Battery cushioning material

Abstract

To provide a cushioning material for batteries capable of suppressing increase in reaction force in a predetermined range of compression amount.SOLUTION: A cushioning material 100 for batteries has an upper side part 11, a lower side part 13, and a plurality of coupling parts 10 connecting between the upper side part 11 and the lower side part 13. The coupling parts 10 are made of an elastic material, and when added with an external force equal to or more than a predetermined external force to make the upper side part 11 and the lower side part 13 approach each other, are deformed to suppress increase in reaction force.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a cushioning material for batteries, and more particularly to a cushioning material for batteries such as secondary batteries used in electric vehicles and the like. [Background technology]

[0002] Batteries (secondary batteries) have been widely used as energy sources for electric vehicles, etc. These batteries include multiple battery cells and cushioning materials (battery cushioning materials), and a known battery cell configuration includes an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked, and this electrode assembly is housed in a storage case.

[0003] This battery is provided with a restraining portion that restrains a plurality of storage cases, each containing an electrode assembly, in the stacking direction. The restraining portion is disposed on the outside of the storage cases and restrains the storage cases from the outside.

[0004] Such a battery expands and contracts due to heat generated during charging and discharging while the multiple storage cases are restrained by the restraining portion.

[0005] The electrodes are subjected to a load due to expansion caused by this charge and discharge, and cushioning materials (battery cushioning materials) are used to prevent the electrodes from being damaged by this load (see, for example, Patent Document 1). Furthermore, cushioning materials are effectively used not only to reduce the expansion caused by the above-mentioned charge and discharge, but also to reduce impact when the battery is vibrated, for example. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-4556 Summary of the Invention [Problem to be solved by the invention]

[0007] However, cushioning materials such as the buffer sheet of Patent Document 1 still have room for further improvement. Specifically, cushioning materials such as the buffer sheet of Patent Document 1 generate a large reaction force as the amount of compression due to an external force such as a load increases, and in particular, once a certain amount of compression is exceeded, a large reaction force tends to occur suddenly (see FIG. 13). When a large reaction force (especially a sudden large reaction force) occurs, a large force tends to be applied to the cushioned object (for example, the storage case for a battery). Therefore, even if a large external force is applied and the amount of compression increases, conventional cushioning materials still have room for improvement in that the increase in reaction force is suppressed and a large reaction force is less likely to occur.

[0008] The present invention was made in consideration of such conventional technology, and its objective is to develop a cushioning material for batteries that suppresses an increase in reaction force within a specified range of compression. [Means for solving the problem]

[0009] According to the present invention, there is provided the following cushioning material for a battery.

[0010] [1] A device having an upper side portion, a lower side portion, and a plurality of connecting portions connecting the upper side portion and the lower side portion, the connecting portion is made of an elastic material, the connecting portion has one surface at its base portion that is curved and the other surface that is flat, or one surface and the other surface at the base portion that are curved and have different radii of curvature; When an external force of a predetermined magnitude or greater is applied so that the upper edge portion and the lower edge portion approach each other, the connecting portion buckles, thereby suppressing an increase in the reaction force.

[0012] [ 2 When one surface of the base of the connecting portion is curved and the other surface is flat, the flat surface is located on the outer side, When the curved surfaces have different radii of curvature, the outer surface has a smaller radius of curvature. 1] A cushioning material for batteries as described in the above.

[0013] [ 3 The connecting portion is formed from a pair of connecting bodies. or [2] The cushioning material for a battery according to claim 1.

[0014] [ 4 ] The connecting portion has a rib attached to the center thereof. 3 ] A cushioning material for a battery described in any one of the following. [5] A device having an upper side portion, a lower side portion, and a plurality of connecting portions connecting the upper side portion and the lower side portion, the connecting portion is made of an elastic material, The connecting portion has a rib attached to the center thereof, When an external force of a predetermined magnitude or greater is applied so that the upper edge portion and the lower edge portion approach each other, the connecting portion buckles, thereby suppressing an increase in the reaction force. [Effects of the Invention]

[0015] When an external force greater than a predetermined value is applied to the battery cushioning material of the present invention so that the upper and lower edges are brought closer together, the connecting portion made of an elastic material buckles, thereby maintaining the reaction force within a predetermined range of compression and suppressing an increase in the reaction force. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view schematically showing a state in which one embodiment of the cushioning material for a battery of the present invention is used. [Figure 2] FIG. 3 is a cross-sectional view schematically showing another state of use of the embodiment of the cushioning material for a battery of the present invention. [Figure 3] 1 is a perspective view schematically illustrating one embodiment of a cushioning material for a battery of the present invention. [Figure 4] 1 is a partial plan view schematically illustrating a part of one embodiment of a cushioning material for a battery of the present invention. [Figure 5] 5 is an explanatory view showing a state in which an external force is applied to the battery cushioning material shown in FIG. 4. FIG. [Figure 6] FIG. 10 is a partial plan view schematically illustrating a part of another embodiment of the cushioning material for a battery of the present invention. [Figure 7]FIG. 10 is a partial plan view schematically showing a part of still another embodiment of the cushioning material for a battery of the present invention. [Figure 8] FIG. 10 is a partial plan view schematically showing a part of still another embodiment of the cushioning material for a battery of the present invention. [Figure 9] FIG. 10 is a partial plan view schematically showing a part of still another embodiment of the cushioning material for a battery of the present invention. [Figure 10] 10 is an explanatory view showing a state in which the battery cushioning material shown in FIG. 9 is subjected to an external force. FIG. [Figure 11] 10 is a graph showing the relationship between the amount of compression and the reaction force in analysis result 1. [Figure 12] 10 is a graph showing the relationship between the compression amount and the reaction force in analysis result 2. [Figure 13] 10 is a graph showing the relationship between the amount of compression and the reaction force in Reference Example 1. [Figure 14] FIG. 1 is a perspective view schematically illustrating a conventional cushioning material for a battery. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and that appropriate design changes and improvements may be made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0018] (1) Battery cushioning material: One embodiment of the battery cushioning material of the present invention is a battery cushioning material 100 shown in Figures 3 and 4. The battery cushioning material 100 has an upper edge portion 11, a lower edge portion 13, and a plurality of connecting portions 10 connecting the upper edge portion 11 and the lower edge portion 13, and the connecting portions 10 are made of an elastic material. When an external force of a predetermined level or greater is applied to the battery cushioning material 100 so as to bring the upper edge portion 11 and the lower edge portion 13 closer to each other, the connecting portions 10 buckle, thereby suppressing an increase in the reaction force.

[0019] When such battery cushioning material 100 receives an external force that moves the upper edge portion 11 and the lower edge portion 13 closer to each other, it elastically deforms to absorb the external force. When an external force of a predetermined magnitude or greater is applied, the connecting portion 10 made of an elastic material buckles (see FIG. 5), thereby maintaining the reaction force within a predetermined range of compression and suppressing an increase in the reaction force. In other words, when a predetermined compression amount is reached, the connecting portion 10 buckles to suppress an increase in the reaction force.

[0020] The battery cushioning material 100 can be used as a cushioning material disposed between adjacent battery cells 210 among a plurality of battery cells 210, for example, as shown in FIG.

[0021] Here, rubber, which is the main material of the cushioning material, tends to be easily deformed when compressed in a region where the strain is small (when the compression amount is small), and therefore tends not to generate sufficient reaction force, as shown in Figure 13. On the other hand, in a region where the strain is large (when the compression amount is large), the more the rubber is distorted, the more the volume is compressed, and the reaction force tends to increase rapidly (see Figure 13). As such, conventional cushioning rubber products, which use rubber as the main material, have not been able to generate the desired sufficient reaction force while maintaining that reaction force constant over a wide compression range (in other words, suppressing the increase in reaction force).

[0022] The battery cushioning material of the present invention generates a desired sufficient reaction force while maintaining the reaction force constant over a wide compression range (in other words, suppressing an increase in the reaction force). That is, as shown in Fig. 12, for example, when a predetermined compression amount is reached, i.e., when a predetermined load is applied, the connecting portion 10 buckles to suppress an increase in the load. Even after buckling, the connecting portion 10 continues to function as a spring, thereby reducing a sudden decrease in the reaction force after buckling (see Fig. 12, for example).

[0023] There are no particular limitations on the shape of the battery cushioning material 100, but it is preferable that it be flat, and the thickness can be set appropriately taking into consideration the space in which the battery cushioning material 100 is to be placed, etc.

[0024] The size of the battery cushioning material 100 is not particularly limited and can be set as appropriate. When it is adjacent to the battery cell 210, it can be the same size as the battery cell 210 or slightly smaller than the battery cell 210.

[0025] (1-1) Connection part: The connecting portions 10 are made of an elastic material and connect the upper edge portion 11 and the lower edge portion 13. A plurality of connecting portions 10 are formed. When an external force of a predetermined magnitude or greater is applied to the connecting portions 10 so as to bring the upper edge portion 11 and the lower edge portion 13 closer to each other, the connecting portions 10 buckle, suppressing an increase in the reaction force (see, for example, FIG. 11 ). In other words, when the battery cushioning material 100 is subjected to an external force (an external force in a direction that brings the upper edge portion 11 and the lower edge portion 13 closer to each other), the connecting portions 10 deform so as to be crushed, and a reaction force against the external force is generated mainly by the connecting portions 10. When the external force further increases and exceeds a certain level, the connecting portions 10 buckle. This buckling prevents an increase in the reaction force, i.e., maintains the reaction force at a predetermined level (i.e., the degree of increase in the generated reaction force is gradual even when the amount of compression increases, and the plateau (flat) region of the reaction force becomes wider). The external force equal to or greater than a predetermined value refers to an external force equal to or greater than a predetermined value that is set in advance, and the range of load that will be applied to the buffer material due to the thermal expansion of the battery 200 can be estimated in advance, and the timing at which the connecting part 10 should buckle can be set in advance. Furthermore, external impact forces on the battery 200 can also be estimated and set in advance.

[0026] The shape of the connecting portion 10 is not particularly limited, but it may be columnar, wall-shaped, or the like.

[0027] The connecting portion 10 may be a continuous wall-like member extending from one end of the battery cushioning material 100 to the other end, or may be discontinuous (a column-like or wall-like member arranged at intervals).

[0028] "Buckling" refers to deformation such as bending.

[0029] There is no particular limit to the number of connecting portions 10 as long as a plurality of connecting portions 10 are formed, and the number can be set appropriately taking into consideration the magnitude of the reaction force maintained after buckling, etc.

[0030] The connecting portion 10 is preferably formed integrally with the upper side portion 11 and the lower side portion 13, but may also be provided as a separate body and joined to the upper side portion 11 and the lower side portion 13.

[0031] The thickness of the connecting portion 10 can be, for example, about 0.5 to 10 mm.

[0032] The thickness of connecting portion 10 may or may not be constant, as long as connecting portion 10 buckles and suppresses an increase in the reaction force when an external force of a predetermined magnitude or greater is applied so that upper side portion 11 and lower side portion 13 approach each other. If the thickness is not constant, the thickness may protrude so that the center is thicker than the other portions, as shown in Figure 4 (i.e., a rib 15 may be provided in the center).

[0033] The rib 15 may be provided on one surface of the connecting portion 10 or on both surfaces.

[0034] Fig. 1 shows a battery cushioning material 100 having connecting portions 10 with non-uniform thickness, with a rib 15 attached to the center. In other words, this shows an example in which a protrusion is formed so that the center of the connecting portion 10 is thicker than the other portions. By attaching a rib 15 to the center in this way, a strong spring effect is exerted after buckling, which can further suppress the decrease in surface pressure and further flatten the fluctuations in reaction force, thereby making the plateau (flat) region wider (see Fig. 11).

[0035] Fig. 6 shows a battery cushioning material 101 having a connecting portion 10 with a constant thickness, and when the connecting portion 10 has a constant thickness, the generated strain and stress are reduced, improving resistance to cracking, etc. In the battery cushioning material 102 shown in Fig. 6, one surface 20a of the base portion 20 is flat and the other surface 20b is curved.

[0036] It is preferable that the thickness of the base portion of the connecting portion is non-uniform. Specifically, it is preferable that one surface of the base portion of the connecting portion is curved and the other surface is flat, or that one surface and the other surface of the base portion are curved and the radii of curvature of these curved surfaces are different from each other. When one surface of the base portion of the connecting portion is curved and the other surface is flat, it is preferable that this flat surface (with a radius of curvature of 0) is located on the outer side. Furthermore, when the curved surfaces have different radii of curvature, it is preferable that the surface located on the outer side has a smaller radius of curvature. There is no particular limitation on the magnitude of the radius of curvature of the curved surfaces and it can be set appropriately.

[0037] In this way, when an external force of a predetermined magnitude or greater is applied so that the upper edge portion 11 and the lower edge portion 13 approach each other, the connecting portion 10 buckles more reliably, and furthermore, the direction in which the connecting portion 10 buckles can be controlled, preventing contact between adjacent connecting portions 10. Here, the reason why the buckling direction of the connecting portion can be controlled is that by making the internal stress uneven on the left and right sides (one surface side and the other surface side) (i.e., the side with the larger radius of curvature has higher internal stress), buckling in the direction of smaller stress becomes more likely.

[0038] 6, the connecting portion 10 can have a curved surface 20b at its base 20, which is located toward the center of the battery cushioning (i.e., toward the center in the direction perpendicular to the thickness direction of the battery cushioning), and a flat surface 20a opposite to the surface 20b (with a radius of curvature of 0). In this case, the connecting portion 10 buckles toward the surface 20a (flat surface), which is the direction in which stress is smaller.

[0039] 7, both surfaces 20a and 20b of the base portion 20 are curved surfaces A and B, respectively, and the radii of curvature of these curved surfaces A and B are different from each other, so that the outer surface 20a (curved surface B) has a smaller radius of curvature. In this case, the connecting portion 10 buckles toward the surface 20a (curved surface B), which is the direction in which the stress is smaller.

[0040] The connecting portion 10 may have a thickness that decreases from the center toward the ends (i.e., toward the upper edge 11 and the lower edge 13) in the thickness direction of the battery cushioning material 100, and the thickness may be asymmetric. In this case, the thinner portion (i.e., the portion with the greater thickness reduction) is more likely to buckle, making it possible to control the buckling direction of the connecting portion 10. This is because internal stress is uneven between the left and right sides (one surface side and the other surface side). Note that "asymmetric thickness" means that the difference between the lengths D1 and D2 of the following perpendicular lines is not zero. That is, when the battery cushioning material is viewed from the side (see, for example, FIG. 8), a center line L is drawn that passes through the center O of the connecting portion 10 and is parallel to the thickness direction of the battery cushioning material. Then, perpendicular lines are drawn from both the one surface 20a and the other surface 20b to the center line L, and the lengths of these perpendicular lines are defined as "perpendicular lengths D1 and D2." If the difference between the lengths D1 and D2 of the perpendicular lines extending from the foot of the same perpendicular line to both surfaces 20a and 20b is not 0, it is said that the thickness is asymmetric. In other words, if the difference between the lengths D1 and D2 of the perpendicular lines is 0, it can be said that the connecting portion 10 is uniformly (i.e., symmetrically) thin.

[0041] The connecting portion 10 can be formed from a pair of connecting bodies 30, 30, like the battery cushioning material 102 shown in Fig. 9. Each of the pair of connecting bodies 30, 30 is provided with a rib 15. Fig. 9 shows the battery cushioning material 102 in a state where no external force is being applied.

[0042] Figure 10 shows a state in which the connecting portion 10 of a battery cushioning material 102, which has a connecting portion 10 formed from a pair of connecting bodies 30, 30, is buckled. In Figure 10, an external force of a predetermined magnitude or greater is being applied so that the upper side portion 11 and the lower side portion 13 approach each other. The pair of connecting bodies 30, 30 are buckled in different directions (buckled away from each other) so as not to collide with each other.

[0043] The pair of connecting bodies 30, 30 may be in contact with each other or may be arranged with a gap therebetween.

[0044] The position where the connecting portion 10 is formed is not particularly limited and can be set appropriately.

[0045] The material of the connecting portion 10 can be appropriately selected from conventionally known rubber materials, and specific examples include ethylene propylene diene rubber (EPDM) and acrylic rubber (ACM).

[0046] The hardness of the connecting portion 10 is not particularly limited, but the value measured by JIS K 6253 durometer type A can be 10 to 90 degrees, and preferably 40 to 90. By setting the hardness in this range, when an external force of a predetermined magnitude or more is applied so that the upper side portion 11 and the lower side portion 13 approach each other, the connecting portion 10 buckles, and an increase in the reaction force is effectively suppressed.

[0047] (1-2) Top: The upper edge portion 11 is a plate-shaped portion that comes into contact with one of the members that applies an external force to the battery cushioning material 100. For example, as shown in FIG. 1 , when the battery cushioning material 100 is placed between two battery cells 210, the upper edge portion 11 comes into contact with one of the battery cells 210.

[0048] This upper side portion 11 may be flat, curved, or wavy, etc. The thickness of the upper side portion 11 is not particularly limited and can be set appropriately, for example, about 0.3 to 5 mm.

[0049] The material of the upper side portion 11 is not particularly limited, but examples thereof include rubber and resin. It is preferable to use the same rubber material as the connecting portion 10, and the upper side portion 11 can be formed integrally with the connecting portion 10.

[0050] (1-3) Bottom: The lower side 13 is a plate-shaped portion that comes into contact with the other member that applies an external force to the battery cushioning material 100. For example, as shown in Fig. 1, when the battery cushioning material 100 is placed between two battery cells 210, the lower side 13 is the portion that comes into contact with the other battery cell 210 (the side opposite to the upper side 11).

[0051] This lower side portion 13 may be flat, curved, wavy, etc. The thickness of the lower side portion 13 is not particularly limited and can be set appropriately, for example, about 0.3 to 5 mm.

[0052] The material of the lower side portion 13 is not particularly limited, but examples thereof include rubber and resin. It is preferable to use the same rubber material as the connecting portion 10, and the lower side portion 13 can be formed integrally with the connecting portion 10.

[0053] (2) Use of the battery cushioning material of the present invention: The battery cushioning material 100 can be disposed between adjacent battery cells 210, as in the battery 200 shown in FIG. 1, or between a stack of multiple battery cells 210 and a restraining portion 230, as in the battery 201 shown in FIG. 2. It is noted that not only one but multiple battery cushioning materials 100 can be used. In this case, multiple battery cushioning materials 100 may be used by stacking them, or multiple battery cushioning materials 100 may be used by arranging multiple materials on a plane, or these may be combined. The battery is not limited to an all-solid-state battery, and may also be a liquid electrolyte battery.

[0054] This arrangement absorbs the expansion force that occurs when the battery cell (battery) expands, and functions as a buffer when the battery is subjected to an external impact. Furthermore, it can absorb and correct pressure imbalances caused by variations (placement errors) when stacking components such as the battery cells 210.

[0055] Specifically, when the battery 200 thermally expands, the battery cushioning material 100 deforms so that the upper edge portion 11 and the lower edge portion 13 approach each other, absorbing the external force. At this time, a reaction force is generated from the battery cushioning material 100, maintaining a balance with the external force. Thereafter, when the external force exceeds a predetermined value, that is, when the amount of compression reaches a predetermined value, the connecting portion 10 buckles. Then, the buckled connecting portion 10 generates a reaction force like a spring, and the reaction force is suppressed from increasing even if the amount of compression increases until the predetermined amount of compression is reached. [Example]

[0056] (Analysis result 1) Assuming a flat battery cushioning material as shown in Figure 3, a simulation was conducted to analyze the amount of compression (mm) and reaction force (N). The material used for analysis was EPDM rubber (hardness A90), and the top and bottom surfaces were compressed under rigid wall bonding conditions to generate a reaction force, and the simulation was performed. The analysis results are shown in Figure 11.

[0057] As shown in Fig. 11, in the flat battery cushioning material shown in Fig. 3, the reaction force increases as the amount of compression increases, but once a certain amount of compression is reached, the increase in reaction force is suppressed. In other words, it is clear that the increase in reaction force is suppressed within a certain range of the amount of compression.

[0058] (Analysis result 2) A simulation analysis was performed on the compression amount (mm) and reaction force (N) assuming a flat battery cushioning material as shown in Fig. 6. The analysis material and analysis conditions were the same as those in Analysis Result 1. The analysis results are shown in Fig. 12.

[0059] As shown in Figure 12, for the flat battery cushioning material shown in Figure 6, a temporary fluctuation in reaction force was observed when the connecting part buckled. However, other than this, as in Analysis Result 1, it can be seen that the increase in reaction force is suppressed within a specified range of compression.

[0060] (Reference example 1) Fig. 13 shows the relationship between the amount of compression (mm) and the reaction force (N) in a conventional battery cushioning material such as the battery cushioning material 300 shown in Fig. 14. As shown in Fig. 13, as the amount of compression of the battery cushioning material increases, the increase in reaction force becomes much larger compared to the increase in the amount of compression.

[0061] As can be seen from the above-mentioned Analysis Results 1 and 2 and Reference Example 1, the battery cushioning material of the present invention suppresses an increase in reaction force even when subjected to a large external force, as long as the compression amount is within a predetermined range. Therefore, even if the battery thermally expands or the cushioning material is significantly compressed due to an external impact, the increase in the reaction force is suppressed so long as the compression amount is within the predetermined range, making it difficult for a large reaction force to occur. As a result, it is possible to avoid damage to the battery due to the reaction force generated by the battery cushioning material. [Industrial Applicability]

[0062] The cushioning material for batteries of the present invention can be used as a cushioning material for batteries such as lithium batteries used in electric vehicles and the like. [Explanation of symbols]

[0063] 10:Connection part 11: Top 13: Bottom 15: Rib 20: Base 20a, 20b: Surface 30: Connector 100, 101, 102, 103, 104, 300: Battery cushioning material 200, 201: Battery 210: Battery cell 230: Restraint part D1, D2: Length of the perpendicular L: Center line O: Center

Claims

1. The device has an upper side portion, a lower side portion, and a plurality of connecting portions connecting the upper side portion and the lower side portion, the connecting portion is made of an elastic material, the connecting portion has one surface at its base portion that is curved and the other surface that is flat, or one surface and the other surface at the base portion that are curved and have different radii of curvature; When an external force of a predetermined magnitude or greater is applied so that the upper edge portion and the lower edge portion approach each other, the connecting portion buckles, thereby suppressing an increase in the reaction force.

2. When one surface of the connecting portion at its base portion is curved and the other surface is flat, the flat surface is located on the outer side, The cushioning material for a battery according to claim 1 , wherein when the curved surfaces have different radii of curvature, the surface located on the outer side has a smaller radius of curvature.

3. The cushioning material for a battery according to claim 1 or 2, wherein the connecting portion is formed by a pair of connecting bodies.

4. 4. The cushioning material for a battery according to claim 1, wherein the connecting portion has a rib attached to the center thereof.

5. A device having an upper edge portion, a lower edge portion, and a plurality of connecting portions connecting the upper edge portion and the lower edge portion, the connecting portion is made of an elastic material, The connecting portion has a rib attached to the center thereof, When an external force of a predetermined magnitude or greater is applied so that the upper edge portion and the lower edge portion approach each other, the connecting portion buckles, thereby suppressing an increase in the reaction force.

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