Battery module

Abstract

A battery module (100) comprises: a battery laminate (2) formed by laminating a plurality of batteries (20); and a separator (3) being disposed between adjacent batteries (20) and having a displacement absorbing member (36) which is in contact with a surface of one of the batteries (20), the surface intersecting the direction of lamination. The battery laminate (2) is disposed such that the positions of the two ends thereof in the direction of lamination of the battery laminate (2) are fixed.

Description

Technical Field

[0001] The present invention relates to a battery module.

Background Art

[0002] For example, as a power source that requires a high output voltage such as for vehicles, a battery module in which a plurality of batteries are electrically connected is known. Generally, each battery constituting the battery module deteriorates over time due to internal electrode bodies, electrolytes, etc., and bulges due to precipitation and oxidation of metal substances, resulting in a change in the outer shape. Regarding a battery module including such batteries, Patent Document 1 discloses a battery module including a battery laminate in which a plurality of batteries are laminated with an insulating sheet interposed therebetween, and end plates provided at both ends in the lamination direction of the battery laminate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Batteries expand and contract during charge and discharge. Also, batteries expand due to aging. When each battery in the battery module swells, in the stacking direction, each battery and the insulating sheet become in a state close to point contact from surface contact. The positions where each battery and the insulating sheet make point contact do not necessarily overlap at the same position when viewed from the stacking direction in a plane intersecting the stacking direction of the batteries, and as the contact position changes, each battery also rotates and displaces around an axis intersecting the stacking direction, and the relative displacement of each battery is not uniform and varies. In order to suppress the variation in the relative displacement of each battery, components for holding each battery with three-axis restraint have been required.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for suppressing variations in relative displacements of each battery while holding each battery in the battery module with one-axis restraint.

Means for Solving the Problems

[0006] A battery module according to an aspect of the present invention includes a battery stack in which a plurality of batteries are stacked, and a separator disposed between adjacent batteries and having a displacement absorbing material that contacts a surface intersecting the stacking direction of any one of the batteries, and fixes positions of both end portions of the battery stack in the stacking direction, and is characterized in that the battery stack is disposed.

Effects of the Invention

[0007] According to the present invention, it is possible to suppress variations in relative displacements of each battery while holding each battery in the battery module with one-axis restraint.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

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Figure 6

Figure 7

Modes for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments. The embodiments are illustrative rather than limiting the invention, and not all features and combinations thereof described in the embodiments are necessarily essential to the invention. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and duplicate explanations are omitted as appropriate. Also, the scales and shapes of the respective parts shown in each figure are set for convenience in order to facilitate the explanation, and are not to be construed restrictively unless otherwise specified. Further, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not represent any order or importance, but are for distinguishing one configuration from another. Also, in each drawing, some of the members that are not important in explaining the embodiments are omitted from the display.

[0010] (Embodiment) FIG. 1 is a perspective view showing the appearance of a battery module 100 according to an embodiment, and FIG. 2 is a horizontal cross-sectional view of a battery laminate 2 included in the battery module 100. The battery module 100 includes a rectangular parallelepiped housing 1, a battery laminate 2, a separator 3, and end separators 41 and 42. The battery module 100 holds the battery 20 with one-axis restraint using the separator 3 and suppresses the relative displacement of the battery 20 by the displacement absorbing material 36. In each figure, the stacking direction of the batteries 20 is defined as the X direction, the horizontal direction intersecting the X direction is the Y direction, and the vertical direction intersecting the X direction is the Z direction.

[0011] The housing 1 includes end plates 11, side plates 12, a base plate 13, and a cover plate 14. The end plates 11 are provided outside the batteries 20 located at both ends in the stacking direction of the batteries 20 in the battery laminate 2. The side plates 12 sandwich the end plates 11 and cover the side surfaces of the battery laminate 2. The base plate 13 is configured to cover the bottom of the battery laminate 2. The cover plate 14 covers the upper surface of the battery laminate 2.

[0012] The battery stack 2 is housed inside the housing 1. The battery stack 2 is configured by stacking a plurality of batteries 20 along one direction. A separator 3 formed of a resin material or the like is provided between each battery. The separator 3 electrically insulates each battery 20 of the battery stack 2. Since the separator 3 is incorporated into and integrated with the battery stack 2, it may be considered to constitute a part of the battery stack 2.

[0013] FIG. 3 is a perspective view showing the appearance of the separator 3 and the battery 20. The separator 3 includes a rectangular plate-shaped substrate 30, a holder portion 31, a guide portion 32, a fitting portion 33, and a displacement absorbing material 36. The holder portion 31 is composed of wall bodies rising from the bottom side of the substrate 30 and three side portions at both ends in the horizontal direction toward one side of the substrate 30, and the upper part is open.

[0014] The guide portion 32 corresponds to the holder portion 31 and is composed of wall bodies rising from the bottom side of the substrate 30 and three side portions at both ends in the horizontal direction toward the other side of the substrate 30, and the upper part is open. The holder portion 31 has smaller outer dimensions than the guide portion 32 and is fitted inside the guide portion 32 of the adjacent separator 3.

[0015] FIG. 4 is a perspective view seen from the guide portion 32 side of the separator 3. The fitting portion 33 is provided at the center of the side portion on the upper side of the substrate 30 and has a first fitting portion 33a and a second fitting portion 33b. The first fitting portion 33a is composed of wall bodies provided at both ends in the upper and Y directions and is provided so as to rise from the center of the side portion on the upper side of the substrate 30 toward the same side as the holder portion 31. The second fitting portion 33b is similarly composed of wall bodies provided at both ends in the upper and Y directions and is provided so as to rise from the center of the side portion on the upper side of the substrate 30 toward the same side as the guide portion 32. The first fitting portion 33a has smaller outer dimensions than the second fitting portion 33b and is fitted inside the second fitting portion 33b provided on the adjacent separator 3.

[0016] On the side of the guide portion 32 of the substrate 30 of the separator 3, an air passage forming portion 34 is formed. The air passage forming portion 34 is composed of a plurality of ridges protruding from the surface of the substrate 30 on the guide portion 32 side, and air passages 35 are formed between the respective ridges.

[0017] Inside the holder portion 31 of the separator 3, a plate-shaped displacement absorber 36 is provided. The battery 20 contacts the displacement absorber 36 and is fitted inside the holder portion 31. The displacement absorber 36 is formed of a resin material or the like having lower rigidity than other parts of the separator 3, and is compressed and deformed in the X direction to absorb the displacement due to the swelling of the battery 20.

[0018] Each battery 20 is, for example, a rechargeable secondary battery such as a lithium ion battery, a nickel-hydrogen battery, or a nickel-cadmium battery. Also, each battery 20 is a so-called rectangular battery and has a flat rectangular parallelepiped-shaped exterior can 21 (see FIG. 3). A substantially rectangular opening (not shown) is provided in one surface of the exterior can 21, and an electrode body, an electrolytic solution, etc. are accommodated in the exterior can 21 through this opening. A sealing plate 21a for closing the opening is provided at the opening of the exterior can 21.

[0019] On the sealing plate 21a, the positive output terminal 22 is arranged near one end in the longitudinal direction, and the negative output terminal 22 is arranged near the other end. Each of the pair of output terminals 22 is electrically connected to the positive electrode plate and the negative electrode plate constituting the electrode body. Each output terminal 22 is inserted into a through hole (not shown) formed in the sealing plate 21a. An insulating seal member (not shown) is interposed between each output terminal 22 and each through hole. In the following description, for convenience, the sealing plate 21a is taken as the upper surface of the battery 20, and the bottom surface of the exterior can 21 facing the sealing plate 21a is taken as the lower surface of the battery 20.

[0020] Further, the battery 20 has two main surfaces that connect the upper surface and the lower surface. This main surface is the surface with the largest area among the six surfaces of the battery 20. The main surface is a long side surface connected to the long sides of the upper surface and the lower surface. The remaining two surfaces excluding the upper surface, the lower surface, and the two main surfaces are the side surfaces of the battery 20. This side surface is a pair of short side surfaces connected to the short sides of the upper surface and the lower surface. These directions and positions are defined for convenience. Therefore, for example, the portion defined as the upper surface in the present invention does not necessarily mean that it is located above the portion defined as the lower surface.

[0021] A valve portion 24 is provided between a pair of output terminals 22 on the sealing plate 21a. The valve portion 24 is also called a safety valve and is a mechanism for each battery 20 to eject gas inside the battery. The valve portion 24 is configured to open when the internal pressure of the outer can 21 rises above a predetermined value and release the internal gas. The valve portion 24 is composed of, for example, a thin-walled portion provided on a part of the sealing plate 21a and having a thickness thinner than other parts, and a linear groove formed on the surface of this thin-walled portion. In this configuration, when the internal pressure of the outer can 21 rises, the thin-walled portion tears starting from the groove, thereby opening the valve.

[0022] A plurality of batteries 20 are stacked at a predetermined interval such that the main surfaces of adjacent batteries 20 face each other. Note that "stacking" means arranging a plurality of members in an arbitrary one direction. Therefore, the stacking of the batteries 20 includes arranging a plurality of batteries 20 horizontally. In the present embodiment, the batteries 20 are stacked horizontally. Each battery 20 is arranged such that the output terminals 22 face the same direction. In each battery 20 of the present embodiment, the output terminals 22 are arranged to face upward in the vertical direction.

[0023] The end separators 41 and 42 are provided between the battery 20 located at the end in the stacking direction of the batteries 20 in the battery stack 2 and the end plate 11 (see FIG. 2). The end separator 41 is provided on one end side in the stacking direction of the batteries 20 and has a substrate 41a, a guide portion 41b, and an air passage forming portion 41c corresponding to the substrate 30, the guide portion 32, and the air passage forming portion 34 of the separator 3.

[0024] The end separator 42 is provided on the other end side in the stacking direction of the battery 20, and has a substrate 42a and a holder portion 42b corresponding to the substrate 30 and the holder portion 31 of the separator 3. Further, a displacement absorbing material 36 is provided inside the holder portion 42b of the end separator 42. Incidentally, the end separators 41 and 42 may be appropriately provided with members corresponding to the fitting portions 33 provided on the separator 3, and these members may be fitted into the fitting portions 33 of the adjacent separators 3.

[0025] The two end plates 11 provided at both ends in the stacking direction of the battery 20 in the battery stack 2 are attached to the side plate 12 and the base plate 13. The battery stack 2, the separator 3, and the end separators 41 and 42 are arranged between the two end plates 11 so that the adjacent parts in the stacking direction are in contact with each other, and are held by uniaxial restraint (restraint in the X direction). Further, the battery stack 2, the separator 3, and the end separators 41 and 42 may be arranged between the two end plates 11 in a state where the displacement absorbing material 36 is slightly compressed and deformed, so as to increase the internal applied pressure of the uniaxial restraint.

[0026] Next, the operation of the battery module 100 will be described with respect to the generation of displacement due to the swelling of the battery 20. FIG. 5 is a schematic diagram for explaining the displacement of each battery when the displacement absorbing material 36 is provided. FIG. 6 is a schematic diagram for explaining the displacement of each battery when the displacement absorbing material 36 is not provided as a comparative example. FIGS. 5 and 6 correspond to a plan view of the battery stack 2 viewed from above. As described above, in each battery 20, the internal electrode body, electrolyte, etc. deteriorate over time, and bulges due to the precipitation and oxidation of metal substances, resulting in a change in the outer shape. Each battery 20 is a prismatic battery and has a flat rectangular parallelepiped outer can 21. Among the six surfaces of the battery 20, the main surface with the largest area deforms so as to bulge.

[0027] The two end plates 11 are attached to the side plates 12 and the base plate 13, whereby the battery stack 2, the separator 3, and the end separators 41 and 42 are held under uniaxial restraint (restraint in the X direction). The battery stack 2, the separator 3, and the end separators 41 and 42 are incorporated between the two end plates 11 with the displacement absorber 36 slightly compressed and deformed, thereby increasing the internal applied pressure of the uniaxial restraint.

[0028] As shown in FIG. 5, when deformation occurs in the stacking direction due to the swelling of the main plane of the battery 20, the displacement absorber 36 provided in the separator 3 and the like elastically compresses and deforms, and the load acting in the stacking direction is dispersed within the contact surface between the main plane and the displacement absorber 36. Since the load acting on the battery 20 is dispersed at the contact surface, the battery 20 returns to its original posture. As a result, the battery module 100 can suppress the variation in the relative displacement of each battery 20 by holding each battery 20 in the battery module 100 under uniaxial restraint and allowing the battery 20 to return to its original posture even if the battery 20 swells due to aging deterioration.

[0029] In the comparative example shown in FIG. 6, when deformation occurs in the stacking direction due to the swelling of the main plane of the battery 20, the battery 20 is displaced according to the position of the contact point, the posture of each battery changes, and variation in the relative displacement of each battery 20 occurs.

[0030] The separator 3 is provided with a holder portion 31 for fitting the battery 20 on one side in the stacking direction, and a guide portion 32 on the other side into which the holder portion 31 of the adjacent separator is fitted. The battery module 100 can suppress the displacement of the battery 20 in the direction intersecting the stacking direction by fitting the holder portion 31 and the guide portion 32 between adjacent separators 3.

[0031] Since the displacement absorber 36 is provided inside the holder portion 31, when the battery 20 is deformed, the holding property of the battery 20 in the separator 3 can be ensured by the fitting between the holder portion 31 and the battery 20 and the contact surface between the battery 20 and the displacement absorber 36.

[0032] The separator 3 is provided with an air passage forming portion 34 on the side of the guide portion 32. In the battery module 100, an air passage 35 for air-cooling the battery 20 can be secured with the battery 20 in contact with the air passage forming portion 34.

[0033] (Modification example) FIG. 7 is a schematic diagram for explaining the battery laminate 2 according to the modification example. FIG. 7 corresponds to a plan view of the battery laminate 2 as seen from above. In the battery laminate 2 according to the modification example, a displacement absorbing material 36 is provided on the side of the guide portion 32 of the substrate 30 in the separator 3. The battery 20 contacts the displacement absorbing material 36 provided on the side of the guide portion 32 of the adjacent separator 3 while being held by the holder portion 31 of one separator 3. Thereby, when the battery 20 bulges, the battery 20 and the displacement absorbing material 36 come into surface contact, so that the contact area of the battery 20 with the adjacent separator 3 can be secured.

[0034] In the battery laminate 2 according to the modification example, the air passage forming portion 34 is provided on the side of the holder portion 31 of the substrate 30 in the separator 3, and an air passage 35 for air-cooling the battery 20 can be secured with the battery 20 in contact with the air passage forming portion 34.

[0035] The embodiments of the present invention have been described above. These embodiments are illustrative, and it is understood by those skilled in the art that various modifications and changes are possible within the scope of the claims of the present invention, and such modifications and changes are also within the scope of the claims of the present invention. Therefore, the descriptions and drawings in this specification should be treated as illustrative rather than restrictive.

[0036] Note that the embodiments may be specified by the following items. [Item 1] A battery laminate (2) in which a plurality of batteries (20) are laminated, A separator (3) disposed between adjacent ones of the batteries (20) and having a displacement absorbing material (36) that contacts a surface intersecting the stacking direction of any one of the batteries (20). A battery module (100) characterized in that positions of both end portions of the battery laminate (2) in the stacking direction are fixed and the battery laminate (2) is disposed therein. Thereby, the battery module (100) can suppress variations in relative displacement of each battery (20) while holding each battery (20) in the battery module (100) with one-axis restraint. [Item 2] The separator (3) has a holder portion (31) for fitting the battery (20) on one side in the stacking direction and a guide portion (32) into which the holder portion (31) of an adjacent separator (3) is fitted on the other side. The battery module (100) according to Item 1, characterized in that. Thereby, the battery module (100) can suppress displacement of the battery (20) in a direction intersecting the stacking direction by fitting the holder portion (31) and the guide portion (32) between adjacent separators (3). [Item 3] The displacement absorbing material is provided on the one side. The battery module (100) according to Item 2, characterized in that. Thereby, the battery module (100) can ensure the holding property of the battery (20) in the separator (3) by the fitting between the holder portion (31) and the battery (20) and the contact surface between the battery (20) and the displacement absorbing material (36). [Item 4] An air passage (35) is formed between the other side of the separator (3) and the battery (20) disposed on the other side. The battery module (100) according to Item 3, characterized in that. Thereby, the battery module (100) can secure an air passage (35) for air-cooling the battery (20). [Item 5] The displacement absorbing material is provided on the other side. The battery module (100) according to Item 2, characterized in that. Thereby, the battery module (100) can secure the contact area of the battery (20) with adjacent separators (3).

Explanation of Signs

[0037] 2 Battery laminate, 20 Battery, 3 Separator, 31 Holder part, 32 Guide part, 35 Air passage, 36 Displacement absorber, 100 Battery module.

Claims

1. A battery stack in which a plurality of batteries are stacked, A separator disposed between adjacent ones of the batteries and having a displacement absorber that contacts a surface intersecting the stacking direction of any one of the batteries, Comprising: Fixing the positions of both end portions of the battery stack in the stacking direction, where the battery stack is disposed, The separator is composed of a substrate intersecting the stacking direction, a wall rising from a side portion of the substrate toward one side in the stacking direction, a holder portion for fitting the battery on the one side, and a wall rising from a side portion of the substrate toward the other side in the stacking direction, and has a guide portion into which the holder portion of the separator adjacent to the other side is fitted. A gap is provided between the wall constituting the holder portion and the wall constituting the guide portion of the adjacent separator. The battery stack and the separator are uniaxially constrained in the stacking direction, and the battery module is characterized by this.

2. The battery module according to claim 1, wherein the displacement absorber is provided on the one side.

3. The battery module according to claim 2, wherein an air passage is formed between the other side of the separator and the battery disposed on the other side.

4. The battery module according to claim 1, wherein the displacement absorber is provided on the other side.

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