Battery buffer-material, battery, and method for manufacturing battery buffer-material

Abstract

A battery buffer-material 30 is disposed between adjacent battery cells. The battery buffer-material 30 includes: an elastic member; and a heat-resistant bag 34 which envelops the elastic member and which is configured so that if the elastic member generates a gas which exceeds a prescribed concentration, the gas does not come into contact with a battery cell. The heat-resistant bag 34 is formed by bonding peripheral edges of a sheet to each other.

Description

Battery cushioning material, battery, and method for manufacturing battery cushioning material

[0001] The present disclosure relates to a battery cushioning material, a battery, and a method for manufacturing a battery cushioning material.

[0002] Patent Literature 1 discloses a battery cushioning material that is disposed between adjacent battery cells in a battery having a plurality of battery cells. By disposing the battery cushioning material between the adjacent battery cells, it is possible to absorb volume changes of the battery cells that occur during charging and discharging.

[0003] WO 2023 / 199820

[0004] The present disclosure has been made in light of the above circumstances, and one exemplary purpose of an embodiment thereof is to provide a cushioning material for a battery that is relatively easy to manufacture and has high commercial value.

[0005] In order to solve the above problems, a battery cushioning material according to one aspect of the present disclosure is a battery cushioning material disposed between adjacent battery cells, and includes an elastic member and a heat-resistant bag that encases the elastic member and is configured to prevent the gas, if generated by the elastic member, from coming into contact with the battery cells at a concentration exceeding a predetermined value. The heat-resistant bag is formed by joining the peripheral edges of sheets together.

[0006] Another aspect of the present disclosure includes a plurality of battery cells and the above-described battery cushioning material disposed between adjacent battery cells.

[0007] Another aspect of the present disclosure is a method for manufacturing a cushioning material for a battery. The method is for manufacturing a cushioning material for a battery to be disposed between adjacent battery cells, and includes wrapping an elastic member in a heat-resistant bag. The heat-resistant bag is configured to prevent gas generated by the elastic member from coming into contact with the battery cells at a concentration exceeding a predetermined value. The wrapping in the heat-resistant bag includes joining peripheral edges of sheets stacked to sandwich the elastic member therebetween to form the heat-resistant bag.

[0008] According to the present disclosure, it is possible to provide a cushioning material for a battery with increased commercial value.

[0009] 1 is a diagram showing an example of a battery including a battery cushioning material according to a first embodiment; FIG. 2 is a diagram showing the battery cushioning material according to the first embodiment as viewed in the stacking direction; FIG. 3 is a diagram showing a state of use of the battery cushioning material according to the first embodiment; FIG. 4 is a diagram showing a state of a battery cell and its surroundings when the temperature of the battery cell becomes high; FIG. 5 is a manufacturing process diagram showing an example of a method of manufacturing the battery cushioning material according to the first embodiment; FIG. 6 is a diagram showing the battery cushioning material according to the second embodiment as viewed in the stacking direction; FIG. 7 is a diagram showing a state of use of the battery cushioning material according to the second embodiment; FIG. 8 is a diagram showing the battery cushioning material according to the second modified example as viewed in the stacking direction; FIG. 9 is a diagram explaining an example of a method of manufacturing a heat-resistant bag for a battery cushioning material according to the second modified example; FIG. 10 is a schematic diagram showing a battery according to a third modified example; FIG. 11 is a diagram showing a state of use of the battery cushioning material according to the fourth modified example.

[0010] The present disclosure will be described below based on preferred embodiments with reference to the drawings. The embodiments are illustrative and do not limit the disclosure, and all features and combinations described in the embodiments are not necessarily essential to the disclosure. The same or equivalent components, parts, and processes shown in each drawing will be designated by the same reference numerals, and redundant descriptions will be omitted as appropriate.

[0011] 1 is a diagram showing an example of a battery 1 including a battery cushioning material 30 according to the first embodiment. The battery 1 is, for example, a lithium-ion battery, a nickel-metal hydride battery, or an all-solid-state battery. In this embodiment, the battery 1 includes a restraint device 10, a plurality of battery cells 20, and a plurality of battery cushioning materials 30.

[0012] The restraint device 10 includes a case 11 and a pair of clamping members 12. The case 11 is formed in a tubular shape with both ends open. The case 11 may be formed in a cylindrical shape with a circular cross section, or in a rectangular tubular shape with a polygonal (e.g., rectangular) cross section. The case 11 is made of, for example, metal.

[0013] A stack of multiple battery cells 20 and multiple battery cushioning materials 30 stacked alternately is housed inside the case 11. The stacking direction of the stack (the left-right direction in FIG. 1 ) coincides with the direction parallel to the central axis of the cylindrical case 11 (i.e., the axial direction).

[0014] The pair of clamping members 12 are arranged to close the openings at both ends of the case 11, and are fixed to the case 11 by screws or the like. The pair of clamping members 12 clamp the stack in the stacking direction. The pair of clamping members 12 are made of, for example, metal.

[0015] The battery cell 20 is the smallest structural unit of a battery such as a lithium-ion battery. The battery cell 20 includes an exterior casing 21 and battery elements (not shown) enclosed within the exterior casing 21. The battery elements include, for example, a positive electrode, a negative electrode, a separator, and an electrolyte. The battery cell 20 may be a laminated (pouch) battery cell in which the exterior casing 21 is film-shaped, or may be a rectangular or cylindrical battery cell.

[0016] The battery cushioning material 30 is disposed between adjacent battery cells 20. As shown in the figure, one battery cushioning material 30 may be disposed between adjacent battery cells 20, or multiple stacked battery cushioning materials 30 may be disposed. In either case, by disposing the battery cushioning material 30 between adjacent battery cells 20, the distance between the adjacent battery cells 20 can be ensured.

[0017] By ensuring a distance between adjacent battery cells 20, heat transfer from one battery cell 20 to the adjacent battery cell 20 can be suppressed.

[0018] The thicker the battery cushioning material 30, specifically the thicker the elastic member 32 described below in the stacking direction, the greater the distance between adjacent battery cells 20. In other words, the distance between adjacent battery cells 20 can be adjusted by adjusting the thickness of the elastic member 32 in the stacking direction.

[0019] The battery cushioning material 30 is disposed between the battery cell 20 and the clamping member 12. As shown in the figure, one battery cushioning material 30 may be disposed between the battery cell 20 and the clamping member 12, or multiple stacked battery cushioning materials 30 may be disposed.

[0020] The battery cells 20 expand when charged and contract when discharged. That is, the volume of the battery cells 20 changes with charging and discharging. In contrast, the battery cushioning material 30 is elastically deformable, as will be described in detail later, and absorbs the volume change of the battery cells 20 by utilizing this elasticity. This prevents the battery 1 from being damaged by the volume change of the battery cells 20.

[0021] Fig. 2 is a view of the battery cushioning material 30 viewed in the stacking direction. Fig. 3 is a view showing the battery cushioning material 30 in use. The cross-sectional view of the battery cushioning material 30 in Fig. 3 corresponds to the cross-sectional view taken along line A-A in Fig. 2.

[0022] The battery cushioning material 30 includes an elastic member 32 and a heat-resistant bag 34 .

[0023] The elastic member 32 is formed in a plate shape. The material of the elastic member 32 is not particularly limited as long as it is elastically deformable, that is, can absorb the volume change of the battery cell 20.

[0024] Here, "elastically deformable" means having flexibility that allows deformation and recovery. Specifically, for example, it means having flexibility that allows deformation in response to an external force caused by a volume change of the battery cell 20, and having recovery ability that allows the battery to return to its original shape when the external force is removed after deformation due to the external force. Note that the original shape here is not limited to a shape that is completely the same as before deformation due to the external force, but also includes a shape that is approximately the same as before deformation due to the external force.

[0025] For example, the material of the elastic member 32 may be rubber, a resin-based elastomer, fibers such as nonwoven fabric, inorganic particles, inorganic fibers, or a heat insulating material containing an organic binder or the like.

[0026] The elastic member 32 may be a porous body. Specifically, the elastic member 32 may be, for example, a foam body. Furthermore, the elastic member 32 may be, for example, a porous body having a honeycomb structure. When the elastic member 32 is a porous body, it is easy to exhibit elasticity, and a sudden increase in pressure can be suppressed. Furthermore, since the elastic member 32 contains a large amount of air, heat transfer from one battery cell 20 to another battery cell 20 via the elastic member 32 can be suppressed.

[0027] The elastic member 32 preferably has a high compressibility. In this case, the increase in the reaction force is small even if the amount of compression of the elastic member 32 increases. If the elastic member 32 is a foam, the foaming rate may be determined based on the desired compressibility.

[0028] The heat-resistant bag 34 encases the entire elastic member 32. The heat-resistant bag 34 is airtight and seals the entire elastic member 32. As a result, even if the elastic member 32 undergoes a decomposition reaction (for example, thermal decomposition) and generates gas, the gas is trapped in the heat-resistant bag 34 and does not leak out of the heat-resistant bag 34.

[0029] The heat-resistant bag 34 is configured to be deformable in response to the deformation of the elastic member 32 when the elastic member 32 deforms. Therefore, the heat-resistant bag 34 is configured to at least allow the deformation of the elastic member 32. The heat-resistant bag 34 is preferably configured not to hinder the deformation of the elastic member 32. In other words, the heat-resistant bag 34 is preferably configured to have the same or lower rigidity as the elastic member 32, i.e., to have rigidity equal to or less than that of the elastic member 32. To achieve this, the heat-resistant bag 34 may be formed to be thinner than at least the elastic member 32.

[0030] The heat-resistant bag 34 may have a bulge. That is, the volume of the heat-resistant bag 34 when fully inflated with gas may be larger than the volume of the elastic member 32. In this case, the thickness of the battery cushioning material 30 in the stacking direction when the heat-resistant bag 34 is fully inflated is greater than the original thickness of the battery cushioning material 30, i.e., the thickness of the battery cushioning material 30 before the elastic member 32 generates gas and the heat-resistant bag 34 inflates. Therefore, when the heat-resistant bag 34 is fully inflated, the distance between the two battery cells 20 sandwiching the battery cushioning material 30 is longer than the original distance, i.e., the distance before the elastic member 32 generates gas and the heat-resistant bag 34 inflates. This further suppresses heat transfer between the two battery cells 20 sandwiching the battery cushioning material 30.

[0031] The heat-resistant bag 34 may have higher thermal insulation properties than the elastic member 32. In this case, compared to when the battery cushioning material 30 does not include the heat-resistant bag 34, heat is less likely to be transmitted to the elastic member 32, and therefore the elastic member 32 is less likely to reach a high temperature, and therefore the elastic member 32 is less likely to undergo a decomposition reaction, i.e., to generate gas.

[0032] The heat-resistant bag 34 may have the same or lower thermal insulation properties as the elastic member 32. In this case, because heat is easily transferred to the elastic member 32, the elastic member 32 is likely to reach a high temperature, and therefore the elastic member 32 is likely to undergo a decomposition reaction, i.e., to generate gas, and the heat-resistant bag 34 becomes swollen with the generated gas, making it possible to ensure a distance between adjacent battery cells 20, as will be described in detail later.

[0033] The heat-resistant bag 34 has a heat-resistant temperature that is higher than the lowest temperature at which the elastic member 32 undergoes a decomposition reaction (thermal decomposition) and generates gas. The heat-resistant temperature here may be a temperature at which the heat-resistant bag 34 can maintain its shape. In this case, even if the elastic member 32 undergoes a decomposition reaction and generates gas, the heat-resistant bag 34 can maintain its shape as long as the heat-resistant temperature is below the heat-resistant temperature, and the gas is therefore sealed in the heat-resistant bag 34.

[0034] The above is the basic configuration of the battery cushioning material 30. Next, the effects thereof will be described.

[0035] Fig. 4 is a diagram showing the state of a certain battery cell 20_i and its surroundings when the temperature of the battery cell 20_i becomes high in the battery 1. In Fig. 4, heat from the battery cell 20_i is transferred to the elastic members 32_i and 32_i+1 of the battery cushioning materials 30_i and 30_i+1 adjacent to the battery cell 20_i, causing a decomposition reaction in the elastic members 32_i and 32_i+1, and generating gas from the elastic members 32_i and 32_i+1.

[0036] Even if gas is generated from the elastic members 32_i and 32_i+1, the elastic members 32_i and 32_i+1 are sealed by the heat-resistant bags 34_i and 34_i+1, so the gas is confined in the heat-resistant bags 34_i and 34_i+1 and does not leak out of the heat-resistant bags 34_i and 34_i+1. Therefore, the gas cannot come into contact with the battery cell 20_i. In other words, although it is undesirable for the gas generated from the elastic members 32_i and 32_i+1 to come into contact with the battery cell 20_i, the gas is managed by the heat-resistant bags 34_i and 34_i+1 to prevent it from coming into contact with the battery cell 20_i.

[0037] Furthermore, if the elastic members 32_i, 32_i+1 are heated to the point where a decomposition reaction occurs, they may lose their function as elastic members and remain compressed, never recovering. In response to this, because gas does not leak out of the heat-resistant bags 34_i, 34_i+1, the internal pressure of the heat-resistant bags 34_i, 34_i+1 increases, causing the heat-resistant bags 34_i, 34_i+1 to become swollen with gas. This ensures a sufficient distance between the battery cell 20_i and the adjacent battery cells 20_i-1, 20_i+1, even when the battery cell 20_i reaches a high temperature, thereby suppressing heat transfer from the battery cell 20_i to the battery cells 20_i-1, 20_i+1. If the heat-resistant bags 34_i, 34_i+1 have a bulge allowance, the heat-resistant bags 34_i, 34_i+1 will bulge to their full capacity, causing the battery cushioning materials 30_i, 30_i+1 to become larger than before, i.e., thicker in the stacking direction than before, and the distance between the battery cell 20_i and the battery cells 20_i-1, 20_i+1 will also become longer than before.

[0038] By adjusting the amount of elastic member 32, the amount of gas generated when the elastic member 32 undergoes a decomposition reaction, and therefore the internal pressure of the heat-resistant bag 34, can be adjusted.

[0039] These are the effects of the basic configuration of the battery cushioning material 30. Next, the heat-resistant bag 34 will be described in detail with reference to FIGS.

[0040] The heat-resistant bag 34 is formed from two sheets 131 and 132. The two sheets 131 and 132 are typically made of a metal that can withstand a high heat temperature. For example, the two sheets 131 and 132 may be made of aluminum, copper, stainless steel, or tungsten. The metal used for the two sheets 131 and 132 may be determined depending on the heat-resistant temperature required for the heat-resistant bag 34. Note that the two sheets 131 and 132 are not limited to being made of metal as long as they meet the required heat-resistant temperature.

[0041] The heat-resistant bag 34 is formed by stacking the first sheet 131 and the second sheet 132 so as to sandwich the elastic member 32 therebetween, and joining the peripheral edge 131 a of the first sheet 131 and the peripheral edge 132 a of the second sheet 132. In this case, it is relatively easy to fit the elastic member 32 into the heat-resistant bag 34, and therefore the battery cushioning material 30 can be easily manufactured.

[0042] The peripheral portions 131 a and 132 a are portions that form the peripheral portion 34 a of the heat-resistant bag 34 .

[0043] The peripheral edges 131 a, 132 a may be considered to be portions located outside the elastic member 32 when the battery cushioning material 30 is viewed in the stacking direction. The peripheral edge 34 a of the heat-resistant bag 34 is a portion located outside the elastic member 32 when the battery cushioning material 30 is viewed in the stacking direction.

[0044] The peripheral edge 34a of the heat-resistant bag 34 may be considered to be a portion having a folding structure (described later). In this example, the peripheral edge 34a of the heat-resistant bag 34 has a rectangular frame shape when viewed in the stacking direction of the battery cushioning material 30. In Figure 2(a) , the peripheral edge 34a is indicated by hatching.

[0045] In this embodiment, the joining method is welding or welding. Therefore, the peripheral edge 34a of the heat-resistant bag 34 has a joint (joint line) 34b, which is a portion joined by welding or welding. In FIG. 2(a), the joint 34b is indicated by a dashed line. In this embodiment, the joint 34b has a continuous ring shape when the battery cushioning material 30 is viewed in the stacking direction. In this embodiment, the peripheral edge 34a of the heat-resistant bag 34 has a single ring-shaped joint 34b, but may have two or more ring-shaped joints 34b.

[0046] The welding is not particularly limited, but may be, for example, laser welding or electron beam welding. The welding is not particularly limited, but may be, for example, laser welding, heat welding or ultrasonic welding.

[0047] Here, it is natural to use adhesive to join the two sheets 131, 132 because it is inexpensive and easy. However, the battery cells 20 may reach high temperatures, and the heat-resistant bag 34 may be exposed to high temperatures. If adhesive is used to join the two sheets 131, 132, the adhesive may be exposed to high temperatures and lose its adhesive strength, causing the two sheets 131, 132 to at least partially separate, and the heat-resistant bag 34 to at least partially open. In this case, if the elastic member 32 generates gas, the gas will leak from the heat-resistant bag 34.

[0048] In contrast, in this embodiment, the peripheral edges 131a, 132a of the two sheets 131, 132 are joined by welding or fusion, so there is no problem of the joint coming loose due to high temperatures.

[0049] In the illustrated example, the thickness of the peripheral portion 34a of the heat-resistant bag 34 is thicker than the combined thickness of the non-peripheral portion 131b of the first sheet 131 and the non-peripheral portion 132b of the second sheet 132, i.e., thicker than the combined thickness of the non-peripheral portion 131b of the first sheet 131 and the non-peripheral portion 132b of the second sheet 132; in other words, it is relatively thick. The non-peripheral portion 131b of the first sheet 131 is the portion inside the peripheral portion 131a and surrounded by the peripheral portion 131a. The non-peripheral portion 132b of the second sheet 132 is the portion inside the peripheral portion 132a and surrounded by the peripheral portion 132a.

[0050] Here, when welding the peripheral portion 34a of the heat-resistant bag 34 by laser welding, if the output of the laser beam is too high, burn-through occurs, and if the output of the laser beam is too low, melting at the joining interface becomes insufficient. In other words, if the output of the laser beam is not within the allowable range, poor joining occurs. Generally, the output of the laser beam is not constant but fluctuates, so if the allowable range is narrow, the output of the laser beam will not fall within the allowable range, resulting in poor joining. This allowable range is narrower the thinner the peripheral portion 34a, and wider the thicker the peripheral portion 34a. Therefore, if the peripheral portion 34a of the heat-resistant bag 34 is relatively thick, the output of the laser beam is more likely to fall within the allowable range, and poor joining is less likely to occur. The same can be said for other welding and deposition methods.

[0051] Furthermore, when the peripheral edge 34a of the heat-resistant bag 34 is relatively thick, the peripheral edge 34a has higher rigidity than when it is thin, and is therefore less likely to deform. Therefore, even if there is a poorly joined portion at the joint 34b of the peripheral edge 34a, the gap at the poorly joined portion is less likely to widen, and even if the elastic member 32 generates gas, the gas is less likely to leak out of the heat-resistant bag 34 from the poorly joined portion.

[0052] To achieve a relatively thick peripheral portion 34a, the peripheral portion 34a of the heat-resistant bag 34 may have a folded structure. "The peripheral portion 34a of the heat-resistant bag 34 has a folded structure" means that at least one of the peripheral portion 131a of the first sheet 131 and the peripheral portion 132a of the second sheet 132 that constitute the peripheral portion 34a of the heat-resistant bag 34 is folded.

[0053] The peripheral edge 131a of the first sheet 131 and the peripheral edge 132a of the second sheet 132 may be folded together, i.e., integrally. This allows the path R (shown by the thick solid line in FIG. 3 ) from the peripheral edge 34a to the outside of the heat-resistant bag 34 to be complex, even if the elastic member 32 generates gas, making it difficult for the gas to leak outside the heat-resistant bag 34. When the peripheral edges 131a and 132a are folded together, they may be folded once or twice or more (i.e., multiple times). The more times the sheet is folded, the more complex the path R becomes, increasing the flow resistance and making it difficult for gas to leak. When the sheet is folded twice or more, the folding method may be zigzag or spiral.

[0054] As a modified example, when the peripheral portions 131 a, 132 a of the two sheets 131, 132 are folded together, the sheets may be folded so that the edges 131 c, 132 c of the peripheral portions 131 a, 132 a of the two sheets 131, 132 are not exposed. For example, this can be achieved by folding the peripheral portions 131 a, 132 a together in a roll, in other words, by folding them together in the same direction two or more times (by repeating valley folds). In this case, even if there is a poor joint at the joint 34 b of the peripheral portion 34 a, the outlet of the gas path R is located on the inside, making it less likely for gas to leak.

[0055] Alternatively, to achieve a relatively thick peripheral portion 34a, the peripheral portions 131a, 132a of the sheets 131, 132 may be thicker than the non-peripheral portions 131b, 132b. If thick sheets 131, 132 are used overall to achieve a relatively thick peripheral portion 34a, that is, if thick sheets are used not only for the peripheral portions 131a, 132a but also for the non-peripheral portions 131b, 132b, the thickness may exceed the allowable thickness for the battery cushioning material 30, or it may be necessary to thin the thickness of the elastic member 32 so as not to exceed the allowable thickness for the battery cushioning material 30. In contrast, if sheets 131, 132 with thick peripheral portions 131a, 132a only are used, such a problem does not arise.

[0056] This concludes the detailed description of the heat-resistant bag 34. Next, a method for manufacturing the battery cushioning material 30 will be described.

[0057] 5 is a manufacturing process diagram showing an example of a manufacturing method for battery cushioning material 30. This manufacturing method includes a preparation step S10 of preparing elastic member 32 and two sheets 131, 132, a wrapping step S12 of wrapping elastic member 32 in heat-resistant bag 34, and an inspection step S14 of inspecting the appearance of battery cushioning material 30.

[0058] The wrapping step S12 includes a heat-resistant bag forming step S16. In the heat-resistant bag forming step S16, two sheets 131, 132 are stacked together to sandwich the elastic member 32, and then, for example, the peripheral edges 131 a, 132 a of the two sheets 131, 132 are folded together and the peripheral edges 131 a, 132 a of the two sheets 131, 132 are joined by welding or fusion bonding to form the heat-resistant bag 34 and wrap the elastic member 32. This completes the battery cushioning material 30.

[0059] As described above, according to this embodiment, the elastic member 32 is sealed by the heat-resistant bag 34. Therefore, even if gas is generated from the elastic member 32, the gas is trapped in the heat-resistant bag 34 and does not leak out of the heat-resistant bag 34. Therefore, the gas cannot come into contact with the battery cells 20. Furthermore, the heat-resistant bag 34 is formed by stacking two sheets 131, 132 so as to sandwich the elastic member 32 therebetween and joining their peripheral edges 131a, 132a. In this case, it is relatively easy to fit the elastic member 32 into the heat-resistant bag 34, and therefore the battery cushioning material 30 can be easily manufactured. In other words, according to this embodiment, it is possible to provide a battery cushioning material 30 that is relatively easy to manufacture and has high commercial value.

[0060] Furthermore, according to this embodiment, the peripheral portions 131a, 132a of the two sheets 131, 132 are joined by welding or fusion, so there is no problem of the joint coming loose due to high temperatures, as occurs when the sheets are joined by adhesive.

[0061] Second Embodiment Fig. 6 is a view of a battery cushioning material 30 according to a second embodiment, viewed in the stacking direction. Fig. 7 is a view showing the battery cushioning material 30 in use. The cross-sectional view of the battery cushioning material 30 in Fig. 7 corresponds to the cross-sectional view taken along line B-B in Fig. 6.

[0062] The second embodiment differs from the first embodiment in that the heat-resistant bag 34 is formed from two sheets 131, 132 by crimping and joining the peripheral edges of the two sheets 131, 132. The following description of the second embodiment will focus on the differences from the first embodiment, and will omit a description of the commonalities as appropriate.

[0063] The heat-resistant bag 34 is formed by two sheets 131 and 132. The two sheets 131 and 132 are typically made of a metal that can withstand a high heat temperature, but are not limited to metal as long as the required heat-resistant temperature is met. Specifically, the heat-resistant bag 34 is formed by stacking the first sheet 131 and the second sheet 132 so as to sandwich the elastic member 32 therebetween, and joining the peripheral edge 131 a of the first sheet 131 and the peripheral edge 132 a of the second sheet 132.

[0064] In this embodiment, the joining method is crimping. In this example, the peripheral edge 131 a of the first sheet 131 and the peripheral edge 132 a of the second sheet 132 are crimped and joined together using a crimping member 50. The material of the crimping member 50 is not particularly limited. For example, the crimping member 50 may be formed from a metal such as brass, copper, or stainless steel. In this example, the crimping member 50 is plate-shaped, and the crimping member 50 is folded in two to sandwich the peripheral edge 131 a of the first sheet 131 and the peripheral edge 132 a of the second sheet 132, thereby crimping the peripheral edge 131 a of the first sheet 131 and the peripheral edge 132 a of the second sheet 132.

[0065] In this embodiment, the peripheral edges 131a and 132a of the two sheets 131 and 132 are joined by caulking, so that, as in the first embodiment, there is no problem of the joint coming loose due to high temperatures.

[0066] The number and size of the crimping members 50 are not particularly limited and may be determined based on experiments, etc. Note that the shorter the interval between adjacent crimping members 50, the less likely gas will leak when gas is generated by the elastic member 32.

[0067] In the illustrated example, the thickness of the peripheral portion 34a of the heat-resistant bag 34 is thicker than the combined thickness of the non-peripheral portion 131b of the first sheet 131 and the non-peripheral portion 132b of the second sheet 132, as in the first embodiment. That is, it is thicker than the combined thickness of the non-peripheral portion 131b of the first sheet 131 and the non-peripheral portion 132b of the second sheet 132. In other words, it is relatively thick. As in the first embodiment, this may be achieved by the peripheral portion 34a of the heat-resistant bag 34 having a folded structure, or by the peripheral portions 131a, 132a of the sheets 131, 132 being thicker than the non-peripheral portions 131b, 132b. The effect obtained by the relatively thick peripheral portion 34a of the heat-resistant bag 34 is the same as in the first embodiment.

[0068] The manufacturing method of the battery cushioning material 30 can be achieved by replacing the welding or fusion bonding in the heat-resistant bag forming step S16 in FIG. 5 with crimping bonding.

[0069] According to this embodiment, it is possible to achieve the same effects as those of the first embodiment.

[0070] The present disclosure has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and processing steps, and that such modifications are also within the scope of the present disclosure. Such modifications will be described below.

[0071] (First Modification) Folding the peripheral edge 131 a of the first sheet 131 and the peripheral edge 132 a of the second sheet 132 together can also be considered as a crimping joint. Therefore, unlike the second embodiment described above, the battery cushioning material 30 does not include the crimping material 50, and the peripheral edge 131 a of the first sheet 131 and the peripheral edge 132 a of the second sheet 132 may simply be folded together. This modification can achieve the same effects as the second embodiment.

[0072] (Second Modification) Unlike the above-described embodiment, the heat-resistant bag 34 may have an outlet for discharging gas. The following description will focus on the differences from the first embodiment, and will omit a description of the commonalities as appropriate.

[0073] Although the following description will be given taking as an example a case where the joining method is welding or fusion bonding, as in the first embodiment, the technical concept of this modification can also be applied to a case where the joining method is caulking joining, as in the second embodiment. The same applies to the third and fourth modifications described below.

[0074] Fig. 8 is a view of the battery cushioning material 130 according to the second modified example, viewed in the stacking direction. Fig. 9 is a view showing the battery cushioning material 130 in use. The cross-sectional view of the battery cushioning material 130 in Fig. 9 corresponds to the cross-sectional view taken along line CC in Fig. 8.

[0075] The battery cushioning material 130 is configured in the same manner as the battery cushioning material 30 according to the first embodiment, except that the heat-resistant bag 34 has an outlet 34c.

[0076] The heat-resistant bag 34 has an outlet 34c for discharging gas, and seals the entire elastic member 32 so that gas is not discharged from any other outlet than the outlet 34c. The number of outlets 34c is not important. There may be one outlet 34c as shown in the figure, or two or more outlets (i.e., multiple outlets).

[0077] The heat-resistant bag 34 includes a heat-resistant bag main body 134 that seals the entire elastic member 32, and a duct 136 that connects the inside and outside of the heat-resistant bag main body 134. The description of the heat-resistant bag in the first embodiment applies to the heat-resistant bag main body 134 unless inconsistencies arise. That is, the heat-resistant bag main body 134 is formed by overlapping a first sheet 131 and a second sheet 132 so as to sandwich the elastic member 32 therebetween, and joining a peripheral edge 131 a of the first sheet 131 to a peripheral edge 132 a of the second sheet 132. The peripheral edge 34 a of the heat-resistant bag 34 can also be considered as the peripheral edge of the heat-resistant bag main body 134.

[0078] The outlet of the duct 136 constitutes the exhaust port 34c. The duct 136 communicates between the inside of the heat-resistant bag 34 and the outside of the battery 1. More specifically, one end 136a of the duct 136 is connected to the heat-resistant bag 34. The other end 136b of the duct 136, i.e., the exhaust port 34c serving as the outlet, is located outside the battery 1. That is, the heat-resistant bag 34 has the exhaust port 34c in a position where gas discharged from the exhaust port 34c does not come into contact with the battery cells 20. As a result, when a decomposition reaction occurs in the elastic member 32 and gas is generated, the gas does not leak into the inside of the case 11, i.e., does not come into contact with the battery cells 20, but is released to the outside of the battery 1 through the duct 136.

[0079] The material of the duct 136 is not particularly limited, but preferably, like the heat-resistant bag body 134, it has a heat-resistant temperature higher than the lower limit temperature at which the elastic member 32 undergoes a decomposition reaction and generates gas.

[0080] The duct 136 may be formed separately from the heat-resistant bag body 134 and then joined to the heat-resistant bag body 134 .

[0081] The duct 136 may be formed from the same material as the heat-resistant bag body 134. In this case, the duct 136 may be formed integrally with the heat-resistant bag body 134.

[0082] 10 is a diagram illustrating an example of a manufacturing method for the heat-resistant bag 34 when the heat-resistant bag main body 134 and the duct 136 are integrally formed. Each of the sheets 131 and 132 has a first portion 144 that constitutes the heat-resistant bag main body 134 and a second portion 146 that protrudes from the first portion 144 and constitutes the duct 136. The first portion 144 is rectangular in shape, although not limited thereto, in the illustrated example. The second portion 146 is elongated in shape, although not limited thereto, in the illustrated example. The heat-resistant bag 34, i.e., the heat-resistant bag main body 134 and the duct 136, are formed by joining the peripheries of the two sheets 131 and 132, excluding the tip portion 146a of the second portion 146.

[0083] In this case, there is no seam between the heat-resistant bag body 134 and the duct 136, so gas does not leak between the heat-resistant bag body 134 and the duct 136. Furthermore, because the heat-resistant bag body 134 and the duct 136 can be formed at one time, labor costs are lower and tact time can be shortened compared to when they are formed separately and then joined together.

[0084] The peripheral portion 34a of the heat-resistant bag 34 may be relatively thick, and may have, for example, a folded structure to achieve this. The peripheral portion of the duct 136 may also be relatively thick, and may have, for example, a folded structure to achieve this.

[0085] 8 and 9. As in the first embodiment, the elastic member 32 may be made of any material as long as it is elastically deformable, that is, as long as it can absorb the volumetric changes of the battery cells 20, but if the elastic member 32 is porous, gas will easily flow through the heat-resistant bag 34, and therefore the gas will be easily discharged.

[0086] Next, the effects of this modification will be described. According to this modification, even if a certain battery cell 20 becomes hot and the battery cushioning material 130 adjacent to that battery cell 20 is heated, causing gas to be generated from the elastic member 32, the gas is not discharged from anywhere other than the exhaust port 34c. In other words, the gas is released directly to the outside of the battery 1 and does not leak into the inside of the case 11. Therefore, the gas cannot come into contact with the battery cell 20. In other words, the gas generated from the elastic member 32 is managed by the heat-resistant bag 34 so as not to come into contact with the battery cell 20.

[0087] Furthermore, according to this embodiment, the gas is released to the outside of the battery 1 through the duct 136, which prevents an excessive increase in the internal pressure of the heat-resistant bag 34. This reduces the risk of damage to the heat-resistant bag 34. Alternatively, the sheets 131, 132 of the heat-resistant bag 34 do not need to be joined with such high strength.

[0088] (Third Variant) In the second variant described above, the duct 136 connects the inside of the heat-resistant bag 34 with the outside of the battery 1, and the gas generated by the elastic member 102 is released to the outside of the battery 1. However, this is not limited to this, and the duct 136 may release the gas generated by the elastic member 102 into the inside of the battery 1 as long as high-concentration gas does not come into contact with the battery cell 20.

[0089] 11 is a schematic diagram showing a battery 1 according to a third modified example. The following description will focus on the differences from the second modified example, and a description of the commonalities will be omitted as appropriate.

[0090] In this modification, the battery 1 includes a plurality of battery cells 20 , a plurality of battery cushioning materials 130 , and a cooler 40 for cooling the plurality of battery cells 20 .

[0091] The cooler 40 cools the battery cells 20 by discharging relatively high-temperature air from inside the battery 1 and drawing in relatively low-temperature air from outside the battery 1. The cooler 40 may include a cooling unit that cools the air drawn in from outside the battery 1. In either case, by providing the battery 1 with the cooler 40, an air flow is generated inside the battery 1, and the air inside the battery 1 is constantly replaced with air outside the battery 1.

[0092] In this modified example, the other end 136b of the duct 136, i.e., the outlet 34c which is the outlet, is located inside the battery 1. Therefore, when the elastic member 102 generates gas, the gas is released into the inside of the battery 1. In this case, the outlet 34c is provided at a position where the gas discharged from the outlet 34c does not come into contact with the battery cells 20, or at a position where the concentration of the gas discharged from the outlet 34c falls below a predetermined concentration before it comes into contact with the battery cells 20. This prevents the gas from coming into contact with the battery cells 20, or only low-concentration gas comes into contact with the battery cells 20.

[0093] For example, as shown in the figure, the exhaust port 34c is located closer to the cooler 40 than to the battery cell 20. Specifically, the exhaust port 34c is located where a distance L1 between the exhaust port 34c and the cooler 40 and a distance L2 between the exhaust port 34c and the battery cell 20 closest thereto satisfy distance L1 < distance L2. In this case, the gas generated by the elastic member 32 is released to a position relatively far from the battery cell 20 but relatively close to the cooler 40, and is then exhausted to the outside of the battery 1.

[0094] Further, for example, the exhaust port 34c may be connected in communication with the cooler 40. In this case, the gas is released from the exhaust port 34c into the inside of the cooler 40, and then exhausted to the outside of the battery 1 from there.

[0095] Further, for example, the exhaust port 34c may be located at a position that protrudes beyond the battery cells 20 in a direction perpendicular to the stacking direction (the up-down direction or depth direction in FIG. 11 ). In other words, as shown in FIG. 8 , the exhaust port 34c may be located at the periphery of the heat-resistant bag 34 when the battery cushioning material is viewed in the stacking direction. In this case, because there is an air flow due to the cooler 40 at the exhaust port 34c, the gas is immediately diluted by the air and is exhausted to the outside of the battery 1 together with the air.

[0096] According to these modified examples, the heat-resistant bag 34 is used to prevent gas from coming into contact with the battery cells 20 or to ensure that only low concentrations of gas come into contact with the battery cells 20 .

[0097] (Fourth Modification) Unlike the above-described third modification, the heat-resistant bag 34 does not need to include the duct 136 .

[0098] Fig. 12 is a diagram showing a state in which the battery cushioning material 130 according to the fourth modified example is used. Fig. 12 corresponds to Fig. 9. Below, differences from the third modified example will be mainly described, and descriptions of commonalities will be omitted as appropriate.

[0099] In this modified example, the heat-resistant bag 34 includes only the heat-resistant bag main body 134. In other words, the heat-resistant bag 34 does not include a duct. The exhaust port 34c is provided in the heat-resistant bag main body 134. In this case, the exhaust port 134c is provided at a position where the concentration of the gas exhausted from the exhaust port 34c falls below a predetermined concentration before it comes into contact with the battery cells 20. This ensures that only low-concentration gas comes into contact with the battery cells 20.

[0100] For example, the exhaust port 34c may be located at the peripheral edge 34a of the heat-resistant bag 34. In this case, because there is an air flow through the exhaust port 34c due to the cooler 40, the gas is immediately diluted by the air and is exhausted together with the air to the outside of the battery 1. The number of exhaust ports 34c is not particularly limited and may be one or two or more (i.e., multiple). For example, multiple exhaust ports 34c may be provided along the peripheral edge 34a of the heat-resistant bag 34.

[0101] According to this modification, the heat-resistant bag 34 manages so that only low-concentration gas comes into contact with the battery cell 20 .

[0102] (Fifth Modification) In the above-described embodiment and modifications, the heat-resistant bag 34 is formed from two sheets 131, 132. However, the heat-resistant bag 34 may be formed from a single sheet. In this case, the heat-resistant bag 34 may be formed by folding a single sheet in half to sandwich the elastic member 32 and joining the peripheral edge, specifically the peripheral edge other than the fold. In other words, the first sheet 131 and the second sheet 132 may be a single folded sheet that is connected to each other. In this case, the first sheet 131 is the sheet portion on one side of the fold, and the second sheet 132 is the sheet portion on the other side of the fold.

[0103] Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. A new embodiment resulting from the combination has the combined effects of the combined embodiments and modifications.

[0104] The above-described embodiment and modifications can be generalized to obtain the following aspects.

[0105] [Aspect 1] A cushioning material for a battery that is placed between adjacent battery cells, comprising: an elastic member; and a heat-resistant bag that encases the elastic member and is configured to prevent gas that exceeds a predetermined concentration from coming into contact with the battery cell if the elastic member generates gas, wherein the heat-resistant bag is formed by joining the peripheral edges of a sheet together.

[0106] [Aspect 2] The heat-resistant bag includes a first sheet and a second sheet that constitutes the heat-resistant bag together with the first sheet, and the peripheral portion of the heat-resistant bag has a joint where the peripheral portion of the first sheet and the peripheral portion of the second sheet are joined by welding or fusion. This is the battery cushioning material described in Aspect 1.

[0107] [Aspect 3] The heat-resistant bag includes a first sheet and a second sheet that constitutes the heat-resistant bag together with the first sheet, and the peripheral edge of the first sheet and the peripheral edge of the second sheet are crimped and joined together. This is the battery cushioning material described in Aspect 1.

[0108] [Aspect 4] The battery cushioning material according to Aspect 3, wherein the crimping joint is achieved by crimping the peripheral edge of the first sheet and the peripheral edge of the second sheet with a crimping material.

[0109] [Aspect 5] The battery cushioning material according to Aspect 4, wherein the crimping material sandwiches the peripheral edge of the first sheet and the peripheral edge of the second sheet.

[0110] [Aspect 6] The battery cushioning material according to any one of Aspects 2 to 5, wherein the thickness of the peripheral portion of the heat-resistant bag is greater than the combined thickness of the non-peripheral portion of the first sheet and the non-peripheral portion of the second sheet.

[0111] [Aspect 7] The battery cushioning material according to any one of Aspects 2 to 6, wherein the peripheral edge of the heat-resistant bag has a folded structure in which at least one of the peripheral edge of the first sheet and the peripheral edge of the second sheet is folded.

[0112] [Aspect 8] The battery cushioning material according to any one of Aspects 2 to 7, wherein the peripheral edge of the heat-resistant bag has a folded structure in which the peripheral edge of the first sheet and the peripheral edge of the second sheet are folded together.

[0113] [Aspect 9] The battery cushioning material according to any one of Aspects 2 to 8, wherein the peripheral edge of the heat-resistant bag has a folded structure in which the edges of the first sheet and the second sheet are not exposed.

[0114] [Aspect 10] The battery cushioning material according to Aspect 3, wherein the crimping joint is achieved by folding the peripheral edge of the first sheet and the peripheral edge of the second sheet together.

[0115] [Aspect 11] A battery comprising a plurality of battery cells and the battery cushioning material according to any one of Aspects 1 to 10 disposed between adjacent battery cells.

[0116] [Aspect 12] A method for manufacturing a cushioning material for a battery to be placed between adjacent battery cells, the method comprising: wrapping an elastic member in a heat-resistant bag; the heat-resistant bag being configured to prevent gas generated by the elastic member from coming into contact with the battery cell if the gas exceeds a predetermined concentration; and wrapping the elastic member in the heat-resistant bag includes joining the peripheral edges of sheets stacked so as to sandwich the elastic member therebetween to form the heat-resistant bag.

[0117] [Aspect 13] The method for manufacturing a battery cushioning material according to Aspect 12, wherein forming the heat-resistant bag includes welding or fusing together peripheral edges of a first sheet and a second sheet that are stacked so as to sandwich the elastic member therebetween to form the heat-resistant bag.

[0118] [Aspect 14] The method for manufacturing a battery cushioning material according to Aspect 12, wherein forming the heat-resistant bag includes forming the heat-resistant bag by crimping a peripheral edge portion of a first sheet and a peripheral edge portion of a second sheet that are stacked so as to sandwich the elastic member.

[0119] The present disclosure relates to a battery cushioning material, a battery, and a method for manufacturing a battery cushioning material.

[0120] 30, 130 Battery cushioning material, 32 Elastic member, 34 Heat-resistant bag, 34a Peripheral edge portion, 34b Joint portion, 50 Caulking material, 131 First sheet, 131a Peripheral edge portion, 131b Non-peripheral edge portion, 132 Second sheet, 132a Peripheral edge portion, 132b Non-peripheral edge portion.

Claims

1. A cushioning material for batteries that is placed between adjacent battery cells, comprising: an elastic member; and a heat-resistant bag that encases the elastic member and is configured to prevent gas that exceeds a predetermined concentration from coming into contact with the battery cells if the elastic member generates gas, wherein the heat-resistant bag is formed by joining the peripheral edges of a sheet together.

2. The battery cushioning material described in claim 1, wherein the heat-resistant bag includes a first sheet and a second sheet that constitutes the heat-resistant bag together with the first sheet, and the peripheral edge of the heat-resistant bag has a joint where the peripheral edge of the first sheet and the peripheral edge of the second sheet are joined by welding or fusion.

3. The battery cushioning material described in claim 1, wherein the heat-resistant bag includes a first sheet and a second sheet that constitutes the heat-resistant bag together with the first sheet, and the peripheral edge of the first sheet and the peripheral edge of the second sheet are crimped and joined.

4. The battery cushioning material according to claim 3, wherein the crimping joint is achieved by crimping the peripheral edge of the first sheet and the peripheral edge of the second sheet with a crimping material.

5. The battery cushioning material according to claim 4, wherein the crimping material sandwiches the peripheral edge of the first sheet and the peripheral edge of the second sheet.

6. A cushioning material for a battery as described in any one of claims 2 to 5, wherein the thickness of the peripheral portion of the heat-resistant bag is thicker than the combined thickness of the non-peripheral portion of the first sheet and the non-peripheral portion of the second sheet.

7. A cushioning material for a battery as described in any one of claims 2 to 5, wherein the peripheral edge of the heat-resistant bag has a folded structure in which at least one of the peripheral edge of the first sheet and the peripheral edge of the second sheet is folded.

8. A cushioning material for a battery as described in any one of claims 2 to 5, wherein the peripheral edge of the heat-resistant bag has a folded structure in which the peripheral edge of the first sheet and the peripheral edge of the second sheet are folded together.

9. A cushioning material for a battery as described in any one of claims 2 to 5, wherein the peripheral edge of the heat-resistant bag has a folded structure in which the edges of the first sheet and the second sheet are not exposed.

10. The battery cushioning material according to claim 3, wherein the crimping joint is achieved by folding the peripheral edge of the first sheet and the peripheral edge of the second sheet together.

11. A battery comprising: a plurality of battery cells; and the battery cushioning material according to any one of claims 1 to 5, disposed between adjacent battery cells.

12. A method for manufacturing a cushioning material for a battery to be placed between adjacent battery cells, the method comprising wrapping an elastic member in a heat-resistant bag, the heat-resistant bag being configured so that if the elastic member generates gas, the gas will not come into contact with the battery cell if the gas exceeds a predetermined concentration, and the wrapping in the heat-resistant bag includes forming the heat-resistant bag by joining the peripheral edges of sheets that are stacked so as to sandwich the elastic member.

13. A method for manufacturing a cushioning material for a battery as described in claim 12, wherein forming the heat-resistant bag includes forming the heat-resistant bag by welding or fusing together the peripheral edges of a first sheet and a second sheet that are stacked so as to sandwich the elastic member.

14. A method for manufacturing a cushioning material for a battery as described in claim 12, wherein forming the heat-resistant bag includes forming the heat-resistant bag by crimping the peripheral edges of a first sheet and a second sheet that are stacked so as to sandwich the elastic member.

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