 110H and the bus bar 131 is defined as Dmax.

  The distance Dmin and the distance Dmax can be calculated by a known method based on a molding error of the first spacer 121, a molding error of the battery body 110H, and the like. The initial value α1 of the angle α is based on the distances Dmax and Dmin, the length P of the base end 113a and the length Q of the front end 113c, and the length R1 and height H1 of the projection 131b. , Conditions (i) and (ii) can be determined by known geometric methods.

  As shown in FIGS. 1 to 3, the protective cover 140 covers the bus bar unit 130, so that the bus bars 131 are short-circuited, or the bus bar 131 contacts an external member to cause a short-circuit or a short circuit. To prevent Furthermore, the protection cover 140 causes the anode-side terminal 133 and the cathode-side terminal 134 to face the outside, and causes the power generation elements 111 of each unit cell 110 to charge and discharge. The protective cover 140 is made of plastics having an insulating property.

  As shown in FIG. 3, the protective cover 140 is formed in a flat plate shape and stands up along the stacking direction Z. The protective cover 140 has a shape in which the upper end 140b and the lower end 140c of the side surface 140a are bent along the longitudinal direction X, and is fitted to the bus bar unit 130.

  As shown in FIGS. 2 and 3, the side surface 140 a of the protective cover 140 has a rectangular hole slightly larger than the anode terminal 133 at a position corresponding to the anode terminal 133 provided in the bus bar unit 130. A first opening 140d is provided. Similarly, the side surface 140 a of the protective cover 140 has a second opening 140 e formed of a rectangular hole slightly larger than the cathode terminal 134 at a position corresponding to the cathode terminal 134 provided in the bus bar unit 130. I have.

  The housing 150 houses the battery group 100G in a state where the battery group 100G is pressed in the stacking direction Z, as shown in FIGS. The housing 150 has an upper pressing plate 151 and a lower pressing plate 152 that press the battery group 100G while sandwiching it from above and below in the stacking direction Z. Further, the housing 150 has a pair of side plates 153 that fix the relative positions of the upper pressing plate 151 and the lower pressing plate 152 so that the upper pressing plate 151 and the lower pressing plate 152 do not separate from each other. The upper pressure plate 151 and the lower pressure plate 152 apply an appropriate surface pressure to the power generation element 111. The upper pressure plate 151 and the side plate 153 are joined by laser welding. Similarly, the lower pressing plate 152 and the side plate 153 are joined by laser welding.

  Next, a method of manufacturing the battery pack 100 will be described with reference to FIGS.

  FIG. 7 is a flowchart illustrating a method of manufacturing the battery pack 100 according to the present embodiment. FIG. 8 is a perspective view schematically showing a state where some members of the bus bar unit 130 are attached to the battery group 100G. FIG. 9 is a perspective view schematically showing a state in which the bus bar 131 of the bus bar unit 130 is laser-welded to the electrode tab 113 of the unit cell 110. FIG. 10 is a cross-sectional view corresponding to FIG. 4B in a state where the bus bar 131 is laser-bonded to the electrode tab 113 of the stacked unit cells 110. FIG. 11 is an enlarged view of the area 11 shown in FIG.

  The manufacturing method (manufacturing process) of the assembled battery 100 includes a process of preparing the cell 110 (step S1), a process of preparing the bus bar 131 (step S2), and forming the battery group 100G by stacking the cells 110. The method includes a step (step S3), a step of attaching the bus bar 131 to the battery group 100G (step S4), and a step of joining the electrode tab 113 and the bus bar 131 (step S5). Hereinafter, each step will be described in detail.

  In the step of preparing a unit cell (step S1), a flat unit cell 110 having an electrode tab 113 for transmitting and receiving a current is prepared. In the present embodiment, the electrode tab 113 has a proximal end 113a extending in one direction X1 and a distal end continuing to the proximal end 113a via a bending point 113b and extending in a direction intersecting the one direction X1. A cell 110 having a portion 113c is prepared (see FIG. 5A).

  In the step of preparing the bus bar 131 (step S2), a plate-shaped bus bar 131 for electrically connecting the electrode tabs 113 of at least two unit cells 110 is prepared. In the present embodiment, a bus bar 131 having a plurality of convex portions 131b protruding from a plate-shaped main portion 131a is prepared (see FIG. 5B).

  In the step of stacking the cells 110 to form the battery group 100G (step S3), a plurality of the cells 110 to which the pair of spacers 120 (the first spacer 121 and the second spacer 122) are attached are stacked in the thickness direction. Thus, a battery group 100G is formed (see FIGS. 2 and 3). The battery group 100G is housed in the housing 150 in a state where the battery group 100G is pressed along the stacking direction Z of the battery group 100G. The stacking of the cells 110 and the housing of the battery group 100G in the housing 150 are performed on the mounting table 701 (see FIG. 8).

  In the step of attaching the bus bar 131 to the battery group 100G (step S4), as shown in FIGS. 5B and 8, the main portion 131a is arranged along the stacking direction Z of the unit cells 110, and each of the plurality of convex portions 131b is connected. The bus bar 131 is attached to the battery group 100G while facing the corresponding electrode tab 113. Then, by attaching the bus bars 131 to the battery group 100G, the tip portions 113c of the respective electrode tabs 113 and the corresponding protrusions 131b of the bus bars 131 are brought into contact. In the present embodiment, the bus bar 131 is attached by bringing the bus bar unit 130 into contact with the lamination reference surface 121a of the first spacer 121. The attachment of the bus bar 131 to the battery group 100G can be performed using, for example, a robot arm.

  As described above, the electrode tab 113 has a proximal end 113a extending in one direction X1 and a distal end continuing to the proximal end 113a via a bending point 113b and extending in a direction intersecting in one direction X1. Part 113c.

  Thereby, when the tip 113c of the electrode tab 113 and the projection 131b of the bus bar 131 are pressed relatively, the electrode tab 113 is bent at the bending point 113b. By this bending operation, the electrode tab 113 can absorb at least a part of the force F acting on the distal end portion 113c when pushed from the bus bar 131. Therefore, even if the positions of the cells 110 in the direction X intersecting with the stacking direction Z vary, the load on the electrode tab 113 is reduced, and the electrodes of the cells 110 shifted far from the bus bar 131 are reduced. The tab 113 and the bus bar 131 can be sufficiently contacted. As a result, the connection quality between the electrode tab 113 and the bus bar 131 can be improved.

  Further, even if the positions of the cells 110 in the direction X intersecting with the stacking direction Z vary, the electrode tab 113 of the cell 110 that is shifted far from the bus bar 131 can be brought into contact with the bus bar 131. This also has the following advantages. In other words, the limitation on the variation in the position of the cells 110 in the direction X intersecting with the stacking direction Z can be relaxed, so that the positioning accuracy in the direction X intersecting with the stacking direction Z when stacking the cells 110 can be reduced. Can be coarse. Therefore, the manufacture of the battery pack 100 becomes easier.

  In the present embodiment, when the distal end portion 113c of the electrode tab 113 is brought into contact with the convex portion 131b of the bus bar 131, the angle α formed between the base end portion 113a and the distal end portion 113c of the electrode tab 113 (see FIG. 5A). From the obtuse angle state, the front end portion 113c and the convex portion 131b of the bus bar 131 are pressed relatively.

  Since the angle α formed between the base end portion 113a and the tip end portion 113c of the electrode tab 113 is an obtuse angle, the distance between the tip end side of the tip end portion 113c (the side away from the bending point 113b) and the bending point 113b is long. (See the cell 110 (B) shown in the lower part of FIG. 5B). Thereby, even if the bending point 113b of the electrode tab 113 and the bus bar 131 are separated by a longer distance, the tip 113c of the electrode tab 113 and the projection 131b of the bus bar 131 can be brought into contact. That is, the projection 131b of the bus bar 131 can be brought into contact with the tip 113c of the electrode tab 113 of the unit cell 110 (B) which is farther away from the bus bar 131. At this time, it is also possible to prevent the bending point 113b of the electrode tab 113 of the unit cell 110 (A) shifted closer to the bus bar 131 from coming into contact with the bus bar 131. As a result, even when the variation in the position of the cell 110 in the direction X intersecting the stacking direction Z is large, the electrode tab 113 and the bus bar 131 can be sufficiently contacted without applying a load to the electrode tab 113. Let me do.

  Further, in the present embodiment, when the distal end portion 113c of the electrode tab 113 and the convex portion 131b of the bus bar 131 are brought into contact with each other, the distal end portion 113c is bent while bending the bent portion 113d formed on the base end portion 113a. The protrusion 131b of the bus bar 131 is pressed relatively (see FIG. 6B).

  Thus, a part of the force F acting on the tip 113c of the electrode tab 113 from the projection 131b of the bus bar 131 can be absorbed. Therefore, the electrode tab 113 and the bus bar 131 can be brought into contact with each other while further reducing the load on the electrode tab 113.

  In the present embodiment, the following method is employed as a method of attaching the bus bars 131 to the battery group 100G so that the tip portions 113c of the respective electrode tabs 113 abut on the corresponding protrusions 131b of the bus bars 131. . That is, the dimensions of the proximal end 113a and the distal end 113c of the electrode tab 113, the dimensions of the convex portion 131b of the bus bar 131, and the initial value α1 of the angle α formed between the proximal end 113a and the distal end 113c are determined by the above-mentioned condition (i). ) Is determined.

  According to the method, if the electrode tab 113 and the bus bar 131 of the unit cell 110 are configured to have a predetermined size or the like, the bus bar 131 is attached to the battery group 100G, and the tip portion 113c of each electrode tab 113 is formed. The corresponding protrusion 131b of the bus bar 131 can be brought into contact with the bus bar 131. Therefore, when manufacturing the assembled battery 100, a jig for pressing the convex portion 131b of the bus bar 131 and the first spacer 121 relatively is not required, so that the manufacture of the assembled battery 100 is facilitated.

  In the step of joining the electrode tab 113 and the bus bar 131 (step S5), as shown in FIGS. 9 and 10, the tip 113c of the electrode tab 113 and the projection 131b of the bus bar 131 are brought into contact with each other. By irradiating the projection 131b with the laser beam L1, the electrode tab 113 and the bus bar 131 are joined.

  When there is a variation in the position of the unit cell 110 in the direction X intersecting with the stacking direction Z, the angle α formed between the base end portion 113a and the front end portion 113c when the electrode tab 113 and the bus bar 131 are in contact with each other is Variations occur (see FIG. 5B). Therefore, when the bus bar 131 does not have the protrusion 131b, the contact point 131c of the electrode tab 113 in the bus bar 131 can change along the stacking direction Z.

  On the other hand, in the present embodiment, the bus bar 131 has the protrusion 131b. Therefore, as shown in FIG. 11, the position of the contact portion 131c can change on the convex portion 131b according to the angle α formed between the base end portion 113a and the distal end portion 113c. 131b. Therefore, by irradiating the projection 131b with the laser beam L1, the tip 113c of the electrode tab 113 and the projection 131b of the bus bar 131 can be easily and reliably joined. In FIG. 11, the tip 113 c of the electrode tab 113 of the unit cell 110 (A) that is shifted to the position closest to the bus bar 131 is indicated by 113 c (A). Also, the tip 113c of the electrode tab 113 of the unit cell 110 (B) which is shifted farthest from the bus bar 131 is indicated by 113c (B).

  In the present embodiment, as shown in FIG. 9, the irradiation of the laser beam L1 is performed using a laser oscillator 705. As the laser oscillator 705, a known laser oscillator can be used. The characteristics and the like of the laser beam L1 emitted by the laser oscillator 705 are not limited as long as the electrode tab 113 and the bus bar 131 can be laser-welded.

  The output of the laser light L1 may be, for example, 1.5 to 2.5 kW. The spot diameter of the laser beam L1 can be, for example, 70 to 90 μm. By setting the spot diameter to 70 to 90 μm, the electrode tab 113 and the bus bar 131 are easily melted.

  In the present embodiment, the laser beam L1 is emitted while being swung so as to draw a wobbling shape such as an elliptical shape. By oscillating the laser beam L1, the laser beam L1 can be irradiated so as to more reliably cover the contact portion 131c between the tip portion 113c of the electrode tab 113 and the projection 131b of the bus bar 131.

  After the step of joining the electrode tab 113 and the bus bar 131 (step S5) is completed, the anode terminal 133 and the cathode terminal 134 are joined to the bus bar 131, the protective cover 140 is attached to the stacked body 100S, and the Complete manufacturing. The assembled battery 100 that has been manufactured is removed from the mounting table 701 and carried out to an inspection process for inspecting battery performance and the like.

  The manufacturing method of the assembled battery 100 described with reference to FIGS. 7 to 11 is an automatic machine that controls the entire process by a controller, a semi-automatic machine that performs a part of the process by an operator, or a manual that the operator performs the entire process. It may be embodied by any form of the machine.

  According to the battery pack 100 and the method of manufacturing the battery pack 100 according to the present embodiment described above, the following operational effects can be obtained.

  In the assembled battery 100 and the method of manufacturing the assembled battery 100 according to the present embodiment, the bus bar 131 includes the main portion 131a extending along the stacking direction Z of the unit cells 110 and the main portion 131a toward each of the electrode tabs 113. And a plurality of convex portions 131b projecting from In addition, each of the electrode tabs 113 is continuous with the base end 113a extending toward the main part 131a of the bus bar 131 and the base end 113a via the bending point 113b, in a direction in which the base end 113a extends. A tip portion 113c extending in a direction intersecting X1 and abutting on a corresponding convex portion 131b.

  According to the assembled battery 100 and the method of manufacturing the assembled battery 100 configured as described above, the electrode tab 113 bends at the bending point 113b when the distal end 113c of the electrode tab 113 is pressed by the bus bar 131. Due to the bending operation, at least a part of the force F applied from the bus bar 131 to the tip portion 113c of the electrode tab 113 due to the pushing of the tip portion 113c of the electrode tab 113 by the bus bar 131 is absorbed. Therefore, while reducing the load on the electrode tab 113 shifted to the side closer to the bus bar 131, the distal end portion 113 c of the electrode tab 113 of the unit cell 110 shifted to the side far from the bus bar 131 sufficiently contacts the bus bar 131. Let me do. Furthermore, since the tip 113c of the electrode tab 113 and the projection 131b of the bus bar 131 are in contact with each other, the tip 113c of the electrode tab 113 can be stably contacted with the bus bar 131, and the contact area increases. Therefore, even when the positions of the cells in the direction intersecting the cell stacking direction vary, the connection quality between the electrode tabs and the bus bars can be improved while reducing the load on the electrode tabs. And a method for manufacturing the assembled battery.

  In the battery pack 100 and the method of manufacturing the battery pack 100 according to the present embodiment, the distal end 113 c of the electrode tab 113 and the protrusion 131 b of the bus bar 131 are relatively pressed against the base end 113 a of the electrode tab 113. A bending portion 113d that bends due to this is disposed.

  According to the assembled battery 100 and the method of manufacturing the assembled battery 100 configured as described above, a part of the force F acting on the distal end portion 113c of the electrode tab 113 from the convex portion 131b of the bus bar 131 by bending the bending portion 113d. Can be absorbed. Thereby, the electrode tab 113 and the bus bar 131 can be brought into contact with each other while further reducing the load applied to the electrode tab 113.

  The assembled battery 100 according to the present embodiment further includes an insulating first spacer 121 that holds the electrode tab 113, and the protrusion 131b of the bus bar 131 and the first spacer 121 are separated from each other with a gap. .

  According to the assembled battery 100 configured as described above, the contact between the protrusion 131 b of the bus bar 131 and the tip 113 c of the electrode tab 113 is completed without pressing the protrusion 131 b of the bus bar 131 against the first spacer 121. Accordingly, it is not necessary to use a jig for pressing the convex portion 131b of the bus bar 131 against the first spacer 121, so that the manufacture of the battery pack 100 is facilitated. Further, it is not necessary to provide the first spacer 121 with a portion where the convex portion 131b of the bus bar 131 is pressed. Therefore, the size of the first spacer 121 can be reduced, so that the weight of the battery pack 100 can be reduced.

  In the method of manufacturing the battery pack 100 according to the present embodiment, the angle α formed between the base end 113a and the front end 113c of the electrode tab 113 between the front end 113c of the electrode tab 113 and the protrusion 131b of the bus bar 131 is an obtuse angle. Contact from state.

  According to the manufacturing method of the assembled battery 100 configured as described above, even if the bending point 113b of the electrode tab 113 and the bus bar 131 are further apart by a longer distance, the tip 113c of the electrode tab 113 and the projection 131b of the bus bar 131 can be used. Can be abutted. As a result, the protrusion 131b of the bus bar 131 can be brought into contact with the tip 113c of the electrode tab 113 of the unit cell 110 (B) which is shifted to a position farther from the bus bar 131 by a longer distance. At this time, it is also possible to prevent the bending point 113b of the electrode tab 113 of the unit cell 110 (A) shifted closer to the bus bar 131 from coming into contact with the bus bar 131. Therefore, even if the variation in the position of the cell 110 in the direction X intersecting the stacking direction Z is large, the electrode tab 113 and the bus bar 131 can be sufficiently contacted without applying a load to the electrode tab 113. Can be

  In the method of manufacturing the battery pack 100 according to the present embodiment, the laser beam L1 is irradiated toward the convex portion 131b in a state where the tip portion 113c of the electrode tab 113 and the convex portion 131b of the bus bar 131 are in contact with each other. Thereby, the electrode tab 113 and the bus bar 131 are joined.

  According to the method of manufacturing the assembled battery 100 configured as described above, the contact point 131c of the tip portion 113c of the electrode tab 113 in the bus bar 131 can be limited to the position on the protrusion 131b. Then, since the laser beam L1 is emitted toward the convex portion 131b, the contact portion 131c is irradiated with the laser beam L1 regardless of the position of the contact portion 131c on the convex portion 131b. Therefore, even if the position of the contact portion 131c in the convex portion 131b changes due to the variation in the position of the unit cell 110 in the direction X intersecting the stacking direction Z, the electrode tab 113 and the bus bar 131 are connected. Easy and reliable joining.

  As described above, the battery pack 100 has been described through the embodiments. However, the present invention is not limited to the configuration described in the embodiments, and can be appropriately changed based on the description in the claims.

  For example, in the above-described embodiment, the bus bar 131 is attached to the battery group 100G via the bus bar unit 130. However, the bus bar 131 may be directly attached to the battery group 100G without the intervention of the bus bar unit 130. For example, the bus bar 131 can be directly attached to the battery group 100G by a method such as applying an insulating material to a part of the outer peripheral portion of the bus bar 131 and attaching the insulating material to the battery group 100G via the material portion.

  In the battery pack 100 of the above-described embodiment, the connection between the distal end 113c of the electrode tab 113 and the convex portion 131b of the bus bar 131 is performed by laser welding between the distal end 113c of the electrode tab 113 and the convex portion 131b of the bus bar 131. It was made by joining. However, as long as the tip 113c of the electrode tab 113 and the projection 131b of the bus bar 131 are electrically connected, the method of joining the tip 113c of the electrode tab 113 and the projection 131b of the bus bar 131 is not limited.

  Further, in the above-described embodiment, the initial value α1 of the angle α between the base end 113a and the tip 113c, the dimension of the protrusion 131b of the bus bar 131, the dimensions of the base 113a and the tip 113c of the electrode tab 113, and the like. Was determined to satisfy at least the following condition (ii). That is, (ii) in a state where the bus bar 131 is attached to the battery group 100G, the base end portion 113a and the front end portion 113c of the electrode tab 113 of the unit cell 110 (A) shifted to the position closest to the bus bar 131 are formed. The angle α2 was determined to be maintained at 90 ° or more. However, at the angle α2, when the bus bar 131 is attached to the battery group 100G, the bending point 113b of the electrode tab 113 of the unit cell 110 (A) which is shifted to the position closest to the bus bar 131 is pushed by the bus bar 131. It can be changed as long as the condition that there is not is satisfied. For example, the dimensions and the like described above may be determined so that the angle α2 becomes an acute angle.

100 assembled batteries,
100S laminate,
100G battery group,
100M first cell subassembly,
100N second cell subassembly,
110 cells,
110H battery body,
111 power generation elements,
112 laminated film,
112a one end,
112b the other end,
113 electrode tab,
113A anode side electrode tab,
113K cathode side electrode tab,
113a proximal end,
113b bent portion,
113c tip,
113d bending part,
120 a pair of spacers,
121 first spacer,
122 second spacer,
121a laminated reference plane,
130 busbar unit,
131 Busba,
131A anode side bus bar,
131K cathode side bus bar,
131a convex portion,
131b contact point,
131c side,
132 busbar holder,
133 anode side terminal,
134 cathode side terminal,
140 protective cover,
150 housing,
151 upper pressure plate,
152 lower pressure plate,
153 side plate,
160 double-sided tape,
701 mounting table,
705 laser oscillator,
D Distance between busbar and battery body,
L1 laser light,
P base end length,
Q Length of the tip,
R1 Length of convex part,
R2 Length of flexure,
X a longitudinal direction (intersecting with the stacking direction of the cells 110 and of the cells 110);
Y a short direction (intersecting with the stacking direction of the cells 110 and of the cells 110);
Z Lamination direction (of cell 110).

Claims (7)

A flat cell having electrode tabs for transmitting and receiving current, a battery group formed by stacking a plurality of flat cells in the thickness direction thereof,
A plate-shaped bus bar attached to the battery group and electrically connecting the electrode tabs of at least two of the unit cells;
The bus bar has a main portion extending along the stacking direction of the unit cells, and a plurality of protrusions projecting from the main portion toward each of the electrode tabs,
Each of the electrode tabs is connected to a base end extending toward the main part of the bus bar and a base end through a bending point, and intersects a direction in which the base end extends. And a front end portion that extends to contact the corresponding convex portion.   The battery pack according to claim 1, wherein a bending portion that is bent by being relatively pressed between the distal end portion and the convex portion is disposed at the base end portion. Further comprising an insulating spacer for holding the electrode tab,
The battery pack according to claim 1, wherein the protrusion of the bus bar and the spacer are separated from each other with a gap. A flat unit cell including an electrode tab for transmitting and receiving a current, wherein the electrode tab is connected to the base end extending in one direction and the base end via a bending point in the one direction. Preparing a cell having a tip extending in a crossing direction;
A plate-shaped bus bar for electrically connecting the electrode tabs of at least two of the unit cells, wherein a bus bar having a plurality of protrusions protruding from a plate-shaped main portion is prepared.
A plurality of the unit cells are stacked in the thickness direction to form a battery group,
The bus bar is attached to the battery group in a state where the main portion is arranged along the stacking direction of the unit cells, and each of the plurality of protrusions is directed to the corresponding electrode tab. A method for manufacturing an assembled battery, wherein the front end portion of the battery pack is brought into contact with the corresponding convex portion of the bus bar.   The method for manufacturing a battery module according to claim 4, wherein the distal end portion and the convex portion are brought into contact with each other from an obtuse angle formed between the base end portion and the distal end portion.   The method of manufacturing a battery module according to claim 4 or 5, wherein the distal end portion and the convex portion are brought into contact with each other while bending a bending portion formed at the base end portion.   The electrode tab and the bus bar are joined by irradiating a laser beam toward the projection in a state where the tip and the projection are in contact with each other. 13. The method for producing a battery pack according to item 10.