Battery Module

Abstract

A battery module (100) comprises: a battery layered body (2) in which a plurality of batteries (20) are layered; an end plate (11) provided on the outer side of an end-part battery (20) in the layering direction of the plurality of batteries (20); and an end separator (4) provided between the end-part battery (20) and the end plate (11), the end separator (4) having a deformation-allowing part (41) which is formed in one portion in the layering direction and in which deformation due to creep is greater than in other portions.

Description

[Technical field]

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

[0002] Battery modules in which multiple batteries are electrically connected are known as power sources that require high output voltages, such as for vehicles. In general, the internal electrodes and electrolytes of each battery that constitutes a battery module deteriorate over time, and the batteries swell and change in external shape due to deposition and oxidation of metallic substances. Regarding battery modules that include such batteries, Patent Document 1 discloses a battery module that includes a battery stack in which multiple batteries are stacked with insulating sheets interposed between each battery, and end plates provided at both ends of the battery stack in the stacking direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 161655 Summary of the Invention [Problem to be solved by the invention]

[0004] As the dimensions of each battery in a battery module increase in the stacking direction over time, loads due to dimensional changes in all of the batteries are applied to the end plates at both ends of the battery stack, and this reaction force is applied to each battery, which can cause malfunctions such as battery damage.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for reducing the reaction force generated in the stacking direction within a battery module. [Means for solving the problem]

[0006] A battery module according to one embodiment of the present invention is characterized in comprising: a battery stack comprising a plurality of stacked batteries; an end plate provided on the outside of an end battery in the stacking direction of the plurality of batteries; and an end separator provided between the end battery and the end plate, the end separator being formed in a portion of the stacking direction and having a deformation-allowing portion that is subject to greater deformation due to creep than other portions. Effect of the Invention

[0007] According to the present invention, the safety of the battery module can be improved. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an external appearance of a battery module according to an embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of a portion of the battery module. [Diagram 3] FIG. 2 is a perspective view of the end separator as viewed from the battery side. [Figure 4] FIG. 2 is a cross-sectional side view of an end separator. [Diagram 5] FIG. 4 is a schematic diagram for explaining a positional relationship within a battery module at an initial stage. [Figure 6] 1 is a schematic diagram for explaining a state in which a battery in a battery module is swollen in the stacking direction due to aging deterioration. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. The same or equivalent components, members, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation, and are not to be interpreted as being limiting unless otherwise specified. In addition, 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 intended to distinguish one configuration from another. In addition, some of the members that are not important in explaining the embodiment in each drawing are omitted.

[0010] (Embodiment) Fig. 1 is a perspective view showing the appearance of a battery module 100 according to an embodiment, and Fig. 2 is an exploded perspective view of a portion of the battery module 100. The battery module 100 includes a rectangular parallelepiped housing 1, a battery stack 2, a separator 3, and an end separator 4. The battery module 100 has a deformable portion in the end separator 4 that is subject to greater deformation due to creep in the stacking direction than other portions, thereby reducing the reaction force acting on the battery due to creep in the deformable portion.

[0011] The housing 1 comprises end plates 11, side plates 12, a base plate 13, and a cover plate 14. The end plates 11 are provided on the outside of the batteries 20 located at both ends of the battery stack 2 in the stacking direction of the batteries 20. The side plates 12 cover the side surfaces of the battery stack 2, sandwiching the end plates 11 between them. The base plate 13 covers the bottom of the battery stack 2. The cover plate 14 covers the top surface of the battery stack 2.

[0012] The battery stack 2 is stored inside the housing 1. The battery stack 2 is composed of multiple batteries 20 stacked in one direction. Separators 3 made of a resin material or the like and shaped like a sheet or plate are provided between each battery. The separators 3 electrically insulate the batteries 20 in the battery stack 2. The separators 3 are built into and integrated with the battery stack 2, and so can be considered to form part of the battery stack 2.

[0013] Each battery 20 is a rechargeable secondary battery such as a lithium ion battery, a nickel-hydrogen battery, or a nickel-cadmium battery. Each battery 20 is a so-called prismatic battery, and has an outer can 21 in the shape of a flattened rectangular parallelepiped. A substantially rectangular opening (not shown) is provided on one side of the outer can 21, and an electrode assembly, an electrolyte, etc. are accommodated in the outer can 21 through this opening. A sealing plate 21a that closes the opening is provided at the opening of the outer can 21.

[0014] A positive output terminal 22 is disposed on the sealing plate 21a near one end in the longitudinal direction, and a negative output terminal 22 is disposed on the other end. The pair of output terminals 22 are electrically connected to the positive and negative electrode plates constituting the electrode body, respectively. 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. For convenience in the following description, the sealing plate 21a is referred to as the upper surface of the battery 20, and the bottom surface of the exterior can 21 facing the sealing plate 21a is referred to as the lower surface of the battery 20.

[0015] The battery 20 also has two main surfaces connecting the upper and lower surfaces. These main surfaces are the surfaces with the largest area among the six surfaces of the battery 20. The main surfaces are the long side surfaces connected to the long sides of the upper and lower surfaces. The two remaining surfaces excluding the upper and lower surfaces and the two main surfaces are the side surfaces of the battery 20. These side surfaces are a pair of short side surfaces connected to the short sides of the upper and lower surfaces. 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.

[0016] A valve portion 24 is provided on the sealing plate 21a between the pair of output terminals 22. The valve portion 24 is also called a safety valve, and is a mechanism for each battery 20 to release gas inside the battery. The valve portion 24 is configured to open when the internal pressure of the exterior can 21 rises to a predetermined value or higher, thereby allowing the internal gas to be released. The valve portion 24 is configured, for example, by a thin-walled portion that is provided in a part of the sealing plate 21a and is thinner than the other parts, and a linear groove formed on the surface of the thin-walled portion. In this configuration, when the internal pressure of the exterior can 21 rises, the thin-walled portion tears starting from the groove, thereby opening the valve.

[0017] The multiple batteries 20 are stacked at a predetermined interval so that the main surfaces of adjacent batteries 20 face each other. Note that "stacking" means arranging multiple members in any one direction. Therefore, stacking the batteries 20 also includes arranging the multiple batteries 20 horizontally. In this embodiment, the batteries 20 are stacked horizontally. The batteries 20 are arranged so that the output terminals 22 face the same direction. In this embodiment, the batteries 20 are arranged so that the output terminals 22 face vertically upward.

[0018] The end separators 4 are provided between the batteries 20 located at the ends of the battery stack 2 in the stacking direction of the batteries 20 and the end plates 11. Fig. 3 is a perspective view of the end separator 4 seen from the battery 20 side, and Fig. 4 is a cross-sectional side view of the end separator 4. Fig. 4 corresponds to a cross section including the stacking direction and the up-down direction of the batteries.

[0019] The end separator 4 comprises a substrate 40 that intersects with the stacking direction of the batteries 20, a deformation-permitting portion 41, and an air passage forming portion 42. The deformation-permitting portion 41 is a portion of the end separator 4 in the stacking direction of the batteries 20, and is made of a resin material that is more susceptible to creep deformation than other portions. The substrate 40 and the air passage forming portion 42 are made of a resin material that is less susceptible to creep deformation than the deformation-permitting portion 41.

[0020] The deformation allowing portion 41 is formed in a trapezoid shape rising in the stacking direction from the center of the surface of the substrate 40 facing the end plate 11, and the end face 41a contacts the end plate 11. The air passage forming portion 42 is composed of multiple strips protruding from the surface of the substrate 40 facing the battery 20, and air passages 43 are formed between each strip.

[0021] The end separator 4 contacts the end plate 11 at an end face 41a of the deformation-permitting portion 41, and contacts the battery 20 at an end face 42a of the air-path forming portion 42. The battery 20 is fitted into a wall portion 44 that is provided on the side of the substrate 40 and surrounds the substrate 40. The deformation-permitting portion 41 is subject to large creep deformation as described above, and is made of a material different from the substrate 40 and the air-path forming portion 42. The deformation-permitting portion 41 may be formed separately from the substrate 40 and fixed to the substrate 40 by adhesion or the like, or may be fixed to the substrate 40 by integral molding with the substrate 40 and the air-path forming portion 42.

[0022] Next, the operation of the battery module 100 will be described based on the generation of a reaction force due to the swelling of the batteries 20. Fig. 5 is a schematic diagram for explaining the positional relationship inside the battery module 100 at the initial stage. Fig. 5 corresponds to a cross section including the stacking direction and the up-down direction of the batteries. In the initial stage after manufacture, there is no swelling in each battery 20, and the reaction force acting on each battery 20 in the stacking direction is small and within the design tolerance.

[0023] Fig. 6 is a schematic diagram for explaining a state in which the batteries 20 in the battery module 100 have swelled in the stacking direction due to deterioration over time. Fig. 6 corresponds to a cross section including the stacking direction and the up-down direction of the battery. As described above, the internal electrodes and electrolyte deteriorate over time, and the batteries 20 swell and change in external shape due to deposition and oxidation of metal substances. Each battery 20 is a prismatic battery and has an exterior can 21 in the shape of a flattened rectangular parallelepiped, and of the six faces of the battery 20, the main surface with the largest area deforms to swell.

[0024] The deformation in the stacking direction caused by the expansion of each battery 20 in the battery module 100 is absorbed by the deformation-permitting portion 41 of the end separator 4 decreasing in dimension in the stacking direction due to creep deformation. Therefore, the battery module 100 can reduce the reaction force generated in the stacking direction.

[0025] The deformable portion 41 is provided so as to come into contact with the end plate 11, and can receive the load from the end plate 11 made of a highly rigid material such as metal evenly on the end face 41a which is the contact surface.

[0026] Furthermore, the deformable portion 41 does not need to contact the entire opposing surface of the end plate 11, but can be formed in a trapezoidal shape rising from the center of the surface of the substrate 40 facing the end plate 11 in the stacking direction, thereby reducing the contact area and increasing the generated stress.

[0027] The end separator 4 has an air passage forming portion 42 on the side that comes into contact with the battery 20, thereby making it possible to secure an air passage 43 for cooling the battery 20. The air passage forming portion 42 is made of a material that has smaller creep deformation than the deformation-permitting portion 41, thereby making it possible to suppress a reduction in the flow path area of ​​the air passage 43.

[0028] The deformation allowing portion 41 is formed integrally with the substrate 40 and the air passage forming portion 42 by a manufacturing method such as two-color molding, thereby making it possible to reduce manufacturing costs.

[0029] In the above embodiment, the deformable portion 41 is provided on the end plate 11 side, but the deformable portion 41 may be provided on the battery 20 side. Even in this configuration, the deformable portion 41 receives a load due to the expansion of the battery 20, and creep deformation occurs, thereby reducing the reaction force generated in the stacking direction in the battery module 100.

[0030] The above description is based on the embodiments of the present invention. These embodiments are merely examples, and it will be 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 that 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.

[0031] The embodiment may be specified by the following items. [Item 1] a battery stack (2) in which a plurality of batteries (20) are stacked; an end plate (11) provided on the outside of a battery (20) at an end in the stacking direction of the plurality of batteries (20); an end separator (4) provided between the end battery (20) and the end plate (11), the end separator (4) having a deformation allowance portion (41) formed in a portion in the stacking direction and in which deformation due to creep is larger than other portions; The battery module (100) comprises: a first insulating layer (14) and a second insulating layer (15) that electrically connects the first insulating layer (14) to the first insulating layer (15). [Item 2] The battery module (100) according to item 1, wherein the end separator (4) has the deformation-permitting portion (41) formed in a portion that contacts the end plate (11). This allows the deformation-permitting portion (41) of the battery module (100) to uniformly bear the load from the end plate (11) made of a highly rigid material such as metal on the contact surface. [Item 3] The battery module (100) according to item 1 or 2, wherein the deformable portion (41) is formed so as to rise in a trapezoidal shape from a surface intersecting the stacking direction, thereby reducing the contact area of ​​the deformable portion (41) with the end plate (11) and increasing the generated stress. [Item 4] The battery module (100) according to any one of items 1 to 3, wherein an air passage (43) is formed between the end battery (20) and the end separator (4). This allows the battery module (100) to ensure an air passage (43) for cooling the battery (20). [Item 5] The battery module (100) according to any one of items 1 to 4, wherein the end separator (4) is formed integrally with the deformation-permitting portion (41) and other portions, thereby enabling the battery module (100) to be manufactured at reduced cost. [Explanation of symbols]

[0032] 11 end plate, 2 battery stack, 20 battery, 4 end separator, 41 deformation allowance portion, 43 air passage, 100 battery module.

Claims

1. a battery stack formed by stacking a plurality of batteries; an end plate provided on the outside of the battery at an end in the stacking direction of the plurality of batteries; an end separator provided between the end battery and the end plate, the end separator having a deformation allowance portion formed in a portion in the stacking direction and having a larger deformation due to creep than other portions; Equipped with the end separator has a substrate intersecting the stacking direction and an air passage forming portion provided on the battery side of the end of the substrate, the deformable portion is formed separately from the substrate and then fixed to the substrate, the deformable portion is provided on the end plate side of the substrate so as to rise from the substrate in a trapezoidal shape and to be in contact with the end plate, The battery module, wherein the air passage forming portion forms an air passage between the battery at the end portion and the substrate.

2. The end separator has a wall portion provided on a side edge portion of the substrate and surrounding the substrate, 2. The battery module according to claim 1, wherein the end batteries are fitted into the wall portions.

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