Battery module manufacturing method

Abstract

To increase the degree of accuracy and the precision of a folding shape of a lead part.SOLUTION: A battery module 50 includes a plurality of battery cells 100 stacked in a predetermined direction, and a plurality of lead parts 110 that are folded between at least one of the battery cells 100 and at least another one of the battery cells 100. The average tilt of end faces of the lead parts 110 with respect to a direction perpendicular to the predetermined direction is 85.0° or more and 95.0° or less.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] A battery module such as a lithium-ion secondary battery includes a plurality of stacked battery cells. For example, as described in Patent Document 1, some battery modules may have a plurality of battery cells connected in parallel connected in series with a plurality of other battery cells connected in parallel by lead portions. In this battery module, the lead portions are folded back between the plurality of battery cells and the plurality of other battery cells. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2006 / 109610 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, as described in Patent Document 1, at least one battery cell and at least one other battery cell may be connected in series by a lead portion. In this case, the lead portion may be bent in 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 in a single bending process, the accuracy and precision of the folded shape of the lead portion may be relatively low.

[0005] One object of the present invention is to improve the accuracy and precision of the folded shape of the lead portion. Other objects of the present invention will become apparent from the description of this specification. [Means for solving the problem]

[0006] One aspect of the present invention is as follows. [1] a plurality of battery cells stacked in a predetermined direction; a plurality of lead portions each folded between at least one battery cell and at least one other battery cell; Equipped with a battery module in which the average inclination of the end faces of the plurality of lead portions with respect to the direction perpendicular to the predetermined direction is 85.0° or more and 95.0° or less. [2] a plurality of battery cells stacked in a predetermined direction; a plurality of lead portions each folded between at least one battery cell and at least one other battery cell; Equipped with A battery module in which the standard deviation of the positional deviation of the end faces of the plurality of lead portions in a direction perpendicular to the predetermined direction is 0 to 2.50 mm. [3] bending a portion of a lead connecting at least one battery cell to at least one other battery cell; bending another portion of the lead portion after bending the portion of the lead portion; A method for manufacturing a battery module comprising: [4] [3] A method for manufacturing a battery module according to the present invention, wherein the step of bending the portion of the lead portion includes a step of bending the portion of the lead portion at a bending angle greater than the bending angle of the portion of the lead portion after the other portion of the lead portion is bent. [Effects of the Invention]

[0007] According to the above aspect of the present invention, the accuracy and precision of the folded shape of the lead portion can be increased. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a front perspective view of the battery module according to the embodiment. [Figure 2] FIG. 2 is a view of FIG. 1 with the container removed. [Figure 3] FIG. 2 is a perspective view of the cell stack according to the embodiment, as seen from the front. [Figure 4] FIG. 2 is a top view of a portion of the battery module according to the embodiment. [Figure 5] 1A to 1C are diagrams for explaining a method for manufacturing a cell stack according to an embodiment. [Figure 6] 1A to 1C are diagrams for explaining a method for manufacturing a cell stack according to an embodiment. [Figure 7] 1A to 1C are diagrams for explaining a method for manufacturing a cell stack according to an embodiment. [Figure 8] 10A and 10B are diagrams for explaining details of a method for bending a lead portion. [Figure 9] 10A and 10B are diagrams for explaining details of a method for bending a lead portion. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar components are designated by similar reference numerals, and the description thereof will be omitted as appropriate.

[0010] In this specification, ordinal numbers such as "first," "second," and "third" are used merely to distinguish between similarly named configurations, unless otherwise specified, and do not imply any particular characteristics (e.g., order or importance) of the configurations.

[0011] Fig. 1 is a perspective view of a battery module 50 according to an embodiment, as seen from the front. Fig. 2 is a view of Fig. 1 from which a housing 20 has been removed. Fig. 3 is a perspective view of a cell stack 10 according to an embodiment, as seen from the front.

[0012] 1 to 3, 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 to the tip end is the positive direction of the arrow, and the direction from the tip end of the arrow to the base end is the negative direction of 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-rear 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-to-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 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 below to above the battery module 50. The negative direction of the third direction Z is the direction from above to below the battery module 50.

[0013] The relationship between 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 example. For example, the cell stack 10 may be arranged so that the first direction X or the second direction Y is parallel to the vertical direction.

[0014] Hereinafter, unless otherwise specified, "right" and "left" refer to the right and left, respectively, when viewed from the front of the battery module 50.

[0015] In this 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.

[0016] 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) provided behind the cell stack 10. The voltage detection device provided behind the cell stack 10 has, for example, the same configuration as the voltage detection device 30 shown in FIG. 2.

[0017] The cell stack 10 will be described with reference to FIG.

[0018] The cell stack 10 has a plurality of cell groups 100G. The number of cell groups 100G included in the cell stack 10 is not limited to, but is, for example, 2 to 30. Each cell group 100G includes a plurality of battery cells 100. Each battery cell 100 includes an exterior material 102, a positive electrode lead 112, and a negative electrode lead 114.

[0019] The exterior material 102 accommodates a battery element (not shown) together with an electrolyte (not shown). In one example, the battery element includes a positive electrode, a negative electrode, and a separator (not shown) that are stacked in the second direction Y within the exterior material 102.

[0020] The positive electrode lead 112 is drawn out from one of the front end and rear end of the exterior packaging material 102. The positive electrode lead 112 is electrically connected to a positive electrode inside the exterior packaging material 102. In one example, the positive electrode lead 112 is made of a metal such as aluminum. The length of the portion of the positive electrode lead 112 drawn out from the exterior packaging material 102 is, but is not limited to, for example, 3 cm or more and 9 cm or less. The width of the tip of the portion of the positive electrode lead 112 drawn out from the exterior packaging material 102 is, but is not limited to, for example, 3 cm or more and 9 cm or less. The thickness of the portion of the positive electrode lead 112 drawn out from the exterior packaging material 102 is, but is not limited to, for example, 0.4 mm or more and 0.6 mm or less.

[0021] The negative electrode lead 114 is drawn out from the other of the front end and rear end of the exterior material 102. The negative electrode lead 114 is electrically connected to the negative electrode inside the exterior material 102. In one example, the negative electrode lead 114 is made of a metal different from the metal constituting the positive electrode lead 112, such as copper. The length of the portion of the negative electrode lead 114 drawn out from the exterior material 102 is, but is not limited to, for example, 3 cm or more and 9 cm or less. The width of the tip of the portion of the negative electrode lead 114 drawn out from the exterior material 102 is, but is not limited to, for example, 3 cm or more and 4.5 cm or less. The thickness of the portion of the negative electrode lead 114 drawn out from the exterior material 102 is, but is not limited to, for example, 0.2 mm or more and 0.4 mm or less.

[0022] In the embodiment, the battery cell 100 has a longitudinal direction in the first direction X and a lateral 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 longitudinal direction in the third direction Z and a lateral direction in the first direction X. The width of the battery cell 100 in the third direction Z is, but is not limited to, for example, 8 cm or more and 15 cm or less. The thickness of the battery cell 100 in the second direction Y is, but is not limited to, for example, 0.7 cm or more and 1.6 cm or less.

[0023] In each cell group 100G, the positive electrode leads 112 included in each cell group 100G are connected to each other, and the negative electrode leads 114 included in each cell group 100G are connected to each other. As a result, in each cell group 100G, the battery cells 100 included in each cell group 100G are connected in parallel. In the embodiment, each cell group 100G includes two battery cells 100. However, the number of battery cells 100 included in each cell group 100G may be three or more. Alternatively, the number of battery cells 100 included in each cell group 100G may be only one. In other words, the cell group 100G may be a battery cell 100.

[0024] 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, and 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.

[0025] The plurality of cell groups 100G are connected in series by a plurality of lead portions 110.

[0026] Each lead portion 110 includes one positive electrode lead group 112G of the cell groups 100G adjacent to each other in the second direction Y, and the other negative electrode lead group 114G of the cell groups 100G adjacent to each other in the second direction Y. The positive electrode lead group 112G and the negative electrode lead group 114G are joined to each other by a joining method such as laser welding, ultrasonic bonding, resistance welding, or adhesive. When the positive electrode lead 112 and the negative electrode lead 114 are made of different materials, laser welding is preferred among these joining methods from the viewpoints of high joining reliability and a reduction in the number of parts.

[0027] In the cell stack 10, cell groups 100G in which the positive electrode lead group 112G is located on the front side and the negative electrode lead group 114G is located on the rear side, and cell groups 100G in which the positive electrode lead group 112G is located on the rear side and the negative electrode 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 cell groups 100G adjacent to each other in the second direction Y. As a result, a plurality of lead portions 110 are aligned in the second direction Y at the front of the cell stack 10. A plurality of lead portions 110 are also aligned in the second direction Y at the rear of the cell stack 10. The plurality of lead portions 110 aligned in the second direction Y at the front of the cell stack 10 and the plurality of lead portions 110 aligned in the second direction Y at the rear of the cell stack 10 are aligned alternately in the second direction Y.

[0028] The container 20 will be described with reference to FIGS.

[0029] The housing 20 houses the cell stack 10 and the voltage detection device 30. The housing 20 has 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.

[0030] The first cover member 210 covers the front side of the cell stack 10 and the voltage detection device 30. The second cover member 220 covers the rear side of the cell stack 10. Furthermore, if a voltage detection device (not shown) is provided behind the cell stack 10, the second cover member 220 may cover this voltage detection device. The third cover member 230 covers the right side of the cell stack 10. The fourth cover member 240 covers the left side of the cell stack 10. The fifth cover member 250 covers the lower side of the cell stack 10. The sixth cover member 260 covers the upper side of the cell stack 10. The third cover member 230 and the fourth cover member 240 are parallel to the first direction X.

[0031] The voltage detection device 30 will be described with reference to FIG.

[0032] The voltage detection device 30 includes a holder 300 , a plurality of voltage detection sections 310 , a plurality of voltage detection lines 320 , and a connector 330 .

[0033] The holder 300 is provided in front of the cell stack 10. The holder 300 is attached to the housing 20 by mechanical joining such as snap fitting or screws.

[0034] Each of the plurality of voltage detection units 310 is held by a holder 300. Each of the plurality of voltage detection units 310 is connected to each of the plurality of lead portions 110 at the front of the cell stack 10.

[0035] Each of the plurality of voltage detection wires 320 electrically connects each of the plurality of voltage detection units 310 to the connector 330. In the embodiment, the connector 330 is provided on the upper part of the holder 300. However, the position of the voltage detection unit 310, the routing of the voltage detection wires 320, and the position of the connector 330 are not limited to the example according to the embodiment.

[0036] FIG. 4 is a top view of a portion of the battery module 50 according to the embodiment.

[0037] In Figure 4, the white circle with a black dot indicating the third direction Z indicates that the direction from the back of the paper to the front is the positive direction of the third direction Z, and the direction from the front of the paper to the back is the negative direction of the third direction Z.

[0038] 4, the lead portion 110 on the front side of the cell stack 10 will be described. The matters described in FIG. 4 are also applicable to the lead portion 110 on the rear side of the cell stack 10.

[0039] The positive electrode lead group 112G is drawn out toward the front of the battery cell 100. The positive electrode lead group 112G is also bent at the positive electrode bend portion 112a, so that the tip of the positive electrode lead group 112G is bent toward the negative side of the second direction Y.

[0040] The negative electrode lead group 114G is drawn out toward the front of the cell stack 10. The negative electrode lead group 114G is also bent at the negative electrode bend portion 114a, so that the tip of the negative electrode lead group 114G is bent toward the positive side of the second direction Y.

[0041] At least a portion of the bent tip of the positive electrode lead group 112G and at least a portion of the bent tip of the negative electrode lead group 114G overlap in the first direction X. In the example shown in FIG. 4 , the bent tip of the negative electrode lead group 114G is located further forward in the cell stack 10 than the bent tip of the positive electrode lead group 112G. The length between the positive electrode bend portion 112a and the negative electrode bend portion 114a of the lead portion 110 is, but is not limited to, for example, 0.6 cm or more and 4.0 cm or less. The length in the second direction Y of the overlapping portion of the positive electrode lead group 112G and the negative electrode lead group 114G between the positive electrode bend portion 112a and the negative electrode bend portion 114a is, but is not limited to, for example, 0.7 cm or more and 6.4 cm or less.

[0042] The rear surface of the voltage detection unit 310 is joined to the front surface of the bent tip of the negative electrode lead group 114G by a joining method such as laser welding. The rear surface of the voltage detection unit 310 is preferably made of the same material as the portion of the lead portion 110 that is joined to the voltage detection unit 310. Therefore, for example, in the example shown in FIG. 4, the rear surface of the voltage detection unit 310 is preferably made of the same material as the front surface of the bent tip of the negative electrode lead group 114G.

[0043] For the sake of explanation, a reference plane R is virtually shown by a dashed line in Fig. 4. The reference plane R is a plane perpendicular to the first direction X. In the example shown in Fig. 4, the reference plane R passes between the front surface of the bent tip of the positive electrode lead group 112G and the rear surface of the bent tip of the negative electrode lead group 114G.

[0044] In the embodiment, the average inclination of the front end faces of the plurality of lead portions 110 with respect to the first direction X is 90° or a value relatively close to 90°. Therefore, the accuracy and precision of the bent shape of the lead portions 110 are relatively high. In the example shown in Fig. 4, the front end faces of the lead portions 110 are the front surfaces of the bent tips of the negative electrode lead group 114G.

[0045] In the embodiment, the average inclination of the front end faces of the multiple leads 110 with respect to the first direction X is, for example, 85.0° or more and 95.0° or less. The lower limit of this average is, for example, preferably 86.0°, more preferably 87.5°, and even more preferably 89.0°. The upper limit of this average is, for example, preferably 94.0°, more preferably 92.5°, and even more preferably 91.0°.

[0046] In the embodiment, the maximum value of the inclination of the front end faces of the plurality of leads 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.

[0047] In the embodiment, the minimum value of the inclination of the front end faces of the multiple leads 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.

[0048] The average of the inclinations of the front end faces of the multiple leads 110 with respect to the first direction X is calculated, for example, with reference to all of the leads 110 provided at the front of the cell stack 10. Alternatively, the average may be calculated with reference to a predetermined number of the leads 110 with the smallest inclinations among all of the leads 110 provided at the front of the cell stack 10. This predetermined number is, for example, 50% or more, 60% or more, or 75% of all of the leads 110 provided at the front of the cell stack 10. The same applies to the standard deviation of the inclinations of the front end faces of the multiple leads 110 with respect to the first direction X.

[0049] In the embodiment, the standard deviation of the positional deviation of the front end faces of the plurality of lead portions 110 in the first direction X is zero or relatively small. Therefore, the accuracy and precision of the bent shape of the lead portions 110 are relatively high. In the example shown in Fig. 4, the front end faces of the lead portions 110 are the front surfaces of the bent tips of the negative electrode lead group 114G.

[0050] In the embodiment, the standard deviation of the positional deviation of the front end faces of the leads 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.

[0051] The length in the first direction X from the end face of the lead portion 110 on the front side of the cell stack 10 to the end face of the lead portion 110 on the rear side of the cell stack 10 is, but is not limited to, 35 cm or more and 80 cm or less. The variation in this length among the multiple battery cells 100 is, for example, within ±2 mm, and preferably within ±1 mm.

[0052] The standard deviation of the positional deviation of the front end faces of the multiple leads 110 in the first direction X is calculated, for example, with reference to all of the leads 110 provided at the front of the cell stack 10. Alternatively, the standard deviation may be calculated with reference to a top predetermined number of leads 110 with the smallest deviations described above among all of the leads 110 provided at the front of the cell stack 10. This predetermined number is, for example, 50% or more, 60% or more, or 75% of all of the leads 110 provided at the front of the cell stack 10.

[0053] The standard deviation of the positional deviation of the front end faces of the multiple leads 110 in the first direction X is calculated, for example, by measuring the deviation in the first direction X of the position of the front end faces of the leads 110 relative to a reference plane R. Alternatively, the standard deviation may be calculated by measuring the deviation in the first direction X of the position of the front end faces of the leads 110 relative to a plane parallel to the reference plane R. The reference plane R may be arbitrarily set perpendicular to the first direction X so as to pass through the joint between the front end of the bent tip of the positive electrode lead group 112G and the rear end of the bent tip of the negative electrode lead group 114G. Alternatively, the standard deviation may be calculated by measuring the deviation in length in the first direction X from the end face of the lead 110 on the front side of the cell stack 10 to the end face of the lead 110 on the rear side of the cell stack 10. This length is the length parallel to the X direction. Furthermore, when at least one of the two end faces mentioned above is inclined with respect to the second direction Y when viewed from the third direction Z, the length may be set to 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 cell stack 10 to the end face of the lead portion 110 on the rear side of the cell stack 10.

[0054] 4, the positive electrode lead 112 and the negative electrode lead 114 drawn from the two battery cells 100 of the cell group 100G are schematically depicted as linearly approaching the reference plane R. However, the positive electrode lead 112 and the negative electrode lead 114 may be bent midway.

[0055] 5 to 7 are diagrams illustrating a manufacturing method of the cell stack 10 according to the embodiment. In Fig. 5 to 7, the direction from the back to the front of the paper corresponds to the direction from bottom to top in the vertical direction, and the direction from the front to the back of the paper corresponds to the direction from top to bottom in the vertical direction.

[0056] 5 to 7, of the two cell groups 100G shown in each of Figures 5 to 7, the cell group 100G provided with the positive electrode lead group 112G will be referred to as the cell group 100G on the positive electrode lead group 112G side, as needed. Also, in the description of Figures 5 to 7, of the two cell groups 100G shown in each of Figures 5 to 7, the cell group 100G provided with the negative electrode lead group 114G will be referred to as the cell group 100G on the negative electrode lead group 114G side, as needed.

[0057] The cell stack 10 according to the embodiment is manufactured as follows.

[0058] 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.

[0059] 5 to 7 illustrate the case where the cell groups 100G are connected in series by the lead portions 110. However, the matters explained in FIGS. 5 to 7 are also applicable to the case where a single battery cell 100 is connected in series to another single battery cell 100 by the lead portions 110.

[0060] Next, multiple cell groups 100G are lined up. As shown in Fig. 5, between adjacent cell groups 100G, at least a portion of the positive electrode lead group 112G and at least a portion of the negative electrode lead group 114G are overlapped. Next, between adjacent cell groups 100G, at least a portion of the positive electrode lead group 112G and at least a portion of the negative electrode lead group 114G are joined by a joining method such as laser welding.

[0061] Next, a portion of the lead portion 110 is bent as shown in FIG. 6. In the example shown in FIG. 6, the negative electrode lead group 114G is bent. Next, another portion of the lead portion 110 is bent as shown in FIG. 7. In the example shown in FIG. 7, the positive electrode lead group 112G is bent. In this way, 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. In the example shown in FIGS. 6 and 7, the lead portion 110 is bent using a jig 510, as will be described later with reference to FIGS. 8 and 9.

[0062] The bending of the lead portion 110 in FIGS. 6 and 7 will be described in detail below.

[0063] First, as shown in FIG. 6, the cell group 100G on the negative electrode lead group 114G side is rotated around the negative electrode bend portion 114a. This causes the negative electrode lead group 114G to be bent at a provisional bend angle θ'. The provisional bend angle θ' is set to be larger than the desired bend angle θ at the time shown in FIG. 7 (described later) in consideration of springback of the negative electrode lead group 114G. Therefore, even if the provisional bend angle θ' of the negative electrode lead group 114G is reduced by springback after the step shown in FIG. 6, the desired bend angle θ shown in FIG. 7 can be obtained for the negative electrode lead group 114G. The provisional bend angle θ' is, for example, larger than 90°. The upper limit of the provisional bend angle θ' is not limited to the following, but is, for example, 100° or 95°.

[0064] When the negative electrode lead group 114G is made of copper, the spring back of the negative electrode lead group 114G is likely to be large compared to when the negative electrode lead group 114G is made of a metal other than copper. In the embodiment, even when the spring back of the negative electrode lead group 114G is relatively large, the accuracy and precision of the folded shape of the lead portion 110 can be relatively high.

[0065] When folding back the lead portion 110 between adjacent cell groups 100G, if the lead portion 110 is folded in one step instead of in two steps, it is relatively difficult to take into account the springback of the negative electrode lead group 114G and pre-bend the negative electrode lead group 114G at a bend angle larger than the desired bend angle θ shown in Fig. 7. In the embodiment, compared to when the lead portion 110 is folded in one step, it is easier to take into account the springback of the negative electrode lead group 114G and pre-bend the negative electrode lead group 114G at a bend angle larger than the desired bend angle θ shown in Fig. 7.

[0066] Note that the provisional bending angle θ' shown in FIG. 6 and the desired bending angle θ shown in FIG. 7 are angles formed by the lead portion 110 after the negative electrode lead group 114G has been bent relative to the lead portion 110 shown in FIG. 5 before the negative electrode lead group 114G has been bent.

[0067] Next, as shown in Fig. 7, with the bending angle of the negative electrode lead group 114G set to the desired bending angle θ, the cell group 100G on the positive electrode lead group 112G side is rotated around the positive electrode bending portion 112a. This bends the positive electrode lead group 112G, and the cell group 100G on the positive electrode lead group 112G side is stacked on the cell group 100G on the negative electrode lead group 114G side. In the example shown in Fig. 7, the desired bending angle θ is a right angle.

[0068] The lead portions 110 located between adjacent cell groups 100G among the plurality of cell groups 100G are bent in order according to the method described with reference to Figures 5 to 7. In this way, the plurality of cell groups 100G are stacked in order. In this way, the cell stack 10 is manufactured.

[0069] In the embodiment, as described above, when the lead portion 110 is folded back between adjacent cell groups 100G, the lead portion 110 is bent in two stages. Therefore, compared to when the lead portion 110 is bent in one stage when folding back between adjacent cell groups 100G, it is easier to control the curvature of the lead portion 110 at the positive electrode bend portion 112a and the curvature of the lead portion 110 at the negative electrode bend portion 114a.

[0070] The manufacturing method of the cell stack 10 is not limited to the methods shown in FIGS. 5 to 7. For example, the positive electrode lead group 112G may be bent first, and then the negative electrode lead group 114G may be bent. Specifically, the cell group 100G on the positive electrode lead group 112G side is rotated around the positive electrode bend portion 112a. As a result, the positive electrode lead group 112G is bent at a provisional bend angle larger than the desired bend angle, taking into account the springback of the positive electrode lead group 112G. Next, with the bend angle of the positive electrode lead group 112G set to the desired bend angle, the cell group 100G on the negative electrode lead group 114G side is rotated around the negative electrode bend portion 114a. As a result, the negative electrode lead group 114G is bent, and the cell group 100G on the negative electrode lead group 114G side is stacked on the cell group 100G on the positive electrode lead group 112G side. 5 to 7, the cell group 100G on the negative electrode lead group 114G side is rotated to form the negative electrode bent portion 114a. However, the cell group 100G on the positive electrode lead group 112G side may also be rotated to form the negative electrode bent portion 114a. Furthermore, in the above-described examples, the negative electrode lead group 114G or the positive electrode lead group 112G is bent at a provisional bend angle. However, the negative electrode lead group 114G or the positive electrode lead group 112G may be bent at a desired bend angle without bending the negative electrode lead group 114G or the positive electrode lead group 112G at a provisional bend angle.

[0071] 8 and 9 are diagrams for explaining the details of the method for bending the lead portion 110. FIG.

[0072] 8 and 9, the lead portion 110 is bent using a jig 510. The jig 510 has a center clamp 512, a positive electrode clamp 514, and a negative electrode clamp 516.

[0073] 8, the central clamp 512 holds the overlapping portion of the tip of the positive electrode lead group 112G and the tip of the negative electrode lead group 114G. That is, the jig 510 is a holding portion that holds at least a portion of the lead portion 110.

[0074] As shown in FIG. 8 , the positive electrode clamp 514 grips the positive electrode lead 112 of the cell group 100G on the positive electrode lead group 112G side. The positive electrode clamp 514 is generally V-shaped. Specifically, the surface of the positive electrode clamp 514 on the exterior material 102 side is shaped to cover the tip of the exterior material 102 of the cell group 100G on the positive electrode lead group 112G side via a gap. This makes it difficult for this surface of the positive electrode clamp 514 to come into contact with the exterior material 102. This allows the positive electrode clamp 514 to reliably grip the portion of the positive electrode lead 112 near the exterior material 102. For example, the positive electrode clamp 514 grips the positive electrode lead 112 at a position 1.5 mm or more and less than 5.0 mm away from the end of the exterior material 102, preferably 2.0 mm or more and 3.5 mm or less. In this example, damage to the positive lead 112 and the seal portion of the exterior material 102 can be suppressed compared to when the position where the positive clamp 514 grips the positive lead 112 is closer to the end of the exterior material 102 than the above-mentioned range. Furthermore, in the above-mentioned example, the accuracy of bending the positive lead 112 can be improved compared to when the position where the positive clamp 514 grips the positive lead 112 is farther from the end of the exterior material 102 than the above-mentioned range. The positive clamp 514 is directly or indirectly attached to a cell fixing portion that fixes the cell group 100G (not shown). Therefore, the positive clamp 514 does not rotate relative to the exterior material 102 of the battery cell 100. As a result, even when the positive clamp 514 is rotated relative to the central clamp 512, the cell group 100G rotates integrally with the positive lead group 112G near the exterior material 102. Therefore, bending of the positive lead 112 located inside the exterior material 102 can be prevented. Furthermore, the inclination of the end face of the lead portion 110 with respect to the reference plane R after the lead portion 110 is bent can be reduced. Furthermore, the force applied to the portion of the positive electrode lead 112 that is sandwiched between the exterior material 102 can be suppressed. This prevents the exterior material 102 from being scratched, and also prevents breakage of the connection portion between the battery element (not shown) and the positive electrode lead 112.

[0075] The negative electrode clamp 516 has a structure similar to that of the positive electrode clamp 514. As shown in FIG. 8 , the negative electrode clamp 516 grips 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 grips the negative electrode lead 114 at a position that is 1.5 mm or more and less than 5.0 mm, preferably 2.0 mm or more and 3.5 mm or less, from the end of the outer casing 102. In this example, damage to the negative electrode lead 114 and the seal portion of the outer casing 102 can be suppressed compared to when the position at which the negative electrode clamp 516 grips the negative electrode lead 114 is closer to the end of the outer casing 102 than the above-mentioned range. Furthermore, in the above-mentioned example, the bending accuracy of the negative electrode lead 114 can be improved compared to when the position at which the negative electrode clamp 516 grips the negative electrode lead 114 is farther from the end of the outer casing 102 than the above-mentioned range. The negative electrode clamp 516 is also attached directly or indirectly to a cell fixing part that fixes the cell group 100G (not shown). Therefore, the negative electrode clamp 516 is prevented from rotating relative to the exterior packaging material 102 of the battery cell 100.

[0076] Next, as shown in Fig. 9, negative electrode clamp 516 is rotated relative to central clamp 512. This causes negative electrode lead group 114G to bend around negative electrode bent portion 114a. In this case, as described using Fig. 6, taking into account springback of negative electrode lead group 114G, negative electrode lead group 114G is bent at a provisional bending angle θ' that is greater than 90°.

[0077] Next, the positive electrode clamp 514 is rotated relative to the central clamp 512. This causes the positive electrode lead group 112G to bend around the positive electrode bent portion 112a.

[0078] In bending the lead portion 110 shown in FIGS. 8 and 9, it is preferable that the axis of rotation for bending the negative electrode lead group 114G and the axis of rotation for bending the positive electrode lead group 112G are different.

[0079] 8 and 9, the cell group 100G on the negative electrode lead group 114G side is rotated to form the negative electrode bent portion 114a. However, the cell group 100G on the positive electrode lead group 112G side may be rotated to form the negative electrode bent portion 114a. [Example]

[0080] In the following examples, the cell stack 10 according to the embodiment will be specifically exemplified. Note that the cell stack 10 according to the embodiment is not limited to the cell stack 10 described in the examples.

[0081] Example 1 The cell stack 10 according to Example 1 was manufactured as follows.

[0082] Twenty cell groups 100G were manufactured. Each cell group 100G included two battery cells 100. Two positive electrode leads 112 were drawn from one end of the exterior packaging 102 of each cell group 100G. Two negative electrode leads 114 were drawn from the other end of the exterior packaging 102 of each cell group 100G. Each positive electrode lead 112 was an aluminum lead. The length of the portion of the positive electrode lead 112 drawn from the exterior packaging 102, the width and thickness of its tip were 3 cm, 4.5 cm and 0.4 mm, respectively. Each negative electrode lead 114 was a copper lead. The length of the portion of the negative electrode lead 114 drawn from the exterior packaging 102, the width and thickness of its tip were 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 was 55 cm. The width of each battery cell 100 was 59 cm. The thickness of each battery cell 100 was set to 0.8 cm.

[0083] Next, these cell groups 100G were lined up. Furthermore, as shown in FIG. 5, between adjacent cell groups 100G, a portion of the positive electrode lead group 112G and a portion of the negative electrode lead group 114G were overlapped. Next, the portion of the positive electrode lead group 112G and the portion of the negative electrode lead group 114G were joined by laser welding. The length of the overlapping portion of the positive electrode lead group 112G and the negative electrode lead group 114G in the direction from one side of the adjacent cell groups 100G to the other side was 1 cm.

[0084] Next, as shown in Fig. 6, the cell group 100G on the side of the negative electrode lead group 114G was rotated around the negative electrode bent portion 114a. As a result, the negative electrode lead group 114G was bent at 90°. The jig 510 described with reference to Figs. 8 and 9 was used to bend the negative electrode lead group 114G. When bending the negative electrode lead group 114G, the negative electrode lead group 114G was gripped by a negative electrode clamp 516 at a position 2.0 mm to 3.5 mm away from the end of the exterior packaging material 102.

[0085] Next, as shown in FIG. 7, with the bending angle θ of the negative electrode lead group 114G set to a right angle, the cell group 100G on the positive electrode lead group 112G side was rotated around the positive electrode bend portion 112a. This bent the positive electrode lead group 112G, and the cell group 100G on the positive electrode lead group 112G side was stacked on the cell group 100G on the negative electrode lead group 114G side. The jig 510 described with reference to FIGS. 8 and 9 was used to bend the positive electrode lead group 112G. When bending the positive electrode lead group 112G, the positive electrode lead group 112G was held by a positive electrode clamp 514 at a position 2.0 mm to 3.5 mm away from the end of the exterior material 102. The length between the positive electrode bend portion 112a and the negative electrode bend portion 114a of the lead portion 110 was 1 cm.

[0086] The lead portions 110 located between adjacent cell groups 100G among the plurality of cell groups 100G were bent in order according to the method described above. In this way, the plurality of cell groups 100G were stacked in order. The length from the position of the end face of the lead portion 110 on the front side of the cell stack 10 to the position of the end face of the lead portion 110 on the rear side of the cell stack 10 was set to 550 mm. In this way, the cell stack 10 according to Example 1 was manufactured.

[0087] Example 2 The cell stack according to Example 2 was produced in the same manner as the cell stack according to Example 1, except for the following points.

[0088] In Example 2, as shown in Fig. 6, the cell group 100G on the side of the negative electrode lead group 114G was rotated around the negative electrode bending portion 114a. As a result, the negative electrode lead group 114G was bent at a provisional bending angle θ' (95°) greater than 90°. The jig 510 described with reference to Figs. 8 and 9 was used to bend the negative electrode lead group 114G. When bending the negative electrode lead group 114G, the negative electrode clamp 516 gripped a position 2.0 mm to 3.5 mm away from the end of the exterior packaging material 102 of the negative electrode lead group 114G.

[0089] Next, as shown in Fig. 7, with the bending angle θ of the negative electrode lead group 114G set to a right angle, the cell group 100G on the positive electrode lead group 112G side was rotated around the positive electrode bending portion 112a. In this way, the positive electrode lead group 112G was bent, and the cell group 100G on the positive electrode lead group 112G side was stacked on the cell group 100G on the negative electrode lead group 114G side. The jig 510 described with reference to Figs. 8 and 9 was used to bend the positive electrode lead group 112G. When bending the positive electrode lead group 112G, a position 2.0 mm to 3.5 mm away from the end of the exterior material 102 of the positive electrode lead group 112G was gripped by a positive electrode clamp 514.

[0090] The lead portions 110 located between adjacent cell groups 100G among the plurality of cell groups 100G were bent in order according to the method described above. In this way, the plurality of cell groups 100G were stacked in order. In this way, the cell stack 10 according to Example 2 was manufactured.

[0091] Example 3 Example 3 was the same as Example 2, except that the length from the end face of the lead portion 110 on the front side of the cell stack 10 to the end face of the lead portion 110 on the rear side of the cell stack 10 was 350 mm.

[0092] Example 4 Example 4 was the same as Example 1, except that the length from the end face of the lead portion 110 on the front side of the cell stack 10 to the end face of the lead portion 110 on the rear side of the cell stack 10 was 350 mm, and 10 cell groups 100G were manufactured, each containing 20 battery cells 100.

[0093] (Comparative Example) The cell stack 10 according to the comparative example was manufactured in the same manner as the cell stack 10 according to the example 1, except for the following points.

[0094] 5, in the comparative example, after joining a portion of the positive electrode lead group 112G and a portion of the negative electrode lead group 114G, the cell group 100G on the positive electrode lead group 112G side was rotated with respect to the cell group 100G on the negative electrode lead group 114G side by a single bending process, and the cell group 100G on the positive electrode lead group 112G side was stacked on the cell group 100G on the negative electrode lead group 114G side. In other words, in the comparative example, the bending step of rotating the cell group 100G on the positive electrode lead group 112G side around the negative electrode bending portion 114a and the bending step of rotating the cell group 100G on the positive electrode bending portion 112a side around the positive electrode bending portion 112a were not performed.

[0095] Table 1 shows the average inclination of the end faces of the multiple lead portions 110 with respect to the direction perpendicular to the stacking direction of the multiple cell groups 100G for Examples 1 to 4 and the comparative example. In Table 1, the number in the "Average (°)" column indicates the average of the inclination (unit: °). The number in the "Maximum (°)" column indicates the maximum value of the inclination (unit: °). The number in the "Minimum (°)" column indicates the minimum value of the inclination (unit: °). [Table 1]

[0096] In Examples 1 to 4 and the comparative example, the average of the above-mentioned tilt was calculated with reference to all of the lead portions 110 provided at the front of the cell stack 10. In calculating the average, the tilt with respect to the length direction of the battery cells 100 was measured. The length direction of the battery cells 100 is the first direction X in the example shown in FIG. 4. In Examples 1 to 4, the average of the above-mentioned tilt was 85.0° or more and 95.0° or less. In Examples 1 to 4, the maximum value of the above-mentioned tilt was 97.5° or less. In Examples 1 to 4, the minimum value of the above-mentioned tilt was 87.5° or more.

[0097] Table 2 shows the standard deviation of the positional deviation of the end faces of the multiple leads 110 in the direction perpendicular to the stacking direction of the multiple cell groups 100G for Examples 1 to 4 and the comparative example. In Table 2, the numbers in the "Standard deviation (mm)" column indicate the standard deviation (unit: mm). [Table 2]

[0098] In Examples 1 to 4 and the Comparative Example, the above-mentioned standard deviation was calculated with reference to all of the lead portions 110 provided at the front of the cell stack 10. In calculating the standard deviation, the above-mentioned deviation in the length direction of the battery cells 100 was measured. The length direction of the battery cells 100 is the first direction X in the example shown in FIG. 4. In Examples 1 to 4, the above-mentioned standard deviation was greater than or equal to 0 mm and less than or equal to 2.50 mm.

[0099] A comparison between Examples 1 to 4 and the comparative example reveals that when the lead portion 110 is bent in two stages when folding back the lead portion 110 between adjacent cell groups 100G, the accuracy and precision of the folded shape of the lead portion 110 can be improved compared to when the lead portion 110 is bent in one step when folding back the lead portion 110 between adjacent cell groups 100G.

[0100] Although the embodiments and examples of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted. [Explanation of symbols]

[0101] 10 Cell stack 20 Containment Unit 30 Voltage detection device 50 Battery Module 100 battery cells 100G cell group 102 Exterior materials 110 Lead section 112 Positive lead 112G Positive lead group 112a Positive electrode bending part 114 Negative lead 114G negative electrode lead group 114a Negative electrode bending part 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 Holder 310 Voltage detection unit 320 Voltage detection wire 330 Connector 510 Jig 512 Center Clamp 514 Positive Clamp 516 Negative clamp R reference plane X 1st direction Y Second direction Z 3rd direction

Claims

1. a step of connecting at least one positive electrode lead of at least one battery cell and at least one negative electrode lead of at least one other battery cell to form a lead portion, and bending a portion of the lead portion; bending another portion of the lead portion after bending the portion of the lead portion; A method for manufacturing a battery module comprising:

2. 2. The method for manufacturing a battery module according to claim 1, wherein the step of bending the portion of the lead portion includes a step of bending the portion of the lead portion at a bending angle that is larger than a bending angle of the portion of the lead portion after the other portion of the lead portion is bent.

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