JP2017117633A - Method of manufacturing battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a battery pack capable of applying an appropriate constraining load to a unit cell, while making the length of the battery pack constant.SOLUTION: A method of manufacturing a battery pack includes a step of laminating a plurality of unit cells 10 having an electrode body 20, and a case body 31 for housing the electrode body 20, and a spacer 51 interposed between adjoining unit cells 10, and a step of applying a load in the lamination direction of the unit cells 10 to a laminate obtained by the step of laminating the plurality of unit cells 10 and spacers 51. In the plan view from the lamination direction of the unit cells 10, the case body 31 includes a first region 110 facing the reaction part of the electrode body 20, and a second region 116 not facing the reaction part of the electrode body 20. During the step of applying a load to the laminate, the case body 31 deforms to become short in the lamination direction of the unit cells 10 in at least a part of the second region 116, and comes into contact with the electrode body 20 in the first region 110.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method for manufacturing an assembled battery.

  Regarding a conventional assembled battery, for example, Japanese Unexamined Patent Application Publication No. 2014-157747 (Patent Document 1) discloses an assembled battery and a battery module for the purpose of appropriately maintaining the surface pressure applied to each single battery. Has been.

  The assembled battery disclosed in Patent Document 1 is a plurality of chargeable / dischargeable cells that are arranged in a predetermined direction while being electrically connected to each other, and are restrained in a state where a load is applied in the arrangement direction. And a shock-absorbing plate that has a contact surface that contacts the container side wall of the unit cell and is disposed in at least one of the gaps between the plurality of arranged unit cells. On the contact surface of the buffer plate, a deformable portion that allows the deformation of the unit cell and a non-deformed portion that does not permit the deformation of the unit cell are formed.

JP 2014-157747 A International Publication No. 2011/158313 Japanese Patent Laying-Open No. 2015-125859

  As disclosed in Patent Document 1 described above, an assembled battery obtained by stacking a plurality of unit cells via a spacer and applying a load along the stacking direction of the unit cells to the obtained stack is known. It has been.

  In the manufacture of such an assembled battery, the length of the assembled battery in the stacking direction of the single cells (hereinafter, also simply referred to as “the length of the assembled battery”) varies due to the variation in the thickness of the single cells. . When the length of the assembled battery is made constant, the length of the assembled battery is set so that the necessary lower limit load is applied to the single battery with reference to the case where the thickness of the single battery is small. However, when the assembled battery is manufactured by applying the length of the assembled battery set in such a manner to the case where the thickness of the single battery is large, there is a concern that an excessive restraining load is applied to the single battery.

  Accordingly, an object of the present invention is to solve the above-described problem, and to provide a method of manufacturing an assembled battery that can apply an appropriate restraining load to a single cell while keeping the length of the assembled battery constant. is there.

  A method of manufacturing an assembled battery according to the present invention includes a step of laminating a plurality of unit cells having an electrode body and a case body that accommodates the electrode body, and a spacer disposed between adjacent unit cells, A step of applying a load in the stacking direction of the single cells to the stack obtained by the step of stacking the plurality of single cells and the spacer. The case body includes a first region facing the reaction part of the electrode body and a second region not facing the reaction part of the electrode body in a plan view as viewed from the stacking direction of the unit cells. During the step of applying a load to the stacked body, the case body is deformed so as to be shorter in the stacking direction of the unit cells in at least a part of the second region, and contacts the electrode body in the first region.

  According to the assembled battery manufacturing method thus configured, even when the unit cell is thick, the case body does not face the reaction part of the electrode body during the step of applying a load to the stacked body. By deforming at least part of the second region, it is possible to suppress an excessive restraining load from being applied to the reaction part of the unit cell. On the other hand, during the step of applying a load to the laminated body, the case body contacts the electrode body in the first region facing the reaction section of the electrode body, thereby applying a necessary restraining load to the reaction section of the unit cell. Can do. Therefore, according to the present invention, an appropriate restraining load can be applied to the unit cell while keeping the length of the assembled battery constant.

  As described above, according to the present invention, it is possible to provide a method of manufacturing an assembled battery that can apply an appropriate restraining load to a single cell while keeping the length of the assembled battery constant.

It is a side view which shows the assembled battery manufactured using the manufacturing method of the assembled battery in embodiment of this invention. It is sectional drawing which shows the single battery which comprises the assembled battery in FIG. FIG. 3 is an exploded view showing an electrode body housed in a single battery in FIG. 2. It is a perspective view which shows the electrode body accommodated in the single battery in FIG. It is a side view which shows the process of the manufacturing method of the assembled battery in embodiment of this invention. It is sectional drawing which shows the process of the manufacturing method of the assembled battery in embodiment of this invention. It is a figure for demonstrating the 1st area | region and 2nd area | region of a case body. It is a figure for demonstrating the 1st area | region and 2nd area | region of a case body. It is a figure for demonstrating the 1st area | region and 2nd area | region of a case body. It is a figure which shows the spacer used in the manufacturing method of the assembled battery in embodiment of this invention. It is sectional drawing which shows the spacer along the XI-XI line | wire in FIG. It is a side view which shows the process of the manufacturing method of the assembled battery in a comparative example. It is a side view which shows the process of the manufacturing method of the assembled battery in a comparative example. It is a graph which shows the relationship between the variation | change_quantity of stack length, and a restraint load. It is sectional drawing which shows the process of adjusting the retention strength of an electrode body in the manufacturing method of the assembled battery in embodiment of this invention. It is a graph which shows the relationship between the deformation amount (stroke) of a case body, and the load which generate | occur | produces in an electrode body. It is the front view which looked at the restraint surface of a case body from the front.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

  FIG. 1 is a side view showing an assembled battery manufactured by using the assembled battery manufacturing method according to the embodiment of the present invention. FIG. 2 is a cross-sectional view showing a unit cell constituting the assembled battery in FIG. With reference to FIG. 1 and FIG. 2, the structure of the assembled battery 100 manufactured using the manufacturing method of the assembled battery in this Embodiment is demonstrated first.

  The assembled battery 100 is mounted on a hybrid vehicle, an electric vehicle, or the like that uses an internal combustion engine such as a gasoline engine or a diesel engine and a motor supplied with power from a chargeable / dischargeable battery.

  The assembled battery 100 includes a plurality of single cells 10, a plurality of spacers 51, an end plate 41 and an end plate 42. The cell 10 is comprised from the lithium ion battery as a typical example.

  The plurality of unit cells 10 are stacked in the direction indicated by the arrow 102 via the spacer 51 (hereinafter, the direction indicated by the arrow 102 is also referred to as “the stacking direction of the unit cells 10”). The unit cell 10 has a substantially rectangular parallelepiped thin plate shape.

  The unit cell 10 has a positive electrode terminal 34 and a negative electrode terminal 35. The positive electrode terminal 34 and the negative electrode terminal 35 are electrically connected in series between the plurality of single cells 10.

  An end plate 41 and an end plate 42 are respectively disposed on both sides of the plurality of unit cells 10 stacked. The end plate 41 and the end plate 42 are coupled to each other by a coupling member (not shown). With such a configuration, the plurality of unit cells 10 are integrally held in a state of receiving a restraining load along the stacking direction of the unit cells 10.

  FIG. 3 is an exploded view showing an electrode body housed in the unit cell in FIG. FIG. 4 is a perspective view showing an electrode body housed in the unit cell in FIG. With reference to FIG. 2 to FIG. 4, the cell 10 includes an electrode body 20, a case body 31, a current collecting terminal 36 and a current collecting terminal 37.

  The case body 31 makes an appearance of the unit cell 10. The case body 31 is made of a metal such as aluminum. The case body 31 has a constraining surface 31a. The constraining surface 31a has the largest area among a plurality of side surfaces forming the appearance of the unit cell 10. The restraining surface 31a has a rectangular shape. The plurality of unit cells 10 are stacked so that the constraining surfaces 31a face each other between the unit cells 10 adjacent to each other.

  In the present embodiment, the case body 31 is configured by combining the main body portion 32 and the lid portion 33. The main body 32 has a substantially rectangular parallelepiped housing shape opened in one direction. The lid 33 is provided so as to close the opening of the main body 32. A positive electrode terminal 34 and a negative electrode terminal 35 are attached to the lid portion 33.

  The electrode body 20 is accommodated in the case body 31 together with the electrolytic solution. The electrode body 20 includes a positive electrode sheet 21 and a negative electrode sheet 26 that is superimposed on the positive electrode sheet 21 with a separator 29 interposed therebetween.

  The positive electrode sheet 21 is formed from an aluminum foil having a substantially rectangular shape. A paste 22 containing a positive electrode active material is applied to both surfaces of the positive electrode sheet 21. On one peripheral edge extending in the longitudinal direction of the positive electrode sheet 21, a paste non-applied portion 23 not applied with the paste 22 is formed extending in a band shape.

  The negative electrode sheet 26 is formed from a copper foil having the same shape as the positive electrode sheet 21. A paste 27 containing a negative electrode active material is applied to both surfaces of the negative electrode sheet 26. On one peripheral edge extending in the longitudinal direction of the negative electrode sheet 26, a paste non-applied portion 28 to which the paste 27 is not applied is formed extending in a band shape.

  The separator 29 has a substantially rectangular shape that is shorter than the positive electrode sheet 21 and the negative electrode sheet 26 in the short direction. As the separator 29, for example, a porous polypropylene resin sheet can be used.

  The positive electrode sheet 21, the negative electrode sheet 26, and the two separators 29 are superposed in the order of the separator 29, the negative electrode sheet 26, the separator 29, and the positive electrode sheet 21. At this time, the region where the paste 22 is applied to the positive electrode sheet 21 and the region where the paste 27 is applied to the negative electrode sheet 26 face each other via the separator 29. The paste uncoated portion 23 of the positive electrode sheet 21 is exposed from one end side extending in the longitudinal direction of the separator 29, and the paste uncoated portion 28 of the negative electrode sheet 26 is exposed from the other end side extending in the longitudinal direction of the separator 29. To do.

  The electrode body 20 is a winding type, and a laminated body composed of a positive electrode sheet 21, a negative electrode sheet 26, and two separators 29 is wound around a virtual central axis 101 shown in FIG. Is formed. The laminate is wound so that a cross-sectional shape when cut along a plane orthogonal to the central axis 101 is a track shape (a shape in which a rectangle and two semicircles are combined). The electrode body 20 configured as described above has a pair of side surfaces 20a extending in a planar shape on both sides of the central axis 101.

  In the state of the laminated body in which each sheet is wound, the position where the paste non-applied portions 23 of the positive electrode sheet 21 overlap each other is connected to the positive electrode terminal 34 via the current collecting terminal 36, and the paste of the negative electrode sheet 26 is not pasted. The position where the coating part 28 overlaps in multiple layers is connected to the negative electrode terminal 35 via the current collecting terminal 37.

  FIG. 5 is a side view showing the steps of the assembled battery manufacturing method according to the embodiment of the present invention. FIG. 6 is a cross-sectional view showing the steps of the assembled battery manufacturing method according to the embodiment of the present invention. Then, the manufacturing method of the assembled battery in embodiment of this invention is demonstrated.

  Referring to FIGS. 5 and 6, the method for manufacturing the assembled battery in the present embodiment includes a step of laminating a plurality of unit cells 10 and spacers 51 arranged between unit cells 10 adjacent to each other, A step of applying a load in the stacking direction of the single cells 10 to the stacked body 12 obtained by the stacking step. During the step of applying a load to the stacked body 12, the case body 31 is deformed so as to be shorter in the stacking direction of the unit cells 10 in at least a part of the second region 116, and the electrode body 20 is formed in the first region 110. Contact with.

  7 to 9 are diagrams for explaining the first region and the second region of the case body. 7 shows a plan view of the constraining surface 31a of the case body 31, FIG. 8 shows a front view and a side view of the electrode body 20, and FIG. 9 shows an IX in FIG. A cross-sectional view of the electrode body 20 along the line -IX is shown.

  7 to 9, the case body 31 includes a first region 110 facing the reaction portion of the electrode body 20 and the reaction portion of the electrode body 20 in a plan view viewed from the stacking direction of the unit cells 10. And a second region 116 that does not face each other. The first region 110 and the second region 116 are defined on the restraining surface 31 a of the case body 31.

  More specifically, the reaction part of the electrode body 20 means that the paste 22 containing the positive electrode active material and the paste 27 containing the negative electrode active material in the cross section of the electrode body 20 shown in FIG. This is a portion that overlaps in the stacking direction of the sheet 21 and the negative electrode sheet 26.

  When the constraining surface 31a is viewed in plan, the first region 110 has a rectangular shape. The first region 110 is defined at the center of the constraining surface 31a having a rectangular shape. As shown in FIGS. 7 and 9, the range of one side in the horizontal direction of the first region 110 is determined by the width 112 of the reaction portion of the electrode body 20. As shown in FIGS. 7 and 8, the range of one side in the vertical direction of the first region 110 is determined by the length 114 (electrode body existence portion) corresponding to the side surface 20 a of the reaction portion of the electrode body 20. It is done.

  The second region 116 has a frame shape extending in a strip shape along the periphery of the first region 110. The second region 116 is defined on the peripheral edge of the constraining surface 31a having a rectangular shape.

  FIG. 10 is a diagram showing spacers used in the method for manufacturing an assembled battery in the embodiment of the present invention. FIG. 11 is a cross-sectional view showing the spacer along the line XI-XI in FIG.

  Referring to FIGS. 5 to 11, the spacer 51 has a substantially rectangular parallelepiped thin plate shape in which the stacking direction of the unit cells 10 is the thickness direction as a whole. The spacer 51 has a surface 51a. The spacer 51 is disposed between the adjacent unit cells 10 such that the surface 51a faces the constraining surface 31a of the unit cell 10 (case body 31). The surface 51a has a rectangular shape corresponding to the constraining surface 31a.

  A recess 52 is formed in the spacer 51. The recess 52 is formed so as to be recessed from the surface 51 a in the thickness direction of the spacer 51. When the front surface 51 a is viewed from the front, the recess 52 has a rectangular shape corresponding to the first region 110. The recessed part 52 is formed in the center part of the surface 51a which has a rectangular shape.

  The spacer 51 has a protrusion 53. The protruding portion 53 is provided so as to protrude from the bottom surface of the recess 52, and a surface 51a is formed at the protruding tip. The protrusion 53 has a frame shape extending in a band shape along the periphery of the recess 52.

  By inserting the spacer 51 configured in this manner between the adjacent unit cells 10, the second region 116 of the case body 31 that contacts the protruding portion 53 during the step of applying a restraining load to the stacked body 12. This part is plastically deformed into a concave shape in the stacking direction of the unit cells 10. Further, the first region 110 of the case body 31 applies a restraining load as shown in the surface pressure distribution 141 in FIG. 6 to the electrode body 20 while being in contact with the electrode body 20.

  Then, the effect produced by the manufacturing method of the assembled body in the embodiment of the present invention will be described with reference to a comparative example.

  12 and 13 are side views showing the steps of the method for manufacturing the assembled battery in the comparative example. With reference to FIG. 12 and FIG. 13, in the present comparative example, a spacer 56 having a substantially rectangular parallelepiped thin plate shape is disposed between adjacent unit cells 10. The spacer 56 is not formed with the recess 52 in the spacer 51.

  The unit cell 10 has a small thickness and a large thickness due to manufacturing tolerances. When a certain restraining load is applied in the case where the unit cell 10 having a large thickness is used (the upper diagram in FIG. 12) and in the case where the unit cell 10 having a small thickness is used (the lower diagram in FIG. 12), The variation 121 occurs in the length of the battery pack 100 in the stacking direction of 10 (the stack length of the unit cells 10).

  On the other hand, for the unit cell 10 (electrode body 20), the upper limit value of the restraint load is determined as the upper limit load capable of maintaining the battery performance, and the lower limit value of the restraint load is necessary for the electrode body 20 with respect to the case body 31. It is defined as a lower limit load that can generate a holding force. As shown in FIG. 13, when the stack length is constant (small fluctuation), the stack length is shortened until the lower limit load is generated when the unit cell 10 having a small thickness is used. However, when the unit cell 10 having a large thickness is used, if a load is applied until the stack length is reached, an excessive restraining load is applied to the unit cell 10 and the performance of the unit cell 10 may not be sufficiently exhibited. There is.

  FIG. 14 is a graph showing the relationship between the stack length variation and the restraint load. Referring to FIG. 14, the relationship between the stack length variation and the restraint load in the comparative example in FIGS. 12 and 13 is indicated by a curve 136, and the stack length in the method for manufacturing the assembled battery in the present embodiment is shown. The relationship between the fluctuation amount and the constraint load is shown by a curve 131. In the graph, the constraint load A is a predetermined lower limit value of the constraint load, and the constraint load C is an upper limit value of the predetermined constraint load.

  In the comparative example in FIGS. 12 and 13, when the unit cell 10 having a large thickness is used, if the load is increased until the set stack length fluctuation amount 132 is obtained, the restraint load larger than the restraint load C is obtained. D is added to the cell 10.

  Referring to FIGS. 5, 6, and 14, on the other hand, in the assembled battery manufacturing method according to the present embodiment, case body 31 has the second region during the step of applying a load to laminated body 12. At least part of 116 is deformed so as to be shorter in the stacking direction of the unit cells 10, and contacts the electrode body 20 in the first region 110.

  According to such a configuration, compared to the comparative example in which a load is positively applied to the reaction part of the electrode body 20, the rise of the restraint load with respect to the stack length variation (generated load per unit variation) The case body 31 pressed in the second region 116 indirectly applies a load to the reaction part of the electrode body 20. Thereby, the lower limit load required for holding the electrode body 20 in the case body 31 can be applied to the unit cell 10. Further, even when the load is increased until the stack length variation 132 set based on the case where the unit cell 10 having a small thickness and the unit cell 10 having a small thickness is used is obtained, the electrode body 20 It is possible to suppress an excessive restraint load from being applied to the reaction part (constraint load B <constraint load C (upper limit value) in FIG. 14).

  In addition, in this Embodiment, although the winding type electrode body 20 was demonstrated, it is not restricted to this, The laminated body which repeated the positive electrode sheet, the separator, and the negative electrode sheet may be sufficient. In this case, one side in the vertical direction and the horizontal direction of the first region 110 of the case body 31 is defined by the width of the reaction portion of the electrode body 20.

  Next, a method for adjusting the holding force of the electrode body 20 in the method for manufacturing an assembled battery in the present embodiment will be described.

  FIG. 15 is a cross-sectional view showing a step of adjusting the holding force of the electrode body in the method for manufacturing an assembled battery according to the embodiment of the present invention. FIG. 16 is a graph showing the relationship between the deformation amount (stroke) of the case body and the load generated on the electrode body.

  Referring to FIGS. 15 and 16, the holding force of electrode body 20 is proportional to the surface pressure acting on electrode body 20, the contact area of case body 31 and electrode body 20, and the coefficient of friction. As shown in FIG. 16, the load generated on the electrode body 20 increases as the plate thickness of the case body 31 increases. Therefore, when the plate thickness of the case body 31 is increased, the surface pressure distribution acting on the electrode body 20 is increased. 142 becomes larger.

  Therefore, the holding force of the electrode body 20 can be adjusted by changing the plate thickness of the case body 31.

  FIG. 17 is a front view of the restraining surface of the case body as viewed from the front. As a method of increasing the average surface pressure acting on the electrode body 20, as a material of the case body 31, a method of selecting a material having high tensile strength, or as shown in FIG. There are ways to increase it. In these cases, the surface pressure distribution changes, and at the same time, the deformation amount of the case body 31 changes, and the frictional force (friction coefficient) between the case body 31 and the electrode body 20 can be adjusted.

  According to the method for manufacturing an assembled battery in the embodiment of the present invention described above, it is possible to apply an appropriate restraining load to the unit cell 10 while keeping the length of the assembled battery 100 constant.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is mainly used for manufacturing an assembled battery obtained by stacking a plurality of unit cells.

  100 assembled battery, 10 unit cell, 12 laminate, 20 electrode body, 20a side surface, 21 positive electrode sheet, 22, 27 paste, 23, 28 uncoated part, 26 negative electrode sheet, 29 separator, 31 case body, 31a restraint surface, 32 Main body part, 33 Lid part, 34 Positive electrode terminal, 35 Negative electrode terminal, 36, 37 Current collecting terminal, 41, 42 End plate, 51, 56 Spacer, 51a Surface, 52 Recessed part, 53 Protruding part, 101 Central axis, 110 1st 1 region, 112 width, 114 length, 116 2nd region, 121 variation, 131, 136 curve, 132 stack length variation, 141, 142 contact pressure distribution.

Claims (1)

Laminating a plurality of unit cells having an electrode body and a case body that accommodates the electrode body, and a spacer disposed between the unit cells adjacent to each other;
A step of applying a load in the stacking direction of the unit cells, with respect to the stack obtained by the step of stacking the plurality of unit cells and the spacer,
The case body includes a first region facing the reaction part of the electrode body and a second region not facing the reaction part of the electrode body in a plan view as viewed from the stacking direction of the unit cells,
In the step of applying a load to the stacked body, the case body is deformed so as to be short in the stacking direction of the unit cells in at least a part of the second region, and the electrode body in the first region. A method for producing an assembled battery in contact with

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