Battery module and battery module manufacturing method

Abstract

A battery module (50) is provided with: a plurality of battery cells (100) stacked in a predetermined direction; and a plurality of lead portions (110) each folded back between at least one battery cell (100) and at least one other battery cell (100). The average inclination of the end surfaces of the plurality of lead portions (110) with respect to a direction perpendicular to the predetermined direction is 85.0 DEG or more and 95.0 DEG or less.

Description

Technical Field

[0001] The present invention relates to a battery module and a method for manufacturing the battery module. Background Art

[0002] A battery module such as a lithium-ion secondary battery has a plurality of stacked battery cells. For example, as described in Patent Document 1, in a part of the battery module, a plurality of battery cells connected in parallel and a plurality of other battery cells connected in parallel are sometimes connected in series via a lead portion. In the battery module, the lead portion is folded back between the plurality of battery cells and the plurality of other battery cells.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2006 / 109610 Summary of the invention

[0006] -Problems to be solved by the invention-

[0007] For example, as described in Patent Document 1, at least one battery cell is sometimes connected in series with at least one other battery cell via a lead portion. In this case, the lead portion is sometimes bent by a single bending process and folded back between the at least one battery cell and the at least one other battery cell. However, when the lead portion is bent by a single bending process, the accuracy and precision of the folded shape of the lead portion is sometimes relatively low.

[0008] One example of the purpose of the present invention is to improve the accuracy and precision of the folded-back shape of the lead portion. Other purposes of the present invention will become clear from the description of this specification.

[0009] -Methods for solving problems-

[0010] One embodiment of the present invention is as follows.

[0011] [1] A battery module comprising: a plurality of battery cells stacked in a given direction; and a plurality of lead portions folded back between at least one battery cell and at least one other battery cell, wherein an average inclination of end faces of the plurality of lead portions relative to a direction perpendicular to the given direction is greater than 85.0° and less than 95.0°.

[0012] [2] A battery module comprising: a plurality of battery cells stacked in a given direction; and a plurality of lead portions folded back between at least one battery cell and at least one other battery cell, wherein a standard deviation of positional offsets of end faces of the plurality of lead portions in a direction perpendicular to the given direction is greater than 0 and less than 2.50 mm.

[0013] [3] A method for manufacturing a battery module, comprising the steps of: bending a portion of a lead portion connecting at least one battery cell and at least one other battery cell; and bending another portion of the lead portion after bending the portion of the lead portion.

[0014] [4] A method for manufacturing a battery module according to [3], wherein the step of bending the portion of the lead portion includes the following step: bending the portion of the lead portion at a bending angle greater than a bending angle of the portion of the lead portion after bending the other portion of the lead portion.

[0015] -Effects of the Invention-

[0016] According to the above aspect of the present invention, the accuracy and precision of the folded-back shape of the lead portion can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a perspective view of the battery module according to the embodiment as viewed from the front.

[0018] Figure 2 is from Figure 1 Figure 2.11: Removal of the container.

[0019] Figure 3 This is a perspective view of a single-unit laminated body according to the embodiment as viewed from the front.

[0020] Figure 4 It is a plan view of a part of the battery module according to the embodiment.

[0021] Figure 5 It is a figure for demonstrating the manufacturing method of the single body laminated body which concerns on embodiment.

[0022] Figure 6 It is a figure for demonstrating the manufacturing method of the single body laminated body which concerns on embodiment.

[0023] Figure 7 It is a figure for demonstrating the manufacturing method of the single body laminated body which concerns on embodiment.

[0024] Figure 8 It is a detailed diagram for explaining a method of bending a lead portion.

[0025] Fig. 9 It is a detailed diagram for explaining a method of bending a lead portion. DETAILED DESCRIPTION

[0026] Hereinafter, the embodiments of the present invention will be described using the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

[0027] In this specification, unless otherwise specified, ordinal numbers such as "first", "second", and "third" are used to simply distinguish structures with the same name, and do not refer to specific features of the structures (for example, order or importance).

[0028] Figure 1 This is a perspective view of the battery module 50 according to the embodiment as viewed from the front. Figure 2 is from Figure 1 FIG. 20 is a diagram in which the housing body 20 is removed. Figure 3 This is a perspective view of the single-body laminated body 10 according to the embodiment as viewed from the front.

[0029] exist Figure 1 to Figure 3 In the figure, the arrows indicating the first direction X, the second direction Y, and the third direction Z indicate that the direction from the base end of the arrow toward the front end is the positive direction of the direction indicated by the arrow, and the direction from the front end of the arrow toward the base end is the negative direction of the direction indicated by the arrow. The first direction X indicates a direction parallel to the horizontal direction perpendicular to the vertical direction. Specifically, the first direction X indicates the front-to-back direction of the battery module 50. The positive direction of the first direction X is the direction from the front to the rear of the battery module 50. The negative direction of the first direction X is the direction from the rear to the front of the battery module 50. The second direction Y indicates a direction perpendicular to the vertical direction and the first direction X. The second direction Y indicates the left-right direction of the battery module 50. The positive direction of the second direction Y is the direction from the right to the left of the battery module 50 when viewed from the front of the battery module 50. The negative direction of the second direction Y is the direction from the left to the right of the single cell stack 10 when viewed from the front of the battery module 50. The third direction Z indicates a direction parallel to the vertical direction. The positive direction of the third direction Z is the direction from the bottom to the top of the battery module 50. The negative direction of the third direction Z is a direction from the upper side to the lower side of the battery module 50 .

[0030] The relationship among the first direction X, the second direction Y, the third direction Z, the vertical direction, and the horizontal direction is not limited to the above-mentioned example. For example, the single laminate 10 may be arranged so that the first direction X or the second direction Y is parallel to the vertical direction.

[0031] Hereinafter, unless otherwise specified, “right” and “left” refer to the right and left, respectively, when viewed from the front of the battery module 50 .

[0032] In the present embodiment, the battery module 50 is mounted on a mobile object such as an automobile, etc. However, the use of the battery module 50 is not limited to this example.

[0033] The battery module 50 includes a cell stack 10, a housing 20, and a voltage detection device 30. The battery module 50 may further include a voltage detection device (not shown) disposed behind the cell stack 10. The voltage detection device disposed behind the cell stack 10 may have, for example, Figure 2 The voltage detection device 30 shown has the same structure.

[0034] use Figure 3 The single-body laminate 10 will be described.

[0035] The cell stack 10 includes a plurality of cell groups 100G. The number of cell groups 100G included in the cell stack 10 is not limited to the following, and is, for example, 2 or more and 30 or less. Each cell group 100G includes a plurality of battery cells 100. Each battery cell 100 includes an exterior member 102, a positive electrode lead 112, and a negative electrode lead 114.

[0036] The exterior member 102 accommodates a battery element (not shown) and an electrolyte solution (not shown). In one example, the battery element includes a positive electrode, a negative electrode, and a separator (not shown) stacked in the second direction Y in the exterior member 102 .

[0037] The positive lead 112 is led out from one of the front end and the rear end of the outer casing 102. The positive lead 112 is electrically connected to the positive electrode in the outer casing 102. In one example, the positive lead 112 contains a metal such as aluminum. The length of the portion of the positive lead 112 led out from the outer casing 102 is not limited to 300 Å, but is, for example, greater than 3 cm and less than 9 cm. The width of the front end of the portion of the positive lead 112 led out from the outer casing 102 is not limited to 300 Å, but is, for example, greater than 3 cm and less than 9 cm. The thickness of the portion of the positive lead 112 led out from the outer casing 102 is not limited to 0.4 mm and less than 0.6 mm.

[0038] The negative lead 114 is led out from the other of the front end and the rear end of the outer casing 102. The negative lead 114 is electrically connected to the negative electrode in the outer casing 102. In one example, the negative lead 114 contains a metal different from the metal constituting the positive lead 112, such as copper. The length of the portion of the negative lead 114 led out from the outer casing 102 is not limited to 300 Å, but is, for example, 3 cm to 9 cm. The width of the front end of the portion of the negative lead 114 led out from the outer casing 102 is not limited to 300 Å, but is, for example, 3 cm to 4.5 cm. The thickness of the portion of the negative lead 114 led out from the outer casing 102 is not limited to 0.2 mm to 0.4 mm.

[0039] In an embodiment, the battery cell 100 has a length direction in the first direction X and a short side direction in the third direction Z. However, the length of the battery cell 100 in the first direction X and the width of the battery cell 100 in the third direction Z may be equal. Alternatively, the battery cell 100 may have a length direction in the third direction Z and a short side direction in the first direction X. The width of the battery cell 100 in the third direction Z is not limited to 0.50 mm / s but is, for example, 8 cm or more and 15 cm or less. The thickness of the battery cell 100 in the second direction Y is not limited to 0.50 mm / s but is, for example, 0.7 cm or more and 1.6 cm or less.

[0040] In each monomer group 100G, a plurality of positive electrode leads 112 included in each monomer group 100G are connected to each other, and a plurality of negative electrode leads 114 included in each monomer group 100G are connected to each other. Thus, in each monomer group 100G, a plurality of battery cells 100 included in each monomer group 100G are connected in parallel. In an embodiment, each monomer group 100G includes 2 battery cells 100. However, the number of battery cells 100 included in each monomer group 100G may be more than 3. Alternatively, the number of battery cells 100 included in each monomer group 100G may be only one. In other words, the monomer group 100G may also be a battery cell 100.

[0041] Hereinafter, the plurality of positive electrode leads 112 included in each cell group 100G will be referred to as a positive electrode lead group 112G as needed. Also, the plurality of negative electrode leads 114 included in each cell group 100G will be referred to as a negative electrode lead group 114G as needed.

[0042] The plurality of cell groups 100G are connected in series via a plurality of lead portions 110 .

[0043] Each lead portion 110 includes one positive lead group 112G of the cell group 100G adjacent to each other in the second direction Y and another negative lead group 114G of the cell group 100G adjacent to each other in the second direction Y. The positive lead group 112G and the negative lead group 114G are joined to each other by a joining method such as laser welding, ultrasonic joining, resistance welding, or bonding. When the material of the positive lead 112 is different from that of the negative lead 114, laser welding is preferred among these joining methods from the viewpoint of high reliability of joining and reduction in the number of components.

[0044] In the monomer stack 10, the monomer group 100G in which the positive lead group 112G is located on the front side and the negative lead group 114G is located on the rear side, and the monomer group 100G in which the positive lead group 112G is located on the rear side and the negative lead group 114G is located on the front side are alternately stacked in the second direction Y. Each lead portion 110 is folded back between the monomer groups 100G adjacent to each other in the second direction Y. Thus, in front of the monomer stack 10, a plurality of lead portions 110 are arranged in the second direction Y. In addition, in the rear of the monomer stack 10, a plurality of lead portions 110 are also arranged in the second direction Y. The plurality of lead portions 110 arranged along the second direction Y in front of the monomer stack 10 and the plurality of lead portions 110 arranged along the second direction Y in the rear of the monomer stack 10 are alternately arranged in the second direction Y.

[0045] use Figure 1 as well as Figure 2 The housing 20 will be described.

[0046] The housing 20 houses the cell stack 10 and the voltage detection device 30 . The housing 20 includes a first cover member 210 , a second cover member 220 , a third cover member 230 , a fourth cover member 240 , a fifth cover member 250 , and a sixth cover member 260 .

[0047] The first cover member 210 covers the front side of the monomer stack 10 and the voltage detection device 30. The second cover member 220 covers the rear side of the monomer stack 10. In addition, in the case where a voltage detection device (not shown) is provided behind the monomer stack 10, the second cover member 220 may also cover the voltage detection device. The third cover member 230 covers the right side of the monomer stack 10. The fourth cover member 240 covers the left side of the monomer stack 10. The fifth cover member 250 covers the lower side of the monomer stack 10. The sixth cover member 260 covers the upper side of the monomer stack 10. The third cover member 230 and the fourth cover member 240 are parallel to the first direction X.

[0048] use Figure 2 The voltage detection device 30 will be described.

[0049] The voltage detection device 30 includes a holding body 300 , a plurality of voltage detection units 310 , a plurality of voltage detection lines 320 , and a connector 330 .

[0050] The holding body 300 is provided in front of the single-unit stack 10. The holding body 300 is attached to the housing 20 by mechanical fastening such as snaps or screws.

[0051] The plurality of voltage detection units 310 are respectively held by the holding body 300 . In addition, the plurality of voltage detection units 310 are respectively connected to the plurality of lead units 110 at the front of the single-unit laminated body 10 .

[0052] The plurality of voltage detection lines 320 electrically connect the plurality of voltage detection units 310 to the connectors 330. In the embodiment, the connector 330 is provided on the upper portion of the holding body 300. However, the position of the voltage detection unit 310, the wiring of the voltage detection line 320, and the position of the connector 330 are not limited to the example involved in the embodiment.

[0053] Figure 4 It is a plan view of a part of the battery module 50 according to the embodiment.

[0054] exist Figure 4 In the figure, the white circle with a black dot representing the third direction Z indicates that the direction from the back side to the front side of the paper is the positive direction of the third direction Z, and the direction from the front side to the back side of the paper is the negative direction of the third direction Z.

[0055] exist Figure 4 In the following, the lead portion 110 on the front side of the single laminated body 10 will be described. Figure 4 The matters described in can also be applied to the lead portion 110 on the rear side of the single laminated body 10 .

[0056] The positive lead group 112G is led out toward the front of the battery cell 100. The positive lead group 112G is bent at the positive bent portion 112a. Thus, the front end of the positive lead group 112G is bent toward the negative direction of the second direction Y.

[0057] The negative electrode lead group 114G is led out toward the front of the single laminate 10. The negative electrode lead group 114G is bent at the negative electrode bent portion 114a. Thus, the front end of the negative electrode lead group 114G is bent toward the positive direction of the second direction Y.

[0058] At least a portion of the bent front end of the positive lead group 112G overlaps with at least a portion of the bent front end of the negative lead group 114G in the first direction X. Figure 4 In the example shown, the bent front end of the negative lead group 114G is located further forward of the single laminate 10 than the bent front end of the positive lead group 112G. The length between the positive bent portion 112a and the negative bent portion 114a of the lead portion 110 is not limited to 0.6 cm or more and 4.0 cm or less, for example. The length of the overlapping portion of the positive lead group 112G and the negative lead group 114G between the positive bent portion 112a and the negative bent portion 114a in the second direction Y is not limited to 0.7 cm or more and 6.4 cm or less, for example.

[0059] The rear surface of the voltage detection part 310 is joined to the front surface of the bent front end of the negative lead group 114G by a joining method such as laser welding. The rear surface of the voltage detection part 310 preferably contains the same material as the portion of the lead part 110 to which the voltage detection part 310 is joined. Figure 4 In the example shown, the rear surface of the voltage detection portion 310 preferably includes the same material as the front surface of the bent front end of the negative lead group 114G.

[0060] exist Figure 4 In FIG. 1 , for the sake of explanation, a reference plane R is virtually shown by a dotted line. The reference plane R is a plane orthogonal to the first direction X. Figure 4 In the illustrated example, the reference plane R passes between the front surface of the bent front end of the positive electrode lead group 112G and the rear surface of the bent front end of the negative electrode lead group 114G.

[0061] In the embodiment, the average inclination of the front end surfaces of the plurality of lead portions 110 relative to the first direction X is 90° or a value close to 90°. Therefore, the accuracy and precision of the bent shape of the lead portion 110 are relatively high. Figure 4 In the illustrated example, the front end surface of the lead portion 110 is the front surface of the bent front end of the negative electrode lead group 114G.

[0062] In the embodiment, the average inclination of the end surface of the front side of the plurality of lead portions 110 with respect to the first direction X is, for example, 85.0° or more and 95.0° or less. The lower limit of the average is, for example, preferably 86.0°, more preferably 87.5°, and further preferably 89.0°. The upper limit of the average is, for example, preferably 94.0°, more preferably 92.5°, and further preferably 91.0°.

[0063] In the embodiment, the maximum value of the inclination of the front end surfaces of the plurality of lead portions 110 with respect to the first direction X is, for example, 97.5° or less, preferably 95.0° or less, and more preferably 92.5° or less.

[0064] In the embodiment, the minimum value of the inclination of the front end surfaces of the plurality of lead portions 110 with respect to the first direction X is, for example, 87.5° or more, preferably 88.0° or more, and more preferably 88.5° or more.

[0065] The average of the inclinations of the end faces on the front side of the plurality of lead portions 110 with respect to the first direction X is calculated, for example, with reference to all the lead portions 110 provided in front of the single laminate 10. Alternatively, the average may be calculated with reference to the above-mentioned upper given number of lead portions 110 with the smallest inclination among all the lead portions 110 provided in front of the single laminate 10. The given number is, for example, 50% or more, 60% or more, or 75% of all the lead portions 110 provided in front of the single laminate 10. The same is true for the standard deviation of the inclinations of the end faces on the front side of the plurality of lead portions 110 with respect to the first direction X.

[0066] In the embodiment, the standard deviation of the positional deviation of the front end surfaces of the plurality of lead portions 110 in the first direction X is 0 or relatively small. Therefore, the accuracy and precision of the bent shape of the lead portion 110 becomes relatively high. Figure 4 In the illustrated example, the front end surface of the lead portion 110 is the front surface of the bent front end of the negative electrode lead group 114G.

[0067] In the embodiment, the standard deviation of the positional deviations of the front end surfaces of the plurality of lead portions 110 in the first direction X is, for example, 2.50 mm or less, preferably 2.00 mm or less, and more preferably 1.00 mm or less.

[0068] The length in the first direction X from the end surface of the lead portion 110 on the front side of the cell stack 10 to the end surface of the lead portion 110 on the rear side of the cell stack 10 is not limited to the following, but is, for example, 35 cm to 80 cm. The deviation of this length among the plurality of battery cells 100 is, for example, within ±2 mm, preferably within ±1 mm.

[0069] The standard deviation of the positional deviation of the end faces of the front side of the plurality of lead portions 110 in the first direction X is calculated, for example, with reference to all the lead portions 110 provided in the front of the single laminated body 10. Alternatively, the standard deviation may be calculated with reference to the upper given number of lead portions 110 with the smaller deviation among all the lead portions 110 provided in the front of the single laminated body 10. The given number is, for example, 50% or more, 60% or more, or 75% of all the lead portions 110 provided in the front of the single laminated body 10.

[0070] The standard deviation of the displacement of the position of the end surface of the front side of the plurality of lead portions 110 in the first direction X is calculated, for example, by measuring the displacement of the position of the end surface of the front side of the lead portion 110 relative to the first direction X of the reference plane R. Alternatively, the standard deviation can also be calculated by measuring the displacement of the position of the end surface of the front side of the lead portion 110 relative to the first direction X of the surface parallel to the reference plane R. The reference plane R is arbitrarily set perpendicular to the first direction X so as to pass through the joint portion of the front surface of the bent front end of the positive lead group 112G and the rear surface of the bent front end of the negative lead group 114G. Alternatively, the displacement of the length in the first direction X from the end surface of the lead portion 110 on the front side of the single laminate 10 to the end surface of the lead portion 110 on the rear side of the single laminate 10 can also be measured to calculate. This length is a length parallel to the X direction. In addition, when at least one of the two end faces mentioned above is inclined relative to the second direction Y when viewed from the third direction Z, the length can be the maximum value of the length in the first direction X from the end face of the lead portion 110 on the front side of the monomer stack 10 to the end face of the lead portion 110 on the rear side of the monomer stack 10.

[0071] In addition, Figure 4 Schematically depicting the positive electrode lead 112 and the negative electrode lead 114 led out from two battery cells 100 of the cell group 100G and linearly approaching the vicinity of the reference plane R. However, the positive electrode lead 112 and the negative electrode lead 114 may be bent in the middle.

[0072] Figure 5 to Figure 7 1 is a diagram for explaining a method for manufacturing a single layer stack 10 according to an embodiment. Figure 5 to Figure 7 In the figure, the direction from the back side toward the front of the paper becomes the direction from the bottom to the top in the vertical direction, and the direction from the front to the back side of the paper becomes the direction from the top to the bottom in the vertical direction.

[0073] exist Figure 5 to Figure 7 In the description of Figure 5 to Figure 7 Of the two cell groups 100G shown, the cell group 100G provided with the positive electrode lead group 112G is referred to as the cell group 100G on the positive electrode lead group 112G side as required. Figure 5 to Figure 7 In the description of Figure 5 to Figure 7 Of the two cell groups 100G shown, the cell group 100G provided with the negative electrode lead group 114G is referred to as a cell group 100G on the negative electrode lead group 114G side as necessary.

[0074] The single body laminated body 10 according to the embodiment is produced as follows.

[0075] First, a plurality of cell groups 100G are formed. In each cell group 100G, a plurality of battery cells 100 are stacked. In the embodiment, each cell group 100G includes two stacked battery cells 100. However, the number of battery cells 100 included in each cell group 100G is not limited to two, and may be three or more.

[0076] In addition, Figure 5 to Figure 7 In the description, the case where the cell groups 100G are connected in series through the lead portion 110 is described. Figure 5 to Figure 7 The matters described in the above are also applicable to a case where a single battery cell 100 is connected in series with another single battery cell 100 via the lead portion 110 .

[0077] Next, multiple monomer groups 100G are arranged. Figure 5 As shown, in adjacent cell groups 100G, at least a portion of the positive lead group 112G overlaps with at least a portion of the negative lead group 114G. Next, between adjacent cell groups 100G, at least a portion of the positive lead group 112G and at least a portion of the negative lead group 114G are joined by a joining method such as laser welding.

[0078] Next, if Figure 6 As shown in FIG. 1 , a portion of the lead portion 110 is bent. Figure 6 In the example shown, the negative electrode lead group 114G is bent. Figure 7 As shown in FIG. 1 , another portion of the lead portion 110 is bent. Figure 7 In the example shown, the positive electrode lead group 112G is bent. Thus, in the embodiment, when the lead portion 110 is folded back between adjacent cell groups 100G, the lead portion 110 is bent in two stages. Figure 6 as well as Figure 7 In the example shown, if you use Figure 8 as well as Fig. 9 As will be described later, the lead portion 110 is bent using a jig 510 .

[0079] right Figure 6 as well as Figure 7 The bending of the lead portion 110 will be described in detail.

[0080] First, if Figure 6 As shown in FIG. 1 , the cell group 100G on the negative lead group 114G side is rotated around the negative bent portion 114a. Thus, the negative lead group 114G is bent at a temporary bending angle θ′. Considering the springback of the negative lead group 114G, the temporary bending angle θ′ is larger than the angle described later. Figure 7 Therefore, even if the temporary refraction angle θ′ of the negative lead group 114G is Figure 6After the process shown in the figure, the springback is reduced, and the negative lead group 114G can also be obtained. Figure 7 The desired refraction angle θ is shown. The temporary bending angle θ′ is, for example, greater than 90°. The upper limit of the temporary bending angle θ′ is not limited to the following, and is, for example, 100° or 95°.

[0081] When the negative lead group 114G contains copper, the springback of the negative lead group 114G tends to be larger than when the negative lead group 114G contains a metal different from copper. In the embodiment, even when the springback of the negative lead group 114G is relatively large, the accuracy and precision of the folded shape of the lead portion 110 can be relatively high.

[0082] When the lead portion 110 is folded back between adjacent cell groups 100G, it is assumed that the lead portion 110 is not folded in two stages but folded once, and the negative lead group 114G is folded back in a shorter distance than the negative lead group 114G in consideration of the springback of the negative lead group 114G. Figure 7 In the embodiment, the negative lead group 114G is bent at a larger bending angle than the case where the lead portion 110 is bent once, taking into account the springback of the negative lead group 114G. Figure 7 The desired bending angle θ shown in FIG. 1 is large, and pre-bending becomes easy.

[0083] in addition, Figure 6 The temporary bending angle θ′ shown and Figure 7 The desired bending angle θ shown is the angle between the lead portion 110 after the negative lead group 114G is bent and the lead portion 110 before the negative lead group 114G is bent. Figure 5 The angle formed by the lead portion 110 is shown.

[0084] Next, if Figure 7 As shown, in a state where the bending angle of the negative lead group 114G is set to a desired bending angle θ, the cell group 100G on the positive lead group 112G side is rotated around the positive bent portion 112a. As a result, the positive lead group 112G is bent, and the cell group 100G on the positive lead group 112G side is stacked on the cell group 100G on the negative lead group 114G side. Figure 7 In the example shown, the desired refraction angle θ is a right angle.

[0085] The lead portion 110 located between adjacent cell groups 100G in the plurality of cell groups 100G is used as follows. Figure 5 to Figure 7 The monomer groups 100G are sequentially stacked in this way. In this way, the monomer stack 10 is manufactured.

[0086] In the embodiment, as described above, when the lead portion 110 is folded back between adjacent cell groups 100G, the lead portion 110 is folded in two stages. Therefore, compared with the case where the lead portion 110 is folded back once when the lead portion 110 is folded back between adjacent cell groups 100G, it is easier to control the curvature of the lead portion 110 in the positive electrode bent portion 112a and the curvature of the lead portion 110 in the negative electrode bent portion 114a.

[0087] The method for manufacturing the single layer stack 10 is not limited to Figure 5 to Figure 7 The method shown. For example, the positive lead group 112G may be bent, and then the negative lead group 114G may be bent. Specifically, the cell group 100G on the positive lead group 112G side is rotated around the positive bent portion 112a. Thus, the positive lead group 112G is bent at a temporary bending angle larger than the desired refraction angle in consideration of the rebound of the positive lead group 112G. Next, in a state where the bending angle of the positive lead group 112G is set to the desired bending angle, the cell group 100G on the negative lead group 114G side is rotated around the negative bent portion 114a. Thus, the negative lead group 114G is bent, and the cell group 100G on the negative lead group 114G side is stacked on the cell group 100G on the positive lead group 112G side. In addition, in Figure 5 to Figure 7 In the example shown, the monomer group 100G on the negative lead group 114G side is rotated to form the negative bent portion 114a. However, the monomer group 100G on the positive lead group 112G side may be rotated to form the negative bent portion 114a. In addition, in the above example, the negative lead group 114G or the positive lead group 112G is bent at a temporary bending angle. However, the negative lead group 114G or the positive lead group 112G may be bent at a desired bending angle instead of the negative lead group 114G or the positive lead group 112G being bent at a temporary bending angle.

[0088] Figure 8 as well as Fig. 9 It is a detailed diagram for explaining a method of bending the lead portion 110 .

[0089] exist Figure 8 as well as Fig. 9 In the example shown, the lead portion 110 is bent using a jig 510. The jig 510 includes a center clamp 512, a positive electrode clamp 514, and a negative electrode clamp 516.

[0090] like Figure 8 As shown, the central clamp 512 holds the overlapping portion of the front end of the positive lead group 112G and the front end of the negative lead group 114G. That is, the clamp 510 is a holding portion that holds at least a portion of the lead portion 110.

[0091] like Figure 8As shown, the positive electrode clamp 514 grips the positive lead 112 of the cell group 100G on the positive lead group 112G side. The positive electrode clamp 514 is roughly V-shaped. Specifically, the surface of the positive electrode clamp 514 on the outer casing 102 side is shaped to cover the front end of the outer casing 102 of the cell group 100G on the positive lead group 112G side with a gap. Therefore, it is possible to make it difficult for the surface of the positive electrode clamp 514 to contact the outer casing 102. As a result, the positive electrode clamp 514 can reliably grip the portion of the positive lead 112 near the outer casing 102. For example, the positive electrode clamp 514 grips the positive lead 112 at a position that is 1.5 mm or more and less than 5.0 mm away from the end of the outer casing 102, preferably at a position that is 2.0 mm or more and 3.5 mm or less away. In this example, compared with the case where the positive electrode clamp 514 holds the positive electrode lead 112 at a position closer to the end of the outer member 102 than the above range, damage to the positive electrode lead 112 and the sealing portion of the outer member 102 can be suppressed. In addition, in the above example, compared with the case where the positive electrode clamp 514 holds the positive electrode lead 112 at a position farther from the end of the outer member 102 than the above range, the accuracy of bending the positive electrode lead 112 can be improved. The positive electrode clamp 514 is directly or indirectly attached to a cell fixing portion that fixes a cell group 100G (not shown). Therefore, the positive electrode clamp 514 does not rotate relative to the outer member 102 of the battery cell 100. As a result, even when the positive electrode clamp 514 is rotated relative to the central clamp 512, the cell group 100G rotates integrally with the positive electrode lead group 112G near the outer member 102. Therefore, bending of the positive electrode lead 112 located inside the outer member 102 can be prevented. In addition, the inclination of the end surface of the lead portion 110 after the lead portion 110 is bent relative to the reference plane R can be reduced. Furthermore, the force applied to the portion of the positive lead 112 sandwiched by the exterior member 102 can be suppressed. Therefore, damage to the exterior member 102 can be prevented, and the connection portion between the battery element (not shown) and the positive lead 112 can be prevented from being broken.

[0092] The negative electrode clamp 516 has the same structure as the positive electrode clamp 514. Figure 8As shown, the negative electrode clamp 516 holds the negative electrode lead 114 of the cell group 100G on the negative electrode lead group 114G side. For example, the negative electrode clamp 516 holds the negative electrode lead 114 at a position that is 1.5 mm or more and less than 5.0 mm away from the end of the exterior member 102, preferably at a position that is 2.0 mm or more and 3.5 mm or less away. In this example, compared with a case where the negative electrode clamp 516 holds the negative electrode lead 114 at a position that is closer to the end of the exterior member 102 than the above range, damage to the negative electrode lead 114 and the sealing portion of the exterior member 102 can be suppressed. In addition, in the above example, compared with a case where the negative electrode clamp 516 holds the negative electrode lead 114 at a position that is farther from the end of the exterior member 102 than the above range, the accuracy of bending the negative electrode lead 114 can be improved. The negative electrode clamp 516 is also directly or indirectly attached to a cell fixing portion that fixes the cell group 100G (not shown). Therefore, the negative electrode clamp 516 does not rotate relative to the exterior member 102 of the battery cell 100 .

[0093] Next, if Fig. 9 As shown, the negative clamp 516 is rotated relative to the central clamp 512. As a result, the negative lead group 114G is bent around the negative bent portion 114a. Figure 6 As described above, the negative lead group 114G is bent at a temporary bending angle θ′ larger than 90° in consideration of the springback of the negative lead group 114G.

[0094] Next, the positive electrode clamp 514 is rotated relative to the center clamp 512. As a result, the positive electrode lead group 112G is bent around the positive electrode bent portion 112a.

[0095] exist Figure 8 as well as Fig. 9 In the bending of the lead portion 110 shown, it is preferable that the rotation axis of the bending of the negative electrode lead group 114G and the rotation axis of the bending of the positive electrode lead group 112G are different.

[0096] In addition, Figure 8 as well as Fig. 9 In the example shown, the negative bent portion 114a is formed by rotating the cell group 100G on the negative lead group 114G side, but the negative bent portion 114a may be formed by rotating the cell group 100G on the positive lead group 112G side.

[0097] Example

[0098] Hereinafter, the monomer stack 10 according to the embodiment will be specifically exemplified in the examples. In addition, the monomer stack 10 according to the embodiment is not limited to the monomer stack 10 described in the examples.

[0099] (Example 1)

[0100] The single-body laminated body 10 according to Example 1 was produced as follows.

[0101] 20 monomer groups 100G are manufactured. Each monomer group 100G includes two battery cells 100. Two positive electrode leads 112 are led out from one end of the outer casing 102 of each monomer group 100G. Two negative electrode leads 114 are led out from the other end of the outer casing 102 of each monomer group 100G. Each positive electrode lead 112 is set as an aluminum lead. The length of the portion of the positive electrode lead 112 led out from the outer casing 102, the width of the front end and the thickness are 3 cm, 4.5 cm and 0.4 mm, respectively. Each negative electrode lead 114 is set as a copper lead. The length of the portion of the negative electrode lead 114 led out from the outer casing 102, the width of the front end and the thickness are 3 cm, 4.5 cm and 0.2 mm, respectively. The length of each battery cell 100 excluding the positive electrode lead 112 and the negative electrode lead 114 is 55 cm. The width of each battery cell 100 is 59 cm. The thickness of each battery cell 100 was set to 0.8 cm.

[0102] Next, these monomer groups 100G are arranged. Figure 5 As shown in FIG. 1 , a portion of the positive lead group 112G and a portion of the negative lead group 114G are overlapped between adjacent cell groups 100G. Next, the portion of the positive lead group 112G and the portion of the negative lead group 114G are joined by laser welding. The length of the overlapping portion of the positive lead group 112G and the negative lead group 114G in the direction from one side of the adjacent cell groups 100G toward the other side is 1 cm.

[0103] Next, if Figure 6 As shown in FIG. 1 , the cell group 100G on the negative lead group 114G side is rotated around the negative bent portion 114a. Thus, the negative lead group 114G is bent at 90 degrees. Figure 8 as well as Fig. 9 During the bending of the negative lead group 114G, the negative lead group 114G is gripped by the negative clamp 516 at a position 2.0 mm to 3.5 mm away from the end of the exterior member 102 .

[0104] Next, if Figure 7 As shown in FIG. 1 , the cell group 100G on the positive lead group 112G side is rotated around the positive bent portion 112a while the bending angle θ of the negative lead group 114G is set at a right angle. Thus, the positive lead group 112G is bent, and the cell group 100G on the positive lead group 112G side is stacked on the cell group 100G on the negative lead group 114G side. When the positive lead group 112G is bent, the cell group 100G on the positive lead group 112G side is stacked on the cell group 100G on the negative lead group 114G side. Figure 8 as well as Fig. 9The clamp 510 is shown. When the positive lead group 112G is bent, the positive lead group 112G is held by the positive clamp 514 at a position 2.0 mm to 3.5 mm away from the end of the exterior member 102. The length between the positive bent portion 112a and the negative bent portion 114a of the lead portion 110 is 1 cm from the positive bent portion 112a to the negative bent portion 114a.

[0105] The lead portions 110 located between adjacent monomer groups 100G among the plurality of monomer groups 100G are bent in sequence according to the above method. Thus, the plurality of monomer groups 100G are stacked in sequence. The length from the position of the end face of the lead portion 110 on the front side of the monomer stack 10 to the position of the end face of the lead portion 110 on the rear side of the monomer stack 10 is 550 mm. In this way, the monomer stack 10 involved in Example 1 is manufactured.

[0106] (Example 2)

[0107] The monomer laminated body according to Example 2 was produced in the same manner as the monomer laminated body according to Example 1 except for the following points.

[0108] In Example 2, Figure 6 As shown, the cell group 100G on the negative lead group 114G side is rotated around the negative bent portion 114a. Thus, the negative lead group 114G is bent at a temporary bending angle θ′ (95°) greater than 90°. Figure 8 as well as Fig. 9 During the bending of the negative lead group 114G, the negative lead group 114G is gripped by the negative clamp 516 at a position 2.0 mm to 3.5 mm away from the end of the exterior member 102 .

[0109] Next, if Figure 7 As shown in FIG. 1 , the cell group 100G on the positive lead group 112G side is rotated around the positive bent portion 112a while the bending angle θ of the negative lead group 114G is set at a right angle. Thus, the positive lead group 112G is bent, and the cell group 100G on the positive lead group 112G side is stacked on the cell group 100G on the negative lead group 114G side. When the positive lead group 112G is bent, the cell group 100G on the positive lead group 112G side is stacked on the cell group 100G on the negative lead group 114G side. Figure 8 as well as Fig. 9 During the bending of the positive electrode lead group 112G, the positive electrode clamp 514 holds the positive electrode lead group 112G at a position 2.0 mm to 3.5 mm away from the end of the exterior member 102 .

[0110] The lead portions 110 located between adjacent cell groups 100G among the plurality of cell groups 100G are bent sequentially in the above-described method. Thus, the plurality of cell groups 100G are sequentially stacked. In this way, the cell stack 10 according to Example 2 is manufactured.

[0111] (Example 3)

[0112] Example 3 is the same as Example 2 except that the length from the end surface of the lead portion 110 on the front side of the unit laminate 10 to the end surface of the lead portion 110 on the rear side of the unit laminate 10 is set to 350 mm.

[0113] (Example 4)

[0114] Example 4 is the same as Example 1 except that the length from the end surface of the lead portion 110 on the front side of the cell stack 10 to the end surface of the lead portion 110 on the rear side of the cell stack 10 is set to 350 mm and 10 cell groups 100G each including 20 battery cells 100 are manufactured.

[0115] (Comparative Example)

[0116] The monomer laminated body 10 according to the comparative example was produced in the same manner as the monomer laminated body 10 according to Example 1 except for the following points.

[0117] In the comparative example, Figure 5 As shown, after a part of the positive lead group 112G and a part of the negative lead group 114G are joined, the cell group 100G on the positive lead group 112G side is rotated relative to the cell group 100G on the negative lead group 114G side by a single bending process, and the cell group 100G on the positive lead group 112G side is stacked on the cell group 100G on the negative lead group 114G side. In other words, in the comparative example, the bending process of rotating the cell group 100G on the positive lead group 112G side around the negative bent portion 114a and the bending process of rotating the cell group 100G on the positive bent portion 112a side around the positive bent portion 112a are not performed.

[0118] Table 1 shows the average of the inclinations of the end faces of the plurality of lead portions 110 relative to the direction perpendicular to the stacking direction of the plurality of cell groups 100G for Examples 1 to 4 and the comparative example. In Table 1, the numerical value in the column of "Average (°)" indicates the average of the inclination (unit: °). The numerical value in the column of "Maximum (°)" indicates the maximum value of the inclination (unit: °). The numerical value in the column of "Minimum (°)" indicates the minimum value of the inclination (unit: °).

[0119] [Table 1]

[0120]

[0121] In Examples 1 to 4 and the comparative example, the average of the above-mentioned inclination is calculated with reference to all the lead portions 110 provided in front of the cell stack 10. In calculating the average, the above-mentioned inclination with respect to the length direction of the battery cell 100 is measured. The length direction of the battery cell 100 is Figure 4 The first direction X in the example shown. In Examples 1 to 4, the average of the above-mentioned inclination is 85.0° or more and 95.0° or less. In Examples 1 to 4, the maximum value of the above-mentioned inclination is 97.5° or less. In Examples 1 to 4, the minimum value of the above-mentioned inclination is 87.5° or more.

[0122] Table 2 shows the standard deviation of the positional deviation of the end faces of the plurality of lead portions 110 in the direction perpendicular to the stacking direction of the plurality of cell groups 100G for Examples 1 to 4 and the comparative example. In Table 2, the numerical value in the column “Standard Deviation (mm)” indicates the standard deviation (unit: mm).

[0123] [Table 2]

[0124]

[0125] In Examples 1 to 4 and the comparative example, the standard deviation is calculated with reference to all the lead portions 110 provided in front of the cell stack 10. In calculating the standard deviation, the deviation in the length direction of the battery cell 100 is measured. The length direction of the battery cell 100 is Figure 4 The first direction X in the example shown. In Examples 1 to 4, the standard deviation is greater than or equal to 0 and less than or equal to 2.50 mm.

[0126] Based on the comparison between Examples 1 to 4 and the comparative example, it can be said that when the lead portion 110 is bent in two stages when folding back between adjacent monomer groups 100G, the accuracy and precision of the folded shape of the lead portion 110 can be improved compared to the case where the lead portion 110 is bent once when folding back between adjacent monomer groups 100G.

[0127] As mentioned above, although embodiment and Example of this invention were described with reference to drawings, these are illustrations of this invention, and various structures other than the above-mentioned can also be adopted.

[0128] This application claims the benefit of priority based on Japanese patent application No. 2022-111633, filed on July 12, 2022, the disclosure of which is incorporated herein in its entirety.

[0129] -Description of Reference Numerals-

[0130] 10: Cell stack, 20: Housing, 30: Voltage detection device, 50: Battery module, 100: Battery cell, 100G: Cell group, 102: External component, 110: Lead portion, 112: Positive electrode lead, 112G: Positive electrode lead group, 112a: Positive electrode bent portion, 114: Negative electrode lead, 114G: Negative electrode lead group, 114a: Negative electrode bent portion, 210: First cover member, 220 : second cover member, 230: third cover member, 240: fourth cover member, 250: fifth cover member, 260: sixth cover member, 300: holding body, 310: voltage detection unit, 320: voltage detection line, 330: connector, 510: clamp, 512: central clamp, 514: positive electrode clamp, 516: negative electrode clamp, R: reference plane, X: first direction, Y: second direction, Z: third direction.

Claims

1. A battery module, characterized in that: have: A plurality of battery cells stacked in a given direction; and A plurality of lead portions are respectively folded back between at least one battery cell and at least one other battery cell, An average of inclinations of the end surfaces of the plurality of lead portions with respect to a direction perpendicular to the given direction is greater than or equal to 85.0° and less than or equal to 95.0°.

2. A battery module, characterized in that: have: A plurality of battery cells stacked in a given direction; and A plurality of lead portions are respectively folded back between at least one battery cell and at least one other battery cell, A standard deviation of displacements of the positions of the end surfaces of the plurality of lead portions in a direction perpendicular to the given direction is greater than or equal to 0 and less than or equal to 2.50 mm.

3. A method for manufacturing a battery module, characterized in that: The following processes are available: bending a portion of a lead portion connecting at least one battery cell and at least one other battery cell; and After the part of the lead portion is bent, another part of the lead portion is bent.

4. The method for manufacturing a battery module according to claim 3, wherein: The step of bending the part of the lead portion includes the step of bending the part of the lead portion at a greater bending angle than a bending angle of the part of the lead portion after the other part of the lead portion is bent.

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