JP7590201B2 - Elastic body for battery module - Google Patents

Description

The present invention relates to an elastic body for a battery module.

In secondary batteries, such as lithium-ion secondary batteries, the degree of expansion and contraction of battery cells accompanying charging and discharging has increased in recent years as the charge and discharge capacity has improved. In addition, secondary battery modules used in automobiles and the like are required to have high energy density (smaller batteries) in order to improve fuel efficiency. In such secondary battery modules, multiple battery cells are densely stacked, and as the battery cells expand during charging, adjacent battery cells may press against each other and damage the battery cells. For this reason, an elastic body is provided between the battery cells as a cushioning material. For example, Patent Document 1 describes a cushioning sheet (elastic body) for an electric module that has a plate-shaped base portion and an elastic convex portion with a predetermined inclination to elastically support the battery cells when the battery cells expand in a curved convex shape as they are charged, and to apply a reaction force to the battery cells when they contract as they are discharged.

JP 2020-004556 A

In order to absorb the large displacement of the battery cell caused by charging and discharging while providing an appropriate reaction force, it is necessary to design the base part (substrate part) of the elastic body used as a cushioning material to be thin and the height of the elastic protrusions (convex parts) of the elastic body to be high. However, if the thickness of the substrate part is thin, when the elastic body is pressurized (compressed) with the convex parts arranged near the outer periphery of the substrate part, the substrate part area between each convex part will be significantly distorted. Therefore, when the elastic body is repeatedly pressurized with the expansion and contraction of the battery cell, and the substrate part is repeatedly greatly deformed (distorted), cracks are likely to occur at the ends of the substrate part, and the elastic body may tear from these cracks.
Moreover, the above-mentioned elastic body is usually manufactured by integral molding using a mold, such as press molding, injection molding, etc. If the thickness of the base material is made thin, cracks are likely to occur in the base material during finishing processing, such as cutting the connecting parts of the elastic body in order to separate them into individual elastic bodies in the elastic body manufacturing process, and the yield rate decreases.

The present invention aims to provide an elastic body suitable as a cushioning material to be placed between battery cells of a secondary battery module or between a battery cell and a restraining member, which has excellent finishing workability after molding in the manufacturing process, can increase the yield, and is less likely to crack even when repeatedly pressurized (compressed in the thickness direction).

The present inventors have conducted extensive research in light of the above problems and have found that by providing a thick portion on the outer periphery of the base portion and then increasing the thickness in the order of the base portion, the thick portion, and the protruding portions, it is possible to significantly improve the finishing processability after molding in the manufacturing process, and further that the resulting elastic body is less likely to crack even when repeatedly compressed.
The present invention has been completed based on these findings.

That is, the above-mentioned object of the present invention has been achieved by the following means.
[1]
A substrate portion,
A plurality of protrusions protruding from both sides of the base portion;
A thick portion is disposed on an outer periphery of the base portion,
The elastic body for a battery module, wherein the thicknesses of the base portion, the convex portion, and the thick portion satisfy the following formula (1):

Thickness of base portion < thickness of thick portion < thickness of protrusion portion (Equation 1)
[2]
The elastic body for a battery module according to [1], further comprising an edge portion on an outer periphery of the thick portion, the edge portion having a thickness thinner than the thickness of the base portion.
[3]
The elastic body for a battery module according to [1] or [2], wherein the thicknesses of the base portion, the convex portion, and the thick portion satisfy the following (Formula 2) and (Formula 3):

Thickness of base material < 0.5 × thickness of thick portion (Equation 2)
Thickness of thick portion < 0.6 × thickness of protruding portion (Equation 3)
[4]
The elastic body for a battery module according to any one of [1] to [3], wherein the closest distance between the convex portion and the thick portion satisfies the following (Formula 4):

y>0.24x (y: closest distance, x: maximum diameter of convex portion) (Equation 4)

In this specification, the units of thickness for each part in (Equation 1) to (Equation 3) are the same. Also, the units of closest distance and maximum diameter of the convex part in (Equation 4) are the same.

The elastic body for battery modules of the present invention has excellent finishing workability after molding during the manufacturing process, which can increase the yield. Furthermore, even if the elastic body is repeatedly pressurized, it is unlikely to crack in the base material, and as a cushioning material for secondary battery modules, it can adequately elastically support the battery cells even after repeated charging and discharging over a long period of time, and can provide an appropriate reaction force to the battery cells.

1 is a perspective view showing one embodiment of an elastic body for a battery module of the present invention. 1 is a top view showing one embodiment of an elastic body for a battery module of the present invention. 1 is a side view showing one embodiment of an elastic body for a battery module of the present invention. 4A and 4B are explanatory views showing an example of a manufacturing process of the elastic body for a battery module of the present invention, in which FIG. 4A shows a state immediately after demolding, and FIG. 4B and FIG. 4C show a finishing process (a process of cutting the connecting portion). 5A and 5B are explanatory diagrams illustrating an embodiment of a battery module to which the elastic body for a battery module of the present invention is applied, in which Fig. 5A shows a battery module in a state in which the battery cells are not expanded, and Fig. 5B shows a battery module in a state in which the battery cells are fully expanded when fully charged.

The following describes an embodiment of the present invention with reference to the drawings as appropriate. However, the embodiment described below shows a preferred embodiment of the present invention, and the present invention is not limited to the following except as specified in the present invention.

(Elastic body for battery module of the present invention)
A preferred embodiment of the elastic body for a battery module of the present invention (hereinafter also referred to as the "elastic body of the present invention") is shown in Figures 1 to 3. The elastic body 1 of the present invention shown in Figures 1 to 3 includes a base portion 11, a plurality of convex portions 12 (first convex portion 12a, second convex portion 12b) arranged on both sides (first surface 11a and second surface 11b) of the base portion, and a thick portion 13 provided on the outer periphery of the base portion.
In the present invention, the relationships among the above-mentioned components are set to satisfy the following formula (1).

Thickness of base portion < thickness of thick portion < thickness of protrusion portion (Equation 1)

1 to 3, the elastic body of the present invention is also preferably configured to have an edge portion 14 on the outer periphery of the thick portion. In this case, the edge portion 14 is preferably formed to be thinner than the thickness of the base portion 11.

In the elastic body of the present invention, the base material, the protruding portion, and the thick portion may be integrally formed using the same material, or may be formed by joining the two using different materials, and it is preferable that they are integrally formed using the same material. When the same material is used, it is preferable that the base material, the protruding portion, and the thick portion are formed from an elastomer. When different materials are used, for example, the base material can be made of a metal plate material such as aluminum, iron, or stainless steel, and the protruding portion and the thick portion can be formed from an elastomer. Furthermore, the elastic body can be formed by two-color molding using different types of elastomers for the base material, the protruding portion, and the thick portion. It is preferable that the above-mentioned elastomer forms a crosslinked structure when the elastic body is constituted. This crosslinked structure can be formed using a crosslinking agent. As the crosslinking agent, an organic peroxide or the like that is normally used in vulcanization of elastomers can be appropriately used.

As the elastomer, for example, ethylene propylene diene rubber (EPDM), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (isobutylene-isoprene rubber) (IIR), etc. Among them, from the viewpoint of compression set (resistance to set), it is preferable that the elastomer is EPDM.
From the viewpoints of providing an appropriate reaction force and preventing cracks, as well as preventing cracks during the manufacturing process, the rubber hardness of the elastomer constituting the elastic body of the present invention is preferably 55 degrees or more, more preferably 60 degrees or more, and even more preferably 65 degrees or more, in terms of rubber hardness in accordance with JIS K6253: 2012. From the same viewpoint, the rubber hardness is preferably 82 degrees or less, more preferably 75 degrees or less, and even more preferably 70 degrees or less.
From the same viewpoint as above, the breaking elongation of the elastomer constituting the elastic body of the present invention is preferably 120% or more, more preferably 150% or more, and even more preferably 180% or more, in a tensile test at room temperature in accordance with JIS K6251: 2017. In this specification, "breaking elongation of 120%" means that the sample breaks when its length becomes 1.2 times that of the sample before the test.

The size of the elastic body of the present invention can be set appropriately taking into consideration the size of the applied electric module and the size of the battery cell. For example, in FIG. 2, the length in the first direction of the elastic body of the present invention (L': long side, length of the thick part 13) is preferably 100 to 500 mm, more preferably 200 to 400 mm, and even more preferably 250 to 350 mm. Similarly, the length in the second direction of the elastic body of the present invention (L": short side, length of the thick part 13) is preferably 50 to 200 mm, more preferably 75 to 150 mm, and even more preferably 80 to 110 mm. When the edge part 14 is provided, the thickness of the edge part 14 can be thinner than the thickness of the base part 11 as described above, and the size in the width direction can be adjusted appropriately according to the purpose.

The elastic body of the present invention is disposed between adjacent battery cells or between a battery cell and a restraining member. The elastic body of the present invention absorbs (elastically supports) the expansion and deformation that accompanies charging and discharging of the battery cell, and provides a sufficient reaction force when the battery cell contracts.
For example, when the elastic body of the present invention is compressed 15% in the thickness direction (in the present invention, the thickness direction is also referred to as the stacking direction assuming the state in which it is incorporated into a battery module; Figure 3) (compressed until the thickness is 85%), the surface pressure is preferably 0.2 MPa or more, and more preferably 0.25 MPa or more. Furthermore, when the elastic body of the present invention is compressed 40% in the thickness direction (compressed until the thickness is 60%), the surface pressure is preferably 1.5 MPa or less, and more preferably 1.2 MPa or less. Note that in the present invention, the surface pressure is calculated based on the total contact area between the surface of the battery cell and the multiple protrusions in the elastic body of the present invention.

Each part constituting the elastic body of the present invention will be described.
[Base material]
3, the substrate serving as the base of the elastic body of the present invention is plate-shaped and has a first surface 11a and a second surface 11b. The thickness (mm) (the distance from the first surface to the second surface) of the substrate constituting the elastic body of the present invention is preferably 0.1 to 2.0 mm, more preferably 0.3 to 1.5 mm, and even more preferably 0.5 to 0.8 mm, from the viewpoint of maintaining the strength of the elastic body.

When the elastic body of the present invention is integrally molded using an elastomer material, the base portion is compressed in the same manner as the protruding portion as the battery cell expands. For this reason, it is preferable that the thickness of the base portion is thinner than the thickness of the protruding portion and the thickness of the thick portion, from the viewpoint of ensuring a sufficient gap between the battery cell surface and the base portion. For example, it can be 0.18 times or less the thickness of the protruding portion, and it is even more preferable that the thickness is 0.15 times or less the thickness of the protruding portion.

[Convex part]
As shown in FIG. 3, the elastic body of the present invention has convex portions 12 (first convex portion 12a and second convex portion 12b) that protrude from both sides (first surface 11a and second surface 11b) of the base material in the thickness direction (stacking direction) of the base material.
In the present invention, the convex portions can appropriately provide elastic support against the expansion of the battery cell due to charging, and the pressure-receiving area (size) and the number of convex portions arranged can be appropriately set so as to apply a reaction force to the battery cell when the battery cell contracts due to discharging.

The shape of the protrusions of the elastic body of the present invention is not particularly limited and may be appropriately designed within a range that does not impair the effects of the present invention. For example, the shape of the protrusions may be a cylindrical shape, a truncated cone shape, a truncated quadrangular pyramid shape, or other polygonal truncated pyramid shapes. Among these, the shape of the protrusions is preferably a cylindrical shape.
The maximum diameter of the convex portion can also be appropriately set according to the desired pressure-receiving area and the number of convex portions arranged. In this specification, the "maximum diameter of the convex portion" refers to the maximum diameter (the longest length from one point on the periphery of the surface to another point on the periphery of the surface) on a surface perpendicular to the stacking direction and in contact with the battery cell, etc. For example, if the convex portion is circular when viewed from the stacking direction, it means the diameter of the convex portion, if the convex portion is rectangular, it means the length of the diagonal line, and if the convex portion is trapezoidal when viewed from the first direction or the second direction, it means the diameter at the top of the convex portion (the surface in contact with the battery cell).
For example, when the shape of the convex portion of the elastic body of the present invention is cylindrical, the maximum diameter (φ: diameter) of the convex portion is preferably 4 to 18 mm, more preferably 5 to 12 mm, and even more preferably 6 to 10 mm.

In the elastic body of the present invention, it is preferable that the multiple protrusions are arranged independently in a first direction (first arrangement direction) and also in a second direction (second arrangement direction). Figures 1 and 2 show an example in which multiple protrusions are arranged in the first and second directions that are perpendicular to each other. That is, four adjacent protrusions are arranged so as to be located at the vertices of a square. Alternatively, multiple protrusions may be arranged independently in a direction that has an angle with respect to the first and second directions instead of the first direction. That is, four adjacent protrusions may be arranged so as to be located at the vertices of a parallelogram. That is, the first and second directions may be directions that intersect with each other.

The distance (mm) between two adjacent protrusions in a plurality of independent protrusions that are closest to each other (e.g., the distance between two adjacent protrusions in the first direction) can be set appropriately taking into consideration the diameter (maximum diameter) of the protrusions and their occupancy rate relative to the area of the base material. For example, it is preferably 6 to 48 mm, more preferably 8 to 38 mm, and even more preferably 10 to 24 mm.

3, when the elastic body 1 of the present invention is assembled into a battery module, a gap (space) 16 is formed by the multiple protrusions 12 (12a) and the base material portion 11 (11a) between the surface 15a1 of the battery cell 15 and the elastic body 1 of the present invention. The presence of this space allows the expansion and deformation of the battery cell to be absorbed and provides appropriate elastic support.
Therefore, the thickness of the convex portion is preferably 1.5 to 7.0 mm, more preferably 2.0 to 6.0 mm, and even more preferably 3.5 to 5.0 mm. In this specification, the "thickness of the convex portion" means the distance (length) from the top of the first convex portion to the top of the second convex portion. In other words, in this specification, the "thickness of the convex portion" means the total height of the two convex portions (the first convex portion and the second convex portion) arranged on the first and second surfaces of the base portion, plus the thickness of the base portion on which the two convex portions are erected.

[Thick part]
In the elastic body of the present invention, the thick portion functions as a rib that suppresses crack propagation in the base material when the elastic body is repeatedly compressed. In addition, by having the thick portion in the elastic body of the present invention, it is possible to suppress poor cutting during demolding in the elastic body manufacturing process. The thick portion is formed on the outer periphery of the base material. However, the thick portion is not limited to the outer periphery, and may be provided in the center of the base material as appropriate, as long as it can provide appropriate elastic support and reaction force.

The shape of the thick portion is not particularly limited and can be appropriately set depending on the purpose. For example, when the elastic body of the present invention is cut in the lamination direction, it is preferable that the cross section is circular as shown in FIG.
In the elastic body of the present invention, the thickness of the thick portion is thicker than the thickness of the base portion and thinner than the thickness of the protruding portion. In this specification, the "thickness of the thick portion" means the thickness in the stacking direction. In order for the thick portion to fully function as a rib, the thickness of the thick portion is preferably more than twice the thickness of the base portion, and more preferably three times or more. In addition, since the thick portion may also be compressed when the battery cell expands, in order to fully absorb the deformation of the battery cell when it expands, the thickness of the thick portion is preferably less than 0.6 times the thickness of the protruding portion.
From the same viewpoint as above, the thickness of the thick portion is preferably 1.0 to 4.0 mm, and more preferably 1.8 to 2.1 mm.

The thick portion is preferably formed at a certain distance from the protruding portion located at the outermost periphery of the elastic body of the present invention. From the viewpoint of suppressing contact between the thick portion and the protruding portion compressed during expansion of the battery cell and of sufficiently absorbing deformation, it is preferable that the closest distance (mm) between the thick portion and the protruding portion is more than 0.24 times the maximum diameter (mm) of the protruding portion.
From the same viewpoint as above, the closest distance is preferably 1.92 to 5.00 mm.

[Edge]
When a plurality of elastic bodies of the present invention are integrally molded, a part of the connecting portion may be provided as an edge portion (flat portion). By providing an edge portion, stress when the connecting portion is cut in the finishing process can be concentrated on the edge portion, and the occurrence of cracks in the base portion can be significantly suppressed. Even when the elastic body of the present invention is integrally molded using a single-cavity mold, it is also preferable to provide an edge portion on the outer periphery of the thick portion in the same manner from the viewpoint of preventing the occurrence of cracks in the base portion when removing the overflow portion that has leaked out to the outer periphery. As shown in FIG. 4(a), in the present invention, the edge portion 14 refers to the portion of the connecting portion 17 that contacts the thick portion and its vicinity. The thickness of the edge portion is preferably thinner than the thickness of the base portion, and is preferably 1/3 times or less the thickness of the thick portion. The thickness of the edge portion is usually 0.02 to 0.40 mm. When the elastic body of the present invention has an edge portion, the edge portion does not substantially affect the function of the elastic body of the present invention.

(Manufacturing of elastic bodies)

A preferred example of the method for producing the elastic body of the present invention is described below, but the method for producing the elastic body of the present invention is not limited to the method described below as long as the elastic body of the present invention can be obtained.

[Molding process]
In the molding step, the elastic body of the present invention can be obtained, for example, by molding an elastomer material using a mold press and vulcanizing the molded product.
The die press molding may be any method that is commonly used for producing an elastic body. In the present invention, die press molding broadly includes methods of molding using a die, such as compression molding, transfer molding, and injection molding.

FIG. 4(a) shows a schematic diagram of an example of compression molding immediately after demolding. FIG. 4(a) shows a form in which two elastic bodies of the same shape are obtained simultaneously by one set of dies. That is, this is a manufacturing method using a two-cavity die 2. The number of dies can be appropriately designed according to the purpose. In this compression molding, an elastomer material preformed in a predetermined shape is set in a die heated to a predetermined temperature together with a crosslinking agent as necessary. At this time, the elastomer material is usually charged in the die in an amount greater than the weight of the desired elastic body. By charging an elastomer material in an amount greater than the weight of the desired elastic body, an elastic body of the desired shape can be obtained without chipping on the outer periphery of the molded product.
The elastomer material charged in the mold is formed into the elastic body 1 and the edge portion 14 and the connecting portion 17 according to the shape of the mold by clamping the upper and lower molds and applying heat and pressure to the elastomer material for a certain period of time.
In the above molding and crosslinking reaction step, the mold temperature is preferably 150 to 200° C. and the reaction time is preferably 2 to 10 minutes.

[Finishing process]
In FIG. 4(b), the elastic body of the present invention is taken out including the connecting portion 17, and in the finishing process, the connecting portion is cut off to obtain two elastic bodies (FIG. 4(c)).

When the elastic body is composed of only the base material and the protrusions, and does not have thick parts, the difference in thickness between the connecting parts (or edges) and the base material is small, and it is difficult for sufficient stress concentration to occur at the boundary between the connecting parts (or edges) and the base material. As a result, the cutting of the connecting parts in the finishing process tends to cause cracks in the base material. These cracks may even extend to the center of the base material.
In contrast, by providing a thick portion as defined in the present invention on the outer periphery of the base material portion, the difference in thickness between the connecting portion (or edge portion) and the thick portion can be increased. As a result, stress is concentrated at the boundary between the connecting portion (or edge portion) and the thick portion, and the occurrence of defective products in the finishing process can be significantly reduced.

The cutting of the connecting parts in the finishing process may be done manually or with a jig or device. By having a thick part on the outer periphery of the base part, the occurrence of cracks in the base part due to the cutting of the connecting parts in the finishing process can be significantly reduced, thereby improving productivity.

(Battery module configuration)
A battery module to which the elastic body of the present invention is applied will be described with reference to Figures 5(a) and (b). Figure 5(a) is an explanatory diagram showing a battery module having discharged battery cells, and Figure 5(b) is an explanatory diagram showing a battery module having battery cells expanded by charging, in a state where the arrangement of the internal battery cells and elastic bodies can be seen. In this explanatory diagram, the state of the internal electrode body of one of the five battery cells is also shown.

The battery module 3 comprises a plurality of battery cells 15, a restraining member 31, and an elastic body 1 of the present invention arranged between the battery cells or between the battery cells and the restraining member. In the battery module 3, the battery cells 15 and the elastic bodies 1 are alternately stacked and held by the restraining members 31 (31a, 31b, 31c). The battery cells 15 comprise a housing 15a and an electrode body 15b inside the housing 15a. The battery cells 15 are secondary batteries capable of charging and discharging power, and for example, lithium ion secondary batteries or the like can be suitably used.

When a battery cell 15 is charged, the internal electrode body (negative electrode) absorbs ions and expands, causing the battery cell as a whole to expand (Fig. 5(b)). The amount of expansion is greatest when the battery cell is fully charged. A charged battery cell shrinks when discharged, and ideally returns to the flat shape shown in Fig. 5(a). When this expansion and contraction of the electrode body is repeated, the distance between the electrodes inside the battery cell gradually increases, and battery performance deteriorates over time.

The restraining members 31 restrain the battery module 3 from both ends in the stacking direction. That is, when each battery cell expands due to charging, the restraining members absorb the expansion and apply a reaction force to each battery cell. This acts to return the battery cell to its initial state (unexpanded state). Even when the battery cell contracts due to discharging, the restraining members continue to apply a reaction force to the battery cell, thereby suppressing the expansion of the inter-electrode distance in the battery cell over time.
The restraining member 31 (31a) is preferably made of metal in order to exert a sufficient restraining force, but hard resin may also be used.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

(Production method)
[Example 1]
EPDM (product name: Esprene EPDM, manufactured by Sumitomo Chemical Co., Ltd.) was used as an elastomer material, and carbon black (model number: Asahi #60HN, manufactured by Asahi Carbon Co., Ltd.) was used as a filler, and then an organic peroxide-based curing agent (product name: Perhexa 25B, manufactured by NOF Corp.) was mixed as a crosslinking agent (vulcanizing agent), and the mixture was preformed into a rectangular shape using a mixing roll machine (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) and a super cutter (manufactured by Ogino Seiki Seisakusho Co., Ltd.). The preform was placed in a mold, and the mold was clamped and pressed at a temperature of 190°C for 4 minutes, thereby allowing a crosslinking reaction (curing reaction) to occur while molding. This mold is capable of obtaining two elastomers in one shot, as shown in Figure 4(a).
The obtained elastic body had a rubber hardness of 67 degrees (based on JIS K6253:2012) and a breaking elongation of 200% (based on JIS K6251:2017) in Durometer Type A. Here, "breaking elongation of 200%" means that the sample breaks when its length is doubled from the length before the test.
The elastic body of Example 1 has 157 convex portions on each of the first and second surfaces. That is, the elastic body has 157 convex portions 12, each of which is made up of a first convex portion 12a and a second convex portion 12b. The measurement results of the dimensions of each portion are shown in Table 1.

[Comparative Example 1]
The elastic body of Comparative Example 1 was produced in the same manner as in Example 1, except that the elastic body did not have a thick portion. The dimensions of each portion of the elastic body of Comparative Example 1 are shown in Table 1.

(Evaluation of workability in manufacturing the elastic body of the present invention)
[Finishing cut]
400 pieces of each of the elastic bodies of Example 1 and Comparative Example 1 were produced, and the number of defective products (elastic bodies with cracks in the substrate portion) in the manual finishing process by the same worker was counted. The results are shown in Table 1.

With the elastic body of Comparative Example 1, 63 defective products were generated during the finishing process. In contrast, with the elastic body of Example 1, which satisfies the configuration of the present invention, the generation of defective products during the finishing process was significantly reduced (finishing workability was significantly improved).

(Functionality test of elastic body)
The elastic bodies of Example 1 and Comparative Example 1 after the finishing process obtained above (non-defective: elastic bodies with no cracks generated in the finishing process) were used to measure the mechanical properties of the elastic bodies by the following tests.

[Load characteristics]
Using a compression tester (Universal Material Testing Machine, Model: 5585H (Instron)), pressure was applied to the elastic body under conditions of a load control range of 200 N to 60 kN and a test speed of 1 mm/min, and the surface pressure (MPa) was measured when the elastic body had a compression rate (%) of 15% and 40%. The measurement was performed three times for each elastic body, the average value was calculated, and a judgment was made according to the following evaluation criteria. Load characteristics rated as "good" are preferable as they can fulfill the intended function as a cushioning material for battery modules. The results are shown in Table 2.

-Evaluation criteria-
"Good": The surface pressure at a compression rate of 15% is 0.2 MPa or more, and the surface pressure at a compression rate of 40% is 1.5 MPa or less. "Poor": The surface pressure at a compression rate of 15% is less than 0.2 MPa, and/or the surface pressure at a compression rate of 40% is more than 1.5 MPa.

[Repetitive fatigue]
Using a compression tester (Universal material testing machine, model number: 5585H (manufactured by Instron)), the elastic body was repeatedly compressed 40,000 times under the conditions of load control range: 200N to 60kN, test speed: 5mm/min, and the presence or absence of cracks in the base material of the elastic body was examined and evaluated according to the following evaluation criteria. The results are shown in Table 2.

-Evaluation criteria-
"Good": No cracks were generated.
"Crack": A crack has occurred.

In the elastic body of Comparative Example 1, which does not have a thick portion, cracks occurred in the elastic body due to repeated compression. In contrast, in the elastic body of Example 1, which has a thick portion and satisfies the configuration of the present invention, no cracks occurred in the elastic body even after repeated compression 40,000 times.

From the above, it was found that an elastic body consisting of a base portion, a convex portion, and a thick portion and satisfying the configuration of the present invention has excellent workability (good yield) in the finishing process during manufacturing, and furthermore, the obtained elastic body has excellent resistance to repeated fatigue.

REFERENCE SIGNS LIST 1 Elastic body 11 Base material portion 11a First surface 11b Second surface 12 Convex portion 12a First convex portion 12b Second convex portion 13 Thick portion 14 Edge portion 15 Battery cell 15a Housing 15a1 Target surface 15b Electrode body 16 Gap (space)
17 Connection portion 2 Mold 3 Battery module 31 Restraint member 31a First restraint member 31b Second restraint member 31c Connection member L' Long side L'' Short side

Claims (4)

A substrate portion,
A plurality of protrusions protruding from both sides of the base portion;
A thick portion is disposed on an outer periphery of the base portion,
the base portion, the convex portion, and the thick portion are formed from the same elastomer,
The elastic body for a battery module, wherein the thicknesses of the base portion, the convex portion, and the thick portion satisfy the following formula (1):

Thickness of base portion < thickness of thick portion < thickness of protrusion portion (Equation 1)
A substrate portion,
A plurality of protrusions protruding from both sides of the base portion;
A thick portion disposed on an outer periphery of the base portion;
and an edge portion disposed on an outer periphery of the thick portion,
The thicknesses of the base portion, the convex portion, and the thick portion satisfy the following formula (1),
The elastic body for a battery module, wherein the edge portion has a thickness smaller than a thickness of the base portion.

Thickness of base portion < thickness of thick portion < thickness of protrusion portion (Equation 1)
A substrate portion,
A plurality of protrusions protruding from both sides of the base portion;
A thick portion is disposed on an outer periphery of the base portion,
The elastic body for a battery module, wherein the thicknesses of the base portion, the convex portion, and the thick portion satisfy the following (Formula 1) to (Formula 3).

Thickness of base portion < thickness of thick portion < thickness of protrusion portion (Equation 1)
Base material thickness < 0.5 x thickness of thick part ... (Equation 2)
Thickness of thick part < 0.6 x thickness of protruding part ... (Equation 3)
A substrate portion,
A plurality of protrusions protruding from both sides of the base portion;
A thick portion is disposed on an outer periphery of the base portion,
The thicknesses of the base portion, the convex portion, and the thick portion satisfy the following formula (1),
The elastic body for a battery module, wherein the closest distance between the convex portion and the thick portion satisfies the following (Formula 4):

Thickness of base portion < thickness of thick portion < thickness of protrusion portion (Equation 1)
y>0.24x (y: closest distance, x: maximum diameter of convex portion) (Equation 4)

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