Battery module

Abstract

To improve the accuracy and precision of the folded shape of the lead section. [Solution] The battery module 50 comprises 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, wherein the average inclination of the end faces of the plurality of lead portions 110 with respect to a direction perpendicular to the predetermined direction is 85.0° or more and 95.0° 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 includes a plurality of stacked battery cells. For example, as described in Patent Document 1, in some battery modules, a plurality of battery cells connected in parallel and a plurality of other battery cells connected in parallel may be connected in series by a lead portion. In this battery module, the lead portion is folded between the plurality of battery cells and the plurality of other battery cells.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems 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 folded by a single bending process to fold back the lead portion between the at least one battery cell and the at least one other battery cell. However, when the lead portion is folded by a single bending process, the accuracy and precision of the folded shape of the lead portion may be relatively low.

[0005] An example of the object of the present invention is to increase the accuracy and precision of the folded shape of the lead portion. Other objects of the present invention will become apparent from the description herein.

Means for Solving the Problems

[0006] One aspect of the present invention is as follows: [1] Multiple battery cells stacked in a predetermined direction, Each of the multiple lead portions is folded back between at least one battery cell and at least one other battery cell, Equipped with, A battery module in which the average of the inclinations of the end faces of the plurality of lead portions with respect to a direction perpendicular to the predetermined direction is 85.0° or more and 95.0° or less. [2] Multiple battery cells stacked in a predetermined direction, Each of the multiple lead portions is folded back 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 misalignment of the end faces of the plurality of lead portions in a direction perpendicular to the predetermined direction is 0 or more and 2.50 mm or less. [3] A step of bending a portion of the lead that connects at least one battery cell to at least one other battery cell, The steps include bending one portion of the lead portion and then bending another portion of the lead portion, A method for manufacturing a battery module, comprising: [4] The method for manufacturing a battery module according to [3], wherein the step of bending the portion of the lead portion is to bend the portion of the lead portion at a bending angle greater than the bending angle of the portion of the lead portion after bending the other portion of the lead portion. [Effects of the Invention]

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

[0008] [Figure 1] This is a perspective view of the battery module according to the embodiment, seen from the front. [Figure 2] It is a view showing the removal of the container from FIG. 1. [Figure 3] It is a perspective view of the cell stack according to the embodiment as seen from the front. [Figure 4] It is a top view of a part of the battery module according to the embodiment. [Figure 5] It is a diagram for explaining a method of manufacturing the cell stack according to the embodiment. [Figure 6] It is a diagram for explaining a method of manufacturing the cell stack according to the embodiment. [Figure 7] It is a diagram for explaining a method of manufacturing the cell stack according to the embodiment. [Figure 8] It is a diagram for explaining the details of a method of bending the lead portion. [Figure 9] It is a diagram for explaining the details of a method of bending the lead portion.

Mode for Carrying Out the Invention

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

[0010] In this specification, ordinal numbers such as "first", "second", "third", etc. are given simply to distinguish configurations with the same name, unless otherwise specified, and do not mean specific features of the configuration (for example, order or importance).

[0011] FIG. 1 is a perspective view of the battery module 50 according to the embodiment as seen from the front. FIG. 2 is a view showing the removal of the container 20 from FIG. 1. FIG. 3 is a perspective view of the cell stack 10 according to the embodiment as seen from the front.

[0012] In FIGS. 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 to the tip of the arrow is the positive direction of the direction indicated by the arrow, and the direction from the tip to the base end of the arrow 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-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 both 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 right to 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 left to 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 the bottom to the top of the battery module 50. The negative direction of the third direction Z is the direction from the top to the bottom of the battery module 50.

[0013] The relationships among the first direction X, the second direction Y, the third direction Z, the vertical direction, and the horizontal direction are not limited to the above-described example. For example, the cell stack 10 may be arranged such that the first direction X or the second direction Y is parallel to the vertical direction.

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

[0015] In this embodiment, the battery module 50 is mounted on a moving body such as an automobile. However, the use of the battery module 50 is not limited to this example.

[0016] The battery module 50 comprises 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) located behind the cell stack 10. The voltage detection device located behind the cell stack 10 has a configuration similar to, for example, the voltage detection device 30 shown in Figure 2.

[0017] The cell stack 10 will be explained using Figure 3.

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

[0019] The outer casing 102 houses a battery element (not shown) along with an electrolyte (not shown). In one example, the battery element includes a positive electrode, a negative electrode, and a separator (not shown) stacked in a second direction Y within the outer casing 102.

[0020] The positive electrode lead 112 is drawn out from either the front or rear end of the housing material 102. The positive electrode lead 112 is electrically connected to the positive electrode inside the housing 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 housing material 102 is not limited to the following, but is for example between 3 cm and 9 cm. The width of the tip of the portion of the positive electrode lead 112 drawn out from the housing material 102 is not limited to the following, but is for example between 3 cm and 9 cm. The thickness of the portion of the positive electrode lead 112 drawn out from the housing material 102 is not limited to the following, but is for example between 0.4 mm and 0.6 mm.

[0021] The negative electrode lead 114 is drawn out from the front end and the other end of the rear end of the housing material 102. The negative electrode lead 114 is electrically connected to the negative electrode inside the housing material 102. In one example, the negative electrode lead 114 is made of a different metal from the metal that makes up the positive electrode lead 112, for example, copper. The length of the portion of the negative electrode lead 114 drawn out from the housing material 102 is not limited to the following, but 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 housing material 102 is not limited to the following, but 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 housing material 102 is not limited to the following, but for example, 0.2 mm or more and 0.4 mm or less.

[0022] In this embodiment, the battery cell 100 has a longitudinal direction in the first direction X and a short 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 short direction in the first direction X. The width of the battery cell 100 in the third direction Z is not limited to the following, but for example, it is 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 the following, but for example, it is 0.7 cm or more and 1.6 cm or less.

[0023] In each cell group 100G, multiple positive electrode leads 112 included in each cell group 100G are connected to each other, and multiple negative electrode leads 114 included in each cell group 100G are connected to each other. As a result, in each cell group 100G, multiple battery cells 100 included in each cell group 100G are connected in parallel. In this 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 single battery cell 100.

[0024] Hereafter, if necessary, the multiple positive electrode leads 112 included in each cell group 100G will be referred to as the positive electrode lead group 112G. Also, if necessary, the multiple negative electrode leads 114 included in each cell group 100G will be referred to as the negative electrode lead group 114G.

[0025] Multiple cell groups 100G are connected in series by multiple lead sections 110.

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

[0027] In the cell stack 10, cell groups 100G in which the positive electrode lead group 112G is located at the front and the negative electrode lead group 114G is located at the rear, and cell groups 100G in which the positive electrode lead group 112G is located at the rear and the negative electrode lead group 114G is located at the front, are stacked alternately in the second direction Y. Each lead portion 110 is folded back between adjacent cell groups 100G in the second direction Y. As a result, at the front of the cell stack 10, multiple lead portions 110 are aligned in the second direction Y. Similarly, at the rear of the cell stack 10, multiple lead portions 110 are also aligned in the second direction Y. The multiple lead portions 110 aligned in the second direction Y at the front of the cell stack 10 and the multiple lead portions 110 aligned in the second direction Y at the rear of the cell stack 10 are arranged alternately in the second direction Y.

[0028] The containment 20 will be explained using Figures 1 and 2.

[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. If a voltage detection device (not shown) is provided at the rear of the cell stack 10, the second cover member 220 may also 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 bottom side of the cell stack 10. The sixth cover member 260 covers the top 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 explained using Figure 2.

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

[0033] The retainer 300 is located in front of the cell stack 10. The retainer 300 is attached to the housing 20 by mechanical fastening such as snap-fits or screws.

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

[0035] Each of the multiple voltage detection lines 320 electrically connects each of the multiple voltage detection units 310 to the connector 330. In this embodiment, the connector 330 is located on the upper part of the holder 300. However, the location of the voltage detection units 310, the routing of the voltage detection lines 320, and the location of the connector 330 are not limited to the examples of this embodiment.

[0036] Figure 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 shows that the direction from the back of the paper towards the front is the positive direction of the third direction Z, and the direction from the front of the paper towards the back is the negative direction of the third direction Z.

[0038] Figure 4 illustrates the front lead portion 110 of the cell laminate 10. The matters described in Figure 4 are also applicable to the rear lead portion 110 of the cell laminate 10.

[0039] The positive electrode lead group 112G is drawn out toward the front of the battery cell 100. Furthermore, the positive electrode lead group 112G is bent at the positive electrode bending portion 112a. As a result, the tip of the positive electrode lead group 112G is bent toward the negative direction of the second direction Y.

[0040] The negative electrode lead group 114G is drawn out toward the front of the cell laminate 10. Furthermore, the negative electrode lead group 114G is bent at the negative electrode bending portion 114a. As a result, the tip of the negative electrode lead group 114G is bent toward the positive direction of the second direction Y.

[0041] At least a portion of the bent tip of the positive lead group 112G and at least a portion of the bent tip of the negative lead group 114G overlap in the first direction X. In the example shown in Figure 4, the bent tip of the negative lead group 114G is located further forward on the cell laminate 10 than the bent tip 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 the following, but is 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 lead group 112G and the negative lead group 114G between the positive bent portion 112a and the negative bent portion 114a is not limited to the following, but is 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. Preferably, the rear surface of the voltage detection unit 310 is made of the same material as the portion of the lead 110 that is joined to the voltage detection unit 310. For example, in the example shown in Figure 4, it is preferable that the rear surface of the voltage detection unit 310 is made of the same material as the front surface of the bent tip of the negative electrode lead group 114G.

[0043] In Figure 4, a reference plane R is hypothetically shown by a dashed line for illustrative purposes. The reference plane R is a plane perpendicular to the first direction X. In the example shown in Figure 4, the reference plane R passes between the front surface of the bent tip of the positive lead group 112G and the rear surface of the bent tip of the negative lead group 114G.

[0044] In this embodiment, the average of the inclinations of the front end faces of the multiple lead portions 110 with respect to the first direction X is 90° or a value that is relatively close to 90°. Therefore, the accuracy and precision of the bent shape of the lead portion 110 are relatively high. In the example shown in Figure 4, the front end face of the lead portion 110 is the front surface of the bent tip of the negative electrode lead group 114G.

[0045] In the embodiment, the average of the inclination of the front end faces of the multiple 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 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 inclination of the front end faces of the multiple 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.

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

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

[0049] In this embodiment, the standard deviation of the misalignment of the front end faces of the multiple 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 Figure 4, the front end face of the lead portion 110 is the front surface of the bent tip of the negative electrode lead group 114G.

[0050] In this embodiment, the standard deviation of the misalignment of the front end faces of the multiple 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.

[0051] The length in the first direction X from the end face of the front lead portion 110 of the cell stack 10 to the end face of the rear lead portion 110 of the cell stack 10 is not limited to the following, but is for example 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, preferably within ±1 mm.

[0052] The standard deviation of the positional misalignment of the front end faces of the multiple lead portions 110 in the first direction X is calculated, for example, by referring to all the lead portions 110 provided in front of the cell stack 10. Alternatively, the standard deviation may be calculated by referring to a predetermined number of lead portions 110 with the smallest misalignment among all the lead portions 110 provided in front of the cell stack 10. This predetermined number is, for example, 50% or more, 60% or more, or 75% of all the lead portions 110 provided in front of the cell stack 10.

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

[0054] In Figure 4, the positive electrode lead 112 and negative electrode lead 114 drawn from the two battery cells 100 of cell group 100G are schematically depicted as approaching the reference plane R in a straight line. However, the positive electrode lead 112 and the negative electrode lead 114 may be bent along the way.

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

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

[0057] The cell laminate 10 according to this embodiment is manufactured as follows.

[0058] First, multiple cell groups 100G are formed. Each cell group 100G has multiple battery cells 100 stacked on top of each other. In this embodiment, each cell group 100G contains two stacked battery cells 100. However, the number of battery cells 100 included in each cell group 100G is not limited to two, but may be three or more.

[0059] Figures 5 to 7 illustrate the connection of the cell group 100G in series using the lead portion 110. However, the matters described in Figures 5 to 7 are also applicable when a single battery cell 100 is connected in series with another single battery cell 100 using the lead portion 110.

[0060] Next, multiple cell groups 100G are arranged side by side. As shown in Figure 5, in 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 superimposed. Then, 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.

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

[0062] Details of the bending of the lead portion 110 in Figures 6 and 7 will be explained below.

[0063] First, as shown in Figure 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 bend at a temporary bending angle θ'. The temporary bending angle θ' is larger than the desired bending angle θ at the point shown in Figure 7, which will be described later, taking into account the springback of the negative electrode lead group 114G. Therefore, even if the temporary bending angle θ' of the negative electrode lead group 114G decreases due to springback after the process shown in Figure 6, the desired bending angle θ shown in Figure 7 can be obtained for the negative electrode lead group 114G. The temporary bending angle θ' is, for example, larger than 90°. The upper limit of the temporary bending 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 springback of the negative electrode lead group 114G tends to be greater compared to when the negative electrode lead group 114G is made of a metal other than copper. In this embodiment, even when the springback 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 made relatively high.

[0065] When folding 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 pre-fold the negative electrode lead group 114G at a bending angle larger than the desired bending angle θ shown in Figure 7, taking into account the springback of the negative electrode lead group 114G. In this embodiment, compared to the case where the lead portion 110 is folded in one step, it is easier to pre-fold the negative electrode lead group 114G at a bending angle larger than the desired bending angle θ shown in Figure 7, taking into account the springback of the negative electrode lead group 114G.

[0066] The provisional bending angle θ' shown in Figure 6 and the desired bending angle θ shown in Figure 7 are the angles that the lead portion 110 after the negative electrode lead group 114G has been bent are made with respect to the lead portion 110 shown in Figure 5 before the negative electrode lead group 114G is bent.

[0067] Next, as shown in Figure 7, with the negative electrode lead group 114G bent at the desired bending angle θ, the cell group 100G on the positive electrode lead group 112G side is rotated around the positive electrode bend 112a. This bends the positive electrode lead group 112G, stacking the cell group 100G on the positive electrode lead group 112G side onto the cell group 100G on the negative electrode lead group 114G side. In the example shown in Figure 7, the desired bending angle θ is a right angle.

[0068] The lead portions 110 located between adjacent cell groups 100G are sequentially bent according to the method described with reference to Figures 5 to 7. This stacks the cell groups 100G sequentially. In this way, the cell laminate 10 is manufactured.

[0069] In this 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 the case where the lead portion 110 is bent in one step when folding it back between adjacent cell groups 100G, it is easier to control the curvature of the lead portion 110 at the positive electrode bent portion 112a and the curvature of the lead portion 110 at the negative electrode bent portion 114a.

[0070] The method for manufacturing the cell laminate 10 is not limited to the method shown in Figures 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. This bends the positive electrode lead group 112G to a temporary bend angle larger than the desired bending angle, taking into account the springback of the positive electrode lead group 112G. Next, with the bending angle of the positive electrode lead group 112G set to the desired bending angle, the cell group 100G on the negative electrode lead group 114G side is rotated around the negative electrode bend portion 114a. This bends the negative electrode lead group 114G, and the cell group 100G on the negative electrode lead group 114G side is laminated onto the cell group 100G on the positive electrode lead group 112G side. Furthermore, in the examples shown in Figures 5 to 7, the cell group 100G on the negative electrode lead group 114G side is rotated to form the negative electrode bend 114a. However, the cell group 100G on the positive electrode lead group 112G side may also be rotated to form the negative electrode bend 114a. Also, in the examples described above, the negative electrode lead group 114G or the positive electrode lead group 112G is bent at a provisional bending angle. However, the negative electrode lead group 114G or the positive electrode lead group 112G may be bent to a desired bending angle without bending them at a provisional bending angle.

[0071] Figures 8 and 9 are diagrams illustrating in detail the method for bending the lead portion 110.

[0072] In the examples shown in Figures 8 and 9, the lead portion 110 is bent using a jig 510. The jig 510 has a central clamp 512, a positive electrode clamp 514, and a negative electrode clamp 516.

[0073] As shown in Figure 8, the central clamp 512 grips the overlapping portion of the tips of the positive lead group 112G and the negative lead group 114G. In other words, the jig 510 is a gripping portion that grips at least a part of the lead portion 110.

[0074] As shown in Figure 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 has a roughly V-shape. Specifically, the surface of the positive electrode clamp 514 on the outer casing material 102 side is shaped to cover the tip of the outer casing material 102 of the cell group 100G on the positive electrode lead group 112G side through a gap. Therefore, this surface of the positive electrode clamp 514 is less likely to come into contact with the outer casing material 102. This ensures that the portion of the positive electrode lead 112 near the outer casing material 102 is securely gripped by the positive electrode clamp 514. For example, the positive electrode clamp 514 grips the positive electrode lead 112 at a position 1.5 mm to less than 5.0 mm away from the end of the outer casing material 102, preferably at a position 2.0 mm to 3.5 mm away. In this example, compared to the case where the position where the positive electrode clamp 514 grips the positive electrode lead 112 is closer to the end of the outer casing material 102 than the range described above, damage to the seal portion of the positive electrode lead 112 and the outer casing material 102 can be suppressed. Also, in the above example, compared to the case where the position where the positive electrode clamp 514 grips the positive electrode lead 112 is further from the end of the outer casing material 102 than the range described above, the bending accuracy of the positive electrode lead 112 can be improved. The positive electrode clamp 514 is directly or indirectly attached to the cell fixing part that fixes the cell group 100G (not shown). Therefore, the positive electrode clamp 514 does not rotate relative to the outer casing material 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 casing material 102. Therefore, bending of the positive electrode lead 112 located inside the outer casing 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 bending the lead portion 110 can be reduced. In addition, the force applied to the portion of the positive electrode lead 112 sandwiched by the outer casing material 102 can be suppressed. This prevents damage to the outer casing material 102 and 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 the same structure as the positive electrode clamp 514. As shown in Figure 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 1.5 mm or more but less than 5.0 mm away from the end of the outer material 102, preferably 2.0 mm or more but 3.5 mm away. In this example, compared to the case where the position where the negative electrode clamp 516 grips the negative electrode lead 114 is closer to the end of the outer material 102 than the range described above, damage to the seal portion of the negative electrode lead 114 and outer material 102 can be suppressed. Also, in the above example, compared to the case where the position where the negative electrode clamp 516 grips the negative electrode lead 114 is further away from the end of the outer material 102 than the range described above, the bending accuracy of the negative electrode lead 114 can be improved. The negative electrode clamp 516 is also directly or indirectly attached to the cell fixing part that secures the cell group 100G (not shown). Therefore, the negative electrode clamp 516 is prevented from rotating relative to the outer casing material 102 of the battery cell 100.

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

[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 bend portion 112a.

[0078] In the bending of the lead portion 110 shown in Figures 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] In the examples shown in Figures 8 and 9, the cell group 100G on the negative electrode lead group 114G side is rotated to form the negative electrode bend 114a. However, the cell group 100G on the positive electrode lead group 112G side may also be rotated to form the negative electrode bend 114a. [Examples]

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

[0081] (Example 1) The cell laminate 10 according to Example 1 was manufactured as follows.

[0082] Twenty cell groups 100G were manufactured. Each cell group 100G contains two battery cells 100. Two positive electrode leads 112 are drawn out from one end of the casing material 102 of each cell group 100G. Two negative electrode leads 114 are drawn out from the other end of the casing material 102 of each cell group 100G. Each positive electrode lead 112 was made of aluminum. The length, tip width, and thickness of the portion of the positive electrode lead 112 drawn out from the casing material 102 were 3 cm, 4.5 cm, and 0.4 mm, respectively. Each negative electrode lead 114 was made of copper. The length, tip width, and thickness of the portion of the negative electrode lead 114 drawn out from the casing material 102 were 3 cm, 4.5 cm, and 0.2 mm, respectively. The length of each battery cell 100 excluding the positive electrode leads 112 and negative electrode leads 114 was 55 cm. The width of each battery cell 100 was 59 cm. Each battery cell (100) had a thickness of 0.8 cm.

[0083] Next, these cell groups 100G were arranged side by side. As shown in Figure 5, a portion of the positive lead group 112G and a portion of the negative lead group 114G were overlapped between adjacent cell groups 100G. Then, the portions of the positive lead group 112G and the negative lead group 114G were 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 adjacent cell group 100G to the other was set to 1 cm.

[0084] Next, as shown in Figure 6, the cell group 100G on the negative electrode lead group 114G side was rotated around the negative electrode bend portion 114a. This bent the negative electrode lead group 114G at a 90° angle. The jig 510, which was described using Figures 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 the negative electrode lead group 114G at a position 2.0 mm to 3.5 mm away from the end of the outer material 102.

[0085] Next, as shown in Figure 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 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, which was explained using Figures 8 and 9, was used to bend the positive electrode lead group 112G. When bending the positive electrode lead group 112G, the positive electrode clamp 514 gripped the positive electrode lead group 112G at a position 2.0 mm to 3.5 mm away from the end of the outer material 102. The length between the positive electrode bend 112a and the negative electrode bend 114a of the lead portion 110 was set to 1 cm.

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

[0087] (Example 2) The cell laminate according to Example 2 was manufactured in the same manner as the cell laminate according to Example 1, except for the following points.

[0088] In Example 2, as shown in Figure 6, the cell group 100G on the negative electrode lead group 114G side was rotated around the negative electrode bend portion 114a. This resulted in bending the negative electrode lead group 114G to a temporary bending angle θ' (95°) greater than 90°. The jig 510, as explained with reference to Figures 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 the negative electrode lead group 114G at a position 2.0 mm to 3.5 mm away from the end of the outer material 102.

[0089] Next, as shown in Figure 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 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, which was explained using Figures 8 and 9, was used to bend the positive electrode lead group 112G. When bending the positive electrode lead group 112G, the positive electrode clamp 514 gripped the positive electrode lead group 112G at a position 2.0 mm to 3.5 mm away from the end of the outer material 102.

[0090] The lead portions 110 located between adjacent cell groups 100G in a plurality of cell groups 100G are bent sequentially according to the method described above. In this way, the plurality of cell groups 100G are stacked sequentially. In this manner, the cell laminate 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 front lead portion 110 of the cell laminate 10 to the end face of the rear lead portion 110 of the cell laminate 10 was set to 350 mm.

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

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

[0094] In the comparative example, as shown in Figure 5, after joining a portion of the positive lead group 112G and a portion of the negative lead group 114G, the cell group 100G on the positive lead group 112G side was rotated relative to the cell group 100G on the negative lead group 114G side by a single bending process, thereby stacking the cell group 100G on the positive lead group 112G side onto 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 electrode bending portion 114a, and the bending process 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 multiple lead portions 110 with respect to the direction perpendicular to the stacking direction of multiple cell groups 100G for Examples 1 to 4 and the Comparative Example. In Table 1, the value in the "Average (°)" column indicates the average inclination (unit:°). The value in the "Maximum (°)" column indicates the maximum inclination (unit:°). The value in the "Minimum (°)" column indicates the minimum inclination (unit:°). [Table 1]

[0096] In Examples 1 to 4 and the Comparative Example, the average of the above-mentioned inclination was calculated by referring to all lead portions 110 provided in front of the cell stack 10. In calculating this average, the above-mentioned inclination with respect to the longitudinal direction of the battery cell 100 was measured. The longitudinal direction of the battery cell 100 is the first direction X in the example shown in Figure 4. In Examples 1 to 4, the average of the above-mentioned inclination was between 85.0° and 95.0°. In Examples 1 to 4, the maximum value of the above-mentioned inclination was 97.5° or less. In Examples 1 to 4, the minimum value of the above-mentioned inclination was 87.5° or more.

[0097] Table 2 shows the standard deviation of the positional displacement of the end faces of multiple lead portions 110 in a direction perpendicular to the stacking direction of multiple cell groups 100G for Examples 1 to 4 and the comparative example. In Table 2, the values ​​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 by referring to all lead portions 110 provided in front of the cell stack 10. In calculating the standard deviation, the above-mentioned displacement in the longitudinal direction of the battery cell 100 was measured. The longitudinal direction of the battery cell 100 is the first direction X in the example shown in Figure 4. In Examples 1 to 4, the above-mentioned standard deviation was between 0 and 2.50 mm.

[0099] A comparison of Examples 1 to 4 with the comparative example shows that when the lead portion 110 is folded in two stages 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 folded in one stage between adjacent cell groups 100G.

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

[0101] 10-cell stack 20 containment units 30 Voltage detection device 50 Battery Modules 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 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 line 330 connector 510 Jig 512 Central Clamp 514 Positive electrode clamp 516 Negative electrode clamp R reference plane X 1st direction Y Second direction Z 3rd direction

Claims

1. The device comprises multiple battery cells stacked in a predetermined direction, each having a positive electrode lead and a negative electrode lead. Two or more positive leads of two or more battery cells connected in parallel and two or more negative leads of two or more other battery cells connected in parallel are connected to each other on one side in a direction perpendicular to the predetermined direction of the plurality of battery cells to form a lead portion. Multiple lead portions are folded back on one side of the multiple battery cells, A battery module in which the average of the inclinations 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. The device comprises multiple battery cells stacked in a predetermined direction, each having a positive electrode lead and a negative electrode lead. Two or more positive leads of two or more battery cells connected in parallel and two or more negative leads of two or more other battery cells connected in parallel are connected to each other on one side in a direction perpendicular to the predetermined direction of the plurality of battery cells to form a lead portion. Multiple lead portions are folded back on one side of the multiple battery cells, A battery module in which the standard deviation of the positional displacement of the end faces of the plurality of lead portions in the direction perpendicular to the predetermined direction is 0 or more and 2.50 mm or less.

3. The battery module according to claim 1 or 2, wherein each of the plurality of lead portions is formed by two positive lead portions of two battery cells connected in parallel and two negative lead portions of two other battery cells connected in parallel.

4. Each of the plurality of battery cells has an outer casing that houses the battery elements, The two positive electrode leads are drawn out from one end located on one side of the outer casing material of the two battery cells and bent at the positive electrode bend. The two negative electrode leads are drawn out from one end located on one side of the outer casing of the two other battery cells and bent at the negative electrode bend. At least a portion of the bent tip of the two positive lead, which is bent by the bending of the positive electrode bend portion, and at least a portion of the bent tip of the two negative lead, which is bent by the bending of the negative electrode bend portion, overlap. The positive electrode bend portion is located at an equidistant distance from one end of the outer casing material of the two battery cells. The battery module according to claim 3, wherein the negative electrode bend is located equidistant from one end of the outer casing material of the two other battery cells.

5. The battery module according to claim 1, wherein the average of the inclinations of the end faces of the plurality of lead portions with respect to the direction perpendicular to the predetermined direction is 88.5° or more and 92.5° or less.

6. The battery module according to claim 2, wherein the standard deviation of the misalignment of the end faces of the plurality of lead portions in the direction perpendicular to the predetermined direction is 1.00 mm or less.

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